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WirelessHD

2011-01-03T06:37:00.000-08:00

WirelessHD is supposed to be the first and only wireless digital interface to combine uncompressed HD video content, hi-definition surround audio, intelligent format recognition and control data. For consumers, elimination of cables for audio and video dramatically simplifies home theater system installation and eliminates the traditional need to locate source devices in the proximity of the display. The technology will support the legacy systems by means of specialized adapter solutions, that will be capable of supporting the new formats. This is the first global standard for 60 GHz applications based on the IEEE 802.15.3c specification. It enables high performance, interoperable, multi-gigabit speed wireless communications among consumer electronics, personal computing and mobile devices.

The WirelessHD specification has been architected and optimized for wireless display connectivity, achieving in its first generation implementation high-speed rates from 2 Gbps to 5 Gbps for the CE, PC, and portable device segments. Its core technology promotes theoretical data rates as high as 20 Gbps, permitting it to scale to higher resolutions, color depth, and range.

LG Electronics Inc., Matsushita Electric Industrial Co., Ltd. (Panasonic), NEC Corporation, SAMSUNG ELECTRONICS CO., LTD, SiBEAM, Inc., Sony Corporation and Toshiba Corporation, formed a consortium to define a specification for the next generation wireless digital network interface specification for consumer electronics products. It is easily seen that these promoter companies have historically been responsible for creating the world’s most successful consumer electronics standards. Based on that experience, this group is promoting rapid adoption, standardization and multi-vendor interoperability of WirelessHD technology worldwide.

WirelessHD Architecture Overview

The WirelessHD specification defines a wireless video area network (WVAN) for the connection of CE, PCs and portable devices. A key attribute of the WirelessHD system is its ability to support the wireless transport of a lossless FullHD 1080p/60 A/V stream with a high quality of service (QoS) within a room at distances of up to ten meters. Wireless data throughput at distances of the order of tens of meters requires a large allocation of frequency spectrum. A large amount of unrestricted spectrum is available in many countries around the 60 GHz band. The high throughput requires effective transmit power greater than 10 Watts. A side effect of such a high-throughput connection, however, is that it would normally be highly directional, requiring clear line-of-sight between devices. WirelessHD has overcome this limitation by defining a breakthrough protocol for directional connections that adapt very rapidly in response to changes in the environment. This is accomplished by employing smart antenna technology that dynamically steers the transmitting antenna beam while at the same time focusing the receiver antenna in the direction of the incoming power from the transmitter.

USB 3.0 : 10 times faster!

2010-05-03T21:56:00.000-07:00

Every motherboard manufacturer is now coming up with USB 3.0 compliant boards. We have seen market leaders like Gigabyte and Asus launch their boards with USB 3.0 ports. So whats in store as far as we, consumers have to look out for? USB 3.0 is the next major revision of the ubiquitous Universal Serial Bus.
Isn't USB 2.0 Good enough?
Well, the answer is contextual! USB 2.0 indeed provides sufficient bandwidth for many applications and for a variety of devices and hubs. As has been the trend in the past, with today's ever increasing demands placed on data transfers 480Mbps is not really fast! The theoretical maximum throughput of 480 Mbps is never achieved by any USB 2.0 product. The need for this higher performance connection between the host and the peripheral is addressed by the USB 3.0
USB 3.0
USB 3 as such is similar to its predecessors, that is its a cable bus supporting data transfers. USB 3.0 plugs will be backwards compatible with USB 2.0 devices and plugs, respectively. However, a new receptacle has been created "USB 3.0 Standard-B" which can only accept a USB 3.0 Standard-B device plug. USB 3.0 achieves higher performance using an additional physical bus that is added in parallel with the existing USB 2.0 bus. So instead of 4 wires (power, ground, and a pair for differential data as in USB 2.0), USB 3.0 has 4 more for two pairs of differential signals (receive and transmit). The extra two pairs support the Super-speed USB bandwidth requirements. The signaling method also has been changed. USB 3.0 utilizes a bi-directional data interface. The "Super-speed" bus provides a transfer rate of 5.0 Gbps. The raw throughput claimed is 4 Gbps. So one can expect USB 3.0 to achieve around 3.2 Gbps (400 MBps) including all overheads.

USB 3.0 Super-speed can handle more power over its cable. The voltage a device is required to have has dropped from 4.4V to 4V. No limits has been specified for the length a USB 3.0 cable can have but longer cables will affect the speeds that can be achieved. Also, USB 3.0 Super-Speed creates a communication pipeline with host and each device or a "host-directed protocol" instead of broadcasting packets to all devices as in USB 2.0.

Operating systems supporting USB 3.0
Microsoft had announced that Windows 7 would have USB 3.0 support. We cannot expect it to happen in the current releases though. Once they successfully integrate USB 3.0 int Win7.0, we can expect support for older version of windows too. Super-speed support for Windows XP is unknown at this point.

Linux will most definitely support USB 3.0 once the xHCI specification is made public. The open source society will definitely strive to keep u with the technology! The Linux USB stack would have to be updated to add support for USB 3.0 according to the specification.

Apple has been silent on the issue of Super-speed USB support in MacOS X. Apple will have to provide the support if the rest of the industry adopts this interface standard.

Overall, USB 3.0 O/S support will come in stages and phases, but it will take time.

Four thirds : New Camera Standard

2010-04-19T21:31:00.000-07:00

Your next digital camera may adhere to a standard you've never heard of: Four Thirds! The Four Thirds Specification defines the standard diagonal length of the 4/3-type image sensor, suitable image circle of lens and an interface between lens and body. The intention is to make possible compatibility among camera bodies and lenses regardless of manufacturer or model.

History
The recent trend is to use image sensors on 135 film single-lens-reflex cameras. However, the optical design of the current interchangeable lens for the 135 film camera is not perfect for the image sensor. Unlike older SLR systems, Four Thirds has been designed from the ground up to be entirely digital. The Four Thirds Specification proposes an optimum image sensor size and specifications of interchangeable lens suitable for camera in the digital age.

Four Thirds system
The purpose of the Four Thirds System Specification (Four Thirds Specification) is to standardize an interchangeable lens system for digital cameras. The Four Thirds Specification provides users reliable and extensive variations of products suitable for digital age. Four Thirds system is a standard created by Olympus and Kodak for digital single-lens reflex camera (DSLR) design and development.The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different manufacturers. Even though it is claimed to be an open standard,it is accessible to only to companies under a non-disclosure agreement.

Size of the Sensor, Aspect ratios
The standard diagonal length of the sensor is 21.63 mm. It is half that of 35-mm film format (36 mm x 24 mm) and is a suitable format for use in digital cameras. The image circle of the interchangeable lens is specified based on this diagonal length. The image aspect ration is 4:3 which sets apart the Four Thirds system from other DSLR systems, which stick to the 3:2 aspect ratio of the traditional 35 mm format.
The focal length is about a half that of a 135 film camera lens assuming the same angle of view.

Any Lens Any Body !
The system ensures the functionality of lens interface, focus, exposure control, etc. between lens and body made by different manufacturers and models to meet the demands of various users.

Lens resolution & cornershading
Conventional lenses with did not have very high resolving power. Digital sensors demand a very high resolution, way beyond the 10 microns usually offered by conventional lenses. Modern digital cameras have a pixel pitch of order of 5 or 6 microns or less, overlapping and quality losses result. This puts a serious limitation on the performance of the sensors. The problem is exacerbated with a greater number of pixels and a smaller sensor size. All lenses designed for the Four Thirds standard ensure the image sensor is not wanting. The ultra-fine resolution attained through special manufacturing processes guarantees full sensor performance. Telecentric optical path means that light hitting the sensor is traveling perpendicular to the sensor, resulting in brighter corners, and most importantly improved off-center resolution, particularly on wide angle lenses.

Advantages

The smaller sensor size makes implies smaller and lighter camera bodies and lenses.
The flange focal distance is significantly shorter, hence lenses for many other SLR types can be used with Four Thirds cameras with simple mechanical adapter rings.
A smaller sensor makes it easier to achieve a deeper depth-of-field, when needed, reducing the risk of photos that are out of focus.

Disadvantages

Small sensors results in compromises in image quality. Less sensor area limits the ability to collect light and results in lower signal-to-noise ratio.
Because of the higher crop factor, an image shot at a given relative aperture and angle of view will have more depth of field on Four Thirds. This results in less control over depth of field, compared to larger formats.

Micro Four Thirds
The Micro Four Thirds system is also a standard created by Olympus and Panasonic.The system provides a standard for design of compatible interchangeable lenses and compact cameras by different manufacturers adhering to the system. Micro Four Thirds shares the image sensor size and specification with the established Four Thirds system. Unlike Four Thirds, Micro Four Thirds does not provide space for a mirror and a pentaprism, allowing smaller bodies to be designed. The standard supports use of Four Thirds lenses on Micro Four Thirds camera bodies using an adapter, but Micro Four Thirds lenses cannot be used on Four Thirds bodies.

CUDA - The End of CPUs?

2010-04-07T00:03:00.000-07:00

CUDA is NVIDIA’s parallel computing architecture that enables dramatic increases in computing performance by harnessing the power of the GPU (graphics processing unit).CUDA is an acronym for Compute Unified Device Architecture. CUDA computing engine in NVIDIA graphics processing units or GPUs is accessible to software developers through industry standard programming languages. Programmers can use 'C for CUDA' (basically C with NVIDIA extensions), compiled through a special compiler, to code algorithms for execution on the GPU. Millions of CUDA-enabled GPUs have been sold to date, with users ranging from software developers to scientists and researchers.

What lead to CUDA?
CPUs are normally designed to get maximum performance from a stream of instructions, which operates on diverse data. Memory accesses are random and branching etc. happens frequently. Keeping this in mind designers worked hard to extract more parallelism of instructions. Speeding up essentially meant launching as many instructions as possible in parallel. Superscalar execution, out-of-order execution of instructions are all oriente towards this goal. The problem here is that there is a certain limit to the parallelism that can be extracted out of a sequential stream of instructions. Blindly increasing the number of calculating units also does not help the cause.

The GPUs are designed for a simpler job. Take a group of polygons, generate a group of pixels etc. The polygons and pixels are independent of each other, and so can be processed by parallel units. That means that a GPU can afford to have a large number of calculating units which, unlike those of a CPU, will actually be used. Memory access in a GPU is extremely coherent – when a texel is read, a few cycles later the neighboring texel will be read, and when a pixel is written, a few cycles later a neighboring pixel will be written. By organizing memory intelligently, performance comes close to the theoretical bandwidth. That means that a GPU, unlike a CPU, doesn’t need an enormous cache, since its role is principally to accelerate texturing operations. GPUs are designed specifically for graphics and thus are very restrictive in terms of operations and programming. Because of their nature, GPUs are only effective at tackling problems that can be solved using stream processing and the hardware can only be used in certain ways.
This lead to the new concept of GP GPUs.

GP GPU
General-purpose computing on graphics processing units is simply using a GPU, to perform computation in applications traditionally handled by the CPU. It is made possible by the addition of programmable stages and higher precision arithmetic to the rendering pipelines, which allows software developers to use stream processing on non-graphics data.The term GPGPU was coined and GPGPU.org was founded by Mark Harris in 2002 when he recognized an early trend of using GPUs for non-graphics applications.

CUDA Advantage
Several advantages that CUDA has are like

The code can read from arbitrary addresses in memory.

CUDA exposes a fast shared memory region which can be used as a user-managed cache, enabling higher bandwidths.

Faster downloads and readbacks to and from the GPU

Full support for integer and bitwise operations, including integer texture lookups.

A scalable programming model allows the CUDA architecture to span a wide market range

The Architecture
Nvidia’s Shader Core is made up of several clusters caleed Texture Processor Clusters. Each cluster is made up of a texture unit and two streaming multiprocessors. These processors consist of a front end that reads/decodes and launches instructions and a backend made up of a group of eight calculating units and two SFUs (Super Function Units) where the instructions are executed in SIMD fashion: The same instruction is applied to all the threads in the warp. At each cycle, a warp ready for execution is selected by the front end, which launches execution of an instruction. To apply the instruction to all 32 threads in the warp, the backend will take four cycles, but since it operates at double the frequency of the front end, from its point of view only two cycles will be executed. So, to avoid having the front end remain unused for one cycle and to maximize the use of the hardware, the ideal is to alternate types of instructions every cycle – a classic instruction for one cycle and an SFU instruction for the other.Each multiprocessor has a small memory area called Shared Memory with a size of 16 KB per multiprocessor. This is not a cache memory – the programmer has a free hand in its management.

Future CUDA architectures
The next generation CUDA architecture "Fermi" is designed from the ground up to natively support more programming languages such as C++. It is expected to have eight times the peak double-precision floating-point performance compared to Nvidia's previous-generation Tesla GPUs.

Todays biggest trend in Phone systems

2010-03-23T21:31:00.000-07:00

Buying a new phone system can be an exercise in sorting through acronyms and learning new technologies. When you’re grinding through those types of details, it can be tough to keep the big picture in mind. To help you out, buyerzone.com, a website recently interviewed several phone system dealers to find out what the biggest trends in telecommunications purchasing are right now. Read the summary here.

Buyer be aware: today’s biggest trends in phone systems

Another article to get you the details on how you can be a smarter buyer by avoiding some common mistakes is detailed in this post by buyerzone.com.

Phone system dealers share their secrets on saving money and avoiding common mistakes

LTE & WiMax : some facts

2010-02-12T00:01:00.000-08:00

The communication industry has been formulating new standards to efficiently deliver high speed broadband mobile access in a single air interface and network architecture at low cost to operators and end users. Two standards, IEEE 802.16 (WiMAX) and 3GPP LTE are leading the pack towards forming the next-generation of mobile network standards. Here is a brief overview of the similarities and dissimilarities.

WiMaX
The WiMAX (IEEE 802.16 standard) comes from IEEE family of protocols and extends the wireless access from the Local Area Network (typically based on the IEEE 802.11 standard) to Metropolitan Area Networks (MAN) and Wide Area Networks (WAN). It uses a new physical layer radio access technology called OFDMA (Orthogonal Frequency Division Multiple Access) for uplink and downlink. While the initial versions 802.16-2004 focused on fixed and nomadic access, the later version 802.16-2005, an
amendment to 802.16-2004 include many new features and functionalities needed to support enhanced QoS and high mobility broadband services at speeds greater than 120 Km/h. The 802.16-2004 is also called 802.16d and is referred to as fixed WiMAX while the 802.16-2005 is referred to as 802.16e or Mobile WiMAX. The Mobile WiMAX uses an all IP backbone with uplink and downlink peak data rate capabilities of upto 75 Mbps depending on the antenna configuration and modulation, practicable to 10 Mbps within a 6 miles (10 Km) radius. The earliest iterations of WiMAX was approved with the TDMA TDD and FDD with line of sight (LOS) propagation across the 10 to 66 GHz frequency range which was later expanded to include operation in the 2 to 11GHz range with non line of sight (NLOS) capability using the robust OFDMA PHY layer with sub-channelization allowing dynamic allocation of time and frequency resources
to multiple users. The 802.16m (Mobile WiMAX Release 2) will address the next-generation systems with an aim for optimizations for improved interworking and coexistence with other access technologies such as 3G cellular systems, WiFi and Bluetooth and enhance the peak rates to 4G standards set by the ITU under ‘IMT-Advanced’ umbrella which calls for data rates of 100 Mbps for high mobility and 1 Gbps for fixed/nomadic wireless access. Bus as of today it is LTE that the ITU has chosen as the IMT-advanced standard.

LTE
The LTE, on the other hand evolves from the Third-generation technology which is based on WCDMA and defines the long term evolution of the 3GPP UMTS/HSPA cellular technology. The specifications of these efforts are formally known as the evolved UMTS terrestrial radio access (E-UTRA) and evolved UMTS terrestrial radio access network (E-UTRAN), commonly referred to by the 3GPP project LTE. The first
version of LTE is documented in Release 8 of the 3GPP specifications. It defines a new physical layer radio access technology based on the same OFDMA for the downlink, similar in concept to the PHY layer of Mobile WiMAX, and uses SC-FDMA (single Carrier Frequency Division Multiple Access) for the uplink. LTE supports high performance mobile access functional upto 350Km/h with 500Km/h under consideration. Peak data rates range from 100 to 326.4Mbps on the downlink and 50 to 86.4 Mbps on the uplink depending on the antenna configuration and modulation depth. The LTE also targets to achieve the data rates set by the 4G ‘IMT-Advanced’ standard. The development of LTE interface is linked closely with the 3GPP system architecture evolution (SAE) which defines the overall system architecture and Evolved Packet Core (EPC). The LTE aims to provide an all IP backbone with reduction in cost per bit, better service provisioning, flexibility in use of new and existing frequency bands, simple network architecture
with open interfaces, and lower power consumption.

Evolution of Medianets

2010-01-11T21:01:00.000-08:00

Technologies to deliver real time multimedia is evolving and evolving fast. These technologies aim at delivery of video content over IP and is based on Next-Generation-Networks (NGN). The architectures take advantage of the developments and standardization that has happened in the areas of IPTV and cable networks. Thes eeffectively create a 'medianet' which is optimized to deliver on demand services to any and many devices, over any of the wired or wireless networks.

IPTV
IPTV technology is part of a new breed of services designed to facilitate access to video entertainment. It provides access to digital TV over the IP transport medium from a head-end device to the end user’s TV set-top box (STB). Most service providers use a dedicated transport network to support IPTV. IPTV system gathers content from a variety of sources including network feeds, stored media, communication links and live studio sources. Broadcast information coming from an antenna or a satellite dish at the national head-end is mainly distributed using MPEG-2 multiprogram transport stream (or MPTS) to the respective service nodes. More efficient compression algorithms which consume lesser bandwidths such as H.264 (MPEG-4 Part 10) or the Society of Motion Picture and Television Engineers (SMPTE) 421M (also known as VC-1) are making their way to the markets.. The introduction of the new MPEG4 part 10 codec (also known as advanced video codec [AVC]) over the past few years has generated interest for future IPTV deployments.

The enormous growth and interest in IPTV services over the past few years is a trend that is anticipated to continue over the coming years. The implications of these advances on IPTV services are that the bandwidth savings will enable more or higher-quality TV content to be made available over the typically bandwidth-constrained access links, whether it is wireline, wireless, or cable.

Getting the Bandwidth
We must also consider the whole area of bandwidth capacity evolution and how it is managed to ensure IPTV QoS/QoE requirements. Optical transport infrastructures will become the technology of choice for the last-mile video content delivery. The advances in cable or DSL access technologies, and in wireless transport technologies such as Long Term Evolution (LTE) or WiMAX have the capabilities to deliver the requires QoS. However, optical fiber transport technologies, such as Ethernet PON (EPON) and Gigabit PON (GPON) or direct FTTH, clearly have the requisite bandwidth capabilities to deliver multiple channels of HDTV and VoD content with high QoE that consumers demand.As the 4G wireless networks evolve, the demand for mobile video content for handset is expected to grow. There are other major technology trends that are likely to play increasing roles in the evolution of cable networks. One such trend is the popularity of digital TV content.

Future of Medianet
The medianet is expected to enable video services and technology evolution to have the potential to transform consumer experience by utilising the IP NGN into a data-sensitive network that manages scale and complexity. Medianet also fits in well with emerging trends in media buying. As advertisers seek to make themselves heard over the cacophony of a million voices, all competing for the consumer's attention, they are no longer willing to settle for standard advertising measures. Medianet promises a new generation of exceptional, reliable, personalized, rich media experiences anywhere, anytime, and to any device.

Wireless Mesh Networks

2010-01-04T21:05:00.000-08:00

How often have you become tired of your slow wireless Internet and network connections that get bogged down? When too many uses try to log on, the connection becomes slow and sometimes closes down automatically for no reason. Engineers have found a better way to wirelessly connect to internet, where the more users there are the better it works. It's called Wireless Mesh technology. Wireless mesh networks have steadily emerged over the past few years as the latest and greatest method for utilizing wireless broadband as a means for high-speed data connectivity.

WMN
A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. Wireless mesh networks were originally developed for military applications and are typical of mesh architectures. Over the past decade the size, cost, and power requirements of radios has declined, enabling more radios to be included within each device acting as a mesh node. Wireless mesh networks are effective in sharing Internet connectivity because the more nodes that are installed, the further the signal can travel. And the more nodes you have, the stronger and faster the Internet connection becomes for the user. It is often seen as an extension of Ad-hoc wireless networks. A wireless ad hoc network is a decentralized wireless network.

Architecture
The Wireless network is basically a series of linked transmitters and receivers. Mesh architecture sustains signal strength by breaking longer distances into shorter hops. The intermediate nodes do the signal enhancement as well as routing. Nodes are programmed with software that tells them how to interact within the larger network. Information travels across the network from point A to point B by hopping wirelessly from one mesh node to the next. In a wireless mesh network, only one node needs to be physically wired to a network connection like a DSL Internet modem. That one wired node then shares its Internet connection wirelessly with all other nodes in its vicinity. Those nodes then share the connection wirelessly with the nodes closest to them. The more nodes, the further the connection spreads, creating a wireless "cloud of connectivity" that can serve a small office or a city of millions. This type of infrastructure can be decentralized (with no central server) or centrally managed. The topology of a mesh network is also more reliable, as each node is connected to several other nodes. If one node drops out of the network, due to hardware failure or any other reason, its neighbors can find another route using a routing protocol.

Challenges
The evolution of wireless mesh equipment has improved dramatically since its inception. The emergence of the 4.9 GHz Public Safety band gives yet another option for meshing radios. Nearly all mesh networks require a PtMP (or fiber if available) to backhaul wireless mesh traffic. The emergence of OFDM now allows for up to 22 Mbps of throughput capacity that can be injected into the wireless mesh by converting a node into a gateway location.

While these technologies continue to push more bandwidth through the same spectrum, the costs continue to come down. Both Proxim and Motorola have cost effective mesh radios.
Additionally, the evolution of convergence promises greater interoperability among WiFi and cellular networks. “Convergence” refers to networks that will use the best available network to send/receive VoIP traffic. While it is still a couple of years away, the concept of sending VoIP traffic over a WiFi network in order to limit cell minutes (thereby reducing your bill) is very attractive to consumers.

HSPA - Overview

2009-12-15T06:06:00.000-08:00

We see that a lot of 3G enabled handsets are available in the market now. What exactly is meant by 3G enabled? If we look at the specs provided by the manufacturers, we see that all of them support the HSPA. So we shall see what is HSPA.

HSPA
The first step in the evolution of WCDMA radio access is the introduction of High-Speed Downlink Packet Access (HSDPA). HSDPA brings further enhancements to the provisioning of packet-data services in WCDMA, both in terms of system and end-user performance.HSDPA and Enhanced Uplink are often jointly referred to as High-Speed Packet Access (HSPA). To achieve high data rates and low delays while maintaining good coverage HSPA introduces several techniques such as higher order modulation, fast (channel-dependent) scheduling and rate control, and fast hybrid ARQ with soft combining.HSPA provides downlink and uplink data rates up to approximately 14 and 5.7 Mbps, respectively, reduced round trip times and improved capacity.

WCDMA
Wideband CDMA is a versatile and highly flexible radio interface that can be configured to meet the requirements from a large number of services.The basis for the physical layer of WCDMA is spreading of the data to be transmitted to the chip rate, which equals 3.84 Mchip/s. It is also responsible for coding, transport-channel multiplexing, and modulation of the radio-frequency
carrier. This technology is similar to the existing CDMA system but only in the physical layer. If we look at the specs of the 3G handsets we can indeed verify that these handsets support this technology conforming to the GSM standard.

The HSPA Evolution continues to add new technical features, and at the same time be able to serve the already existing terminals. This is the successful strategy of GSM that have added new features constantly since the introduction.

Characteristics
Shared-Channel transmission : A key characteristic of HSDPA is the use of Shared-Channel transmission. This implies that a certain fraction of the total downlink radio resources available within a cell, channelization codes and transmission power in case of WCDMA, is seen as a common resource that is dynamically shared between users, primarily in the time domain.

Channel-dependent scheduling : Scheduling controls to which user the shared-channel transmission is directed at a given time instant. The radio-channel conditions are taken into account in the scheduling decision,resulting in a significant increase in capacity.

Rate control and higher-order modulation: Rate control is implemented by dynamically adjusting the channel coding rate as well as dynamically selecting between QPSK and 16QAM modulation. Higher-order modulation such as 16QAM allows for higher bandwidth utilization than QPSK, but requires higher received signal to noise ratios.

Hybrid ARQ with soft combining: Hybrid ARQ with soft combining allows the terminal to request retransmission of erroneously received packets, effectively fine-tuning the code rate and compensating for errors made by the link-adaptation mechanism.Soft combining implies that the terminal does not discard information in case a transport block is in error, but combines the information from previous transmission attempts with the current retransmission to increase the probability of successful decoding.

Deployment and further evolution
The HSPA has to coexist and provide inter-working with other radio access technologies such as GSM. HSPA is also subject to a continuous evolution. Through the use of multiple antennas at both the uplink and downlink, further increase the peak data rates is possible. The use of Continuous Packet Connectivity provides an ‘ always-on ’ experience for the end user.

AirPod - Cleaner, Greener Future!

2009-12-07T20:47:00.000-08:00

Airpod is a 220-kg car with a composite shell and a brand new path-breaking energy supply: 80 kg of air compressed to 350 times sea-level atmospheric pressure. Engine of this tiny three-seater converts that air into mechanical energy. The current version has a top speed of 45 kilometers per hour.

This future urban transport is the product of Motor Development International (MDI), a company registered in Luxembourg. This technology hopes to find mass appeal in the city-car category, an automotive segment of small, efficient cars well suited for crowded European and Asian cities and not meant for long-haul trips.

Eco-friendly
The AirPod, as the company claims , can tank up in just 2 or 3 minutes using very small amount of precious electricity to provide some 220 km (137 miles) of city driving. It has no batteries to wear out and replace and hence is eco-friendly in that aspect too. Energy is stored in a long-lasting pressure tank made of carbon fiber making the AirPod cheaper, more practical, and cleaner than a comparable electric vehicle (EV).

Pneumatic Propulsion
This system used to be high tech in the 19th century. Jack hammers are made to work on this principle only. But for vehicles this is considered unusable. The law of thermo dynamics makes it a considerable challenge. The molecules of oxygen, nitrogen, and other gases in air give off heat when compressed, which is a loss of energy up front. Compress it quickly, before the heat can dissipate into the surroundings, and the losses rise further. And the trouble only mounts when this compressed gas is later released from the tank. The same molecules cool when they expand. Expand the gas slowly, and the pneumatic equipment can stay warm by reabsorbing energy from the atmosphere. But power-hungry vehicles must expand the gas quickly, so they are subject to extreme cooling, which hampers the engine or, at worst, freezes air-feed lines. The AirPods 220L tank is big but it carries energy which is a little more than a liter of gasoline. The engine has to be very efficient to make the most of this energy.

The engine
The engine uses two linked cylinders. compressed air flows into the smaller one at a constant pressure. When the smaller piston bottoms out, the intake is closed and air expands. The air now flows into the larger cylinder . Both the pistons move to exhaust the expanded air. The cycle thus restarts.

Alternate ideas
Although pneumatic engines are problematic for vehicular propulsion, storing compressed air on board a car can boost the efficiency of a normal combustion engine enormously. The idea is to use the engine to compress a small volume of air during braking, then feed that high-pressure air back to the cylinders during acceleration to increase the amount of fuel they can burn, sending more power to the wheels.

Is this the future?
No independent testing laboratory has assessed the AirPod’s performance. And while deals over the past three years with India’s Tata Motors and Paris based AirFrance have bolstered MDI’s credibility, it remains
tough to find an automotive engineer who buys into the company’s vision.

WAVE : For vehicle networking

2009-08-18T02:29:00.000-07:00

An emergency-response vehicle rapidly approaches an intersection with a four-way stop. As it approaches the intersection, the vehicle sends a message to similar devices located in all nearby vehicles to pre-empt the crossroad. The onboard computer of any of the receiving vehicles first alerts the driver about the emergency, and then, if necessary, autonomously slows down the vehicle to avoid a collision. Does this sound like a Hi-fi movie part? Well this could be happening in the next couple of years. Intelligent transportation systems have been under development since early 1990s.The rationale behind the concept is to automate the interactions among vehicles and infrastructure to achieve high levels of security, comfort, and efficiency. The IEEE has developed a system architecture known as WAVE to provide wireless access in vehicular environments.

WAVE
In 2004, an IEEE task group (task group p) started developing an amendment to the 802.11 standard to include vehicular environments. Simultaneously, another IEEE team (working group 1609) undertook the task of developing specifications to cover additional layers. The standards put forward by these two
are called Wireless Access in Vehicular Environments (WAVE). A WAVE system consists of entities called Roadside units (RSUs) and On board units (OBUs).RSUs are usually installed in light poles, traffic lights, road signs etc. whereas OBUs are mounted in vehicles.

Protocols used
The WAVE architecture supports two protocol stacks - IPv6 and WAVE Short Message Protocol (WSMP) - which use the same physical and data-link layers. These two help in accomodating the conventional protocols as well. By default, WAVE units operate independently and exchange information over a fixed radio channel known as the control channel (CCH).The WAVE PHY and MAC layers are based on IEEE 802.11a, and their corresponding standard is IEEE 802.11p.

Services offered
Functionally WAVE provides two networking services:
• Data-plane services
The main function is to carry traffic. This serves to accommodate high-priority, time-sensitive communications (through WSMP), as well as less demanding ones through UDP/TCP/IP
• Management-plane services:
The main functions are system configuration and maintenance, which include application registration, WBSS management, channel usage monitoring etc.

Other Aspects
WAVE applications face unique safety constraints because of their wide range of operation. For example, safety applications are time critical; therefore, the processing and
bandwidth overhead must be kept to a minimum. WAVE must protect messages from eavesdropping, spoofing, alterations, and replay. Cryptographic mechanisms provide most of these security requirements. The WAVE architecture is built on the IEEE 802.11 standard, which gives it the backing of a sizable community of wireless experts. New research and development contributions are still going on.

Already, experimental networks have been implemented in different parts of USA to display and test applications for collision avoidance, traffic management, emergency response systems etc.

SQL Transactions

2009-07-25T22:20:00.000-07:00

A database transaction is a larger unit that frames multiple SQL statements. SQL-Transaction Statements control transactions in database access. A transaction ensures that the action of the framed statements is atomic with respect to recovery. Atomic means that all the work in the transaction is treated as a single unit. Just have an overview of the SQL transactions... !

The primary use of transactions is to ensure database's data consistency. Transactions help ensure that the database's data remains consistent and are mostly used in cases where we need to group a set of operations(INSERT/UPDATE/DELETE) such that the entire set works as a single logical entity. Either all of them fail or all succeed. There is no 'medieval' state. Transactions treat the operations enclosed as a single atomic operation. We can rollback the transaction in the face of an error and undo any changes made since the start of the exception. While INSERT, UPDATE, and DELETE statements are the most granular operations for modifying a database's underlying data, at times we want to treat multiple INSERT, UPDATE, and/or DELETE statements as one atomic operation. That is, in certain situations, rather than having each INSERT, UPDATE, and DELETE statement stand on its own, we want the set of statements to be, together, an indivisible unit. When issuing this set of statements we want either the entire set of statements to succeed, or all to fail - there should be no 'in-between' state.

In day to day life a typical example of Transaction usage would be : Suppose person A wants to transfer and amount to person B's account.Then the amount should be debited from A's account and credited in B's account. Both these operations should be treated as an entity. Either both should happen or none.

The Common Steps of a Transaction
When using transactions you'll typically use the following sequence of steps:

1. Indicate that you want to start the transaction. All commands from this point forward are part of the logical, atomic operation.
2. Issue the discrete commands - the INSERT, UPDATE, and DELETEs that make up your transaction.
3. If any of these commands cause an error, rollback the transaction. Rolling back a transaction has the effect of undoing the effects of all previous statements in the transaction.
4. If all steps succeed, commit the transaction. This persists the changes made throughout the transaction to the database.

First things first

We need to indicate that a transaction should begin. This is done, conveniently enough, with the T-SQL command BEGIN TRANSACTION. Following that, you'll issue the set of statements that you want to be part of the transaction, which will typically include INSERTs, UPDATEs, and/or DELETEs. Transactions ensure that a set of modifying statements are atomic, namely that either all steps succeed or all steps fail. Transactions guarantee atomicity across query errors - such as trying to delete a record that cannot be deleted due to a foreign key constraint, or attempting to insert a string value into a numeric field in a database table - as well as catastrophic errors, such as power failures, hard drive crashes, and so on.
Transactions group a set of tasks into a single execution unit. Each transaction begins with a specific task and ends when all the tasks in the group successfully complete. If any of the tasks fails, the transaction fails. Therefore, a transaction has only two results: success or failure. Incomplete steps result in the failure of the transaction.

Lots of information is available on transactions.

LTE vs WiMAX

2009-06-10T21:25:00.000-07:00

A long-term battle is brewing between two emerging high-speed wireless technologies, WiMax and Long Term Evolution (LTE). Each would more than quadruple existing wireless wide-area access speeds for users. Both are 4G technologies designed to move data rather than voice. Both are IP networks based on OFDM technology.

The two technologies are somewhat alike in the way they transmit signals and even in their network speeds. The meaningful differences have more to do with politics - specifically, which carriers will offer which technology.

The Genesis
WiMax is based on a IEEE standard (802.16).It’s an open standard that was debated by a large community of engineers before getting ratified.The level of openness means WiMax equipment is standard and therefore cheaper to buy!

LTE or Long Term Evolution is a 4G wireless technology and is considered the next in line in the GSM evolution path after UMTS/HSPDA 3G technologies. LTE is espoused and standardized via the 3GPP or 3rd Generation Partnership Project members. 3GPP is a global telecommunications consortium having members in most GSM dominant countries.

LTE vs WiMAX
WiMAX emerged from the WiFi IP paradigm, whereas LTE is a result of the classic GSM technology path. LTE is behind in the race to 4G with WiMAX getting an early lead with several operators in Asia opting to go with WiMAX in the near term. So where WiMAX has a speed to market advantage, LTE has massive adoption and GSM parenthood to back it up.

LTE will take time to roll out, with deployments reaching mass adoption by 2012 . WiMax is out now, and more networks should be available later this year.

Speed offered
LTE will be faster than the current generation of WiMax as per well known text books, but 802.16m that should be ratified this year, offers similar speeds.The speeds expected by both LTE and WiMax are hard to nail down primarily because the technologies are just rolling out. But many factors will have to be taken into consideration.Speed to an end user is also dependent on how many users are connected to a cell tower, how far away they are, what frequency is used, the processing power of the user's device, and other factors.

Who will win?
For end users, the current debate over WiMax vs. LTE is largely theoretical but is nonetheless important.Analysts see a clear dominance by LTE in a few years, since so many carriers are bound to adopt it. However, that won't serve every user or every company. It is still going to be a combination of technologies and developers, WiMax may be one of those; but not the only one!!!

Authentication Protocols

2009-05-06T01:26:00.000-07:00

All networks rely on some kind of protocols for effective, faster and safer communication. When it comes to safe communication, cryptographic algorithms are just one piece of the big picture. Before two participants establish a secure channel between themselves (may be using an algorithm such as DES to encrypt messages), they will have to establish that the other participant is indeed who he or she claims to be.This is the problem of authentication.

Authentication
Authentication is the technique by which a process verifies that its communication partner is who it is supposed to be and not an imposter. Verifying the identity of a remote process in the face of a malicious, active intruder is surprisingly difficult and requires complex protocols based on cryptography.

Authorization with Authentication
Some people confuse authorization with authentication. Authentication deals with the question of whether you are actually communicating with a specific process. Authorization is concerned with what that process is permitted to do. It is during the process of authentication that the two participants establish the session key that is going to be used to ensure privacy during subsequent communication. There are several methods that make this happen.

Based on a Shared Key
Client and Server share a secret key. This protocol is based on the simple principle: one party sends a random number to the other, who then transforms it in a special way and then returns the result. Such protocols are called challenge-response protocols. The shared-key authentication protocol follows the pattern given:
In message 1, Client sends her identity, to Server in a way that Server understands. In order to know whether this message came from client,he chooses a "challenge", a large random number, and sends it back in plain text. Random numbers used just once in challenge-response protocols like this one are called "nonces". Client then encrypts the message with the shared key and sends the cipher text back. When Server sees this message, it immediately knows that it came from the true client because none else could not have generated it using the shared key. Furthermore, since random number was chosen randomly from a large space , it is very unlikely that an intruder would have seen it and its response from an earlier session.

The truth is that even this can fail if the intruder opens multiple connections with the server and there are ways of hacking it! So designing an authentication protocol is not easy as it sounds!

Authentication Using a Key Distribution Center
Here the scenario is that the two participants know nothing about each other, but both trust a third party. This third party is called an "authentication server". There are many different variations of this protocol.
The participant A ﬁrst sends a message to server S that identiﬁes both itself and B. The server then generates a time stamp T, a lifetime L, and a new session key K. Participants A and B will have to go back to server S to get a new session key when the time stamp expires. The idea here is to limit the vulnerability of any one session key. Server S then replies to A with a two-part message. The ﬁrst part encrypts the three values T, L, and K, along with the identiﬁer for participant B, using the key that the server shares with A. The second part encrypts the three values T, L, and K, along with participant A’s identiﬁer, but this time using the key that the server shares with B. Clearly, when A receives this message, it will be able to decrypt the ﬁrst
part but not the second part. A simply passes this second part on to B, along with the encryption of A and T using the new session key K.B decrypts the part of the message from A that was originally encrypted by S, and recovers T, K, and A. It uses K to decrypt the half of the message encryptedby A and, upon seeing that A and T are consistent in the two halves of the message,replies with a message that encrypts T + 1 using the new session key K.

Authentication Using Kerberos
An authentication protocol used in many real systems (including Windows 2000) is Kerberos. It is named for a multi-headed dog in Greek mythology that used to guard the entrance to Hades. Kerberos is a trusted third-party authentication service based on the model presented by Needham and Schroeder.It is trusted in the sense that each of its clients believes Kerberos' judgment as to the identity of each of its other clients to be accurate. Kerberos provides three distinct levels of protection. The application programmer determines which is appropriate, according to the requirements of the application. For example, some applications require only that authenticity be established at the initiation of a network connection, and can assume that further messages from a given network address originate from the authenticated party. When a user requests a service, her/his identity must be established. To do this, a ticket is presented to the server, along with proof that the ticket was originally issued to the user, not stolen. There are three phases to authentication through Kerberos. In the first phase, the user obtains credentials to be used to request access to other services. In the second phase, the user requests authentication for a specific service. In the final phase, the user presents those credentials to the end server.

There are a number of issues and open problems associated with the Kerberos authentication mechanism. Among the issues are how to decide the correct lifetime for a ticket, how to allow proxies, and how to guarantee workstation integrity.

Authentication Using Public-Key Cryptography
Mutual authentication can also be done using public-key cryptography. The public key protocol is a useful one because the two sides need not share a secret key; they only need to know the other side’s public key.

A needs to get B's public key. A asks the directory server that hands out certificates for public keys, for B's public keys. The reply is a certificate containing B's public key. When A verifies that the signature is correct, it sends B a message containing its identity and a nonce. When B receives B then sends A a message containing A's message, his own nonce, and a proposed session key. A receives the message and decrypts it using its private key. A sees the random number it send to B in it. A agrees to the session by sending back a message. When B sees the nonce it send to A encrypted with the session key just generated, the session is really established.

Challenges
Public key cryptography is an extremely powerful technology, but it depends on the distribution of public keys. The problem of getting keys to people who need them in such a way that they can be sure that the key is legitimate turns out to be a challenging problem.The basic solution to the problem relies on the use of digital certiﬁcates. These are documents that bind a principal to a public key. Certificates are signed by a trusted authority or by someone approved by a trusted authority.

Digital signatures have a potential weakness due to lazy users. In e-commerce transactions, a contract might be drawn up and the user asked to sign its SHA-1 hash. If the user does not actually verify that the contract and hash correspond, the user may inadvertently sign a different contract!

The moral of the story is that authentication is not as safe as you think it is! Safe browsing!

Webcrawlers

2008-11-29T19:43:00.000-08:00

What is a web crawler?
A web crawler is a relatively simple, automated program, or script, that methodically scans or "crawls" through Internet pages to create an index of of the data it's looking for. Alternative names for a web crawler include web spider, web robot, bot, crawler,web scutter and automatic indexer. Other less frequently used names for web crawlers are ants, automatic indexers, and worms. The major search engines on the Web all have such a program, typically programmed to visit sites that have been submitted by their owners as new or updated.Entire sites or specific pages can be selectively visited and indexed. Crawlers apparently gained the name because they crawl through a site a page at a time, following the links to other pages on the site until all pages have been read. Using the information gathered from the crawler, a search engine will then determine what the site is about and index the information.

Crawling policies
The large volume of information available and the rate of change of it make crawling it very difficult.The large volume implies that the crawler can only download a fraction of the web pages within a given time, so it needs to prioritize its downloads.The high rate of change implies that by the time the crawler is downloading the last pages from a site, it is very likely that new pages have been added to the site, or that pages have already been updated or even deleted.The recent increase in the number of pages being generated by server-side scripting languages has also created difficulty in that endless combinations of HTTP GET parameters exist. Therefore, The whole process requires a focus of giving priority to Web pages. Function of a pages intrinsic quality, popularity of its URL and links are referred to as the importance of a page.

The behavior of a web crawler is the outcome of a combination of policies:

* A selection policy that states which pages to download.
* A re-visit policy that states when to check for changes to the pages.
* A politeness policy that states how to avoid overloading websites.
* A parallelization policy that states how to coordinate distributed web crawlers.

Selection policy
The importance of a page is a function of its intrinsic quality, its popularity in terms of links or visits, and even of its URL. Designing a good selection policy has an added difficulty: it must work with partial information, as the complete set of Web pages is not known during crawling.

Path ascending crawling:
Web Crawlers aim at accumulating as many resources as possible from a website. They accumulate information by downloading the information. In 2004, Cothey introduced a Path ascending crawler. This path crawler had the quality to ascend to every possible path in URL.

This crawler was considered extremely beneficial in tracing isolated resources. It even found out resources that would have not given own any inbound link in regular crawling.

Focused Crawling:
In a focused crawling, a function of the similarity of a page to a given query exhibits the significance of a web page for a crawler.

Deep web crawling:
There are many pages that cannot be accessed by regular crawlers if there are no links provided to them. These pages are found in the deep web and can be accessed only once the queries are submitted to a database.

Re-visit policy
The Web has a very dynamic nature, and crawling a fraction of the Web can take a really long time, usually measured in weeks or months. By the time a web crawler has finished its crawl, many events could have happened. These events can include creations, updates and deletions.
From the search engine's point of view, there is a cost associated with not detecting an event, and thus having an outdated copy of a resource. The most used cost functions are freshness and age.

Freshness: This is a binary measure that indicates whether the local copy is accurate or not.

Age: This is a measure that indicates how outdated the local copy is.

Web crawler architectures
A crawler must not only have a good crawling strategy, as noted in the previous sections, but it should also have a highly optimized architecture.A typical architecture is as shown.

Difficulties and limitation
The difficulties of web crawling include iaccessibility of certain portions of a website, portions of a web site that may be hidden in the Deep Web, web servers which return a different page for a web crawler than it would for a regular browser request, in order to fool search engines into sending more traffic to a website,Crawler traps etc. Not only must web archivists deal with the technical challenges of web archiving, they must also contend with intellectual property laws. National libraries in many countries do have a legal right to copy portions of the web under an extension of a legal deposit.

NFC - Short range connectivity!

2008-07-05T08:05:00.000-07:00

Near Field Communication or NFC, is a short-range high frequency wireless communication technology which enables the exchange of data between devices over about a 10 centimetre (around 4 inches) distance. The technology is a simple extension of the ISO 14443 proximity-card standard (contact less card, RFID) that combines the interface of a smartcard and a reader into a single device.

What is NFC?
Near Field Communication (NFC) is a short-range wireless connectivity technology standard designed for intuitive, simple and safe communication between electronic devices. NFC communication is enabled by bringing two NFC compatible devices within a few centimeters of one another. Applications of NFC technology include contactless transactions such as payment and transit ticketing, simple and fast data transfers including calendar synchronization or electronic business cards and access to online digital content.

A different world!
NFC makes life easier - it's easier to get information, easier to pay for goods and services, easier to use public transport, and easier to share data between devices. You simply bring NFC-compatible devices close to one another, typically less than four centimeters apart.Thanks to NFC technology, we will be able to "pick up" information from our environment. NFC technology allows mobile devices to "read" information stored in "tags" on everyday objects. These can be affixed to physical objects such as posters, bus stop signs, street signs, medicines, certificates, food packaging and much more. You will know where to find the tag by looking for the NFC Forum "Target Mark" on the object.

Specifications
Near Field Communication is based on inductive-coupling, where loosely coupled inductive circuits share power and data over a distance of a few centimeters. NFC devices share the basic technology with proximity (13.56MHz) RFID tags and contactless smartcards, but have a number of key new features. Like ISO 14443, NFC communicates via magnetic field induction, where two loop antennas are located within each other's near field, effectively forming an air-core transformer. It operates within the globally available and unlicensed radio frequency ISM band of 13.56 MHz, with a bandwidth of almost 2 MHz.
* Working distance with compact standard antennas: up to 20 cm
* Supported data rates: 106, 212, or 424 kbit/s
* In reader/writer mode, the NFC device is capable of reading NFC Forum mandated tag types, such as in the scenario of reading an NFC Smartposter tag. The reader/writer mode is on the RF interface compliant to the ISO 14443 and FeliCa schemes.
* In Peer-to-Peer mode, two NFC devices can exchange data. For example, you can share Bluetooth or WiFi link set up parameters, and exchange data such as virtual business cards or digital photos. Peer-to-Peer mode is standardized on the ISO/IEC 18092 standard.
* In Card Emulation mode, the NFC device itself acts as an NFC tag, appearing to an external reader much the same as a traditional contactless smart card. This enables contactless payments and e-ticketing, for example.

Coding and data rates
* NFC employs two different codings to transfer data. If an active device transfers data at 106 kbit/s, a modified Miller coding with 100% modulation is used. In all other cases Manchester coding is used with a modulation ratio of 10%.
* NFC devices are able to receive and transmit data at the same time. Thus, they can check the radio frequency field and detect a collision if the received signal does not match with the transmitted signal.
* NFC data transmission is measured in Kilo Bits Per Second (kbps). The NFC standard supports varying data rates, again to ensure interoperability between pre-existing infrastructure. The current data rates are 106kbps, 212kbps and 424kbps.

Advantages
Acting as a secure gateway to the connected world, tomorrow’s NFC-enabled mobile devices will allow consumers to store and access all kinds of personal data – at home or on the move. Simply by bringing two NFC-enabled devices close together, they automatically initiate network communications without requiring the user to configure the setup. NFC-enhanced consumer devices can easily exchange and store your personal data – messages, pictures, MP3 files, etc. Delivering ease of use, instant intuitive connectivity, zero configuration and smart key access, NFC meets all the needs of today’s connected consumer and creates opportunities for new mobile services.

RFID - the basics

2008-04-22T10:43:00.000-07:00

Radio-frequency identification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders.An RFID tag is an object that can be applied to or incorporated into a product, animal, or person for the purpose of identification using radiowaves. Some tags can be read from several meters away and beyond the line of sight of the reader.

RFID tags

RFID tags come in three general varieties:- passive, active, or semi-passive (also known as battery-assisted). Passive tags require no internal power source, thus being pure passive devices (they are only active when a reader is nearby to power them), whereas semi-passive and active tags require a power source, usually a small battery

Passive

Passive RFID tags have no internal power supply. The minute electrical current induced in the antenna by the incoming radio frequency signal provides just enough power for the CMOS integrated circuit in the tag to power up and transmit a response. Most passive tags signal by backscattering the carrier wave from the reader. This means that the antenna has to be designed both to collect power from the incoming signal and also to transmit the outbound backscatter signal. The response of a passive RFID tag is not necessarily just an ID number; the tag chip can contain non-volatile, possibly writable EEPROM for storing data.

Active

Unlike passive RFID tags, active RFID tags have their own internal power source, which is used to power the integrated circuits and to broadcast the response signal to the reader. Communications from active tags to readers is typically much more reliable (i.e. fewer errors) than from passive tags due to the ability for active tags to conduct a "session" with a reader.

Active tags, due to their on board power supply, also may transmit at higher power levels than passive tags, allowing them to be more robust in "RF challenged" environment with humidity and spray or with dampening targets (including humans/cattle, which contain mostly water), reflective targets from metal (shipping containers, vehicles), or at longer distances: Generating strong responses from weak reception is a sound approach to success. In turn, active tags are generally bigger, caused by battery volume, and more expensive to manufacture, caused by battery price. However, their potential shelf life is comparable, as self discharge of batteries competes with corrosion of aluminated printed circuits.

Semi-passive

Semi-passive tags, also called semi-active tags, are similar to active tags in that they have their own power source, but the battery only powers the microchip and does not power the broadcasting of a signal. The response is usually powered by means of backscattering the RF energy from the reader , where energy is reflected back to the reader as with passive tags. An additional application for the battery is to power data storage. If energy from the reader is collected and stored to emit a response in the future, the tag is operating active

Current uses

Passports : RFID tags are being used in passports issued by many countries.
Transportation payments: These are used for fare collection
Product tracking: High-frequency RFID tags are used in library book or bookstore tracking, jewelry tracking, pallet tracking, building access control, airline baggage tracking, and apparel and pharmaceutical items.
Animal identification: Implantable RFID tags or transponders can be used for animal identification.
Inventory systems: Auto-ID system based on the Radio Frequency Identification (RFID) technology has significant value for inventory systems.
Human implants : Implantable RFID chips designed for animal tagging are now being used in humans.

Future

Today, a significant thrust in RFID use is in enterprise supply chain management, improving the efficiency of inventory tracking and management. However, a threat is looming that the current growth and adoption in enterprise supply chain market will not be sustainable without linking the indoor tracking to the overall end-to-end supply chain visibility. Analysts such as Venture Development Corporation and wireless guru, Andrew Seybold believe that a single platform linking RFID to outdoor GPS tracking and cellular systems is required for a complete solution. This coupled with fair cost-sharing mechanisms, rational motives and justified returns from RFID technology investments are the key ingredients to achieve long-term and sustainable RFID technology adoption.

Mobile WiMAX Deployment Alternatives

2008-03-12T01:10:00.000-07:00

Traditionally, cellular deployments were based solely on achieving ubiquitous coverage with little consideration for capacity requirements. Since the only services offered were voice and the market was uncertain, this was a very reasonable approach. Moreover, the voice service offering is a low data rate application enabling traditional cellular networks to achieve wide outdoor and indoor coverage with a low data rate network (~10-15 kbps bandwidth depending on type of vocoder). As the customer base grew and more services offered, additional base stations were deployed and/or channels added to existing base stations to meet the growing capacity requirements. With Mobile WiMAX, however, operators will want to offer a wide range of broadband services with Quality-of-Service (QoS) support. To meet customer expectations for these types of services it will be necessary to predetermine capacity requirements and deploy accordingly at the outset. Careful deployment planning in anticipation of growing customer demands will ensure a quality user experience when the network is at its busiest.

Determining Capacity Requirements
Arriving at an accurate estimate of capacity requirements for new broadband services is not a simple exercise. One must anticipate how users will make use of the new services being offered and how often users will be actively engaged with the network. Data density, expressed as Mbps per km^2, is a convenient metric for describing capacity requirements. Determining the required data density for a specific demographic region is a multi-step process.The expected market penetration, or take-up rate, at maturity is dependent on a number of factors including the competitive situation and the services offered that distinguish one service provider from another. The service provider’s penetration may also vary within the metropolitan area since urban and dense urban residents will often have other broadband access alternatives from which to choose as compared to residents in suburban and rural areas.

Base Station Deployment Alternatives
Mobile WiMAX base station equipment will be available from many different vendors and, although all will be WiMAX compliant and meet performance and interoperability requirements, a great many different configurations will be available from which service providers can choose. The availability and timing of optional features also adds to the equipment variability. Additionally, there are different frequency bands that can be considered and varied amounts of spectrum availability within these bands. The spectrum choices will, in many cases, affect the frequency reuse factor and the channel bandwidths that can be employed in the access network.WiMAX solutions with beamforming will generally be architected quite differently from
SIMO and MIMO solutions. A typical SIMO or MIMO configuration will have power amplifiers mounted at the base of the tower to facilitate cooling and maintenance. The amplifiers in this case would have to be sized to compensate for cable losses, which can range from 2 to 4 dB depending on tower height and frequency. Beamforming solutions require good phase and amplitude control between transmitting elements and will often be architected with their power amplifiers integrated with the antenna elements in a tower-mounted array. The larger size and weight of these structures will also require more robust mounting. There is additional signal processing requirements for beamforming solutions with Adaptive Beamforming being the most computational intensive.

The selection of channel bandwidth and duplexing method can also have an economic impact on the varied WiMAX deployment alternatives. In addition the desired “worse case” UL rate will affect the UL link budget and therefore, impact the range and coverage of the base station.

Conventional cellular deployments used cell frequency reuse factors as high as seven (7) to mitigate intercellular co-channel interference (CCI). These deployments assured a minimal spatial separation of 5:1 between the interfering signal and the desired signal but required seven times as much spectrum. With technologies such as CDMA, introduced with 3G, and OFDMA, introduced with WiMAX, more aggressive reuse schemes can be employed to improve overall spectrum efficiency.

Number of Base Stations
The key metric for a quantified comparison will be the number of WiMAX base stations required to meet both capacity and coverage requirements in the varied demographic regions. The WiMAX base station is a key network element in connecting the core network to the enduser in that it determines the coverage of the network and defines the end-user experience. If too few base stations are deployed the coverage will not be ubiquitous and the end-user may experience drop outs or periods of poor performance due to weak signal levels as he moves throughout the coverage area. And since the base station investment will tend to be a dominant contributor to the total end-to-end network costs, deploying too many base stations can result in unnecessary start-up costs for the operator leading to a weaker business case.

Summing up
In the long term, the higher performance base stations with wideband channels provide a potentially more cost-effective deployment solution as measured by the number of required base stations. One might conclude that it would be worth waiting for antenna technologies such as beamforming and beamforming + MIMO and possibly even 20 MHz channels, before deploying a Mobile WiMAX network. This however, is not the case. In the early years , deployment can begin with range-limited base stations using (1x2) SIMO or (2x2) MIMO base station configurations to get ubiquitous coverage over the entire metropolitan area. These base stations can then be upgraded in the following years with beamforming and beamforming + MIMO as necessary to meet the capacity requirements in anticipation of a growing customer base. In most metropolitan area deployments this will only be necessary in the dense urban and urban areas.

Palpable computing : Is it the future?

2008-02-06T19:44:00.000-08:00

As computing technologies become an ever more ‘invisible’ and powerful part of our lives, it is crucial that people are supported in understanding what these technologies are doing and what they could do for them. The European research project PalCom develops the concept of ‘palpability’ for IT-design that fits the information age. By ‘palpable’ It is meant ‘noticeable’ and ‘understandable’. Palpability is not a property of technology itself, but an effect of people's engagement with technologies, objects, and environments.
Palpable computing is a new design initiative that envisions ubiquitous technologies that are designed to support people in making their actual and potential activities and affordances clearly available to their senses. Palpable systems support people in understanding what is going on at a level they choose and they support the user’s control and choice.

What is palpable computing ?
IT in everything from the kitchen toaster to the doctor’s stethoscope. Every day more and more devices and IT-systems enter our lives. ‘Palpable computing’ is a new concept for computing that will make technologies a lot easier to understand, use and construct on-the-fly. Palpable computing is essentially about doing pervasive computing right. It is about designing IT that is easy to grasp modify and understand for users.

Palpable computing moves beyond pervasive:
Pervasive computing acknowledges that the user benefits from technologies being small and invisible in use. The philosophy is to put the user in control by providing sufficient amounts of visibility. As a user you can have a device that is visible in the sense that it is aesthetically pleasing and fun to use. At the same time the user should be able to inspect breakdowns and errors on the particular device and be offered tools on how to find out what went wrong and how to correct the error.

How to explore palpability
The areas have been carefully selected and provide the researchers with a wide array of settings where palpability is a concern. All application areas are characterized by the use of a growing number of digital devices and a need for technologies that work better together and are easier to comprehend.

Application areas
While supporting an exceedingly heterogeneous and ever changing computationalenvironment, such as the accident scene, help users manage their tasks,whilst maintaining coherence and stability in the supporting systems without the need to focus on directly handling heterogeneity.

The system quietly supports human tasks; not be intrusive, obtrusive or interfere unless expected or told to doso.
Investigate and render visible the inner workings of the technology in order to understand what is going on.
Reconstruct newconfigurations from existing ones.
Handle errors and failures in a highly complex and heterogeneousmulti-user, multi-device, multi-service environment.

The Architecture

The Open Architecture is the technical nucleus. Its goal is to serveas the means of transcribing the challenges discussed in the previous section into a set of interrelated, computationally realised concepts drawn into a coherent, encompassingand meaningful architecture. This implies that it must capture the essence of how hu-man actors interact with, and within, their everyday environments through distributedpopulations of palpable and non-palpable entities. A PalCom System typically consists of services and assemblies running on multiplenetworked devices that together populate a user’s environment.The bottom layers represents the Hardware and the optional Operating System of devices participating in PalCom systems. These two layers are considered as pre-requisite and are therefore not subject to any special treatment with the architectural scope. The next layer, the Runtime Environment is the lowest aspect of the PalCom Ar-chitecture and is responsible for hosting PalCom Services on devices. With a PalComRuntime Environment in place a device can then be considered as being a PalCom-enabled device. The Common Infrastructure provides operational support for PalCom Services and Assemblies, including resource management, contingency managementand security. The architecture is in the process of being validated by a number of architecturalprototypes as work streams within the PalCom project.

Is it the future?

Virtually everyone stands to benefit from the more pervasive use of computer technology. But while adding microchips to more everyday objects can make lives easier – and even save them – the approach creates some unique problems of its own. “Palpable” rather than “ubiquitous” computing promises a solution.

DVD demystified

2007-12-27T22:15:00.000-08:00

DVD is a popular optical disc storage media format. Its main uses are video and data storage. Most DVDs are of the same dimensions as compact discs (CDs) but store more than 6 times as much data. Variations of the term DVD often describe the way data is stored on the discs: DVD-ROM has data which can only be read and not written, DVD-R and DVD+R can be written once and then functions as a DVD-ROM, and DVD-RAM, DVD-RW, or DVD+RW holds data that can be erased and thus re-written multiple times. But what really do all these stand for? Read on to know more...

History
"DVD" was originally used as an initialism for the unofficial term "digital video disc". It was reported in 1995, at the time of the specification finalization, that the letters officially stood for "digital versatile disc". Later the specification finalization only refers to the technology as "DVD", making no mention of what the letters meant! Usage in the present day varies, with "DVD", "Digital Video Disc", and "Digital Versatile Disc" being the most common.

In 1993, the MultiMedia Compact Disc, backed by Philips and Sony, and the Super Density disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC were developed. IBM's president, Lou Gerstner led an effort to unite the two camps behind a single standard, anticipating a repeat of the costly videotape format war between VHS and Betamax in the 1980s. Philips and Sony abandoned their MultiMedia Compact Disc and fully agreed upon Toshiba's SuperDensity Disc with only one modification, namely changing to EFMPlus modulation. EFMPlus was chosen as it has a great resilience against disc damage such as scratches and fingerprints. EFMPlus, created by Kees Immink, who also designed EFM, is 6% less efficient than the modulation technique originally used by Toshiba, which resulted in a capacity of 4.7 GB as opposed to the original 5 GB. The result was the DVD specification, finalized for the DVD movie player and DVD-ROM computer applications in December 1995. In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all other companies.

What writable DVD formats are available?
There are five kinds of writable DVD technology (DVD-R, DVD+R, DVD-RW, DVD+RW and DVD-RAM). Similar to CD-Recordable (CD-R), DVD-R and DVD+R discs are write-once incorporating a dye recording layer to which information is irreversibly written by means of a laser heating and altering it to create a pattern of marks mimicking the pits of a prerecorded (pressed/molded) DVD. DVD-RW and DVD+RW, on the other hand, closely resemble CD-ReWritable (CD-RW) by employing a phase-change recording layer that can be repeatedly changed and restored by the writing laser (approximately 1000 times). DVD-RAM also uses phase-change technology but can be rewritten roughly 100,000 times. With its hard sectors, random access capabilities and optional cartridge, DVD-RAM more closely resembles traditional disc-based storage media than do DVD-RW and DVD+RW. This separates DVD-RAM somewhat from the prerecorded DVD format that provides the basis for most DVD discs.

Technology
The DVD-ROM Drive typically uses 650 nm wavelength laser diode light as opposed to 780 nm for CD. This permits a smaller spot on the media surface (1.32 µm for DVD versus 2.11 µm for CD). Writing speeds for DVD were 1×, that is 1350 kB/s (1318 KiB/s), in the first drives and media models. More recent models at 18× or 20× have 18 or 20 times that speed. Note that for CD drives, 1× means 153.6 kB/s (150 KiB/s), 9 times slower.

DVD-R and DVD+R discs
Once written, single-layer (SL) DVD-R and DVD+R discs closely mimic the optical characteristics of single-layer (SL) prerecorded (pressed) DVDs. Thus, they can be read on the majority of computer DVD-ROM drives and DVD recorders. In addition, DVD-R and DVD+R discs are compatible with most consumer electronics (CE) DVD devices including portable, car and DVD players and recorders. Compatibility continues to evolve so newer devices are generally more able to play written discs. DVD+R It has slightly less storagecapacity than the DVD-R (only 4.3GB).

DVD-RW and DVD+RW discs
Written DVD-RW and DVD+RW discs can be read on the majority of computer DVD-ROM drives and DVD recorders as well as consumer electronics (CE) DVD devices including portable, car and DVD players and recorders. However, DVD-RW and DVD+RW discs have optical signal characteristics (lower reflectivity) closer to those of dual-layer (DL) prerecorded (pressed) DVDs which sometimes contributes to incompatibilities. The DVD+RW supports random write access, which means that data can be added and removed without erasing the whole disc and starting over (up to about 1000 times). With suitable support from the operating system, DVD+RW media can thus be treated like a large floppy disk, in contrast to DVD-RW which must be erased before re-writing can take place.

DVD Multi
The DVD Forum created the DVD Multi specification in 2001 to provide hardware manufacturers with the requirements necessary to make computer and consumer electronics (CE) DVD devices read or read and write most DVD disc formats sanctioned by the DVD Forum. Specifically, the DVD Multi specification requires that DVD Multi Players read DVD-ROM (prerecorded), DVD-R (General), DVD-RW and DVD-RAM discs and DVD Multi Recorders read and write those same formats. Be aware that DVD Multi does not prescribe that devices should accommodate DVD-RAM cartridges or 8 cm discs.

Configurations of writable DVD available
Currently, writable DVD discs are single-layer (SL) products which can either be single (SS) or double-sided (DS). Single-sided discs are used in everyday data and video applications while double-sided discs are more specialized (largely due to the lack of a convenient labeling surface) and are typically employed in automated storage jukeboxes and in writable DVD camcorders. In addition, DVD-RAM discs come as bare or can be enclosed in protective “cartridges”. Some types of these cartridges may be opened to allow the discs to be removed while others come permanently sealed. Be aware that not all DVD-RAM compatible drives, players and recorders accommodate cartridged discs.

Copying deterrents & Content Protection
To deter users from making disc-to-disc and other direct digital copies of commercial movies and audio albums, most prerecorded DVD-Video and DVD-Audio format discs are protected at the factory using (respectively) the Content Scrambling System (CSS) and Content Protection for Prerecorded Media (CPPM). CSS and CPPM selectively encrypt disc sectors that can only be decrypted during playback by licensed products (DVD players, computer DVD playback software and others). Critical information (decryption keys, album identifiers) required to unlock content is located in protected regions of these discs (Control Data Zone of Lead-in Area and sector headers) accessible to the player or drive and under only carefully regulated circumstances. Without these keys the encrypted video or audio is unusable. Performing bit-for-bit duplication or simply copying files from the disc to a writable DVD, hard drive or other storage medium will not yield a useful reproduction.
Nevertheless, over the years various computer software tools have emerged to allow the making of copies of CSS protected DVD-Video discs!

DVD-RW, DVD+RW and DVD-RAM rewritability
As is the case with other optical storage media using phase-change technology there is a limit to the number of times the recording layer in a DVD-RW, DVD+RW and DVD-RAM disc can be reliably switched between its crystalline and amorphous states. It is estimated that a DVD-RW or DVD+RW disc can be rewritten approximately 1000 times and a DVD-RAM 100,000 times. In addition, these formats (under certain circumstances) employ defect management schemes to actively verify data and skip over or relocate problems to a spare area of the disc.

Life span of Data on DVD
The life span of a written disc depends upon a number of factors including such things as the intrinsic properties of the materials used in the disc’s construction, the quality of its manufacture, how well it is recorded and the way it has been handled and stored. As a result, the life span of a recorded disc is extremely difficult to estimate reliably. To calculate disc life spans within some practical timeframe blank media manufacturers conduct accelerated age testing by subjecting samples of their discs to environments much beyond those experienced under normal storage conditions. Generally speaking, these tests only consider the effects of varying temperature and humidity. Results are then used to predict how long a disc will remain readable under more normal storage conditions. Questionable testing and measurement procedures can seriously impact upon and compromise these estimates so keep in mind that unlike prerecorded (pressed) CD and CD-R discs there are currently no international standards for conducting writable DVD accelerated testing. Writable DVDs and CDs may appear similar, but their construction and underlying design differ significantly so what applies to the one does not necessarily apply to the other.

See Also

http://www.osta.org/technology

Introduction to DVB technology

2007-10-29T22:41:00.000-07:00

DVB, short for Digital Video Broadcasting, is a suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project. The DVB Project is an industry-led consortium of over 260 broadcasters, manufacturers, network operators, software developers, regulatory bodies and others in over 35 countries committed to designing open interoperable standards for the global delivery of digital media services.DVB standards are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).

Background
Until late 1990, digital television broadcasting to the home was thought to be impractical and costly to implement. Towards the end of 1991, broadcasters, equipment manufacturers and regulatory bodies in Europe came together to form a group that would oversee the introduction of digital TV. A Memorandum of Understanding (MoU) was drawn up, setting out the basis on which competitors in the marketplace would come together in a spirit of trust and mutual respect. The MoU was signed in September 1993 by all ELG participants, and the DVB Project was born. A key report from the Working Group on Digital Television was also central to setting out important concepts that would go on to shape the introduction of digital TV in Europe and far beyond.

Market Deployment

By using technology based on the DVB standard it is expected to:

lower receiver costs
control which stations are entitled to receive program streams
encrypt the data
lower space segment costs through statistical multiplexing
reduce antenna sizes by using saturated transponders.

We can also expect to see specialized application software developed around the standard, supporting such features as QoS control, and scheduling. DVB systems distribute data using a variety of approaches, including by satellite (DVB-S, DVB-S2 and DVB-SH; also DVB-SMATV for distribution via SMATV); cable (DVB-C); terrestrial television (DVB-T) and terrestrial television for handhelds (DVB-H); and via microwave using DTT (DVB-MT), the MMDS (DVB-MC), and/or MVDS standards (DVB-MS). Open standards guarantee that compliant systems will be able to work together, independent of which manufacturer provided the equipment. Designed with a maximum amount of commonality and based on the MPEG-2 coding system, DVB signals may be effortlessly carried from one medium to another, a frequent need in today's complex signal distribution environment.

These standards define the physical layer and data link layer of the distribution system. Devices interact with the physical layer via a synchronous parallel interface (SPI), synchronous serial interface (SSI), or asynchronous serial interface (ASI). All data is transmitted in MPEG-2 transport streams with some additional constraints (DVB-MPEG). A standard for temporally compressed distribution to mobile devices (DVB-H) was published in November 2004. These systems differ mainly in the modulation schemes used, due to the different technical constraints. DVB-S (SHF) uses QPSK, 8PSK or 16-QAM. DVB-S2 uses QPSK, 8PSK, 16APSK or 32APSK, at the broadcasters decision. QPSK and 8PSK are the only versions regularly used. DVB-C (VHF/UHF) uses QAM: 16-QAM, 32-QAM, 64-QAM, 128-QAM or 256-QAM. Lastly, DVB-T (VHF/UHF) uses 16-QAM or 64-QAM (or QPSK) in combination with COFDM and hierarchical modulation.

Multimedia Broadcasting and Interactivity
Digital broadcasting has the capacity to deliver multimedia in addition to television programmes. This can look like an electronic version of a ‘magazine page’ or a web page. It is either independent of the television programme or allied to it in some way. It can be ‘one-way’ multimedia which displays pictures and information on screen - superimposed or separate - or it can be two-way multimedia which uses a return path system to the broadcaster, to allow the viewer to interact directly with the broadcaster. The information for the multimedia has to be delivered to the receiver in a way that can be predicted, and all the incoming information has to be coded in a language that is known to the receiver. The delivery of one way material is usually arranged in a ‘carousel’. This means that information is available in a repeating cycle. The receiver grabs the information the viewer has requested (via his controls) as it ‘goes by’. There can be a finite waiting time for broadcast multimedia whose length depends on luck and how much overall multimedia is being offered by the channel.

DVB Compliant Products
Companies that manufacture a product that is compliant to one or more DVB standards have the option of registering a Declaration of Conformity for that product. Wherever the DVB trademark is used in relation to a product – be it a broadcast, a service, an application or equipment – the product must be registered with the DVB Project Office. On July,2007, Nokia launched its new Nseries multimedia device, the N92, which the company claims is the world's first Digital Video Broadcast Handheld (DVB-H) enabled handset supporting Live Broadcast Mobile TV.Nokia's announcement follows the recent launch of DVB-H Mobile TV services in Delhi by national broadcaster, Doordarshan. Currently, DD's service comprises 8 popular free-to-air DD channels, including DD National, DD News, DD Sports, DD Bharati, DD Urdu, DD Punjabi, DD Bangla, and DD Podhigai, supported on DVB-H compliant handsets. A huge list of products can be found at http://www.dvb.org/

The Future
Media development is clearly moving toward greater convergence between different delivery systems, broadcast and point to point. Already agreed a number of IP and convergence orientated systems has been added. The future lies in the seamless interoperation of digital telephony systems and digital broadcasting and the emerging in-home network environments. The DVB should be able to help create an interoperable world for converged systems.

References
http://http://www.dvb.org/
http://en.wikipedia.org/
http://mhp.org/

An Introduction to SystemC

2007-09-18T00:52:00.000-07:00

Introduction

Typically, today’s complex embedded systems comprise application-specific hardware and software to meet the stringent requirements. Modern embedded systems developed on a tight schedule, the systems have tight real-time performance constraints, and thorough functional verification is required to avoid catastrophic failures. SystemC is a language that has evolved in response to a pervasive need for a language that improves overall productivity for designers of all types of electronic systems. SystemC offers real productivity gains by letting engineers design both the hardware and software components together as these components would exist on the final system, at a high level of abstraction. This higher level of abstraction essentially improves the productivity gains.

The language

SystemC cannot be called a language, it is rather a class library within a well established language, C++. SystemC is not expected to solve every design productivity issue. SystemC, coupled with the SystemC Verification Library provides many of the characteristics relevant to system design and modeling tasks that are missing or scattered among the other languages. Additionally, SystemC provides a common language for software and hardware, C++. Although Ada and Java have proven their value, C/C++ is predominately used today for embedded system software.

SystemC addresses the modeling of both software and hardware using C++. We all know C++ already addresses most software concerns. SystemC, in addition, provides mechanisms that are useful in modeling the hardware while using a language environment which is compatible with software development. It also provides several hardware-oriented constructs that are not normally available in a software language but are required to model hardware. All of the constructs are implemented within the context of the C++ language. The relative comparison of systemC with other hardware languages is given in figure.

System Design

The latest OSCI reference SystemC release is available for free from http://www.systemc.org/. The download contains scripts and make files for installation of the SystemC library as well as source code, examples, and documentation. Design methods surrounding SystemC are currently maturing and vary widely. Although tools and language constructs exist in SystemC to support register-transfer-level (RTL) modeling and synthesis, language supports higher abstraction levels than RTL. In the next few years, the distributed methods are expected to settle into a cohesive design methodology.

Enhancing Productivity

Unless a new language solves a problem that current languages do not address, there is no practical reason for the evolution of that language. The primary boosting factor for using SystemC is the productivity increases required to design modern electronic systems with their ever increasing complexity. SystemC supports several approaches currently used for attacking the complexity issues that come with complex system design. Some of them are

Abstraction

Design reuse

Team discipline

Project reuse

Automation

SystemC makes design easy by employing all the five techniques effectively. That is why SystemC is emerging as today’s design language standard.

For more information on SystemC

http://www.systemc.org/

http://www.testbuilder.net/

http://www.ti.informatik.uni-tuebingen.de/~systemC/

http://www.nascug.org/

SYSTEMC: FROM THE GROUND UP By David C. Black and Jack Donovan, KLUWER ACADEMIC PUBLISHERS

WiMAX MIMO Antennas

2007-08-15T21:17:00.000-07:00

Introduction
Wireless operators are increasingly pressured to enhance their networks and service capabilities in order to keep pace with the accelerating growth in wireless utilization and increasing demand for high performing connections. As bandwidth intensive, rich media applications are introduced, larger volumes of subscribers consume ever-growing quantities of data packets while continuing to utilize more minutes of voice. Simply acquiring more spectrum channels and deploying more sites to resolve capacity issues can be decidedly inefficient and costly.

Revolutionary multiple antenna techniques at the base station and end-user device, paired with sophisticated signal processing, can dramatically improve the communications link for the most demanding application scenarios including heavily obstructed propagation environments and high speed mobility service. Where conventional wireless network design has long used base site sectorization and single, omni-directional antennas at the end-user device to serve the communications link, with advanced multi-antenna implementations operators have a new suite of tools to develop the robust wireless networks of the future.

Mobile WiMAX has offered the industry a very capable platform by which to deliver the demanding service requirements for wireless access today and tomorrow. With the added support for a variety of advanced multi-antenna implementations, Mobile WiMAX offers the wireless operator considerable relief in meeting their growing network demands with higher performance, fewer sites, less spectrum, and reduced cost.

The Challenges of Multipath
One of the greatest challenges to traditional wireless systems has been managing multi-path fading environments. Multi-path fading is the resulting signal degradation due to obstructions between a wireless transmitter and its intended destination. In a Non Line of Sight (NLOS) environment, a transmitted signal may bounce off of a myriad of obstacles including buildings, roads, and man-made structures as well as trees, hills, and naturally occurring impediments. With each bounce, a separate instance of the signal makes its way to the destination receiver with a variation in time. These multiple, "bounced" signals may interfere with one another resulting in a degraded signal at the receiver.

Perhaps somewhat counter-intuitive, where multipath and challenging propagation environments were once considered an adversary to wireless systems, with multi-antenna implementations, the wireless system actually benefits from the multipath phenomenon – leveraging multipath to create a more robust communications channel.

Multiple Antenna Technologies

Industry vendors and sources have created a host of naming conventions to refer to multi-antenna implementations. Simply put, the term MIMO (multiple input multiple output) can be used to reference any multi-antenna technologies.

Textbook MIMO configurations are represented as either "Open Loop" or "Closed Loop". In application, the commonly used MIMO terminology has most often been in reference to Open Loop MIMO techniques. The WiMAX standard includes two versions of Open Loop MIMO techniques referred to as Matrix A and Matrix B.

Closed Loop MIMO techniques, also known as Transmitter Adaptive Antenna (TX-AA) techniques, are simply referred to by the industry as "beamforming".
WiMAX infrastructure portfolios delivered today from leading industry vendors consider approaches to MIMO Matrix A, MIMO Matrix B and beamforming as a means to capitalize on the tremendous performance capabilities of these techniques.
MIMO Matrix A & MIMO Matrix B
Open Loop MIMO
With Open Loop MIMO, the communications channel does not utilize explicit information regarding the propagation channel. Common Open Loop MIMO techniques include Space Time Block Coding (STBC) and Spatial Multiplexing (SM-MIMO), and Collaborative Uplink MIMO. In WiMAX systems MIMO Matrix A refers to the STBC technique and MIMO Matrix B refers to the SM-MIMO technique.
Beamforming
Closed Loop MIMO
With Closed Loop MIMO, the transmitter collects information regarding the channel to optimize communications to the intended receiver. Closed Loop MIMO typically utilizes Maximum Ratio Transmission (MRT) or Statistical Eigen Beamforming (EBF) techniques leading to the shorthand name for this approach – beamforming.

MIMO Matrix A & Matrix B
MIMO Matrix A (STBC) and MIMO Matrix B (SM-MIMO) leverages multi-antenna operations at the base station and the end-user device. Matrix A and Matrix B with two antenna receivers is a required Wave 2 WiMAX Forum certification feature for WiMAX devices and will be a supported capability in the broad pool of certified equipment.
Enhancing Coverage
MIMO Matrix A (STBC)
With MIMO Matrix A, a single data stream is replicated and transmitted over multiple antennas. The redundant data streams are each encoded using a mathematical algorithm known as Space Time Block Codes. With such coding, each transmitted signal is orthogonal to the rest reducing self-interference and improving the capability of the receiver to distinguish between the multiple signals. With the multiple transmissions of the coded data stream, there is increased opportunity for the receiver to identify a strong signal that is less adversely affected by the physical path. The receiver additionally can use Maximal-Ratio Combining (MRC) techniques to combine the multiple signals for more robust reception. MIMO Matrix A is fundamentally used to enhance system coverage.
Increasing Capacity
MIMO Matrix B (SM-MIMO)
With MIMO Matrix B, the signal to be transmitted is split into multiple data streams and each data stream is transmitted from a different base station transmit antenna operating in the same time-frequency resource allocated for the receiver. In the presence of a multipath environment, the multiple signals will arrive at the receiver antenna array with sufficiently different spatial signatures allowing the receiver to readily discern the multiple data streams. Spatial multiplexing provides a very capable means for increasing the channel capacity.
The Best of Both Techniques
Adaptive Mode Selection
In those environments where the Signal to Noise Ratio (SNR) is low, such as the edge of the cell or where the signal is weak, MIMO Matrix A outperforms MIMO Matrix B. At higher SNR, where the system is more prone to be bandwidth limited rather than signal strength limited, MIMO Matrix B outperforms MIMO Matrix A. An ideal WiMAX system employing MIMO techniques will support both Matrix A and Matrix B. The system will calculate an optimal switching point and dynamically shift between the two approaches to offer the necessary coverage or capacity gains demanded from the network at any given time or location.
Collaborative Uplink MIMO
Collaborative Uplink MIMO is an additional open-loop MIMO technique considered by WiMAX vendors to increase the spectral efficiency and capacity of the uplink communications path. A practical realization of this technique would allow for two separate end-user WiMAX devices, each having a single transmit lineup, to utilize the same frequency allocation to communicate with the dual-antenna WiMAX base station. This technique can effectively double the uplink capacity of the WiMAX system

Beamforming
WiMAX systems that use beamforming as a means to further increase system coverage and capacity can surpass the capabilities of MIMO techniques. Beamforming techniques such as Statistical Eigen Beamforming (EBF) and Maximum Ratio Transmission (MRT) are optional features in the 802.16e WiMAX standard, but leading vendors are taking advantage of its strong performance characteristics.

Beamforming techniques leverage arrays of transmit and receive antennas to control the directionality and shape of the radiation pattern. The antenna elements have spatial separation dictated by the wavelength of transmission and are supported by sophisticated signal processing. See the attached picture

Channel information is communicated from the WiMAX subscriber to the WiMAX base station using the "uplink sounding response" – a mandated device feature for WiMAX certification. Based on the understanding of the channel characteristics, the WiMAX base station utilizes signal processing techniques to calculate weights to be assigned to each transmitter controlling the phase and relative amplitude of the signals. By leveraging constructive and destructive interference, the radiation pattern is steered and formed to provide an optimal radiation pattern focused in the direction of communication.

When transmitting a signal, beamforming can increase the power in the direction the signal is to be sent. When receiving a signal, beamforming can increase the receiver sensitivity in the direction of the wanted signals and decrease the sensitivity in the direction of interference and noise. While the processing requirements for beamforming can be quite sophisticated and resource intensive depending on the complexity of the channel and the number of subscribers on the system, today’s implementations can resolve the beam weights within 5 to 10 ms allowing for practical WiMAX solutions.

Beamforming techniques allow the WiMAX system to realize increased range with higher antenna gain in the desired direction of communications and better connectivity between the base station and device. Simultaneously, the narrower beamwidth and reduced interference increases the capacity and throughput offered by the system.

While both MRT and EBF are similar techniques in principal, the algorithms supporting each offer advantages in varying application scenarios. For MRT to deliver strong system gains, the technique requires a more exact measurement and understanding of the channel conditions. As such, MRT is a more opportune technique when communicating with static receivers. For mobile receivers, the delay between measuring the channel condition and forming the beam becomes a significant factor for delivering the necessary system gains. In these mobile
environments, EBF offers a more robust technique. Ideally, WiMAX beamforming solutions would adopt both MRT and EBF techniques to provide a more holistic beamforming solution that capably addresses both fixed and mobile applications.

WiMAX Device Requirements

Multi-antenna implementations in WiMAX systems are most efficient when the WiMAX subscriber also has multiple antennas and the necessary receiver capabilities. While techniques such as MIMO Matrix A and beamforming can demonstrate some improvements in the communications link, even with a single antenna subscriber, multi-antenna implementation will deliver the full advantages of the advanced antenna techniques.

On the other hand, MIMO Matrix B implementation requires parity in the number of antennas at the base station and the subscriber. The full benefit of MIMO Matrix B is limited to the lesser of the number of transmit and receive chains at the base station or device.

Two receive antenna systems are mandated for WiMAX Wave 2 device certification and this capability is likely to be most readily supported by chipset and device manufacturers. As such, two transmit and two receive MIMO implementation at the base station provides an efficient means for designing a WiMAX system.

When a WiMAX subscriber registers onto a WiMAX network, the subscriber informs the WiMAX base station what its capabilities are. This information may include support for MIMO Matrix A, MIMO Matrix B, or beamforming. Based on this information, the WiMAX base station will recognize how to best communicate with that WiMAX subscriber to optimally manage the communications link.

Flexible Deployment Scenarios

WiMAX is a versatile technology with relevance to a wide variety of application scenarios spanning from fixed, nomadic, mobile, indoor and outdoor communications. When designing a WiMAX system, factors including capacity or coverage requirements, fixed or mobile application, sectorization and reuse schemes will all contribute to determining the right feature set and capability requirements at the WiMAX base station.

MIMO Matrix B becomes an attractive option in urban environments where there is a rich multipath condition. Additionally, indoor communications where signals are likely to bounce off the walls, ceiling, and floor also provides a good environment for Matrix B. With a two antenna implementation, MIMO Matrix B can double the throughput over a single antenna implementation.

MIMO Matrix A is a good choice for suburban and rural geographies where there is less likelihood for strong multipath and the signal to noise ratio might be weaker. Additionally, MIMO Matrix A can be an effective choice for higher speed mobility applications where, again, the signal to noise ratio might be reduced. In these scenarios MIMO Matrix A with a two antenna implementation can double the system link budget over a single antenna implementation substantially boosting the coverage area.

While Matrix A is primarily used to realize coverage gains and Matrix B is used to offer capacity increase, an ideal system will dynamically switch between Matrix A and Matrix B depending on the specific application, geography, or link condition.

For those environments where further gains in coverage or capacity are required beyond what can be delivered by Matrix A and Matrix B implementations, beamforming solutions should be considered. With a four antenna implementation, the WiMAX system can realize up to a 12 to 16dB gain in link budget over a single antenna system – that amounts to well over a sixteen-fold improvement.

Of course, the throughput and coverage capabilities of WiMAX systems are highly influenced by the radio environment, the profile of data and voice traffic on the network, frequency planning, and subscriber loading. Careful profiling of the service requirements for the WiMAX network combined with sophisticated RF modeling using detailed topological information of the service geography are a critical component for planning a deployment approach. Experienced analysis can provide the necessary insights as to the optimal combination of RF solutions and multi-antenna techniques on a site-per-site basis - ultimately resulting in an optimized business model.

Conclusion

An optimized WiMAX system design must address the operator’s market-specific requirements including frequency planning, deployment geography and planned service offerings. Additionally, these requirements may vary throughout an operator’s service perimeter and may evolve over time.

Operators can design the best-fit network – mixing and matching across a host of base station types - when they have access to a range of infrastructure options with varying capabilities that address diverse deployment scenarios and operate under common management and controls.
WiMAX operators can select the right base station to serve a particular site requirement and configure it to support a wide assortment of coverage, capacity, and application scenarios. With a broad portfolio of infrastructure choices including macro/micro, outdoor/indoor, sectorized/omni, tower-top electronics/distributed electronics, MIMO and beamforming techniques, WiMAX operators can rapidly deploy an optimized network tuned to the varying requirements in their service footprint today and easily grow and scale to meet the growing demands of tomorrow.

The future of CMOS, High -k materials

2007-08-01T01:17:00.000-07:00

From the cellular phone to the personal digital assistant, miniaturization is omnipresent in our everyday life. In electronics, this trend is translated into Moore's law, which is often state as the doubling of transistor performance and quadrupling of the number of devices every three years. The fundamental building blocks for all computer chips—transistors—have tracked with Moore's Law for forty years. But as transistors shrink, leakage current can increase. Managing that leakage is crucial for reliable high-speed operation, and is becoming an increasingly important factor in chip design. Most everyone has heard that silicon is the material primarily responsible for the miraculous surge in computing power that is reshaping society. That's true, but silicon couldn't have done it alone. The well-known semiconductor's oxide, which chip makers grow or deposit on exposed silicon surfaces, has also played a crucial role.

Component density
The density of components on microcircuits has grown exponentially since the early days of the industry, doubling roughly every 18 months. It's a grueling rate of change that the industry has come to expect. For anyone who can't keep up, "the penalty is death" . To achieve greater component density, circuit makers use optical methods, such as lenses, to shrink the patterns (used for making the chipps)-a strategy called scaling. They must then make other adjustments, such as altering the recipes and thicknesses of deposited materials, in order for the diminished devices to work properly. From the start, silicon dioxide has been one of the stars of this scaling process. However, circuits have become so small that the material can no longer keep up. Silicon dioxide is losing its attractiveness in different microcircuit applications for opposite reasons. In its role in the transistors of integrated circuits, it no longer promotes accumulation of electric charge strongly enough. In engineering language, it has too low a value of a property called the dielectric constant, or k. To build next-generation transistors, scientists are working with new materials that show promise for replacing the silicon dioxide gate dielectric—where continued thinning makes it increasingly difficult to control current leakage. This thicker class of materials, known as "high-k," will replace today's silicon dioxide technology and then provide extendability over several generations.However, replacing the SiO2 with a material having a different dielectric constant is not as simple as it may seem. The material bulk and interface properties must be comparable to those of silicone dioxide, which are remarkably good.

High-k materials
"High-k" stands for high dielectric constant, a measure of how much charge a material can hold. Different materials similarly have different abilities to hold charge. Imagine a sponge, which can hold a great deal of water; wood, which can hold less; and glass, which can hold none at all. Air is the reference point for this constant and has a "k" of one. "High-k" materials, such as hafnium dioxide (HfO2), zirconium dioxide (ZrO2) and titanium dioxide (TiO2) inherently have a dielectric constant or "k" above 3.9, the "k" of silicon dioxide.The higher "k" increases the transistor capacitance so that the transistor can switch properly between and "ON" and "OFF" states, with very low current when off yet very high current when "ON". After years of research, Intel is said to have identified the right high-k material and the right type of gate electrode materials to achieve record performance for both NMOS and PMOS technologies. By moving to a new high-k material, Intel was able to keep the drive current at the same level as with older materials—and overcome the leakage. Intel anticipates that this shift to a new material will be one of the most significant in the evolution of the metal-oxide silicon (MOS) transistor, which has had a silicon dioxide dielectric gate since its introduction in the 1960s. Intel's new high-k material will also require a new manufacturing process to lay down a thickness of one molecular level at a time.

The path to High-k
Limitations drive the migration to high-k dielectrics. The focus is mainly on HfO2 or ZrO2, with emphasis on HfO2 or hafnium silicate. Some alumina and lanthanum composites also display these properties. These materials are ceramic-like and difficult to deposit because their precursors — chlorine, hydrogen or carbon — can be contaminants. Even if successfully deposited, electrical properties must be considered. High mobility is necessary to avoid transistor channel problems. More now than ever, OEMs and users are sharing what they do and how they are doing it, and are closely working together. The need to know more about differences in these materials, and the types of structures that are going down and how they are going down is on the anvil. A whole new level of cooperation will be needed to migrate to the next level!.

OFDM.. enabling New generation communication standards

2007-06-28T08:22:00.000-07:00

The principles of orthogonal frequency division multiplexing (OFDM) modulation have been in
existence for several decades. However,its only recently that the techniques have moved out of
text books and researchers benches to modern communications systems. OFDM is conceptually
simple, but the devil is in the details! The implementation relies on very high speed digital signal processing and this has only in the last several years become available at a price that makes OFDM a competitive technology. The advantage of OFDM claims to have is its ability to cope with severe channel conditions. OFDM is sometimes called multi-carrier or discrete multi-tone modulation.

What is OFDM?

The Conventional single-carrier modulation system uses modulation of information onto one
single carrier, utilizing frequency, phase, or amplitude adjustments of carrier. Frequency
division multiplexing (FDM) extends this very concept by using multiple subcarriers within the same single channel. The total data is divided between the various subcarriers. FDM systems require a guardband between its subcarriers to prevent these frim interfering with each other. These guardbands effectively lower the system’s information rate. If the FDM systems use a set of subcarriers that were "orthogonal" to each other, a higher level of spectral efficiency can be achieved. The use of orthogonal subcarriers would allow the subcarriers’ spectra to overlap, thus increasing the spectral efficiency. As long as orthogonality is maintained,it is possible to recover the individual subcarriers’ signals eventhough the spectra are overlapped.

Orthogonality holds the Key...

The main concept of OFDM lies in the orthogonality of the carriers. To be orthogonal, the dot product of two signal must result in zero. It is common to use the following inner product for two functions f and g

{f, g } = int[ f(x)g(x)] dx.

The functions 1, sin(nx), cos(nx) : n = 1, 2, 3, ... are orthogonal with respect to Lebesgue measure on the interval from 0 to 2π. This fact is basic in the theory of Fourier series. The communication system can be viewed from a stochastic processes' perspective. If two random processes are uncorrelated, then they are orthogonal. This view of orthogonality gives a simpler understanding of the implications of orthogonality in OFDM. Relating it to the Fourier series, which is nothing but a representation of signals as a combination of mutually orthogonal signals,is really intutive. In fact,OFDM implementation is done using DFT techniques.

Imlpementation

The DFT and IDFT form a transform pair widely used to convert signals from time to frequency domain and back. carriers. For example, the IDFT is used to convert frequency-domain data to time-domain data. For this,the IDFT correlates its inputs with its orthogonal basis functions which are sinusoids at certain frequencies. This is equivalent to mapping the input data on to the sinusoidal basis functions. It is easier said than done! In practice, OFDM systems implement a combination of Fast Fourier Transform(FFT) and inverse Fast Fourier Transform(IFFT) blocks that are mathematically equivalent;but more efficient ways to implement DFT and IDFT.

Channel performance

For the purpose to eliminate the effect of ISI, the guard interval could consist of no signals at all. Guard interval (or cyclic extension) is used in OFDM systems to combat against multipath fading. In that case, however, the problem of intercarrier interference (ICI) would arise. The reason is that there is no integer number of cycles difference between subcarriers within the interval.To eliminate ICI, the OFDM symbol is cyclically extended in the guard interval. This ensures that delayed replicas of the OFDM symbol always have an integer number of cycles within the interval, as long as the delay is smaller than the guard interval.

OFDM Challenges

Experts agree that there are, practical difficulties to achieve real time synchronization for OFDM frames. The technique is extremely sensitive to the frequency offsets. Also, spectral nulls in the useful transmission band will conduce to severe performance degradation on the affected sub-carriers. OFDM symbols have a high peak-to-average power ratio (PAPR) that makes them unsuitable for RF amplifiers Finally, but not last, full capabilities of OFDM can be achieved only if the channel impulse response is known, assumption that is not always met; complex channel estimation techniques must be used in order to achieve this need. Present studies in OFDM range focus on these drawbacks and in the finding of the means to overcome them.