The Telecom blog

IMT Advanced (4G) status for LTE

2010-11-08T20:02:00.002+05:30

The 3GPP c andidate technology submission for IMT-Advanced developed as LTE Release 10 (LTE-Advanced) has been accepted as a 4G technology at the Chongqing meeting of ITU-R. The IMT-Advanced process complies with or exceeds the ITU established criteria in all aspects. This reinforces the global preeminence of the work of 3GPP which unites the leading mobile technology companies in developing market oriented high performance broadband mobile wireless systems. Final ratification of the full IMT-Advanced technology family will occur by November 2010. 3GPP in conjunction with its Organizational Partners, will provide the detailed technical specifications and standards to the ITU-R by 2011, for inclusion in the Recommendation ITU-R.

IMT-Advanced supports the evolving and expanding needs of the broad international base of mobile operators and allows the users of wireless mobile broadband to experience, on a global basis, a rich and innovative range of service and capabilities that is unparalleled by any other technology.

Ref : 3gpp.com

Mobile TV

2010-07-24T08:33:00.003+05:30

It has been quite some time that we have seen some form of mobile TV or other. The technology has been existing for a while but has not matured yet. It is yet to find its foothold in many countries around the world. Mobile TV is expected to combine broadcast content with streamed and downloaded contents.

Mobile TV
Mobile TV means television contents that can be watched on small hand-held devices. It may be a pay TV service broadcast on mobile phone networks or received free-to-air via terrestrial television stations from either regular broadcast or a special mobile TV transmission format. Some mobile televisions can also download television shows from the internet, including recorded TV programs and podcasts.i.e. the content may be obtained either through an existing cellular network or a propriety network.

Standards
DVB-H (Digital Video Broadcasting - Handheld)
This is the major one of the mobile TV formats. DVB-H was formally adopted as ETSI standard as early as in November 2004. DVB-SH (Satellite to Handhelds), DVB-NGH (Next Generation Handheld) are possible enhancements to DVB-H, providing improved spectral efficiency and better modulation flexibility.

ATSC-M/H (Advanced Television Systems Committee - Mobile/Handheld)
This standard for mobile digital TV allows TV broadcasts to be received by mobile devices. ATSC-M/H is an extension to the available digital TV broadcasting standard ATSC A/53. ATSC is optimized for a fixed reception and uses 8VSB modulation.

MediaFLO
This technology transmits video and data to portable devices. In the United States, the service powered by this technology is branded as FLO TV. Broadcast data transmitted via MediaFLO includes live, real time audio and video streams, as well as scheduled video and audio clips and shows. The technology can also carry Internet Protocol data-cast application data.

WiMax 2

2010-05-11T09:39:00.004+05:30

It has not been long since we saw the first WiMax implementation. And even as we are getting a feel of it Wimax 2 has been announced. A consortium WCI has been announced which will strive for meeting the standards set by WiMax 2. The WCI (WiMAX 2 Collaboration Initiative ) is an initiative lead by leading WiMAX™ silicon suppliers, equipment makers and research organizations to accelerate interoperability of WiMAX 2 based on the IEEE 802.16m standard.

What is WiMax 2?
WiMAX 2 is the next phase of WiMAX technology which is based on the IEEE 802.16m standard. This standard has been built upon the existing 802.16e standard by adding new capabilities while maintaining backward compatibility. Yes, WiMax 2 will be backward compatible to the existing WiMax standard. WiMAX 2 offers higher system capacity with peak rates of more than 300 Mbps, lower latency and increased VoIP capacity, meeting the International Telecommunications Union (ITU) requirements for 4G technology.WiMAX forum vice president Mohammad Shakouri says the goal is for the new WiMAX standard to deliver average downlink speeds of more than 100Mbps to users. 802.16m amendment will provide the basis for WiMAX System Release 2 and provide existing WiMAX operators a graceful migration path to gain performance enhancements and add new services. IEEE 802.16m specification is expected to be completed by end of the in the 3rd quarter of 2010.

Improvements
WiMax 2 is expected to offer improved performance in areas like
• Coverage and Spectral Efficiency
• Power Conservation
• Data Capacity and VoIP capabilities
• Lower Latency and QoS Enhancements
• Inter-working with other Wireless Networks
• Multi-carrier support
• GPS based services
• Self-Organizing network features

Future of WiMAX
According to WiMAX forum, nearly 45 companies have actively supported IEEE 802.16m as an IMT-Advanced technology alternative. It is widely expected that both LTE-Advanced and 802.16m will be included. The performance enhancements defined in IEEE 802.16m build on the capabilities established with IEEE 802.16e-2005, which has 4 years of worldwide, field-proven experience. This assures backwards compatibility, hence WiMAX System Release 2 will provide a graceful migration path for today’s WiMAX operators. This also provides them the confidence that they have selected a proven technology that is structured to meet current and future network demands. With this evolutionary growth path, the WiMAX technology is well-positioned to
meet the challenges and demands anticipated for the next generation of mobile networks.

Ref: www.wimaxforum.org

Femtocell : Devices on offer and Companies

2010-04-29T16:13:00.001+05:30

Texas Instruments Incorporated had recently announced a new family of DSPs (TCI series) with a view of enabling the upcoming femtocell compliant device manufacturers as well as the service providers to cut the development time and bring their products to market faster. TI has announced a full set of analog solutions as well. Software reference designs are available which provide customers with all references required for Layer 1, 2 and 3 wireless protocol processing.

picoChip was one of the the first companies in the world to offer a femtocell modem. picoChip claims to have the industry's broadest portfolio of femtocell solutions. They have a family of Socs (PC3xx) all aimed at femtocell configurations in one form or other.

Percello is another company that offers integrated, low-cost digital baseband processors for WCDMA and LTE Femtocells. Percello provides many customized solutions that reduce the design challenges of Femtocell equipment vendors in the market.

DesignArt’s DAN2xxx series of SoCs provide a platform specifically targeted at WiMAX femtocell and repeater designs. These are optimized for low-cost, high performance indoor access point applications. The key features include high level of functional integration, complete PHY and MAC baseband solution, control plane, networking and home gateway application processing.

Analog Devices offers a 3G integrated Radio transceiver aimed at offering high-performance 3G femtocell solutions. Another offering is a from the MxFE family of integrated converters for the communications market. Analog devices claim that the device is ideally suited for low-cost, high-performance femtocell applications.AD also has a range of devices including accurate clock references, RF amplifiers and an evaluation board too.

There are several other companies like Qualcomm Inc. and Runcom Technologies Ltd who are working on the dvelopment of a femto-chip.

HSPA, HSDPA, HSUPA: confused?

2010-04-28T11:04:00.002+05:30

How often have we been into this situation? We step into a mobile phone store and you are bombarded with features and tech jargon. The moment we decide to step into 3G enabled world these terms are thrown at us.. HSPA, HSDPA, HSUPA.. What do they really mean and how are they really related?

Evolution of Mobile Broadband
One of the most important features of a 3G mobile service is the high speed data access. As the market expands, requirement also increases, thereby bringing in the necessity for new standards. Most of the data access traffic is downlink oriented or just like in an internet access biased towards the end user. Improving this will result in a better user experience.

HSDPA, HSUPA, HSPA
HSDPA (High-Speed Downlink Packet Access) is a 3G mobile communications protocol in which the networks can offer higher data transfer speeds and capacity. Currently HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.0 Mbit/s. Its true that most of the traffic is downlink oriented, still,there are a few applications that will benefit from an improved uplink. Typical examples are large pictures, movies etc. The 3G service which provides an enhanced uplink is the HSUPA (High-Speed Uplink Packet Access). So whats HSPA then? HSDPA and Enhanced Uplink are together known as High Speed Packet Access (HSPA)! Another term you might encounter in the near future is HSPA+ (also called Evolved HSPA). This is an upcoming wireless broadband standard which is expected to provide data rates up to 42 Mbps in the downlink and 11 Mbps in the uplink. A post on HSPA+ is already there in this blog.

So be armed with the knowledge next time you step into a phone store!!!!

3GPP release 10: What to expect

2010-04-22T10:54:00.001+05:30

Releases 8 and 9 of 3GPP covered the functionalities required to support the Home Node B (HNB) and Home eNodeB (HeNB). The new release aims to take these further and adds functionalities that will enable the mobile operators to provide services in a more effective manner, improving overall user experience. Several existing requirements on TS 22.220 which could not be realized in the previous stages are re-introduced. These are expected to be covered with Rel-10. This includes "Managed Remote Access to home based network", and "IMS Inter-working". It also features work on the studies related to machine-to-machine communications which enable network operators to offer machine-type communication services at a low cost level, to match the expectations of mass-market machine-type services and applications.Rel-10 aims to provide mechanisms enabling operator's control on routing of active PDN connections across available accesses. Another important feature is a solution to enable the operators seamlessly offload their traffic via IP flow mobility on to a WLAN. Operators will be able to use WLAN as a seamless extension of their cellular access and thus increase the overall system capacity while minimizing the access cost. On the RAN front, amendment of the 1.28Mcps TDD Home NodeB related specifications is proposed so as to support the Home NodeBs application.

The detailed overview of the specification is available from 3GPP.

3GPP Picks Femtocell Standards

2010-04-21T14:02:00.002+05:30

The 3rd Generation Partnership Project (3GPP) standards body has finally adopted an official architecture and started work on a new standard for home base stations. The specification for the interface between the Home Node B (HNB, the 3GPP term for femtocell) is being decided. The new interface will be called Iu-h and is a blend of existing standards Iu and generic access network (GAN), sometimes referred to as unlicensed mobile access (UMA). The 3GPP chose the solution backed by industry majors Alcatel-Lucent , Kineto Wireless Inc. , and its partners Motorola and NEC Corp. The new standard, which forms part of 3GPP’s Release 8, and interdependent with Broadband Forum extensions to its Technical Report-069 (TR-069), has been completed in just 12 months following close cooperation between 3GPP, the Femto Forum and the Broadband Forum.

Femtocells
The term has already been introduced to in one of the earlier posts. Femtocells are low-power wireless access points that operate in licensed spectrum to connect standard mobile devices to a mobile operator’s network using residential DSL or cable broadband connections.A Home Node B (HNB), is the 3GPP's term for a 3G femtocell. A Node B is an element of a 3G macro Radio Access Network (RAN). A femtocell performs many of the function of a Node B, but is optimized for deployment in the home.

The new standard
The new standard covers the following main areas:

Network architecture
Radio & interference aspects
Femtocell management / provisioning and security

In the proposed network architecture, the interface between femtocells and gateways in the network core re-uses existing 3GPP UMTS protocols and extends them to support the needs of high-volume femtocell deployments. The new standard has adopted the Broadband Forum’s TR-069 management protocol which has been extended to incorporate a new data model for femtocells developed collaboratively by Femto-Forum and Broadband Forum members and published by the Broadband Forum as Technical Report 196 (TR-196).

LTE SON

2010-04-10T14:43:00.002+05:30

SON stands for Self Organizing Networks. It is one of the key advantages of the LTE and is being standardized by 3GPP in Release8, Release 9 and beyond. LTE SON will leverage on the network intelligence, automation and network management features in order to automate the configuration and optimization of wireless networks, thereby lowering costs and improving network performance and flexibility.

Why SON
Newer and better classes of mobile devices are coming out to the market thereby providing a push to the total wireless data usage. Consequently, the wireless service providers are forced to offer support to a growing number of higher-bandwidth data applications and services on their networks,while simultaneously keeping the delivery cost as low as possible. This growth in wireless data demand is so rapid that it is also expected to increase Radio Access Network complexity through additions of femtocells, picocells, as well as WiFi access points in order to drive increases in coverage and capacity. All these demands put a lot of pressure upon service providers in the areas of network performance and operations. The traditional network management has been proved to be quite inadequate for managing the growing data volume and network complexity in a cost-effective manner.

SON
Self-Configuration by itself is quite a broad concept.It involves several distinct functions that are covered through specific features like the Automatic Software Management,Self Test and Automatic Neighbor Relation configuration. Self-Configuration of networks are expected to reduce the amount of manual processes involved in the planning, integration and configuration of new eNodeBs. This helps in faster network deployment and also paves way for reduced costs for the operator. SON provides a more integral inventory management system that has lesser volume of human errors. The Self - Configuration actions takes place after the eNodeB is installed, and plugged to the power line and to the transport link.On power on, it will boot and perform a Self Test, followed by a set of self-discovery functions. After the self-discovery,auto-configuration of the transport link happens and connections are established with the corresponding servers. After the node is self-configured one more self-test covering all hardware and software functions is run and report is presented to the network management node.

Current status
Current LTE standards do incorporate functionality related to the self- configuration, including Automatic Software Management Self Test, Automatic Neighbor Relation and Automatic Inventory Management.3GPP has not fully specified a standardized self-configuration functionality as of now. So it is natural that the first versions of the eNodeB self-configuration functionality will be basically having vendor dependent aspects, as .

Universal Charging Solution

2010-04-05T17:44:00.002+05:30

In partnership with many leading mobile operators and manufacturers, the GSM Association has announced a commitment to implementing a cross-industry standard for a Universal Charging Solution (UCS) for new mobile phones. The main objective is to adopt a common format for mobile phone charger connections and energy-efficient chargers, world-wide. The initiative aims at making chargers which have advantages like

reduce standby energy consumption
eliminate thousands of tonnes of duplicate chargers
enhance the end-user experience for mobile customers

This has been further endorsed by the ITU also. The European Commission recently reached an agreement with major phone providers for the UCS to work with all data-enabled phones sold in the European Union.The product definition includes common power supply with a detachable cable based on USB-IF standards.

UCS advantage
UCS is based on a Common Power Supply (CPS) having atleast a 4-star or higher energy rating. It will meet all efficiency regulations. With UCS in place, fewer chargers need to be manufactured each year which helps in reducing greenhouse gases produced in making and delivery of the replacement chargers. The widespread adoption of a Universal Charging Solution (UCS) is expected to result in:

up to 50% reduction in standby energy consumption
elimination of up to 51,000 tonnes of duplicate chargers
enhance the end user experience and simplify the charging of mobile devices

For the consumer, charging a mobile device will simplify the end-user experience. Consumers will be able to carry fewer chargers and charge mobile phones anywhere from any available charger. Consumers will also be able to re-use chargers even when they upgrade their phone or if they have different mobile phones from different manufacturers but still want to carry and use a single charger.

The inititative was launched in 2009 and the group expects a UCS world by 2012.

For a product overview, visit GSMA site.

Telecom - 10 years from Now...

2010-03-26T10:27:00.002+05:30

Broadband is a term that has changed the world around since the word Television has been coined. It has changed the way we live, work, the way world itself works. The future definitely belongs to broadband and more importantly, mobile broadband. Almost all the nations across the world are in the process of upgrading their national Telecom infrastructure. The winner will be those who work pro-actively and have the vision for what will the future look like, 10 years from now.

Its fascinating that our limitations are mostly due to our limited vision of future. Not everyone can predict the opportunities available to our industry. The vast possibilities of a great future will only become a reality if we make ourselves responsible for that future.

2020 shaping Ideas
What will life be like in 2020? What will consumers, enterprises and society want from communications in 2020? How will the world evolve? What habits and needs will people have? What kinds of technologies will they use to make life easier? Life in 2020 reflects Ericsson’s view of what the world of communications might look like in the future.

2020-shaping ideas is an Ericsson initiative worth following. It reflects the views of different thinkers, prominent personalities on how broadband and 24-hr connectivity will shape our life in the future. The site itself has an interesting design with lot of clips attached each one presenting a different view of the life 2020. The one by Adrian Bowyer on the Rep Rap machine using which you can download physical objects is very interesting. The concept itself is an amazing one.

More on this at the Ericsson site "2020-shaping ideas"

Check it out. The future is really promising!!!!

VoLTE - Voice over LTE

2010-03-19T14:26:00.002+05:30

The need for a low-cost, low-risk approach for bringing Voice to LTE deployments have lead to an initiative by T-Mobile Germany and some of the leading equipment vendors (Cisco, Kineto, Motorola, Ericsson, and Alcatel-Lucent etc.) to enable transmission of voice over LTE networks. The solution will enable the delivery of traditional circuit switched services such as voice, SMS and VMS over LTE. The overall objective is to enable GSM/UMTS operators to re-use existing equipment to deliver circuit based services over LTE and hence reduce costs.The advantage is that it will minimize the number of elements required to deploy VoIP over LTE. The architecture will also support handoff of circuit based services between GSM/UMTS and LTE networks. This means operators with legacy networks can migrate some of their network to LTE, still supporting legacy services in rural and suburban areas. It will also enable roaming between LTE and GSM/UMTS networks.

Approaches
LTE (Long-Term Evolution) is shaping up as the choice of most mobile operators worldwide for next-generation networks, but it is not designed currently to carry voice or SMS traffic in the same way today's carrier networks do. This is basically because it uses a packet-based IP (Internet Protocol) data network. When looking at the options for ways of carrying voice over LTE, a number of possible solutions were arrived at. Equipment vendors and carriers have been lining up around two approaches to handle voice on LTE, called VoLGA (Voice over LTE via Generic Access) and One Voice.CSFB, Circuit Switched Fall Back is a less popular alternative.

Nokia Siemens Networks claims to have carried out a voice call over LTE networks at its research and development centers, recently. The call used the company's Fast Track VoLTE technology, which it said is aligned with the One Voice initiative. Meanwhile, Deutsche Telekom also claimed it had completed an LTE voice call using VoLGA technology, using independent VoLGA-based systems from Kineto Wireless and Alcatel-Lucent. Kineto has announced a new release of software for its access gateway that the company said supports the VoLGA Forum's specification.

The One Voice
The One Voice profile for Voice over LTE is proposed by a collaboration between over forty operators including: AT&T, Verizon Wireless, Nokia and Alcatel-Lucent. At the 2010 GSMA Mobile World Congress, GSMA announced that they were supporting the One Voice solution to provide Voice over LTE. VoLTE, Voice over LTE is an IMS-based specification. Adopting this approach will enable it to integrate into the suite of applications that will become available on LTE.

VoLGA
The VoLGA standard is based on the existing 3GPP Generic Access Network (GAN) standard. It aims at enabling LTE users to receive a consistent set of voice, SMS (and other circuit-switched) services as they transition between GSM, UMTS and LTE access networks.

CSFB, Circuit Switched Fall Back
The circuit switched fallback(CSFB) LTE has been standardised under 3GPP specification 23.272. LTE CSFB uses a variety of processes and network elements to enable the circuit to fall back to the 2G or 3G connection before a circuit switched call is initiated. It also allows for SMS to be carried since it is essential for set-up procedures for cellular telecommunications. The handset uses an interface known as SGs which allows messages to be sent over an LTE channel.

In the future, mobile operators with LTE will have to carry voice and SMS traffic alongside data on a single network using LTE. This will make more efficient use of radio spectrum. But the transition to that point is still very far!

Evolving HSPA : HSPA+

2010-03-01T13:09:00.002+05:30

An evolution of HSPA has been specified based on the studies, which added multiple input/ multiple output (MIMO) antenna capability and 16QAM (Uplink)/ 64QAM (Downlink) modulation. The improvements in the radio access network for continuous packet connectivity will help the evolving architecture - HSPA+ - achieve uplink speeds of 11Mbps and Downlink speeds of 42Mbps. HSPA+, also known as Evolved High-Speed Packet Access is a wireless broadband standard defined in 3GPP release 7. The 3GPP roadmap from HSPA to HSPA+ and then to LTE has been well defined in standards development work with the final closing of Release 8.

HSPA+
HSPA+ is a simple upgrade to HSPA networks existing today. HSPA+ provides a performance advantage for the GSM-HSPA operators providing OFDMA equivalent performance in 5X5 MHz spectrum allocations
with only incremental investment.HSPA+ doubles the data capacity over HSPA and over WCDMA, it offers more than double voice capacity. Lower latency is being projected as one of the key advantages. Higher order modulation schemes are utilized to enhance the data rates. HSPA+ networks are likely to co-exist with LTE networks during the initial years, after which the oprerators may want to shift to the next level of efficiency. The discontinuous transmit/receive feature allows the device to gate off the control channels when there is no user data to send. Similarly the receiver is turned off at certain agreed intervals when there is no downlink information to the device. Such a synchronized operation allows the device to shut off its transmitter and receiver blocks completely, which significantly improves the device battery life for voice over HSPA services.

HSPA+ thus provides an excellent technology evolution path from HSPA, enabling operators to maximize their return on existing investments.

3GPP networks : shrinking the globe further

2010-02-17T10:07:00.000+05:30

A new survey by the Global mobile Suppliers Association (GSA) published recently confirms the increased penetration of GSM/EDGE systems.Operators in a large number of regions have made significant investments to enhance the capacity and coverage of their existing networks.The common trend has been to extend EDGE capabilities to the full GSM coverage areas.After the first commercial EDGE network deployment in June 2003, GSA estimates that over 80% of GPRS operators have committed to the EDGE enhancement.EDGE network capabilities are evolving as part of the 3GPP specifications. Commercial EDGE Evolution solutions are now available which increase EDGE network downlink and uplink data speeds and reduce latency, extending mobile broadband availability cost-effectively.

On the wireless broadband front the UMTS Forum confirms that subscriptions to 3G/UMTS networks have reached 500 million. The milestone has been achieved in just eight years after the world’s first commercial 3G/WCDMA network was deployed by Japanese operator NTT DOCOMO. According to data from wireless Intelligence (http://www.wirelessintelligence.com), there are now over 300 UMTS family networks worldwide.The total includes almost 40% of 3G/UMTS subscribers who are enjoying an enhanced mobile broadband experience via HSPA networks. Over 35 HSPA+ networks are now commercialized, boosting theoretical peak data rates as high as 28 Mb/sec.It is amazing to note that it took fixed telephone networks over a century to reach their first half billion customers. GSM networks have achieved the same milestone in only a decade!. This clearly is a reflection of the modern world's ever-growing need to stay connected. WCDMA and now HSPA are delivering the same services at a cost that made GSM a global success. Building on the success of the WCDMA/HSPA systems, LTE is expected to offer end-users an even faster, more satisfying mobile Internet experience, while attracting a new wave of players from new frontiers.

LTE is IMT advanced - 3GPP

2010-02-03T09:54:00.002+05:30

In September 2009 the 3GPP Partners made a formal submission to the ITU proposing that LTE Release 10 and successors (called LTE-Advanced) be evaluated as a candidate for IMT-Advanced. This suggests that the next generation or truly 4G mobile WiMAX is likely to be a specification that is never implemented on a significant scale. This news may be confusing to those who thought that lot of operators have already deployed "4G" WiMAX networks. Since the backwards compatibility of 802.16m with current 802.16e is being emphasized, the hopes that somehow LTE and mobile WiMAX might be merged, or that the latter could become the TDD version of LTE has been put to rest. Operators now installing and committed to 802.16e should be very wary about the long term roadmap for mobile WiMAX technology. They should ensure that they do not lock themselves into this technology for very long, and should be preparing paths for migration to LTE. Intel has been a champion of WiMAX since its inception. But Intel’s future in mobile product markets is much more dependent upon its ability to carve out a substantial share for its low power processors in this business and to have its components incorporated into devices that will work on 3GPP networks, than it is upon the supply of chipsets for WiMAX wireless modems. LTE supports voice and efficient support of voice was one of the key considerations in designing LTE. The voice solution for LTE is IMS VoIP and it is fully specified.

Single Carrier FDMA - for 4G wireleess

2010-01-27T10:48:00.002+05:30

Over the last decade, the bit rates achieved in wireless communications systems have increased steadily.
TDMA and CDMA has been the major technologies in multiple access. The highest bit rates in commercially deployed wireless systems are achieved by means of Orthogonal Frequency Division Multiplexing (OFDM). The next advance in cellular systems, under investigation by the Third Generation Partnership Project (3GPP), also anticipates the adoption of OFDMA to achieve higher bit rates. Single carrier frequency division multiple access (SC-FDMA), a modified form of Orthogonal FDMA (OFDMA), is a promising technique for high data rate up-link communications in future cellular systems.

SC FDMA
An SC system transmits a single carrier, modulated, for example, with QAM, at a high symbol rate. The transmitters use different orthogonal subcarriers to transmit information symbols. The transmission is sequential, which reduces the variations in the transmitted signal envelope. This results in a lower peak-to-average-power ratio. Frequency domain equalization os carried out to counter the severe delay spreads the signal might encounter. The advantages may be listed as:

Small variations in the instantaneous power of the transmitted signal
Possibility for low-complexity high-quality equalization in the frequency domain.
Possibility for FDMA with flexible bandwidth assignment.
SC-FDMA can be seen as normal OFDM with a DFT-based precoding

SC-FDMA transmitter and receiver
The block diagram of the SC-FDMA receiver and transmitter is given the figure. The figure is self-explanatory. Similar to OFDM modulation, DFTS-OFDM relies on block-based signal generation.
By adjusting the transmitter DFT size and the size of the block of modulation symbols the nominal bandwidth of the DFTS-OFDM signal can be dynamically adjusted.

Throughput
Information throughput is another indication of the system performance. Here the throughput depends on the manner in which information is applied to the subcarriers. The two main methods are localized and distributed. The benefit of distributed system, compared to localized, is the possibility for additional frequency diversity as even a low-rate distributed signal can be spread over a potentially very large overall transmission bandwidth. It has been shown that the SC-FDMA can be tuned to achieve data rates in excess of 40Mbps.

Future
Within a specific SC-FDMA system configuration, there are many design and operational choices that affect performance in a complex manner . The impact of channel estimation error on the throughput performance of SC-FDMA is still not understood clearly. Still, SC-FDMA is a promising technique for high data rate
uplink communication in future cellular systems.

Operator ID for WMAN

2010-01-05T10:54:00.002+05:30

IEEE Std 802.16 defines a 24-bit Operator ID to identify the operator of an IEEE 802.16 base station. The 24-bit Operator ID shall be assigned as an IEEE 802.16 Operator ID by the IEEE Registration Authority. The IEEE Registration Authority is the sole authorized number space administrator for this function. This Operator ID (OpID) is combined with an additional 24-bit programmable field to define the 48-bit Base Station ID. Provided that the operator assigns unique numbers to the least significant 24 bits of the Base Station Identifier, this results in a globally unique Base Station Identifier, as long as the OpID is globally unique.

IEEE 802.16 Operator ID & Base station ID
The IEEE 802.16 Operator ID is a sequence of 24 bits. It is administered by the IEEE Registration Authority. A Base Station ID is defined as a sequence of 48 bits. The first 24 bits take the values of the 24 bits of the Operator ID.

Operator ID Usage
The Operator ID referenced in the assignee's IEEE Registration Authority Assignment is described as a 24-bit globally assigned Operator ID and as an integral part of a 48-bit globally assigned Base Station ID. An Operator ID assignment allows the operator to generate approximately 16 million Base Station IDs, by varying the last three octets.

The method that an operator uses to ensure that no two of its Base Stations carry the same ID will, of course, depend on the assignment process and the operator's philosophy. However, the network selection algorithms may expect Base Stations to have unique IDs. The ultimate responsibility for assuring that expectations and requirements are met, therefore, lies with the operator of the Base Station.

OFDM - Accelerating data rates

2009-12-21T11:12:00.002+05:30

Frequency division multiplexing (FDM) is a technology that transmits multiple signals simultaneously over a single transmission path, such as a cable or wireless system. Each signal travels within its own unique frequency range (carrier), which is modulated by the data. Orthogonal FDM (OFDM) spread spectrum technique distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the "orthogonality" in this technique which prevents the demodulators from seeing frequencies other than their own. It is identical to Coded FDM and the Discrete Multitone (DMT) modulation.

Orthogonality
In OFDM, the sub-carrier frequencies are chosen so that the sub-carriers are orthogonal to each other, meaning that cross-talk between the sub-channels is eliminated and inter-carrier guard bands are not required. This greatly simplifies the design of both the transmitter and the receiver. A separate requirement for different filters is thus eliminated. This results in high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. But this also means high accuracies in synchronization between transmitter and receiver is required.

OFDM exhibits lower multi-path distortion (delay spread), since the sub-signals are sent at lower data rates. Because of the lower data rate transmissions, multi-path-based delays are not nearly as significant as they would be with a single-channel high-rate system. For example, a narrow band signal sent at a high rate over a single channel will likely experience greater negative effects from delay spread because the transmitted symbols are closer together. In fact, the information content of a narrow band signal can be completely lost at the receiver if the multi path distortion causes the frequency response to have a null at the transmission frequency. The use of the multi-carrier OFDM significantly reduces this problem.

Simple Implementation
The orthogonality allows for efficient modulator and demodulator implementation using the FFT algorithm on the receiver side, and inverse FFT on the sender side. Although the principles and some of the benefits have been known since the 1960s, OFDM is popular for wideband communications today by way of low-cost digital signal processing components that can efficiently calculate the FFT.

Elimination of intersymbol interference
One key principle of OFDM is that since low symbol rate modulation schemes i.e. where the symbols are relatively long compared to the channel time characteristics suffer less from inter symbol interference caused by multi path propagation, it is advantageous to transmit a number of low-rate streams in parallel instead of a single high-rate stream. Since the duration of each symbol is long, it is feasible to insert a guard interval between the OFDM symbols, thus eliminating the inter symbol interference. The cyclic prefix, which is transmitted during the guard interval, consists of the end of the OFDM symbol copied into the guard interval, and the guard interval is transmitted followed by the OFDM symbol. The reason that the guard interval consists of a copy of the end of the OFDM symbol is so that the receiver will integrate over an integer number of sinusoid cycles for each of the multi paths when it performs OFDM demodulation with the FFT.

Simplified equalization
The effects of frequency-selective channel conditions, for example fading caused by multipath propagation, can be considered as constant (flat) over an OFDM sub-channel if the sub-channel is sufficiently narrow-banded, i.e. if the number of sub-channels is sufficiently large. This makes equalization far simpler at the receiver in OFDM in comparison to conventional single-carrier modulation. The equalizer only has to multiply each detected sub-carrier (each Fourier coefficient) by a constant complex number, or a rarely changed value.

Importance of channel coding
Channel coding is used in most cases of digital communication and especially in case of mobile communication. Channel coding implies that each bit of information to be transmitted is spread over several, often very many, code bits. If these coded bits are then, via modulation symbols, mapped to a set of OFDM subcarriers that are well distributed over the overall transmission bandwidth of the OFDM signal, each information bit will experience frequency diversity in case of transmission over a radio channel that is frequency selective over the transmission bandwidth, despite the fact that the subcarriers, and thus also the code bits, will not experience any frequency diversity. Thus, in contrast to the transmission of a single wideband carrier, channel coding (combined with frequency interleaving) is an essential component in order for OFDM transmission to be able to benefit from frequency diversity on a frequency-selective channel.

OFDM for Access control
OFDM can also be used as a user-multiplexing or multiple-access scheme, allowing for simultaneous frequency-separated transmissions to/from multiple mobile terminals. In the downlink direction, OFDM as a user-multiplexing scheme implies that, in each OFDM symbol interval, different subsets of the overall set of available subcarriers are used for transmission to different mobile terminals. Similarly, in the uplink direction, OFDM as a user-multiplexing or multiple access scheme implies that, in each OFDM symbol interval, different subsets of the overall set of subcarriers are used for data transmission from different mobile terminals.

Issues
A drawback of OFDM modulation, as well as any kind of multi-carrier transmission, is the large variations in the instantaneous power of the transmitted signal. Such power variations imply a
reduced power-amplifier efficiency and higher power-amplifier cost. This is especially critical for the uplink, due to the high importance of low mobile-terminal power consumption and cost. Several methods have been proposed on how to reducethe large power variations of an OFDM signal. However, most of these methods have limitations in terms of to what extent the power variations can be reduced. Furthermore, most of the methods also imply a significant computational complexity and/or a reduced link performance.

Femtocells - The new cellular concept

2009-12-08T09:56:00.003+05:30

Femtocells are destined to transform the way mobile operators build their cellular networks and grow their coverage and capacity. Femtocells are small base stations operating in the usual, licensed bands. They are very small, require very low power transmitters and can be even placed in individual homes. This concept is very different from the usual cellular concept.

Advantages
Most important advantage is the improved coverage. Since the target is only a small set of users, providing them reliable coverage and a larger bandwidth is easy. Another advantage is the cost saving involved. The need to upgrade the capacity with increasing subscriber base is easily met with femtocells.

Issues

New levels of Interference mitigation and management is required, including macro to femto, femto to femto, and femto/handset interference.
System selection, Integration with the operator’s core network and access control becomes all the more complicated.
Security related aspects need to be taken care of.
Network and frequency planning will be more sophisticated.

In the past couple of years, the technical community has been working these issues, and the advances have
been significant.

Next generation Mobile WiMAX

2009-09-06T15:42:00.002+05:30

WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multi-point links to portable and fully mobile internet access. Mobile WiMAX enables the convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. The next-generation mobile WiMAX will be capable of data-transfer rates in excess of 1 Gbps. It is expected to support a wide range of high quality and high capacity IP-based services and applications while maintaining full backward compatibility with the existing mobile WiMAX systems.

Architecture features
IEEE 802.16m (new version of the 802.16) uses OFDMA as the multiple access scheme in the DownLink and UpLink. It supports both time-division duplex (TDD) and frequency-division duplex (FDD) schemes including the half-duplex FDD (HFDD) operation of the mobile stations in the FDD networks. The frame structure attributes and base-band processing are common for both duplex schemes. The modulation schemes supported include quadrature-phase shift-
keying (QPSK), 16-QAM, and 64-QAM.To overcome the issue of performance of adaptive modulation, a constellation rearrangement scheme is utilized. The next generation mobile Wimax suppports advanced multi-antenna techniques like single and multiuser MIMO, alongwith various transmit diversity schemes. The MAC features are an extension of the existing standard.

The next gen system is designed to provide state-of-the-art mobile broadband wireless access in the next decade and to satisfy the growing demand for advanced wireless multimedia applications and services.

MIMO - The Basics

2009-07-26T11:08:00.001+05:30

Multiple-input multiple-output (MIMO) systems are today regarded as one of the most promising research areas of wireless communications. This is due to the fact that a MIMO channel can oﬀer a signiﬁcant capacity gain over a traditional single-input single-output (SISO) channel.

MIMO overview

MIMO is effectively a radio antenna technology as it uses multiple antennas at the transmitter and receiver to enable a variety of signal paths to carry the data, choosing separate paths for each antenna to enable multiple signal paths to be used. The increase in spectral efficiency offered by MIMO systems is based on the utilization of space (or antenna) diversity at both the transmitter and the receiver.
It is found between a transmitter and a receiver, the signal can take many paths. Additionally by moving the antennas even a small distance the paths used will change. The variety of paths available occurs as a result of the number of objects that appear to the side or even in the direct path between the transmitter and receiver. Previously these multiple paths only served to introduce interference. By using MIMO, these additional paths can be used to increase the capacity of a link.

Basic concept of MIMO wireless schemes

One of the core ideas behind MIMO wireless systems space-time signal processing in which time (the natural dimension of digital communication data) is complemented with the spatial dimension inherent in the use of multiple spatially distributed antennas, i.e. the use of multiple antennas located at different points. Accordingly MIMO wireless systems can be viewed as a logical extension to the smart antennas that have been used for many years to improve wireless.

MIMO summary

As a result of the use multiple antennas, MIMO wireless technology is able to considerably increase the capacity of a given channel while still obeying Shannon's law. By increasing the number of receive and transmit antennas it is possible to linearly increase the throughput of the channel with every pair of antennas added to the system. This makes MIMO wireless technology one of the most important wireless techniques to be employed in recent years. As spectral bandwidth is becoming an ever more valuable commodity for radio communications systems, techniques are needed to use the available bandwidth more effectively. MIMO wireless technology is one of these techniques.

The Race to 4G....

2009-06-11T09:59:00.000+05:30

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
Whereas WiMAX emerged from the WiFi IP paradigm, 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 the likes of Sprint ClearWire and 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!!!

A faster Internet?

2009-05-06T14:15:00.002+05:30

The Internet is founded on a very simple premise: shared communications links are more efcient than dedicated channels that lie idle much of the time. And so we share. We share local area networks at work and neighborhood links from home. And then we share again—at any given time, a terabit backbone cable is shared among thousands of users surfng the Web, downloading videos.. But there’s a profound flaw in the protocol that governs how people share the Internet’s capacity. The protocol allows you to seem to be polite, even as you elbow others aside, taking far more resources than they do.

You might be shocked to learn that the designers of the Internet intended that your share of Internet capacity would be determined by what your own software considered fair. They gave network operators no mediating role between the conflicting demands of the Internet’s hosts. The Internet’s primary sharing algorithm is built into the Transmission Control Protocol, a routine on your own computer that most programs . TCP is one of the twin pillars of the Internet, the other being the Internet Protocol, which delivers packets of data to particular
addresses. The two together are often called TCP/IP.

Forcing the way!
TCP routine constantly increases your transmission rate until packets fail to get through!Then TCP very politely halves your bit rate. The mechanism is termed "binary exponential back-off". What a name isn't it? All other TCP routines around the Internet behave in just the same way, in a cycle of taking, then giving, that fills the pipes while sharing them equally.

Fair play?
An equal bit rate for each data flow is likely to be extremely unfair, by any realistic definition. It’s like insisting that boxes of food rations must all be the same size, no matter how often each person returns for more or how many boxes are taken each time. But any programmer can just run the TCP routine multiple times to get multiple shares. It’s much like getting around a food-rationing system by duplicating ration coupons. This trick has always been recognized as a way to sidestep TCP’s rules—the frst Web browsers opened four TCP connections!

The solution!
There’s a far better solution- according to Bob Briscoe. It would allow light browsing to go blisteringly fast but hardly prolong heavy downloads at all. The solution comes in two parts. It begins by making it easier for programmers to run TCP multiple times—a deliberate break from TCP-friendliness. They set a new parameter—a weight—so that whenever your data
comes up against others all trying to get through the same bottleneck, you’ll a share of the total. The key is to set the weights high for light interactive usage, like surfing the Web, and low for heavy usage, such as movie downloading.

Imagine a world where some Internet service providers offer a deal for a fat price but with a monthly congestion-volume allowance. Note that this allowance doesn’t limit downloads as such; it limits only those that persist during congestion. If you used a peer-to-peer program like BitTorrent to download 10 videos continuously, you wouldn’t bust your allowance so long as your TCP weight was set low enough. Your downloads would draw back during the brief moments when flows came along with higher weights. But in the end, your video downloads would finish hardly later than they do today.

Reference

http://www.cs.ucl.ac.uk/staf/bbriscoe/projects/refb/
www.spectrum. ieee.org

Sustaining the Growth of Internet

2008-11-30T08:17:00.002+05:30

Widespread claims of Internet traffic doubling every three or four months are exaggerated. Actual U.S. backbone traffic appears to be doubling once a year.“Traffic doubling each year” refers here to any growth rate between 70 and 150% per year. Imprecision caused by incomplete statistics.There was a slowdown in growth, but that occurred in 1997. Ever since, growth has been steady and rapid, although not as astronomical as popular mythology holds. Even if the problems related to high speed fibre networks are solved, there appears to be a limit at which traffic is likely to grow, caused by the many other feedback loops operating on different time scales.

In a world-first model of internet power consumption, University of Melbourne researchers have been able to identify the major contributors to Internet power consumption as the take-up of broadband services grows in the coming years.

"It has now become clear that the exponential growth of the Internet is not sustainable, "said Dr Hinton.The result indicates that, even with the improvements in energy efficiency of electronics, the power consumption of the Internet will increase from 0.5% of today's national electricity consumption to 1% by around 2020.

"The growth of the Internet, IT broadband telecommunications have opened up a wide range of new products and services. New home services include Video on Demand, web based real-time gaming, social networking, peer-to-peer networking and more. For the business community, new services may include video conferencing, outsourcing and tele-working. To support these new high-bandwidth services, the capacity of the Internet will need to be significantly increased. If Internet capacity is increased, the energy consumption, and consequently the carbon footprint of the Internet will also increase", Dr Hinton quoted.

Reference:
http://www.sciencedaily.com /releases/2008/11/081125113116.htm

NFC - The new mobile mantra?

2008-07-05T20:39:00.000+05:30

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.

International Telecommunication Union Approves WiMAX Technology as New IMT-2000 Standard

2008-04-22T22:57:00.000+05:30

WiMAX Technology Inclusion to Expand Operators Global Access

Portland October 19, 2007 The WiMAX Forum is pleased to recognize the decision of the Radiocommunication Sector of the International Telecommunication Union (ITU-R) to include WiMAX technology in the IMT-2000 set of standards. This decision is of global importance to operators who look to ITU to endorse technologies before they invest in new infrastructure. The decision to approve the WiMAX Forum's version of IEEE Standard 802.16 as an IMT-2000 technology significantly escalates opportunities for global deployment, especially within the 2.5-2.69 GHz band, to deliver Mobile Internet to satisfy both rural and urban market demand.

"This is a very special and unique milestone for WiMAX technology," said Ron Resnick, president of the WiMAX Forum. "This is the first time that a new air interface has been added to the IMT-2000 set of standards since the original technologies were selected nearly a decade ago. WiMAX technology currently has the potential to reach 2.7 billion people. And today's announcement expands the reach to a significantly larger global population."

From the initial application made at the ITU-R WP8F meeting in January of this year to this week's meeting of the Radiocommunications Assembly in Geneva, Administrations, industry and ITU have worked together to achieve this groundbreaking decision.

"It gives me great satisfaction to observe that the ITU Radiocommunication Sector continues to be responsive to the most pressing needs of the wireless industry," said Valery Timofeev, Director of the ITU Radiocommunication Bureau.

With WiMAX technology approved as a new IMT-2000 specification, the WIMAX ecosystem will benefit from greater economies of scale, thus reducing the already low cost to deliver broadband wireless services to include VOIP as well as the multiple services expected from wireless broadband Internet access.

Originally created to harmonize 3G mobile systems and to increase opportunities for worldwide interoperability, the IMT-2000 family of standards will now support four different access technologies, including OFDMA (includes WiMAX), FDMA, TDMA and CDMA.

"3G solutions based upon technologies such as W-CDMA, CDMA-2000, and TD-SCDMA technologies were already included in the IMT-2000 set of standards," said Resnick. "With WiMAX technology now included, it places us on equal footing with the legacy-based technologies ITU-R already endorses." The bottom line is that operators across the globe now have the freedom to select the right technology to best meet their business and regional needs."

source: Wimax forum