Emerging Technologies for Virtual Instrumentation

SDR Architectures--Key Features

2010-06-11T06:51:00.001-05:00

The advances in SDR technologies require a new architectures to support the reconfigurability of those technologies. In this paper the authors show several architecture setups. Key features of any architecture includes variable bandwidth, sufficient dynamic range, fast retuning and reconfiguration, minimized cost, and energy efficient.

Best regards,
Hall T.

Primer on SDR continued--Cognitive Radio

2010-06-04T09:41:00.000-05:00

In continuing last week's post on SDR primer, this week we look at Cognitive Radio which is "a radio that senses or is aware of its operational environment and can dynamically and autonomously adjust its radio operating parameters accordingly" according to Joe Mitola. Basically, the Cognitive radio senses its envionment and learns how to adapt to its environment. While SDR and Cognitive Radio can be a potential panacea for every wireless problem, it appears to be ideally suited for interoperability of radios and reducing interference. A software defined radio can come in various forms such as reconfigurable (can be changed by the user), to policy -based (change is based on a predetermined set of configurations), to cognitive radio (can be changed based on the environment).

Best regards,
Hall T.

SDR Advantages and Disadvantages

2010-05-28T10:00:00.001-05:00

For those unfamiliar with software defined radio and related topics, here's a great tutorial by VT. The slide set does a good job in defining SDR by showing how the physical layer is moved from hardware into software and how the radio adapts to its environment although that part leans more to the Cognitive Radio side. The advantages of SDR include reduced component cost because hardware specific components are replaced by DSPs and FPGAs. The number of components tends to be lower. DSP components can compensate for problems in other areas of the system. Disadvantages include power consumption, security, and overall cost.

The key difference between traditional radios and software defined radios is that the latter senses their environment and adapt to it. This is important particularly to government agencies such as the FCC who is in the process of reallocating spectrum usage in the TV bands. There's a shift away from rigid, spectrum allocations to a demand-based approach to maximum the usage in that band. Currently, spectrum usage in most bands in the USA range from .3 to 3%. As the need for more spectrum grows, a new paradigm will be needed to supply this bandwidth.

Best regards,

Hall T.

Using SDR in Pico Satellites

2010-05-21T06:46:00.001-05:00

Software defined radio is not just for mobile phone communications. It finds applications in numerous other places and for different reasons. One of the more intriguing applications is that in pico satellites. Pico satellites are small satellites developed by university groups for research and education purposes which catch a ride on rocket and space shuttle flights. Once out of the earth's atmosphere, they are tossed out into the ether and start their mission. In this application SDR is used for positioning and navigation. By using SDR techniques, the positioning system was made lighter, smaller, and most importantly with lower power consumption.

Best regards,

Hall T.

Power Management in SDR

2010-05-14T09:26:00.000-05:00

SDR brings a great deal of resource-intensive processing to the application in order to handle the variety of waveforms, modulation schemes, and other RF functions. This additional processing comes at the expense of greater power requirements. This drives the designer to make performance/power tradeoffs in the design of SDR systems. Power management in Software Defined Radio is a major concern since most SDR applications use more power than hardware radios. Also, field deployed units need to conserve power since they typically run on batteries. The RF front ends are typically overpowered as they need to generate RF patterns across a wide range. Finally, SDR applications tend to generate excessive heat which needs to be dissipated.

Power management is a key success factor in software-defined radio applications due to the portable nature of most target systems. In this paper the authors propose a horizontal layering of the hardware along with software-specific APIs to provide component-level control over power management. By dividing the system into components, power consumption can be customized for the application. For example, a signal processing intensive application could shut down other functions while the FPGA/Processor works. The user can turn off functions to increase the battery lifetime in a mission critical operation.

Best regards,
Hall T.

Dynamic Spectrum Access Regulatory Models

2010-04-15T10:45:00.001-05:00

The current model of RF Frequency management is to assign frequency bands to groups and applications. This mitigates the problem of interference and controls to some extent the usage of the RF spectrum. In many of the allocated bands, the usage of the alloted spectrum runs from 0.03 to 3%. As spectrum becomes scarce due to a growing use of existing applications and new applications requiring additional bandwidth come on the market, the spectrum access model is coming under scrutiny. A newer Dynamic Spectrum Access Regulatory model is coming into focus. In this model, the spectrum is not allocated but rather users are allowed to make use of a frequency band if they can do so without interfering with other users in that band.

The key conference in this area is the IEEE Dyspan (Dynamic Spectrum Access Network ). The purpose of the group is

" to expand collective understanding of complex next-generation wireless systems focused on using RF spectrum more efficiently and dynamically. This includes advancing both cutting edge technical and multidisciplinary research as well as practical experience related to building a healthy industry/regulatory ecosystem for the commercialization of smart radio system technologies.

As networks and devices increasingly gain intelligence and "cognitive" capabilities, and as regulators around the world seek to enhance spectrum utilization through exploiting areas such as "white spaces", dynamic decentralized access is becoming one of the most important, but most complex topics in wireless communications development. IEEE DySPAN 2010 will continue investigation of decentralized spectrum access and focus on approaches for highly scalable dynamic optimization of wireless spectrum use. "

There are several initiatives to further the Dynamic Spectrum Access effort. One is the Potential Alliance for World-wide Dynamic Spectrum Access by the New America Foundation. The group seeks to foster better working relationship between military, consumer, and public-safety groups.

Best regards,

Hall T.

What will the "IBM PC" of SDR Look Like?

2010-04-09T06:48:00.001-05:00

The IBM PC revolutionized the personal computer industry by bringing standards to a low-cost personal computer platform. It became the dominant design drawing from several industry-proven technical solutions and covering many market segments. It held the right tradeoff balance between technical performance and market requirements. Up until the entry of the IBM PC the market was flush with competing standards and methodologies. An "IBM PC" solution will eventually come to the SDR world. Software defined radio will see much greater success if it can generate a dominant design solution rather than a splintered approach.

So what are the key elements that need to be synthesized into a dominant design? In this paper the authors argue that it will bring portability of waveforms, maintainability, and allow specialization of waveforms.

Another key factor will be size. It will be greatly reduced from what we see today. Just as the IBM PC took computing from the mainframe/mincomputer world down to the desktop so the next generation of SDR will go down in size. Here's one example using Gumstix.

Finally, the cost must be low and the tools widely available. Defacto standards available at low cost will drive SDR applications into new areas and create a richer set of tools for more sophisticated applications.

Best regards,

Hall T.

SDR for Public Safety Applications--Interoperability

2010-04-02T06:42:00.001-05:00

Public Safety (Fire, police, first responders, etc) are now looking at Software Defined Radio to generate interoperability among the first responders who have incompatible radios between groups. By bridging the gap through multi-band and multi-service radios. In addition to interoperability, cognitive radio techniques could also help first responder radios adapt to their environment. Consider a Katrina-situation in which the local telecom infrastructure is wiped out requiring radios to adapt to a new infrastructure. To address the issue the National Public Safety Telecomunications Council was formed to study and advise on the issues.

The key challenges in public safety applications are spectrum usage and multi-band bridging. Public radios do not use the spectrum efficiently and consequently runs out. Also first responder radios operate on different bands which must be bridged as described in this market research executive summary report.

Best regards,

Hall T.

Using SDR in base stations--No longer a Stealth Technology

2010-03-26T06:40:00.000-05:00

Software Defined Radio is no longer used as a stealth technology but has become common place in base stations roll-outs as one example in the wireless infrastructure. In this SDR Forum post one can see the long list of tools now using SDR in their technology offering. One of the original providers of SDR base stations solutions is Vanu who announced the rollout of a multi-operator radio acccess network for rural areas.

ZTE a Chinese manufacturer of base stations is currently shipping a new version of their popular base station but with SDR technologies. In addition to being more energy efficient, it will also provide SDR capabilities for working with different carriers. CSL is rolling out SDR Base Stations in Hong Kong for LTE applications using ZTE systems.

Best regards,

Hall T.

LTE Won the Race for the Next Generation

2010-03-12T06:39:00.000-06:00

Even though WiMax is rolling out in some portions of the country, LTE will be the next standard. By creating an all IP-based network it will unify mobile and fixed broadband worlds. Here's a great resource for information on 3G and 4G news.

The WiMax camp positions it the two as complementary and not competitive. In this post the author suggests that both will find a place in the market and that WiMax simply suffers from too much hype, too early in the process and is now paying the price while LTE appears to be a newcomer with all the "shininess" that comes with that role. WiMax was designed for backhaul applications and will continue in that role and LTE will find its applications as well.

While Wimax is seeing substantial growth now, the major carriers will role out LTE capabilities in the next 3 years. According to this post, the other major competitor will be HSPA.

Best regards,

Hall T.

X-Parameters--Nonlinear RF Component Characterization

2010-02-26T06:51:00.001-06:00

X Parameters ( a registered trademark of Agilent) are nonlinear network parameters that represent a superset of S-parameters. They extend S-Parameters to work with large signals and non-linear regions for characterizing RF components. To gain access to the fundamental equations, one must sign up in Agilent's partner program.

A common application is the Load-pull measurement.

Best regards,
Hall T.

Wireless TestBeds

2010-02-19T06:41:00.001-06:00

For those interested in testing out new wireless applications, the Federal Government under the Bush administration authorized the NTIA and FCC to set up a 10 MHz testbed in the 470 - 512 range as reported by the Benton Foundation. It's a common practice to carve out a portion of the spectrum to provide a testbed for developers. Clearwire did this with WiMAX in the Silicon Valley area.

University of Syracuse and Virginia Tech are leading the Wireless Grid Innovation Testbed (WGiT) with the goal of "coordinating knowledge sharing, defining key parameters for wireless grids network applications, dynamically connecting wired and wireless devices, content and users.

Another example is the Idaho National Laboratory established the Bechtel/INEEL Wireless Testbed. that offers end to end testing of next generation wireless including 3G/4G cellular and land mobile radios.

There's event a conference on the topic of building wireless test beds. You can see the current event here.

Best regards,

Hall T.

WhiteFI--WiFi Using Whitespaces

2010-02-12T06:42:00.001-06:00

Microsoft is one of the players using the whitespaces to deliver wireless access. They call it WhiteFI which is similar to WiFI but has several differences. For one it uses an adaptive spectrum assignment algorithm to handle spectrum variation. They launched the KNOWS initiative which stands for Networking over White Spaces to resolve the fundamental networking issues related to setting up base stations and forming networks. They have gone from concept to deployed system on the Microsoft campus last October. You can see more details about the project here. Microsoft has even submitted an FCC license request to take WhiteFI into the field for further experimentation. They are working with Harvard on the research. You can see their paper here.

WhiteFI has a good deal of support behind it as it promises to spur innovation to the tune of $15B/year. One example of innovation is how it will bring wireless connectivity to ever smaller nodes in further distances. For example, irrigation systems could leverage WhiteFI for wireless connectivity.

Best regards,

Hall T.

SDR Applications

2010-02-05T06:47:00.001-06:00

Software Defined Radio has been under development for many years -- primarily the military. In this whitepaper by Xilinx they position several applications on Geoffrey Moore's Crossing the Chasm model.

Smartphones follow Milcom and Satcom applications in the adoption curve. Some smartphones already use elements of SDR such as
Apple's iPhone 3G which uses the Infineon Baseband processor that has a reprogrammable DSP for baseband processing. Ericsson, Nokia, Samsung, and LG are also using similar chip sets and processing to achieve the benefits of SDR.

In the wireless infrastructure world base stations are now considered a commodity and thus price pressures require a common engineering platform targeted a multiple applications and air interfaces. ASICs can only go so far in achieving cost reductions. The next step is to apply SDR techniques. While on a single base station the cost of materials may be higher, that cost goes down when spread over several models.

In the coming years, more commercial applications spurred by the availability of spectrum without prior licensing will cross the chasm and start drawing more investment dollars.

Best regards,

Hall T.

The Key to SDR is the RF Front End

2010-01-29T06:37:00.000-06:00

Software Defined Radio will come of age in the next five years. From a niche application in the military world to an academic research topic today, SDR will become main stream in five years throughout the commercial industry. Mobility will shift beyond the handful of standards that defines its role today into an open playing field where anyone can play. The key to SDR is the RF Front End. The solution must

--be ultrawideband to handle 20 MHz to 60 GHz
--work with any softrware
--work with any waveform
--use tunable filters

Some solutions are already coming to market such as

The IMEC research center in Belgium proposes a CMOS solution to this problem. The solution promises a low-power, low-cost solution.

Microtune offers a chip for car radio applications called the MT3511 that provides a generic hardware platform to support AM/FM, digital radio, CD audio, MP3 playback, navigation, as well as connectivity for iPod®, SD card, USB and Bluetooth.

Best regards,

Hall T.

Portable Waveforms--Some Design Considerations

2010-01-22T18:07:00.000-06:00

Waveforms are just waveforms, right? Well, in the world of software defined radio a waveform is more than just what meets the eye. In the recent SDR Forum, I learned that "Portable Waveforms" consist of more than just the signal. For the JTRS program, a portable waveform consists of

--Detailed design docs
--Simulators
--Test code and data sets

Guidelines are in place for how to create portable waveforms because as this paper points out it's easier to rewrite code than to import a non-portable piece of code.

Part of the challenge in making a waveform portable is partitioning the waveform into real-time and non real-time components and then matching each component to a processor resource such as an FPGA, GPU, CPU, etc. Since hardware platforms vary widely, it's not reasonable to expect a waveform to run on any platform without some modification. Documentation including code, code hierarchy, multi thread uses, etc is required. Also, emulators and debuggers are necessary to work out how the waveform is generated and can be modified.

It's also interesting to note that IP cores specific to FPGA vendors should not be used as target platforms may not have those specific FPGA components. Clocking is another concern in that the use of multiple clocks to achieve some objective -- say lower power consumption -- may cause problems due to the target platform not having sufficient clocking resources.

Portability brings more design concerns and issues than originally meets the eye.

Best regards,

Hall T.

Smart Radio Challenge

2010-01-15T09:16:00.001-06:00

The Smart Radio Challenge is a worldwide competition in which student engineering teams design, develop and test software defined radio (SDR) that address relevant in the wireless market. In the recent SDR Forum, several competitors described their projects and the challenges they encountered.

California State University talked about unmanned aero vehicle telemetry link. Their challenge was the lack of available spectrum since an air force base was nearby. They used the Ettus Research USRP with GNU Radio software. The students developed their packet data handling protocol in Python as GNU Radio didn't provide it. They could tell the UAV to take images, generate FFTs, etc. The system had a phone home function in the event it lost communication with the ground. They used an amateur radio transceiver so it could display spectral parameters and used SDR for all signal processing. The challenges in using SDR for this project is the students had DSP but no SDR background. They started from ground zero. No one had experience with Python and no experience with real communication systems which required heavy faculty involvement. GNU Radio Grand Canyon was a good start but only goes so far. The project came out well with a successful demonstration at Edwards Air Force base. The next step will be to add target recognition and to implement the SDR on an FPGA by using the USRP.2

Virginia Tech talked about lessons from the 2008 and 2009 competitions. Their 2007 challenge was spectrum access for first responders. They chose the GNU Radio/USRP over the Lyrtech SFF because they already knew the USRP. The 2008 Challenge focused on first responders in areas with no comms infrastructure such as the Katrina disaster. They used a wireless ad hoc network approach for this one. The lessons from these two are:

Play to your strengths
Choices have unintended consequences such as system integration
Make a decision and follow through with it

For 2009 the challnege will be to locate a first rsponder based on a 406 MHz packetized beacon signal.

Carnegie Mellon presented on their Spectrum Sensing for Dynamic Spectrum Access. It's a Cognitive Radio network that takes a crowded network and sets up a secondary network within it. They first map the spectrum to find unused channels and then setup their own network. They used GNU Radio, a USRP, and Ubuntu to implement their sensing algorithm running on a series of "sensing nodes" which pass the results to a "learning center" which identifies the open spectrum slots. It then issues a beacon signal that other nodes can lock onto and then use a sub channel for creating the secondary network. They ran video, text messaging and voice messaging through the network.

Best regards,

Hall T.

Challenges for Software Defined Radio

2010-01-08T08:39:00.000-06:00

At the recent SDR Forum in Washington DC (now called the Innovative Wireless Alliance), Dr. Christer Svensson of Linkoping University in Sweden gave a keynote presentation on the challenges facing software defined radio. In his address he listed the critical requirements for SDR as

Digital protocols
Digital baseband
Receiver analog/antenna frontends
Transmitter Power Amplifiers and antenna frontend

While the first two are progressing well, the last two are not. Frontends are insufficient and power amplifiers lack multiband solutions. What's more, there's little research going on for the last two. The primary challenge here is that the receiver needs the ability to receive a weak signal in spite of a strong interfering signal given that software defined radio applications are often targeted to operate in a crowded and noisy spectrum space. For antenna/RF front ends the problem relates to antenna basics not software or waveform. One potential solution is tunable passive filters or switched filter banks. There are examples of these in the market but they are under developed at this stage.

Best regards,

Hall T.

COGNEA -- a Consortium of Companies for Utilizing the Whitespaces

2009-12-18T06:51:00.001-06:00

With the advent of commercially available white spaces in the spectrum, a consortium has formed to help drive the definition and adoption of industry-wide standards for low-power personal and portable wireless devices to operate over the TV white spaces. The consortium board consists of ETRI, HP, Philips and Samsung, with contributions from Motorola and Georgia Institute of Technology. The consortia is named CogNeA for Cognitive Networking Alliance.

The group was born out of the IEEE-802.22 standards effort. In the blog post by Mobie Sands, the author argues that 802.22 will only be competitive in the rural areas and that the interesting standards work now resides in CogNea. Cognea contributed to the standard through ECMA for interference-avoidance mechanisms.

In addition to the usual challenges of creating a standard and driving adoption, the consortium must also wrestle with limited spectrum. While there are available channels in the "whitespaces" left by the move of the TV channels, there's still a limited number of slots. You can use this site called ShowMyWhiteSpaces to locate the open channels in your zip code.

Best regards,

Hall T.

SDR Applications--Solving the Interference Issue

2009-12-11T06:56:00.001-06:00

There's a saying in business--find the customer pain and then solve it. While it may be oversimplifying the case for building a business it's not a bad place to start. In the world of Software Defined Radio the corollary is find the interference and then solve it.

Solving interference in the wireless network seems to be one of the over arching themes for SDR companies today. If a technology can solve an interference issue, then there's a definite business opportunity for that technology. Governments around the world are trying to unify their networks to work with other countries and enable inter communications. This is another pain point that SDR could potentially solve.

Other applications include:

Ability to access spectrum during time of emergency.

Interfacing with non-public safety systems. The Minnesota bridge collapse is one example. Bystanders of that disaster could provide photos back to the public safety groups through the use of their cell phones giving first responders additional information.

-- Implementing lower cost broadband service in rural areas with little or no wireless infrastructure. Using SDR to reuse existing networks.

-- Expanding coverage indoors in large buildings through femtocells.

-- Managed access systems for prisons. These can capture cellphone calls and allow only legitimate calls to go through.

-- Assisting in harmonizing the regulatory treatment of satellite signals in countries around the world.

-- Providing backhaul for the satellite industry through broadband and mitigating wireless interference from Wimax systems.

These are just a few of the applications that SDR proponents hope to accomplish.

Best regards,

Hall T.

The SDR Forum -- December 2010 Conference

2009-12-03T15:43:00.001-06:00

The SDR Forum promotes the success of the next generation radio technologies with members from commercial, military, and academic circles. The group boasts of a 100+ members. The conference this year was held in Washington DC and grew in attendance to over 500 which is a 20% rise of last year and is remarkable given how most conferences shrank in size.

DannyWeitzman of NTIA gave one of the keynote addresses. In his talk he compared the innovation of the internet in the 1990s to the current state of the spectrum today. The internet was

--easy to add technologies

--cost of failure is low

--done without lawyers, in particular regulatory lawyers.

In an effort to foster the development and adoption of software defined radio tools and technologies he asked what would be helpful and proposed testbeds and structured testing environments. He noted that the internet was itself a platform for testing

The NTIA doesn't hear from the public enough and then threw open the floor for feedback. The resounding answer from the audience to his question was "money." There needs to be an investment of money into the industry to drive development further and faster.

Weitzman noted that the commercial success of the internet happened on the edges and while it was government sponsored in the basic infrastructure, the commercialization was driven less by government and more by the industry players.

Other members of the audience talked about the need for gauging sensitivity of current systems to noisy environments. As the specrum changes, can more users fit into the spectrum without disrupting existing systems? and can we improve those existing systems?

Another comment was the ability to transmit without a license if you're sure you won't interfere with the spectrum. This would speed up development time dramatically. Ironically, there was no wireless service in the keynote room. Why couldn't the engineers use that space without a license to test out their designs?

Best regards,

Hall T.

4G -- Next Wireless Technology Standard

2009-11-20T06:43:00.004-06:00

The next major wireless standard on the horizon is 4G with the promise of bringing 100 Mbps and connection speeds up to 50 times faster than 3G networks. Quality of Service (QoS) will be greatly improved in spite of new technical hurdles. In this article the author shows that one of the main benefits is location-based applications. I've heard of applications under development in which one can point a cell phone camera at a store front and through the use of location-based tracking and image processing, the system can tell you more about that store -- specials, operating hours, etc. The location-based market is probably one of the fastest growing markets in the wireless world today. 4G will enable more sophisticated rollouts.

Best regards,
Hall T.

4G -- Next Wireless Technology Standard

2009-11-20T06:43:00.001-06:00

Open Base Station project

2009-11-13T06:48:00.000-06:00

The Open Base Station Project is an open-source Unix application that uses the Universal Software Radio Peripheral (USRP) to present a GSM air interface to a standard GSM handset. This project seeks to provide mobile wireless communication for about 1/10 the cost of a commercially available option. The tools are such that graduate students can build their own GSM networks as seen in this blog post. According to their project blog they've made substantial progress in field testing it at Burning Man.

Best regards,
Hall T.

802.22 Standard -- Working Group on Wireless Regional Area Networks ("WRANs")

2009-11-06T08:25:00.001-06:00

The goal of the IEEE 802.22 Working Group is to develop a standard for a cognitive radio-based interface for use by license-exempt devices which must operate on a non-interfering basis with other devices in the frequency spectrum that is allocated to the TV Broadcast Service. The standards developed so far are available for download here. It is interesting to note that the FCC and the IEEE plan to managing the white space channels through a centralized clearinghouse approach. You can read more here about the structure.

Best regards,

Hall T.