March 2009

Emergence of Software Defined Radio, SDR

HomeToys eMagazine Article - Emergence of Software Defined Radio, SDRAuthor: Pala Trinadh

This article presents a new approach called Software Defined Radio (SDR) for implementing communication systems. Various issues and challenges faced by the present communication systems design and how the Software defined Radio approach addresses these issues and how it benefits the communication industry and users are discussed in detail. The Technologies, Market, Industry support factors that are driving the SDR approach are narrated. The architecture and the components that make up the SDR are explained and illustrated for the purpose of understanding the technology. And also, the hardware and software components required to build a practical SDR are investigated. The recent availability of multi processors, FPGA, software reference models, and developmental tools that are accelerating the penetration of SDR into the cellular market are explained and reviewed. Currently available SDR reference systems and their modular and extensible architecture are also presented for sake of designers. The market trends and predictions for the SDR are discussed. The paper concludes by defining the future SDR capabilities and identifying the opportunities that exist for IP, Design services business

Introduction

The concept of Software Defined Radio has been around in the field of military for sometime now. Now, with the rapid advances in DSP processor, FPGAs,  multi core and parallel processors, and due to the fast time to market requirements, it is emerging as an important commercial technology. SDR is already mature enough to provide high quality voice communication for amateur radio systems without exceeding the Single Side Band (SSB) and without expensive broadcast studio equipments.  Presently, there are companies like Intel who target the SDR based products market with their single chip solutions that support Wifi, WiMax, and DVB-H digital TV. FCC is also supporting SDR by including time—in addition to frequency and power—when deciding how radio bandwidth is used. Software-defined radios on the drawing boards today could use these rule changes, and ever-increasing processor capability, to combine the functions of pagers and mobile and cordless phones into a single device. These devices can operate around the world by adapting to each country's regulatory idiosyncrasies on the fly.

Issues in Present Communication Systems.

Lack of  Compatibility

Current scenario in the market is that a single user can own several communication devices, such as  Cell phone, Cordless phone, wireless Internet gadget, pager, GPS tracker, scanner, car phones, wireless intercoms, ham radios, Citizens Band radios, family radios, and more. For every one of these devices, a separate license to be obtained from FCC. Each device is designated to communicate on a specific frequency band provided by FCC. And also the frequency range allowed for cell phone communications in one country may overlap the frequency range regulated for emergency services in another country. This lack of compatibility between different types of devices and different communications and network infrastructures is an issue in the present communication systems. Software defined Radio would be able to solve these incompatibility problems and many other issues in the present Communication Systems.

Not able to Quickly Upgrade to new standards

The legacy handsets currently in the market can not be easily upgraded to the new communication protocol standards like 2.5G, 3G and 4G. Most of the equipments are not even compatible to new standards. It requires redesign and re-development of the hardware and the associated software. With the current architecture of proprietary custom hardware of the legacy handsets, it is next to impossible to upgrade to new standards quickly.

Lack of Spectrum  and growing users

The growing number of users of mobile phones is putting a huge strain on the existing bandwidth and communication infrastructure.  With more and more users requiring access to different types of spectrum, this problem can only grow. Today's hardwired radios cannot resolve these issues. However, solutions can be found in software

Emergence of SDR

Presently, people have many different communication systems suited for different demands at their disposal:

  • Personal Area Networks (PANs) like Bluetooth for short distances
  • Wireless Local Area Networks (WLANs) like IEEE 802.11a/b/g/n for internet access,
  • Cellular systems of second and third generation like the Global System for Mobile Communication (GSM) or the Universal Mobile telecommunication System (UMTS).
  • All the systems mentioned above have been developed for different applications and transmission situations (channels). These Communication systems have different needs
  • The frequencies used range from 800 to 5800 MHz,
  • FEC using Reed-Solomon, block, convolution or turbo coding
  • Modulation using Quadrature Phase Shift Keying (QPSK), Gaussian Minimum Shift Keying (GMSK) or even Orthogonal Frequency Division Multiplexing (OFDM) and Frequency Hopping (FH).

The handset that works for one communication system may not work for another communication system. So subscriber has to have multiple handsets to communicate over different communication system. However, with the SDR solution, a single handset can be made to work with all the communication systems.

Software Defined Radio

Definition of Software Defined Radio

  • The communications systems created using the Software Defined Radio concept can handle multiple frequency bands, understand multiple transmission protocols, be reconfigured on the fly, and be easily upgraded—all in a single device design.
  • A Software Defined Radio (SDR) system is a radio communication system which can potentially tune to any frequency band and receive any modulation across a large frequency spectrum by means of as little hardware as possible and processing the signals through software

SDR A Transmitter & Receiver perspective

  • A software defined radio, on the receiver side, employs a wideband Analog to Digital Converter (ADC) that captures all of the channels. The receiver then extracts down-converts and demodulates the channel waveform using software on a general purpose processor."
  • On the receive side, the idea is to get a wide band ADC as close to the antenna as is convenient, get the samples into something we can program, and then grind on them in software.
  • "A software radio is a radio, on the transmitter side, defines all the channel modulation waveforms in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband DAC and then possibly up-converted from IF to RF.

Advantages of  SDR

SDR Multiple  benefits

  • SDR provides a Standard architecture for a wide range of communications products.
  • By extending the capabilities of current and emerging commercial air-interface standards,   Non-restrictive wireless roaming is possible for consumers.
  • SDR enables building products that support Uniform communication across commercial, civil, federal and military organizations.
  • The communication systems can be more flexible and adaptable that has potential for significant life-cycle cost reductions.
  • With the most of the functions in the system implemented in software, it is possible to have over the air downloads of new features and services as well as software patches. These advanced networking capabilities allow truly "portable" networks

Worldwide interest and investment in the SDR technologies is growing significantly, with key standardization and development efforts now taking place throughout Europe, North America, Japan, Korea, and China. In addition to the broad benefits listed above, SDR technologies offer unique benefits to players on every tier of the value chain.

SDR Based Personal networks

  • The Personal Area Network (PAN) is based on the trends towards increasing connectivity of personal information and communications devices. There is proliferation of wireless devices and cell phones, pagers, wireless PDAs, and so forth. This is forcing many consumers to carry multiple, self-contained radio devices on their body. Each device has its own receiver and transmitter, its own signal processing circuitry, and each requires a battery large enough to operate a wide area network transceiver.
  • If SDR-based PAN architecture is adopted, individuals would enjoy greater connectivity among their various information and communications devices. Also, those information and communications devices could be produced in smaller, lighter, more convenient form-factors.

Technologies behind SDR

Technologies Driving SDR

Currently, there are several technologies that are sufficiently advanced to make the SDR feasible.

  • There are Field-programmable gate arrays (FPGAs) with capability to support multi million gates also with integrated processors and other DSP specific modules like MAC (Multiplier And Accumulator) inbuilt.
  • There are also dedicated custom built Powerful, cost-effective programmable digital signal processors (DSPs).
  • Recently, some companies have come up with Massive array processors on a single chip, which is very much suited for Signal processing applications and to support multiple protocols.
  • The critical front end components in the RF communication systems, like ADCs and DACs are available with high performance in terms of wide bandwidth and accuracy and response time.
  • Development of ultra-fast standardized data-transfer interfaces for data routing among multiprocessors.
  • Availability of Various real-time Operating systems and initiative by JTRS program, a specification for Software Communications Architecture (SCA) are driving the SDR technologies.

Challenges faced by SDR

On the other side, there are some challenges that are still being addressed to make the SDR more successful in military, commercial and civil applications. .
         

  • One of the most basic issues is that the tools and network infrastructure must be in place before SDR products can become effective, reconfigurable and agile devices in a widespread marketplace.
  • Security of downloads. For example, given a script that describes a link-layer protocol, there must be a phase in which the protocol is downloaded to the hardware and run as a configurable protocol. Such downloads must be signed and have digital authorization. Otherwise, downloads might be made to devices that could then broadcast on unauthorized bands. Security issues facing SDR technology include encryption, user identification, device authentication, and others.

Components in SDR

Typical Communication System

A typical Communication system, as shown in Figure 1, consists of Source coding, Channel coding, Digital Down sampling, up sampling units along with the RF front end along with Antenna. Most of the RF front is design using Hardware components specific to the communication system.  Present communications systems have specific ASICs for implementing the base band Modulations schemes, FEC schemes and other Source coding chips like MPEG2/MPEG4.  Up-sampling and Down-sampling filters are also implemented using custom ASICs or FPGAs.


Figure 1: Typical Communication System

Ideal SDR concept

  • In the case of a RF communication receiver, the ideal scheme would be to attach an analog to digital converter (ADC) to an antenna. This digital data would be read by a digital signal processor, and then its software would transform the stream of data from the converter to any other form the application requires.
  • Similarly, an ideal transmitter would have a digital signal processor that would generate a stream of numbers defining the transmission waveform, that would be sent to a digital to analog converter (DAC) connected to a radio antenna.

The ideal scheme is, due to the actual technology progress limits, not completely realizable. Refer to the below Figure 2 for illustration of the ideal SDR.


Figure 2: Ideal SDR Transmitter and Receiver

A Practical SDR

  • For frequencies below 40Mhz, Actual software radios, use “direct conversion” hardware solution. Wherein an analog to digital converter (ADC) is connected quasi directly to the antenna (some preamplifier and impedance adapting circuitry is present to have the input of the ADC correctly matched to the antenna). The output stream of digital data obtained by the ADC is then drawn to the software defined processing stages.
  • For frequencies above 40MHz, the actual ADCs doesn't perform sufficient speed so direct-conversion is not possible and  hence a superheterodyne RF front end architecture is adopted, to lower the frequency of the received signals to intermediate frequency values (IF) under the actual 40MHz convertible limit. This IF is then treated by the ADC.
  • Just to extract a narrow band of interest, it is not advisable to directly handle high bandwidth signal in software, thus the SDR does not directly interface to the ADC/DAC, but preceded by Front-end processing units to down-convert, up-convert the signal.
  • A good software radio must operate at any sample rate within a wide range of rates, in order to be compatible with many protocols; hence an adaptive control is crucial. It can be implemented either with a hardware link to the converter, or in software.
  • Any signals above the sampling frequency would "interfere" with the sampling, causing spurious signals to appear in the data stream at a frequency that's the difference between the signal and the sampling frequency. For this reason, a low-pass analog electronic filter must precede the digital conversion step.
  • Real analog-to-digital converters lack the discrimination to pick up sub-microvolt, nanowatt radio signals. Therefore a low-noise amplifier must precede the conversion step - including this device introduces its own problems e.g. if spurious signals are present (which is typical), these compete with the desired signals for the amplifier's power. They introduce distortion in the desired signals, or may block them completely. The standard solution is to put a filter between the antenna and the amplifier.

The RF front End modules are illustrated in the Figure 3.

Figure 3: Practical SDR RF Front End

A Typical SDR Architecture

A typical SDR system is shown in Figure 4

     

 

Figure 4: Typical SDR Receiver system

  • An SDR is designed to receive multiple RF carriers, with 15-20 MHz typical bandwidths, using one or more air standards.
  • These carriers pass through a band-select filter, which reject blockers and interferers from adjacent frequency bands.
  • A low-noise amplifier (LNA) follows, providing gain to the incoming signals. The analog RF mixer then down converts the desired signal to a convenient intermediate frequency (IF) for digitization.
  • The down convert is followed by an integrated IF to base band receiver subsystem.
  • for example, incorporates a high performance 14-bit, 92-MSPS ADC to digitize the IF spectrum, and a four-channel digital down converter (DDC) that tunes and filters the desired signal.
  • The output of the DDC consists of a channel-filtered digital IF signal, which is then demodulated by a TigerSharc DSP.
  • With this architecture, the DDC and DSP can easily be reprogrammed to adapt to new cellular standards or changes in frequency spectrum allocation.

SDR Test System

Traditionally, a separate stand-alone instrument would be needed for every communications standard to be tested. Each instrument has vendor-defined functionality for a particular standard. The communications measurement algorithms for the standards exist as firmware running on the embedded processor in each instrument, which means they are not user-accessible or customizable. Purchasing a new stand-alone instrument for each standard that you need to test is not productive or cost-effective. This is pushing engineers to seek flexible, out-of-the-box solutions.
Flexible Software-Defined Communications Test is the way to keep stride with wireless and communications advances. One can take a software-defined approach to instrumentation by using coding and modulation software to generate and measure signals through modular, general-purpose RF instrumentation. This software-defined radio (SDR) approach to test is completely application-driven and user-defined. One can use it to leverage the software modeling and simulation software used in research and design for test and measurement. The Department of Defense (DoD) already supports this strategy

SDR IN TACTICAL NETWORKS

Joint Tactial Radio System (JTRS)

  • As a technology, SDR is quickly becoming established. It is being increasingly embraced in the wireless defense market. In North America, this move is driven by JTRS.
  • The functionality and expandability of the Joint Tactical Radio System is built upon the Software Communications Architecture (SCA). The SCA is an open architecture framework that tells designers how elements of hardware and software are to operate in harmony within the JTRS. It governs the structure and operation of the JTRS, enabling programmable radios to load waveforms, run applications, and be networked into an integrated system
  • The Software Communications Architecture (SCA) defines standard interfaces that allow waveform applications to run on multiple hardware sets. The SCA defines a Core Framework (providing a standard operating environment) that must be implemented on every JTR set. Interoperability among radio sets is enhanced because the same waveform software can be easily ported to all JTR sets

SDR in Tactical Networks

Figure 5: Tactical Network of War Tanks

Wide variety of Radio networks are in different services.  It could be a RF network for Tanks in the war field, as illustrated in Figure 5, or commercial Taxis in cities. The important characteristics of Radio link are Mobility and Networking. Radio links uses different radio frequencies, different modulation techniques, different information coding formats and protocols. But basic operations in the RF network are Control and Information processing.

SDR Forum Software Reference Model

  • Multiple processing elements operating in parallel to implement the two paths , control and information processing, are shown in Figure 6
  • One path is for control, directives to individual system components needed to execute system operations such as increase volume, change frequency, switch antennas, or switch to a different air interface.
  • The other path describes the flow of information carried by the radio signal. It contains three elements.
  • For the receive function, the RF processing required to demodulate the incoming signal and change it into a digital representation of the information.
  • The security module may be null, or it may be operating complex cryptographic algorithms.

Figure 6: Control & Information flow in Mobile Networks

  •  Information processing and I/O is the same work performed in conventional computers to operate as a network element, interface to a telephone network, provide audio for a handset, or interface with local peripherals such as disks and printers.

SDR Multiprocessor Reference Model

  • As shown in the Figure 7, each processing element in a multiprocessor SDR has its own set of software modules to implement the two parallel paths
  • The set for each processor has a layered structure, with hardware at the bottom, processor-specific software in the middle, and software modules that implement the application on the top.
  • The application modules contain all of the processing capability to implement the radio's control and information functionality. This leads to the fundamental benefit of a software defined radio:
  • The attributes of the system can be changed by bringing in new application software without any change, replacement, or modification of hardware.
  • The underlying middleware remains in place to load, unload, and support the application software.


Figure 7: SDR Multiprocessor reference model

SDR SYSTEMS

  • A detailed representation of a high-density, commercial-off-the-shelf (COTS), heterogeneous software-defined-radio (SDR) platform from Spectrum Signal processing is shown in Figure 8
  • The boards also house processors that support the use of a POSIX-compliant RTOS. The SCA (Software communication Architecture) software stack can be supported. SDR- 3000 platforms can then be used for JTRS radio implementations.

Pro-3100 System

  • It is a CompactPCI FPGA-based processing engine. It possesses four user-programmable, Xilinx Virtex-II FPGAs for the processing of high data rates. In a typical SDR system, this can accomplish the multi-channel DDC and DUC functions
  • High-performance buses based on industry standards, such as Ethernet and Serial RapidIO, provide the high data throughput (320 Mbps)
  • An embedded PowerPC controller is present to host control software for the board resources.

Figure 8: SDR platform from Spectrum Signal processing 

PRO-3500 System

  • It is a PowerPC MPC7410-based CompactPCI board.
  • It operates as a baseband-processing engine and has two embedded PowerPCs. It can support further processors by adding modules to two ePMC sites that support quicComm links.
  • The high-bandwidth combination of flexFabric and quicComm provide the high data I/O rates required to meet the processing capabilities of the PowerPCs.
  • The flexFabric is Serial RapidIO-based for a point-to-point connection between PRO-3x00 boards at up to 320 Mbps

 

Figure 9: Quad IF Receiver; Single IF Transmitter

By using this Pro system blades (Pro-3100, Pro-3500), one can configure communication systems supporting number of carrier channels. This is illustrated in the Figure 9.

Hardware for SDR

Industry Directions

  • Many companies already have commercial products running different SDR radio communication protocols and standards. Companies that are working on SDR solutions include Intel, Morphics Technology, Chameleon, Vanu Inc., and Raytheon, among many others.
  • There is also significant academic research going on in SDR areas. Researchers are exploring new energy-efficient algorithms, reconfigurable architectures based on ASICs (application-specific integrated circuits), digital signal processing for SDRs, and the use of FPGAs (field-programmable gate arrays) for SDR silicon.
  • In addition, Intel is working with United States, European, and some Asian regulatory authorities to adapt regulatory guidelines for agile radio technology.

Highly flexible Processors

Processors from Chameleon systems

  • Chameleon's first generation reconfigurable communication processor (RCP) provided a solution for processing-intensive multi-channel communications applications and was geared towards the 3G wireless base station market. The company’s platform-based approach, combined with a microprocessor-style debugging environment, enabled customers to implement proprietary algorithms and achieve fast time-to-market.
  • This first generation product was well received by major wireless base station manufacturers, including Ericsson, Nortel, Motorola, Alcatel, LG, Fujitsu
  • Chameleon’s streaming data processing (SDP) approach provides a cost effective and easy-to-use solution for data-intensive DSP applications, enabling DSP designers to rapidly optimize their own system, application and algorithm designs directly onto a fast, parallel implementation suitable for product delivery.

Processors from MorphICs (Infineon)

  • MorphICs is a privately held fabless semiconductor company acquired by Infineon. It is an innovative developer of configurable digital base band circuits for terminal devices and base stations for 3rd-generation (3G) wireless communications.
  • MorphICs’ core technology permits extremely efficient implementation of programmable multi-standard platforms for 3G/WLAN systems. The company is currently sampling its base station signal processor product, which is entering trials in commercial networks, and is developing technology that enables efficient multi-network operation of terminals.

Processors from picoChip

  • World-class multi-core: picoChip is the leader in multi-core DSP, with production silicon delivering dramatically better performance-per-dollar than legacy processors or FPGAs. The incredible performance makes software defined radio and next-generation wireless an affordable reality.
  • The picoArray is a massively parallel, Multiple Instruction Multiple Data (MIMD) architecture composed of processing elements of various types linked together by the patented picoBus interconnect. There are two types of processing element — 16-bit Harvard architecture processors each with 3-way LIW and local memory and hardware co-processors to accelerate specific functions.
  • WiMAX: picoChip is the industry-standard for WiMAX chipsets, with more presence in the WiMAX Forum Plugfest than any other architecture. Delivering upgradeable platforms from 16d to 16e, Wave 2 MIMO and beyond, with complete reference designs that are interoperable and certified

SDR Developmental tools

TI  Reference platform

  • Texas Instruments Inc. (TI) has Small Form Factor Software Defined Radio (SDR) Development Platform, said to be the industry's first and only development platform targeted at the portable military communications market.
  • The platform provides the entire signal chain hardware from antenna to baseband as well as a software board support package that supports a complete suite of software development tools in a single integrated development platform.
  • With this kit, Developers can easily design waveforms as well as create and test single or multi-protocol radios for applications in military, public safety, commercial, professional mobile radio (PMR) and land mobile radio (LMR) communication systems as well as RFID readers.
  • Additionally, as the platform is integrated to work with Simulink model-based design tool, developers have the option to use C/HDL or MATLAB Simulink to quickly test proof-of-concept designs and then optimize the architecture for cost and power.
  • The Small Form Factor Software Defined Radio Development Platform kit includes free evaluation copies of TI, Xilinx and GreenHills software and tools. An Enhanced SCA version of the SDR Development Platform including licensed copies of the complete software suite including SCA framework and ORB middleware is offered directly by Lyrtech

Lyrtech DSP/FPGA developmental products

  • The Small Form Factor (SFF) Software-defined Radio (SDR) Development Platform is a unique Lyrtech new product that addresses the special portable SDR needs of military, public safety, and commercial markets.
  • Lyrtech provide a limited feature version of the SFF SDR Development Platform for digital processing and also full version that supports CORBA-enabled FPGA SCA Platform. The platform is shown in Figure 10.
  • Lyrtech offers SDR turnkey solutions with FPGA-based IF processing (for agile down sampling and frequency translation) and DSP-based base band processing (to enable the use of mainstream C-based DSP software) -- all programmed from within the Simulink system-level environment in real-time

Figure 10: Lyrtech SDR developmental platform

IMEC  Referenece design

  • IMEC’s has SDR reference design that addresses the communication industry demands that include low power, low cost and a short turnaround time for a final product. The research house also built in flexibility to be able to pull in signals across a wide spectrum that includes everything from data to radio signals.
  • At the high end of the spectrum, the design will receive signals from 100MHz to 600MHz, with the capability of extending that all the way up to 10GHz. In addition, it supports signals from 40MHz to 500MHz.

DSP Tools Inc Project

  • The SDR-4000 board is a flexible platform for implementing high performance 'software defined radio' circuitry in a powerful Field Programmable Gate Array (FPGA).  It can be connected via a high-speed USB 2.0. as shown in Figure
  • The SDR-4000 contains a 14-bit A/D converter, sampling at 125MSps. All samples are fed to the SDR FPGA where the radio functions are performed. Complete user control via USB endpoints is available for radio and down-converter functions within the FPGA.
  • The FPGA in this SDR reference platform accommodates, A/D signal strength monitor for automatically controlling VGA Gain, two independent Digital Down Converters ( each containing its own Direct Digital Synthesizer) Complex Mixer, and Programmable Digital Filters And the FPGA also accommodates Beat Frequency Oscillator for Signal Sideband and CW, Snapshot Capture memory,  Digital filters which are loaded from the PC over the USB so their bandwidth and selectivity can be easily changed, Automatic Gain Control, Demodulators for AM, Single Sideband and FM

Figure 11: SDR-4000 reference platform

Matlab Flow for SDR

Figure 12 illustrates the Matlab based Hardware Implementation Flow for SDR

  • MathWorks:  MATLAB, Simulink & Real Time Workshop  will be used for Modeling & Simulation and  C Code Generation for TI DSPs
  • Xilinx:  System Generator & ISE will be used for Optimized HDL for Virtex & Spartan FPGA families. The Xilinx ISE will be used for Synthesis, Place, & Route
  • Texas Instruments:  Code Composer Studio is Development environment for TI DSPs
  • Lyrtech Signal Processing Development board will have  Xilinx FPGA and TI DSP.
  • Refer to the Figure 12 for  illustration of how the Mathworks, Xilinx, TI products will be used for SDR development.

Figure 12: Matlab flow for SDR implementation

SDR Market

Market drivers

Presently, the U.S military is driving the SDR market by building SDR based communication systems for its military applications. JTRS accounts for most U.S. purchases of SDR technology. Recent DoD contracts under the JTRS program are also expected to help smaller SDR vendors while stimulating the market for new products and technologies. Researchers at Virginia Tech have developed a software framework that could serve as the foundation for future military radios. The Software Communication Architecture (SCA) is also being considered as the missing link for boosting the commercial SDR market.

SDR Sub-modules Market

Some segments of the wireless device industry stand to benefit from SDR technologies, while others may see their margins and market share shrink.

  • ADC and DAC manufacturers, Programmable logic and processor vendors RF MEMS fabricators, in particular, are most likely to gain market share and margins with the adoption of SDR.
  • Discrete component manufacturers are likely to see shrinking market share.
  • Ironically, software developers, while at the core of the SDR revolution, may find it difficult to reap profits from the switch to flexible, software-based radio architectures.

SDR Secondary Market for Spectrum

As the SDR based products can emulate any communication radio capabilities, by simply replacing software, there is good potential for secondary market for spectrum.

  • For longer-term leases of the spectrum, the licensor would have the opportunity to recover the cost of the necessary equipment.
  • With shorter-term leases, however, the licensor may not be able recover the cost of such specialized equipment -- or even interest a manufacturer in producing it.
  • That is where the SDR technology could play a major role by reducing the cost (and time) of deploying radio equipment on temporarily under-utilized spectrum. By providing the needed flexibility in equipment, SDR can help enable secondary market applications.

Multi Carrier SDR Market

  • SDR design is based on Multi RF Carriers support by a single platform.
  • Single RF carrier designs have matured and the component costs associated have reduced. For example, 2G/2.5G markets.
  • High performance RF components (ADC, LNA, etc, Band pass Filters, etc) are required to meet the SDR requirement of multi-carrier support.
  • The Cost Advantage of SDR comes with the ability of this system to support multiple carriers without additional components compared to single RF carrier systems.
  • As the SDR is designed to support multiple carriers, the cost per carrier would reduce as more carriers are added.
  • The current cost of components puts this threshold to 4 to 6 carriers for SDR.
  • SDR is more suitable for markets with large population and higher demand for Capacity.

Cognitive Radio

  • In the future of SDR technology, a cognitive radio will be able to sense its surroundings and the presence of other signals. Using that information, it will then be able to adapt, without user intervention, to its user's communication needs. Essentially, cognitive radios will be able to create their own adaptable, on-the-fly wireless networks, based on the needs of the user at that moment.
  • One of the biggest advantages of SDR technology may be giving radios the ability to make use of frequencies that are not currently in use. Right now, at any given time, only a small portion of the radio spectrum is in active use. SDR technology may allow a cognitive radio to determine an unused frequency in what is currently an unlicensed spectrum, and then shift to that frequency for communications. This may make it easier to manage the overall radio spectrum, and even avoid the need for some types of FCC licensing.

Opportunities for IP & Services Companies

IP & Design service companies can develop various SDR components as IP cores targeted to FGPA/DSP devices. They also can involve in various design services activities around SDR reference platforms, algorithm development, porting & testing of the SDR software to Cellular handsets, and base station communications platforms. Some of the opportunities are listed below.

  • Development of reusable components such as DDC, DUC,  Digital FIR Filters, Poly-phase filters, Modulators and De-Modulators for various communication standards, MAC (Media Access Control) Layer and protocol layers, Components for FEC,  RF Analog Front End as IP
  • SDR software based on SCA, Generic Reference platform for SDR using latest chipsets (processors/DSP), Development of SDR base-station/mobile prototype products
  • Cognitive radio algorithms for wireless networks, Encryption and security aspects of SDR systems, Design services around SDR, Test Systems
  • Design services like SDR software porting and testing for SDR products, Taking part in SDR forum’s activities and identify the development areas.

Acknowledgment

I would like to thank DSP/MM Group Head Mr. Madhu Parthasarathy for introducing me to SDR and providing an opportunity to explore this interesting subject.

References

http://www.Hpsdr.org  - High performance software defined radio
http://www.sdrform.org - The official SDR Forum Web site offers information into ongoing work on SDR technology, research activities, joint developments, and new products
http://www.globalsecurity.org/military/systems/ground/jtrs_sca.htm
http://www.lyrtech.com/  - Lyrtech Lyrtech is a leading ODM that delivers advanced digital signal processing solutions to top-tier partners such as Texas Instruments and Xilinx, as well as numerous international customers.
http://www.ti.com -  Leader in Analog Technologies, Semiconductors and Digital signal processing.
 http://www.imec.be -IMEC, Europe's leading independent nanoelectronics and nanotechnology research institute
http://dsptools.com -is an engineering company specializing in development of DSP-based hardware and software
http://www.chameleonsystems.com - a fabless semiconductor company, develops, markets, implements and supports a high performance streaming data processing platform for digital signal processing (DSP) applications
http://www.picochip.com/ - is dedicated to providing fast, flexible wireless solutions for next generation telecommunications systems.
http://www.spectrumsingal.com – develops SDR systems
http://www.xilinx.com/ - Xilinx is the leader in the digital programmable logic device (PLD) market.
http://www.mathworks.com - is the world‘s leading developer of technical computing software for engineers and scientists in industry
http://www.wikipedia.org/ - The biggest multilingual free-content encyclopedia on the Internet

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