The paper will discuss Information Assurance (IA) issues, including security concerns and related countermeasures, for small form-factor Software Defined Radio (SDR) systems. The purpose is to highlight potential privacy and security vulnerabilities and to offer strategies for overcoming these to make the systems and component devices appropriately secure. An example Active RFID (aRFID) system is described that provides high granularity logistics tracking, monitoring, and geo-fencing capabilities in RFIDinfrastructure-denied environments to meet the military services requirement for logistics visibility and control to "the last tactical mile." This paper emphasizes the need to design each component with multi-layer IA and quality assurance in mind so that vulnerabilities are addressed at the root level. This is important in light of the fact that nefarious groups start "attacking" the systems before they are even fielded.
This paper explores the use of self-organizing maps as a mechanism for performing unsupervised learning for signal classification. Approaches using unsupervised learning have a key advantage over traditional approaches that utilize neural networks and support vector machines because they do not require a training phase. We develop signal classifiers using self-organizing maps and explore their robustness. Another concern with using unsupervised learning is the ability for an adversary to shape what is learned. In this paper we explore avenues for attack, and how they affect the performance of the signal classier. This paper extends previous work on this topic by building a full signal classier and quantitatively measuring its performance, and introducing two new types of attacks against classification engines.
The feature to be reconfigurable over the air interface is one of the main advantages of the SDR systems that offer operational benefit and considerable promises, but at the same time, introduces several important security issues like regulatory aspects, protection of contents, intellectual rights, and assurance of unaltered and appropriate software load. These aspects highlight that one of the main challenges in this field is the security of radio software download. The aim of this paper is to address the problem of secure radio software download in SDR devices, identifying existing solutions, comparison with regulations, and define a policybased mechanism to secure download reconfiguration files into SDR devices according to regulations, needs of the service providers and users.
In 2004, 2005 and 2006, the authors provided details of wireless network threats discovered during wireless threat analysis studies exposing a potentially serious flaw in the security architecture of software defined radio (SDR), cognitive radios (CR) and wireless mobile platforms. The reconfigurable radio terminal, and the host to which it is attached, are potentially vulnerable to exploitation, malicious reconfiguration and denial of service as a result of Internet based attacks delivered via a wireless signal. These vulnerabilities extend to consumer mobile computing devices with embedded wireless network interfaces including WIFI enabled laptops, PDAs, Smart Phones and Cognitive Radios. In January 2005, the Joint Tactical Radio System (JTRS) issued Change Proposal CP295, "Exposed Black Side" to address this new class of threats to SDRs (Figure 1). The Software Defined Radio Forum also considered these threats in security related Recommendations published in 2006. This vulnerability was realized in November 2006 with the "Broadcom Exploit" attack affecting world-wide consumer WIFI installations including those from Apple, Gateway, HP, Dell and eMachines. This paper presents an architectural approached called High Assurance Wireless Computing System (HAWCS®) as one way to address such concerns. HAWCS® leverages state of the art separation kernel technology, originally developed for Multiple Independent Levels of Security (MILS) applications, to fortify user end-node integrity and isolate "soft" operating system kernels and applications from network threats such as root kits without the need of additional hardware. HAWCS® addresses CP295 related security flaws in SDR and wireless mobile devices without the need for costly encryption hardware, allowing for greater assurance in mobile eCommerce and endpoint computing.
Divi Gupta; Dev V Gupta; Patrick A Kelly - University of Massachusetts; Zhiguo Lai; Abbie Mathew - NewLANS, Inc.
Wideband RF front end is susceptible to narrowband interferers that can impair the performance of the receiver. Currently there are no tunable filters that can be swept across bandwidths greater than 1 GHz. The paper proposes an innovative state variable filter which can be placed at the receiver front end covering frequency up to 10 GHz. The technology enables developing multiple filters which can be independently applied to the bands of operation. Alternatively, they can be brought in close proximity to each other in order to change the filtering characteristic. The state variable wideband tunable filter is digitally controlled by an eternal micro-controller or DSP.
Existing Anti-Jam (AJ) and interference mitigation techniques are based on the assumption that the nature of interference is known a priori. Generally, one or more fixed AJ techniques (FATS) are applied to reduce the impact of the jammer or interferer to a receiver. A more general approach is to apply cognitive radio technology, whereby the receiver's AJ processing and receiver signal processing adapt to the incoming interference environment by determining the characteristics of the interference, then jointly optimizing signal processing to mitigate the characterized jammer or interferer. We refer to this approach as a Cognitive AJ Radio System (CARS). The CARS architecture consists of three primary components: a signal analysis block that estimates the characteristics of the signal and jammer, an interference mitigation algorithm that adapts its AJ processing to the measured jammer characteristics, and a receiver signal processing block that adapts to the measured signal and jammer characteristics. This paper compares the performance of a representative CARS architecture to that of a FATS architecture when applied to a direct-sequence spread spectrum (DSSS) receiver. The bit error rate (BER) performance of CARS and FATS under the influence of various types of jammers is evaluated by simulation. Simulation results show that the CARS approach allows data demodulation to be reliably performed even in severe jamming conditions, whereas FATS approaches fail to achieve such performance levels.
In 2007 we reported a flexible integrated circuit transceiver operating from 100 MHz to 2.5 GHz with continuous coverage over that range [1-2]. A new version of the chip is now available with improved performance and significant new features. Notable performance improvements include operation up to 4 GHz using the on-chip direct digital synthesizers (DDS) and up to 6 GHz using an external LO source. Noise figure, phase noise, linearity, and Tx output power are much improved in the 2-4 GHz range. The most significant new features are on-chip data converters and a high speed digital interface based on the digRF standard. The new chip is 5.0 x 5.4 mm in 90 nm CMOS and is housed in a 10 x 10 mm 132-pin dual row MLF package. The system development kit includes GUI programming software and an evaluation board with a Virtex5 FPGA and dual 1 Gb Ethernet ports.
Femtocells - small base stations deployed residentially and in the enterprise – present several challenges for RF designers. Femtocells must support the required uplink and downlink frequencies while also integrating downlink scanning capability which will be used by the network to identify neighboring femtocells and macro cells. The integration of this multi-band multi-mode functionality in a consumer electronics device presents cost and performance challenges. BitWave has developed a WCDMA femtocell reference design which supports WCDMA femtocell functionality as well as WCDMA and GSM downlink scanning using a single BitWave Softransceiver RFIC. Multi-band functionality, as implemented in BitWave's RFFE reference design, is and continues to be, extremely important to commercial radio design. BitWave will present performance data for BitWave's femtocell RFFE reference design including sensitivity, EVM and transmit mask.
Link simulator is a major tool for verifying algorithms and/or inspecting performance of implemented communication systems. As the complexity and throughput of communication system increases, reducing the operation speed is emerged as a key issue of the link simulator. In this paper, we propose a novel architecture for the link simulator which is implemented using a graphic processing unit (GPU). In our experimental tests, the GPU-based link simulator provides 64 times faster operation speed compared with conventional link simulator which uses centre processing unit (CPU) only.
In this paper, we present the agile development, implementation, and verification of an OFDM waveform PHY layer on a Software Defined Radio (SDR) development platform. The SDR platform is supported by a tailored and highly productive development system emphasizing the value of a structured development process that takes the developer through modeling, trade-off analysis, implementation, and verification. We comment on the OFDM models, the design process used to create them, their characterization and verification, and their ultimate performance characteristics. Central to the SDR platform is a massively parallel processor which is used for all signal processing, control, and data management aspects of the OFDM waveform. We present details of this computational fabric and its advantages in the implementation of OFDM waveforms and SDR applications.
The requirements for Wireless Basestations are rapidly evolving as more and more devices are becoming connected and Mobile Broadband has become a reality. Enabled by standards such as LTE and WiMax and technologies like OFDM and MIMO the throughput and capacity needs are increasing exponentially. At the same time Wireless Basestations are required to simultaneously support multiple radio standards and meet many different deployment and use case scenarios. It is becoming increasingly difficult for current solutions based on multiple application specific architectures to meet these demands while maintaining software and engineering investment Software Defined Radio (SDR) has become a key element in introducing flexibility in recent solutions, however many obstacles still remain towards a single architecture and a 100% reuse nirvana. This paper describes some of the Intel® Architecture developments and how it is becoming a practical solution towards running all Wireless Basestation workloads on the same platform. In particular we will focus on the elements that have evolved in the architecture that now allows SDR workloads to match and in many cases exceed the performance of current solutions. We provide proof points for some of the latest LTE signal processing workloads and also show how the development cost can be significantly reduced and maintained across multiple platforms and follow-on silicon generations.
The release of a variety of embedded processor platforms over the past few years has sparked an interest in developing SDRs that are capable of operating on moderate-performance hardware. Currently, the two popular SDR frameworks-the SCA and GNU Radiohave been employed almost exclusively on general purpose processors. However, to utilize one of these frameworks, embedded platforms must both maximize the efficiency of the software as well as take advantage of co-processors (such as FPGA's) to perform computationally intensive tasks. This paper presents the design and initial development of a low-cost SDR platform based around the Texas Instruments Beagleboard OMAP3 embedded processing platform along with off-the-shelf radio transceiver boards Initial performance results demonstrate basic functionality of both the FPGA interface board as well as the Beagleboard SDR engine. The platform can not only be used for embedded SDR applications, but is also valuable for low-cost SDR prototyping and experimentation.
Software-defined radio (SDR) technology has "crossed the chasm" in many market segments, including tactical radios, satellite modems and commercial wireless infrastructure. However, in order to be truly successful and reach mainstream, technology has to not only initially meet the requirements of the visionaries, but also meet the requirements of the pragmatists and conservatives – both technical as well as economic. Technologies that fail to become mainstream often do so because they fail to meet the economic requirements. SDR is a technology that has now become mainstream in many markets. By way of example, this article examines the commercial wireless infrastructure market to illustrate how SDR is meeting both the technical and economic requirements of telecommunications equipment manufacturers (TEMs) through cost reduced architectures that not only lower total cost of ownership, but also BOM (bill of materials) cost.
Have we reached the needed performance to deal with SDR (Software Defined Radio) user needs yet? Are we limited to basic applications due to conventional SDR platforms characteristics? During last years, end users' demand in communication characteristics has caused the need of advancements in SDR terminals in order to efficiently deal with high data-rate processing and innovative capabilities. Consequently, different SDR architectures have been proposed by providers and developers in order to palliate communication performance problems, mainly providing lightweight software implementations or multicore hardware replacements. However, those solutions are neither flexible enough to be integrated with conventional SDR platforms nor scalable enough to have their inner software adapted to forthcoming hardware advancements. Therefore, an adaptable multicore architecture is presented in this paper as a suitable solution to cover nowadays SDR performance needs, characterized by supporting the heaviest SDR processing and being able to be fully exploited by means of advanced parallelism techniques.
The design of radio communication systems delivering wide variety of applications with the best end-user experience through the overall wireless networks implies to develop innovative services to encompass adaptation capability requirements. Then the creation of efficient executable models becomes a mandatory step to enable system architecting of such systems under timing and power constraints. In this paper, we propose a method based on the creation of an executable model, defined at transaction level, of an adaptive multi-standard and multi-application radio communication system. A specific modeling technique is proposed to represent the behavior of the system environment for different use cases. A generic model of the system is also proposed to describe several dynamic services and the reconfiguration management functionality. Simulation results provided by the model enable to study impact of reconfiguration mechanisms.
Software-defined radio (SDR) technologies promise significant enhancements over traditional radio design in terms of waveform flexibility, reconfigurability, and modular component reuse. These benefits are typically realized through the deployment of modular software processing blocks on a variety of processing platforms, however, the processing complexity of these target platforms severely limits their capacity and, in the case of mobile radios, their battery life. Because a considerable percentage of power consumed in SDR is in baseband processing, reducing its computational load has significant implications on its power consumption, processing bandwidth, and capable throughput. This paper provides analytical analysis for modeling power consumption on SDR platforms while preserving a necessary service quality for packet radios by leveraging software flexibility. We propose using computational complexity of the softwaredefined baseband processor as a metric for comparing resource consumption on such platforms. Furthermore the paper discusses strategies for managing power consumption by adapting linklevel algorithms to reduce computational complexity, validated by hardware simulation of running a demodulator and forward error-correction decoder on an embedded processor.
Reports from DoD entities and DARPA call attention to a nationally recognized gap between current high performance computing technology and the need for quantum computing power in order to handle important national security applications. Current trends, e.g., the availability of high-end computing power via commodity manufacturers who are focused on the business needs of mass-market consumers, are an ineffective and unmanageable solution source for DoD. The mission of DARPA's Information Processing Techniques Office (IPTO) - conduct a focused research and development program that creates a new generation of high productivity computing systems – emphasizes high productivity as opposed to simply high performance. Additionally, of interest to the SDR Forum, is IPTO's articulated vision for the uses of a High Performance Computing System (HPCS) accentuates information superiority with specific applications that include Cognitive Computing and Software Define Radios! In today's complex data sharing environment, specifically complex simulations, the imbalance between computer power and software complexity can result in applications software with poor scalability (utilizing less than a dozen processors for optimized codes) and poor single processor performance (as low as 1% of peak processor performance).
This paper presents the MOPCOM methodology, primarily developed to enable the efficient design of SDR – Software Defined Radio – equipments. Based on UML/MDE approach, it could be advantageously applied for the design of any real-time embedded systems. The MOPCOM methodology defines a set of rules to build UML models for embedded systems, from which HDL code is automatically generated by means of MDE – Model driven Engineering – techniques. The UML/MARTE profile is used to describe real-time properties and to perform platform modeling. Three abstraction levels are defined: abstract, execution and detailed modeling levels (AML, EML and DML, respectively). The second one will be particularly explained and the overall methodology will be evaluated through a SDR case study.
In this year's senior design program at California State University Northridge (CSUN), faculty assigned two sixperson teams with year-long design projects utilizing software defined radio (SDR). Students gained invaluable and in-demand expertise in this emerging technology, while fulfilling the criteria required by the Accreditation Board for Engineering and Technology (ABET). This paper focuses on the advantages to both faculty and students particular to using SDR in a senior design program. Over the last three years the authors have been developing expertise and supervising student projects in SDR. While many schools offer study in SDR for graduate students, the authors felt that SDR was coming into such widespread use that undergraduates would benefit from exposure to the technology. In addition, upper division communications theory courses combined with the required foundations in programming, made the transition to SDR a logical and inevitable step in undergraduate electrical engineering education.
In this paper we present an ultra-low-cost SDR (Software Defined Radio) laboratory that is based on a commercial-off-the-shelf FPGA (Field Programmable Gate Array) development board that is both inexpensive and available worldwide. The total cost of the laboratory is under USD$200, but yet includes complete transmission, channel emulation, reception (coherent and noncoherent) and probing capabilities. Over 15 different modulation types are currently supported. The same, unmodified FPGA board can be used for various undergraduate and graduate courses in digital logic, networking, embedded systems, and microprocessor design, and hence the incremental cost of using the same board for the proposed laboratory can thus theoretically approach $0. The laboratory is aimed primarily at facilitating senior undergraduate and graduate courses and projects, and allows students to get firsthand practical experience in SDR wireless modulation and demodulation techniques. The laboratory is nonetheless powerful enough to allow for SDR research projects. In this context, the laboratory is also particularly useful for universities in developing countries, where budgets are extremely limited as compared to those available in developed countries.
This paper describes a smart radio network that can facilitate communication of radios operating under congested conditions in the 2.4 GHz unlicensed band. The network detects legacy systems spectrally, temporally, and spatially, and implements a novel avoidance technique to reduce or remove interference with the legacy systems. The system was designed by a team of students from Carnegie Mellon University for the 2008 Smart Radio Challenge sponsored by the Software Defined Radio Forum.
The smart use of available radio resources can be used to provide vehicles with real-time on-demand traffic information in a power and cost effective manner. Processing this information to offer route guidance minimizing the total fuel consumption increases the energy efficiency of a car ride. Such traveler information system is not only environmentally friendly; it also gets us a step closer to the Cognitive Radio paradigm, where efficient use of the radio resources meets user demands. This paper proposes an Advanced Traveler Information System (ATIS) that provides vehicles with user specific, on-demand route guidance based on real-time traffic information. Smart use of power and available spectrum, a query strategy that reduces the probability of overloading the system, reliability issues and timing constrains make the realization of the system very challenging. A small scale demonstrator based on cheap technologies such as sensor networks, ISM-band communication systems, and standard equipment for the onboard and central management units has been built in order to provide proof-of-concept.
This paper presents the [email protected] Tech CWT entries in SDR Forum's Smart Radio Challenge. The SDR Forum's Smart Radio Challenge offers student teams the opportunity to design and implement actual radio systems that address issues presented by real world problems to public safety first responders. In 2007, the Smart Radio Challenge problem chosen by CWT concerned recognizing and avoiding primary users while maintaining a communication link with a userspecified minimum QoS. In 2008 we extended the previous year's solution to a network that automatically provided an emergency response communications system in the event of damaged or destroyed infrastructure. Both design experiences contained risks that yielded lessons to be learned. Factors like hardware, software, scenario testing, and design vs. implementation trade offs all had to be weighed. For our 2007 and 2008 entries, this paper presents some of those considerations and choices made, conclusions and lessons learned, and how our experiences might guide future efforts, both in this year's challenge and in other projects.
This paper describes the proposed solution provided by Virginia Tech's Team MPRG in the SDR Forum's 2007 Smart Radio Challenge design competition to address the problem of spectrum accessing for first responders. It also discusses what changes have been made after the competition and what projects have been emerged depending on the research performed for this competition. Traditionally, communication between first response teams following major disasters such as earthquakes or floods is hampered due to the limitation of fixed--frequency legacy radios. These limitations include the protocols assuming static channels which may leave airways gridlocked and useless, interoperability issues among the radios of various public safety agencies, and lack of simultaneous support of voice and data. A novel system named the cognitively intrepid radio emergency network (CIREN) is proposed for deploying software-defined radio handsets that contain voice and multimedia data communications between mobile nodes to mitigate the mentioned limitations. This paper briefly presents the testing and validation of the developed CIREN protocol. It also summarizes the accomplishments from this project and introduces our preliminary research with Lyrtech SFF-SDR board.
Current trends in software radio infrastructures design have evolved over the past several years and resulted in several standards. One of the primary infrastructure architectures is the Software Communications Architecture (SCA) developed in conjunction with and in support of the Joint Tactical Radio System (JTRS) project. One of the basic premises of the SCA and other similar standards, is the specification of a set of common, open interfaces and behavioral requirements. The objective being to define a set of common interfaces to which multiple vendors and suppliers can provide components, develop software, new waveforms, and have a common method for control. While these are valuable capabilities, a common criticism of the SCA is that it incurs too much overhead for small-form factor radio deployment. This paper asserts that one of the factors contributing to the size of the implementation has been the approach to design from the interface rather than designing to the interface.
TUBITAK Reference Waveform (TRWF) is an SCA  based open source waveform implementation. It has been developed as part of a Master of Science thesis in Bogazici University in conjunction with TUBITAK-UEKAE. TRWF project aims supporting SDR developers who are involved in SCA waveforms, and it can be downloaded from SDRForum web site  with no charge. TRWF has been tested to work with SCARI-Open core framework  on Pardus  platform which is an open source Linux distribution of TUBITAK. TRWF can run on a single PC or between two connected PCs. In single PC mode, it allows looping voice or data on the waveform components and in double PC mode it allows voice or data communication between them. It also demonstrates how to apply modulation through configurable parameters.
In this paper, we describe the software architecture and our experience in porting an existing (voice) implementation of the FM3TR waveform to a new software defined radio (SDR) platform – the SDR-4000 from Spectrum Signal Processing. Data communications was not part of the original code base and was included as part of the project. Initially, analog communications was demonstrated at SDR-4000 IF (20 MHz) which included frequency hopping over a 3.2 MHz bandwidth. Then a National Instruments RF upconverter and down-converter was added to each SDR that enabled over-the-air communications between three SDR- 4000 units. The entire project was completed in 9 months. The design and partition of the FM3TR waveform into SCA components across the GPP, DSP, and FPGA hardware of the SDR-4000 is discussed.
In an effort to create a flexible and adaptable cryptographic strategy, the US Department of Defense announced a set of cryptographic algorithms for protecting both unclassified and certain classified national security information. This set of cryptographic algorithms is referred to as Suite B. The Suite B set is based on the cryptographic algorithms approved by the National Institute of Standards and Technology (NIST), thus it is ideally suited as the base for cryptographic interoperability between products manufactured by different vendors. The Harris Falcon III® RF-310M-HH Suite B Compatible Multiband Handheld Radio is the first Software Communications Architecture (SCA) based tactical military radio product to implement the set of Suite B Cryptographic Algorithms. The RF-310M-HH is presently undergoing US DOD evaluation and once certified will be approved to support secret and below voice and data communications. An additional differentiating advantage offered by this Suite B compatible radio product is that it does not require special handling, accounting controls and markings which are typically associated with Controlled Cryptographic Items (CCI). Hence, the RF-310M-HH Multiband Handheld Radio is a Suite B Compatible, non-CCI, electronic communications product designed for secure communications at secret and below level. This paper describes the Suite B initiative strategy and goals as they apply to both tactical military radio communications and public safety radio communications environments. The paper also describes the Harris Falcon III® RF-310M-HH Suite B Compatible Multiband Handheld Radio product, the market needs this product will address, as well as the consideration of ideas for a future set of capabilities.
This paper describes a list of advanced features that can be used to optimize boot time, memory footprint and communication speed for SCA Radios. The paper first describes the most common performance issues and then presents a number of advanced SCA features that can be used to address each issue. Each feature is discussed in details to exhibit under which condition they can best perform. Performance metrics are presented for each feature. Finally, the paper concludes with an outlook on the next wave of advanced optimization features.
The ultimate RF coverage solution for a Public Safety (PS) radio system would provide communications at 100% of the locations where a first responder may be needed for 100% of the time, with perfectly understandable voice quality. This would include 100% coverage within areas such as basements, stairwells, tunnels, and buildings that often have well over 30 dB signal penetration loss. This goal for ubiquitous radio coverage is certainly understandable, since the ability for a first responder to reliably communicate can often determine the difference between life and death. Unfortunately, cost-benefit tradeoffs in designing a public safety radio system, not to mention laws of physics, have traditionally constrained public safety systems coverage from reaching this holy grail of ubiquity. There has been considerable academic research into Cognitive Radio (CR) algorithms which can improve coverage. However, the pragmatic, skeptical public safety user community will not embrace these techniques until they reach the extremely high degree of maturity that is demanded for life-critical communications systems. Therefore, the incorporation of CR into the public safety community needs to be in small increments that are very low risk rather than in quantum leaps. This paper explores some simple techniques that could be useful in introducing CR into the PS community in this manner, rather than more esoteric, complicated, and likely higher risk concepts/algorithms which are presented in other literature.
In contemporary society, Information Systems play an increasingly prominent role. Because they operate at the speed of light, and exchange neither mass not energy, Information Systems are replacing physical systems in many application areas. This paper explores the consequences of exponential growth in information, and proposes Information Process Architecture (IPA) to describe information systems. It also describes Views to describe the complex systems that evolve when previously independent information systems merge. An important characteristic of complex systems is that they are never "finished", so the goal becomes to satisfice rather than optimize system operation, accepting the 80% solution.
Public Safety radios provide "lifeline" communications for Public Safety officers and are expected to work regardless of the RF environment. The RF environment continues to become more crowded with mixed services within and adjacent to the spectrum utilized by Public Safety agencies. The industry is spending over two billion dollars to reorganize the 800 MHz band to separate Public Safety and Cellular Commercial Services operations because of nearfar and out-of-band-emission interference impacting mission critical communications. The United States will complete the transition to digital television this year. The D Block and Public Safety broadband services are adjacent to Public Safety narrowband spectrum creating opportunities for nearfar and out-of-band-emission interference. The new TV whitespace spectrum provides broadband operation opportunity for Public Safety and Critical Infrastructure but in a difficult RF environment in urban and suburban areas with large number of digital TV transmitters which create extremely large in-band signals. This paper will explore the interference challenges that the Public Safety radios are facing and the impact on future receiver designs. Field experience to mitigate interference in the 800 MHz band with improved radio receiver design will be reviewed and the need for increasing performance requirements of Public Safety radio receivers will be explored.
Public safety communications across the world operates over a wide range of frequencies with a variety of signaling and modulation formats. Interoperability between public safety agencies during major disasters is a significant concern [1-4]. Similar problem is also valid in military radio communications, and communication between military radios and public safety radios. Software Defined Radio (SDR) based transceivers can solve this problem with multimode and multiband operations. An SDR based radio capable of handling multiple public and military radio communications and serving as a gateway to bridge various incompatible public safety radios as well as military radios are being developed in The Scientific and Technological Research Council of Turkey (TUBITAK). By using that system an HF radio can communicate with a VHF/UHF radio.
A great variety of wireless systems are currently being used to provide diverse and sophisticated information and communication services. New wireless systems are being standardized for later implementation. In addition, large numbers of radio-frequency identification (RFID) terminals and sensors are being installed everywhere to implement a ubiquitous society. As wireless systems and wireless terminals continue to grow in both number and variety, this will cause a number of problems such as a lack of suitable locations for installing base stations and inter-system interference. To solve these problems, we propose a new flexible wireless system that uses software defined radio technology and cognitive radio technology to support a wide variety of wireless systems. The system processes all received radio waves with network software. A prototype of the system was developed to confirm its effectiveness. We also propose a highly efficient software demodulating method and show its effectiveness by evaluating it with the system prototype.
Software Defined Radios (SDRs) and increasingly Cognitive Radios (CRs) are attractive to replace common digital signal processing hardware solutions. Current SDRs are mostly part of communication systems using hardware front ends containing DSPs or FPGAs. Processing on Desktop Computers only is not common due to the huge amount of processing resources required. Most current Desktop Computers are not able to handle this. We present an approach to realize SDRs on desktop computers with distributed resources. This approach is optimized for multi-core CPUs and already available General Purpose Graphics Processing Unit (GPGPU). In addition, the signal processing blocks are scalable to guarantee real-time performance at varying processing resources at runtime. The novel universal framework can be used to control the output quality of signal processing blocks related to the resource consumption. CR realization could benefit from this approach, too.
A primary appeal of Field Programmable Gate Arrays (FPGAs) is their high computational performance, but there has been a challenge to integrate FPGAs into the SDR hardware and software co-design process. The addition of FPGAs into the design process requires a logical representation of the FPGA as well as an interface to the General Purpose Processor (GPP). Current approaches for interfacing with FPGAs include the use of kernel-level drivers or standardized interfaces. This paper presents an example interface to FPGAs through the use of memory-mapped I/O. This interface is encapsulated as a logical software representation of the FPGA in order to enhance portability across platforms. We will target a Xilinx ML403, where the FPGA is collocated with a PowerPC core and leverage the use of memory-mapped I/O to interface with the FPGA and demonstrate the portable nature of our implementation.
Modern Unmanned Aerial Vehicles (UAVs) have the capability of carrying sensors that produce large amounts of data. A high speed wireless data link is required to transfer this data to other systems for processing. This paper presents an FPGA-based implementation of a QPSK modulator and demodulator to support a high data rate (350 Mbps) relay from a UAV to a ground station. By using high speed ADCs and DACs in conjunction with state of the art FPGAs it is possible to implement all signal processing functions necessary in a modem. We will present the architecture and methodologies used for both the modulator and demodulator and discuss how these algorithms are implemented in an FPGA.
A hardware accelerator capable of carrying out the air-interface processing inside a baseband architecture is presented. The architecture is not only flexible to adopt to the different environments but also carries out the operations quite efficiently. The memory scheme to realize the different set of operations with the same organization is also discussed along with its management by the proposed processor. The performance analysis with respect to the current target technology (FPGA) is described along with a critical analysis describing the limitations of the designed air-interface processor.
In this paper novel approaches to implementation of several processing blocks required in the LTE standards are analyzed and benchmarked. In particular, implementation of the algorithms is assumed to be based on a flexible software based baseband processor. The blocks discussed in this paper are the FFT, the DFT and the Viterbi Decoder. This platform therefore requires the implementation to be completely in software. This poses an important constraint, as typical hardware based implementations use very specific hardware architectural features to minimize the computational latencies. On the other hand a software implementation requires utilization of the general purpose (i.e. load/store) instructions of a processor, as well as its specialized instructions (e.g. butterfly and complex multiplications). Software based platforms have typically limited on chip (fast) memory, that may restrict storage of operating parameters required to set up an algorithm. Therefore novel techniques to maintain all time critical data in the fast memory become necessary in these implementations. The Third Generation Partnership Project (3GPP) has been defining the Long Term Evolution (LTE) for 3G radio access. LTE project aims to ensure the continued competitiveness of the 3GPP technologies for the future LTE focuses on download rates of 100 Mbit/s, upload rates of 50 Mbit/s per 20 MHz of bandwidth, increased spectrum efficiency, and sub-5ms latency for small IP packets.
Among various features offered by the SDR technology, two important aspects related to it are portability of waveform applications and interoperability between SDR platforms. The NATO RTO/IST Research Task Group on Software Defined Radio (RTG on SDR) is working on these aspects in a Software Communications Architecture (SCA) based environment on a mutually agreed test waveform of STANAG 4285. This paper presents the steps taken in order to port the STANAG 4285 waveform from one SCA Operating Environment (OE) to another. This means, moving from one Core Framework (CF), Object Request Broker (ORB) etc to another using the processing element as a General Purpose Processor (GPP). Finally, we present a working demonstration of the STANAG 4285 waveform interoperability between the different OE implementations.
This paper addresses methodologies and applicable metrics that help achieve optimum performance for a Software Defined Radio (SDR) application. Implementers must identify and examine the critical metrics of waveforms and the operating environment(OE) processes that enter into the overall radio communications path in order to successfully determine the performance of a waveform on a Software Communications Architecture (SCA) Radio. Requirements analysis and functional decomposition yields key metrics which lead to a solid comprehension of the user to antenna data paths as well as waveform control. These key metrics are crucial to understanding performance as each individual radio processor and interface must be able to support the waveform performance requirements while also recognizing the unique attributes of that particular waveform. SCA optimization methodologies within the scope of these metrics can enhance SCA performance.
While the Software Communications Architecture (SCA) is a suitable framework for a broad-range of medium and higher capability radio platforms, its use can be non-optimal or precluded on smaller platforms, where software image size, boot time performance or battery life and platform cost become dominant. For these platforms, a lighter-weight solution is desired. On the other hand, the component-based framework and other concepts the SCA provides has proven benefits, and it is desirable to be able to easily port waveforms between an SCA and such lighter-weight frameworks. In this paper, the "Lightweight Communications Architecture", or LCA, is described. This framework is appropriate for use on smaller commercial platforms, with land-mobile radio (LMR) systems being a typical example. From a formative standpoint, the design rationale and trade decisions for LCA are detailed, followed by a description of the framework itself. The paper concludes with a discussion on scalability, patterns for facilitating application portability between LCA and the SCA platforms, and performance metrics.
The application of the Joint Tactical Radio System (JTRS) Software Communications Architecture (SCA)  within the U.S. DoD domain and promulgation across national boundaries throughout the global military radio space highlights the need for effective and efficient SCA test, evaluation and certification models. This paper discusses the current state of SCA test, evaluation and certification in conjunction with the evolving needs of the growing U.S. DoD and international community. Current challenges are identified along with discussion of potential improvements and recommended solutions. This discussion leverages a combination of real-life experience with the testing, certification and fielding of SCA based secure military radios and considerations from various industry and Government perspectives including the Software Defined Radio (SDR) Forum SCA Test and Evaluation Working Group. Harris Corporation has significant experience with the current SCA test, evaluation and certification process; deploying more than 95,000 SCA certified Type 1 secure military radios, including the first certified SCA compliant platform with no waivers, the AN/PRC-152 (c) Hand-held (HH) radio. This radio is also the first and only platform to deploy waveform applications developed specifically for the JTRS Information Repository that have been ported and fielded. The SDR Forum SCA Test and Evaluation Working Group has been actively considering SCA compliance testing and certification in the context of a generic role based process. The SCA test, evaluation and certification current operating model will be reviewed from multiple perspectives, including capacity and cost. Conclusions and recommendations will be offered for consideration.
Much time is spent in diagnosing and isolating waveform resource component problems when they are ported to different platforms. Specifically, integration and testing of temporal correctness and proper transformation of waveform data through components on a target versus what is expected from a simulation model can potentially be troublesome. We present a set of approaches that minimize the time and effort required for porting an SCA or non-SCA waveform to another platform. We also present new unique test tools for SDR development called the Software Defined Radio Tool Suite (STS) that seamlessly provide probes into an SDR and adapter conduits into industry standard tools like MATLAB-Simulink and LabVIEW enabling users to perform diagnostics on a running waveform on real radio targets.
The Software Communications Architecture (SCA) is prominent in development of software defined radio (SDR) waveforms for wireless communication systems. Prototyping of SDR waveforms is an interactive process that benefits from user friendly tools. In this paper, we present one such tool, the Waveform Dashboard. This tool was developed to enable interactive configuration of component properties of SDR waveforms, helping to streamline the rapid prototyping and testing process. The SCA standards define the Common Object Request Broker Architecture (CORBA) interfaces to configure component properties and a means to identify the component properties via the PRF files that enables creation of a generic GUI to work with SDR waveforms. The core framework and tools of the Open-Source SCA Implementation Embedded (OSSIE) developed by Wireless @ Virginia Tech provide a convenient environment for rapid prototyping of SCA-based waveforms. Our tool abstracts the OSSIE core framework and presents an interactive and customizable interface to configure the component properties of SDR waveforms. This paper describes the design and implementation of the Waveform Dashboard and its applications to SDR waveforms.
With the initial generation of reconfigurable software radios now being deployed, an increasing number of flexible and agile communication devices are being introduced into the field. Existing SDR research has focused primarily on single node applications in terms of reconfigurability and performance. Possibilities exist, however, for distributed applications that leverage the increasing flexibility of SDR in a cooperative manner. This paper examines using general purpose commodity hardware as an enabling factor for initial development of new cooperative waveforms. Recent research developments in coordinated multi-node communication are introduced as well as key implementation challenges. Furthermore, a proposed development architecture using an open-source SDR platform for supporting cooperative waveforms is described. Specifically, recent realtime extensions of the Linux operating system are explored for providing necessary timing requirements at the user level on general purpose hardware. Initial timing measurements are provided along with discussion of future development directions.
The motivation for distributed computing across multiple software defined radios (SDRs) evolved from Component and Service based Radio Architectures like the Software Communication Architecture (SCA). This architecture provides an opportunity for value-added services and collaborative communication through its inherent ability to provide distributed data processing across multiple SDRs. We demonstrate a simple proof-of-concept for constructing a software framework for opportunistic signal processing and distributed data processing across SDR nodes. We build this framework on top of the Open source SCA implementation::Embedded (OSSIE), developed by Virginia Tech, for demonstration purposes. A preliminary demonstration implements opportunistic processing of data collected from SCA-based SDR nodes that are connected through a wired or fixed wireless backbone network, laying groundwork for advanced applications like parallel data and signal processing on both wireless infrastructure and Mobile Ad-hoc Networks (MANETs).
Beyond multi-standard operation, SDR for consumer handsets should also aim at multi-radio operation: supporting e.g. HSPA, DVB-T, and WLAN active simultaneously on a shared hardware platform ("radio computer"). In essence, we propose an SDR operating system that provides a virtual platform for individual radios. By means of a technology demonstrator we address dynamic multi-radio operation, incl. key challenges such as unifying critical interfaces, resource management under real-time constraints, and efficiency.
Kosuke Yamazaki - KDDI R&D Labs.
Toward the actualization of flexible multi-band/mode handheld terminals, we have newly developed a Software Defined Radio (SDR) platform in order to verify its low power consumption feature. The developed multi-mode/band SDR platform has only one single baseband processor and is equipped with newly developed control software which handles the limited computational power effectively. As a result, the developed prototype SDR platform can handle multiple radio communication systems (RCS) simultaneously even in the limited computational resource availability.
One of the main challenges in designing a reconfigurable radio is to develop an efficient procedure to reconfigure the radio system to any new waveforms. Proper implementation procedure would allow the radio system to work for different standards while using the same hardware platform. It will also give the opportunity for upgrading the software of the radio system to new waveform standards as soon as they are available and needed. While several attempts have been proposed to implement co-existing waveforms of different standards, it is believed that standardizing the definition of waveforms will lead to a more generic way of implementing smart multi-standard software defined radio (SDR) terminals. Based on this conception, this paper proposes a solution for a generic SDR architecture that can be used to implement smart multi-standard SDR terminals.
In the context of IEEE 802.22 networks, the hidden incumbent problem refers to a situation in which a consumer premise equipment (CPE) is within the protection region of an operating incumbent but it fails to report the existence of the incumbent to its base station (BS). In such a scenario, CPEs within the incumbent's transmission range may not be able to decode the BS signal because of the strong interference from the incumbent signal. Moreover, the CPEs cannot report the existence of the incumbent as their transmission will cause interference to the incumbent. Therefore, these CPEs are unable to report the existence of the incumbent to the BS, and hence the BS fails to detect the presence of the incumbent. To address this problem, IEEE 802.22 prescribes that the BS broadcasts explicit outband control signals on a set of candidate channels and CPEs search for control signals on those candidate channels so that they can send the hidden incumbent detection messages to the BS via one of the candidate channels. In this paper, we present a systematic way of designating the candidate channel sets for the hidden incumbent detection (HID) protocol in 802.22 networks. The proposed approach has two noteworthy features: (1) it allows the BS and the CPE to choose different sets of candidate channels in a distributed manner without message exchanges; and (2) it significantly reduces the size of the set of candidate channels for each 802.22 entity, thus lowering the control overhead of the HID protocol.
Policy-based dynamic spectrum access is one of the spectrum access models being considered by regulators and researchers for regulating the behavior of cognitive radios. This approach to spectrum access decouples the policyrelated components (i.e., policy management, provisioning, and reasoning) from the radio platform. In policy-based spectrum access, the policy reasoner plays a critical role—it assists in policy enforcement and carries out a number of tasks related to policy analysis and processing. One of the most crucial tasks performed by the policy reasoner is evaluating radio transmission requests in relation to a set of active policies. This paper describes the design process and architecture of a policy reasoner. Key features of the proposed policy reasoner include: (1) policy conflict detection and resolution; and (2) ability to process underspecified transmission requests and compute the corresponding constraints.
Low Duty Cycle (LDC) algorithm is interference mitigation technique, which can reduce the average interference to the existing radio systems by using lowering pulse repetition interval or pulse occupation time. In this paper, the coexistence environment between low data rate ultra wideband (UWB) communication system such as wireless sensor network, body area network (BAN) and the existing wideband system using orthogonal frequency division multiplexing (OFDM) such as 4th generation mobile cellular system (4G) is considered. In order to analyze the interference mitigation capability of LDC algorithm with impulse based UWB (LDC-UWB) system, the frame error rate (FER) of wideband OFDM system is examined for two types of LDC-UWB system: the signal with random polarity such as binary pole signals and without random polarity such as mono pole signals. We present that LDC algorithm is an efficient interference mitigation technique for low data rate UWB communication via computer simulations regardless of definitions of transmitted energy of UWB communication system, and also that the signal with random polarity is suitable for LDC-UWB system to mitigate interference to the other radio systems. We further investigate the adequate duty cycle of LDCUWB system for each definitions of transmitted power of UWB communication. Moreover, we propose the spectrum management techniques by using adaptive rate controlled LDC-UWB. The average interference from UWB to wideband OFDM systems is reduced by using LDC algorithm. Simultaneously, the frequency spectrally notching out the existing system operational bandwidth frequency avoidance technique can be formed by adaptively-changed duty cycle of LDC-UWB system. Therefore, we present that the interference mitigation capability of LDC-UWB system can be improved.
This paper presents a spectrum sharing criterion for protecting the capacity of the primary terminal with various signal-to-noise ratio (SNR). The proposed criterion determines allowable interference toward the primary system based on a capacity conservation ratio (CCR). The CCR is a ratio of the capacity of the primary terminal without the secondary user interference and that with the secondary interference. The performance of the primary terminal with high capacity can be maintained to a high level with keeping the CCR. On the other hand, the performance of the terminal with low capacity also can be maintained to a small capacity degradation by using the same CCR. In addition, a power control method of the secondary system based on CCR is proposed. Secondary system can achieve increasing on its own capacity and can avoid the interference toward the primary system using this method. However, the proposed method cannot avoid the interference when the location information of the primary and secondary terminals has a large error. In order to solve this problem, we consider a power control method, which consider the location error based on worst case scenario of the terminal location.
Software Defined Radio and Dynamic Spectrum Access technologies have significant potential to enable emerging vehicular network technologies. Capability to sense and manage spectrum in real time is one of the most important requirements for vehicular dynamic spectrum access technologies. In this paper we propose a simple multiresolution energy detection algorithm for sensing wideband channels. Through extensive experiments with GNU radio software and The Universal Software Radio Peripheral, we evaluate the performance of an energy-based spectrum sensing algorithm depending on sensor location, channel diversity and interference with transmitters and sensors placed in multiple locations. To further validate the results we provide comparisons between the information extracted by the proposed sensing algorithm and by spectrum data collected from a spectrum analyzer. The experiments are performed in the unlicensed ISM band between 2400MHz to 2500MHz over the newly developed cognitive radio testbed platform at Rutgers University.
In cognitive networks, opportunistic network devices can be programmed to take advantage of licensee idle time and dynamically adapt their operational parameters to improve transmissions. In order for this to be successfully accomplished, it is critical that these idle periods be detected reliably. Promoting this requirement, the work presented here proposes a cooperative detection mechanism for signals transmitted by the licensed system, through the use of location sensing equipped devices. Such devices can provide information for transmission and control of the opportunistic network devices to limit the interference in the licensed system. The simulations performed show that in an ad hoc scenario it is possible to improve the quality of opportunistic network communications by maintaining the interference within the specification limits.
Spectral analysis and channelization are two common tasks performed in many software defined and cognitive radios. These tasks are usually performed sequentially by controllers that reconfigure the algorithmic resources of a polyphase filter and a fast Fourier transform. We present here a receiver structure that performs both tasks simultaneously in the common software.
As commercial SDR products mature, new applications will look to the technology as a means to simplify future designs. At the same time SDR is gaining traction, so are MIMO consumer devices for 802.11n, 802.16e and LTE. This paper explores some of the trade-offs SDR System architects need to consider when designing next generation SDR MIMO RFICs for mobile devices and where the technology can enhance operation for these modes.
The main advantage of Software Defined Radio (SDR) is the ability to implement new waveforms without changing the hardware. The flexibility offered by SDR hardware is useless unless a designer can easily take advantage of it. Unfortunately, many of the currently-fielded SDR platforms use proprietary interfaces and have a high barrier to entry for 3rd party developers. Indeed, despite the programmability of the radios, the customer is often locked into the vendor for developing techniques and software for the radio. In this paper we define a simple standard for describing the physical layer of the waveforms implemented on an SDR. The Extensible Markup Language (XML) has been selected to represent the standard. The core of the standard has now been defined, covering hundreds of aspects from modulation to coding and framing. An interactive website has been created to allow multiple contributors to add and modify the standard and to allow collaboration with colleagues in industry and academia. This paper describes the philosophy behind the standard, introduces the XML notation and paradigms for both configuring a radio and querying its status and capabilities. The main goal of the paper is to solicit input from interested parties and to foster the acceptance of this open and free standard.
Spatial multiplexing multiple-input-multiple-output (MIMO) communication systems have recently drawn significant attention as a means to achieve tremendous gains in wireless system capacity and link reliability. The optimal hard decision detection for MIMO wireless systems is the maximum likelihood (ML) detector. ML detection is attractive due to its superior performance (in terms of BER). However, direct implementation grows exponentially with the number of antennas and the modulation scheme, making its ASIC or FPGA implementation infeasible for all but low density modulation schemes using a small number of antennas. Sphere decoding (SD) solves the ML detection problem in a computationally efficient manner. However, even with this complexity reduction, real-time implementation on a DSP processor is generally not feasible and high-performance parallel computing platforms such as FPGAs are increasingly being employed for this class of applications. The sphere detection problem affords many opportunities for algorithm and micro-architecture optimizations and tradeoffs. This paper provides an overview of and FPGA implementation of a sphere detector and channel matrix pre-processor applicable to the 802.16e air interface protocol. The architecture of the design is presented along with resource utilization data and BER performance curves.
fred harris - San Diego State Univ.
A receiver must estimate a number of essential unknown valued signal parameters from a received signal in order to demodulate the information in that signal. These parameters include, signal strength, carrier frequency and phase, sample time frequency and phase, and channel gain and phase distortion terms responsible for inter-symbol interference. These parameters can be extracted from a preamble training signal designed for their fast acquisition. This paper describes the signal structure and the signal processing required to rapidly estimate these parameters and how they are incorporated in appropriate processing block to support the demodulation functions.
The Fast Fourier Transform (FFT) plays a central role in OFDM systems, and for today's high-speed waveforms a parallel HW-implementation of it , either in ASICs or FPGAs, is often imperative. OFDM systems frequently employ so-called "Real-Valued FFTs" which exploit that the time-sequence is real-valued and the frequency-sequence is conjugate complex. In addition a parallel/serial conversion has to be performed to accommodate the discrepancy between serial sample streams and the block processing nature of the FFT. Pipeline architectures for the FFT perform the required parallel/serial conversion as a byproduct and lend themselves to efficient HWimplementations. The Cooley Tukey FFT of length N=2 , integer, is one of the most widespread FFT algorithms for OFDM systems and allows for an efficient pipeline implementation. In this paper it will be shown that a different algorithm, the Bruun- FFT of length N=2 , integer, also lends itself to a very efficient pipeline architecture that exhibits chip area savings of up to 50% over the Cooley Tukey FFT.
There has been considerable interest in software based control techniques to lower the power consumption in SFF SDRs. This paper will present a set of novel techniques which allow any conventional SDR platform and waveform to negotiate waveform demands while minimizing the power usage profile. The techniques described will include combinations of ideas such as adaptive switching, waveform mode cognizance and a new form of experimental reflexiveadaptive power minimizing middleware. The results of the research will be demonstrated with experimental results and a demonstration at the SDR Forum conference. A blueprint adaptive power control specification will also be presented.
Software-defined radios (SDRs) present a new paradigm in the implementation and resource management of wireless communication systems. In doing so, they introduce increased interference risks because of both their ability to access wide spectral bands and their vulnerability to software configuration errors and malicious attacks. A necessary element for SDR mainstream deployment, is the formulation of adequate policies to prevent unauthorized software changes without placing unreasonable regulatory burdens on designers and manufacturers In this paper, we introduce novel approach for assessing the integrity of SDR software execution by monitoring their dynamic power consumption. The approach relies on extracting distinctive power consumption features and then determining whether they correspond to authorized behavior by using pattern recognition techniques. This approach provides a mechanism to detect the execution of unauthorized software and support regulatory compliance. Preliminary results show the correct identification of basic software routines executing on different platforms. Discriminatory features are extracted in the time domain and from the execution on basic evaluation boards. These results corroborate the existence of power fingerprints and motivate further research on this topic.
Unlike traditional digital radios, where the waveforms are implemented in low power hardware such as ASICs, software defined radio (SDR) designs have to be concerned with the waveform computational complexity. Consequently, in SDRs, where the system power consumption is influenced by both the computational as well as communication hardware power consumption, it is important to understand the tradeoff between the two power consumption components. In this paper, we exhibit the tradeoff in the context of channel coding where the decoder complexity can impact the transmit power required in order to meet a given bit-error-rate (BER). Specifically, we consider viterbi decoding and soft-in-soft-out (SISO) BCJR iterative decoding of minimum shift keying (MSK) symbols where the traceback length and the number of iterations of the decoder can be tweaked in order to vary the computational execution time.
Recently, demand has increased for a mobile terminal that can adapt to a variety of different wireless communication systems. In order for the mobile terminal to seamlessly switch wireless communication systems, depending on the condition of the wireless channel between the mobile terminal and the base station of each system, simultaneous operation of both the processing for communication with the system that the mobile terminal connects to and periodically measuring the received signal power to find other candidate systems is imperative. The computational complexity for this measuring operation should be reduced in terms of total power consumption. In this paper, we propose an effective method of measuring the received signal power. In our proposal, the measurement interval changes depending on the variations in the wireless channel. This enables a reduction in [operation required for the measuring operation while maintaining the tracking capability of the wireless channel. To demonstrate the effectiveness of our proposal, a computer simulation was executed. The results show that the proposed method realized good tracking performance while reducing the amount of the processing numbers required for measuring the received signal power.
This paper shows how cognitive radio (CR) can help to optimize system power consumption of multiple input multiple output (MIMO) communication systems. This paper mathematically formulates the system power consumption minimization problem under a rate constraint for MIMO systems. Optimal and suboptimal algorithms are developed to solve the optimization problem numerically. The simulation results show that significant power savings (up to 75% for a 4× 4 MIMO system with Class A power amplifiers) can be achieved compared to conventional allocation schemes. The results also show that the presented suboptimal algorithms can achieve power savings comparable to the optimal algorithm with lower complexity.
In perspectives offered by multi-channel SDR set, digital signal processors (DSP) need to simultaneously execute several radio physical layer (PHY) components. One major challenge in integrating together such DSP applications is the real time requirements that must be satisfied. In order to satisfy these real time requirements, specific needs of real time scheduling analysis arise because of simultaneous executions on the DSP platform. In this paper, we propose a design approach, which allows the real time scheduling analysis of tasks on DSP. A realtime scheduling simulation tool is also presented to help SDR applications designers; it is able to test the feasibility of tasks whose execution times, deadlines, and minimum separation times are different from one phase to another. The tool is also able to verify (by simulation) the real-time behavior of tasks implemented in DSP and scheduled according to dynamic priority scheduling. We also discuss the impact of the study on the capabilities of SDR equipments.
Jörg Lotze; Suhaib A Fahmy; Baris Ozgul; Linda Doyle - Trinity College Dublin; Juanjo Noguera - Xilinx, Inc.
Femtocells are a promising solution to provide high coverage and high data rates inside consumer's homes while cutting operator costs significantly. Next generation Long Term Evolution (LTE) femtocells are likely to be deployed in GSM spectrum, increasing frequency utilisation and allowing a smooth transition to LTE. This paper proposes to use a spectrum sensing technique specialised for LTE signals to avoid interference between neighbour femtocells without operator intervention. Simulation results of the detection characteristics are given. A demonstrator has been implemented on a Xilinx ML507 Virtex 5 prototyping board, using our flexible FPGAbased cognitive radio framework, which allows to use runtime reconfiguration of the FPGA to switch between sensing and normal operation. It demonstrates the sensing algorithm on a real platform.
Multi-band, reconfigurable cognitive radio (CR) technology has been identified as offering key solutions to Public Safety spectrum access problems. However, CR technology invokes concerns about the ability to securely control devices with Dynamic Spectrum Access (DSA) capabilities potentially operating autonomously across multiple frequency bands. To alleviate these concerns, an end-to-end, Cognitive Radio Access Management (CRAM) subsystem is presented that focuses on secure, flexible and userfriendly policy-based control mechanisms. On one end of the subsystem, policy conformance enforcement is embedded at the edge of the CR network onto CR devices by leveraging device-understandable, XML-based rules and constraints. On the other end, user-friendly policy authoring and administration tools are available to a wide range of Public Safety stakeholders to create, disseminate, and validate policies before, during and after they are loaded and run on CR devices. Throughout the subsystem, multiple layers of reliable security measures are employed to further ensure trust that the policies are valid and work properly.
Genetic Algorithm based weighted optimisation strategy for collaborative spectrum sensing is presented in this paper. It is shown that imperfect reporting channel and different mean SNR of secondary users have direct impact on the performance of collaborative spectrum sensing. Under channel fading, optimum collaborative spectrum sensing problem is formulated as a nonlinear optimisation problem and genetic algorithm is proposed as a solution approach. For a given probability of false alarm and given channel conditions, optimal weights are assigned to the secondary users to maximise global probability of detection at the fusion centre. The simulation result shows that the performance of proposed optimised collaborative spectrum sensing scheme yields higher collaborative gain.
In this work we use hidden Markov Models (HMMs) to model and predict the spectrum occupancy of licensed radio bands. The method can dynamically select different licensed bands for its own use with significantly less interference from and to the licensed users. It is found that by predicting the duration of spectrum holes of primary users, the CR can utilize them more efficiently by leaving the band, that it currently occupies, before the start of traffic from the licensed user of that band. The impact of CR transmission on the licensed users is also presented. It is shown that significant SIR improvements can be achieved using HMM based dynamic spectrum allocation as compared to the traditional CSMA based approach. The results obtained using HMM are very promising and HMM can offer a new paradigm for predicting channel behavior, an area that has been of much research interest lately.
In this article, a novel spectrum awareness engine is proposed that can be integrated in cognitive radios. Since characterization of the interfering signal will help with overcoming their effects, blind signal detection is described in the proposed engine. The proposed engine is intended for the ISM band. A study of the major ISM band wireless standards is been performed, and the main key identifying features of each standard is marked. A feature detector for different wireless standards is proposed. Finally a decision making process is proposed to utilize all the detected features before making the decision of the detected signal identity.
The spectrum scarcity problem emerged in recent years. Spectrum access scheduling addresses challenges arising from spectrum sharing by interleaving the channel access among multiple wireless systems in a TDMA fashion. Different from cognitive radio approaches which are opportunistic and non-collaborative in general, spectrum access scheduling proactively structures and interleaves the channel access pattern of heterogeneous wireless systems, using collaborative designs by implementing a crucial architectural component – the base stations on software defined radios (SDRs). We discuss our system design choices for spectrum sharing from multiple perspectives, then present the mechanisms for spectrum sharing and coexistence of GPRS/WiMAX and GPRS/WiFi as use cases, respectively. Simulations were carried out to prove that spectrum access scheduling is an alternative, feasible and promising approach to the spectrum scarcity problem.
In this paper we describe a "software-based" implementation of a 2-FSK continuous waveform. The base band processing is done in the DSP and the interpolation / decimation, and frequency translation is implemented in the FPGA. The AD and DA interfaces are situated in an intermediate frequency of 70 MHz. For the AD conversion a band pass scheme is used. The DA conversion is a low pass filtering although the signal is digitally modulated at the frequency of 70 MHz. Sliding Goertzel algorithm is used in the 2-FSK receiver as a pass band filter. Symbol Synchronization is based on an Early – Late algorithm. Viterbi Coprocessor available in the DSP is used to implement a convolutional decoder. The architecture and most significant blocks are explained in this paper. Finally some results of the implementation are given.
Software defined radio (SDR) solutions for mobile devices need to be energy efficient to extend battery life. At the same time, SDR solutions need to support easy portability of waveforms (WFs). To address these contradicting needs of efficiency and WF-portability, a novel concept, the Nucleus concept, has been proposed. The Nucleus concept, which is library based, provides flexibility in implementing a WF by making available efficient implementations for critical components of a WF. Due to the existence of a huge design space in mapping a WF to a hardware platform, tool assistance is highly beneficial, if not mandatory. An important step towards a mapping-tool is to analyze, understand and precisely capture the requirements of a tool in accordance with the Nucleus concept. This paper contributes a methodology for a tool-assisted mapping and evaluation in the Nucleus concept. Various information sources and the information that needs to be captured by the mapping-tool are identified. A two-level evaluation is proposed to enable fast convergence to an ideal mapping efficiently.
Modulation identification is one of the most challenging steps for blind receivers. If frequency offset is present in the system, this process becomes even more difficult. The proposed method is based on the estimation of the modulation types for quadrature amplitude modulation (QAM) even before correcting the frequency offset. The modulation order is estimated using the probability density information (pdf) of the amplitude of the received signal. As carrier frequency offset causes a cumulative rotation for every successive sample, amplitude variation of the signal gives very important clues about the order. Using the density information and the number of clusters, the modulation order is estimated. After estimating the modulation type, frequency offset is corrected. If the constellation mapping of the incoming signal is circular, an algorithm defined for phase shift keying (PSK) mappings is used; on the other hand, if it is rectangular, algorithms defined for square constellation mappings are used.
A flexible base station (FBS) is an enabling element for the realization of cognitive radio networks. It consists of a multi standard transceiver and a flexible baseband processing (FBP) unit. The key features of such a FBP unit are the support of multiple radio standard processing chains (e. g. Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE)), the dynamic load balancing between these standards, the flexible assembly of radio functional modules and the simple extension of radio functional modules and thus the radio standards. The paper describes an experimental FBP design and the necessary applications for the control of this design. The described design will be mainly realized with field programmable gate arrays (FPGA) and the partial reconfiguration (PR) technology. For that, the FPGA area will be divided into smaller variable reconfigurable areas and an interconnection system between these variable areas will be presented. The flexibility of the baseband processing can be further increased by introducing parameterization of the functional modules where appropriate. A framework is required to control the FBP. The corresponding approach presented in this paper is the introduction of an FPGA embedded framework. This framework operates on an embedded processor and will be controlled by higher layer applications. The corresponding interface based on the Object Management Group (OMG) software radio specification will be also briefly described in this paper. Furthermore an application for the direct control of the framework will be introduced. This application offers a graphical user interface (GUI) and uses the OMG-based interface mentioned above. The last topic inside this paper is an approach on modeling and performance analysis for verification of flexible baseband processing systems. This topic discusses the exploration of the design space for flexible reconfiguration architectures.
IEEE 802.11g is a widely used standard for Wireless Local Area Networks (WLAN). In this paper, we discuss a software implementation of an 802.11g WLAN baseband receiver on the Sandbridge SB3500 processor. The Sandblaster SB3500 is a compact and power-efficient system-on-chip platform tailored for wireless devices. We briefly describe the structure of SB3500. After a discussion on the structure and performance of equalizers, we introduce the details of the software defined implementation of the 802.11g implementation on the SB3500.
A software architecture to rapidly develop and test radio networks in real and physical environments is proposed. Radio network terminals are developed in software and run on generic hardware to maximize reconfigurability. Due to the software nature of the radio terminals, radio networks can be simulated in a virtual environment, where physical channels are emulated by software entities. Without any changes to the code base, the same waveform can also be run in a real, physical environment. This feature is used to rapidly switch between real and virtual networks, thus bridging the gap between simulation and physical reality. Aspects of the proposed system are implemented and demonstrated with the GNU Software Radio framework.
A handheld software defined tactical VHF/ UHF radio used for AM/FM/PM line of sight communications is transformed into a single sideband HF band radio for HF 2G and 3G ALE networking. Military radio convergence presents real challenges to aggregation of widely variant narrowband waveforms. This paper discusses the hardware adaptations that allow a handheld VHF radio to act as the core radio of a HF band Manpack by simple software upgrade. This is an architectural discussion of how first generation software defined radios (SDR) are showing the promise that the SDR community has been promoting. Discussion covers baseband hardware architectures and the advantages and limitations of the current best practice software definable modem design. The addition of external frequency translation and PA design are used to transform the base radio. This paper discusses the mix of signal processing software and hardware filtering used to complete the radio transformation.
We present LiveKB, a framework for interaction between a reasoner and Software Defined Radio, which allows for use of dynamic facts that correspond to particular parameters within the SDR software, without having prior knowledge of its data structures. LiveKB is platform independent and domain API neutral, which allows it to sustain technological changes within a particular domain.
The objective of this paper is to present a development effort to ITS application carried out by the authors at SMIT towards a latest category of vehicles which embeds three technology systems viz. Radar, Communication and Radiometer for reliable ITS operation. Radar for collision avoidance and cruise control, Communication for driver assistance like positioning, navigation and passenger needs like internet, mobile TV etc. and Radiometer for sensing smoke/gas pollution. SDR is used as the central control unit of the embedding system, exploiting it as a reconfigurable hardware to operate in three modes – radar, communication & radiometer as when required. The entire base band processing, integration, coordination of the three systems and mode of operation is carried by the SDR, where conventional methods if used would increase system complexity/size, reducing system reliability and flexibility. Radar and Communication modes have been realized. Development efforts are being carried out for Radiometer operations.
A Software Reprogrammable Payload (SRP) is comprised of a Software Defined Radio (SDR) which is deployed on a mobile platform, such as an airplane or unmanned aerial vehicle (UAV), and includes a library of user-selectable applications. SRPs are useful because software applications can be written and changed, when necessary, to facilitate communication between ground users when other forms of communication are not available. Additionally, SRPs allow a user to switch software applications dynamically. In this paper, an SRP is demonstrated through flight on a Cessna Skymaster. The demonstrated software radio used GNU Radio, and included the following applications: analog relay with interference mitigation, Automatic Identification System (AIS) data collection and downlink, and a software router.
One of the most significant promises in today's integrated broadband wireless networks such as WiMAX is in providing Quality of Service (QoS) guarantees. Using scheduling algorithms to provide QoS guarantees, wireless networks are able to integrate applications with a wide range of traffic characteristics. Deficit fair priority queue (DFPQ) provide directional based priority and service class differentiation. However, the environment for wireless networks is variable both in time and space so that the effectiveness of scheduling algorithm maybe invalidated by bad channels conditions. This paper proposes a channel aware deficit fair priority queue (CA-DFPQ) packet scheduling architecture for the QoS management for the Mobile WiMAX. The proposed scheduling is an extension of DFPQ found in literature, suitably modified to provide differentiated service even in non-ideal channel conditions. The modified algorithm together with a proposed mechanism for error compensation in WiMAX error-prone channels is designed to provide directional differentiation and service class priority.
The work presented within this paper was performed within the Work Package 1 (WP1) of the End-to-End Efficiency (E3) project . It aims at assessing the value propositions offered by Cognitive Radio Systems, defined in the context of E3. The paper is organized in two main sections: • The first section of the document presents an analysis of the consolidated feedbacks given by mobile industry stakeholders to a questionnaire on Cognitive Pilot Channels and specific autonomous functionalities. • The second section explores the quantitative gains that could be expected from specific Cognitive Radio Systems. Sensitivity analysis to given parameters are undertaken thanks to a generic cost model.
An ontology defines the basic terms in a domain and the relationships among them. It is used to share information among people, machines, or both in order to facilitate further analysis of the domain knowledge. In the cognitive radio domain, two radios can achieve interoperability by exchanging the knowledge about their communication parameters and protocols. The knowledge, which includes information like the capabilities, configuration and system state of the radio, can be used to reconfigure the radios in a flexible way. Although there is some research on developing ontologies in the cognitive radio domain, the language used to model the ontology, e.g. UML, is not sufficiently machine-understandable since UML does not have formal, computer-processable semantics. In this paper, we describe our efforts to develop an ontology for the cognitive radio domain, specifically, for the lower layers (physical layer, data link layer and the network layer), using a formal declarative language. This ontology will provide extensible standard vocabularies, which will server as the basis for rule-based inference and constraint solving capabilities. Since there are many alternative ways to model the knowledge in a domain, and since the criteria for choosing the best solution are application-dependent, we considered and compared different approaches to conceptualize the knowledge of the cognitive radio domain based on various criteria, like the extent of the coverage of the knowledge of the domain, the ability of inferring facts that are not explicit in the knowledge representation and the extendibility of the ontology. This paper summarizes some of the results of our analysis.
Algorithm developers for spectrum sensing algorithms are faced with many challenges due to real-world environments that include multiple dynamic signals under dynamic fading conditions. This paper will explore a Cognitive Radio algorithm design and test methodology using simulation. The radio's spectral environment can be generated from live recordings, simulated signals, or a combination of the two. A sensing algorithm is then simulated to evaluate how well it can detect emitters and correctly identify usable spectrum. This combined simulation and test methodology enables algorithm developers to develop and evaluate their algorithms in simulation with recorded real-world signals, using the flexibility of simulation to explore radio spectral environment "what-if" scenarios. Please note that this paper has been abstracted from an Agilent whitepaper publication.
This paper presents results of the European project E3 (End-to-End Efficiency). Cognitive Radio Systems that have certain freedom for autonomic spectrum and technology usage decisions get more and more important. Especially opportunistic spectrum access has been extensively discussed during the last years. One of the results is that even those radio systems that act at a very high degree of autonomy need still some control. This results from the fact that a reliable resolution of coexistence issues with primary systems as well as between cognitive systems is required. This paper considers the functional architecture that provides a frame for implementation of the remaining control in Cognitive Radio Systems.
High quality communications among a diverse set of cognitive radio (CR) nodes is permitted while minimizing interference to primary and other secondary users by employing Dynamic Spectrum Access (DSA) in a Dynamic Cellular Cognitive System (DCCS). DCCS can be used for, not limited to white space devices communications. Diverse device types interoperate, cooperate, and communicate with high spectrum efficiency and do not require infrastructure to form the network. The dynamic cellular cognitive system can expand to a wider geographical distribution via linking to existing infrastructure. The DCCS can quickly form a network to accommodate a diverse set of devices in natural disaster areas, for example, earth quake and Katrina. It can also recover the infrastructure in a blind spot, for example, subway or mountain area. Portable size and cost reduction enable the feasibility of its commercial applications.
In this paper, we present the design of a Software Defined Radio (SDR) architecture that is used for geotagging camera images. In this architecture, only the radio frequency (RF) front-end of the SDR is installed on the camera to reduce the power required for collecting Global Positioning System (GPS) geolocation data. A brief snapshot of the GPS signals is collected when a picture is taken and is later uploaded to a central server for processing by an SDR when the camera connects to a network for uploading its digital images. This paper covers the design of this low power digital image geotagging system architecture and the SDR used to perform the Global Navigation Satellite Systems (GNSS) processing. GNSS tracking results are also included showing operation in different environments, including under tree canopy and in urban environments. Test results are presented demonstrating the performance of this geotagging solution compared with conventional GPS chip set approaches.
Global Positioning Satellite (GPS) receivers have entirely changed the way were used navigating. They are part of our day to day life and we find them in the most common as well as the most unexpected areas of applications ranging from less accurate E911 to the most accurate receivers employed in monitoring the tectonic plates movements. Due to the computational complexity, implementing the GPS receivers in low cost low power digital signal processors targeting smart phones and PDAs is still prohibitive. GPS receivers are implemented in HW, employing multiple parallel processing channels. Each channel is responsible for tracking and demodulating one satellite. For economic reasons, in some applications, one channel can be time shared for more than one satellite or, in most expensive receivers thousands of parallel processing channels are employed to improve the time to first fix. Also, in multi protocol communication systems the HW implementation becomes less attractive due to extra chip cost and PC board area consumed. In this paper we present a pure SW implementation of the GPS receiver, implemented in SB3500 DSP, with time to first fix comparable if not better then the existing, technologically most advanced GPS receivers with the same positioning accuracy.
RFMD has demonstrated broadband GaN HEMT power amplifier with 10 W and 25 W output power and 2 GHz instantaneous bandwidth. The RF3826 is a 10 W device that obtains 12 dB gain, 0.05–2.0 GHz bandwidth, and 9–11 W continuous wave (CW) 100% duty cycle output power over the band with and 54–66% drain efficiency. The amplifier is packaged in a ceramic SO8 package and contains a GaN on SiC device operating at 28 V drain voltage with a GaAs integrated passive matching circuitry. The RF3833 is a 25 W device designed for 48 V drain voltage and obtains 22–32 W CW with 53–69% drain efficiency over the band. This amplifier is packaged in a Cu base package to handle the relatively higher power. These amplifiers are targeted for multi-band communication systems covering VHF / UHF / L-bands. Applications include wideband digital cellular infrastructure and handheld and mobile radios.
This paper presents MASTR V – a new SDR base station for Land Mobile Radio (LMR) Systems, designed and developed by Harris Corporation. This base station uses an IP-based communication framework (including an IP backplane) to enable a completely modular software and hardware architecture. The modular design affords the station flexibility in redesign and development and allows the station to be easily adapted to different operating scenarios. The base station also incorporates several SDR design methodologies including the use of Direct Digital Synthesis (DDS), a FPGA designed using Simulink-based tools, digital demodulation, digital transmit power control, digital automatic gain control (AGC), a novel polar PA linearizer, and digital calibration. This allows the station to be software-reconfigurable for multiple, potentially arbitrary, modulations within the MASTR V's bandwidth capabilities including P25 Phase I and II, OpenSky®, High Speed Data EDACS, Analog-FM, WCQPSK linear simulcast and QAM.
We propose a new approach to solving the spectrum scarcity problem, called spectrum access scheduling (SAS), which allows heterogeneous wireless systems to share the same spectrum band using protocol engineering methods. SAS treats the collection of wireless systems as an ecosystem, and optimizes the system performance by collaborative designs. The key architectural component in realizing SAS is the base stations of the wireless systems. We implement a base station using state-of-the-art software and hardware components, namely GNU Radio, OpenBTS and USRP software and hardware platforms, and demonstrate the feasibility of the coexistence of two heterogeneous wireless systems, GSM and CSMA, in the GSM-900 band.
This paper presents a transceiver model that comprises two time-interleaved analog-to-digital converter (ADC) systems to sample the inphase and quadrature signals in a digital receiver. Random data is used as the information signal and quadrature amplitude modulation (QAM) is employed as the modulation scheme. To overcome the performance degradation induced by converter mismatch, two different reconstruction techniques are proposed. An analytical Discrete Fourier Transform description of the non-ideal sampling process is presented to design reconstruction filters that mitigate distortions, caused by non-ideal sampling. Moreover, a novel design technique is presented that allows for the design of reconstruction filters in the time domain. This design methodology proves to be less involved and more concise compared with the frequency based approach. Furthermore, simulation results are presented illustrating the severe degradation of the receiver performance due to moderate converter mismatch for 16 and 64 QAM when no reconstruction filters are employed. Finally, it is shown how the decreased symbol error rate (SER) can be significantly improved by utilizing the proposed reconstruction filters.
A digitally enhanced sigma-delta ADC for narrowband LTE/WiMAX wireless receivers is proposed. A 5th order 2- bit continuous-time complex bandpass sigma-delta modulator is used to achieve the required dynamic range, attenuate the interferers, reject the image and meet power dissipation and area constraints imposed by mobile devices. Dithering and adaptive line enhancement techniques are employed to compensate for I/Q channel mismatch. The simulation results after calibration show an improvement of 16.93 dB in SINAD and 21.6 dB in image rejection.
Recent advances in the area of power-efficient analog-todigital converters (ADC) for software-defined radio (SDR) front-ends are presented. A novel charge-sharing successive approximation (SAR) ADC architecture eliminates all power bottlenecks of the classical SAR implementation and reaches a figure of merit (FoM) of only 54fJ/conversionstep. As a converter that requires less analog baseband filtering, a multi-mode reconfigurable continuous-time (CT) sigma-delta (ÓÄ) ADC is presented that reaches up to 10MHz bandwidth and retains low power consumption over all modes. Finally, as a demonstrator for a true ADC-at-theantenna system, a 6th order RF bandpass Sigma-Delta ADC operating on the 2.4 GHz ISM band suitable for direct RF sampling is proposed.