SDR'12-WInnComm-Europe Papers and Tutorials
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Thursday, June 28
Session 3.1 - Shared Spectrum Access
10:30 - 12:00 (Netherlands I)
Opportunistic radio transmission in the TVWS for first responders' assistance (Presentation Only)
Rosolino Lionti (CEA, France); Marc Laugeois (CEA-LETI, France); Dominique Noguet (CEA LETI, France); Vincent Berg (CEA LETI, France)
Fire fighting requires fast response time and resources adapted to the particular situation. The deployment of heavy means is decided through a discussion between first responders and the stakeholders located remotely. As a consequence there is a need for accurate information to select the best solution in the shortest possible time. Video transmission is a valuable add-on to existing audio information. Because of the hazardous environment of a fire, the task of video shooting and transmission is assigned to fire-fighters who have the ability to operate under such difficult conditions. This requires embedding the sensors and transmitter in the first responders' equipment. Indoor transmissions are prone to multipath propagation, this effect combined with particles and debris in suspension in the air resulting from combustion, reinforced concrete, bad clearance of embedded antenna, limited radiating power, limited weight, etc, makes the development of a radio system very challenging. Depending on the structure and geometry of the buildings and indoor furniture and objects, the electrical field is more or less absorbed/transmitted/rotated. As a consequence multipath propagation "depolarizes" the electrical field vectors between transmitter and receiver, if nothing is done to mitigate this effect, the reliability of the transmission is seriously compromised. Moreover in the case of on-the-body worn devices, the polarisation is continuously changing and needs to be compensated. CEA-LETI has developed a dual polarized antenna embedded on the transmitter and larger antennas with dual polarisation at the receiver end. By adding spatial diversity (two Rx antennas) to polarisation diversity, the gain on SNR is in the range of 5 to 10dB, moreover the area coverage is significantly enhanced. The result is a 1x4 SIMO architecture, composed of one transmitter and four receivers. Each receiver can intercept a path with different polarisation from the three other receivers. In order to make the most of each contribution, a Maximum Ratio Combiner has been implemented. The combination makes use of the radio signal and the gain level of each receiver. This presentation will develop the SIMO architecture of the radio technology that has been designed by CEA-LETI in the TVWS. TVWS UHF bands have been selected thanks to their good propagation properties which enable to reduce the transmitted power of the worn equipment without sacrificing range. The public safety TVWS testbed deployed at CEA-LETI will also be addressed. The communication link involves the specific TVWS radio link between the first responder and the local head, and a second long range wireless hop between the local and remote heads using off-the-shelf WiMAX equipment. This 2-hop radio system enables long range end-to-end rescue monitoring.
Comparison of contention-based protocols for secondary access in TV whitespaces
Richard MacKenzie (BT Research, United Kingdom); Keith Briggs - Presenting (BT Group, United Kingdom)
Exploitation of TV whitespace is now becoming a reality in many countries across the world. This allows for secondary systems to gain opportunistic channel access to TV spectrum as long as they do not interfere with the primary users of this spectrum; mainly the TV broadcasters and PMSE devices. While primary systems are protected from interference from secondary systems, secondary systems themselves must be able to coexist with one another; however, the rules and etiquette methods to allow for this are still being developed. Contention based protocols using random backoff mechanisms are therefore attractive for early adopters of TVWS due to the ease of coexistence with other systems. In this paper the performances of the contention-based protocols in 802.11 and ECMA-392 are analysed and their suitability for various scenarios in TV whitespaces are evaluated. While the two protocols have similar backoff rules, there are slight differences which can cause significantly varying performance. In addition this paper describes how the backoff behaviour of both protocols can be compared and evaluated using Markov chains. A description of an extremely fast and efficient way to solve these often large and complex chains is also given, which can be of further benefit in solving more complicated scenarios. A straightforward comparison of the backoff mechanisms is demonstrated by using the seminal Markov chain model of Bianchi . Results show a comparison of the two types of contention based protocols for varying networks sizes. For the same parameter settings it can be seen that 802.11 is much more aggressive. As a result, a 802.11-type behaviour achieves better performance for a small network, making it better suited to use cases such as video distribution around the home, while ECMA-392-type behaviour achieves better performance for a larger network, making it better suited to use cases such as machine-to-machine. This paper also shows how the performance of these protocols can be greatly improved by switching between a small set of operating parameters as the system size changes. The results also highlight the fact that secondary systems must not be too aggressive in order to share the channel in a fair manner should it be sharing the channel with another secondary system. The more conservative behaviour of ECMA-392 seems better suited for this coexistence. Finally, results are shown which look at the collision behaviour of each protocol. When multiple stations from secondary systems are likely to transmit at the same time, the aggregate interference must still avoid interfering with the primary systems. The two protocols are again compared with this in mind, highlighting that for either protocol actions must be taken to ensure that the aggregate interference is not above the specified threshold. The solution to this problem could be a combination of expected MAC behaviour along with power control mechanisms.  G. Bianchi, "Performance analysis of the IEEE 802.11 distributed coordination function," IEEE J. Sel. Areas Commun., vol. 18, no.3, pp.535-547, Mar. 2000.
Technical innovations from EU FP7 project QoSMOS (Presentation Only)
Michael Fitch (BT Exact, United Kingdom)
Spectrum sharing is not a new concept, but what is new is the ability of wireless systems to intelligently find gaps in the usage and occupy them. A new paradigm is where licensed and unlicensed users share the spectrum. An early example is sharing of UHF TV bands. First, we present some use-cases for such sharing, which have been evaluated technically and commercially. These have varying degrees of mobility and QoS requirements. Then we present the QoSMOS architecture, which is designed to provide management of shared spectrum with mobility and QoS support. This comprises a combination of database and sensing mechanisms, both of which are technologies that are critical to the spectrum management process. A third critical technology is at the PHY layer, where we have to improve beyond OFDM in terms of adjacent channel leakage, in order to share spectrum effectively without causing interference to neighbouring signals. We will describe Filter Band Multiple Carrier (FBMC) modulation scheme as a promising candidate.
Interference Mitigation Techniques Using 2X4 MIMO in Cognitive Radio Networks (Presentation Only)
Pertti Alapuranen (xG Technology Inc., USA); Rick Rotondo (2163 Wembely place & xG Technology, USA)
While Dynamic Spectrum Access (DSA) is core to cognitive radio and network operations, extensive field trials and testing by the US ARMY Cognitive Radio Access Networks (C-RAN) have shown that advanced Interference Mitigation technology can significantly increase spectrum utilization, increase total network throughput and enhance spectrum utilization. A technical paper/presentation and live platform demonstration will detail how a combination of 2X4 MIMO, state of the art SDR/DSP hardware and advanced signal processing techniques can be used to radically increase the time a CR is able to "dwell" on an interference laden channel, increase link reliability and measurably increase spectrum utilization. This form of interference mitigation is completely implemented on the receive side of the radio, so no noise or additional interference is introduced in to channel or spectrum being used. This also makes it difficult adversaries trying to intentionally jam a network (that has implemented this technology) to gage the effectiveness of their jamming efforts. Implementation within a CR or SDR network has significant military and public safety implications. This technique has application in licensed, unlicensed and white spaces spectrum bands and is currently implemented on an OFDM wave form. The technology is being deployed to support both military and commercial networking trials. Data from these deployments will be shared to the extent allowed by the customer. The presentation can be supported by live, instrumented demonstrations conducted on site at the Forum to show the effectiveness of this technique by the engineers who designed and implemented this technology.
Session 4.1 - SDR Architecture and Components
Chair: Manuel Uhm (Coherent Logix, USA)
14:30 - 16:00 (Netherlands I)
Comparing Baseband Architectures for 4G: The Necessity of Implementation Flexibility (Presentation Only)
Manuel Uhm (Coherent Logix, USA)
LTE is another step forward towards the harmonization of a global standard for commercial wireless communications. However, there are still a wide range of implementation options including RF bandwidth, throughput, number of users, FDD vs TDD, MIMO, etc. As such, it is important to retain implementation flexibility to address all the variants in a cost-effective and development-efficient manner. The most common baseband architectures today for mobile infrastructure reflect this need by doing some or all of the PHY on reprogrammable or reconfigurable devices. This presentation will contrast and compare these architectures including ASIC/FPGA, DSP/FPGA and massively parallel processors/FPGA. They will be compared on their technical merits, including scalability from picocell to macrocell, flexibility to support the breadth of deployment scenarios, power consumption for thermal management and reduced OPEX, and development methodology for time-to-market and ease-of-use.
A Simulation-Based Approach for Performance Evaluation of SDR Baseband Architectures *Top Paper*
Anthony Barreteau - Presenting (University of Nantes, France); Sebastien Le Nours (University of Nantes, France); Olivier Pasquier (University of Nantes, France)
Current trends in the design of radio communication systems consist in offering mobile terminals able to easily roam among heterogeneous networks like cellular, wireless local and metropolitan area networks. The purpose is to increase data rate and to propose access to a wide variety of services anytime and anywhere with a single device. This assumption leads to the well known cognitive radio (CR) and software defined radio (SDR) concepts introduced by Joseph Mitola in 2000. These concepts aim at defining flexible modem able to support a wide variety of protocols and the different configurations related to each protocol. Currently, parallel architectures are adopted in order to fully meet the functional requirements related to the protocols to implement and to the high flexibility needed. Such architectures are designed under real-time, power consumption, and cost constraints. In this context, one of the many challenges of mobile terminal designer is performance evaluation of candidate architectures early in the development process in order to minimize design errors and time-to-market delays. Due to increasing complexity, it has become mandatory to efficiently capture requirements of future flexible mobile terminals in order to evaluate and compare the performance of different architectures. In this paper, we present a simulation-based approach for performance evaluation of flexible baseband architectures. The proposed approach makes possible to model architectures implementing various protocols and their related management. Models can then be simulated to provide performance evaluation of studied architectures. The SystemC language is used to define executable models of architectures. Considered level of abstraction facilitates the evaluation of different configurations. The originality of this approach comes from the possibility to define executable models of reconfigurable architectures. The benefits of this approach are highlighted through the study of an architecture designed to implement physical layers of the protocols UTRA and Wi-Fi. Simulation results related to different configurations of these two protocols will be presented in the final paper. Simulation results make possible to observe evolution of the usage of processing resources according to different protocol operating modes. Achieved simulation time is fast enough to allow efficient exploration of the design space.
Analog-to-digital conversion - the bottleneck for Software Defined Radio frontends
Gerald Ulbricht (Fraunhofer Institute for Integrated Circuits, Germany)
An increasing number of radio access technologies and frequency bands for mobile communications present a major challenge for the equipment manufacturers. Future base stations have to handle GSM (Global System for Mobile Communications) with EDGE (Enhanced Datarates for GSM Evolution), UMTS (Universal Mobile Telecommunications System) with HSPA (High Speed Packet Access) and LTE (Long Term Evolution), future handsets additionally W-LAN (Wireless Local Area Network), NFC (Near Field Communications), Bluetooth, UWB (Ultra Wide Band)or GPS (Global Positioning System) in a frequency range between roughly 800 and 3000 MHz. Therefore, Software Defined Radio is considered the most attractive technology to meet the multi-standard and multi-band challenge for future radios. There are several architectures of RF frontends for multi-standard and multi-band radios. It is now 20 years since J. Mitola III coined the term Software Radio in 1992 and with that the vision of a radio, only defined by software . The idea behind is to abstain from an RF frontend and do everything in software. Of course, some RF components like antenna, LNA (Low Noise Amplifier), PA (Power Amplifier) and anti-aliasing filter will be necessary in most instances. However, there are no mixers or band filters which are required in conventional RF frontends. The determining component of a Software Radio receiver is the analog-to-digital converter (ADC). Since there are no frequency selective components in the frontend, all interferers reach the ADC without any attenuation. Svensson pointed out that the transmit signal of a GSM terminal can reach a power of -3.5 dBm at the antenna of a second terminal 2 m away . A dynamic range of at least 110 dB is required in order to not decrease the sensitivity of that terminal. In addition to the dynamic range requirement, the consumed power of an ADC with more than 6 GHz sampling rate and the desired dynamic range would be not acceptable . For multi-band application up to 3 GHz, direct sampling seems not to be feasible for the near future. However, Software Radios are already available for HF receivers with a performance comparable t a high performance conventional architecture . Several technologies and techniques have been developed to increase the dynamic range of the analog-to-digital conversion in order to face the challenges of future Software Defined Radios. This presentation will give an overview of the state of the art of analog-to-digital converters and dynamic range enhancement techniques like parallel converter bank, -conversion or feed-forward interference cancellation.  J. Mitola, Software radios-survey, critical evaluation and future directions, National Telesystems Conference NTC-92, 1992, S. 13/15-13/23  C. Svensson, The blocker challenge when implementing software defined radio receiver RF frontends. Analog Integrated Circuits and Signal Processing 64, 2010, Nr. 2, S. 81-89  K. H. Lundberg, High-Speed Analog-to-Digital Converter Survey, 2005, unpublished  N. C. Davies, A High Performance HF Software Radio, 8th International Conference on HF Radio Systems and Techniques, 2000, pp. 249-56.  P. T. Anderson, An (almost) all-digital HF communication receiver, RF Design, May 1999, 56-64
Heterogeneous Multi-Core Architecture for SDR Applications (Presentation Only)
Tal Kaitz (ASOCS ltd., Israel); Gaby Guri (ASOCS, Israel)
This paper describes a novel signal processing approach based on a heterogeneous multi-core architecture. This architecture, termed ModemX, is at the heart of ASOCS MP100 SoC and MG101 and MT-101 core IPs. ModemX is optimized for the implementation of wireless signal processing algorithms. It has been field proven in WLAN, cellular, digital TV, and proprietary aero-space systems. The architecture facilitates true SDR operation, where a single baseband processor implements a variety of air interface technologies and waveforms. (e.g OFDM, GMSK, WCDMA TD-SCDMA). True concurrent operation is possible where multiple waveforms are operated simultaneously. Moreover, new waveforms may be loaded without influencing the currently active set of waveforms. ModemX is based on a set of domain specific processing core types. Each core type is designed to effectively perform a small set of operations. This results in low area and low power consumption, competitive with dedicated H/W designs. Thus it is an ideal solution for mobile devices. On the other hand, the inherent scalability makes the architecture suitable for wireless infrastructure applications. The paper provides an overview of the architecture, processing elements, data-flow and memory arrangement. Several application examples are provided.
A System Architecture for Real-time Multi-Path MIMO Fading Channel Emulation
Elliot Briggs - Presenting (Texas Tech University, USA); Tanja Karp (Texas Tech University, USA); Brian Nutter (Texas Tech University, USA); Dan McLane (Innovative Integration, Inc., USA)
Creating a flexible, programmable multi-path fading channel emulator in hardware presents many design and implementation challenges. Past work has focused on creating a stochastic Jakes process generator as well as hardware efficient implementations of arbitrary upsampling. Significant advances in the design of the arbitrary ratio upsampler have been made, which has greatly reduced the hardware complexity and increased the system's performance, allowing the design to support MIMO emulation for 2 transmit antennas in a single FPGA device. Also building on previous work, the Kronecker model is introduced, allowing the user to vary the spatial correlation features in the emulated channel. This paper will quickly summarize the theoretical aspect of MIMO channel emulation. The main focus will be given to architectural and implementation details, following the system design process from end to end. A high level of attention will be given to multi-rate signal processing design aspects that minimize computational complexity. The results section highlights metrics from both simulation and FPGA hardware integration.
Session 5.1 - SDR Standards / Verification
Chair: Tom Rittenbach (CERDEC US Army, USA)
16:15-18:00 (Netherlands I)
Nowadays, the usage of tiger teams are basically restricted to security on the web services, provided by banks, insurance companies, etc. The paper demonstrate that the usage of these kind of very specialized teams can be applied to check the security of an SDR terminal. Further on this, the paper suggest the idea of how these teams can and their philosophy, can be applied to other stages of the product lifecycle. The paper explore the five W's of this approach, showing what are the teams, why are they necessary, where can be applied, when can be applied and who can apply it. Finally, the paper explore the How can these techniques can be applied.
- WINNF International SCA Standards Coordination Model, Catalyst for Lower Cost and Faster Capability Deployment (Presentation Only)
Mark R Turner (Harris Corporation, USA)
- The development and deployment of technologically advanced communications capabilities provided to the war-fighter needs to become increasingly more rapid and less costly across a multitude of military system and product solutions to ensure that the information flow on the battlefield keeps pace with the demands of the mission. The Software Communications Architecture (SCA) developed by the U.S. Department of Defense (DoD) provides a solid foundation for software high level reusability through standardization of a layered architectural framework providing separation between the underlying software infra-structure referred to as the Operating Environment (OE) with Waveform Applications through defined Applications Programmer Interfaces (APIs). Component Based Design (CBD) is the underlying technology of the SCA which also drives software reusability at the more granular software component level. The Wireless Innovation Forum SCA Committee has developed a Coordination Model for International SCA Standards providing the basis for harmonization among a suite of existing and emerging SCA based SDR specifications. The Coordination Model is intended to help leverage the significant investment of Governments, Industry and Academia via substantive economies of scale derived from a larger market base for SCA technologies, thereby providing benefit to the full spectrum of stakeholders. This presentation will explore another potential value proposition of the Coordination Model to further reduce software development cost and facilitate time-to-market savings through the application of Software Product Line and other related techniques. A Software Product Line (SPL) is defined as a set of software-intensive systems that share a common, managed set of features satisfying the specific needs of a particular market segment or mission and that are developed from a common set of core assets in a prescribed way. A harmonized set of SCA standards and specifications can facilitate the use of an SPL software development paradigm, broadly leveraging a highly reusable code base in an effective manner across multiple domains, systems, products and individual releases. In addition, SPL techniques when integrated with automated testing methodologies have the potential to significantly reduce the scale and time of rigorous testing cycles that ensure military SDR product compliance and reliability. Conclusions and recommendations will be provided from this analysis and evaluation.
5W's on Tiger Teams (Presentation Only)
Rafael Aguado (Global SDR, Spain)
Open Software and Hardware in SDR: How to accelerate growth of SDR (Presentation Only)
One of the most well known technologies with exponential growth is the Internet. One of the most important reasons for its explode is the wide availability of open-source Internet software. SDR has been growing fast during last 20 years, but its hard to name it "explosion". We will discuss why it is so important to have open technology for exponential growth and how to apply this idea to SDR. As a complex mix of hardware and software, SDR faces unique challenges and require a special care. We will also discuss a real-life example of how open-source allowed us to build a complete low-cost GSM base station with a ridiculously small team and short time. If time permits, we'll discuss peculiarities of doing business with open software and hardware in SDR. And what challenges pave this road.
Alexander Chemeris (Fairwaves LLC, Russia)
Meeting today's demands for Validating, Verifying and Certifying complex SDR Applications (Presentation Only)
Ken Dingman (Harris Corp, USA)
As the demands for battlefield communications continue to increase the complexity of the waveform applications employed to meet these demands grows in relationship. With the increased complexity of the solution comes the challenging problem of validating, verifying and certifying those solutions. An additional aspect of the problem is the rate of change being driven by the fielding of new technologies and the ability of certification organizations to maintain pace with it. Approaches to validation differ depending on the completeness of the user expectations and requirements of the application being developed. In any case it's imperative to understand the operational needs and time to market requirements to ensure the timely completion of the right functionality to meet the user expectations. This presentation will examine approaches we have used to validate the operational and time-to-market requirements for networking and narrowband waveforms. Verification of waveform applications and wideband networking WFs in particular is very challenging due to the dynamic operational environment the WF can execute in as a result of changing channel conditions and the movement of users in and out of a network and other external factors. This presentation will examine the innovative approaches to verification that have been undertaken in order to address these challenges. The path to certification can lead in different directions depending on a number of factors, including a standards maturity. The presentation examines factors that impact the approach to certification, lessons learned from numerous certification activities and proposes strategies to minimize cost and time-to-market impacts while protecting a company's intellectual property.