SDR-WInnComm Europe 2012 Papers and Presentations
27-29 June 2012
Brussels, Belgium

Comprehensive downloads:

• Keynote Presentations
• Papers

Presentation Abstracts:

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Tutorial 1.1  A Rapid Graphical Programming Approach to SDR Design & Prototyping with LabVIEW and the Universal Software Radio Peripheral
Filip Langenaken (National Instruments, Belgium)

The Universal Software Radio Peripheral (USRP) has proven a popular hardware platform for host-based software defined radio prototyping with GNURadio. While the approach is popular, the learning curve associated with Linux, GNURadio, Python, and C++ can be challenging for some potential users. To improve ease-of-use and enable the platform for a broader set of users, National Instruments has recently released support for the USRP hardware to Microsoft Windows and the LabVIEW graphical programming environment. This session will show how you can design and prototype communications algorithms with LabVIEW in Windows. Live demonstrations will show how you can define a custom communication protocol using LabVIEW-based graphical programming and establish a live digital link between two USRPs.

Tutorial 1.2 Using CREW: a federated platform for experimentally-supported research on cognitive networks and spectrum sensing
Stefan Bouckaert (Ghent University - IBBT, Belgium); Ingrid Moerman (Ghent University - IBBT, Belgium); Sofie Pollin (IMEC / UC Berkeley, USA); Asier Alonso (TECNALIA, Spain)

The aim of the FP7-call5 project CREW (Cognitive Radio Experimentation World) is to create an open federated testbed for the evaluation of cognitive radio and cognitive networking strategies. Experiments can be executed at 5 CREW test sites across Europe, located in Belgium, Germany (x2), Ireland and Slovenia, offering a diverse set of wireless technologies including heterogeneous ISM, heterogeneous licensed cellular, wireless sensor, and heterogeneous outdoor wireless networks. Since the start of the project in October 2010, the baseline testbeds of the testbed owners in the consortium have been extended with advanced sensing hardware developed by other partners in the consortium. Additionally, federation functionality such as a benchmarking framework allowing the comparison of different cognitive solutions, a common data format to store and share the experiments and experimental results, and mix-and-match interfaces that can be used to combine cognitive components from different partners were developed. Finally, a portal website was created (www.crew-project.eu/portal), which offers a single point of entry to experimenters, and provides information on the different facilities in the CREW testbed and how to access them. Early 2012, three additional partners joined the CREW project for the duration of one year after being selected as part of an open call for experimenters, to execute their experiments on top of the CREW testbed offered by the eight core partners of the consortium. While the former partners are using the current CREW testbed for the execution of their experiment, the other partners plan to improve the functionality offered by the federation in the coming months. =Tutorial program= In the first part of the tutorial, an overview of the federated CREW facility will be given, and the goal and use of selected CREW federation functionalities such as the common data format or the benchmarking framework will be explained. [ Presenter: Ingrid Moerman, IBBT. Duration: 30' ] The second and most important part will illustrate how the CREW facility can be used to evaluate cognitive radio/networking solutions, by presenting three concrete use cases that have been investigated using the CREW federation: -The CREW federation houses a broad range of spectrum sensing equipment, from off-the-shelf sensor nodes such as WiSpy devices, to specialised sensing engines that are custom-built by partners of the consortium. We demonstrate the technical background behind, the advantages of, and the experimentation possibilities enabled by integrating advanced sensing components in a cognitive networking testbed. [ Presenter: Sofie Pollin, imec. Duration: 20' ] -In past experiments performed by the CREW consortium, a common data format and benchmarking methodologies have been used to compare the different sensing devices that are present in the CREW consortium. Through this example, it will be explained to the audience how the benchmarking and common data aspects of the CREW federation contribute to making fair comparison of different cognitive solutions a possibility. Additionally, the results of the sensing device comparison experiment are briefly presented. [ Presenter: Stefan Bouckaert, IBBT. Duration: 20' ] -Testimonial from an open call partner. Tecnalia is one of the three partners that was accepted as part of the first open call for experimenters. In this talk, it will be discussed how CREW will be used to carry out an experiment focussing on the assessment of benefits of optimized linear collaborative multiband spectrum sensing in cognitive radio networks. [ Presenter: Asier Alonso Muñoz, TECNALIA-Telecom. Duration: 20' ] Before finishing with a Q&A, in a final part of the tutorial, we will show how the audience can learn more about the CREW federation and/or access the federated testbed, by demonstrating the use of the federated portal. Furthermore, we will share preliminary information on the second open call, which allows selected experimenters to become part of the CREW project and to get funded for executing their cognitive radio and cognitive networking experiments. [ Presenter: Ingrid Moerman, IBBT. Duration: 30' ] For the audience of the conference, this tutorial provides the opportunity to learn about the CREW project and about the existing possibilities of experimental research related to cognitive radio and cognitive networks in general. For the members of the CREW consortium, it is an interesting opportunity to meet the cognitive radio and cognitive networking experimenter community, whose comments and questions will help to shape the future of the CREW federation in a demand-driven way. =The presenters= Ingrid Moerman is a professor at Ghent University since October 2000. In 2006 she joined IBBT, where she is coordinating several interdisciplinary research projects, including the FP7-CREW project. She is currently leading the research and education on mobile & wireless communication networks within the 'Internet Based Communication Networks and services (IBCN)' research group, one of the research groups of IBBT. Her team has about 25 researchers. Stefan Bouckaert received his M.Sc. and Ph.D. degrees in electro-technical engineering from Ghent University, Belgium, in 2005 and 2010, respectively. He is currently a post-doctoral researcher at IBBT-IBCN, where he is mainly involved in the CREW project, working on the topics of experimentally-supported research and benchmarking. In January 2012, he became also responsible for the business development of the IBBT iLab.t research centre (http://ilabt.ibbt.be). Sofie Pollin received a degree in electrical engineering in 2002 and a Ph.D. degree in 2006 (with honors) from the Katholieke Universiteit Leuven, Belgium. Since October 2002 she has been a researcher at the Wireless Research group of imec. In the summer of 2004 she was a visiting scholar at National Semiconductor, Santa Clara, California. In the summer of 2005 she was a visitor at UC Berkeley. In 2006, she started as a post-doctoral researcher at UC Berkeley working on coexistence issues in wireless communication networks. Currently, she is a principal scientist at imec working on cognitive radio and software defined radio. Asier Alonso received a degree in electrical engineering from the University of Deusto in 2004, and also holds a master in computer architecture (University of Deusto 2008). Since 2005 he works as a full time researcher at the Telecom Unit of Tecnalia (before Robotiker), in the fields of Software Defined Radio, programmable logic, and signal processing.

Tutorial 1.3  Developing GNU Radio Signal Processing Blocks (no presentation available)
André Selva (Universidade Estadual de Campinas, Brazil); André L. G. Reis (Unicamp - State University of Campinas, Brazil); Karlo Lenzi (Universidade Estadual de Campinas, Brazil); Luís Meloni (Universidade Estadual de Campinas, Brazil); Silvio E. Barbin (University of Sao Paulo, Brazil)

GNU Radio is a popular toolkit for the development of SDR applications. Despite offering a large library of signal processing blocks, one may find useful to develop new blocks that fits exactly with the application requirements. Furthermore, complex applications, like Digital TV transceivers or LTE networks, for example, demand more complex digital signal processing blocks than the ones available in the GNU standard library. Thus, it is essential to know how to build custom blocks on GNU Radio if we desire to make full use of the GNU Radio features and Software Defined Radio platforms. This works aims to present an in-depth study of how to create new blocks in GNU Radio, clarifying dubious points generated from the lack of documentation available on the subject, which is based mainly on forums discussions and tutorials, and to serve as a future reference for new developers. To best understand this process and to cover all stages of development involved in creating blocks, we will present an step-by-step of how to build a byte interleaver, commonly used in wireless communication systems, such as WiMAX, LTE and DTV.

Chair: Vincent J Kovarik, Jr (Prismtech, USA)

Spectrum Sensing in the Vehicular Environment: An Overview of the Requirements *Top Paper* (paper) (presentation)
Haris Kremo - Presenting (Toyota InfoTechnology Center, Japan);  Rama K Vuyyuru (Toyota Info Technology Center, USA); Onur Altintas (Toyota InfoTechnology Center, Japan)

This paper overviews the challenges related to spectrum sensing in the vehicular environment, with emphasis on sensing in the TV licensed band. In the vehicular environment the cognitive radio can help to: 1) satisfy capacity demand for Intelligent Transportation Systems (ITS) applications; and 2) offload time insensitive applications from the ITS dedicated spectrum. However, neither sensing, nor geolocation database lookup alone can provide sufficient incumbent protection. Collaboration among the sensors to take advantage of spatial diversity is difficult due to the rapidly changing network topology. Nevertheless, mobility provides the opportunity to use time diversity at each sensor. We also discuss the influence of sensing subsystem design on the vehicular cognitive network medium access (MAC) sublayer. Whenever applicable, we compare sensing requirements for vehicular cognitive networks to the requirements provided in the IEEE 802.22 standard.

On the Performance Assessment of Heuristically-driven Linear Collaborative Spectrum Sensing within the FP7-ICT CREW Project  (Presentation Only - not available)
Asier Alonso (TECNALIA, Spain); Javier Del Ser (TECNALIA, Spain); Sergio Gil-Lopez (TECNALIA, Spain)

Spectrum sensing and decision are essential tasks of any cognitive radio system. As such, many different schemes have been devised so far in order to perform these task in the most accurate and reliable way, which can be a priori classified as: 1) conventional non-collaborative spectrum sensing, where a decision is taken at every cognitive node of the network in isolation; 2) collaborative spectrum sensing, where the spectral measurements registered by different nodes are combined - either in a centralized or distributed fashion - so as to produce a decision with higher reliability than the case where the decision is taken based on a single measurement (see rightmost plot in Figure 1). As for the latter, a number of collaborative spectrum sensing techniques pre-process the spectral measurements of every compounding sensing node of the network so as to produce a binary (hard) local decision on their occupancy, followed by a hard-decision fusion approach (e.g. OR, AND) that generates the final spectral occupancy metric. Technical advantages of these hard-decision based techniques lie on their simplicity for their implementation in conventional digital hardware. However, as was stated in the theory of evidence developed by Arthur P. Dempster and Glenn Shafer [1], binary local decisions can be easily outperformed, in terms of credibility and reliability when applied to outcomes of a same event, by soft fusion techniques where the unprocessed outcomes of the said event are input to a unique soft test. This interesting result motivates the upsurge of soft-decision based fusion techniques applied to spectrum sensing for cognitive radios. Among the broad portfolio of such combining approaches, in this work we have concentrated on the so-called linear statistics combination, which will be hereafter denoted as LSC [2]. LSC hinges on linearly combining the unprocessed spectrum measurements captured by cognitive radio nodes by means of a set of configurable coefficients, based on whose result a decision is taken. When the LSC is applied at each compounding band of a broad bandwidth, the resulting scheme is rather coined as multiband LSC. The values of such coefficients are usually set equal to each other in the conventional implementation of the LSC approach. However, as explained by the authors in [3], collaborative multiband LSC spectrum sensing can be optimized in terms of the achievable throughput over such a band by making use of evolutionary optimization strategies. Taking into account this state of art, this work gravitates on assessing the benefits of optimized linear collaborative multiband spectrum sensing in cognitive radio networks with respect to its non-optimized counterpart. Four specific goals stem further from this general objective: To incorporate the LSC decision scheme as well as its heuristic optimization framework recently introduced in [3] in a real testbed. To benchmark hard-decided collaborative spectrum sensing techniques against genetically-optimized and nonoptimized LSC approaches. To quantize the performance gains entailed by the application of Harmony Search (HS, see [5]) heuristics to the optimization of the LSC coefficients under a maximumthroughput criterion. To investigate and implement the data format, mechanisms and access procedures through which the sensed information is stored in a shared database and thus made network-wide available. From a general perspective, our technical contribution is twofold: on the one hand, HS heuristics are applied for the first time to the optimization of the linear coefficients involved in collaborative spectrum sensing. As such, this algorithm inspires from the improvisation process of musicians, i.e. the process by which such musicians (who may have never played together before) refine - through variation and check - their individually improvised notes resulting in an aesthetic harmony played by the entirety of musicians in the orchestra. Due to its outperforming behavior over genetic approaches and its simplicity, HS has been so far applied to a number of applications and problems related to wireless communication networks, such as the Capacitated P-median Problem [6], multicast routing [7], multiuser detection [8], [9], distributed radio resource allocation [10] and OFDMA subcarrier power allocation [11]. To the knowledge of the authors, this is the first contribution in the literature dealing with HS for the optimization of collaborative spectrum sensing schemes, which is expected to outperform its genetic counterpart in terms of aggregate throughput and/or speed of convergence. On the other hand, heuristically-optimized collaborative spectrum sensing is put into practice through its implementation on the test beds compounding the open federated experimentation platform provided by the CREW (Cognitive Radio Experimentation World) project [4], funded by the EC under the 7th Framework Programme. Specifically, a multiband energy level sensing functionality capable of capturing, formatting and forwarding spectrum measurements to a database is developed so as to allow the fusion center to access all the sensed spectrum information, hence modelling the conventional allocation of exclusive radio resources devoted to the circulation of cognitive control information (leftmost diagram in Figure 1). We will outline the results and conclusions regarding the performance of the previously mentioned heuristic algorithms obtained in the various tests carried out within the CREW real testbed, along with a comparison study with hard-decided AND and OR combination strategies. see attached extended abstract for more detail

Performance Evaluation of a Spectrum-Sensing technique for LDACS and JTIDS Coexistence in L-Band (paper) (presentation)
Giulio Bartoli (University of Florence, Italy); Romano Fantacci (University of Florence, Italy); Dania Marabissi (Università di Firenze, Italy); Luigia Micciullo (University of Florence, Italy); Claudio Armani (SELEX Elsag, Italy); Roberto Merlo (SelexElsag spa, Italy)

This paper deals with a cognitive approach able to guarantee the coexistence of new data link for air-ground aeronautical communications LDACS and military JTIDS systems. Future LDACS shall coexist with current systems operating in the same frequency band for this reason coexistence issues must be carefully investigated. In particular JTIDS transmissions can affect the LDACS performance acting as disruptive impulse noise. JTIDS exploits frequency hopping to protect information, hence its interference on LDACS system cannot be foreseen and avoided. In addition the bandwidth of the two signals results to be completely overlapped in case of collision. The disruptive effects of JTIDS interference on LDACS can be mitigated if the collisions can be detected and hence suitable processing techniques can be activated. This paper proposes a method to detect the presence of JTIDS interference exploiting an energy detection spectrum sensing technique based on sliding windows. The performance of the proposed method is presented in terms of missed detection probability of the JTIDS interference and error rate of the LDACS system showing a good behavior.

A Set of Methodologies for Heterogeneous Spectrum Sensing  (Presentation Only)
Wei Liu (IBBT, Belgium); Sofie Pollin (IMEC / UC Berkeley, USA); Peter Van Wesemael (IMEC, Belgium); Danny Finn (Dublin University, Trinity College & CTVR Telecomunications Research Centre, Ireland); Christoph Heller (EADS Innovation Works, Germany); Mikolaj Chwalisz (Technische Universität Berlin, Germany); Daniel Willkomm (Technische Universitaet Berlin, Germany); Nicola Michailow (Technische Universität Dresden, Germany); Zoltan Padrah (Jozef Stefan Institute, Slovenia); Ingrid Moerman (Ghent University - IBBT, Belgium); Stefan Bouckaert  (Ghent University - IBBT, Belgium)

Cognitive radio has received tremendous amount of attention in the academic world. As a key enabler for cognitive radio, the spectrum sensing technology faces many challenges. The real-life wireless communication often happens in a heterogeneous environment, hence, how to combine sensing results obtained with heterogeneous devices is one of the biggest challenges. In order to have a valid heterogeneous sensing system, many issues need to be , such as the calibration among heterogeneous devices, post processing for the obtained data in different formats, what is the most efficient way for combining data, and many other aspects. In this work we present a set of methodologies that have been derived in the scope of the CREW project to deal with some common issues encountered for heterogeneous sensing. The FP7 project CREW (www.crew-project.eu) targets the development of a federated testbed for cognitive radio systems by physically and virtually interconnecting radio equipment of the individual project partners. By combining the spectrum sensing devices from each project partner, we are able to form a sensing platform with many popular heterogeneous devices. These devices include dedicated integrated sensing hardware (imec sensing engine), USRP software-defined radios (SDRs), small, low power sensor nodes (TelosB), off-the-shelf, low cost USB spectrum analyzers (WiSpy) as well as high cost, high precision spectrum analyzers. The presentation will start with a series of heterogeneous and distributed sensing experiments that we performed as background information. The aim of those experiments was originally to compare the performance of different sensing devices. However, during those experiments we have gradually formed a system to properly process distributed data and calibrate heterogeneous devices. The derived methodologies are covered next. The main focuses here are the measurement we performed to compensate for the hardware heterogeneity, and the common data format we derived to overcome the software difference.Finally we also propose some principles we adopted to detect outliers in the heterogeneous distributed sensing experiment. This work is not about analyzing results from any particular heterogeneous sensing experiment, but rather to learn from all the experiments from a methodology point of view. It can serve as a reference for future work in heterogeneous sensing.

Session 6.1 - Cognitive Radio / Networks
Chair: Claudio Armani (SELEX Elsag, Italy)

Mapping Cognitive Radio System Scenarios into the TVWS Context *Top Paper* (paper) (presentation)
Per H. Lehne (Telenor Group Industrial Development, Norway); Richard MacKenzie (BT Research, United Kingdom); Dominique Noguet (CEA LETI, France); Vincent Berg (CEA LETI, France); Ole Grøndalen (Telenor, Norway)
Cognitive Radio has been one of the key research topics in the wireless community for about 10 years. The digital switch-over in the TV bands provides opportunities for Cognitive Radio Systems (CRS) to operate in the UHF spectrum under incumbent protection restrictions. Regulation bodies, in particular the FCC and Ofcom in the UK, have specified parameters under which CRS shall operate. In this paper we analyze key scenarios for CRS stemming from the QoSMOS project. Then, we analyze how these scenarios can be mapped into the TV whitespace (TVWS) context by considering link budget computation based on FCC and Ofcom transmit power recommendations as well as statistical propagation models for the UHF band. We eventually conclude on the most promising scenarios in the context of the TVWS usage. Identifying scenarios at an early stage in system development is important as this can keep further development aligned, working with a common goal in mind. If a CRS is going to be attractive for most actors in the wireless industry, it has to provide a significant benefit compared to what is possible with today's and tomorrow's mainstream wireless technology. The scenarios identified in this paper are being used by the QoSMOS project to help guide the development of tools and techniques to bring these cognitive radio concepts closer to real-world systems. Three top criteria have been defined in order to select feasible deployment scenarios for a CRS providing both managed QoS and high mobility: "Benefit from CRS technology", "Benefit for actors", and "Managed QoS and mobility". Further, seven additional criteria have been used for targeting the most interesting and promising scenarios for business case studies. The three resulting scenarios are "Cognitive femtocell", "Cellular extension in WS" and "Cognitive ad hoc network". The analysis of how the scenarios apply to the specific case of TVWS (470-790 MHz) shows that indoor and indoor-to-outdoor short range communications is viable for the cognitive femtocell and cognitive ad hoc scenarios. Cellular extension usage is only viable for short range outdoor cells due to the secondary transmit power limitations on mobile devices imposed by regulations. On the other hand, fixed long range access can be achieved with ranges up to 8 km in suburban areas. From the FCC and Ofcom figures and link budget calculation, it can be concluded that indoor WLAN-like scenarios and fixed broadband access are the most realistic scenarios among those considered by the QoSMOS project. Extension to cellular networks is also possible, but shall focus on dense areas where cells of 1.5km are viable from a market point of view. This is typically the case where cellular system offload is required.

Opportunities of Cognitive Radio Technologies for advanced Regulatory Regimes  (Presentation Only)  
Eiman Mohyeldin (Nokia Siemens Networks, Germany); Maximilian Riegel (NSN, Finland) 
The rapidly increasing Internet/data traffic will require additional spectrum to support the higher traffic and capacity. it is expected that new spectrum for mobile broadband will be identified in WRC2016, however from today's perspectives this will not meet the predicted demand for 2020. Thus new technologies with increased spectral efficiency and the has the potential to use the radio spectrum resources much more dynamically and efficiently will be needed. In this context, cognitive radio techniques offer improved efficiency and additional flexibility to the spectrum use. In the current studies related to Cognitive Radio, different standardization, regulation and research institutes, have identified important aspects related to the use of Cognitive Radio, cognitive technologies could be an enabler for different strategy of spectrum sharing on more dynamic basis, thus providing increased spectral efficiency of existing spectrum and mitigate the problem of congestion (e.g. capacity gain). Cognitive radio with its technologies, such as: • Sensing • Geo-location • Beacon and its possibility to be implemented in: • frequency bands that have multiple radiocommunication service allocations ( shared and opportunistic access) is anticipated to be the most suitable technology in shared spectrum access based on dynamic spectrum access. Different approaches for shared spectrum access are existing in some of the frequency bands, however they are being prompted for license exempt( e.g. TV whites space). But for mobile broadband there is need for faster access to spectrum while maintaining certain grad of quality of services. Based on these requirements ( faster access and QoS) , regulatory approaches and licensing regimes for shared spectrum access have been under study and analyses by industry and regulatory bodies. Two approaches are envisaged: • Authorized shared access (ASA) • Licensed shared access (LSA) The two approaches have common features: • Unlock the band used by incumbent ( primary user of the band) for new users • ensure predictable quality of service for all right holders • sharing agreements/ conditions among incumbent and the new users The implementation of shared spectrum access under ASA or LSA will make advantages of cognitive radio technologies. More detailed analysis and discussion on ASA/LSA and the best suited cognitive radio techniques for shared spectrum access (ASA/ LSA) will be explored in the final contribution.

 

Cognitive multi-mode and multi-standard base stations: architecture and system analysis  (paper) (presentation)
Franco Mazzenga (Università di Roma Tor Vergata, Italy); Claudio Armani (SELEX Elsag, Italy); Alessandro Neri - Presenting (University of ROMA TRE, Italy); Romeo Giuliano (Università di Roma Tor Vergata, RadioLabs, Italy)

Each wireless technology/standard has been optimized to provide a specific set of services, in accordance to technical and economic aspects. The possibility of changing the communication technology allows the introduction of more flexible management of transmitted power and radio resources in accordance to the offered traffic, services and QoS. The adoption of multi-mode base stations (BSs) offers an additional degree of freedom for efficient usage of the radio resources. One or more radio access technologies can be activated in the single cell area in accordance to offered traffic load and service requests. Users can be distributed among the different technologies. Multi-mode BSs open new and very interesting scenarios for the development and deployment of innovative mobile access networks. In this paper we consider new access network architecture based on multi-mode BSs even including possible cooperation among different service providers. Capacity improvement due to spectrum sharing is known and shall be encouraged. It is well known that radio access systems providing spot-like coverage can be used to off-load primary mobile radio systems extending over the entire cell area. Practical examples are provided by Wi-Fi and WCDMA and femtocells. Multi-mode BSs facilitate the implementation of the off-loading concept. Achievable improvements in the case of LTE off loading UMTS are analyzed in this paper.

Interference and Coexistence in Recovery Communications after Large Incidents  (Presentation Only)
Daniel Devasirvatham (SAIC, USA)

The awesome power of large natural disasters or man-made incidents could compromise civilian and emergency communications over a large area. Traditional techniques concentrate on building stronger terrestrial infrastructure to withstand such events; but these are often overcome. Satellites are used as back-up or for emergency communications recovery. However, these may not have sufficient spatial capacity to serve a large concentrated user base, and users may not have sufficient terminals to use them or be conversant with their use in an emergency. Consequently, command, communications, control, and situation awareness are compromised. An integrated methodology for communications recovery was proposed in [1]. This paper described a phased approach, starting with satellite communications if necessary, and then transitioning to airborne relays. These would be gradually brought lower down to quickly substitute infrastructure and to re-establish ground communications while increasing spatial capacity. The Satcom SIG and the Public Safety SIG have a joint project to develop a Hybrid Architecture for this purpose. The Federal Communications Commission (FCC) also organized a workshop on Deployable Aerial Communications in October 2011, in which the author was an invited speaker. A One-day workshop will be held by the Forum in March 2012. However, several issues need to be addressed for this to be implemented in a practical and user friendly manner. Some of these are 1) Identifying and minimizing interference from the elevated relays to existing and still operational ground infrastructure, 2) criteria to determine acceptable interference under the circumstances, so that impact on existing operations is minimized, 3) Ad-hoc/peer-to-peer mesh networking between relay craft and connection to satcom to extend the reach of the rescue relay system. This can be greatly facilitated by software defined radios with cognitive capability. These topics are also extremely important for regulatory reasons, since there will be no opportunity to do formal planning and regulatory authorization of recovery methods in the aftermath of a major incident that occupies a large area. Hence a well understood, formally validated and pre-approved methodology needs to exist so that it can be implemented rapidly after a disaster. This full length paper will analyze some of the engineering issues such as interference, and other challenges to the proposed solutions. Formal validation of this approach could result in the development of standards regulations and operational protocols that can ensure a safe architecture and operating parameters for recovery communications. [1] Devasirvatham, D. M.: "Communications Recovery after Large Incidents", WInComm-Europe, paper No. 1569440323, Brussels, pp 61-65, July 2011.

Energy Efficiency and Fairness in Cognitive Radio Networks: a Game Theoretic Algorithm  (Presentation Only)
Renato Pucci - Presenting (CNIT - University of Florence, Italy); Enrico Del Re (University of Florence, Italy); Luca Simone Ronga (CNIT, Italy); Claudio Armani - Presenting (SELEX Elsag, Italy); Matteo Coen Tirelli (SELEX Communications, Italy)

Cognitive Radio provides a paradigm to enable a more performing use of spectrum resources. Several challenging issues are still to be solved in order to fully exploit the CR potentials. One of these is the development of efficient distributed power allocation methods to be performed by the independent decisional entities of the network, consisting in primary and secondary users. Formulated as an optimization problem, the resource allocation problem between secondary users and primary users can be modelled and investigated with the Game Theory, and in particular S-Modular Games, since they provide useful tools for the definition of multi objective distributed decisional algorithms in the context of radio communications. In this work, we provide an energy efficient game theoretic framework to solve the resource allocation problem in a cognitive network, wherein primary and secondary users coexist. We consider a distributed game-theoretic approach to obtain a power allocation method that maximize the energy efficiency of each user, within the coexistence of primary and secondary users. The proposed method take into account throughput fairness among secondary users. The non-cooperative game is modelled as game with one primary user and N secondary users, namely the players of the game, operating on one radio resource. Note that the proposed scheme can be extended to include more than one primary user and M available radio resources, i.e. different channels or subcarriers of the same multi-carrier channel. Each user is characterized by a transmitter site and a receiver site, thus, each communicating couple consists of a dedicated sender and receiver. In the most general context we consider the transmitters and the receivers positions completely independent the ones from the others. The utility function that each user maximize has an energy efficient formulation and it includes a pricing terms in order to let the game be as fair as possible for all the users. Indeed, secondary users are discouraged to transmit at high power levels, since they are charged on the base of the interference they generate, thanks to the introduction of a pricing function inside of the utility function. The utility function includes also a stochastic modelling of the number of bits that are successfully received for each unit of energy drained from the battery for the transmission. On the other hand, a smart parameterization of the pricing function let the function be adaptable to every kind of network configuration. Simulation results demonstrate the convergence of the proposed system for a random number of users in the cognitive network. In order to obtain a qualitative evaluation of the proposed game, we decide to compare its performance with both AN Energy Efficient version of the Iterative Water Filling (EEIWF) and an optimal centralized heuristic power allocation system, like Simulated Annealing (SA). Simulation results show clearly that the algorithm based on game theory obtains better performance than EEIWF and converges to the same SINR values obtained from the heuristic optimization method. However, unlike these, the proposed game results to be the most energy efficient, also for a large number of considered users.

Improving efficiency of Genetic Algorithm based Optimizer for Cognitive Radio (presentation)
Ajay Sharma (Defence Electronics Applications Laboratory, India); Gaurav Kapur (Defence Electronics Applications Laboratory, India); Vipin Kaushik (Defence Electronics Applications Laboratory, India); Lal Mangal (Defence Electronics Applications Laboratory, India); Ramesh Agarwal (Defence Electronics Applications Laboratory, India)

An important function of cognitive radio is to adapt its configuration to optimize its resources and performance. Recent researches on cognitive radio have proposed Genetic Algorithm (GA) based multi-objective optimization for this purpose. As the optimization involves GA processing, which is a time consuming activity even using best available hardware, it is difficult to get real time performance. Also, to obtain more accurate results from GA, the population size needs to be increased, which in turn takes more time to converge. For applications that require immediate response from system like in tactical radio environments, there is the need to improve its efficiency in terms of time. The paper proposes a methodology to modify the way GA processing results are used, so that cognitive radio responds faster.

Session 6.2 - SDR Implementations 2

Chair: Gerd H. Ascheid (RWTH Aachen University, Germany

Baseband Signal Processing Framework for the OsmocomBB GSM Protocol Stack *Top Paper* (paper) (presentation)
Harald Kröll - Presenting (ETH Zurich, Switzerland); Christian Benkeser (ETH Zurich, Switzerland); Stefan Zwicky (ETH Zurich, Switzerland); Benjamin Weber (ETH Zurich, Switzerland), Qiuting Huang (ETH Zurich, Switzerland)

Recently, the open source community has discovered the GSM protocol as an interesting exploration area, mainly for security aspects. Among the various successful attempts of open source implementation of several parts of the GSM network, the community behind the Open Source Mobile Communication Baseband (OsmocomBB) project has implemented relatively complete versions of the physical layer (L1), the data-link layer (L2), and the GSM signaling protocol (L3) of the mobile station (MS) side, running partially on a host computer and partially on hardware of a MS. Unfortunately, hardware support for L1 is limited: reverse engineered legacy phones with modified firmware are mainly used for running OsmocomBB software. Access below the DSP application interface (API) can hardly be achieved, which limits the scope of new applications and implementations. Important tasks in digital baseband domain, such as channel equalization or decoding, are mostly implemented on the DSP, and therefore not accessible for further investigation. This deficiency restricts using OsmocomBB for (research) activities on the physical layer, which includes analog and digital front-end, baseband signal processing and L1 control functionality. The signal processing, hardware development and communication technology community has strong interest in an expandable baseband development framework with an interface to L2 and above of the GSM protocol stack. OsmocomBB's L1CTL protocol between L1 and L2 is well defined, but there is no development environment available in an ubiquitous scientific computing language such as MATLAB or GNU/Octave, which can be connected to L1CTL. A framework with an interface of this type would simplify the validation of the functionality of baseband implementations towards higher layers in a closed system without expensive measurement equipment. Baseband engineers could use OsmocomBB during the design process and during testing signal processing blocks that require interaction with L2/L3, e.g. cell search or incremental redundancy (IR) management (IR is specified for EGPRS, which is not part of OsmocomBB so far). Moreover, the open source community also would benefits from such a framework and interface, because it would enable them to extend their working areas towards the physical layer, e.g., developing receivers from scratch. In this contribution, a MATLAB based physical layer development framework with an appropriate interface to L2/L3 of OsmocomBB is presented. The framework contains digital baseband signal processing with corresponding L1 controller and time processing unit (TPU), as required for GSM. The different signal processing blocks are partitioned into so called primitive functions, which solve essential problems like signal filtering, symbol detection, parameter estimation, bit scrambling and decoding. The standard OsmocomBB interface between L1 and L2, called osmocon, uses a serial link with HDLC protocol to load the firmware into the phone's memory. Using L1CTL messages, this firmware communicates via osmocon with a Unix domain Socket as implemented on the OsmocomBB side for the connection to L2/L3 running on the host computer. As MATLAB does not directly support Unix domain sockets, an interface written in C is required for the socket communication. Having such an interface embedded in a MEX function, it can be called inside a MATLAB script. Conversely, the interface may execute MATLAB commands directly by means of MATLAB engine function calls. However, both MEX function calls and MATLAB engine function calls are blocking, which prohibits independent execution of the TPU and L1CTL protocol handling. Instead, the interface developed for the proposed physical layer development framework connects the Unix domain socket to MATLAB via memory mapped file. In order to prevent accidental overwriting of data in the memory, a handshake protocol has been implemented. The memory mapped file consists of entries for all required information, e.g. GSM counters, L1CTL message properties, payload, as well as necessary information for the handshake protocol. The messages of the L1CTL protocol are inspired from the GSM specifications (cf. 3GPP 44.004). They can be subdivided into request (REQ), confirm (CONF), and indication (IND) message types. The implemented framework dispatches L1CTL protocol messages arriving from the OsmocomBB interface, and calls corresponding primitive functions, which trigger the execution of one or more specific signal processing blocks. As timing is esssential in GSM, a TPU is implemented, which emulates the four GSM timebase counters. Primitive functions are called according to the counter states. For each call, the counters are increased by the number of symbols the corresponding primitive function processes, even though MATLAB cannot perform the signal processing in real-time. Also data-dependent events are triggered according to the counter states. The corresponding L1CTL messages are generated and transmitted to OsmocomBB. The functionality of the proposed physical layer development framework in combination with L2/L3 of OsmocomBB has been verified by performing the initial cell search procedure in GSM, including beacon carrier detection, synchronization, demodulation and decoding of system information. In order to feed the framework with real-world data, a test-setup has been developed that comprises of a GSM base station (BTS) emulator for transmitting a standard-compliant GSM beacon channel, and a receiver testbed with state-of-the-art RF transceiver connected to an FPGA. The BTS emulator has been realized with OpenBTS (an open source BTS software) and GNU radio software running on a computer, and a USRP board with antenna to transmit the signal over the air. At testbed-side, the received signal is down-converted, digitized and buffered, that the samples can be accessed via FPGA. Thus, the received samples are loaded into the proposed framework, where the beacon carrier is found, and synchronization in time and frequency is achieved. The system information broadcast on the beacon carrier is correctly extracted and propagated through OsmocomBB, and the physical layer framework with OsmocomBB achieves the GSM state 'camping on any cell'.

 

Implementing MATLAB Communications Models on the HyperX 100 Core Processor  (Presentation Only)
John Irza (Coherent Logix, USA)

 Many Software Defined Radio development efforts use MATLAB for modeling at the algorithm and system level. Conversion of MATLAB code into C code is typically done for simulation acceleration, IP portability, and to support a path to productization. Traditionally this results in a broken design flow because of manual re-writing of MATLAB into C. Further, the downstream C flow is often broken as well, since the C representation is re-written again to target specific hardware architectures. This paper will describe a design flow which provides an unbroken design and verification path from a MATLAB communications model to the HyperX many-core processor. This enables the engineer to develop a hardware agnostic solution in MATLAB while benefiting from a hardware implementation that be used, unchanged, either as simulation accelerator or as the final deployed product.

An Innovative SDR Architecture and a MANET with Simultaneous Multiple Channel Reception  (Presentation Only)
Moshe Miki Weiss - Presenting (RAFAEL - Advanced Defense Systems, Haifa, Israel); Michal Wermuth (Communication Industry & Rafael - Advanced Defense Systems LTD, Israel); Itzhak Fuchs (Defence & RAFAEL, Israel)

 Scalability and efficient, flexible spectrum utilization are among the difficult challenges of modern military Mobile Ad Hoc Networks (MANET), both for ground or airborne forces. Commonly, a large frequency range (e.g., UHF from 225-400 MHz) is allocated to a large military organization (Division, Corps etc) operating in a wide arena. In common MANET systems, the radio can receive only one channel at a time (per band, in a multiple band SDR); once the channel frequency has been set, the networking is carried on only among the members (Tanks, APCs, Aircrafts…) that are tuned to that channel, and the MAC algorithm is blind to all other channels. Although the frequency can be selected among many, once it has been chosen, it becomes unrelated to the networking operation. Thus, a MANET system with a collection of channels is in fact a collection of unconnected parallel MANET systems, with data rate limited by the bandwidth of a single channel. In every channel, a different MANET is established, and the participants of that MANET run distributed algorithms to decide how to divide the channel between them, commonly an adaptive TDMA MAC algorithm. In this scheme, a member is assigned either to a unit network (Company, battalion, A/C formation…) or a functional network (Operations, Intelligence, Fire support, Logistics...), where each of these networks is associated with a single frequency channel. However, during combat dynamics, units mix geographically; they merge, pass-through each other or split - members need also to communicate with members of other networks in their neighborhood, for Situation Awareness (SA), Fratricide and Collision Avoidance (FA, CA) etc. These message types have geographical vicinity context - Cross or Inter-channel networking is a paramount need. Accomplishing this need with a single channel receiver (per band) is difficult and inefficient - it is sometimes done with either a node time-sharing its network participation between an Intra-Unit network and a geographical Inter-Unit network, or by inter-channel gateways with multitude of multiple transceiver SDRs. Another approach is frequent reconfiguration of the network participation of a node - not only it causes delays and control overheads, it doesn't solves a member's need to concurrently participate in several networks. All these approaches are not scalable - 1) The time-sharing scheme results in a very low throughput for the Inter-Unit SA messages, since the data rate in a single channel network is inversely proportional to the number of members time-sharing it. Moreover, during the Inter-Unit time period, the entire allocated spectrum except a single channel is not used. 2) In the radio-gateways approach, the same information is re-transmitted again in all destination channels thus reducing capacity. Another property of military MANETs is a large asymmetry between transmission and reception - most members need to receive much more data than they transmit. This is typical for SA/CA messages, where a member periodically transmit its position, velocity vector and status to numerous (could be hundreds) other members. Another case is when few sensors transmit high rate data to numerous members in the area. It is shown that this asymmetry translates to network bottlenecks caused by the reception rather than the transmission capability of a SDR transceiver. All of the above challenges are solved when a node's SDR has many reception channels, ideally being able to simultaneously receive all the frequency channels in its allocated band. RAFAEL BNET family of SDRs, utilizing the latest technological advances of ultrafast (Giga-samples/sec), high dynamic range ADCs and ultrafast (Tera ops/sec) FPGAs, is a new generation of "Almost Ideal" SDRs, in which digitization is done close as possible to the Antenna. BNET SDR is not the traditional Super-Heterodyne; rather, it consists of a digital Channelizer, simultaneously processing hundreds of channels. In the MCR MANET architecture, the Modem functions are performed on all channels. A distributed, "two dimensional" F/TDMA MAC algorithm determines for each node at each time-slot in what channel to transmit. All received packets are available to the higher network layers, which process and filter them according to their destination. Hence, the MCR scheme breaks the usual "Channel = Network" relation; channels are assigned by the MAC to users and communication service types according to their link state and QOS requirements, in a manner transparent to the users. Networks are logical rather than physical, according to Multicast and Broadcast groups that are constructed by need-to-share needs. For Periodical (refreshing) Messages (PM) used for the SA and topology dissemination or control function, we show that message rate is almost linearly growing with the number M of channels allocated, as long as the easy condition M/N <<1 is met; (N being the total number of nodes in all channels). Furthermore, we show that MCR for PMs almost achieves the Shannon bound for a single 1-Channel UWB TDMA; (however, a UWB-TDMA is inappropriate for long range communication as it requires a long guard-time which consumes most of the short packet time, and a physically non-achievable high peak power). MCR MANET also readily facilitates low-delay, "Combat" Voice and high throughput sensor data (Video or Radar), where few sensors are disseminating their data to a wide area. While a node participates in the wide area PM MANET over several RF channels, in some other channels it continuously receives several high data rate sensors without conflicts. Other advantages of an MCR SDR are - 1) FH ECCM - only the transmitter has to hop. 2) Each SDR is an instantaneous WB Spectrum Analyzer, making it "Cognitive Ready". Summarizing, the combination of ultra-WB digitization and ultra-fast simultaneous processing of whole RF bands with 2 dimensional F/TDMA MAC algorithms - allows MCR SDRs to approach the Ideal "True SDR" vision with maximum flexibility for military tactical MANETs, and a 10 to 100fold times increase in reception throughput.

Software implementation of the IEEE 802.11a/p physical layer *Top Paper* (presentation) (paper)
Teo Cupaiuolo (STMicroelectronics, Italy); Daniele Lo Iacono (STMicroelectronics, Italy); Massimiliano Siti (STMicroelectronics, Italy); Marco Odoni (STMicroelectronics, Italy)

Software defined physical layer modems represent one of the main trends in communications and computing emerged in recent years. This is due on one hand to the need of supporting the requirements of modern communications systems in terms of seamless integration between different wireless technologies and multimedia convergence. On the other hand, programmable platforms are also beneficial as they allow consolidating methodologies, shortening development time and costs, extending products life-time. The drawback is that the complexity and power overhead of a pure computing fabric compared to a dedicated hardware can still represent a cost product developers are not willing to pay. This is particularly true for mobile terminals or in general for battery-powered devices. To become a concrete opportunity, baseband platforms should provide almost the same performance of custom designs while maintaining a certain degree of programmability. A good trade-off is represented by specific architectures integrating a proper mix of fine-grain general-purpose instructions and dedicated coarse-grain instructions wrapping custom hardware modules. This paper presents a software implementation of a dual-mode IEEE 802.11a/p receiver on the Block Processing Engine (BPE), a proprietary template platform specifically designed for baseband processing. The combination of a novel extended instruction set with multi-thread processing support allows satisfying the most demanding requirements of the 802.11a and 802.11p standards.

Designing and implementing 4G Cellular Modems on a heterogeneous multi-core architectures (presentation not available)
Paul Tindall (Cognovo, Ltd., United Kingdom)

This presentation describes the novel approach to the design and implementation of 4G Cellular modems running on a scalable multi-core architecture. It describes the system design methodology used to express concerns of Power Consumption, Memory Usage and Timing deadlines. These concerns are modeled to allow design exploration. Finally, the design is implemented to run on real silicon, where the design intention is visualised and validated. The presentation also describes the Cognovo Modem Compute Engine, a commercially available IP platform optimised for low power handheld wireless modems.

LTE PHY Layer Engineering
Slawomir Pietrzyk (IS-Wireless, Poland)

This tutorial provides a description of the LTE Layer 1 and E-UTRA nodes, namely eNB and UE, combining theory with the practical hands-on demonstrations. The demonstrations include generation and observation of the eNB and UE signals and are based on the state-of-the-art LTE PHY Lab, which is a comprehensive implementation of the 3GPP Release 8, 9 and 10 E-UTRA physical layer. Students are guided through the architecture of eNB and UE, and have the chance to learn the role of each processing block, as well as to generate Layer 1 waveforms corresponding to every physical channel. In addition to that, they evaluate the influence of such effects like uncompensated synchronization offsets. Observations are made either in the time domain (osciloscope function) or in the frequency domain (spectrum analyser function) so the students are getting prepared to work with real measurement tools in implementation or testing of the real equipment. The tutorial is ended by making suggestions on the possible test scenarios for real eNBs and UEs.

 

LTE Radio Network Planning

Slawomir Pietrzyk (IS-Wireless, Poland)

LTE radio interface (i.e., E-UTRA) is build around OFDMA, SC-FDMA and MIMO. This is a different set of radio transmission techniques than the one used in the previous 3GPP standards (such as GERAN or UTRAN). OFDMA and SC-FDMA allow to utilize the parallelism in the frequency domain and to manage the spectral resource with the high level of granularity. MIMO provides yet another domain, namely space. These schemes cause the radio planning process for LTE to be different from the previous standards. In this tutorial, we highlight the most important differences in the radio interface architecture, draw conclusions on how they impact the process of radio network planning and formulate a basic set of recommendations on how to deal with these differences.