A power and time efficient radio architecture for LDACS1 air-to-ground communication

L-band Digital Aeronautical Communication System (LDACS) is an emerging standard that aims at enhancing air traffic management by transitioning the traditional analog aeronautical communication systems to the superior and highly efficient digital domain. The standard places stringent requirements on the communication channels to allow them to coexist with critical L-band systems, requiring complex processing and filters in baseband. Approaches based on cognitive radio are also proposed since this allows tremendous increase in communication capacity and spectral efficiency. This requires high computational capability in airborne vehicles that can perform the complex filtering and masking, along with tasks associated with cognitive radio systems like spectrum sensing and baseband adaptation, while consuming very less power. This paper proposes a radio architecture based on new generation FPGAs that offers advanced capabilities like partial reconfiguration. The proposed architecture allows non-concurrent baseband modules to be dynamically loaded only when they are required, resulting in improved energy efficiency, without sacrificing performance. We evaluate the case of non-concurrent spectrum sensing logic and transmission filters on our cognitive radio platform based on Xilinx Zynq, and show that our approach results in 28.3% reduction in DSP utilisation leading to lower energy consumption at run-time

An Efficient Cluster-based Routing Protocol in Cognitive Radio Net-work

Cognitive Radio Networks (CRNs) are being studied intensively and gaining importance as spectrum is the heavily underutilized. CRN has the capability to exploit smartly the unutilized frequency spectrum. Recently, the research community started to work in the area of cognitive radio routing. In a flat topology, all nodes are of the same level and functionality, thus making it simple and efficient for smaller networks. However, when the network is large with sparse nodes, the routing information becomes more complex making cluster-based techniques really relevant to tackle such situations. In a cluster-based routing, all nodes in the network are dynamically organized into partitions called groups or clusters. In each cluster, a cluster head is chosen to help in the data transmission management and to maintain cluster membership information. This paper proposes a novel routing protocol for cognitive radio ad hoc networks (CRAHNs) based on clustering model which amends swiftly to the topological changes and establishes the routing efficiently. Our proposed approach is thoroughly evaluated through simulation study. The results state the suitability of the proposed protocol for cognitive radio ad hoc networks and demonstrate that it has better performance in terms of finding the source-destination route, reducing the amount of messages that are transmitted all over the network and minimizing the routing delay.Comment: International Conference on Advanced Communication Systems and Signal Processing (ICOSIP 2015), Nov 2015, TLEMCEN, Algeria. 201

Spectrum sharing security and attacks in CRNs: a review

Cognitive Radio plays a major part in communication technology by resolving the shortage of the spectrum through usage of dynamic spectrum access and artificial intelligence characteristics. The element of spectrum sharing in cognitive radio is a fundament al approach in utilising free channels. Cooperatively communicating cognitive radio devices use the common control channel of the cognitive radio medium access control to achieve spectrum sharing. Thus, the common control channel and consequently spectrum sharing security are vital to ensuring security in the subsequent data communication among cognitive radio nodes. In addition to well known security problems in wireless networks, cognitive radio networks introduce new classes of security threats and challenges, such as licensed user emulation attacks in spectrum sensing and misbehaviours in the common control channel transactions, which degrade the overall network operation and performance. This review paper briefly presents the known threats and attacks in wireless networks before it looks into the concept of cognitive radio and its main functionality. The paper then mainly focuses on spectrum sharing security and its related challenges. Since spectrum sharing is enabled through usage of the common control channel, more attention is paid to the security of the common control channel by looking into its security threats as well as protection and detection mechanisms. Finally, the pros and cons as well as the comparisons of different CR - specific security mechanisms are presented with some open research issues and challenges

Implementing opportunistic spectrum access in LTE-Advanced

Long term evolution advanced (LTE-A) has emerged as a promising mobile broadband access technology aiming to cope with the increasing traffic demand in wireless networks. However, the enhanced spectral efficiency offered by LTE-A may become futile without a better management of scarce and overcrowded electromagnetic spectrum. In this sense, cognitive radio (CR) has been proposed as a potential solution to the problem of spectrum scarcity. Among all the mechanisms provided by CR, opportunistic spectrum access (OSA) aims at a dynamic and seamless use of certain licensed bands provided the licensee is not harmfully affected. This operation requires spectral awareness in order to avoid interferences with licensed systems. In spite of implementing some spectrum sensing mechanisms, LTE-A technology lacks other tools that are needed in order to improve the knowledge of the radio environment. This work studies the adoption of a Geo-located data base (Geo-DB) that cooperatively retrieves and maintains information regarding the location of unutilized portions of spectrum potentially available for OSA. Moreover, the potential benefit of this LTE-compliant OSA solution is evaluated using a calibrated simulation tool, by which numerical results allow us to optimally configure the system and show that the proposed opportunistic system is able to significantly improve its performance.The authors would like to thank the funding received from the Ministerio de Ciencia e Innovacion within the Project number TEC2011-27723-C02-02 and from the Ministerio de Industria, Turismo y Comercio TSI-020100-2011-266 funds. This article had been written in the framework of the CELTIC project CP08-001 COMMUNE. Study by X. Gelabert is funded by the BP-DGR 2010 scholarship (ref. 00192). The authors would like to acknowledge the contributions of their colleagues.Osa Ginés, V.; Herranz Claveras, C.; Monserrat Del Río, JF.; Gelabert, X. (2012). Implementing opportunistic spectrum access in LTE-Advanced. EURASIP Journal on Wireless Communications and Networking. 2012(99):1-17. https://doi.org/10.1186/1687-1499-2012-99S117201299Martín-Sacristán D, Monserrat JF, Cabrejas-Peñuelas J, Calabuig D, Garrigas S, Cardona N: On the way towards fourth-generation mobile: 3GPP LTE and LTE-Advanced. EURASIP J Wirel Commun Netw 2009, 2009: 1-10.Ratasuk R, Tolli D, Ghosh A: Carrier aggregation in LTE-Advanced. In IEEE 71st Vehicular Technology Conference (VTC 2010-Spring). Taipei; 2010:1-5.Wang H, Rosa C, Pedersen K: Performance of uplink carrier aggregation in LTE-advanced systems. In IEEE 72nd Vehicular Technology Conference Fall (VTC 2010-Fall). Ottawa; 2010:1-5.Tandra R, Sahai A, Mishra S: What is a spectrum hole and what does it take to recognize one? 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Pacific Grove; 2004:772-776.Zeng Y, Liang YC, Hoang A, Peh E: Reliability of spectrum sensing under noise and interference uncertainty. In IEEE International Conference on Communications Workshops, 2009. ICC Workshops. Dresden; 2009:1-5.Bixio L, Ottonello M, Raffetto M, Regazzoni CS: Comparison among cognitive radio architectures for spectrum sensing. EURASIP J Wirel Commun Netw 2011, 2011: 1-18.Mustonen M, Matinmikko M, Mammela A: Cooperative spectrum sensing using quantized soft decision combining. In 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2009 (CROWNCOM'09). Hannover; 2009:1-5.Xiao L, Liu K, Ma L: A weighted cooperative spectrum sensing in cognitive radio networks. In International Conference on Information Networking and Automation (ICINA). Volume 2. Kunming; 2010:45-48.Pan Q, Chang Y, Zheng R, Zhang X, Wang Y, Yang D: Solution of information exchange for cooperative sensing in cognitive radios. 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Techniques for Efficient Spectrum Sensing in Heterogeneous Wireless Networks

Spectrum sensing is one of the most challenging and complex task in cognitive radio and it should be often performed by mobile devices with a limited battery life. So the development of efficient techniques for advanced spectrum sensing in heterogeneous, ad hoc environments, such as those in emergency situations, is of crucial importance. In this context spectrum sensing can be completed by the determination of the spatial coordinates of the devices in order to achieve the full potential of ad hoc networks management. In this work we present two techniques for improving the efficiency of mobile devices involved in spatial spectrum sensing: design of efficacious frequency synthesizers and hybrid localization for saving energy in the tracking process. Among the different frequency synthesis techniques, we focus on the phase-locked loop (PLL) approach and we consider the optimization of the loop filter for the PLL in the light of Wiener theory by taking into account the phase noise affecting the incoming carrier, the additive white Gaussian noise and the self-noise produced by the phase detector. Then we show an approach for improving the trade-off between energy consumption and performance in a localization tracking process, realized mixing active signal transmissions as well as passive signal reflections