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PHYSICS (582 journals)

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Journal Cover Physical Communication
  [SJR: 0.552]   [H-I: 19]   [1 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1874-4907
   Published by Elsevier Homepage  [3041 journals]
  • Effect of tunnel geometry and antenna parameters on through-the-air
           communication systems in underground mines: Survey and open research areas
           
    • Authors: Intikhab Hussain; Frederick Cawood; Rex van Olst
      Pages: 84 - 94
      Abstract: Publication date: Available online 10 March 2017
      Source:Physical Communication
      Author(s): Intikhab Hussain, Frederick Cawood, Rex van Olst
      In the mining industry, communication systems are important for ensuring personnel safety and optimizing the mining processes underground. The need for through-the-air (TTA) in the underground mining industry has been evolved from man-to-man, man-to-machine and machine-to-machine real-time voice, video and data transmission. Reliable communication has always been a challenge in the underground environment due to harsh and dynamic conditions. This article surveys the effect of tunnel geometry and antenna parameters on TTA communication system performance in underground mines. It provides a comprehensive review of measurement campaigns that have been published to date by systematic organization of literature. The open research areas for future investigation are also discussed. Finally, digital system ′ s findings in the University of Witwatersrand (WITS) mock-mine are presented.

      PubDate: 2017-03-13T02:56:33Z
      DOI: 10.1016/j.phycom.2017.03.002
      Issue No: Vol. 23 (2017)
       
  • Editorial for Physical Communication Journal 2016
    • Authors: Ian F. Akyildiz
      Abstract: Publication date: March 2017
      Source:Physical Communication, Volume 22
      Author(s): Ian F. Akyildiz


      PubDate: 2017-02-18T02:34:38Z
      DOI: 10.1016/s1874-4907(17)30037-x
      Issue No: Vol. 22 (2017)
       
  • Average symbol error rate and outage probability of DS-CDMA systems with
           AF relaying over asymmetric fading channels
    • Authors: Nuri Kapucu; Mehmet Bilim; Ibrahim Develi
      Abstract: Publication date: Available online 3 March 2017
      Source:Physical Communication
      Author(s): Nuri Kapucu, Mehmet Bilim, Ibrahim Develi
      In this paper, approximate outage probability (OP) and average symbol error rate (SER) of cooperative direct-sequence code-division multiple access (DS-CDMA) systems with amplify-and-forward (AF) relaying are evaluated over asymmetric fading channels. Practically, the channels between source ( S ) , relay ( R ) and destination ( D ) nodes in a DS-CDMA system can be subject to different fading due to the nature of wireless medium. Motivated by this reality, the S – D path is assumed to be Nakagami- m distributed which is a general fading model for different types of channel conditions while S – R and R – D paths are considered to experience Rician fading in order to include line of sight conditions. First, closed-form solutions are obtained for both the cumulative distribution function and the probability density function of S – R – D paths. Then, a closed-form total moment generating function (MGF) of the considered system is derived. The lower bound of the OP is calculated with the help of the inverse Laplace transform of the derived MGF expression while average SER is analyzed by evaluating the integral over the derived MGF. Finally, an asymptotic MGF expression is proposed for high signal-to-noise ratio (SNR) analysis of AF DS-CDMA systems. The simulation results are provided to verify the correctness of the analytical derivations. It is shown that the approximate OP and average SER results are in well agreement with the simulations and the asymptotic results are tight from medium to high SNR regime.

      PubDate: 2017-03-04T06:07:03Z
      DOI: 10.1016/j.phycom.2017.03.001
       
  • Distributed spatial modulation with dynamic frequency allocation
    • Authors: Kunal Sankhe; Sachin Chaudhari; Garimella Rama Murthy
      Abstract: Publication date: Available online 2 March 2017
      Source:Physical Communication
      Author(s): Kunal Sankhe, Sachin Chaudhari, Garimella Rama Murthy
      This paper proposes a distributed implementation of spatial modulation (SM) using cognitive radios. In distributed spatial modulation (DSM), multiple relays form a virtual antenna array and assist a source to transmit its information to a destination. The source broadcasts its signal, which is independently demodulated by all the relys. Each of the relays then divides the received data in two parts: the first part is used to decide which one of the relays will be active, and the other part decides what data it will transmit to the destination. An analytical expression for symbol error probability is derived for DSM in independent and identically distributed (i.i.d.) Rayleigh fading channels. The analytical results are later compared with Monte Carlo simulations. Further, an instantaneous symbol error rate (SER) based selection combining is proposed to incorporate the direct link between the source and destination with existing DSM. Next, DSM implementation is extended to a cognitive network scenario where the source, relays, and destination are all cognitive radios. A dynamic frequency allocation scheme is proposed to improve the performance of DSM in this scenario. The frequency allocation is modeled through a bipartite graph with end-to-end SER as a weight function. The optimal frequency allocation problem is formulated as minimum weight perfect matching problem and is solved using the Hungarian method. Finally, numerical results are provided to illustrate the efficacy of the proposed scheme.

      PubDate: 2017-03-04T06:07:03Z
      DOI: 10.1016/j.phycom.2017.02.005
       
  • Indoor cognitive radio operation within the broadcast TV protection
           contour
    • Authors: Meng-Jung Ho; Stevan M. Berber; Kevin W. Sowerby
      Abstract: Publication date: Available online 1 March 2017
      Source:Physical Communication
      Author(s): Meng-Jung Ho, Stevan M. Berber, Kevin W. Sowerby
      Although the broadcast television (TV) spectrum is currently open for unlicensed operation in the USA, a considerably large geographic area still remains excluded from the unlicensed operation due to potential interference to the licensed users. However, it might be possible to reuse primary spectrum within the protection contour if the frequency reuse occurs inside a building that shields radio signals and reduces interference to the primary system. Interference to outdoor licensed users from the indoor operations can be minimized if the unlicensed users adjust their transmit power according to their locations in the building. This paper presents an analysis and effectiveness evaluation of a novel cognitive radio (CR) system which enables CRs to access the licensed spectrum inside a building in the area within the protection contour. The system utilizes an indoor sensor network for (i) interference sensing, (ii) CR transmit power control, to limit the interference to the outdoor primary receiving antennas. Power control model of the indoor system has been developed to estimate safe transmit power for the indoor users. Two cases have been considered; single-user single-sensor (single indoor user and single sensor), and multi-user multi-sensor. Based on the power control model, a power control algorithm has been developed and its effectiveness is assessed through simulations. The algorithm is effective in realistic propagation scenarios, e.g. when internal partition walls and multipath fading are present. The outage probabilities in these propagation scenarios are found and the procedure of determining the transmit powers for CRs is presented.

      PubDate: 2017-03-04T06:07:03Z
      DOI: 10.1016/j.phycom.2017.02.006
       
  • Gerchberg–Saxton algorithm based phase correction in optical
           wireless communication
    • Authors: Ming Li; Yupeng Li; Jiawei Han
      Abstract: Publication date: Available online 1 March 2017
      Source:Physical Communication
      Author(s): Ming Li, Yupeng Li, Jiawei Han
      Optical wireless communication (OWC) enables to establish the backhaul in the fifth generation (5G) wireless communication networks. The air turbulence, however, could distort the phases of optical signals, thus limit transmission capacity. In this paper, we study the correction of phase distortions by using the Gerchberg–Saxton (GS) algorithm. The air turbulence-induced phase is generated by the Monte-Carlo phase screen method, which characterizes the realistic air turbulence effect on the optical signals. The numerical results reveal that the GS algorithm is able to retrieve the phase information with fast convergence by adopting a proper initial condition. Also, the GS algorithm based phase correction in OWC is confirmed.

      PubDate: 2017-03-04T06:07:03Z
      DOI: 10.1016/j.phycom.2017.02.008
       
  • MIMO-OFDM underwater acoustic communication systems–A review
    • Authors: Gang Qiao; Zeeshan Babar; Lu Ma; Songzuo Liu; Jinqiu Wu
      Abstract: Publication date: Available online 1 March 2017
      Source:Physical Communication
      Author(s): Gang Qiao, Zeeshan Babar, Lu Ma, Songzuo Liu, Jinqiu Wu
      The ever increasing demand for bandwidth, efficiency, spatial diversity and performance of underwater acoustic (UWA) communication has opened doors for the use of Multi-Input Multi-Output (MIMO). A combination of MIMO and Orthogonal Frequency Division Multiplexing (OFDM) has proved to be a promising solution for many scenarios in UWA communication; on the contrary, it also amplifies the design challenges for implementing such schemes to acquire the required bandwidth efficiency. The goal of this study is to provide a comprehensive survey of the latest researches in the field of UWA MIMO-OFDM communication. The previous works are summarized, reviewed and compared according to their years of publication while problems faced by UWA MIMO-OFDM communication are highlighted. The articles are classified according to the focused techniques like channel estimation, equalization, coding and detection. Furthermore the works are compared based on the complexity and performance of the algorithms while some future research issues are identified.

      PubDate: 2017-03-04T06:07:03Z
      DOI: 10.1016/j.phycom.2017.02.007
       
  • Investigation of quadrature imbalance compensation algorithm for coherent
           6PolSK-QPSK
    • Authors: Yupeng Li; Ming Li; Jiawei Han; Tingting Han
      Abstract: Publication date: Available online 16 February 2017
      Source:Physical Communication
      Author(s): Yupeng Li, Ming Li, Jiawei Han, Tingting Han
      6PolSK-QPSK is a promising modulation format in optical fiber communication. Because of the damage suffered during the transmission and reception, a series of algorithms are needed to be adopted to recover the original data. We proposed a novel quadrature imbalance compensation algorithm based on the data statistical properties. Simulation results show that the quadrature imbalance can be well compensated with the proposed algorithm.

      PubDate: 2017-02-18T02:34:38Z
      DOI: 10.1016/j.phycom.2017.02.004
       
  • Performance analysis of relay-assisted uplink massive MIMO systems with
           zero-forcing receiver
    • Authors: Liang Han; Weixia Zou
      Abstract: Publication date: Available online 16 February 2017
      Source:Physical Communication
      Author(s): Liang Han, Weixia Zou
      As one of the most promising candidate technique for the fifth generation (5G) wireless network, massive multiple-input multiple-output (MIMO) has attracted much research interests. However, due to the high path loss and severe shadowing, the cell-edge users may have very poor performance in uplink massive MIMO systems. To overcome this problem, we investigate relay-assisted uplink massive MIMO systems, where K single-antenna users communicate with an N -antenna base station (BS) through an M -antenna relay and N is very large. We use amplify-and-forward (AF) relaying schemes which simply forward scaled versions of its received signals. Assuming the BS can obtain perfect channel state information (CSI) of all the user-relay links and relay-BS links, zero-forcing (ZF) receiver is adopted at the BS. Based on these assumptions, we derive the closed-form expressions for the ergodic achievable rate and outage probability. Numerical and simulation results validate our analysis and show that the relay-assisted massive MIMO systems achieve better performance than direct transmission massive MIMO systems when the links from the users to the BS are weak.

      PubDate: 2017-02-18T02:34:38Z
      DOI: 10.1016/j.phycom.2017.02.001
       
  • Investigation of 64-QAM optical modulator with paralleled dual-drive MZMs
           driven by binary signals
    • Authors: Yupeng
      Abstract: Publication date: Available online 16 February 2017
      Source:Physical Communication
      Author(s): Yupeng Li
      High-order Quadrature amplitude modulation (QAM) is a promising approach to increase the spectral efficiency of wavelength-division-multiplexing (WDM) transmission. However, the optical implementation is still challenging. A customized modulator is proposed for 64-QAM signal generation, and its performance is investigated in detail.

      PubDate: 2017-02-18T02:34:38Z
       
  • Characterization of distributed mode crosstalk in few-mode fiber links
           with low MIMO complexity
    • Authors: Jiawei Han; Caifeng Qu
      Abstract: Publication date: Available online 16 February 2017
      Source:Physical Communication
      Author(s): Jiawei Han, Caifeng Qu
      We theoretically model and numerically analyze the linear behavior of distributed mode crosstalk in a step-index weakly-coupled 7-mode fiber. This fiber is assumed to be used for one-polarization uncoupled mode-division multiplexing (MDM) systems with: (1) sparse MIMO equalizers which are performed over only degenerate LP modes, or (2) one single differential mode delay-independent MIMO equalizer which is performed over all non-degenerate LP modes. For the above two low-complexity MIMO configuration schemes, the impacts of distributed mode coupling on the multi-path interference-dependent achievable distance and system quality are empirically evaluated, through the numerical simulations for uncoupled MDM transmissions of a single-channel 28 GBaud QPSK signal over the fiber.

      PubDate: 2017-02-18T02:34:38Z
      DOI: 10.1016/j.phycom.2017.02.002
       
  • Traffic-aware green cognitive radio
    • Authors: Washim Uddin Mondal; Sudipta Biswas; Goutam Das; Priyadip Ray
      Abstract: Publication date: Available online 27 January 2017
      Source:Physical Communication
      Author(s): Washim Uddin Mondal, Sudipta Biswas, Goutam Das, Priyadip Ray
      Cognitive Radio Network (CRN) has emerged as an effective solution to the spectrum under-utilization problem, by providing secondary users (SUs) an opportunistic access to the unoccupied frequency bands of primary users (PUs). Most of the current research on CRN are based on the assumption that the SU always has a large amount of data to transmit. This leads to the objective of SU throughput maximization with a constraint on the allowable interference to the PU. However, in many of the practical scenarios, the data arrival process of the SU closely follows an ON–OFF traffic model, and thus the usual throughput optimization framework may no longer be suitable. In this paper, we propose an intelligent data scheduling strategy which minimizes the average transmission power of the SU while maintaining the transmission delay to be sufficiently small. The data scheduling problem has been formulated as a finite horizon Markov Decision Process (MDP) with an appropriate cost function. Dynamic programming approach has been adopted to arrive at an optimal solution. Our findings show that the average transmitted power for our proposed approach can be as small as 36.5% of the power required for usual throughput maximization technique with insignificant increase in average delay.

      PubDate: 2017-01-28T19:33:32Z
      DOI: 10.1016/j.phycom.2017.01.002
       
  • Multiuser detection for the uplink of clustered 5G systems with universal
           frequency reuse
    • Authors: F. Casal Ribeiro; R. Dinis; F. Cercas; A. Silva
      Abstract: Publication date: Available online 24 January 2017
      Source:Physical Communication
      Author(s): F. Casal Ribeiro, R. Dinis, F. Cercas, A. Silva
      With 5G (Fifth generation) cellular communications, systems have to be able to cope with a massive increase of mobile devices and services and simultaneously improve the system’s spectral efficiency, as well as dealing with high interference levels. Base Station (BS) cooperation architectures jointly with block transmission techniques, such as OFDM (Orthogonal Frequency Division Multiplexing) for the downlink and SC-FDE (Single-Carrier with Frequency-Domain Equalization) for the uplink, are proven to be suitable for broadband wireless transmission systems. In BS cooperation systems MTs (Mobile Terminals) in adjacent cells share the same physical channel allowing the reducing of the frequency reuse and improving the spectral efficiency of cellular systems. In this paper we present a set of multiuser detection techniques for the uplink transmission in clustered architectures based on the C-RAN (Centralized-Radio Access Network) concept. We consider BS cooperation systems employing a universal frequency reuse approach. Our performance results demonstrate that by employing clustered techniques for the detection procedure it is possible to reduce substantially the signal processing complexity and the side information that must be transmitted by the backhaul structure.

      PubDate: 2017-01-28T19:33:32Z
      DOI: 10.1016/j.phycom.2017.01.006
       
  • Power control based on the Stackelberg game in two-tier femtocell networks
    • Authors: Zhixin Liu; Shiyi Li; Lili Hao; Hongjiu Yang; Xinping Guan; Xinbin Li
      Abstract: Publication date: Available online 21 January 2017
      Source:Physical Communication
      Author(s): Zhixin Liu, Shiyi Li, Lili Hao, Hongjiu Yang, Xinping Guan, Xinbin Li
      In this paper, the resource allocation strategy is investigated for a spectrum sharing two-tier femtocell networks, in which a central macrocell is underlaid with distributed femtocells. The spectral radius is introduced to address the conditions that any feasible set of users’ signal-to-interference-plus-noise ratio requirements should satisfy in femtocell networks. To develop power allocation scheme with the derived conditions, a Stackelberg game is formulated, which aims at the utility maximization both of the macrocell user and femtocell users. The distributed power control algorithm is given to reduce the cross-tier interference between the macrocell and femtocell with same channel. At last, admission control algorithm is proposed, aiming to exploit the network resource effectively. Numerical results show that the proposed resource allocation schemes are effective in reducing power consumption and more suitable in the densely deployed scenario of the femtocell networks. Meanwhile, it also presents that the distributed power allocation scheme combined with admission control can protect the performance of all active femtocell users in a robust manner.

      PubDate: 2017-01-22T16:39:22Z
      DOI: 10.1016/j.phycom.2017.01.005
       
  • Computation of information rates by means of discrete states density
           recursion
    • Authors: L. Reggiani; L. Dossi
      Abstract: Publication date: Available online 20 January 2017
      Source:Physical Communication
      Author(s): L. Reggiani, L. Dossi
      Starting from the existing works on the computation of information rates of channels with memory, we present a modification of these methods that can be used for continuous-state space models. The principle used for developing this alternative method is based on the partitioning of the continuous-state space into sub-sets, each one representing a state of a trellis, and the association between the states and the probability density functions built and updated on such sub-sets. The paper discusses the cases in which the method provides a computational advantage and it presents numerical results regarding the relevant example of the Wiener phase noise model.

      PubDate: 2017-01-22T16:39:22Z
      DOI: 10.1016/j.phycom.2017.01.004
       
  • Multi-channel sensing and resource allocation in energy constrained
           cognitive radio networks
    • Authors: Kedar Kulkarni; Adrish Banerjee
      Abstract: Publication date: Available online 20 January 2017
      Source:Physical Communication
      Author(s): Kedar Kulkarni, Adrish Banerjee
      We consider a cognitive radio network in a multi-channel licensed environment. Secondary user transmits in a channel if the channel is sensed to be vacant. This results in a tradeoff between sensing time and transmission time. When secondary users are energy constrained, energy available for transmission is less if more energy is used in sensing. This gives rise to an energy tradeoff. For multiple primary channels, secondary users must decide appropriate sensing time and transmission power in each channel to maximize average aggregate-bit throughput in each frame duration while ensuring quality-of-service of primary users. Considering time and energy as limited resources, we formulate this problem as a resource allocation problem. Initially a single secondary user scenario is considered and solution is obtained using decomposition and alternating optimization techniques. Later we extend the analysis for the case of multiple secondary users. Simulation results are presented to study effect of channel occupancy, fading and energy availability on performance of proposed method.

      PubDate: 2017-01-22T16:39:22Z
      DOI: 10.1016/j.phycom.2017.01.003
       
  • Transport capacity of cooperative cognitive radio ad hoc networks
    • Authors: Jing Gao; Yinghui Zhang; Yang Liu
      Abstract: Publication date: Available online 18 January 2017
      Source:Physical Communication
      Author(s): Jing Gao, Yinghui Zhang, Yang Liu
      It is more challenging for improving the traditional performance metrics for the 5-th generation network (5G) because of more congestible frequency spectrum. How to improve the network capacity without using more spectrum has become one of important studies in 5G. In this paper, the transport capacity of cooperative cognitive radio ad hoc networks is studied. In order to characterize the transport capacity, a half-slotted ALOHA multiple access protocol is introduced. In each slot, secondary users are divided into cooperative secondary users and ordinary users dependent on the positional relationship between them and primary transmitters. Primary transmitters send their packets in the first half slot while keep silence in the second half slot. Ordinary secondary users send their packets at a probability p in the whole slot. Cooperative secondary users receive the packets from their corresponding primary transmitters in the first half slot and forward them to the primary receivers in the second half slot. The closed-form expressions of the bounds of primary transport capacity and mean secondary transport capacity are derived based on the protocol. Furtherly, the optimal problem of the performance is analyzed about two important parameters: primary and secondary coverage radius. Theoretical results show that an optimal primary coverage radius could be found to maximize the transport capacity of primary network. While the transport capacity of secondary network increases with the increasing secondary coverage radius. The analysis reveals that the transport capacity could be improved by secondary cooperation because of higher successful transmission probability.

      PubDate: 2017-01-22T16:39:22Z
      DOI: 10.1016/j.phycom.2017.01.001
       
  • On the design of a multi-carrier correlation delay-shift keying system
    • Authors: Nguyen Xuan Quyen
      Abstract: Publication date: Available online 15 January 2017
      Source:Physical Communication
      Author(s): Nguyen Xuan Quyen
      This paper presents the design of a multi-carrier correlation delay-shift keying (MC-CDSK) system for the operation in wireless environments. In the proposed system, the sum of a chaotic sequence and it delayed version is considered to be a reference sequence and transmitted through a predefined subcarrier. The input data is divided into multiple pairs of bit sub-sequences, where the first and second ones of each pair are spread in the frequency domain by directly multiplying with the chaotic sequence and the delayed version, respectively. The sum of two resulting signals for each pair is then transmitted on a corresponding subcarrier. In the receiving side, the reference sequence retrieved from the predefined subcarrier and the signal retrieved from each of the remaining subcarriers are correlated with the delayed version of the other ones to recover the corresponding bit sub-sequence pair. The recovered pairs are combined to an output data. Schemes for the transmitter and receiver are designed and their operation over a multipath Rayleigh fading channel is described. The system performance is evaluated via theoretical analysis and then verified by numerical simulation. Our findings show that MC-CDSK system can improve communication features, i.e., bit error rate (BER) performance, energy and spectrum efficiency compared to those of the conventional CDSK.

      PubDate: 2017-01-15T14:25:05Z
      DOI: 10.1016/j.phycom.2016.12.004
       
  • Finite-SNR outage analysis for MIMO channels with imperfect channel state
           information
    • Authors: Nandita Lavanis; Devendra Jalihal; Arun Pachai Kannu; Srikrishna Bhashyam
      Abstract: Publication date: Available online 10 January 2017
      Source:Physical Communication
      Author(s): Nandita Lavanis, Devendra Jalihal, Arun Pachai Kannu, Srikrishna Bhashyam
      In this paper, a point-to-point multiple-input multiple-output (MIMO) channel with imperfect channel state information (CSI) at the receiver and no CSI at the transmitter is considered. Using Monte Carlo simulations, we compute the optimum number of active antennas required at the transmitter ( t opt ) to minimize the outage probability. We show that, apart from the number of transmit antennas, t opt depends on the signal to noise ratio (SNR), multiplexing gain, coherence time, and the number of receive antennas. Our results give insights on the behavior of t opt with respect to these parameters. Specifically, we show that as the multiplexing gain increases, the value of t opt increases from one, and as the multiplexing gain reaches its maxima, the value of t opt equals the minimum of the number of transmit and receive antennas. The intermediate behavior of t opt with respect to multiplexing gain depends on the MIMO channel configuration. t opt for the MIMO channel with perfect CSI at the receiver follows a similar pattern as that with imperfect CSIR. For a multiple-input single-output (MISO) channel with imperfect CSIR, we obtain a tight upper bound on the outage probability. Using this analytical upper bound, we can calculate t opt for any fixed channel configuration. For a MISO channel with imperfect CSIR and fixed SNR, t opt reduces as multiplexing gain increases; however, for fixed multiplexing gain and fixed SNR, t opt monotonically increases with increase in coherence time of the channel.

      PubDate: 2017-01-15T14:25:05Z
      DOI: 10.1016/j.phycom.2016.12.005
       
  • Distributed power allocation for spectrum sharing in mutually interfering
           wireless systems
    • Authors: Saygın Bakşi; Dimitrie C. Popescu
      Abstract: Publication date: Available online 5 January 2017
      Source:Physical Communication
      Author(s): Saygın Bakşi, Dimitrie C. Popescu
      Allocation of transmit power is critical for spectrum sharing and coexistence of mutually interfering wireless systems. In this paper we present a novel approach for allocation of transmit power, which is based on a non-greedy procedure that aims at maximizing transmission rate while also controlling interference levels. The proposed approach is fully distributed and requires no central control or coordination. Numerical results obtained from simulations are presented to illustrate the performance of the proposed approach in both sparse and dense environments. In sparse wireless environments, where there are fewer mutually interfering wireless links than available frequency bands, the proposed approach yields power allocations which outperform those obtained by applying alternative power allocation strategies, while in dense environments, where there are more interfering links than available frequency bands, the proposed approach yields power allocations with performance similar to those of existing power strategies. Thus, the distributed power allocation procedure based on the proposed approach is a drop-in replacement algorithm that yields better system throughput than existing algorithms for spectrum sharing.

      PubDate: 2017-01-07T12:21:07Z
      DOI: 10.1016/j.phycom.2016.12.003
       
  • A fractional path-loss compensation based power control technique for
           interference mitigation in LTE-A femtocell networks
    • Authors: Sawsan Ali Saad; Mahamod Ismail; Rosdiadee Nordin; Afaz Uddin Ahmed
      Pages: 1 - 9
      Abstract: Publication date: Available online 15 March 2016
      Source:Physical Communication
      Author(s): Sawsan Ali Saad, Mahamod Ismail, Rosdiadee Nordin, Afaz Uddin Ahmed
      Introduction of Femtocells in heterogeneous network enhances the capacity, indoor coverage of the existing macrocell based network. It also allows high-speed data services for the multi-media application and software. However, in dense co-channel deployment scenarios femtocells cause severe interference to the neighbouring cells users. In this paper, a downlink-power-control scheme is presented for femtocell with no overhead signalling exchange with the macrocell. The femtocell adjusts the transmit power subject to home user equipment (HUE) measurements. The minimum level of transmit power is determined by the target Signal to Interference and Noise Ratio (SINR) of femtocell user that is set according to the required Quality of Service (QoS) of the femtocell users. The system level simulations confirm that, the proposed scheme reduces the outage probability of the nearby macrocell user equipment (MUE) up to 16.7% compared to fixed power setting, while maintaining the spectral efficiency of femtocell users. Furthermore, the transmit power can be reduced by 52.6% which leads to power effective solution of the interference scenario.

      PubDate: 2016-03-18T13:41:49Z
      DOI: 10.1016/j.phycom.2016.02.003
      Issue No: Vol. 21 (2016)
       
  • Automatic modulation classification based on high order cumulants and
           hierarchical polynomial classifiers
    • Authors: Ameen Abdelmutalab; Khaled Assaleh; Mohamed El-Tarhuni
      Pages: 10 - 18
      Abstract: Publication date: December 2016
      Source:Physical Communication, Volume 21
      Author(s): Ameen Abdelmutalab, Khaled Assaleh, Mohamed El-Tarhuni
      In this paper, a Hierarchical Polynomial (HP) classifier is proposed to automatically classify M-PSK and M-QAM signals in Additive White Gaussian Noise (AWGN) and slow flat fading environments. The system uses higher order cumulants (HOCs) of the received signal to distinguish between the different modulation types. The proposed system divides the overall modulation classification problem into several hierarchical binary sub-classifications. In each binary sub-classification, the HOCs are expanded into a higher dimensional space in which the two classes are linearly separable. It is shown that there is a significant improvement when using the proposed Hierarchical polynomial structure compared to the conventional polynomial classifier. Moreover, simulation results are shown for different block lengths (number of received symbols) and at different SNR values. The proposed system showed an overall improvement in the probability of correct classification that reaches 100% using only 512 received symbols at 20 dB compared to 98% and 98.33% when using more complicated systems like Genetic Programming with KNN classifier (GP-KNN) and Support Vector Machines (SVM) classifiers, respectively.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.08.001
      Issue No: Vol. 21 (2016)
       
  • Power allocation in multi-hop OFDM transmission systems with
           amplify-and-forward relaying: A unified approach
    • Authors: Amin Azari; Jalil S. Harsini; Farshad Lahouti
      Pages: 19 - 29
      Abstract: Publication date: December 2016
      Source:Physical Communication, Volume 21
      Author(s): Amin Azari, Jalil S. Harsini, Farshad Lahouti
      In this paper, a unified approach for power allocation (PA) in multi-hop orthogonal frequency division multiplexing (OFDM) amplify-and-forward (AF) relaying systems is presented. In the proposed approach, we consider short and long term individual and total power constraints at the source and relays, and devise low complexity PA algorithms when wireless links are subject to channel path-loss and small-scale Rayleigh fading. To manage the complexity, in the proposed formulations, we adopt a two-stage iterative approach consisting of a power distribution phase among distinct subcarriers, and a power allocation phase among different relays. In particular, aiming at improving the instantaneous rate of multi-hop transmission systems with AF relaying, we develop (i) a near-optimal iterative PA algorithm based on the exact analysis of the received SNR at the destination; (ii) a low complexity suboptimal iterative PA algorithm based on an approximate expression of the received SNR at high-SNR regime; and (iii) a low complexity non-iterative PA scheme with limited performance loss. Simulation results show the superior performance of the proposed power allocation algorithms.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.07.002
      Issue No: Vol. 21 (2016)
       
  • A very tight approximate results of MRC receivers over independent Weibull
           fading channels
    • Authors: Abdelmajid Bessate; Faissal El Bouanani
      Pages: 30 - 40
      Abstract: Publication date: December 2016
      Source:Physical Communication, Volume 21
      Author(s): Abdelmajid Bessate, Faissal El Bouanani
      In this paper, we study the performance of L -branch maximal-ratio combining (MRC) receivers operating over independent Weibull-fading channels. Our main result is a very tight approximation of the probability density function (PDF) of the signal-to-noise ratio (SNR) at the output of the combiner. Based on this result, accurate approximation of significant performance criteria, such as outage probability and average symbol error rate (ASER) are derived. We also evaluate the average bit error rate (ABER) for several coherent and non-coherent modulation schemes, using a closed-form expression for the moment-generating function (MGF) of the output SNR for MRC receivers. In addition, we derive some analytical expressions for channel capacity under various adaptation policies such as optimal rate adaptation (ORA), Optimal simultaneous power and rate adaptation (OPRA), Channel inversion with fixed rate (CIFR), and Truncated channel inversion with fixed rate (TCIFR). The proposed mathematical analysis is complemented by numerous numerical results, which point out the effects of fading severity on the overall system performance. Computer simulations are also performed to verify the validity and the accuracy of the proposed theoretical approach.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.09.001
      Issue No: Vol. 21 (2016)
       
  • Editorial: Passing the baton
    • Authors: Ian F. Akyildiz
      Abstract: Publication date: September 2016
      Source:Physical Communication, Volume 20
      Author(s): Ian F. Akyildiz


      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/s1874-4907(16)30079-9
      Issue No: Vol. 20 (2016)
       
  • Editorial: Receiving the baton
    • Authors: Tolga M. Duman
      Abstract: Publication date: September 2016
      Source:Physical Communication, Volume 20
      Author(s): Tolga M. Duman


      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/s1874-4907(16)30080-5
      Issue No: Vol. 20 (2016)
       
  • On-demand multimedia data broadcast in MIMO wireless networks
    • Authors: Ping He; Hong Shen
      Pages: 1 - 16
      Abstract: Publication date: Available online 2 May 2016
      Source:Physical Communication
      Author(s): Ping He, Hong Shen
      Given a set of multiple requests from clients equipped with M antennae and a wireless network of m channels, on-demand data broadcast requires to find an optimal schedule of broadcasting (placing) all requested data items of R on a set of channels C as evenly as possible under the constraint that each client may use at most M channels. Such a schedule is important for overcoming the shortcomings of wireless networks such as asymmetric bandwidth between uplink and downlink, and limited battery life of mobile devices. Existing schemes for data broadcast assume single-antenna clients and will result in significant bandwidth wastage and client’s data download time increase. To overcome these problems, we propose a novel approach for disseminating multimedia data in an MIMO wireless network by converting it to the multiprocessor scheduling problem where requests and antennae are regarded as tasks and processors respectively. We present three schemes (LFOS, BFOS and BBOS) under this approach: LFOS scheduling data items of largest sizes, BFOS adopting the best matching between data items and channels, and BBOS partitioning data items properly to balance the broadcast cycles of all channels. In comparison with the existing schemes based on single-antenna broadcast, our schemes improve access latency and channel bandwidth usage significantly. This has been verified through extensive experimental results.

      PubDate: 2016-05-03T02:43:56Z
      DOI: 10.1016/j.phycom.2016.04.003
      Issue No: Vol. 20 (2016)
       
  • Performance evaluation of FRESH filter based spectrum sensing for
           cyclostationary signals
    • Authors: Ribhu Chopra; Debashis Ghosh; D.K. Mehra
      Pages: 17 - 32
      Abstract: Publication date: Available online 9 May 2016
      Source:Physical Communication
      Author(s): Ribhu Chopra, Debashis Ghosh, D.K. Mehra
      This paper considers the problem of spectrum sensing of cyclostationary signals for cognitive radios. It has been reported earlier using simulation results that FRESH filtering a signal, prior to spectrum sensing, may result in gains of more than 5 dB over the standard energy and cyclostationary detectors. This paper develops a quasi-analytical theory of spectrum sensing based on FRESH filtering. It is shown that significant performance gains are achievable in both energy detection and cyclostationarity detection via FRESH filtering of the received signal prior to the detection step. The aforementioned approach may be shown to reduce the number of samples required to achieve a given detection performance by more than 90% in practice, thereby reducing the sensing time in a cognitive radio system. It is also shown that the FRESH filtering before energy detection may reduce the effects of SNR walls caused due to noise uncertainty. The validity of all the derived observations is verified via simulations.

      PubDate: 2016-05-14T08:11:11Z
      DOI: 10.1016/j.phycom.2016.04.004
      Issue No: Vol. 20 (2016)
       
  • Radar interference into LTE base stations in the 3.5 GHz band
    • Authors: Mo Ghorbanzadeh; Eugene Visotsky; Prakash Moorut; Charles Clancy
      Pages: 33 - 47
      Abstract: Publication date: Available online 11 May 2016
      Source:Physical Communication
      Author(s): Mo Ghorbanzadeh, Eugene Visotsky, Prakash Moorut, Charles Clancy
      We study the interference from a rotating shipborne radar system that spectrally and spatially coexists with a Long Term Evolution (LTE) cellular communications network in the 3.5 GHz band to investigate the feasibility of LTE deployment in the United States coastal metropolitan cities in that band. First, we simulate the radar systems with realistic operational parameters. Furthermore, we leverage a detailed 3GPP-compliant LTE simulation with a sophisticated air interface modeling and investigate sensitivity of LTE to radar interference in macro cell, outdoor small cell, and indoor small cell scenarios. We simulate the propagation conditions between the radar and LTE system by adopting the Free Space Path Loss and Irregular Terrain Model commonly leveraged by National Telecommunications and Information Administration (NTIA), to account for propagation, diffraction, and troposcatter losses that the radar pulses undergo before they reach the LTE system. As a performance metric, we evaluate the throughput of the LTE system in the uplink direction for various distances between the radar and the cellular system. Our simulation results indicate an LTE link will remain operational even in severe interference conditions. In fact, the LTE system as close as 100 km away from the radar undergoes less than 10 % throughput loss from the LTE total throughput, and the throughput loss is less than 30 % when the radar is only 50 km away from the LTE.

      PubDate: 2016-05-14T08:11:11Z
      DOI: 10.1016/j.phycom.2016.04.005
      Issue No: Vol. 20 (2016)
       
  • A survey on compressive sensing techniques for cognitive radio networks
    • Authors: Fatima Salahdine; Naima Kaabouch; Hassan El Ghazi
      Pages: 61 - 73
      Abstract: Publication date: Available online 31 May 2016
      Source:Physical Communication
      Author(s): Fatima Salahdine, Naima Kaabouch, Hassan El Ghazi
      In cognitive radio, one of the main challenges is wideband spectrum sensing. Existing spectrum sensing techniques are based on a set of observations sampled by an analog/digital converter (ADC) at the Nyquist rate. However, those techniques can sense only one band at a time because of the hardware limitations on sampling rate. In addition, in order to sense a wideband spectrum, the band is divided into narrow bands or multiple frequency bands. Secondary users (SU) have to sense each band using multiple RF frontends simultaneously, which results in a very high processing time, hardware cost, and computational complexity. In order to overcome this problem, the signal sampling should be as fast as possible, even with high dimensional signals. Compressive sensing has been proposed as one of the solutions to reduce the processing time and accelerate the scanning process. It allows reducing the number of samples required for high dimensional signal acquisition while keeping the important information. Over the last decade, a number of papers related to compressive sensing techniques have been published. However, most of these papers describe techniques corresponding to one process either sparse representation, sensing matrix, or recovery. This paper provides an in depth survey on compressive sensing techniques and classifies these techniques according to which process they target, namely, sparse representation, sensing matrix, or recovery algorithms. It also discusses examples of potential applications of these techniques including in spectrum sensing, channel estimation, and multiple-input multiple-output (MIMO) based cognitive radio. Metrics to evaluate the efficiencies of existing compressive sensing techniques are provided as well as the benefits and challenges in the context of cognitive radio networks.

      PubDate: 2016-06-16T18:20:32Z
      DOI: 10.1016/j.phycom.2016.05.002
      Issue No: Vol. 20 (2016)
       
  • Utility-based resource allocation for interference limited OFDMA
           cooperative relay networks
    • Authors: Nidhal Odeh; Mehran Abolhasan; Farzad Safaei; Daniel R. Franklin; Guoqiang Mao
      Pages: 74 - 84
      Abstract: Publication date: Available online 25 May 2016
      Source:Physical Communication
      Author(s): Nidhal Odeh, Mehran Abolhasan, Farzad Safaei, Daniel R. Franklin, Guoqiang Mao
      This paper proposes a utility-based resource allocation algorithm for the uplink OFDMA Inter-cell Interference (ICI) limited cooperative relay network. Full channel state information (CSI) is assumed to be available at the resource controller at initial stage, then the work is extended to consider more realistic assumption, i.e., only partial channel state information (PCSI) is available. The proposed algorithm aims to maximize the total system utility while simultaneously satisfying the individual user’s minimum data rate requirements. In the proposed algorithm, relay selection is initially performed based on the consideration of ICI. Then, subcarrier allocation is performed to achieve maximum utility assuming equal power allocation. Finally, based on the amount of ICI, a modified water-filling power distribution algorithm is proposed and used to optimize the per-carrier power allocation across the allocated set of subcarriers. The results show that, compared to conventional algorithms, the proposed algorithm significantly improves system performance in terms of total sum data rate, outage probability and fairness.

      PubDate: 2016-06-16T18:20:32Z
      DOI: 10.1016/j.phycom.2016.05.001
      Issue No: Vol. 20 (2016)
       
  • Error rate analysis of AF-relay wireless networks under different SNR
           levels
    • Authors: Muhammad I. Khalil; Stevan M. Berber; Kevin W. Sowerby
      Pages: 85 - 92
      Abstract: Publication date: September 2016
      Source:Physical Communication, Volume 20
      Author(s): Muhammad I. Khalil, Stevan M. Berber, Kevin W. Sowerby
      This paper presents a new method for analyzing the Bit Error Rate (BER) performance of two-hop Amplify-and-Forward Multiple Relay (AF-MR) networks. This paper considers, a flat-fading channel and a relay selection scheme to select a relay with the highest Signal-to-Noise Ratio (SNR). The method aims to unify the BER calculation under low, high and optimal SNR levels. Asymptotic BER (ABER) performance at high SNR value is calculated first, and standard expressions for exact BER (EBER) performance at low and optimal SNRs are then derived. The analytic method depends on the conventional BER (CBER) approach of one-hop communication systems. The optimal SNR is obtained by balancing energy efficiency and spectral efficiency. The proposed method is found to be effective for calculating the BER of AF-MR network performance under any SNR conditions. Moreover, it improves the accuracy of ABER performance by reducing disparity computation errors between ABER and EBER performances and this allows the BER of AF-MR networks to be accurately calculated using either ABER or EBER. The outcome expressions for the method are validated by simulation results.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.06.002
      Issue No: Vol. 20 (2016)
       
  • Recent trends in multiuser detection techniques for SDMA–OFDM
           communication system
    • Authors: Kala Praveen Bagadi; Visalakshi Annepu; Susmita Das
      Pages: 93 - 108
      Abstract: Publication date: September 2016
      Source:Physical Communication, Volume 20
      Author(s): Kala Praveen Bagadi, Visalakshi Annepu, Susmita Das
      The space division multiple access–orthogonal frequency division multiplexing (SDMA–OFDM) technique is emerged as a most competitive technology for future wireless communication system as it can provide high spectral efficiency and resistance from inter symbol interference (ISI). The SDMA like multiple access techniques are prone to multiple access interference (MAI) because multiple users transmit their data simultaneously. Such a receiver requires appropriate multiuser detection (MUD) scheme to detect individual user’s signals correctly by mitigating MAI. Further, due to non-linear behaviour of wireless channel, the signals at SDMA receiver often become linearly non-separable. As a result, MUD becomes a challenging multidimensional optimization problem. Considering these challenges, this paper reviews various MUD techniques for SDMA–OFDM system.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.07.001
      Issue No: Vol. 20 (2016)
       
  • Cooperative spectrum sharing MIMO systems with successive decoding
    • Authors: Nikolaos I. Miridakis; Dimitrios D. Vergados; Angelos Michalas
      Pages: 109 - 122
      Abstract: Publication date: Available online 14 January 2016
      Source:Physical Communication
      Author(s): Nikolaos I. Miridakis, Dimitrios D. Vergados, Angelos Michalas
      A spectrum sharing system with primary and secondary nodes, each equipped with an arbitrary number of antennas, is investigated. Particularly, the outage performance of an underlay cognitive system is analytically studied, in the case when the end-to-end ( e 2 e ) communication is established via an intermediate relay node. To better enhance the e 2 e communication, successive interference cancellation (SIC) is adopted, which compensates for both the transmission power constraint and the presence of interference from primary nodes. Both the relay and secondary receiver perform unordered SIC to successively decode the multiple streams, whereas the decode-and-forward relaying protocol is used for the e 2 e communication. New closed-form expressions for the e 2 e outage performance of each transmitted stream are derived in terms of finite sum series of the Tricomi confluent hypergeometric function. In addition, simplified yet tight approximations for the asymptotic outage performance are obtained. Useful engineering insights are manifested, such as the diversity order of the considered system and the impact of interference from the primary nodes in conjunction with the constrained transmission power of the secondary nodes.

      PubDate: 2016-01-15T11:19:49Z
      DOI: 10.1016/j.phycom.2016.01.002
      Issue No: Vol. 20 (2016)
       
  • Joint optimization of component carrier selection and resource allocation
           in 5G carrier aggregation system
    • Authors: Weidong Gao; Lin Ma; Gang Chuai
      Abstract: Publication date: Available online 24 December 2016
      Source:Physical Communication
      Author(s): Weidong Gao, Lin Ma, Gang Chuai
      In this paper, we consider joint optimization of Component Carrier (CC) selection and resource allocation in 5G Carrier Aggregation (CA) system. Firstly, the upper-bound system throughput with determined number of CCs is derived and it is proved by using graph theory that the throughput optimization problem is NP hard. Then we propose a greedy based algorithm to solve this problem and prove that the proposed algorithm can achieve at least 1/2 of the optimal performance in the worst case. At last, we evaluate the throughput and computational complexity performance through a variety of simulations. Simulation results show that the proposed algorithm can obtain better performance comparing with existing schemes while keeping the computation complexity at an acceptable level.

      PubDate: 2016-12-27T11:17:52Z
      DOI: 10.1016/j.phycom.2016.12.002
       
  • Cognitive radio network with secrecy and interference constraints
    • Authors: Hung Tran; Georges Kaddoum; François Gagnon; Louis Sibomana
      Abstract: Publication date: Available online 14 December 2016
      Source:Physical Communication
      Author(s): Hung Tran, Georges Kaddoum, François Gagnon, Louis Sibomana
      In this paper, we investigate the physical-layer security of a secure communication in single-input multiple-output (SIMO) cognitive radio networks (CRNs) in the presence of two eavesdroppers. In particular, both primary user (PU) and secondary user (SU) share the same spectrum, but they face with different eavesdroppers who are equipped with multiple antennas. In order to protect the PU communication from the interference of the SU and the risks of eavesdropping, the SU must have a reasonable adaptive transmission power which is set on the basis of channel state information, interference and security constraints of the PU. Accordingly, an upper bound and lower bound for the SU transmission power are derived. Furthermore, a power allocation policy, which is calculated on the convex combination of the upper and lower bound of the SU transmission power, is proposed. On this basis, we investigate the impact of the PU transmission power and channel mean gains on the security and system performance of the SU. Closed-form expressions for the outage probability, probability of non-zero secrecy capacity, and secrecy outage probability are obtained. Interestingly, our results show that the strong channel mean gain of the PU transmitter to the PU’s eavesdropper in the primary network can enhance the SU performance.

      PubDate: 2016-12-20T06:34:32Z
      DOI: 10.1016/j.phycom.2016.12.001
       
  • Wireless Information-Theoretic Security: Theoretical analysis &
           experimental measurements with multiple eavesdroppers in an outdoor
           obstacle-dense MANET
    • Authors: Theofilos Chrysikos; Konstantinos Birkos; Tasos Dagiuklas; Stavros Kotsopoulos
      Abstract: Publication date: Available online 22 November 2016
      Source:Physical Communication
      Author(s): Theofilos Chrysikos, Konstantinos Birkos, Tasos Dagiuklas, Stavros Kotsopoulos
      Wireless Information-Theoretic Security (WITS) has been suggested as a robust security scheme, especially for infrastructure-less networks. Based on the physical layer, WITS considers quasi-static Rayleigh fading instead of the classic Gaussian wiretap scenario. In this paper, they key parameters of WITS are investigated by implementing an 802.11n ad-hoc network in an outdoor obstacle-dense topology. Measurements performed throughout the topology allow for a realistic evaluation of a scenario with multiple moving eavesdroppers. Low speed user movement has been considered, so that Doppler spread can be discarded. A set of discrete field test trials have been conducted, based on simulation of human mobility throughout an obstacle-constrained environment. Average Signal-to-Noise Ratio (SNR) values have been measured for all moving nodes, and the Probability of Non-Zero Secrecy Capacity has been calculated for different eavesdropping cooperative schemes (Selection Combining and Maximal-Ratio Combining). In addition, the Outage Probability has been estimated with regard to a non-zero target Secrecy Rate for both techniques. The results have been compared with the respective values of WITS key parameters derived from theoretical analysis.

      PubDate: 2016-11-27T23:03:47Z
      DOI: 10.1016/j.phycom.2016.11.003
       
  • Enabling simultaneous cooling and data transmission in the terahertz band
           for board-to-board communications
    • Authors: Vitaly Petrov; Joonas Kokkoniemi; Dmitri Moltchanov; Janne Lehtomäki; Yevgeni Koucheryavy
      Abstract: Publication date: Available online 21 November 2016
      Source:Physical Communication
      Author(s): Vitaly Petrov, Joonas Kokkoniemi, Dmitri Moltchanov, Janne Lehtomäki, Yevgeni Koucheryavy
      A system enabling simultaneous cooling and board-to-board communications is proposed and analyzed. It is shown that hollow pipes used in computer cooling systems can be applied for communications with extreme data rates at distances up to tens of centimeters. This is done by using wireless communications in the terahertz frequency band, 0.1 – 10 THz. The experiments were performed in order to observe how straight and curved pipes of different diameters and lengths affect THz signals propagating inside the pipes. The measured pulses were recorded and used in numerical evaluation of bit error rate and throughput taking into account the effect of all possible combinations of N previous symbols. The numerical results show the dependency of the intersymbol interference on the delay profile of the channel and on the symbol period. The results demonstrate that even with simple on-off keying modulation the throughput reaches few terabits per second with qualitatively low bit error rates. This enables communications between rate-hungry electronics inside computers such as central and graphical processing units while simultaneously providing the cooling functionality.

      PubDate: 2016-11-27T23:03:47Z
      DOI: 10.1016/j.phycom.2016.11.002
       
  • A Cost-effective approach for spectrum sensing using beamforming
    • Authors: Kaïs Bouallegue; Iyad Dayoub; Mohamed Gharbi; Kaïs Hassan
      Abstract: Publication date: Available online 16 November 2016
      Source:Physical Communication
      Author(s): Kaïs Bouallegue, Iyad Dayoub, Mohamed Gharbi, Kaïs Hassan
      Spectrum sensing (SS) is one of the principal challenges on which the mobile communication is based on. Identifying the available frequency bands, also called white spaces, is the main issue. A novel blind approach for SS in the narrowband context is proposed in order to improve the signal detection. Considering a channel with its angle of arrival (AoA), we use beamforming technique to exploit the maximum and minimum angular energy. Both theoretical developments of the threshold and performance analysis are developed. To validate our contribution, the analytical results of the performance developed in this paper are compared with those from simulation. A comparison of state-of-the-art SS method using the eigenvalue decomposition is provided which brings an interesting trade-off between complexity and performance. Finally, simulation results considering the probability of misdetection under very low signal-to-noise ratio (SNR) are presented.

      PubDate: 2016-11-20T21:19:30Z
      DOI: 10.1016/j.phycom.2016.11.001
       
  • Bit error rate analysis of the scheduled TAS with MRC for CR-MIMO systems
    • Authors: Donghun Lee
      Abstract: Publication date: Available online 11 November 2016
      Source:Physical Communication
      Author(s): Donghun Lee
      In this paper, we investigate the bit error rate (BER) analysis of the scheduled transmit antenna selection (TAS) with maximal ratio combining (MRC) for the cognitive radio multiple-input multiple-output (CR-MIMO) systems. As a first step, this paper derives approximate probability density functions (PDFs) of the effective signal to noise ratio (SNR) of the proposed scheduled TAS with MRC in CR-MIMO systems. Next, the tight closed-form expressions of the BER for the M -ary QAM and M -ary PSK modulations are presented, respectively. Using asymptotic analysis, we approximate the BER for the scheduled system, and quantify the diversity order and SNR gain, respectively. Analytical results show that the diversity order of the scheduled system is the product of spatial diversity (SD) and multiuser diversity (MUD). Thus, BER performance of the proposed system is improved as the number of users increases by MUD regardless of modulation types. Also, the SNR gain is getting worsen as the number of received antennas at the primary system increases regardless of modulation types.

      PubDate: 2016-11-13T19:54:10Z
      DOI: 10.1016/j.phycom.2016.10.002
       
  • Adaptive threshold spectrum sensing based on expectation maximization
           algorithm
    • Authors: Daniel Malafaia; Vieira Ana
      Abstract: Publication date: Available online 3 November 2016
      Source:Physical Communication
      Author(s): Daniel Malafaia, José Vieira, Ana Tomé
      In this article we address a novel method for spectrum sensing, based on the Expectation Maximization algorithm applied to the histogram of the moving average signal power. The method enables the estimation of the number of active users in a given frequency band, the power received from each user, the occupied time slots and the front-end noise floor. The proposed approach takes advantage of the statistical properties of the averaging estimator output, which allows to model the received estimated power as a Gaussian mixture. This model represents the distributions of the users transmitted signal power as well as the system noise floor. Moreover, the Gaussian with the lowest mean that is related with the noise floor, can be used to estimate an adaptive threshold for a constant false alarm rate detector. Finally, the method was validated in a Wi-Fi experimental setup, where real-world data was acquired with a software defined radio.

      PubDate: 2016-11-06T17:53:32Z
       
  • OFDM symbol detection integrated with channel multipath gains estimation
           for doubly-selective fading channels
    • Authors: Wang Harry; Leib
      Abstract: Publication date: Available online 2 November 2016
      Source:Physical Communication
      Author(s): Wang Yi, Harry Leib
      Orthogonal Frequency Division Multiplexing (OFDM) is a technique for wideband transmission that is commonly used in modern wireless communication systems because of its good performance over frequency selective channels. However OFDM systems are sensitive to channel time variations resulting in Inter-Carrier Interference (ICI), that without suitable detection methods can degrade performance significantly. Channel State Information (CSI) is essential to various OFDM detection schemes, and its acquisition is a critical factor over time varying channels. This work considers a Kalman filter channel multipath gains estimation technique for time varying environments, integrated with a novel detection scheme for OFDM based on a Sphere Decoding (SD) algorithm derived to exploit the banded structure of the channel matrix. This combined scheme employs decision-feedback from the SD requiring only a low pilot symbol density, and hence improves bandwidth efficiency. Three techniques for integrating the Kalman filter operating in decision-feedback mode, with SD data detection that produces these decisions, are considered in this paper. When compared with other competing schemes, this integrated symbol detection and channel multipath gains estimation approach for OFDM provides performance advantages over time varying channels. Furthermore, it is shown that for moderate Doppler shifts the degradation that carrier phase noise induces in this scheme is small.

      PubDate: 2016-11-06T17:53:32Z
       
  • Spectrum-sharing DF generalized order relay selection with interference
           and multiple primary users using orthogonal spectrums
    • Authors: Anas M. Salhab; Salam A. Zummo
      Abstract: Publication date: Available online 27 October 2016
      Source:Physical Communication
      Author(s): Anas M. Salhab, Salam A. Zummo
      In this paper, we propose and evaluate the performance of cognitive decode-and-forward (DF) generalized order relay selection network where the primary user (PU) receivers utilize orthogonal spectrums in the presence of interference. We consider a new scenario where the primary receivers utilize orthogonal spectrum bands and the spectrum of the primary receiver whose channel enhances the performance of the secondary system is shared with the secondary user (SU) nodes. Using orthogonal spectrum bands in cellular networks aims to reduce the interference between users as in the downlink transmission where orthogonal frequency bands are used by the base station (BS) in transmitting the data for the different users. The generalized order relay selection scheme is efficient in situations where the opportunistic relaying scheme could fail such as in conditions of imperfect channel-state-information, outdated channel information, and in cases where the best relay is busy in some scheduling and load balancing duties in other parts of the network. Closed-from expression is derived for the end-to-end (e2e) outage probability assuming Rayleigh fading channels. Furthermore, to get more insights about the system behavior, the performance is studied at the high signal-to-noise ratio (SNR) regime where the diversity order and coding gain are derived. Monte-Carlo simulations are given to verify the achieved results. The main results show that the number of primary receivers affects the system performance through affecting the coding gain and not the diversity order. Unlike the existing papers where the same spectrum band is assumed to be shared by the primary receivers with the secondary users, our findings demonstrate that increasing the number of primary receivers in the proposed scenario enhances the system performance. Finally, results illustrate that when the interference at the secondary relays or destination or at both scales with SNR, the system achieves a zero diversity order and a noise floor appears in the results due to the effect of interference on the system performance.

      PubDate: 2016-10-30T14:41:38Z
      DOI: 10.1016/j.phycom.2016.10.001
       
  • Power allocation for cognitive underlay networks with spectrum band
           selection
    • Authors: Hung Tran; Georges Kaddoum; François Gagnon
      Abstract: Publication date: Available online 5 October 2016
      Source:Physical Communication
      Author(s): Hung Tran, Georges Kaddoum, François Gagnon
      In this paper, we study the cooperative communication of a cognitive underlay network by utilizing the diversity of multiple spectrum bands. In particular, we assume that the transmission power of the secondary user (SU) is subject to different joint constraints, such as peak interference power of the multiple primary users (PUs), peak transmission power of the SU, outage tolerate interference, and outage probability threshold. Accordingly, two power allocation schemes are considered on the basis of the minimum interference channel from the SU to the PU and the channel state information of the primary user link. Furthermore, the SU can select one of the three transmission modes following the channel state conditions, namely as cellular, device-to-device, or switching mode, to transmit the signal to the secondary user receiver. Given this setting, two power allocation schemes over a spectrum band selection strategy are derived. In addition, closed-form expressions for the outage probability of three modes are also obtained to evaluate the performance of the secondary network. Most importantly, a closed-form expression for the peak interference power level of the PU, which is considered as one of the most important parameters to control the SU’s transmission power, is derived by investigating the relation of two considered power allocation schemes in the practise. Finally, numerical examples show that the outage performance of secondary network in the switching mode outperforms the one of the cellular and device-to-device (D2D) mode for all considered power allocation schemes.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.09.004
       
  • Cyclic feature suppression for physical layer security
    • Authors: Z. Esat Ankaralı; Hüseyin Arslan
      Abstract: Publication date: Available online 22 September 2016
      Source:Physical Communication
      Author(s): Z. Esat Ankaralı, Hüseyin Arslan
      Cyclic prefix (CP) deploying techniques such as orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) offer considerable advantages in terms of equalizing time dispersive effect of wireless channel at the expense of a reasonable spectral redundancy. However, CP introduces cyclic features to the signal which can also be exploited for signal interception, blind parameter estimation and synchronization, and therefore, compromises the security of the signal against eavesdropping attacks. In order to provide a covert communication against such attacks, in this paper, we present two novel techniques that suppress the cyclic features of the CP utilizing signals while maintaining their advantages in equalization without reducing spectral efficiency. The first technique is built on a CP selection strategy while the second one is based on randomizing the symbol time. We also performed peak-to-average power ratio mitigation and out-of-band leakage suppression along with the cyclic feature concealing in the second technique at the expense of a reasonable complexity and signaling. Subsequent to the presentation of the proposed techniques, their performances are discussed and compared for OFDM and SC-FDE in terms of complexity and bit-error-rate along with cyclic feature suppression. 1 1 A part of this study is presented in IEEE Military Communication Conference (MILCOM), 2014.

      PubDate: 2016-10-16T08:58:51Z
      DOI: 10.1016/j.phycom.2016.09.003
       
  • Secure degrees of freedom in cooperative K-helper MIMO cognitive radio
           systems
    • Authors: Hua Ping; Jitendra Tugnait
      Abstract: Publication date: Available online 21 September 2016
      Source:Physical Communication
      Author(s): Hua Mu, Ping Lu, Jitendra K. Tugnait
      We study the achievable secure degrees of freedom (DoF) in a cooperative MIMO cognitive radio system comprised of one primary source–destination pair, multiple secondary source–destination pairs and an eavesdropper against whom the primary user intends to secure its data. In this system, multiple secondary user pairs help to secure primary user’s data against eavesdropping. In return, these secondary users are allowed to access primary user’s spectrum. All users, including primary user pair, K ≥ 2 secondary user pairs and the eavesdropper are equipped with M antennas. We investigate the secure DoF without the knowledge of eavesdropper’s channel state information (CSI), using the interference alignment concept combined with a zero inter-user interference constraint. A beamforming design is proposed to achieve secure DoF d for the primary user and DoF d for all secondary users if K d ≤ M . The case of untrusted secondary users is also investigated where the secondary users may potentially eavesdrop. Simulation examples corroborating the theoretical results are presented.

      PubDate: 2016-10-16T08:58:51Z
       
  • Algebraic soft decoding of Reed-Solomon codes with improved progressive
           interpolation
    • Authors: Lyu Chen
      Abstract: Publication date: Available online 10 June 2016
      Source:Physical Communication
      Author(s): Lyu Yi, Chen Li
      The algebraic soft decoding (ASD) algorithm for Reed-Solomon (RS) codes can correct errors beyond the half distance bound with a polynomial time complexity. However, the decoding complexity remains high due to the computationally expensive interpolation that is an iterative polynomial construction process. By performing the interpolation progressively, the progressive ASD (PASD) algorithm can adapt the decoding computation to the need, leveraging the average complexity of multiple decoding events. But the complexity reduction is realised at the expense of system memory, since the intermediate interpolation information needs to be memorised. Addressing this challenge, this paper proposes an improved PASD (I-PASD) algorithm that can alleviate the memory requirement and further reduce the decoding complexity. A condition on expanding the set of interpolated polynomials will be introduced, which excepts the need of performing iterative updates for the newly introduced polynomial. Further incorporating the re-encoding transform, the I-PASD algorithm can reduce the decoding complexity over the PASD algorithm by a factor of 1 / 3 and its memory requirement is at most half of the PASD algorithm. The complexity and memory requirement will be theoretically analysed and validated by numerical results. Finally, we will confirm that the complexity and memory reductions are realised with preserving the error-correction capability of the ASD algorithm.

      PubDate: 2016-06-16T18:20:32Z
       
 
 
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