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PHYSICS (576 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  [3043 journals]
  • Cost-efficient secondary users grouping for two-tier cognitive radio
    • Authors: Yousef N. Shnaiwer; Salam A. Zummo; Wessam Mesbah; Saad Al Ahmadi
      Pages: 1 - 13
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 1
      Author(s): Yousef N. Shnaiwer, Salam A. Zummo, Wessam Mesbah, Saad Al Ahmadi
      In this paper, a novel GPS-assisted grouping scheme is proposed to reduce the operational cost of cognitive radio networks with femtocells. This scheme allows the cognitive base station (CBS) to determine the minimum number of channels to be rented from the primary user (PU) networks by utilizing greedy graph coloring and frequency re-use. The proposed scheme is optimized, in terms of the distances between the FBSs in the same group, and extended to the co-channel deployment case (i.e., when the macrocell secondary users (MSUs) and the FBSs are operating on the same spectrum band). Moreover, the performance of the scheme is analyzed in terms of the average number of CBS channels, average outage probability, and complexity. Furthermore, two benchmark schemes are devised and compared to the distance-based greedy coloring scheme; namely, the optimal distance-based and the profit maximization schemes. Simulation results show that the performance of the distance-based greedy coloring scheme, in terms of reducing the number of channels to be purchased from the PU networks, approaches that of the optimal scheme in high interference environments.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.006
      Issue No: Vol. 25 (2017)
  • On physical-layer concepts and metrics in secure signal transmission
    • Authors: Ertuğrul Güvenkaya; Jehad M. Hamamreh; Hüseyin Arslan
      Pages: 14 - 25
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 1
      Author(s): Ertuğrul Güvenkaya, Jehad M. Hamamreh, Hüseyin Arslan
      Communication secrecy in the wireless systems has unique challenges due to broadcasting nature of the radio waves, as compared to its wire-line counterpart. At the same time, different and independent perceptions of the transmitted signal by the legitimate receiver and the eavesdropper provide new opportunities for secure communication. The distinctness in the physical propagation environment, e.g., in received power, wireless channel, and location of the legitimate and illegitimate nodes, when coupled with random and unique signatures, can be exploited for secure communication without using secret keys. In this paper, fundamental stages as well as requirements of the physical layer (PHY) security in information transmission are reviewed from a novel perspective. Then, main performance metrics in secure communication are surveyed including from information theoretic measures to practical considerations along with associated generalizations. The presented comprehensive viewpoint of PHY security stages and metrics is helpful to better understand the techniques exploiting the physics to secure the information in the lowest layer of the communication system.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.011
      Issue No: Vol. 25 (2017)
  • An efficient network coding scheme for reliable multicast power line
    • Authors: Francesco Chiti; Romano Fantacci; Andrea Tani
      Pages: 34 - 42
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 1
      Author(s): Francesco Chiti, Romano Fantacci, Andrea Tani
      Nowadays, Power Line Communication (PLC) technology is receiving a renewed attention for a wide class of innovative applications and services, mainly thanks to the advantage of using the existing electrical infrastructures, thus reducing the deployment costs. However, such electrical infrastructures have been originally conceived for power distribution and not for data. Hence, signal propagation is affected by more severe impairments than traditional media, such as impulsive noise and frequency selectivity. Furthermore, new emerging PLC applications need more efficient information delivery schemes that encompass both unicast and multicast mode. Towards this end, this paper deals with an efficient Network Coding (NC) based multicast reliable PLC scheme that makes use of (i) a decision direct impulsive noise mitigation approach and of (ii) a scheme based on multiple transmissions of a same symbols in the frequency domain. A suitable optimization procedure is also proposed here with the aim of improving the performance of the proposed scheme, under the constraint of a specified maximum data flow delivery failure probability. Finally, comparisons with alternative solutions are provided in order to highlight the significant advantages of the proposed scheme in terms of data flow delivery delay and overall transmission energy cost, under specific service constraints.

      PubDate: 2017-09-15T12:10:16Z
      DOI: 10.1016/j.phycom.2017.08.017
      Issue No: Vol. 25 (2017)
  • Spectrum mobility in cognitive radio network using spectrum prediction and
           monitoring techniques
    • Authors: Prabhat Thakur; Alok Kumar; S. Pandit; G. Singh; S.N. Satashia
      Pages: 1 - 8
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Prabhat Thakur, Alok Kumar, S. Pandit, G. Singh, S.N. Satashia
      The spectrum mobility during data transmission is an integral part of the cognitive radio network (CRN) which is conventionally two types for instance reactive and proactive. In the reactive approach, the cognitive user (CU) switches its communication after the emergence of the primary user (PU), where the detection of emergence of PU relies either on spectrum sensing and/or monitoring. Due to certain limitations of the reactive approach such as: (1) loss at least one packet on the emergence of PU and (2) resource (bandwidth) wastage if the periodic sensing is used for mobility, the researchers have introduced the concept of proactive spectrum mobility. In this approach, the emergence of PU is predicted on the bases of pre-available spectrum information, and switching is performed before true emergence of the PU, in order to avoid even the single packet loss. However, the imperfect spectrum prediction is a major milestone for the proactive spectrum mobility. Recently, due to introduction of the spectrum monitoring simultaneous to the data transmission, the reactive approach has come into lime-light again, however, it suffers from the ‘single packet loss’ and ‘imperfect spectrum monitoring’ issues. Therefore in this paper, we have exploited the spectrum monitoring and prediction techniques, simultaneously for the spectrum mobility, in order to enhance the performance of cognitive radio network (CRN). In the proposed strategy, the decision results of the spectrum prediction and monitoring techniques are fused using AND and OR fusion rules, for the detection of emergence of PU during the data transmission. Further, the closed-form expressions of the resource wastage, achieved throughput, interference power at PU and data-loss for the proposed approaches as well as for the prediction and monitoring approaches are derived. Moreover, the simulation results for the proposed approaches are presented and validation is performed by comparing the results with prediction and monitoring approach. In a special case, when the prediction error is zero, the graphs of all metric values overlies the spectrum monitoring approach, which further validates the proposed approach.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.04.005
      Issue No: Vol. 24 (2017)
  • Proportional fairness analysis of massive MIMO Two-tier multiuser downlink
           with subchannel pairing
    • Authors: Irfan Ahmed
      Pages: 9 - 18
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Irfan Ahmed
      This paper presents a proportional fairness throughput analysis of a millimeter wave massive multiple-input multiple output (MIMO) small base station (SBS)-assisted downlink with subchannel (SC) pairing. We derive an analytical expression for evaluating the average logarithmic throughput with SC-pairing and proportional fairness in two-tier network with amplify-and-forward (AF) and decode-and-forward (DF) SBSs. Analytical expressions are derived for the probability density function (PDF) of logarithmic throughput, and the average logarithmic throughput with statistical channel state information (CSI) based gain at AF SBS. It has been shown that the percentage error between simulation and analytical results decreases with increase in number of SC N and number of antennas, and is upper bounded by 0.28% and 0.79% when N ≥ 16 for AF and DF SBSs, respectively.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.05.001
      Issue No: Vol. 24 (2017)
  • A spectrum handoff scheme for optimal network selection in Cognitive Radio
           vehicular networks: A game theoretic auction theory approach
    • Authors: Krishan Kumar; Arun Prakash; Rajeev Tripathi
      Pages: 19 - 33
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Krishan Kumar, Arun Prakash, Rajeev Tripathi
      The recent strides in vehicular networks have emerged as a convergence of multi radio access networks having different user preferences, multiple application requirements and multiple device types. In future Cognitive Radio (CR) vehicular networks deployment, multiple radio access networks may coexist in the overlapping areas having different characteristics in terms of multiple attributes. Hence, it becomes a challenge for CR vehicular node to select the optimal network for the spectrum handoff decision. A game theoretic auction theory approach is interdisciplinary effective approach to select the optimal network for spectrum handoff. The competition between different CR vehicular node and access networks can be formulated as multi-bidder bidding to provide its services to CR vehicular node. The game theory is the branch of applied mathematics which make intelligent decision to select the optimal alternative from predetermined alternatives. Hence, this paper investigates a spectrum handoff scheme for optimal network selection using game theoretic auction theory approach in CR vehicular networks. The paper has also proposed a new cost function based multiple attribute decision making method which outperforms other existing methods. Numerical results revel that the proposed scheme is effective for spectrum handoff for optimal network selection among multiple available networks.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.04.001
      Issue No: Vol. 24 (2017)
  • Modeling the lossy transmission of correlated sources in multiple access
           fading channels
    • Authors: Antonios Argyriou; Özgü Alay; Panagiotis Palantas
      Pages: 34 - 45
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Antonios Argyriou, Özgü Alay, Panagiotis Palantas
      In this paper, we develop accurate distortion models for the lossy transmission of two correlated sources in a multiple access Rayleigh fading channel. We focus on a class of real-life communication systems, where the source and channel coders have already been designed separately and can only be configured during the system operation. We investigate three different source coding schemes: distributed source coding (DSC), layered source coding, and independent compression through quantization. With the later scheme the sources are jointly decoded with minimum mean square error (MMSE) estimation at the receiver. We also consider two different transmission schemes: Orthogonal transmissions and interfering transmissions decoded with a successive interference cancellation (SIC) decoder. Our final closed-form analytical models are used to determine the optimal combination of source coding and transmission schemes, as well as their optimal configuration. Hence, we exercise joint source and channel coding (JSCC) by optimizing the system configuration. Through simulations, we first validate the analytical model and illustrate the performance of different schemes. Finally, we demonstrate the JSCC gains achieved by our system.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.05.003
      Issue No: Vol. 24 (2017)
  • Waveform contenders for 5G: Description, analysis and comparison
    • Authors: Jean-Baptiste Doré; Robin Gerzaguet; Nicolas Cassiau; Dimitri Ktenas
      Pages: 46 - 61
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Jean-Baptiste Doré, Robin Gerzaguet, Nicolas Cassiau, Dimitri Ktenas
      5G will have to cope with a high degree of heterogeneity in terms of services and requirements. Among these latter, flexible and efficient use of all available non-contiguous spectra for different network deployment scenarios is one challenge for the future 5G. To maximize spectrum efficiency, a flexible 5G air interface technology capable of mapping various services to the best suitable combinations of frequency and radio resources will also be required. In this work, a fair comparison of several 5G waveform candidates (UFMC, FBMC-OQAM, and FBMC-QAM) is proposed under a common framework. Spectral efficiency, power spectral density, peak to average power ratio and performance in terms of bit error rate under various realistic channel conditions are assessed. The waveforms are then compared in an asynchronous multi-user uplink transmission. Based on these results, in order to increase the spectral efficiency, a bit loading algorithm is proposed to cope with the non-uniform distribution of the interference across the carriers. The benefits of these new waveforms for the foreseen 5G use cases are clearly highlighted. It is also stressed that some concepts still need to be improved to achieve the full range of expected benefits of 5G.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.05.004
      Issue No: Vol. 24 (2017)
  • High SNR approximation for performance analysis of two-way multiple relay
    • Authors: Muhammad I. Khalil; Stevan M. Berber; Kevin W. Sowerby
      Pages: 62 - 70
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Muhammad I. Khalil, Stevan M. Berber, Kevin W. Sowerby
      Signal-to-Noise Ratio (SNR) is the key parameter in the performance evaluation of Two-Way, Amplify-and-Forward, Multiple-Relaying (TAF-MR) networks. This paper introduces new methods that use high SNR (HSNR) level approximations to analyze accurately the Bit Error Rate (BER), optimize the Relay Location (RL), and balance the energy efficiency (EE) and spectral efficiency (SE) of such networks. We consider a flat-fading channel and a strategy for selecting a relay with the highest SNR. Standardized BER expressions are obtained for a wide range of SNRs (low, high, and optimal) to yield more accurate predictions of the BER performance. Thus, by using HSNR, a unified analysis for calculating the Asymptotic BER (ABER) and the exact BER (EBER) performance is developed. The optimal SNR level is obtained by optimizing the power of network sources, which include the relay and user powers. Further, we propose a method for integrating the RL with the balancing of the EE and SE optimally to achieve the best EE improvement. The derived expressions for the methods are validated by simulation.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.04.007
      Issue No: Vol. 24 (2017)
  • Power efficient and coordinated eICIC-CPC-ABS method for downlink in
           LTE-advanced heterogeneous networks
    • Authors: Srinivasa Rao K.; Vinay Kumar; Sudhir Kumar; Sadanand Yadav; Vinay Kumar Ancha; Rajeev Tripathi
      Pages: 71 - 82
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Srinivasa Rao K., Vinay Kumar, Sudhir Kumar, Sadanand Yadav, Vinay Kumar Ancha, Rajeev Tripathi
      In 2020, mobile data traffic is expected to be a thousand times more than the current scenario. In order to handle this increased capacity, improvement in spectral efficiency is one of the challenging task. In long term evolution (LTE) and long term evolution advanced (LTE-A), deployment of small cell base station (SBS) and hotspot are step to handle the increased capacity of the network and quality of service. In this scenario, the SBSs are deployed under the coverage of macro cell base station (MBS). Neighbour MBS and neighbour SBS create intra and inter-cell interference to the users in the overlapped region. In order to mitigate interference, coordination between base stations is required. In this paper, we propose an enhanced intercell interference coordination by considering centralized processing controller with almost blank subframe (eICIC-CPC-ABS) for heterogeneous networks (HetNets). Centralized processing controller (CPC) at MBS decides the radio resource allocation of each SBSs based on user location. The dynamic frequency and reduced transmission power depend on the user locations. The analytical and simulation results demonstrate that the proposed method (eICIC-CPC-ABS) provides higher signal to interference plus noise ratio (SINR) compared to existing models: inter cell interference coordination (ICIC) and enhanced inter cell interference coordination (eICIC). The proposed method provides significant savings in transmitting power. Additionally, it increases the network capacity and coverage.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.05.002
      Issue No: Vol. 24 (2017)
  • Adaptive and efficient nonlinear channel equalization for underwater
           acoustic communication
    • Authors: Dariush Kari; Nuri Denizcan Vanli; Suleyman S. Kozat
      Pages: 83 - 93
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Dariush Kari, Nuri Denizcan Vanli, Suleyman S. Kozat
      We investigate underwater acoustic (UWA) channel equalization and introduce hierarchical and adaptive nonlinear (piecewise linear) channel equalization algorithms that are highly efficient and provide significantly improved bit error rate (BER) performance. Due to the high complexity of conventional nonlinear equalizers and poor performance of linear ones, to equalize highly difficult underwater acoustic channels, we employ piecewise linear equalizers. However, in order to achieve the performance of the best piecewise linear model, we use a tree structure to hierarchically partition the space of the received signal. Furthermore, the equalization algorithm should be completely adaptive, since due to the highly non-stationary nature of the underwater medium, the optimal mean squared error (MSE) equalizer as well as the best piecewise linear equalizer changes in time. To this end, we introduce an adaptive piecewise linear equalization algorithm that not only adapts the linear equalizer at each region but also learns the complete hierarchical structure with a computational complexity only polynomial in the number of nodes of the tree. Furthermore, our algorithm is constructed to directly minimize the final squared error without introducing any ad-hoc parameters. We demonstrate the performance of our algorithms through highly realistic experiments performed on practical field data as well as accurately simulated underwater acoustic channels.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.06.001
      Issue No: Vol. 24 (2017)
  • Performance of lattice coset codes on Universal Software Radio Peripherals
    • Authors: Jinlong Lu; J. Harshan; Frédérique Oggier
      Pages: 94 - 102
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Jinlong Lu, J. Harshan, Frédérique Oggier
      We consider an experimental setup of three Universal Software Radio Peripherals (USRPs) that implement a wiretap channel, two USRPs are the legitimate players Alice and Bob, while the third USRP is the eavesdropper, whose position we vary to evaluate information leakage. The experimented channels are close to slow fading channels, and coset coding of lattice constellations is used for transmission, allowing to introduce controlled randomness at the transmitter. Simulation and measurement results show to which extent coset coding can provide confidentiality, as a function of Eve’s position, and the amount of randomness used.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.04.004
      Issue No: Vol. 24 (2017)
  • Decode-and-forward with quadrature spatial modulation in the presence of
           imperfect channel estimation
    • Authors: Raed Mesleh; Salama S. Ikki; Iyad Tumar; Sahel Alouneh
      Pages: 103 - 111
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Raed Mesleh, Salama S. Ikki, Iyad Tumar, Sahel Alouneh
      The performance of quadrature spatial modulation (QSM) multiple-input multiple-output (MIMO) system with cooperative decode and forward (DF) relays is analyzed in this paper. QSM is a new MIMO transmission technique that enhances the overall performance of conventional spatial modulation through exploiting quadrature spatial dimension. A practical scenario is considered where the channel is estimated at the relays and the destination and the impact of channel estimation error is investigated. Two cooperative systems are considered in the study. In the first system, multiple single-antenna DF relays are assumed, whereas, in the second system, single multiple-antennas DF relay is considered. For both systems, an analytical expression for the pair wise error probability (PEP) is obtained. As well, an asymptotic expression for the PEP at high and pragmatic signal to noise ratio is derived. Derived expressions are used to provide an upper bound on the average bit error ratio. The derived analysis is corroborated through Monte Carlo simulations and results demonstrate a close-match for a wide range of SNR values.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.06.005
      Issue No: Vol. 24 (2017)
  • Channel resource allocation and availability prediction in hybrid access
    • Authors: Muhammad Rehan Usman; Muhammad Arslan Usman; Soo Young Shin
      Pages: 112 - 122
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): Muhammad Rehan Usman, Muhammad Arslan Usman, Soo Young Shin
      In this paper, three channel assignment models are proposed for channel resource allocation in femtocells. The models proposed are based on the Markov chain process. According to the access mechanisms in femtocells, the Third-Generation Partnership Project (3GPP) has described two kinds of users in the femtocell application; open users and the closed subscriber group (CSG). In hybrid access mechanism for femtocells, both CSG users and open users are usually referred as subscribers and non-subscribers respectively. So, in this work, for all the proposed models, the CSG and open users are categorized into two groups; the subscriber group (SG) and the non-subscriber group (NSG) respectively. The proposed models provide priority based channel resource allocation strategies between the SG and NSG. Furthermore, the focus of this research is to provide variable channel resource sharing among the SG and NSG to keep the wastage of channel resources minimum for better quality of service (QoS). The analysis is conducted in terms of channel resource blocking management for all the models and to validate the analysis, simulations are performed at the end of this paper. Further, channel resource blocking prediction, based on the blocking probability results for SG and NSG users, is also provided at the end. The prediction is done through risk analysis using the @ Risk tool. The simulations are provided in two parts; 1) the probability curves for SG and NSG against the total number of channels and 2) the risk analysis results for blocked channels prediction using the @ Risk tool.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.06.007
      Issue No: Vol. 24 (2017)
  • On the SINR statistics of a VFDM cognitive spectrum sharing system
    • Authors: K. Denia Kanellopoulou; Kostas P. Peppas; P. Takis Mathiopoulos
      Pages: 195 - 200
      Abstract: Publication date: September 2017
      Source:Physical Communication, Volume 24
      Author(s): K. Denia Kanellopoulou, Kostas P. Peppas, P. Takis Mathiopoulos
      An analytical precise approximation of the SINR statistics of the two-tier Vandermonde-subspace frequency division multiplexing (VFDM) cognitive spectrum sharing systems over frequency-selective Rayleigh fading channels is presented. It is shown that the gamma distribution provides the best fitting accuracy and that its use leads to simple, yet accurate, closed-form expressions for evaluating the ergodic capacity (EC) and average bit error probability (ABEP) performance of such systems. In deriving these expressions, the parameters of the gamma distribution have been obtained for various operating conditions of the considered VFDM system using distribution fitting. Furthermore, regression analysis has been used to obtain approximate analytical expressions for these parameters in relation to the system operating parameters. Performance evaluation results, obtained for various system implementations, including the standardized IEEE 802.11 and 3GPP LTE, are presented to demonstrate the validity of the proposed methodology. Its accuracy has been verified by means of computer simulations.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.07.004
      Issue No: Vol. 24 (2017)
  • Bandwidth allocation-based simultaneous cooperative spectrum sensing and
           energy harvesting for multicarrier cognitive radio
    • Authors: Xin Liu; Dongyue He; Weidang Lu; Feng Li
      Abstract: Publication date: Available online 16 October 2017
      Source:Physical Communication
      Author(s): Xin Liu, Dongyue He, Weidang Lu, Feng Li
      In cognitive radio (CR), a secondary user (SU) may consume more energy due to spectrum sensing. In order to guarantee transmission performance of the SU, a bandwidth allocation-based simultaneous cooperative spectrum sensing and energy harvesting for multicarrier CR is proposed, which can collect the radio frequency (RF) energy of the wireless signal from primary user (PU) to supply the consumed sensing energy. Each subcarrier is split into spectrum sensing bandwidth, energy harvesting bandwidth and transmission bandwidth, thus cooperative spectrum sensing, energy harvesting and data transmission can be implemented simultaneously within transmission time. Multicarrier cooperative spectrum sensing is proposed to improve sensing performance and decrease cooperative overhead through combining the sensing results from all the subcarriers. A joint optimization problem has been formulated to achieve the maximal throughput of the SU by jointly optimizing sensing bandwidth ratio and subcarrier power. Simulation results have shown that there exists an optimal sensing bandwidth that maximizes the throughput and the performance of the proposed model is predominant.

      PubDate: 2017-10-19T02:46:45Z
      DOI: 10.1016/j.phycom.2017.10.002
  • Interference mitigation in multiuser communication by faster than symbol
           rate sampling
    • Authors: Eren Balevi; A. Özgür Yılmaz
      Abstract: Publication date: Available online 16 October 2017
      Source:Physical Communication
      Author(s): Eren Balevi, A. Özgür Yılmaz
      The degrees of freedom (DoF) gain due to excess bandwidth is lost in case of Symbol Rate (SR) sampling where Faster than Symbol Rate (FTSR) sampling emerges as a promising approach to exploit this gain. In this direction, FTSR sampling is studied to increase the total number of users in a network for a given fixed bandwidth. The rank analysis indicates that FTSR sampling brings rank advantage proportional to the excess bandwidth for unequally spaced channel taps. With the help of an iterative FTSR sampled MMSE multiuser receiver, this rank advantage can be employed in the separation of two users’ signals from each other that transmit simultaneously on the same frequency band.

      PubDate: 2017-10-19T02:46:45Z
      DOI: 10.1016/j.phycom.2017.10.001
  • A bandwidth efficient selective mapping technique for the PAPR reduction
           in spatial multiplexing MIMO-OFDM wireless communication system
    • Authors: A.S. Namitha; S.M. Sameer
      Abstract: Publication date: Available online 27 September 2017
      Source:Physical Communication
      Author(s): A.S. Namitha, S.M. Sameer
      An inherent issue of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technique is its high peak-to-average power ratio (PAPR) over distinct antennas. Selective mapping (SLM) is one of the most prevalent methods to reduce the PAPR without inducing any signal deformation in OFDM or MIMO-OFDM. The main drawback of the SLM technique is the need for sending side information (SI) with each OFDM data symbol for retrieving the transmitted data. In this paper, we present a low complexity SLM technique using Hadamard sequence to substantially reduce the PAPR in MIMO-OFDM systems without the need for transmitting SI thus resulting in improved data rate/ bandwidth efficiency and BER performance. Simulation studies show that the proposed method achieves a significant reduction in PAPR and improves the BER performance as compared to some prevailing methods.

      PubDate: 2017-10-04T19:28:05Z
      DOI: 10.1016/j.phycom.2017.09.009
  • Estimation of channel and Carrier Frequency Offset in OFDM systems using
           joint statistical framework
    • Authors: Renu Jose
      Abstract: Publication date: Available online 22 September 2017
      Source:Physical Communication
      Author(s): Renu Jose
      Joint estimation of channel and Carrier Frequency Offset (CFO) in Orthogonal Frequency Division Multiplexing (OFDM) systems, using a Statistical framework, is shown in this paper. Hybrid Cramér-Rao Lower Bounds (HCRLBs) for the estimation of CFO together with the channel are obtained. The significance of prior information in the formulation of a joint estimator is shown by comparing HCRLB with the corresponding standard CRLB. We propose a Joint Maximum a posteriori (JMAP) algorithm for the estimation of channel and CFO in OFDM, utilizing the prior statistical knowledge of channel. To reduce the complexity of JMAP estimator, a Modified JMAP (MJMAP) algorithm, which has no grid searches, is also proposed. The estimation methods are analyzed by numerical simulations and resultant conclusions validate the better performance of the proposed algorithms when compared with previous algorithms.

      PubDate: 2017-09-27T16:13:37Z
      DOI: 10.1016/j.phycom.2017.09.007
  • Cluster-head based feedback for simplified time reversal prefiltering in
           ultra-wideband systems
    • Authors: Hossein Soleimani; Stefano Tomasin; Tohid Alizadeh; Mohammad Shojafar
      Abstract: Publication date: Available online 21 September 2017
      Source:Physical Communication
      Author(s): Hossein Soleimani, Stefano Tomasin, Tohid Alizadeh, Mohammad Shojafar
      Time-reversal prefiltering (TRP) technique for impulse radio (IR) ultra wide-band (UWB) systems requires a large amount of feedback to transmit the channel impulse response from the receiver to the transmitter. In this paper, we propose a new feedback design based on vector quantization. We use a machine learning algorithm to cluster the estimated channels into several groups and to select the channel cluster heads (CCHs) for feedback. In particular, CCHs and their labels are recorded at both side of the UWB transceivers and the label of the most similar CCH to the estimated channel is fed back to the transmitter. Finally, the TRP is applied using the feedback CCH. The proposed digital feedback provides three main advantages: (1) it significantly reduces the dedicated bandwidth required for feedback; (2) it considerably improves the speed of transceivers; and, (3) it is robust to noise in the feedback channel since few bytes are required to send the codes that can be heavily error protected. Numerical results on standard UWB channel models are discussed, showing the advantage of the proposed solution.

      PubDate: 2017-09-27T16:13:37Z
      DOI: 10.1016/j.phycom.2017.09.005
  • Interference suppression algorithm based R-TDD for multi-user MIMO
           heterogeneous network
    • Authors: Yu Li; Zufan Zhang
      Abstract: Publication date: Available online 20 September 2017
      Source:Physical Communication
      Author(s): Yu Li, Zufan Zhang
      Aiming at the problem of uplink co-channel interference in multi-user multi-input multi-output (MIMO) heterogeneous network, a reversed time division duplex (R-TDD)-based method is used to improve the performance of interference rejection combing (IRC) algorithm. This method overcomes the difficulty of IRC algorithm in obtaining the interference noise covariance matrix by utilizing the R-TDD transmission scheme. On the premise that the spectrum efficiency is guaranteed, through combining R-TDD with spatial modulation, the transmission complexity is significantly reduced and the uplink co-channel interference is effectively controlled, so as to improve the system performance. Simulation results demonstrate that the R-TDD-based scheme can improve the performance of IRC algorithm in terms of spectrum efficiency.

      PubDate: 2017-09-20T13:48:33Z
      DOI: 10.1016/j.phycom.2017.08.016
  • On the outage analysis of a D2D network with uniform node distribution in
           a circular region
    • Authors: Rafay Iqbal Ansari; Syed Ali Hassan; Sajid Ali; Chrysostomos Chrysostomou; Marios Lestas
      Abstract: Publication date: Available online 20 September 2017
      Source:Physical Communication
      Author(s): Rafay Iqbal Ansari, Syed Ali Hassan, Sajid Ali, Chrysostomos Chrysostomou, Marios Lestas
      This paper studies the coverage probability of a device-to-device (D2D) link between a pair of nodes uniformly distributed in a circular region of arbitrary radius, thereby modeling the D2D network operation for a public safety scenario. The expression for the cumulative distribution function (CDF) of the signal-to-interference ratio (SIR) at the destination is derived, where the transmissions are affected by multipath fading, path loss and interference. The analysis involves finding the ratio distribution of two random variables, representing the desired signal and the intra-region interference, respectively. The expression for CDF helps in ascertaining the outage probability at the destination. Hence, given a desired outage probability, a limit on the number of simultaneously active D2D links in a circular region can be determined, thereby allowing interference avoidance. Numerical simulations are conducted to validate the theoretical model. The Kolmogorov–Smirnov (K-S) test is applied to further characterize the matching between simulation and analytical model. Moreover, the results also help in identifying the minimum transmit power that ensures the desired quality-of-service (QoS), providing efficient transmission in energy constrained environments.

      PubDate: 2017-09-20T13:48:33Z
      DOI: 10.1016/j.phycom.2017.09.006
  • Unsupervised feature learning and automatic modulation classification
           using deep learning model
    • Authors: Afan Ali; Fan Yangyu
      Abstract: Publication date: Available online 18 September 2017
      Source:Physical Communication
      Author(s): Afan Ali, Fan Yangyu
      Recently, deep learning has received a lot of attention in many machine learning applications for its superior classification performance in speech recognition, natural language understanding and image processing. However, it still lacks attention in automatic modulation classification (AMC) until now. Here, we introduce the application of deep learning in AMC. We propose a fully connected 2 layer feed-forward deep neural network (DNN) with layerwise unsupervised pretraining for the classification of digitally modulated signals in various channel conditions. The system uses independent autoencoders (AEs) for feature learning with multiple hidden nodes. Signal information from the received samples is extracted and preprocessed via I and Q components, and formed into training input to 1st AE layer. A probabilistic based method is employed at the output layer to detect the correct modulation signal. Simulation results show that a significant improvement can be achieved compared to the other conventional machine learning methods in the literature. Moreover, we also show that our proposed method can extract the features from cyclic-stationary data samples. A good classification accuracy was achieved, even when the proposed deep network is trained and tested at different SNRs. This shows the future potential of the deep learning model for application to AMC.

      PubDate: 2017-09-20T13:48:33Z
      DOI: 10.1016/j.phycom.2017.09.004
  • A Dynamic Inter-cellular Bandwidth Fair Sharing scheduler for future
           wireless networks
    • Authors: Mahdi Ezzaouia; Cédric Gueguen; Mahmoud Ammar; Sébastien Baey; Xavier Lagrange; Ammar Bouallegue
      Abstract: Publication date: Available online 14 September 2017
      Source:Physical Communication
      Author(s): Mahdi Ezzaouia, Cédric Gueguen, Mahmoud Ammar, Sébastien Baey, Xavier Lagrange, Ammar Bouallegue
      Due the limitation of the frequency spectrum, channel assignment remains a main challenge in future wireless networks. In this context, the Inter-cellular Scheduling Scheme consists in dynamically allocating/reallocating the bandwidth to the cells, adapting it to the inhomogeneous traffic distribution that appears in a multi-cell environment. More precisely, it dynamically selects the cell that experiences the highest difficulties and grants it supplementary radio resources borrowed from its neighboring under-loaded donor ones. In this paper, we introduce and explain the concept of minimal bandwidth, which corresponds to the minimal amount of radio resources that an under-loaded cell must keep in order to be protected from sudden and uneven high bit rates peaks. This minimal bandwidth guarantees a minimal service. The majority of the existing works on dynamic channel assignment neglects the use of this important parameter or consider it as a static one. In this context, we introduce a novel multicellular scheduler called Dynamic Inter-cellular Bandwidth Fair Sharing that dynamically computes the minimal bandwidth of a cell according to its ratio of used bandwidth and available bandwidth. In the first step, the proposed solution is applied to the channel assignment scheme Reuse 3 and compared to a state of the art inter-cellular scheduling strategy in order to underline the benefits of the dynamic minimal bandwidth adaptation. In the second step, we have applied our methodology to the Fractional Frequency Reuse (FFR) scheme and compared it to the four frequency allocation schemes, Reuse 1, Reuse 3, FFR and Soft Frequency Reuse (SFR), as well as to a reference Dynamic FFR (D-FFR) solution that does not take into consideration the needs of the cells in terms of minimal bandwidth while redistributing the radio resources. Simulation results show that although the D-FFR scheme enhances the performances of the overloaded cell, it deteriorates the performance of the neighboring under-loaded ones. On the contrary, our solution called FFR D I B F S improves the provided Quality of Service (QoS) of both the congested cells and the whole cellular network.

      PubDate: 2017-09-15T12:10:16Z
      DOI: 10.1016/j.phycom.2017.09.002
  • Cooperative spectrum sharing in cognitive radio networks: An interference
           free approach
    • Authors: Md Fazlul Kader; Mohammad Irfan; Soo Young Shin; Seog Chae
      Abstract: Publication date: Available online 7 September 2017
      Source:Physical Communication
      Author(s): Md Fazlul Kader, Mohammad Irfan, Soo Young Shin, Seog Chae
      We present a novel interference free dual-hop cooperative spectrum sharing protocol in cognitive radio networks exploiting spatial modulation (SM) at both primary transmitter (PT) and secondary transmitter (ST). A ST equipped with multi-antenna acts as a half-duplex decode-and-forward relay for the primary system. During phase-1, SM is invoked at PT, while ST keeps silent. The information bit stream of PT is mapped into two different sets: the M -ary phase shift keying ( M -PSK)/ M -ary quadrature amplitude modulation ( M -QAM) bits and the antenna index. The ST then exploits iterative-maximum ratio combining ( i -MRC) technique to de-map the block of information bits, transmitted by PT. During phase-2, ST forwards the primary data by activating only one antenna based on its own secondary data exploiting the concept of SM. The PT’s data is then retrieved at the primary receiver (PR) and the secondary receiver (SR) recover its own desired data by detecting only the transmit antenna indices of ST using i -MRC. As a result, mutual interference between primary and secondary systems is avoided and interference cancellation techniques at the PR and SR are no longer needed. In the proposed protocol, the primary user does not need to lease its spectrum or time slots to the secondary user in exchange for cooperation. Moreover, power of ST does not need to be distributed for primary and secondary transmission simultaneously during phase-2. The simulation and analytical results are presented to show effectiveness of the proposed protocol compared to conventional spectrum leasing and superposition coding based overlay protocols.

      PubDate: 2017-09-09T10:30:51Z
      DOI: 10.1016/j.phycom.2017.09.001
  • Error probability model for IEEE 802.15.4 wireless communications in the
           presence of co-channel interference
    • Authors: Peter
      Abstract: Publication date: Available online 5 September 2017
      Source:Physical Communication
      Author(s): Uroš Pešović, Peter Planinšič
      The IEEE 802.15.4 standard is the most widely used for the realization of Wireless Sensor Networks (WSN) and Internet of Things (IoT) applications. The effects of various disturbances on IEEE 802.15.4 wireless transmissions in the 2.4 GHz band have been studied previously for background noise, multipath fading, wideband and narrowband interference caused by WiFi and Bluetooth networks. The influence of co-channel interference, which originates from collisions between IEEE 802.15.4 devices which perform simultaneous radio transmission, has not been investigated previously. The IEEE 802.15.4 standard uses the Carrier Sense Medium Access with Collision Avoidance (CSMA/CA) channel access mechanism to prevent collisions between devices, but this mechanism doesn’t provide protection from a hidden node problem, which is the primary source of co-channel interference. Hidden node collision in the CSMA/CA channel access mechanism occurs because of the time-spatial relation between nodes located inside the radio range of the recipient device. In our paper, we determined the spatial probability for k -tuple of mutually hidden nodes using the Monte Carlo simulation method. Furthermore, we analyzed the influence of co-channel interference on the error probability of IEEE 802.15.4 communication, and derived accurate analytical models by considering the non-ideal features of the used spreading sequences. The accuracy of the derived mathematical models was tested by numerical Monte Carlo simulation of the IEEE 802.15.4 communication and in a real-world experiment using IEEE 802.15.4 compliant wireless transceivers for creating co-channel interference. The presented simulation and real world experiment results show consistency with the proposed analytical error probability models.

      PubDate: 2017-09-09T10:30:51Z
  • MRC SC-FDMA scheme performance evaluation based on measurements at
           30 GHz for 5G communications
    • Authors: Abdellatif Khelil; Larbi Talbi; Djamel Slimani; Jules LeBel
      Abstract: Publication date: Available online 1 September 2017
      Source:Physical Communication
      Author(s): Abdellatif Khelil, Larbi Talbi, Djamel Slimani, Jules LeBel
      Millimeter-wave band between 30-300 GHz frequencies combined with SC-FDMA are promoted to be a potential technology enabler for 5G mobile network in the uplink. So, in this paper an MRC SC-FDMA scheme based on measurement at 30 GHz is proposed for 5G system. Measurements were taken between three buildings under a non-line-of-sight (NLOS) scenario for a path length of 183m. The measured impulse response was used to evaluate the PAPR, the BER and the channel capacity. A MRC combiner is used to maximize the instantaneous SNR at the output of SIMO schemes. Simulation results show a PAPR gain of 3.3 dB for the MRC-ISC-FDMA over MRC OFDMA system. The MRC SIMO (1x3) provides a BER gain of 5.2 and 4.4 dB over the traditional ISC-FDMA and LSC-FDMA respectively. Moreover, channel capacity simulations corroborate the significant increases of capacity with the increasing of the number of antennas at the receiver (achievable date rate of 6.48 Gbps at SNR = 15 dB in SIMO 1 × 3 configuration). These results validate the viability of outdoor mm-waves link (30 GHz) under NLOS conditions for radio access transmission, where high transmission efficiency and data rates could be achieved. Hence, these results motivate the use of MRC SC-FDMA waveform for 5G mobile communications in the uplink.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.018
  • Cooperative spectrum sensing based on a modified shuffled frog leaping
           algorithm in 5G network
    • Authors: Xunqian Tong; Yanju Ji; Jun Lin; Jinbao Zhu; Feng Sun; Yi Zhong; Yang Yang; Xi Zhu
      Abstract: Publication date: Available online 30 August 2017
      Source:Physical Communication
      Author(s): Xunqian Tong, Yanju Ji, Jun Lin, Jinbao Zhu, Feng Sun, Yi Zhong, Yang Yang, Xi Zhu
      The explosion of different types of wireless communications is leading to an impending spectrum famine. As a result, spectrum sensing has gained increasing interest from governments, industry and regulators. In this paper, a novel approach for cooperative spectrum sensing is proposed based on a modified shuffled frog leaping algorithm (SFLA). This approach is to fuse the perceived results of multiple nodes, and to improve the detection reliability. Simulations are used to compare the performance of the modified SFLA to the conventional one. The performance of the proposed cooperative spectrum sensing method based on the modified SFLA and that of the cooperative spectrum sensing method using modified deflection coefficient (MDC) are also compared. Results show that the proposed SFLA outperforms the traditional SFLA, and the proposed cooperative spectrum sensing method based on the modified SFLA gives higher miss detection probability than the MDC-based method, which validates the effectiveness of the modified SFLA-based cooperative sensing method.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.014
  • Performance analysis of distributed MIMO with ZF receivers over gamma
           shadowed correlated Rician fading channels
    • Authors: Xingwang Li; Ya Li; Lihua Li; Jin Jin; Charles C. Cavalcante
      Abstract: Publication date: Available online 26 August 2017
      Source:Physical Communication
      Author(s): Xingwang Li, Ya Li, Lihua Li, Jin Jin, Charles C. Cavalcante
      In this paper, we study the performance of distributed multiple-input multiple-output (D-MIMO) systems over correlated Rician/Gamma (RG) fading channels employing zero-forcing (ZF) receivers. Contrary to the existing works, we consider the arbitrary-rank deterministic Rician multipath fading and Gamma shadowing fading. Based on this fading model, the novel analytical expressions for the achievable sum rate (ASR), symbol error ratio (SER), and outage probability (OP) are derived, followed by the asymptotic performance at both high- and low- signal-to-noise ratio (SNR) regimes. However, the final results involve special functions like Bessel, Meijer-G functions, which do not provide engineering insights for practical systems. To solve this problem, the approximate analyses for the ASR, SER, OP are executed using moment matching method. Finally, we perform the large-system analysis of the ASR and provide asymptotic expressions when the number of antennas at the base station (BS) grows large, and when the number of antennas at both ends grows large with a fixed and finite ratio. It is demonstrated that the proposed approximate expressions accurately match with the analytical expressions, especially for massive MIMO systems.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.013
  • Low complexity optimization for user centric cellular networks via large
           dimensional analysis
    • Authors: Longwei Wang; Qilian Liang
      Abstract: Publication date: Available online 26 August 2017
      Source:Physical Communication
      Author(s): Longwei Wang, Qilian Liang
      Users near cell edges suffer from severe interference in traditional cellular networks. In this paper, we consider the scenario that multiple nearby base stations (BSs) cooperatively serve a group of users which is referred to as the cell free networks. A low complexity optimization method based on the large dimensional analysis is proposed. The advantage of the cell free networks is that the interference caused in the cell edge users can be converted into intended signal. It is not easy to obtain the optimal solution to the network due to coupled relations among the users’ rates. To obtain a suboptimal solution, a precoder that balances signal and interference is adopted to maximize the network capacity. In traditional optimization, it requires instantaneous channel state information. We try to optimize the network sum rate based on the large dimensional analysis. In this way, the optimization can be transformed into another problem that merely depend on the large scale channel statistics. Large dimensional analysis is leveraged to derive the asymptotic signal to interference plus noise ratio that only depends on large scale channel statistics. Based on this result, the power allocation problem does not need to adapt as frequently as the instantaneous channel state information. By this means, signal exchange overhead can be greatly reduced. Numerical results are provided to validate the efficacy of the proposed optimization method.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.001
  • Joint optimal fair cooperative spectrum sensing and transmission in
           cognitive radio
    • Authors: Xin Liu; Min Jia
      Abstract: Publication date: Available online 26 August 2017
      Source:Physical Communication
      Author(s): Xin Liu, Min Jia
      Since the sensing power consumption of cooperative spectrum sensing (CSS) will decrease the throughput of secondary users (SU) in cognitive radio (CR), a joint optimal model of fair CSS and transmission is proposed in this paper, which can compensate the sensing overhead of cooperative SUs. The model uses the periodic listen-before-transmission method, where each SU is assigned a portion of channel bandwidth, when the primary user (PU) is estimated to be free by the coordinator. Then, a joint optimization problem of local sensing time, number of cooperative SUs, transmission bandwidth and power is formulated, which can compensate the sensing overhead of cooperative SUs appropriately through choosing suitable compensating parameter. The proposed optimization problem can be solved by the Polyblock algorithm. Simulation results show that compared with the traditional model, the total system throughput of the fairness cooperation model decreases slightly, but the total throughput of the cooperative SUs improves obviously.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.015
  • A spectrum auction algorithm based on joint power control and beamforming
           in small cell networks
    • Authors: Feng Zhao; Yuyi Zhang; Hongbin Chen
      Abstract: Publication date: Available online 24 August 2017
      Source:Physical Communication
      Author(s): Feng Zhao, Yuyi Zhang, Hongbin Chen
      Spectrum auction is considered as a suitable approach to efficiently allocate spectrum among unlicensed users. However, in previous studies of spectrum auction, competition can hardly be reflected in the traditional spectrum allocation and the spectrum efficiency is still not high after the allocation. In this paper, we enhance the factor of competition in the auctions, in which bidders need to pay for the competition and the interference to macro cell users (MUs). We consider a communication system with one macro cell and several small cells, thus a licensed radio spectrum is shared by both MUs and small cell users (SUs). A truthful auction algorithm is proposed for spectrum allocation and the spectrum is divided into multiple channels in different time slots, so that SUs can make their choice for bidding under the guidance of history. In order to raise the communication quality, we propose a power control and beamforming algorithm in the heterogeneous network to enhance the system performance. Simulation results are presented to verify the effectiveness of the proposed algorithm in the small cell network.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.008
  • Performance analysis of non-coherent MIMO MRC scheme with training using
           finite-SNR diversity and multiplexing tradeoff
    • Authors: Nandita Lavanis; Devendra Jalihal
      Abstract: Publication date: Available online 23 August 2017
      Source:Physical Communication
      Author(s): Nandita Lavanis, Devendra Jalihal
      The inherent tradeoff between the twin benefits offered by multiple antenna systems, namely, the diversity gain and the multiplexing gain is captured as the diversity multiplexing tradeoff (DMT). The DMT at asymptotically high signal-to-noise ratio (SNR) is optimistic, whereas at finite SNR, it is practical. In this paper, point-to-point multiple input multiple output (MIMO) systems are considered under the assumption of coherent and non-coherent communication implying, respectively, whether perfect channel state information is available at the receiver (CSIR) or not. The literature mainly addresses non-coherent communication with training at asymptotically high SNR, whereas the finite-SNR analysis is more relevant in practice. We address the performance analysis of a MIMO maximal ratio combining scheme by deriving closed-form expressions of the DMT at finite SNR under non-coherent communication with training. At a fixed multiplexing gain and finite SNR, a reduction in the diversity gain is observed when coherent communication is replaced by non-coherent communication with training. We also show that for a high multiplexing gain, the reduction in diversity gain is much more pronounced as compared to that at a low multiplexing gain. A training-based channel estimation scheme discussed in the literature is used in two modes of power allocation, namely, the capacity optimal power allocation and equal power allocation (EPA). In both modes, at a fixed average SNR and with equal duration of training, we observe that the power allocation mode does not make a significant impact on the finite-SNR DMT of the MIMO scheme. We also observe that in the EPA mode, the diversity gain reduces with increase in training duration.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.012
  • Learning to short-time Fourier transform in spectrum sensing
    • Authors: Longmei Zhou; Zhuo Sun; Wenbo Wang
      Abstract: Publication date: Available online 19 August 2017
      Source:Physical Communication
      Author(s): Longmei Zhou, Zhuo Sun, Wenbo Wang
      The future wireless communication will come up with a strict requirement on high spectral efficiency, developing novel algorithms for spectrum sensing with deep sensing capability will be more challenging. However, traditional expert feature-based spectrum sensing algorithms are lack of sufficient capability of self-learning and adaptability to unknown environments and complex cognitive tasks. To address this problem, we propose to build up a deep learning network to learn short time-frequency transformation (STFT), a basic entity of traditional spectrum sensing algorithms. Spectrum sensing based on the learning to STFT network is supposed to automatically extract features for communication signals and makes decisions for complex cognitive tasks meanwhile. The feasibility and performances of the designed learning network are verified by classifying signal modulation types in deep spectrum sensing applications.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.007
  • Partially overlapping filtered multitone with reconfigurable antennas in
           uncoordinated networks
    • Authors: Mustafa Harun Yılmaz; Selçuk Köse; Nowrin H. Chamok; Mohammod Ali; Hüseyin Arslan
      Abstract: Publication date: Available online 19 August 2017
      Source:Physical Communication
      Author(s): Mustafa Harun Yılmaz, Selçuk Köse, Nowrin H. Chamok, Mohammod Ali, Hüseyin Arslan
      Partially overlapping tones (POT) have recently been offered as a promising solution with the aim of decreasing the interference induced on the users for uncoordinated networks. Since each user causes interference on other users while utilizing the same resources, a reduction on this destructive interference can be achieved with POT concept. In this study, a game theoretical partially overlapping filtered multitone scheme is proposed. Partially overlapping is performed in both frequency and space domains. While intentional carrier frequency shift is introduced in frequency, reconfigurable antennas are utilized to achieve partially overlapping in space domain. Within a game theoretical framework, when users search for the frequency shift ratio, they also select the antenna state to increase the system utility. When the users act simultaneously, joint behavior makes it increasingly difficult to reach the Nash equilibrium (NE). To address this problem, a sequential game algorithm is utilized. As a result, the NE is proved theoretically with potential games and simulations. With this joint partially overlapping game in frequency and space domains, it is demonstrated that the capacity gain at system level is improved significantly.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.005
  • Channel estimation for massive MIMO with 2-D nested array deployment
    • Authors: Fangqi Zhu; Na Wu; Qilian Liang
      Abstract: Publication date: Available online 17 August 2017
      Source:Physical Communication
      Author(s): Fangqi Zhu, Na Wu, Qilian Liang
      The problem of channel estimation in 5G is regarded as the one of the bottleneck problems due to its complexity related with large number of antenna elements at the BS side and more narrower beams when choosing high frequency such as millimeter wave. In this paper, we study the channel estimation problem for massive MIMO with a new antenna array at the base station (BS) side. The randomly deployed single antenna user equipments (UEs) within a single cell in the cellular network comprise of a random array. Based on the geometric channel model, using multiple snapshots of beamforming and combining vectors at the BS and UEs side respectively, the problem is formulated as a sparsity-aware problem and the coordinate descent algorithm is employed to retrieve the significant channel gain. Simulation results show the effective of the algorithm under two different scenarios with high SNR and low SNR respectively and for both cases, we can find the significant paths with properly chosen penalization parameter λ .

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.009
  • Pilot tones design using Grey Wolf Optimizer for OFDM–IDMA system
    • Authors: Necmi
      Abstract: Publication date: Available online 16 August 2017
      Source:Physical Communication
      Author(s): Şakir Şimşir, Necmi Taşpınar
      Since the channel estimation performance is affected directly by the positions of pilot tones, the optimization of pilot placement process known as having quite important role on minimizing the estimation errors has become a significant task for the multicarrier transmission technologies. Therefore, we propose Grey Wolf Optimizer (GWO) for pilot tones optimization to enhance the performance of Least Squares (LS) algorithm employed for channel estimation in Orthogonal Frequency Division Multiplexing – Interleave Division Multiple Access (OFDM–IDMA) system. Besides, the upper bound of Mean Square Error (MSE) which can be derived through Gershgorin disc theorem is used as an objective function of GWO to get rid of computing matrix inversion that is indispensable when computing MSE. In the simulations, our proposed GWO based pilot design method is compared to random, equispaced, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) based pilot placement strategies in terms of MSE and bit error rate (BER) criteria. The simulation results in which our proposed technique leaves behind the other considered strategies demonstrates that GWO based pilot design method is a promising pilot placement strategy for OFDM–IDMA system because of its high performance and low computational complexity.

      PubDate: 2017-09-03T07:28:22Z
  • PAPR analysis of superimposed training based SISO/MIMO-OFDM systems with
           orthogonal affine precoder
    • Authors: E. Sharma; Himanshu B. Mishra; K. Vasudevan; Rohit Budhiraja
      Abstract: Publication date: Available online 15 August 2017
      Source:Physical Communication
      Author(s): E. Sharma, Himanshu B. Mishra, K. Vasudevan, Rohit Budhiraja
      Superimposed training (ST) is used to estimate channel in orthogonal frequency division multiplexing (OFDM) systems which results in higher throughput than the time/frequency multiplexed training schemes. Orthogonal affine precoders (OAP) are used in ST-based SISO/MIMO-OFDM system to cancel the interference caused due to simultaneous data transmission. We analyze the peak to average power ratio (PAPR) of SISO/MIMO-OFDM systems which use OAP-based ST scheme. We show that the OAP-based ST scheme has higher PAPR than the conventional OFDM (without OAP-based ST) systems. We design an OAP using Zadoff–Chu (ZC) sequence, which has lower PAPR than the conventional OAPs. We further reduce the PAPR of the ST systems using selective mapping (SLM), but by increasing the system complexity. We show that the PAPR of the ST-based SISO/MIMO-OFDM systems with ZC-based OAP and SLM is identical to that of the conventional OFDM using SLM.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.004
  • Performance analysis of different Sum-of-Sinusoids simulation models for
           Rayleigh fading wireless channels
    • Authors: Mohamed Ali Skima; Hamadi Ghariani; Mongi Lahiani
      Abstract: Publication date: Available online 10 August 2017
      Source:Physical Communication
      Author(s): Mohamed Ali Skima, Hamadi Ghariani, Mongi Lahiani
      In this paper, extensive computations are conducted to assess the performance of five of the most accepted sum-of-sinusoids (SOS) simulation models for Rayleigh fading channels in terms of both accuracy and complexity. The statistical properties of first-, second- and higher-order are investigated using appropriate quantitative measures. This study is carried out for various numbers of sinusoids in order to find the better trade-off between complexity and accuracy. Moreover, for the correlation statistics, different numbers of simulation trials are used to better conclude about the ergodicity property of the different models. Numerical results demonstrate that, a recently introduced non-ergodic stochastic model exhibits a “likely-ergodic” behavior and its correlation functions vary little over the simulation trials. The variances of the time-averaged correlation functions are used to investigate the convergence behavior of the stochastic non-ergodic models. In this connection, analytical expressions of the variances of these functions are derived and compared with the simulated ones. In addition, the accuracy of the models is inspected through the mean and variance of the level crossing rate (LCR) and the average fade duration (AFD) relative errors.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.003
  • Non-cooperative game of effective channel capacity and security strength
           in vehicular networks
    • Authors: Zemin Sun; Yanheng Liu; Jian Wang; Weiwen Deng; Shaoqing Xu
      Abstract: Publication date: Available online 9 August 2017
      Source:Physical Communication
      Author(s): Zemin Sun, Yanheng Liu, Jian Wang, Weiwen Deng, Shaoqing Xu
      Vehicular ad-hoc networks pose stringent requirements on quality-of-service (QoS) and security strength in parallel because of their open channels and highly dynamic topology. Harmonizing these two conflicting goals is an urgent challenge, especially in VNs that are characterized by restrictive resources, e.g. bandwidth and link lifetime. This paper aims to balance the anticipated QoS and security strength in context to fully utilize limited network and computing resources to attain a satisfactory performance rating without compromising any security. To this end, we use non-cooperative game theory to formulate node utility, synthesizing the channel capacity and security strength from the perspective of adaptively controlling the transmit power and encryption block length in Nakagami multipath fading (NMF) channels. Moreover, we analyze the non-cooperative behavior of a “communication player” in controlling the transmit power and a “security player” in deciding the encryption block length, both of whom together strive to maximize the utility function at minimum cost. We then theoretically derive the pure strategy Nash equilibrium. Extensive numerical calculations are conducted to comprehensively investigate the reaction of the Nash equilibrium against the various combinations of the considered parameters. The results show that the proposed joint optimization method is capable of self-adapting to the vehicular context and improving the communication quality without compromising on security.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.08.002
  • MIMO relaying networks for cooperative spectrum sensing: False alarm and
           detection probabilities
    • Authors: Imen Souid; Haithem Ben Chikha; Iyad Dayoub; Rabah Attia
      Abstract: Publication date: Available online 7 August 2017
      Source:Physical Communication
      Author(s): Imen Souid, Haithem Ben Chikha, Iyad Dayoub, Rabah Attia
      In this paper, we investigate spectrum sensing in cooperative networks. Hence, in order to enhance cooperative sensing, we propose a novel model based on multiple-input multiple-output (MIMO) relaying broadcast channels with direct link and cognitive radio technology. Despite their efficiency in increasing transmission rates and networks capacities, MIMO relays have not yet been exploited for enhancing spectrum sensing. In this case, each relay is equipped with many antennas and the primary signal samples are collected by both MIMO relays and secondary user. Furthermore, we derive new expressions for the false alarm and detection probabilities as well as the detection threshold. Performance analysis are made for both soft and hard cooperative spectrum sensing schemes. Considering Gaussian and impulsive noise environments, simulations show that the proposed model allows a significant detection performance gain compared to non-cooperative cognitive MIMO models.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.07.006
  • Secure wireless multicasting with linear equalization
    • Authors: D.K. Sarker; M.Z.I. Sarkar; M.S. Anower
      Abstract: Publication date: Available online 4 August 2017
      Source:Physical Communication
      Author(s): D.K. Sarker, M.Z.I. Sarkar, M.S. Anower
      A confidential communication scenario is considered in which a base station (BS) transmits a common stream of information to a group of users in the presence of multiple eavesdroppers via multiple relays. Multiple relays are used to provide cooperative spatial multiplexing that significantly increases the spectral efficiency with the help of linear equalization at the users. In order to analyze the performance of proposed model showing the effect of fading and multiplexing gain, we derive the closed-form analytical expressions for the ergodic secrecy multicast capacity and the secure outage probability with and without equalization. Then, we study the effect of fading and shadowing, and the number of users, eavesdroppers and relays on the ergodic secrecy multicast capacity and the secure outage probability assuming channel state information at the receiver. The secure outage performances of the proposed model with zero-forcing (ZF) case are also compared without the case of ZF. In addition, we show the effect of the number of user and eavesdropper antennas and the distances from relays to users and eavesdroppers on the secure outage probability, and a comparison is shown between the composite and Rayleigh fading environments. Finally, the analytical expressions are verified via Monte Carlo simulation.

      PubDate: 2017-09-03T07:28:22Z
      DOI: 10.1016/j.phycom.2017.07.007
  • Spectrum sensing for OFDM signals using pilot induced cyclostationarity
           in the presence of cyclic frequency offset
    • Authors: Ribhu Chopra; Debashis Ghosh; D.K. Mehra
      Abstract: Publication date: Available online 1 August 2017
      Source:Physical Communication
      Author(s): Ribhu Chopra, Debashis Ghosh, D.K. Mehra
      In this paper, the problem of spectrum sensing of OFDM signals for cognitive radios is considered. It is proposed to detect the cyclostationary features introduced in an OFDM signal due to inter-pilot correlation. The performance of the proposed detector is derived and verified in case of AWGN channels. It is observed that the performance of cyclostationary detectors relies on the knowledge of the exact value of the cyclic frequency of the signal of interest. However, an offset in the cyclic frequency may arise due to several reasons. Therefore, for the proposed detector to perform reliably, there is a need to estimate the cyclic frequency offset. The Cramer-Rao bound for the cyclic frequency offset (CFO) estimator is derived, and based on it, two algorithms to estimate and compensate for the CFO are proposed. Simulation results are then used to study the performance of the proposed detection technique under Rayleigh fading both in the presence and the absence of CFO. The performance of the proposed system model is also studied under fast fading, and an alternative test statistic is proposed.

      PubDate: 2017-08-03T17:48:59Z
      DOI: 10.1016/j.phycom.2017.07.008
  • Carrier to interference ratio, rate and coverage analysis in shotgun
           cellular systems over composite fading channels
    • Authors: Asma Bagheri; Ghosheh Abed Hodtani
      Abstract: Publication date: Available online 31 July 2017
      Source:Physical Communication
      Author(s): Asma Bagheri, Ghosheh Abed Hodtani
      Wireless communication performance in shotgun cellular system (SCS: wireless communication system with randomly placed base stations) is analysed. Aiming at this analysis, (i) the carrier to interference ratio (CIR), as an important measure in a cellular network, is considered in the downlink (path-loss, shadowing and multi-path) fading channel. Since direct calculating of the distribution of CIR is complicated, a related mathematical equation is determined through which the probability density function (PDF) of CIR can be calculated. And then, as a special case, the tail probability of CIR is obtained. (ii) A normal approximation for inverse of CIR is proposed which is applicable for calculating a tractable PDF for the downlink CIR. The analytically calculated and the approximate PDFs of CIR are compared with numerical PDFs. (iii) The distribution of the downlink rate and a lower bound for the average rate; the analytical expression for coverage of a user in an SCS based on its received CIR, and an average value for coverage are calculated. (iv) Simulation results show that the closed form and approximate PDFs over different models are close to numerical ones.

      PubDate: 2017-08-03T17:48:59Z
      DOI: 10.1016/j.phycom.2017.07.005
  • Spectrum efficient power allocation schemes for OFDM cognitive radio with
           statistical interference constraints
    • Authors: Manoranjan Rai Bharti; Debashis Ghosh
      Abstract: Publication date: Available online 26 July 2017
      Source:Physical Communication
      Author(s): Manoranjan Rai Bharti, Debashis Ghosh
      In this paper, we study the power allocation problem for an orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) system. In a departure from the conventional power allocation schemes available in the literature for OFDM-based CR, we propose power allocation schemes that are augmented with spectral shaping. Active interference cancellation (AIC) is an effective spectral shaping technique for OFDM-based systems. Therefore, in particular, we propose AIC-based optimal and suboptimal power allocation schemes that aim to maximize the downlink transmission capacity of an OFDM-based CR system operating opportunistically within the licensed primary users (PUs) radio spectrum in an overlay approach. Since the CR transmitter may not have the perfect knowledge about the instantaneous channel quality between itself and the active PUs, the interference constraints imposed by each of the PUs are met in a statistical sense. We also study an optimal power allocation scheme that is augmented with raised cosine (RC) windowing-based spectral shaping. For a given power budget at the CR transmitter and the prescribed statistical interference constraints by the PUs, we demonstrate that although the on-the-run computational complexity of the proposed AIC-based optimal power allocation scheme is relatively higher, it may yield better transmission rate for the CR user compared to the RC windowing-based power allocation scheme. Further, the AIC-based suboptimal scheme has the least on-the-run computational complexity, and still may deliver performance that is comparable to that of the RC windowing-based power allocation scheme. The presented simulation results also show that both the AIC-based as well as the RC windowing-based power allocation schemes lead to significantly higher transmission rates for the CR user compared to the conventional (without any spectral shaping) optimal power allocation scheme.

      PubDate: 2017-08-03T17:48:59Z
      DOI: 10.1016/j.phycom.2017.07.003
  • Power allocation for multi-user OFDM-DCSK system in frequency selective
           fading channel
    • Authors: Majid Mobini; Mohammad Reza Zahabi
      Abstract: Publication date: Available online 16 July 2017
      Source:Physical Communication
      Author(s): Majid Mobini, Mohammad Reza Zahabi
      In this paper, we introduce a grouping approach for power allocation in the multi-user OFDM-DCSK (MU-OFDM-DCSK) system under the frequency selective fading channels. The suggested procedure is convenient also for the other comb-type non-coherent schemes with similar structure. Furthermore, we derive analytical bit error rate (BER) expression for the grouped scheme and offer an optimal power distribution policy for both the single- and multi-user scenarios. This power assignment strategy is formulated by a min-max problem with the target of the worst group BER minimization incorporating total power and interference constraints. Simulation results confirm the advantages of the proposed power allocation scheme.

      PubDate: 2017-07-24T13:45:22Z
      DOI: 10.1016/j.phycom.2017.07.002
  • On signal space diversity: An adaptive interleaver for enhancing physical
           layer security in frequency selective fading channels
    • Authors: Marwan Yusuf; Hüseyin Arslan
      Abstract: Publication date: Available online 16 July 2017
      Source:Physical Communication
      Author(s): Marwan Yusuf, Hüseyin Arslan
      Signal space diversity is a powerful technique that increases reliability of detection over fading channels. In this paper, we explore the ability of this technique to provide secure communication. We enhance the security of OFDM systems in frequency selective fading channels by providing more diversity gain to the legitimate user compared to an eavesdropper. This is done by adapting the interleaving pattern to the channel of the legitimate user in rich multipath environments, where spatially separated channels are typically independent to each other. This ensures secrecy in a time division duplex system, where the eavesdropper has no information regarding the channel of the legitimate user. The scheme can also be used in the conventional frequency division duplex system, which is more challenging in terms of security aspects because of the channel state information leakage. A theoretical analysis is presented on the bit-error probability in Rayleigh fading environment. The numerical results support the conclusion that adapting the interleaving pattern to the CSI of the legitimate user provides a gain in the bit-error rate performance over the eavesdropper.

      PubDate: 2017-07-24T13:45:22Z
      DOI: 10.1016/j.phycom.2017.07.001
  • Transmit power and bits/channel use adaption in competitive cognitive
           radio networks
    • Authors: Lutfa Akter; Neelanjana Subin Ferdous; Zobaer Ahmed
      Abstract: Publication date: Available online 11 July 2017
      Source:Physical Communication
      Author(s): Lutfa Akter, Neelanjana Subin Ferdous, Zobaer Ahmed
      In this paper, we propose an optimization framework to determine the distribution of power and bits/channel use to secondary users in a competitive cognitive radio networks. The objectives of the optimization framework are to minimize total transmission power, maximize total bits/channel use and also to maintain quality of service. An upper bound on probability of bit error and lower bound on bits/channel use requirement of secondary users are considered as quality of service. The optimization problem is also constrained by total power budget across channels for a user. Simulating the framework in a centralized manner shows that more transmit power is allocated in a channel with higher noise power and bits/channel use is directly proportional to signal to interference plus noise power ratio. The proposed framework is more capable of supporting high bits/channel use requirement than existing resource allocation framework. We also develop the game theoretic user based distributed approach of the proposed framework. We see that user based distributed solution also follows centralized solution.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.06.008
  • Determination of the best carrier frequency based on the system and
           environmental parameters in underwater acoustic systems
    • Authors: Abdollah Doosti-Aref; Ataollah Ebrahimzadeh
      Abstract: Publication date: Available online 5 July 2017
      Source:Physical Communication
      Author(s): Abdollah Doosti-Aref, Ataollah Ebrahimzadeh
      One of the most challenging features of underwater acoustic (UWA) channel in comparison with its terrestrial radio frequency counterpart is highly frequency-dependent path loss. Thus, utilizing efficient carrier frequencies in UWA systems can considerably reduce the path loss. In this context, this paper presents an approximate formula for determining the best carrier frequency based on both the system and environmental parameters. To achieve this goal, this research first addresses a simple algorithm including general steps for tuning the parameters of Francois and Garrison (FG) formula in the frequency range of 10 to 100 kHz based on the appropriate experimental data which can be acquired from any interest region. Second, for a more accurate modeling of path loss, this paper considers the loss due to the reflections of sound from both the rough surface and bottom of the sea by employing the ray theory. Third, this study presents a general algorithm for modification of the power spectral density (PSD) of ambient noise based on Wenz formula in the frequency range of 10 to 100 kHz and the required experimental measurements which can be simply collected from any interest channel. Moreover, it is mathematically demonstrated that the ambient noise in the frequency range of 10 to 100 kHz, can be generally approximated with a strict sense stationary (SSS) colored normal stochastic process which is ergodic not only in mean and covariance but also in distribution. Finally, an approximate formula for the best carrier frequency is derived by maximizing the sound to noise intensity ratio (SNR). To verify the validity of simplifications and approximations utilized in this study and to assess the performance of our proposed algorithms and formulas, experimental results obtained in the Strait of Hormuz (SoH) are compared with the original, simplified, and modified models under different scenarios.

      PubDate: 2017-07-12T09:52:57Z
      DOI: 10.1016/j.phycom.2017.06.006
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