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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  [3118 journals]
  • Antenna array thinning for interference mitigation in multi-directional
           antenna subset modulation
    • Authors: Amr Akl; Ahmed Elnakib; Sherif Kishk
      Pages: 31 - 39
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Amr Akl, Ahmed Elnakib, Sherif Kishk
      Due to the increasing demand for wireless communications, millimeter-wave band has gained a great attention recently. Also, achieving secure wireless communications is of high importance. Antenna subset modulation is a low complexity single beam directional modulation technique suitable for millimeter-wave wireless communications, whereas multi-beam antenna subset modulation is a multi-directional, generalized form of antenna subset modulation. In this paper, interference mitigation for multi-beam antenna subset modulation via side lobe level reduction is introduced. A method for designing thinned arrays with minimum side lobe levels for antenna subset modulation is introduced and generalized for multi-beam antenna subset modulation. A new variable constraint is applied to the optimization problem to control the localization of optimum solution within the antenna array. Two solutions are introduced, convex optimization combined with local search and local search assisted genetic algorithm. Simulation results show the superiority of the proposed algorithms compared to simulated annealing algorithm and traditional genetic algorithm.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.11.005
      Issue No: Vol. 26 (2017)
  • A comprehensive survey: Small cell meets massive MIMO
    • Authors: Shweta Rajoria; Aditya Trivedi; W. Wilfred Godfrey
      Pages: 40 - 49
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Shweta Rajoria, Aditya Trivedi, W. Wilfred Godfrey
      The deluge of huge data demanding applications has imposed a challenge for next generation cellular system to support high data rate with reduced energy consumption besides ensuring good quality of service. Massive MIMO and small cells are the foremost technologies to address such challenges. Massive MIMO technique refers to deploying a very large number of antennas at the base station, and thus, improving energy efficiency and spectral efficiency of wireless networks. Small cell provides high data rate and good coverage with reduced transmit power by decreasing the distance between base station and user. This paper surveys state of the art of massive MIMO technique with small cell network. First, we discuss fundamental background for massive MIMO. Then, performance metrics and modeling tools for system analysis are studied. Next, details of enabling technologies to massive MIMO small cell network are stated in the paper. Finally, the paper highlights future challenges and research problems.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.11.004
      Issue No: Vol. 26 (2017)
  • Efficient scheduling and power allocation for multiuser decoding receivers
           in OFDMA networks with minimum rate requirements
    • Authors: Yakup K. Yazarel; A. Özgür Yılmaz
      Pages: 60 - 70
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Yakup K. Yazarel, A. Özgür Yılmaz
      In recent years, techniques for exploiting interference on the receiver side to improve the performance of future cellular networks have been of interest. Due to the dominance of data in network traffic, user rate demands are becoming crucial for resource allocation of cells in the network. We propose an efficient transmission scheme for the downlink of an OFDMA multicell multiuser system with multiuser decoding (successive interference cancellation (SIC), joint decoding (JD), single decoding (SD)) capable receivers. We define a marginal rate maximization problem taking into account minimum rate demands of users and develop a practical scheduling (subchannel assignment) and power allocation algorithm using Lagrangian dual decomposition and gradient (ellipsoid and projected subgradient) methods. In the subchannel assignment, we propose the ratio of direct-to-cross channel strengths and multiuser rate regions different than the studies in the literature. Through Lagrangian dual decomposition, we derive the optimal power allocation rule using multiuser decoding modes for a given subchannel assignment. We observe that the method proposed here has low computational complexity and can be easily integrated to next generation networks as well as achieving high performance in practical scenarios.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.11.006
      Issue No: Vol. 26 (2017)
  • Joint Pilot Placement and Symbol Design Scheme for Sparse Channel
           Estimation in OFDM systems
    • Authors: Anthony Ngozichukwuka Uwaechia; Nor Muzlifah Mahyuddin
      Pages: 71 - 80
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Anthony Ngozichukwuka Uwaechia, Nor Muzlifah Mahyuddin
      Most existing works on the deterministic pilot design for sparse Channel Estimation (CE) in Orthogonal Frequency Division Multiplexing (OFDM) system are based on the assumption that the pilot symbols are equally-powered. This assumption may not necessarily exhibit low coherence compressed CE. This, therefore, calls for the optimization of pilot symbols and their placement which in the literature is considered as a disjoint optimization problem. In this paper, the joint pilot placement and symbol design optimization problem for sparse CE in OFDM systems is considered based on minimizing the mutual coherence of the Fourier submatrix associated with the pilot subcarriers. In order to avoid the disjoint optimization of the pilot symbol values and their placements, a joint pilot placement and pilot symbol design scheme is proposed that optimizes over both the pilot symbol values and their placements as a single design optimization problem. Simulation results demonstrate that the proposed scheme is effective and offer a better CE performance — in terms of Mean Square Error (MSE) and Bit Error Rate (BER), when compared to former pilot placement schemes that assume the equally powered pilot symbols and other schemes that jointly design the pilot symbols and their placement. It was also observed that the proposed scheme can realize 18.75% improvement in bandwidth efficiency with the same CE performance compared with the least squares (LS) CE.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.11.008
      Issue No: Vol. 26 (2017)
  • Sensor selection for extending lifetime of multi-channel cooperative
           sensing in cognitive sensor networks
    • Authors: Asma Bagheri; Ataollah Ebrahimzadeh; Maryam Najimi
      Pages: 96 - 105
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Asma Bagheri, Ataollah Ebrahimzadeh, Maryam Najimi
      Wireless cognitive sensor networks (WCSNs) are composed of tiny, low-power and low-cost sensors. An important function of these networks is to sense the channels in order to find the spectrum holes. Sensors cannot sense more than one channel simultaneously because they do not have high-speed Analog-to-Digital-Converters (ADCs) which need high-power batteries. Therefore, it is a challenging issue to select cooperative sensors to sense different channels so that all the channels can be sensed simultaneously. On the other hand, lifetime extending in a WCSN is an important issue; it has attracted the most attention recently. In this paper, a tuneable receiver is used for sensors so that they can sense different channels in different sensing periods. To reduce energy consumption, node selection is proposed so that only sufficient nodes perform sensing the channels while the sensing quality constraints are met. A subset of nodes to sense every channel is selected in a way that the residual energy of sensors is balanced and the network lifetime is maximized. The problem can be solved based on the convex optimization framework. Closed form priorities of sensors to sense different channels are determined based on their residual energy, distance and detection probability. Then efficient dynamic sensor selection algorithms are proposed for multi-channel CSS. Simulation results show the advantages of the proposed algorithms in finding the efficient answer. In addition, in terms of network lifetime, success percentage, and energy consumption, the proposed algorithms are compared with the other sensor selection methods.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.11.003
      Issue No: Vol. 26 (2017)
  • Energy beamforming for full-duplex wireless-powered communication networks
    • Authors: Shuai Wang; Liqiang Zhao; Kai Liang; Xiaoli Chu; Bingli Jiao
      Pages: 134 - 140
      Abstract: Publication date: February 2018
      Source:Physical Communication, Volume 26
      Author(s): Shuai Wang, Liqiang Zhao, Kai Liang, Xiaoli Chu, Bingli Jiao
      In this paper, we consider a full-duplex (FD) wireless-powered communication network (WPCN), where one FD hybrid access point (HAP) equipped with multiple antennas simultaneously transmits energy to and receives information from multiple users. Firstly, we propose a space division wireless energy allocation scheme and calculate the harvested energy in downlink wireless energy transfer (WET) for each user. Secondly, we derive an approximate closed-form expression of user’s achievable ergodic rate in uplink wireless information transfer (WIT). Thirdly, the energy allocation for different users is optimized under the max–min user fairness constraint, and a closed-form solution is obtained. Numerical results show that the simulation and the approximation of achievable rates are well matched, and energy beamforming can effectively suppress self-interference (SI), and improve rates as well as fairness among users. Moreover, FD-WPCNs are shown to outperform half-duplex (HD) WPCNs in rates with same number of antennas.

      PubDate: 2017-12-26T16:47:07Z
      DOI: 10.1016/j.phycom.2017.12.007
      Issue No: Vol. 26 (2017)
  • 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)
  • Performance bounds of different channel access priority classes in future
           Licensed Assisted Access (LAA) LTE networks
    • Authors: Abdel-karim Ajami; Hassan Artail
      Pages: 110 - 127
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 1
      Author(s): Abdel-karim Ajami, Hassan Artail
      The growing demand on data to enhance the user experience has motivated research toward increasing the efficiency of spectrum utilization by extending cellular technology such as LTE toward the unlicensed bands. Several studies have been done regarding the fair coexistence of LTE with legacy technologies such as WiFi in the unlicensed bands. Most of these studies show that when LTE adopts appropriate technology such as LAA, it can be a good neighbor to WiFi. However, few studies have targeted the impact of coexistence of several LAA networks on the performance of each other in the unlicensed bands. Hence, within this scope, this is the first work that uses stochastic geometry to analyze the effect of channel access priorities of four traffic classes defined recently by 3GPP release 14, on the performance of the network and the degree of efficiency that can be achieved. In particular, we consider load based equipment (LBE) based MAC protocol where we use stochastic geometry to model and analyze the coexistence of four channel access priority classes of LTE-LAA networks with persistent downlink transmissions as defined by 3GPP. Mainly, we focus on a single unlicensed frequency band transmissions. The locations of LAA eNodeBs (eNBs) for the four classes are modeled as four independent homogeneous Poisson point processes. Furthermore, we derive analytical closed form expressions for a set of performance metrics which are the medium access probability (MAP), signal-to-interference-plus-noise ratio (SINR) coverage probability, and rate coverage probability. Our analysis demonstrates the impact of channel access priorities used by different classes on their network performance.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.09.003
      Issue No: Vol. 25 (2017)
  • Joint optimization of component carrier selection and resource allocation
           in 5G carrier aggregation system
    • Authors: Weidong Gao; Lin Ma; Gang Chuai
      Pages: 293 - 297
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2016.12.002
      Issue No: Vol. 25 (2017)
  • Transport capacity of cooperative cognitive radio ad hoc networks
    • Authors: Jing Gao; Yinghui Zhang; Yang Liu
      Pages: 298 - 303
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.01.001
      Issue No: Vol. 25 (2017)
  • Performance analysis of relay-assisted uplink massive MIMO systems with
           zero-forcing receiver
    • Authors: Liang Han; Weixia Zou
      Pages: 304 - 309
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.02.001
      Issue No: Vol. 25 (2017)
  • Characterization of distributed mode crosstalk in few-mode fiber links
           with low MIMO complexity
    • Authors: Jiawei Han; Caifeng Qu
      Pages: 310 - 314
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.02.002
      Issue No: Vol. 25 (2017)
  • Investigation of quadrature imbalance compensation algorithm for coherent
    • Authors: Yupeng Li; Ming Li; Jiawei Han; Tingting Han
      Pages: 319 - 322
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.02.004
      Issue No: Vol. 25 (2017)
  • Gerchberg–Saxton algorithm based phase correction in optical
           wireless communication
    • Authors: Ming Li; Yupeng Li; Jiawei Han
      Pages: 323 - 327
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.02.008
      Issue No: Vol. 25 (2017)
  • Performance analysis of a novel 5G architecture via Content-Centric
    • Authors: Zhuo Li; Yankai Liu; Yutong Chen; Yaping Xu; Kaihua Liu
      Pages: 328 - 331
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      Author(s): Zhuo Li, Yankai Liu, Yutong Chen, Yaping Xu, Kaihua Liu
      Content-Centric Networking (CCN) is a recent paradigm conceived for future Internet architectures, where communications are driven by contents instead of host addresses. It binds the storage capacity into the network by using the in-network caching, which can reduce the transmission delay in the network. In this paper, a novel architecture of 5G via CCN, named as CCN-5G, is proposed. Meanwhile, the performance of CCN-5G are tested in the high-speed mobile environment. The simulation results show that the CCN-5G can achieve excellent performance and satisfy the future requirements of 5G.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.04.002
      Issue No: Vol. 25 (2017)
  • Auction-based spectrum allocation for CoMP systems utilizing hybrid
           division duplex
    • Authors: Feng Zhao; Yantao Miao; Hongbin Chen
      Pages: 332 - 340
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      Author(s): Feng Zhao, Yantao Miao, Hongbin Chen
      The coordinated multi-point (CoMP) transmission is a well-recognized promising technique for achieving high spectral efficiency. In this paper, we study the performance of the spectrum allocation and the system utility of the CoMP systems. First, we combine the hybrid division duplex (HDD) with a CoMP system to form a CoMP–HDD system, for the purpose of guaranteeing the quality demand of the channel state information (CSI) feedback. Second, in order to improve the system utility and the spectrum allocation efficiency of the CoMP–HDD system, we utilize the auction theory for the spectrum allocation. A system utility maximization problem is formulated as an NP-hard problem. Finally, we propose a multi-band multi-winner (MBMW) greedy algorithm to optimize the system utility and the spectrum allocation efficiency. Our simulation results demonstrate the effectiveness of the proposed algorithm.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.04.003
      Issue No: Vol. 25 (2017)
  • Leakage-based beamforming via game theory for reverse spectrum auction in
           cellular offloading systems
    • Authors: Feng Zhao; Xiaofei Xu; Hongbin Chen
      Pages: 341 - 347
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      Author(s): Feng Zhao, Xiaofei Xu, Hongbin Chen
      The explosion of mobile traffic and highly dynamic property often make it increasingly stressful for a cellular service provider to provide sufficient cellular spectrum resources to support the dynamic change of traffic demand in a day. In this paper, considering the dynamic characteristic of the cellular network traffic demand, we not only proposed an optimal, truthful reverse auction incentive framework, but also proposed a valuation function which is based on third-party access points’ capacity. We consider spectrum sharing in a third-party network where several secondary users (SUs) share spectrum with a primary user (PU). A leakage-based beamforming algorithm is proposed via game theory to maximize the sum utility of third-party access points subject to the signal-to-leakage-and-noise (SLNR) constraint of SUs and PU interference constraint. The sum throughput maximization problem is formulated as a non-cooperative game, where the SUs compete with each other over the resources. Nash equilibrium is considered as the solution of this game. Simulation results show that the proposed algorithm can achieve a high sum throughput and converge to a locally optimal beamforming vector.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.04.006
      Issue No: Vol. 25 (2017)
  • Multi-level quantization and blind equalization based direct transmission
           method of digital baseband signal
    • Authors: Maolin Ji; Jin Chen; Zeng Liu; Ying Tong; Fajie Duan; Tariq S. Durrani; Jiajia Jiang
      Pages: 348 - 354
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      Author(s): Maolin Ji, Jin Chen, Zeng Liu, Ying Tong, Fajie Duan, Tariq S. Durrani, Jiajia Jiang
      The direct transmission of digital baseband signals has practical significance in the field of Ethernet terminal connection, high-speed digital communication, data transmission of various types of information peripherals. The signal amplitude gradually decays while the transmission distance increases. Also the attenuation is proportional to the signal frequency, resulting in signal distortion and receiving error. It is a common method for digital baseband signal transmission to use pre-emphasis chip and equalizer chip to improve the transmission quality with a wide range of mature applications. This paper describes a new type of digital signal transmission method, as the receiver using analog-to-digital converter, instead of equalizer chip, to achieve the multi-level quantization of receiving time-domain data waveform. The waveform of the transmitted digital high and low level signal is sampled into multi-bit values. Then, the paper realizes adaptive frequency domain equalization based on soft threshold and makes use of multi-level quantization soft information for error correction. Error correcting code is mainly used to correct the error caused by the channel bandwidth limit, external noise or interference in the process of data transmission, so as to improve the stability and reliability of the transmission. The paper uses the two-stage error correcting codec system based on both Turbo and BCH coding, to achieve the high performance of Turbo code, and good characters of respond time and complexity. The transmitter outputs 12.5 MHz pseudo-random sequence through a 199.93 meter unshielded balanced twisted pair transmission medium. And the receiver circuit using a 62.5MSPS analog-to-digital converter over-samples the waveform to 8-level quantity. The output error of a 65536 bit pseudo-random sequence is less than 8 bits, and the error correction can be further improved by 8b-10b codec. Compared with the traditional pre-emphasis and balanced interface ICs connection, the method described in this article has the advantages of longer transmission distance, better flexibility and wider scope of use.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.04.008
      Issue No: Vol. 25 (2017)
  • A simplified massive MIMO implemented with pre or post-processing
    • Authors: Mário Marques da Silva; Rui Dinis
      Pages: 355 - 362
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      Author(s): Mário Marques da Silva, Rui Dinis
      This paper considers the use of massive multiple input, multiple output (MIMO) combined with single-carrier with frequency-domain equalization (SC-FDE) modulations, associated to millimeter wave (mm-Wave) communications using precoding. For the sake of comparison, this paper performs a comparison of pre and post-processing methodology, using the same algorithms. In this paper, we consider three different types of algorithms: Zero Forcing Transmitter (ZFT), Maximum Ratio Transmitter (MRT), and Equal Gain Transmitter (EGT), both of the latter two with iterative detection schemes. The advantage of both MRT and EGT relies on avoiding the computation of pseudo-inverse of matrices. The performance of MRT and EGT are very close to the matched filter bound just after a few iterations of a new proposed interference cancellation, even when the number of receiving antennas is not very high.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.06.002
      Issue No: Vol. 25 (2017)
  • Analysis and optimization of energy harvesting AF relaying with channel
    • Authors: Lumin Li; Yulin Zhou; Ning Cao; Jie Li
      Abstract: Publication date: Available online 24 December 2017
      Source:Physical Communication
      Author(s): Lumin Li, Yulin Zhou, Ning Cao, Jie Li
      In energy harvesting relaying, channel estimation needs to be performed to acquire channel state information at the relay and at the destination. Thus, the data packet from the source to the relay contains three parts: pilot for channel estimation, data symbols and pilots for harvesting. The data packet from the relay to the destination contains two parts: data symbols and pilots for estimation. In this paper, for a fixed packet size, the outage and bit error rate performances are analysed and then optimized with respect to power allocation between different parts in the data packet. The cumulative distribution function of the end-to-end signal-to-noise ratio is derived in closed-form, based on which outage and error rate can be calculated. Numerical results show the existence of the optimal values of the numbers of pilots for channel estimation and for energy harvesting, when the total size is fixed.

      PubDate: 2017-12-26T16:47:07Z
      DOI: 10.1016/j.phycom.2017.12.011
  • FOMP algorithm for Direction of Arrival estimation
    • Authors: Maryam Dehghani; Keyvan Aghababaiyan
      Abstract: Publication date: Available online 24 December 2017
      Source:Physical Communication
      Author(s): Maryam Dehghani, Keyvan Aghababaiyan
      Adaptive antennas and antenna array processing are much significant issues for improving the performance of wireless communication systems. One of the most important applications of adaptive antenna systems is the Direction of Arrival (DOA) estimation. Recently, compressive sensing algorithms, including convex relaxation methods and greedy algorithms, have been recognized as a type of novel DOA estimation methods. The Orthogonal Matching Pursuit (OMP) is an example of compressive sensing methods. Using the OMP method for DOA estimation has many advantages in comparison to other algorithms. In spite of these advantages, the DOA estimation by OMP algorithm has a substantial challenge. The OMP algorithm cannot distinguish between two adjacent signal sources. In the DOA estimation by OMP algorithm, when there are two adjacent sources, the mutual coherent condition of the compressive sensing methods is violated. The situation gets worse when there are two sources from two adjacent DOAs. In this situation, the beam former has a single peak. In this paper, we propose the Focused Orthogonal Matching Pursuit (FOMP) algorithm for estimation of DOA. The FOMP algorithm is an improved version of the OMP algorithm. It can detect two signal sources exactly when they are very close and beam former has a single peak corresponding to a direction between right directions. Simulation results demonstrate the advantages of the proposed scheme. It can be observed the FOMP algorithm could detect very close signal sources with a negligible error.

      PubDate: 2017-12-26T16:47:07Z
      DOI: 10.1016/j.phycom.2017.12.012
  • Optimal number of frames transmitted in a sensing based opportunistic
           spectrum access
    • Authors: Viswanathan Arunachalam; Garima Mishra; S. Dharmaraja
      Abstract: Publication date: Available online 21 December 2017
      Source:Physical Communication
      Author(s): Viswanathan Arunachalam, Garima Mishra, S. Dharmaraja
      The opportunistic spectrum access (OSA) has emerged as promising approach to increase the efficiency in spectrum sharing. The important feature of the OSA is to enable the unlicensed users or secondary users (SUs) to search for unused spectrum vacated by idle licensed user or primary user (PU). In this paper, we consider the maximization of the number of frames sent by the SUs during the idle period (white space) of the PU, while avoiding the infringement into the privileges of the PU. We set up this problem in terms of an optimal stopping problem. Explicit expression for the optimal number of frames that can be sent by the SUs in a white space is derived. Performance analysis for channel utilization and channel idle time is presented. Finally, the analytical results for optimal number of frames sent by SU in white space are numerically illustrated.

      PubDate: 2017-12-26T16:47:07Z
      DOI: 10.1016/j.phycom.2017.12.009
  • GFDM/OQAM performance analysis under Nakagami fading channels
    • Authors: Shravan Kumar Bandari; Venkata Mani Vakamulla; Anastasios Drosopoulos
      Abstract: Publication date: Available online 20 December 2017
      Source:Physical Communication
      Author(s): Shravan Kumar Bandari, Venkata Mani Vakamulla, Anastasios Drosopoulos
      A lot of attention has been given recently to future multicarrier (MC) modulation techniques, for high speed robust wireless systems, in order to serve upcoming envisioned needs. Generalized Frequency Division Multiplexing (GFDM), a candidate for 5G, is a non-orthogonal modulation technique, proposed as an alternative to Orthogonal Frequency Division Multiplexing (OFDM) for future wireless communication systems. However, due to its non-orthogonal nature, GFDM introduces intersymbol and intercarrier interference (ISI/ICI). To mitigate these effects and to improve Symbol Error Rate (SER) system performance we explored the near orthogonality concept based on Offset Quadrature Amplitude Modulation (OQAM) and made the adaptation to the conventional GFDM system model. In this paper, we investigate SER performance under the Nakagami- m and Nakagami- q (Hoyt) fading channels. Analytical expressions for this SER performance are derived and the obtained results match those of the simulations that were carried out and confirms the effectiveness of the proposed GFDM/OQAM model to that of conventional GFDM.

      PubDate: 2017-12-26T16:47:07Z
      DOI: 10.1016/j.phycom.2017.12.008
  • A low-interference decision-gathering scheme for critical event detection
           in clustered wireless sensor network
    • Authors: Saud Althunibat; Ala Khalifeh Raed Mesleh
      Abstract: Publication date: Available online 20 December 2017
      Source:Physical Communication
      Author(s): Saud Althunibat, Ala Khalifeh, Raed Mesleh
      This paper presents a new decision-gathering scheme that aims at detecting a critical event in an Area of Interests (AoI), where a wireless sensor network is deployed in a group of clusters. The proposed scheme assigns a single time slot for each cluster, where all cluster members simultaneously report their binary decisions to the cluster head on that time slot. As the cluster head is interested in the sum of the binary decisions (not the exact binary decisions), the performance loss due to the concurrent transmission is insignificant compared to the co-channel interference induced from other clusters based on conventional schemes. The main advantage of the proposed scheme is that it avoids the co-channel interference between different clusters and assures minimal delay in detecting the critical event, which is very crucial in many security related applications and scenarios. Both simulation and mathematical analysis of the overall decision-error probability of the proposed scheme are carried out, which demonstrate the effectiveness of the proposed scheme.

      PubDate: 2017-12-26T16:47:07Z
  • Device-centric resource allocation scheme for 5G networks
    • Authors: Pavan Kumar Mishra; Sudhakar Pandey; Siba K. Udgata; Sanjay Kumar Biswash
      Abstract: Publication date: Available online 16 December 2017
      Source:Physical Communication
      Author(s): Pavan Kumar Mishra, Sudhakar Pandey, Siba K. Udgata, Sanjay Kumar Biswash
      Device-centric architecture is an important aspect for fifth generation (5G) networks. The current cellular systems are base station-centric where the base-station (BS) is responsible for resource allocation. The BS allocates resources to users based on their channel state information (CSI) and feedback. This resource allocation process increases load at the BS side resulting in more time consumption. This decreases the overall network throughput and increases delay in resource allocation. Therefore, in this article, a device-centric resource allocation scheme is proposed for D2D users. In this scheme, interested D2D pairs can allocate the resource to themselves using the following three steps. In first step, devices maintain their resource occupancy matrix by exchanging the neighbouring information. In second step, a resource block is selected based on resource allocation scenarios. In third steps, resource block is allocated based on the priority on the BS side. The proposed scheme is less dependent on the BS side, hence it reduces the load on BS side and it also reduces time consumption in resource allocation process. Additionally, the proposed scheme improves the overall network throughput. A comparison of the proposed scheme with the base-centric scheme shows that proposed scheme is up to 35% more effective in each experimental case.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.12.003
  • An efficient guided local search approach for multiuser detection in UWB
    • Authors: Anis Naanaa; Safya Belghith
      Abstract: Publication date: Available online 16 December 2017
      Source:Physical Communication
      Author(s): Anis Naanaa, Safya Belghith
      In this paper, we tackled the performance of a multiuser detection (MUD) in ultra wideband (UWB) systems over extreme multipath channel model (CM4) based on TH-PPM and DS-PAM in a rake receiver. For better performance at receiver side, a novel guided local search (GLS) algorithm is proposed for UWB systems. Simulation results show a significant bit error rate (BER) performance gain can be achieved based on the proposed GLS-MUD method, with conventional detector (CD). In addition, the technique is very promising when the number of interfering users increases.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.12.006
  • Beam-domain full-duplex transmission in massive MIMO system
    • Authors: Kui Xu; Zhexian Shen; Yurong Wang; Xiaochen Xia
      Abstract: Publication date: Available online 15 December 2017
      Source:Physical Communication
      Author(s): Kui Xu, Zhexian Shen, Yurong Wang, Xiaochen Xia
      In this paper, we consider beam-domain full-duplex (FD) transmission in massive multiple-input multiple-output (MIMO) system. By exploiting the channel spatial sparsity, massive MIMO channel is compressed in the beam-domain under certain selected basis spaces and as a result the channel dimension required to be estimated can be greatly reduced. According to the distribution of effective beams of uplink/downlink channel and self-interference (SI) channel, all the users are scheduled into several uplink and downlink groups. With the estimated effective beam-domain channel, we design the uplink and downlink beamforming matrixes at the base station to suppress the SI, inter-user interference and inter-group interference. The achievable sum-rate of the proposed beam-domain FD massive MIMO transmission scheme is analyzed and the joint user and BS power allocation scheme is proposed to optimize the system achievable sum-rate. Simulation results show that the proposed beam-domain FD transmission scheme outperforms existing time division duplex (TDD) and frequency division duplex (FDD) massive MIMO and FD massive MIMO transmissions schemes on the spectral efficiency performance.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.12.004
  • Low-complexity MMSE detector based on refinement Jacobi method for massive
           MIMO uplink
    • Authors: Juan Minango; Andrea Carolina Flores
      Abstract: Publication date: Available online 15 December 2017
      Source:Physical Communication
      Author(s): Juan Minango, Andrea Carolina Flores
      Minimum mean square error (MMSE) linear detector can achieve the near-optimal bit error rate (BER) performance for uplink multi-user massive multiple input multiple output (MIMO) systems, but it involves matrix inversion with high complexity, especially when the number of users is high. In order to reduce the complexity, Jacobi iterative method has been applied for low-complexity MMSE detector without employing the computationally intensive matrix inversion. However, its convergence rate is low. In this paper, we propose a novel low-complexity MMSE detector based on the refinement of Jacobi iterative method. This refinement is given by the use of band matrix in order to accelerate the convergence rate, as well as guaranteeing the near-optimal BER performance. Analytical and simulation results show the efficiency of the proposed detector in comparison to the recently Jacobi-based detector.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.12.005
  • Impact of partial phase decorrelation on the performance of pilot-assisted
           millimeter-wave RoF-OFDM systems
    • Authors: David Zabala-Blanco; Gabriel Campuzano; Ivan Aldaya; Gerardo Castañón; César Vargas-Rosales
      Abstract: Publication date: Available online 11 December 2017
      Source:Physical Communication
      Author(s): David Zabala-Blanco, Gabriel Campuzano, Ivan Aldaya, Gerardo Castañón, César Vargas-Rosales
      It is well known that in radio over fiber (RoF) systems, the transmission performance of orthogonal frequency-division multiplexing (OFDM) is highly sensitive to phase noise. In these systems, the radio frequency (RF) signal is generated by beating a reference and a modulated signal at the base station and, therefore, the phase noise of the RF signal depends on the phase noise of both reference and modulated signals as well as on the correlation between them. In many RoF systems, the reference and modulated signals come from the same optical source and, consequently, they are affected by the same phase noise, i.e., perfect correlation. Unfortunately, chromatic dispersion of fiber progressively decorrelates the phase noise affecting both signals. This impairment is especial detrimental in RoF systems operating at millimeter waves, limiting the maximum achievable range. On the other hand, pilot-aided equalization has proven its potential to combat the impact of phase noise in OFDM signals. However, the complex interrelation between phase noise induced by partial decorrelation and pilot-aided equalization is still uncertain. In this paper, we present extensive simulation and theoretical results to assess the optical signal to noise penalty and range limitation caused by partial field decorrelation. We discovered three performance regimes in terms of the correlation degree. This finding was explained by both the profile of the power spectral density and the subcarrier phase noise. Whereas the former is a qualitative result, the latter allows to quantify the phase noise for an OFDM signal with partial decorrelation and phase noise mitigation. Our results revealed that the appearance of a third operating regime is due to pilot-assisted equalization. Finally, we found the range of RoF-OFDM systems for perfectly correlated fields at the transmitter.

      PubDate: 2017-12-17T19:33:27Z
      DOI: 10.1016/j.phycom.2017.12.002
  • Relay selection and power allocation for energy-efficient cooperative
           cognitive radio networks
    • Authors: M. Soleimanpour-moghadam; S. Talebi
      Abstract: Publication date: Available online 6 December 2017
      Source:Physical Communication
      Author(s): M. Soleimanpour-moghadam, S. Talebi
      In this paper, we apply the innovative multi-objective optimization methods to the challenge posed by rate maximization, total transmission power minimization and relay selection in cooperative cognitive radio networks. The proposed methods which are based on amplify and forward relaying strategy optimize the three conflicting objectives and, at same time, they maximize the rate quality, minimize the total transmission power allocated to the network relays and make the best relay node selection. The multi-objective optimization studied is a non-convex non-linear combinatorial algorithm which is converted to its convex smooth equivalent through two efficient approximation methods. We apply the multi-objective lexicographic method to overcome the challenge posed by these conflicting objectives simultaneously. The proposed relay node selection method is based on zero-norm principle which provides an effective technique to obtain a minimum node selection. Simulation results confirm that the proposed approaches offer superior performance over known schemes in terms of throughput gain and number of active relays.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.11.007
  • Block-sparse hybrid precoding and limited feedback for millimeter wave
           massive MIMO systems
    • Authors: Xuefeng Liu; Weixia Zou
      Abstract: Publication date: Available online 6 December 2017
      Source:Physical Communication
      Author(s): Xuefeng Liu, Weixia Zou
      Millimeter wave (mmWave) communication using massive multiple input multiple output (MIMO) techniques has been regarded as a key enabling technology for 5G wireless system, as it can offer gigabit-per-second data rates. Due to the high cost and power consumption of mixed-signal devices in mmWave systems, the hybrid analog and digital precoding transceiver architecture has recently received considerable attention. In this paper, we fully deploy spatial structure of mmWave channel to find hybrid precoders with near-optimal performance and reduce the number of feedback bits. MmWave MIMO channel exhibits the block sparsity structure because of the limited number of scattering clusters with low angular spreads. Consequently, we formulate hybrid precoders design as a block-sparse reconstruction problem and a lower complexity algorithm for finding precoders is proposed based on the greedy sequence clustering. To assure the performance of this algorithm, a estimation method for the number of the blocks and radio frequence (RF) chains is proposed. Under this framework, for the analog precoder the number of the phases needed to be quantized is only two times minus one of that of all blocks, which remains unchanged even the number of RF chains increases. The simulation results demonstrate that the proposed algorithm can achieve the near-optimal performance and save the feedback overhead by utilizing the block sparsity information.

      PubDate: 2017-12-11T15:03:45Z
      DOI: 10.1016/j.phycom.2017.12.001
  • Generalized space modulation techniques: Hardware design and
    • Authors: Raed Mesleh; Omar Hiari Abdelhamid Younis
      Abstract: Publication date: Available online 5 December 2017
      Source:Physical Communication
      Author(s): Raed Mesleh, Omar Hiari, Abdelhamid Younis
      Generalized space modulation techniques (GSMTs), such as generalized space shift keying (GSSK) and generalized spatial modulation (GSM), activate a block of transmit antennas at one time instant to transmit the same data symbol. The aim is to allow the use of arbitrary number of transmit antennas not necessarily power of two. In this paper, novel generalized quadrature space shift keying (GQSSK) and generalized quadrature spatial modulation (GQSM) are presented and analyzed. It has been debated in the literature that these schemes require a number of RF–chains equal to the number of active antennas. In this paper, the design of the transmitters for all GSMTs with optimum number of required RF–chains are discussed and hardware limitations are briefly addressed. A general framework for analyzing the average bit error probability of all these systems is presented and shown to accurately predict the error performance over Rayleigh fading channels. Besides, receiver computational complexity, transmitter power consumption and a rough estimate on the hardware implementation costs for all these schemes are discussed and compared. It is shown that the transmitter implementation of all these schemes requires at most single RF–chain and in some cases no RF–chain is needed. In addition, it is revealed that GQSSK scheme outperforms all other systems and demonstrate the best error performance with low complexity, very low power consumption and modest implementation costs.

      PubDate: 2017-12-11T15:03:45Z
  • Investigation of 64-QAM optical modulator with paralleled dual-drive MZMs
           driven by binary signals
    • Authors: Yupeng
      Abstract: Publication date: December 2017
      Source:Physical Communication, Volume 25, Part 2
      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: 2017-12-11T15:03:45Z
  • Energy allocation optimization for AF multi-hop in a cognitive radio
    • Authors: Imen Sahnoun; Ines Kammoun; Mohamed Siala; Ridha Hamila
      Abstract: Publication date: Available online 15 November 2017
      Source:Physical Communication
      Author(s): Imen Sahnoun, Ines Kammoun, Mohamed Siala, Ridha Hamila
      In this paper, novel optimal energy allocation schemes for the secondary users in an amplifiy-and-forward multi-hop underlay cognitive network are proposed. The optimization problem is formulated as a maximization of the instantaneous received signal to noise ratio, under interference power constraints that are imposed to protect the primary network. First, a novel geometrical approach is proposed for the two and three hop cases. Simulations show that the proposed approach combined with adaptive modulation outperforms the cooperative cognitive system with uniform energy distribution. Then, a Lagrange-based analytical approach solution is proposed to the problem for the 2-hop case. Numerical results show that the Lagrangian resolution leads to the same results as the geometrical one. The advantage of the geometrical approach is to get more insight for the 2-hop case and makes the resolution tractable for more hops in the network.
      Graphical abstract image

      PubDate: 2017-11-17T15:34:30Z
      DOI: 10.1016/j.phycom.2017.10.016
  • Analytical approximations for interference and SIR densities in terahertz
           systems with atmospheric absorption, directional antennas and blocking
    • Authors: Dmitri Moltchanov; Pavel Kustarev; Yevgeni Koucheryavy
      Abstract: Publication date: Available online 11 November 2017
      Source:Physical Communication
      Author(s): Dmitri Moltchanov, Pavel Kustarev, Yevgeni Koucheryavy
      Researchers face fundamental challenges applying the stochastic geometry framework to analysis of terahertz (THz) communications systems. The two major problems are the principally new propagation model that now includes exponential term responsible for molecular absorption and blocking of THz radiation by the human crowd around the receiver. These phenomena change the probability density function (pdf) of the interference from a single node such that it no longer has an analytical Laplace transform (LT) preventing characterization of the aggregated interference and signal-to-interference ratio (SIR) distributions. The expected use of highly directional antennas at both transmitter and receiver adds to this problem increasing the complexity of modeling efforts. In this paper, we consider Poisson deployment of interferers in ℜ 2 and provide accurate analytical approximations for pdf of interference from a randomly chosen node for blocking and non-blocking cases. We then derive LTs of pdfs of aggregated interference and SIR. Using the Talbot’s algorithm for inverse transform we provide numerical results indicating that failure to capture atmospheric absorption, blocking or antenna directivity leads to significant modeling errors. Finally, we investigate the response of SIR densities to a wide range of system parameters highlighting the specific effects of THz communications systems. The model developed in this paper can be used as a building block for performance analysis of realistic THz network deployments providing metrics such as outage and coverage probabilities.

      PubDate: 2017-11-17T15:34:30Z
      DOI: 10.1016/j.phycom.2017.10.018
  • Optimal transceiver design for SWIPT system with full-duplex receiver and
           energy-harvesting eavesdropper
    • Authors: Zhixiang Deng; Yuan Gao; Changchun Cai; Wei Li
      Abstract: Publication date: Available online 10 November 2017
      Source:Physical Communication
      Author(s): Zhixiang Deng, Yuan Gao, Changchun Cai, Wei Li
      In this paper, we consider simultaneous wireless information and power transfer (SWIPT) in a multiple-input-single-output (MISO) channel with a full-duplex (FD) receiver and an energy-harvesting (EH) receiver which is a potential eavesdropper, where the receivers adopt the power splitting approach to decode information and harvest energy simultaneously. The FD receiver decodes the information that should be kept secret from the EH receiver and sends jamming signals to degrade the eavesdropper simultaneously using the energy it harvests from the source. Taking into account the eavesdropper channel uncertainties, we attempt to maximize the worst-case secrecy rate (WCSR) at the receiver by jointly optimizing the information beamforming and energy covariance at the transmitter and the artificial noise (AN) covariance at the FD receiver, subject to the power constraint at the transmitter and the minimum energy required at the EH receiver. In order to solve this non-convex optimization problem, semidefinite relaxation (SDR) approach and extended S-procedure are explored to convert the original non-convex optimization problem to a convex one which can be solved efficiently. Numerical results are given to show the superiority of our proposed scheme.

      PubDate: 2017-11-17T15:34:30Z
      DOI: 10.1016/j.phycom.2017.10.017
  • A robust parameter estimation of FHSS signals using time-frequency
           analysis in a non-cooperative environment
    • Authors: Abdulrahman Kanaa; Ahmad Zuri Sha’ameri
      Abstract: Publication date: Available online 9 November 2017
      Source:Physical Communication
      Author(s): Abdulrahman Kanaa, Ahmad Zuri Sha’ameri
      Frequency hopping spread spectrum (FHSS) signals are widely implemented in both modern civilian and military applications. They are robust to channel impairments because of their low probability of interception. For applications that require the interception of FHSS signals, the signal parameters such as the hopping frequencies, hopping duration and hopping sequence should be accurately measured. In this paper, an accurate FHSS signal parameter estimation method is proposed based on quadratic time-frequency distributions (QTFDs). The extended modified B-distribution (EMBD) and the adaptive smoothed Wigner-Ville (SWWVD) are used which have the properties of high time-frequency resolution. The adaptive SWWVD requires no prior knowledge of the signal parameters since the kernel parameters are estimated from the signal characteristics and are compared to the EMBD which operates at the optimal kernel parameters. The proposed instantaneous frequency (IF) estimate method is compared to the time-frequency (TF) moments method and benchmarked with the Cramer-Rao lower bounds (CRLBs). The computational complexity of the IF estimation method is reduced by a factor of five compared to the TF moments method. Furthermore, the results show that the IF estimation method outperforms moments method where the mean-squared error (MSE) of the hopping frequencies estimate meets at minimum SNR of -3 dB and the hopping duration estimate MSE meets the CRLB at SNR of 0 dB.

      PubDate: 2017-11-10T13:02:14Z
      DOI: 10.1016/j.phycom.2017.10.013
  • 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
  • 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
  • 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
  • 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
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