for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> PHYSICS (Total: 818 journals)
    - ELECTRICITY AND MAGNETISM (9 journals)
    - MECHANICS (22 journals)
    - NUCLEAR PHYSICS (52 journals)
    - OPTICS (90 journals)
    - PHYSICS (587 journals)
    - SOUND (25 journals)
    - THERMODYNAMICS (33 journals)

PHYSICS (587 journals)

The end of the list has been reached or no journals were found for your choice.
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  [3177 journals]
  • Application of wavelet transform in spectrum sensing for cognitive radio:
           A survey
    • Authors: P.Y. Dibal; E.N. Onwuka; J. Agajo; C.O. Alenoghena
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): P.Y. Dibal, E.N. Onwuka, J. Agajo, C.O. Alenoghena
      Spectrum sensing is an important technological requirement in the quest to realize dynamic spectrum access (DSA) in today’s wireless world. Cognitive radio (CR) has been identified as an enabling technology that will considerably mitigate the effect of spectrum underutilization and cushion spectrum scarcity. But for this to happen, fast and accurate sensing technique must be developed. Quite a number of spectrum sensing techniques are available in literature, but these are not without inherent short comings. Recently, applications of wavelet techniques for spectrum sensing is receiving attention in the research community, this is attributed to its unique ability to operate both in the time and frequency domains and its suitability for wideband sensing. This paper takes a general look at the applications of wavelets in solving problems in science and engineering and then focused on its recent applications in spectrum sensing. Besides discussing the general spectrum sensing techniques in literature, the paper also discussed wavelet-based spectrum sensing, and its variants; pointing out the merits and limitations of each. It noted that, like any other sensing technique, wavelet-based technique has its strengths and weaknesses, hence, the advantages and disadvantages of this technique are also highlighted. Also, wavelet techniques in spectrum sensing was variously compared with existing wavelet sensing techniques; other spectrum sensing techniques; and existing wideband sensing techniques. Emerging research trends involving wavelets in wireless communications systems design are discussed while some challenges posed by wavelet techniques are mentioned. The paper is intended to provide necessary information and serve as a pointer to relevant literatures for researchers seeking information about wavelets and their applications in science and engineering and particularly in spectrum sensing for CR.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.comcom.2018.04.015
      Issue No: Vol. 28 (2018)
       
  • Downlink user association and uplink scheduling for energy harvesting
           users in software-defined mobile networks
    • Authors: Hassan Yeganeh; Javane Rostampoor
      Pages: 11 - 18
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Hassan Yeganeh, Javane Rostampoor
      In this paper we consider a heterogeneous network which consists of a macro base station and some pico base stations utilizing massive MIMO and MIMO techniques, respectively. A central software-defined mobile network (SDMN) controller is adopted in order to provide user association and energy scheduling. The users are considered battery limited and are capable of simultaneous wireless information and power transfer (SWIPT) in order to harvest energy and address the energy shortage issue. These users harvest energy from the received signals in the downlink and consume it via their uplink communications. This paper deals with the downlink user association by jointly optimizing the overall sum-rate of the network and the harvested energy by introducing an appropriate utility function. In this regard, the optimum user association and power splitting factor for each user are calculated via the downlink optimization stage. Then, the process of uplink scheduling is defined as choosing the best users in each time epoch to transfer data as well as optimizing their transmit power by solving Lyapunov drift-plus-penalty function. Simulation results are provided in order to confirm the optimality of the proposed algorithm in comparison with the previous user association and uplink scheduling approaches in terms of providing fairness and battery management among users.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.002
      Issue No: Vol. 28 (2018)
       
  • Secrecy energy efficiency optimization for MISO SWIPT systems
    • Authors: Xiaobo Zhou; Wenlong Cai; Riqing Chen; Linqing Gui; Feng Shu; Jinyong Lin; Shuo Zhang; Yijin Zhang
      Pages: 19 - 27
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Xiaobo Zhou, Wenlong Cai, Riqing Chen, Linqing Gui, Feng Shu, Jinyong Lin, Shuo Zhang, Yijin Zhang
      In this paper, we investigate the secrecy energy efficiency (SEE) optimization of the multiple-input single-output (MISO) system. First, transmission beamforming vector is designed to achieve the SEE maximization subject to the constraints of transmission power, minimum secrecy rate threshold and harvested energy threshold. The optimization problem belongs to the category of fractional optimization, which is non-convex and is very difficult to tackle. In order to solve the optimization problem, we propose an algorithm that can obtain a near-optimal solution, which consists of outer-tier and inner-tier iterations. For the outer-tier iteration, we first employ the Dinkelbach method to convert the fractional objective function into a polynomial form, and then transform the optimization problem into a difference of concave (DC) programming. For the inner-tier iteration, we employ the first-order Taylor expansion and successive convex approximation (SCA) method to solve the DC optimization problem. Then, we analyze the computational complexity of the proposed algorithm. In addition,we prove that the rank relaxation is tight. The simulation results show that the SEE performance of our proposed algorithm is obviously superior to that of secrecy rate maximization scheme and zero-forcing scheme.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.001
      Issue No: Vol. 28 (2018)
       
  • Switch-and-stay combining for energy harvesting relaying systems
    • Authors: Hai Huang; Junjuan Xia; Xin Liu; Zhenyu Na; Qinghai Yang; Hongbin Chen; Junhui Zhao
      Pages: 28 - 34
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Hai Huang, Junjuan Xia, Xin Liu, Zhenyu Na, Qinghai Yang, Hongbin Chen, Junhui Zhao
      In this paper, we study the switch-and-stay combining technique into the energy-harvesting relaying networks, where the relay obtains its transmit power from the source through wireless energy harvesting. The moderate shadow environments are applied, so that the data transmission from the source to the destination can go through the direct link. Although the conventional selection combining technique can exploit both the direct and relaying branches for data transmission, it has to require to know the channel parameters of both branches, and results into frequent branch switching. To solve these issues, switch-and-stay combining (SSC) is proposed into the energy-harvesting relaying networks, where the same branch keeps to be used for data transmission when it can support the transmission quality. The branch switching occurs only when the branch cannot support the transmission quality. We study the system transmission performance by deriving expression for the system analytical outage probability. We also provide the asymptotic outage probability when the transmit power is high, from which we obtain more insights on the system design, such as the system diversity order and the impact of parameters on the system performance. Simulation and numerical results are provided to validate the proposed studies in this paper.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.006
      Issue No: Vol. 28 (2018)
       
  • A new scheme of dynamic power allocation in wireless powered communication
    • Authors: Chengcheng Han; Li Chen; Huarui Yin; Guo Wei
      Pages: 35 - 44
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Chengcheng Han, Li Chen, Huarui Yin, Guo Wei
      In this article, we propose a new generalized selection transmit scheme (GSTS) for wireless powered communication (WPC), where data access point (DAP) is powered by energy access point (EAP) to communicate with wireless device (WD). Theoretically speaking, allocating all harvesting energy to the antenna with the best channel gain will achieve the optimal performance. While the harvesting energy is dynamic and may exceed the power limitation of single antenna, we should allocate the harvesting energy to the best antennas subset with the minimum number of antennas. That is GSTS. For GSTS, we derive the new closed-form probability density function (PDF) of signal to noise ratio (SNR). According to the derived PDF, the approximate outage probability is derived. In order to depict the trend of outage probability at high SNR area, the diversity order is derived. It is determined by the minimum one of the transmit antenna number of EAP and that of DAP. Besides, the influence of line-of-sight (LOS) component in wireless power transfer (WPT) is also discussed.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.002
      Issue No: Vol. 28 (2018)
       
  • Green energy driven cellular networks with JT CoMP technique
    • Authors: Abu Jahid; Abdullah Bin Shams; Md. Farhad Hossain
      Pages: 58 - 68
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Abu Jahid, Abdullah Bin Shams, Md. Farhad Hossain
      Concerns about global warming and increasing number of base stations (BSs) leading to rising energy consumption have prompted extensive research effort focusing on energy efficiency (EE) issue for cellular networks. As a result, cellular operators are increasingly deploying renewable energy (RE) sources in BSs as a promising way to reduce the on-grid consumption and operational expenditure. In this paper, we propose a novel framework on green energy driven cellular networks aiming to maximize the utilization of the green energy and minimize the grid energy consumption considering stochastic traffic demand profile. Each BS is equipped with renewable energy generators, such as solar panel along with a set of batteries as an energy storage device and also connected to commercial grid supply. In addition, joint transmission (JT) coordinated multi-point (CoMP) transmission technique is integrated with the proposed model for selecting the best serving BSs for a user equipment (UE). The prime goal is to quantify the EE of various selection schemes namely, distance based, SINR based and SINR–distance based JT CoMP techniques under the proposed network model. Provision of sleep mode approach in BSs is also considered. A thorough investigation in the downlink of LTE-Advanced (LTE-A) cellular system is carried out for evaluating EE performance of the proposed framework under a wide range of network settings. Numerical results validate the proposed network models demonstrating a considerable enhancement in network EE compared to other counterparts.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.008
      Issue No: Vol. 28 (2018)
       
  • Cross-layer design benchmark for throughput maximization with fairness and
           delay constraints in DCF systems
    • Authors: Zihao You; I-Tai Lu
      Pages: 69 - 77
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Zihao You, I-Tai Lu
      This paper proposes a cross-layer design for the stations (STAs) in a distributed coordination function (DCF) network. By selecting the modulation scheme, coding scheme, and packet length of each STA in the network, the design aims to maximize the total throughput of all the STAs and satisfy the minimum throughput requirement or delay requirement of each STA, thus addressing the fairness and delay issues. The proposed scheme applies to the system where each STA employs a contention based channel access mechanism, Furthermore, unlike the existing optimization schemes, it takes two important factors, changeable data rate and changeable packet error rate (PER), into consideration. Using an existing Markov chain model to predict the performance of the STAs, we propose an approach that updates the selection of each STA sequentially, thus avoiding the large complexity from the exhaustive search. Many issues are discussed based on the numerical results, including how the approximations in our design affect the processing time and result of the design, how the change of one STA affects the performance of the other STAs, how the minimum throughput constraints affect the fairness and total throughput, how to select these constraints to satisfy the delay requirements, etc.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.005
      Issue No: Vol. 28 (2018)
       
  • Improved RMS delay and optimal system design of LED based indoor mobile
           visible light communication system
    • Authors: Ram Sharma; A. Charan Kumari; Mona Aggarwal; Swaran Ahuja
      Pages: 89 - 96
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Ram Sharma, A. Charan Kumari, Mona Aggarwal, Swaran Ahuja
      The light emitting diode (LED) based lighting systems can be used for creation of the indoor communication network for sending information besides serving its main purpose of illumination. However, there are a number of impediments which are still under resolution in order to realize the full potential of such a system. In particular, the visible light communication (VLC) systems suffer due to high inter symbol interference (ISI) mainly on account of multi path propagation which impacts the spectral efficiency of the system. Besides ensuring ubiquitous coverage, it is also important to improve the system’s bandwidth within the indoor scenario. The optimal deployment of such systems may result in optimum resource utilization (LEDs and driver circuits etc.) to minimize the energy consumption and to achieve improved operational efficiency. In this paper, we propose two types of LED deployment strategies — centralized and distributed and compare their performances on the basis of average outage area ratio, effect of semi-angle, root mean square delay and data transmission rate. The hyper heuristic evolutionary algorithm (HypEA) has been implemented to optimize the performance of the systems to achieve full receiver mobility in the indoor environment. The experimental results show that the distributed deployment strategy is able to optimize the system performance significantly in comparison to centralized deployment strategy.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.003
      Issue No: Vol. 28 (2018)
       
  • MM-wave wideband propagation model for wireless communications in built-up
           environments
    • Authors: Anwar Jarndal; Khawla Alnajjar
      Pages: 97 - 107
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Anwar Jarndal, Khawla Alnajjar
      Millimeter-wave technology is promising for the next generation of wireless communication. An appropriate channel model for typical scenarios in a built-up environment is crucially needed for development of future technologies such as 5G. This paper presents an efficient millimeter wave wideband propagation model that can be used for analysis and design purposes. Unlike the commonly used two-ray and statistical models, the proposed model has higher reliability and accuracy to simulate the considered environment. The uniform theory of diffraction has been used to calculate the total received signal due to multi-reflection–diffraction for both linear and circular polarization. Mathematical formulas have been derived for each considered ray contribution in terms of the building dimensions and the distances between the building, mobile and transmitter. The model has been used to evaluate the performance of the communication system at 28 and 73 GHz based on signal fading characteristics and power delay profile, and the simulation results have been compared with other published works

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.011
      Issue No: Vol. 28 (2018)
       
  • Computationally and energy efficient symbol-level precoding communications
           demonstrator
    • Authors: Jevgenij Krivochiza; Juan Carlos Merlano-Duncan; Stefano Andrenacci; Symeon Chatzinotas; Björn Ottersten
      Pages: 108 - 115
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Jevgenij Krivochiza, Juan Carlos Merlano-Duncan, Stefano Andrenacci, Symeon Chatzinotas, Björn Ottersten
      We demonstrate forward link interference mitigation techniques in a precoded multi-user communication scenario for the efficient frequency reuse. The developed test-bed provides an end-to-end precoding demonstration, which includes a transmitter, a multi-beam satellite channel emulator and user receivers. Precoded communications allow efficient frequency reuse in multiple-input multiple-output (MIMO) channel environments, where several coordinated antennas simultaneously transmit to a number of independent receivers. We implement and demonstrate the new Symbol-Level Precoding (SLP) technique and benchmark it against Zero-Forcing and MMSE techniques in realistic transmission conditions. We show performance of the SLP in various MIMO channel conditions and outline the impact of the modified constellation by the SLP on a conventional receiver.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.009
      Issue No: Vol. 28 (2018)
       
  • A novel bidirectional half-duplex fronthaul system using MMW/RoF and
           analog network coding
    • Authors: Thu A. Pham; Lam T. Vu; Ngoc T. Dang
      Pages: 116 - 122
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Thu A. Pham, Lam T. Vu, Ngoc T. Dang
      A novel bidirectional half-duplex fiber-wireless fronthaul system is proposed in this paper. Bidirectional relaying transmission is deployed in both optical fiber and wireless link thanks to millimeter-wave radio over fiber (MMW/RoF) and analog network coding (ANC) techniques. The architecture of the proposed fronthaul system is simplified significantly since it requires only an optical fiber with a single wavelength and a wireless link with a single MMW frequency. The detailed architectures of the subsystems such as the central station, the remote antenna unit, and the remote radio head are also designed. Mathematical expressions for the performance analysis of the proposed fronthaul system are derived considering the effects of various physical layer impairments. The numerical results demonstrate not only the feasibility of our proposed system but also the gain in terms of throughput of ANC-based relaying compared to conventional and digital network coding (DNC)-based relaying.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.012
      Issue No: Vol. 28 (2018)
       
  • Joint relay-user selection in energy harvesting relay network with direct
           link
    • Authors: Chenchen Liu; Tiejun Lv
      Pages: 123 - 129
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Chenchen Liu, Tiejun Lv
      In this paper, a joint relay-user selection (JRUS) scheme is proposed for an amplify-and-forward full-duplex (FD) relay network which includes one source node, multi-relay node and multi-user node, and the direct link between the source node and the user node is considered to convey information. Each FD relay node is energy-constrained and the simultaneous wireless information and power transfer technology is employed to harvest energy. A power splitter at each FD relay node splits the received signals into two components for energy harvesting and information processing. The implementation of the proposed JRUS scheme includes two steps: (1) the optimal user node is selected according to signal-to-noise ratio of the direct link between the source node and the user nodes; (2) the optimal energy harvesting relay node with optimal power splitting (PS) factor is picked out based on signal-to-interference-plus-noise ratio of the relaying link. The outage probability of the investigated relay network with the JRUS scheme is derived. In order to characterize the diversity order, we further present the asymptotic outage probability at high SNR. Moreover, the optimal PS factor of each relay node is calculated by minimizing the outage probability of the reconstructed relay network. Finally, numerical results demonstrate the accuracy of our performance analysis and the efficiency of the proposed scheme.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.014
      Issue No: Vol. 28 (2018)
       
  • 5G-based green broadband communication system design with simultaneous
           wireless information and power transfer
    • Authors: Xin Liu; Xueyan Zhang; Min Jia; Lisheng Fan; Weidang Lu; Xiangping Zhai
      Pages: 130 - 137
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Xin Liu, Xueyan Zhang, Min Jia, Lisheng Fan, Weidang Lu, Xiangping Zhai
      In 5G communications, the increasing demand for high data rate and ubiquitous services has led to a large energy consumption in both transmitter and receiver. Wireless power transfer (WPT) has been proposed as an effective energy saving method. However, WPT and wireless information transfer (WIT) are often separated in a communication system. In this paper, a 5G-based green broadband communication system with simultaneous wireless information and power transfer (SWIPT) is proposed to combine WIT and WPT. In the system, the subband sets available for WIT and WPT are defined by two complementary spectrum marker vectors, and two independent frequency domain signals using different subband sets are achieved by calculating the inner product of spectrum marker vector, pseudo-random (PR) phase and power scaling vector. Time domain fundamental modulation waveform (FMW) is generated by doing inverse fast Fourier transform (IFFT) of the frequency domain signal. The data stream is modulated on the FMW for WIT, while the FMW for WPT is transmitted directly. The BER performance of the system is analyzed. A joint optimization unit has been deployed to maximize the system throughput by jointly optimizing subband sets and subband powers subject to the constraints of energy requirement and interference. The simulation results have shown the outstanding performance of the designed system.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.015
      Issue No: Vol. 28 (2018)
       
  • Photonic millimeter-wave bridge for multi-Gbps passive optical networks
    • Authors: Ivan Aldaya; Carolina Del-Valle-Soto; Gabriel Campuzano; Elias Giacoumidis; Rafael González; Gerardo Castañón
      Pages: 138 - 146
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Ivan Aldaya, Carolina Del-Valle-Soto, Gabriel Campuzano, Elias Giacoumidis, Rafael González, Gerardo Castañón
      Survivability is a critical requirement of optical communication networks that is typically addressed implementing path diversity. However, due to the elevated cost of fiber installation, this approach may prove prohibitively expensive in optical access networks. In this paper, a novel cost-efficient photonic millimeter (mm)-wave bridge is proposed, which converts passive optical network (PON) signals to radiofrequency signals at mm-wave bands. The performance of the mm-wave photonic bridge is numerically tested, revealing its feasibility to transmit a 2.5-Gbps PON with –55.6 dB wireless link gain (WLG) using the 81–86 GHz band and 10-Gbps PON with –35 dB at the 102–109.5 GHz band. The effect of fiber is also analyzed, showing that fiber cuts closer to the optical network unit degrades more the system performance.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.04.001
      Issue No: Vol. 28 (2018)
       
  • Wireless powered cooperative communications with direct links over
           correlated channels
    • Authors: Dan Deng; Minghui Yu; Junjuan Xia; Zhenyu Na; Junhui Zhao; Qinghai Yang
      Pages: 147 - 153
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Dan Deng, Minghui Yu, Junjuan Xia, Zhenyu Na, Junhui Zhao, Qinghai Yang
      In this paper, we investigate the impact of correlated channels on the wireless powered cooperative networks, where the direct links between the source and destination exist and are correlated with the relaying links. In the considered system, the time switching-based relaying protocol of simultaneous wireless information and power transfer is used. In order to enhance the system performance, a better branch between the relaying link and the direct link is selected. We evaluate the system transmission performance by deriving the closed-form expression on outage probability as well as the asymptotic results for the proposed scheme, in the high regime of transmit power. Based on the theoretical analysis, we investigate the effects of the system parameters, such as channel correlation coefficient, average channel fading power, energy harvesting coefficient and slot allocation coefficient, on the system outage probability. Numerical results are provided to verify the theoretical analysis.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.013
      Issue No: Vol. 28 (2018)
       
  • Coexistence in fourth generation digital subscriber lines: Experiment,
           modeling, and simulation results
    • Authors: Sanda Drakulić; Martin Wolkerstorfer; Driton Statovci
      Pages: 154 - 165
      Abstract: Publication date: June 2018
      Source:Physical Communication, Volume 28
      Author(s): Sanda Drakulić, Martin Wolkerstorfer, Driton Statovci
      The deployment of fourth generation digital subscriber line (DSL) technology (“G.fast”) will be gradual and it may therefore share the cable infrastructure with legacy DSL technologies such as Very high speed DSL transceivers 2 (VDSL2). We perform experiments on coexistence of G.fast with legacy VDSL2, highlighting the practical relevance of out-of-band leakage and aliasing. Furthermore, the differences in transmission parameters (e.g., carrier width and sampling rate) and asynchronous transmission results in inter-carrier and inter-symbol interference (ICSI). Previous work on modeling ICSI in the communication field focused on modeling only a subset of these effects. Hence, we analytically derive a simplified ICSI model, which notably includes the effects of aliasing, leakage, and worst-case symbol misalignment. Our results partially based on simulations show that a) neglecting ICSI potentially leads to significant bit-rate overestimation (e.g., 18 % in G.fast rates); and b) a G.fast start frequency of approximately 23 MHz may provide sufficient spectral separation with VDSL2 profile 17a transceivers.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.04.002
      Issue No: Vol. 28 (2018)
       
  • Dynamic scheduling for wireless multicast in massive MIMO HetNet
    • Authors: Xinran Zhang; Songlin Sun
      Pages: 1 - 6
      Abstract: Publication date: Available online 4 January 2018
      Source:Physical Communication
      Author(s): Xinran Zhang, Songlin Sun
      Consider a massive multiple input and multiple output (MIMO) heterogeneous network (HetNet) scenario where the macro base station is coupled with low-power nodes (LPNs) to provide wireless multicast transmission to user equipments (UEs) within a single macro cell. The Markov decision process (MDP) model is adopted to model the dynamic scheduling problem introduced by the mobility of UEs. With asymptotic conclusion for the massive MIMO multicast transmission, we propose a MDP-based off-line scheduling problem with determined system parameters and derive a linear programming (LP) model to solve the problem. As for the system with undetermined parameters, we adopt Q-learning algorithm to solve the optimal policy. To derive the low-complexity algorithm, the state aggregation method is utilized to build an series of sub-problems to estimate the original complex MDP problem. Finally we use the MDP Toolbox in MATLAB to run simulations to test the proposed algorithm. The performance of the proposed algorithm is shown and analyzed in details.

      PubDate: 2018-01-09T21:19:51Z
      DOI: 10.1016/j.phycom.2017.12.015
      Issue No: Vol. 27 (2018)
       
  • A new hybrid multicarrier transmission technique with iterative frequency
           domain detection
    • Authors: Telmo Fernandes; Andreia Pereira; Marco Gomes; Vitor Silva; Rui Dinis
      Pages: 7 - 16
      Abstract: Publication date: Available online 4 January 2018
      Source:Physical Communication
      Author(s): Telmo Fernades, Andreia Pereira, Marco Gomes, Vitor Silva, Rui Dinis
      The growing progress in wireless communication services led to a demand in high data rates, spectral efficiency and flexibility requirements. The Block-Windowed Burst Orthogonal Frequency Division Multiplexing (BWB-OFDM) technique has been recently proposed to face these demands. This technique employs smoother, non-rectangular windows, allowing a power spectral density similar to the filtered OFDM approach, thus achieving high spectral efficiency; also, it packs together several OFDM symbols, with the addition of a sole zero-padding to accommodate the multipath channel’s propagation delay, thereby improving power efficiency. However, BWB-OFDM has the same drawbacks of OFDM when transmitting over hostile channel conditions, namely the performance degradation due to deep fades associated to severe frequency-selective channels. This paper proposes a new Time Interleaved BWB-OFDM (TIBWB-OFDM) technique that performs interleaving on the time-samples of each BWB-OFDM block, creating a kind of diversity effect at the frequency domain, granting a much better resilience against deep inband fades, while keeping all the mentioned advantages of BWB-OFDM at the cost of no added complexity. Also, by regarding TIBWB-OFDM as a hybrid technique combining single-carrier and multicarrier characteristics, this paper also proposes the use of non-linear frequency domain equalizers based on the Iterative Block Frequency Domain Equalization (IB-DFE) concept for TIBWB-OFDM detection. It is shown that noteworthy improvements can be achieved in bit error rate (BER) performance compared to conventional OFDM schemes when employing typical zero-forcing (ZF) and minimum mean-square error (MMSE) linear equalizers.

      PubDate: 2018-01-09T21:19:51Z
      DOI: 10.1016/j.phycom.2017.12.014
      Issue No: Vol. 27 (2018)
       
  • Underwater acoustic communication using Doppler-resilient orthogonal
           signal division multiplexing in a harbor environment
    • Authors: Tadashi Ebihara; Geert Leus; Hanako Ogasawara
      Pages: 24 - 35
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Tadashi Ebihara, Geert Leus, Hanako Ogasawara
      Underwater acoustic (UWA) channels are one of the historical mobile ultrawideband channels characterized by large delay and Doppler spreads, but reliable UWA communication remains challenging. Here we performed an initial demonstration of the Doppler-resilient orthogonal signal division multiplexing (D-OSDM) technique in an actual sea environment. D-OSDM spreads data symbols in both time and frequency with guardbands to exploit the time and frequency diversity of UWA channels. The experiment was performed in a challenging scenario: the transmitter was fixed on a floating pier, and the receiver was mounted on a moving remote-controlled boat. The harbor UWA channel had a delay spread of 50 ms and a Doppler spread of up to 4.5 Hz, in the presence of additive Gaussian noise, and the combination of two Rayleigh fading models (a two-path model without Doppler spread and a multi-path model with Doppler spread) was able to successfully model the actual environment. Our results also confirmed that a UWA communication link using D-OSDM will deliver excellent reliability even for a harbor UWA channel with a mobile receiver; D-OSDM achieves better communication quality compared to other communication schemes in both simulations and experiments.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.001
      Issue No: Vol. 27 (2018)
       
  • Semi-cooperative game theoretic framework for resource allocation in
           cognitive cellular networks
    • Authors: Praful D. Mankar; Goutam Das; S.S. Pathak; Abhilash B. Ghanore
      Pages: 36 - 45
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Praful D. Mankar, Goutam Das, S.S. Pathak, Abhilash B. Ghanore
      Deployment of small cells beside macro cells has become the promising solution to meet the increasing service demand with limited bandwidth. However, the inter- and intra-tier interference limit the network capacity. Here, we present a semi-cooperative based resource allocation (SCRA) framework for cognitive small cells. The proposed framework allocates the underutilized spectrum of primary network for the downlink transmission of cognitive small cells such that the interference to primary users is below the threshold and the QoS (Quality of Service) of the associated user is satisfied. The game theoretic approach is adapted for distributed resource allocation where players (i.e. cognitive small cells) access primary channels in a non-cooperative manner. The utility of players is modeled as a negative weighted sum of the transmission power in the primary channels. We assume that the macro cell, after a specific interval of time, uses the primary users’ cooperation to obtain the channel weights for the players. We show that there exists the Nash Equilibrium (NE) in the proposed game of resource allocation. Finally, the performance of proposed SCRA enabled two-tier networks is demonstrated through extensive simulations.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.005
      Issue No: Vol. 27 (2018)
       
  • New adaptive link layer protocol using optimal packet length for free
           space optical communications
    • Authors: Ghassan Alnwaimi; Hatem Boujemaa
      Pages: 46 - 53
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Ghassan Alnwaimi, Hatem Boujemaa
      In this paper, the authors propose a new link layer protocol that adapts packet length and modulation and coding scheme (MCS) to propagation conditions for free space optical communications (FSO). In conventional FSO systems, only the MCS has been adapted with respect to propagation condition. For low signal to noise ratio (SNR), we reduce packet length and use robust modulation such as On Off Keying (OOK) and low rate channel coding. While, at high SNR, we increase packet length and use large modulation constellation. A significant enhancement in throughput is observed: the proposed link layer protocol offers 1–2 dB gain compared to the conventional one where all packets are transmitted with the same length.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.004
      Issue No: Vol. 27 (2018)
       
  • Effects of multiple co-channel interferers on the performance of
           amplify-and-forward relaying with optimum combining, multiple relays and
           multiple antennas
    • Authors: Henry W. Merino; Carlos E. Câmara; Celso de Almeida
      Pages: 54 - 62
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Henry W. Merino, Carlos E. Câmara, Celso de Almeida
      Cooperative relaying is a method used mainly to improve cellular networks in terms of diversity gain and coverage extension. However, its performance is gravely affected by the co-channel interference (CCI), especially when a high channel reuse is needed. Optimum combining (OC) is the combining technique that maximizes the signal-to-interference-plus-noise-ratio (SINR) and eliminates the CCI, achieving the best diversity gain. In the present paper, the performance analysis of cooperative amplify-and-forward relaying by using OC is extended for a scenario with multiple co-channel interferers, multiple-antenna relays and multiple antenna-destination. Also, the techniques of multiple relay transmission (MRT) and relay selection with transmit antenna selection (RS-TAS) are evaluated and compared. An approximation of the SINR and the diversity gain are obtained for both transmission techniques. The moment-generating function (MGF) of SINR is derived in order to obtain the average bit-error rate (BER) of the system. Analytical results are validated using Monte-Carlo simulations, which shows that the proposed scenario combats the CCI in a non obvious way and obtains diversity gain in both transmission techniques. Moreover, the MRT technique cancels a greater number of interferers than RS-TAS, while RS-TAS achieves better spectral efficiency and obtains better performance for small number of interferers.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.003
      Issue No: Vol. 27 (2018)
       
  • A network steganographic approach to overlay cognitive radio systems
           utilizing systematic coding
    • Authors: Amir Hossein Ghane; Jalil Seifali Harsini
      Pages: 63 - 73
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Amir Hossein Ghane, Jalil Seifali Harsini
      Network steganography is an information hiding technique that utilizes network protocols to facilitate hidden communication. The aim is to embed secret information bits into regular network traffic (as a carrier) so that confidential data can be transmitted covertly between two communicating parties. In this paper, the concept of network steganography is extended for overlay cognitive radio networks utilizing cooperative relaying protocols with systematic channel codes. In the considered model, the cognitive node relays the primary data according to a time-slotted decode-and-forward cooperative protocol with maximum-ratio combining (MRC) at the primary destination. We propose a steganographic approach in which the cognitive node embeds confidential cognitive data at the wavelet transform domain into primary data code words. In this approach, the embedding operation is designed to preserve the statistical properties of the cover data in terms of decoded BER after MRC decoding of code words at the destination node which includes both the effect of wireless channel errors and errors due to embedding distortion. From this point of view, the proposed scheme may be seen as a lossless steganography scheme that embeds secret data into coded data strings. We provided implementation examples using both systematic BCH and turbo channel coding. The results show that the proposed scheme can provide diversity gain using stego-based MRC at the primary receiver and covert confidential cognitive data communications simultaneously.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.008
      Issue No: Vol. 27 (2018)
       
  • On optimization of wireless XOR erasure codes
    • Authors: Jalaluddin Qureshi; Adeel Malik
      Pages: 74 - 85
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Jalaluddin Qureshi, Adeel Malik
      In this paper we study the problem of optimizing linear erasure codes over G F ( 2 ) for single-hop wireless multicasting. We first present an algorithmic optimization technique which minimizes the number of transmissions given the knowledge of packets received by each of the receivers. We show that the algorithmic optimization technique is equivalent to an NP-complete Boolean constraint satisfaction problem (CSP), using Schaefer’s dichotomy theorem. This makes the performance evaluation of such transmission network a difficult problem. We derive closed form expression and upper bound of minimum number of transmissions for restricted classes of the problem which sheds interesting insight about the behavior of optimal erasure codes over G F ( 2 ) . We also show that the greedy algorithm on the mapped Boolean SAT problem outperforms previously proposed state-of-the art heuristic coding algorithms, and its performance is virtually similar to the optimal maximum distance separable (MDS) code for network parameters of practical interest.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.007
      Issue No: Vol. 27 (2018)
       
  • Performance analysis of energy harvesting AF relay systems over Nakagami-m
           fading channels with co-channel interferences
    • Authors: Fangqing Tan; Yuan Ren
      Pages: 86 - 92
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Fangqing Tan, Yuan Ren
      In this paper, we present performance analysis for an energy harvesting amplify-and-forward relay system with multiple co-channel interferences (CCIs) at the relay and destination, over Nakagami- m fading Channels. Specifically, exact and asymptotic closed-form expressions are derived for outage probability of the considered relay system. In addition, we also obtain an efficient numerical expression for the ergodic throughput by exploiting Gauss–Chebychev quadrature formula. Finally, the optimal time ratio for maximizing the system’s ergodic throughput is studied numerically. The theoretical derivations are validated through Monte Carlo simulations. Through the asymptotic analysis, we show that the system diversity order is determined by the smaller channel fading severity parameters of the dual-hop desired transmission links, regardless of the fading channel parameters of CCIs.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.005
      Issue No: Vol. 27 (2018)
       
  • Joint resource optimization for DF relaying SWIPT based cognitive sensor
           networks
    • Authors: Hong Peng; Yuanrong Lin; Weidang Lu; Linfu Xie; Xin Liu; Jingyu Hua
      Pages: 93 - 98
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Hong Peng, Yuanrong Lin, Weidang Lu, Linfu Xie, Xin Liu, Jingyu Hua
      Spectrum and energy are two important resources for wireless sensor networks (WSNs). Cognitive Radio (CR) can improve the efficiency of spectrum utilization by allowing secondary users (SUs) access to the licensed bands as long as they do not significantly affect the performance of primary users (PUs). Simultaneous wireless information and power transfer (SWIPT) can harvest energy and decode information simultaneously from radio-frequency (RF) signal, which can prolong the life time of energy-constraint networks (e.g., WSNs). In this paper, we propose a joint resource optimization scheme in respect of transmission power and power splitting ratio for decode-and-forward (DF) relaying SWIPT based cognitive sensor networks (CSNs), where relay sensor node (RSN) harvests energy from the signal of source sensor node (SSN) by using power splitting (PS) receiver architecture and utilize the harvested energy to help forward SSNs information. We maximize the throughput of SUs while guaranteeing the interference to PUs caused by SUs is smaller than the interference threshold. Simulation results demonstrate the performance of the joint resource optimization scheme.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.003
      Issue No: Vol. 27 (2018)
       
  • Dynamic threshold-setting for RF-powered cognitive radio networks in
           non-Gaussian noise
    • Authors: Chengzhuo Shi; Zheng Dou; Yun Lin; Wenwen Li
      Pages: 99 - 105
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Chengzhuo Shi, Zheng Dou, Yun Lin, Wenwen Li
      The increasing demand for spectral and energy efficient communication networks has drawn an upsurge of interest in frequency (RF) energy harvesting (EH) cognitive radio networks (CRNs), and the spectrum analyzer is the brain to provide different spectral access and energy harvesting opportunities in wireless-powered cognitive radio networks (WP-CRNs). The performance of detecting the existence of primary signals will be more crucial for the EH node. However, to the best of our knowledge, no dynamic threshold-setting method to achieve target detection performance, particularly in the practical non-Gaussian noise, is reported in the literature. Traditional assumption of additive white Gaussian noise (AWGN) fails to model the behavior of certain types of noise found in practice. In this paper we give a dynamic threshold-setting method to detect the existence of primary signals for the energy harvesting node in non-Gaussian noise background. Combined with the fractional lower order statistics (FLOS), we propose a weighting factor for dynamic threshold-setting to exploit the existence of the PU to harvest RF energy, namely weighting factor based fractional lower order moment (WF-FLOM) detector. Numerical simulation results verify that the proposed method is effective for the EH node, when the signal-to-noise ratio is low or the back ground noise varies.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.001
      Issue No: Vol. 27 (2018)
       
  • Hybrid cognitive Gaussian two-way relay channel: Performance analysis and
           optimal resource allocation
    • Authors: Srinath Gunnery; Sadhana Mishra; Aditya Trivedi
      Pages: 106 - 115
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Srinath Gunnery, Sadhana Mishra, Aditya Trivedi
      Motivated by the deployment of hybrid cooperative cognitive radio (HCCR) based relays in cellular environments, this paper proposes the hybrid cognitive Gaussian two-way relay channel (HCGTWRC) model. Recently, the combination of licensed and cognitive radios with cooperative systems has gained popularity. These combined techniques have the potential to outperform primary network and pure cognitive network by utilizing the complementary nature of licensed and cognitive radios. In the proposed HCGTWRC model, a relay jointly utilizes both the licensed as well as the unlicensed/cognitive radio resources (RRs). Unlike conventional two-way relay channel, in this proposed model, source uses licensed resources for transmission and relay forwards this information using cognitive RRs. These licensed and unlicensed resources are not affected by total resource constraints of source and relay. Here, unlicensed RRs are not only described by bandwidth and power but also by reliability/availability parameter because of its opportunistic nature. In this paper, the proposed HCGTWRC model is studied by taking information theoretic aspect. In this respect, firstly, upper and lower bounds of performance metrics such as capacity, spectral efficiency (SE), and energy efficiency (EE) are analytically derived for the proposed HCGTWRC model. Then the optimal resource (such as power and bandwidth) allocation is derived with respect to upper and lower bounds of each performance metrics. Further, the performance comparison of the proposed HCGTWRC model is presented with the existing one. Numerical results are also presented for the optimal resource allocation to validate the analytical ones.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.006
      Issue No: Vol. 27 (2018)
       
  • Worst-case weighted sum-rate maximization in multicell massive MIMO
           downlink system for 5G communications
    • Authors: Sunil Chinnadurai; Poongundran Selvaprabhu; Xueqin Jiang; Han Hai; Moon Ho Lee
      Pages: 116 - 124
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Sunil Chinnadurai, Poongundran Selvaprabhu, Xueqin Jiang, Han Hai, Moon Ho Lee
      In this paper, we present a robust beamforming design to examine the weighted sum-rate maximization (WSRM) problem in a multicell massive MIMO downlink system for 5G communications. This work assume imperfect channel state information (CSI) by adding uncertainties to channel matrices with worst-case models i.e. singular value uncertainty model (SVUM) and ellipsoidal uncertainty model (EUM). In SVUM, WSRM problem is formulated subject to the transmit power constraints. While, the problem is devised in EUM by alternatively considering its dual power minimization problem subject to the worst-case signal-to-interference-plus-noise ratio (SINR) constraints for all mobile stations. The designed problem for both SVUM and EUM are known as non-deterministic polynomial (NP) problem which is difficult to solve. We propose an iterative algorithm established on majorization minimization (MM) technique that solves and achieves convergence to stationary point of these two problems. In EUM, the convergence point is obtained after converting the infinite number of SINR constraints into linear matrix inequalities (LMI) by employing S-Procedure. Extensive numerical results are provided to show that the proposed iterative algorithm significantly increases performance in terms of sum-rate and also attains faster convergence as compared with the conventional polynomial time algorithm.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.01.006
      Issue No: Vol. 27 (2018)
       
  • Performance analysis of scheduled STBC using statistical CSI under
           multiple interferers with different power in CR-MIMO systems
    • Authors: Donghun Lee
      Pages: 125 - 132
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Donghun Lee
      This paper studies the impact of the multiple interferers with different power on performance of a scheduled space–time block coding (STBC) using the statistical channel state information (CSI) in cognitive radio-multiple input multiple output (CR-MIMO) systems. This paper derives the exact closed-form cumulative density function (CDF) expression of the instantaneous post-processing signal to noise plus interference ratio (SINR) random variable at the user terminal of the proposed system. Using the derived CDF, the exact closed-form symbol error rate (SER) expression of the proposed system is derived for M -ary quadrature amplitude modulations (QAM). Further, this paper derives the exact closed-form expressions of outage probability and capacity for the proposed system. From the results, we know that the performance of the proposed system is saturated at different peak power constraint depending on the peak interference constraint. Also, the performance floor gets better by multi-user diversity and receive spatial diversity below the peak interference constraint in the presence of multiple interferers.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.007
      Issue No: Vol. 27 (2018)
       
  • LMMSE channel estimation for wireless energy harvesting AF relaying
    • Authors: Lumin Li; Minghe Mao; Ning Cao; Jie Li
      Pages: 133 - 142
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Lumin Li, Minghe Mao, Ning Cao, Jie Li
      Wireless energy harvesting can be adopted in relaying systems to solve the energy issue at the relay node. Channel estimation is an important aspect of its system design. Thus, in this paper, we study channel estimation for wireless energy harvesting relaying. In the study, we use the linear minimum mean squared error (LMMSE) estimators to estimate the source-to-relay link and the relay-to-destination link separately in an amplify-and-forward relaying system. Time-varying Rayleigh fading channels using the Jakes model are considered. Both time-switching (TS) and power-splitting (PS) energy harvesting strategies are examined. Fixed-gain relaying is compared with variable-gain relaying. The signal-to-noise ratios and the bit error rates are calculated. Numerical results are used to show that the system suffers from an error floor due to the use of LMMSE estimators and that its performance depends on several important system parameters. In particular, it is found that PS outperforms TS, variable-gain relaying is better than fixed-gain relaying, and a stationary relay can lead to better performance than a mobile relay. For PS, the choice of the PS factor is important. On the other hand, the symbol position has little effect on the BER.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.002
      Issue No: Vol. 27 (2018)
       
  • How to manage resources to provide physical layer security: Active versus
           passive adversary'
    • Authors: Mohammad Reza Abedi; Nader Mokari; Hamid Saeedi
      Pages: 143 - 149
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Mohammad Reza Abedi, Nader Mokari, Hamid Saeedi
      This paper studies the required physical (e.g. relays and jammers) and radio resources (e.g. power) to provide physical layer security for relay and friendly jammer assisted multiple-input and single-output transmissions in the presence of multiple active and passive adversaries. The passive adversaries are half duplex and only able to overhear the transmissions from the legitimate transmitter to the legitimate receiver, while the active adversaries are full duplex and able to jam and eavesdrop simultaneously. Since the channel information between adversaries and other nodes are uncertain, robust optimization methods are considered. In this regard, the main aim is to maximize the worst case secrecy rate subject to the normalized transmit power constraints of legitimate transmitter, friendly jammer and relay, and channel state information uncertainty constraints. Through several examples, we then investigate the required increase in physical and radio resources to maintain secure communication when passive adversaries upgrades themselves to active adversaries.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.004
      Issue No: Vol. 27 (2018)
       
  • Outdoor large-scale path loss characterization in an urban environment at
           26, 28, 36, and 38 GHz
    • Authors: M.N. Hindia; A.M. Al-Samman; T.A. Rahman; T.M. Yazdani
      Pages: 150 - 160
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): M.N. Hindia, A.M. Al-Samman, T.A. Rahman, T.M. Yazdani
      Most of the existing channel models cannot be applied to emerging millimeter-wave (mmWave) systems due to the difference between the characteristics of existing operating frequency bands and mmWave frequency bands. Thus, extensive studies on channel characterization and modeling are required to develop a general and suitable channel model that can accommodate a wide range of mmWave frequency bands in its modeling parameter. This paper presents a study of well-known channel models and their authentications for outdoor scenarios on the 26, 28, 36, and 38 GHz frequency bands. A new generalized path loss model for a range of mmWave frequency bands is proposed. Measurements for the outdoor line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios were taken every meter over a separation distance of 114 m between the TX and RX antenna locations to compare the well-known and the new large-scale generic path loss models. This outdoor channel characterization and modeling was conducted in Malaysia, which represents a tropical region environment, and the outcomes were investigated based on the proposed and the well-known path loss models for single- and multi-frequency schemes. Results show that the proposed model is simple and accurate in terms of frequency and environment signal attenuation. The path loss exponent values are 1.54 and 3.05 for the 20 GHz and 30 GHz bands, respectively.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.011
      Issue No: Vol. 27 (2018)
       
  • Space shift keying for multi-hop multi-branch networks
    • Authors: Ferhat Yarkin; Ibrahim Altunbas; Ertugrul Basar
      Pages: 161 - 169
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Ferhat Yarkin, Ibrahim Altunbas, Ertugrul Basar
      In this paper, we propose two different multi-hop multiple-input multiple-output (MIMO) space shift keying (SSK) schemes and investigate their error performance. In the first scheme, we consider a multi-hop multi-branch SSK system, in which the source and destination are equipped with multiple transmit and receive antennas, respectively. In this scheme, SSK is applied by using the source transmit antennas. Moreover, in each branch, single-antenna relays are used to amplify the transmitted signal from the source and forward it to the next relay until it reaches to the destination. In the second scheme, we consider a multi-hop MIMO-SSK system with path selection. In this scheme, the best path is selected among multiple branches and a multiple-antenna source communicates with a multiple-antenna destination via the relays of the selected path. Each relay is equipped with multiple transmit and receive antennas. Moreover, the source and all relays employ SSK modulation to transmit information bits and each relay in each path follows the decode-and-forward protocol. Approximate theoretical error probability expressions are derived for both schemes. Furthermore, an asymptotic symbol error probability performance analysis is also performed for the multi-hop MIMO-SSK system with path selection. It is shown that the proposed multi-hop SSK systems outperform conventional multi-hop M -PSK systems in terms of the error performance for especially high data rates and sufficient number of receive antennas at the receiving nodes.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.009
      Issue No: Vol. 27 (2018)
       
  • Benefits of the sparsity of mmWave outdoor spatial channels for
           beamforming and interference cancellation
    • Authors: Djamal E. Berraki; Simon M.D. Armour; Andrew R. Nix
      Pages: 170 - 180
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Djamal E. Berraki, Simon M.D. Armour, Andrew R. Nix
      Future outdoor communication networks are expected to make use of the mmWave bands. In this context, this paper investigates the use of sparse signal processing for efficient angular frequency estimation. Compressive sensing (CS) and correlation-based method are shown to provide accurate estimates of the Power Angular Profile (PAP). The recovered PAP is used to perform analogue beamforming. When tracking mobile users it is shown that codebook based analogue beamforming, as used in IEEE 802.11ad, results in a large signalling overhead. This adversely affects net throughput. Our CS approach requires just 2% of the resources consumed by codebook-based beamforming while providing similar SNR performance. Interference cancellation is implemented by exploiting the accurate PAP recovered by CS. This method estimates the beamforming vector required to optimise the signal to leakage and noise ratio (SLNR), allowing the coexistence of both non-interfering and interfering links. To maximise user fairness the interference cancellation capabilities of CS beamforming are combined with a Space–Time Division Multiple Access (STDMA) scheduling scheme. Considerable network throughput enhancement is demonstrated when compared to the IEEE 802.11ad codebook based beamforming approach.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.008
      Issue No: Vol. 27 (2018)
       
  • A novel energy-balanced routing algorithm in energy harvesting sensor
           networks
    • Authors: Feng Li; Mudi Xiong; Li Wang; Hong Peng; Jingyu Hua; Xin Liu
      Pages: 181 - 187
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Feng Li, Mudi Xiong, Li Wang, Hong Peng, Jingyu Hua, Xin Liu
      In energy harvesting wireless sensor networks, despite the network lifetime can be prolonged through node’s energy collection, how to enhance energy efficiency and optimize routing protocol are still critical and challenging due to volatility and uncertainty of energy harvesting. In this paper, we propose a novel routing method in energy harvesting sensor networks by taking into account the outage probability of relay transmission and node’s residual energy. Our goal is to achieve a balanced-based routing algorithm with improved transmission performance. We design an optimal power control strategy to optimize the outage probability for bidirectional sub-channels in energy harvesting sensor networks. Then, we raise a rational objective function to address the concerns of high efficient and balanced energy consumption in searching router. The main routine of the proposed routing algorithm is also given. Numerical results are provided to testify the performances of our proposed method from the perspectives of network lifetime and outage probability.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.010
      Issue No: Vol. 27 (2018)
       
  • Interference alignment with iterative channel estimation for the
           reciprocal M×2 MIMO X Network
    • Authors: Sudheesh P.G.; Maurizio Magarini; Palanivel Muthuchidambaranathan
      Pages: 188 - 196
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Sudheesh P.G., Maurizio Magarini, Palanivel Muthuchidambaranathan
      This paper investigates an interference alignment (IA) scheme for a reciprocal multi-input multi-output (MIMO) M × 2 X network where the knowledge of channel state information (CSI) is required. In our proposed approach, singular vectors, calculated from the singular value decomposition (SVD) of channel matrices, are used to compute precoding and zero-forcing (ZF) decoding matrices at transmitters and receivers, respectively. The orthogonality between precoding and decoding vectors that results from SVD is an advantage for realizing IA scheme because we can rely on an iterative scheme, known as iterative power method (IPM). The singular vectors resulting from the IPM approach converge to the actual ones after multiple iterations assuming a common “virtually static” channel between each link. However, due to the fast fading nature of the channel, computed precoding and ZF decoding vectors will be different from those resulting from the SVD of the actual channel. To this end, the IPM applied to get an estimate of precoding and ZF decoding vectors allows a better tracking of the time-varying channel. The bit error rate of the proposed scheme is evaluated by means of Monte Carlo simulations and compared with that achieved by a perfect CSI based system.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.013
      Issue No: Vol. 27 (2018)
       
  • Energy efficiency optimization for SWIPT in K-user MIMO interference
           channels
    • Authors: Huimin Zhao; Zujun Liu; Yongjun Sun
      Pages: 197 - 202
      Abstract: Publication date: April 2018
      Source:Physical Communication, Volume 27
      Author(s): Huimin Zhao, Zujun Liu, Yongjun Sun
      In this paper, we investigate the energy efficiency (EE) for K -user multiple-input multiple-output (MIMO) interference channels with simultaneous wireless information and power transfer (SWIPT) and interference alignment (IA). Specifically, power splitting architecture is leveraged at each receiver for information decoding (ID) and energy harvesting simultaneously. Taking the quality of service (Qos) requirement and harvested power constraints into consideration, we maximize the system EE by jointly designing transmit beamformers, transmit power, power splitters and receive filters. To solve the nonconvex EE optimization problem, we first eliminate the interference among users for ID via the maximal signal to interference plus noise ratio (Max-SINR) IA method, which yields a two-dimensional EE optimization problem. And then, we propose an EE-Max algorithm coupled with the Max-SINR, nonlinear fraction programming and one dimension searching to solve the reformulated problem. Simulation results show the effectiveness of the proposed EE optimization algorithm and reveal the influence of the maximum transmit power constraint and the QoS requirement on the system EE.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.02.012
      Issue No: Vol. 27 (2018)
       
  • Design of incentive scheme using contract theory in energy-harvesting
           enabled sensor networks
    • Authors: Linqing Gui; Yun Shi; Wenlong Cai; Feng Shu; Xiaobo Zhou; Tingting Liu
      Abstract: Publication date: Available online 8 April 2018
      Source:Physical Communication
      Author(s): Linqing Gui, Yun Shi, Wenlong Cai, Feng Shu, Xiaobo Zhou, Tingting Liu
      Wireless energy harvesting (EH) has been proven to be a promising technique for sensor networks to enhance self-sustainability and robustness. Due to the popularity and the inherent mobility, mobile phones will become excellent EH sources for sensor nodes, especially when sensor nodes cannot harvest energy from other fixed ambient sources. In order to motivate ambient mobile phones to transfer power, incentive mechanisms should be provided. Therefore in this paper, a contract-theory based incentive scheme is proposed. Compared to relevant incentive schemes, the proposed scheme not only overcomes the information asymmetry problem caused by privacy-protection nature of mobile users, but has also taken some important characteristics (e.g., time cost of users and remaining capacity of batteries) of mobile users into consideration. Simulation results have shown the feasibility of the proposed contract as well as the effectiveness of the proposed incentive scheme.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.016
       
  • Statistical analysis and performance evaluation of optical array receivers
           for deep-space optical communications under random tracking errors
    • Authors: Ali J. Hashmi; Ali A. Eftekhar; Ali Adibi; Farid Amoozegar
      Abstract: Publication date: Available online 28 March 2018
      Source:Physical Communication
      Author(s): Ali J. Hashmi, Ali A. Eftekhar, Ali Adibi, Farid Amoozegar
      Telescope array receiver is a viable architecture for Earth-based reception in a deep-space optical communication system. In this paper, effects of random tracking errors on the performance of optical array receivers for an inter-planetary deep-space optical communications link between Earth and Mars is investigated. The paper has two major parts. In the first part, statistical analysis and mathematical modeling of the impact of tracking errors on general direct-detection optical communication receivers is presented. The analytical results show that tracking errors could severely degrade the performance of optical receivers; hence, these need to be compensated, especially in a deep-space link. In the second part, design and analysis of a closed-loop tracking subsystem for telescope array receivers operating in a deep-space link is presented. An end-to-end simulation platform for communication between Earth and Mars is implemented that incorporates direct-detection array receivers and the proposed tracking subsystems to alleviate the effects of random tracking errors. Extreme channel conditions, i.e., maximum distance, strong background noise and turbulence conditions are modeled to evaluate the performance bounds. Simulations results depict that in worst-case channel conditions, the proposed architecture mitigates the impact of tracking errors to be within reasonable limits. Comparison of achievable data rates show that in the presence of random tracking errors, replacement of a large telescope (10m diameter) with an array of relatively smaller-sized telescopes (i.e., 100, 1m telescopes) results in acceptable performance loss (i.e., <13%). Hence, performance degradation due to tracking errors does not pose a major limitation in employing array architecture in deep-space communication. The presented analysis further strengthens the viability of array architecture compared to a monolithic, large telescope for deep-space communications.

      PubDate: 2018-04-15T10:46:50Z
      DOI: 10.1016/j.phycom.2018.03.010
       
  • 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)
       
  • Analysis and optimization of energy harvesting AF relaying with channel
           estimation
    • 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
       
  • 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
       
  • 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
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 54.161.45.156
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-