IET Communications
Volume 10, Issue 3, 11 February 2016
Volumes & issues:
Volume 10, Issue 3
11 February 2016
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- Author(s): Longye Wang ; Xiaoli Zeng ; Hong Wen
- Source: IET Communications, Volume 10, Issue 3, p. 229 –234
- DOI: 10.1049/iet-com.2015.0075
- Type: Article
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An asymmetric zero-correlation zone (A-ZCZ) sequence pair set is a ZCZ sequence pair set consisting of multiple ZCZ sequence pair subsets. Two arbitrary sequence pairs which belong to different subsets should have a large zero cross-correlation zone (ZCCZ) in the A-ZCZ sequence pair set. Additionally, each subset is a typical ZCZ sequence pair set. The proposed A-ZCZ sequence pair sets can be generated based on interleaved technique from perfect sequence or perfect sequence pair of length P = Nmk with N ≥ 1, m ≥ 1, k > 1. The new A-ZCZ sequence pair sets are applied to quasi-synchronous code-division multiple-access (QS-CDMA) systems and it can hypothetically achieve larger ZCCZ than typical ZCZ sequence pair sets, as well as eliminating both multiple access and multipath interference in the QS-CDMA system.
- Author(s): Jose Martin Luna-Rivera ; Daniel Ulises Campos-Delgado ; Carlos A. Gutiérrez ; David H. Covarrubias-Rosales
- Source: IET Communications, Volume 10, Issue 3, p. 235 –244
- DOI: 10.1049/iet-com.2014.1063
- Type: Article
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The use of multiple transmit and receive antennas is widely recognised as an effective technology to boost the capacity of wireless communication systems. Moreover, the combination of multiple-input multiple-output (MIMO) systems with multicarrier code division multiple access (MC-CDMA) offers a strong alternative to satisfy the demand for high data rates with rigorous quality-of-service (QoS) restrictions. In this study, this paper applies a closed-loop pre-equalisation methodology under a unified framework for MIMO and MC-CDMA systems that satisfies the QoS target with a single-user-based detector while minimising the power of the pre-equalisation factors. It is of particular interest to investigate the impact and limitations of combining the robustness of the feedback scheme with the degrees of freedom available in the system, given in terms of the number of subcarriers and multiple antennas. The contribution of this work includes the derivation of the distributed and centralised optimal closed-loop pre-equalisation solutions under the MIMO–MC-CDMA structure. The results and analysis illustrate important gains in the form of power savings, enabled by the spatial diversity of the MIMO scheme.
- Author(s): Haitao Wu ; Qinyu Zhang ; Zhihua Yang ; Jian Jiao ; Yunhe Li ; Shushi Gu
- Source: IET Communications, Volume 10, Issue 3, p. 245 –252
- DOI: 10.1049/iet-com.2014.1184
- Type: Article
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245
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To improve the reliability of file transfer and shorten file transfer time in space communication, this study aims to provide an improved strategy for deferred negative acknowledgement (NAK) in Consultative Committee for Space Data Systems File Delivery Protocol (CFDP). Based on a theoretical analysis of the recommended deferred NAK, the authors propose a double retransmission deferred NAK strategy instead to guarantee the reliability of file transfer; the file transfer time is reduced significantly using fewer retransmission spurts. They make the performance comparisons of the recommended deferred NAK in CFDP with the authors’ proposed strategy under several typical scenarios. Numerical and simulation results show the effectiveness of the proposed strategy.
- Author(s): Pengbiao Wang ; Rong Li ; Chenglin Zhao ; Xiaokai Liu ; Yang Zhang
- Source: IET Communications, Volume 10, Issue 3, p. 253 –262
- DOI: 10.1049/iet-com.2015.0385
- Type: Article
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This study addresses the problem of interference mitigation in multi-cell time division duplex cellular networks with large-scale antennas. Network performance in such systems is hampered by pilot contamination effect, which results in the inter-cell interference. To mitigate the interference, the authors propose a space-time pilot design-based approach to jointly eliminate interference from both time domain and space domain. The authors’ space-time pilot design divides a cellular network into different groups which proceed channel estimation alternately in time. Moreover, a low-rate coordination assisted pilot assignment scheme is added into each cell group during its pilot phase. This pilot assignment scheme relies on the minimum mean square of the updated Bayesian channel estimation. It can make use of the second-order statistical information about the users' channel vectors within the same group to assign an identical pilot sequence to users that tend to interfere with each other at a lower level. On the basis of space-time pilot design, the base station can proceed the maximal ratio transmitting and maximal ratio combining. With rigorous theoretic proof, their joint approach is able to significantly decrease interference. Simulations verified its excellent performance promotion.
- Author(s): Wenchao Zhai ; Zan Li ; Jiangbo Si ; Jun Bai
- Source: IET Communications, Volume 10, Issue 3, p. 263 –271
- DOI: 10.1049/iet-com.2015.0343
- Type: Article
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p.
263
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Performance analysis is presented for the joint estimation of symbol timing, frequency offset, and phase offset with continuous-phase modulation. In this study, undesirable influences on parameters to be estimated, which arise from the inaccuracy of the already estimated parameters, are computed mathematically. Based on performance analysis, a conditional Cramer-Rao bound (CRB) is put forward, and a hypothesise is made that phase offset variance with frequency error present should match with the conditional CRB for any digital phase modulation. Moreover, the hypothesis is manifested by analysing the log-likelihood function in a more general mathematical manner. To alleviate the influences, a data-aided acquisition and phase-locked loop tracking algorithm is proposed. The results of Monte Carlo simulations are presented, showing good agreement with theoretical analysis. Simulation results also show that the proposed algorithm can improve performance in terms of phase error variance at the expense of a high signal-to-noise ratio threshold.
- Author(s): Shama Naz Islam
- Source: IET Communications, Volume 10, Issue 3, p. 272 –282
- DOI: 10.1049/iet-com.2015.0484
- Type: Article
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p.
272
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In this paper, we investigate the impact of channel estimation error on the achievable common rate and error performance of amplify and forward (AF) multi-way relay networks (MWRNs). Assuming lattice codes with large dimensions, we provide the analytical expressions for the end-to-end SNR at the users and obtain upper bounds on the achievable common rate for an AF MWRN. Moreover, considering binary phase shift keying (BPSK) modulation as the simplest case of lattice codes, we obtain the average bit error rate (BER) for a user in an AF MWRN. The analysis shows that the average BER is a linearly increasing function and the achievable common rate is a linearly decreasing function of the channel estimation error. On the other hand, the average BER decreases and the achievable common rate increases with increasing correlation between the true and the estimated channel. Also, we observe that the AF protocol is robust against increasing number of users in terms of error performance. We show that when the decoding user has better channel conditions compared to other users, AF relaying gives a better error performance and common rate. Finally, simulation results are provided to verify the validity of our analysis.
- Author(s): Binyue Liu ; Yong Cheng ; Qiaoqiao Zhou
- Source: IET Communications, Volume 10, Issue 3, p. 283 –291
- DOI: 10.1049/iet-com.2015.0655
- Type: Article
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p.
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In practical cellular communication systems, perfect channel state information is not available at the base stations. Assuming that the channel uncertainty is bounded within a known spherical region, the authors consider in this study robust rank-two multicast beamforming for multiple groups of users in multicell systems. Worst-case robust beamforming is designed to guarantee that the predefined signal-to-interference-plus-noise ratio targets of all users are met for any channel instance in the bounded region. The Alamouti code is employed to double the degrees of freedom in the beamformer design. The authors apply the semi-definite relaxation (SDR) technique to address the formulated non-convex robust rank-two beamforming problem. Analytical results show that the SDR is tight when the number of users in each multicast group is no more than two and the channel uncertainty is sufficiently small. Finally, extensive simulations are carried out to validate the proposed beamforming design and the analytical studies.
- Author(s): Datong Xu ; Pinyi Ren ; Li Sun ; Houbing Song
- Source: IET Communications, Volume 10, Issue 3, p. 292 –299
- DOI: 10.1049/iet-com.2015.0229
- Type: Article
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292
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Coordinated multi-point (CoMP) techniques can be utilised in several wireless systems, such as LTE-A and fifth generation. However, inter-user interferences (IEIs) and intra-user interferences (IAIs) may degrade the quality of service in joint transmission (JT), CoMP systems. To suppress these interferences, the authors design an interference mitigation scheme via interference alignment (IA) and channel diagonalisation (IMS-IACD), which is implemented through a local two-step precoder-and-receiver design process. First, IA is employed to force the IEIs of each user into the interfering space. Second, the IAIs of each user are effectively suppressed by channel diagonalisation with a selective method. Performance analyses show that the IMS-IACD is feasible in general JT scenarios. The IMS-IACD does not contain any iterative process and superabundant information interaction. The structure of receiver generated by the authors’ channel diagonalisation method is quite simple, so the energy consumption can be saved by using this receiver. Moreover, computational complexities of the IMS-IACD and traditional schemes are in the same order of magnitude, and simulation results illustrate that the IMS-IACD improves the bit error rates and data rates for users.
- Author(s): Meysam Mirzaee and Soroush Akhlaghi
- Source: IET Communications, Volume 10, Issue 3, p. 300 –308
- DOI: 10.1049/iet-com.2015.0208
- Type: Article
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This study discusses the secrecy rate of two-hop relay-assisted cooperative wiretap channels, incorporating multi-antenna amplify and forward relaying in the middle of transmission. In this regard, under the Gaussian code book assumption, three main scenarios including null-space beamforming (NSBF), rank-1 beamforming (RBF), and the so-called general rank beamforming (GRBF) are proposed to be employed at the relay where their achievable secrecy rates are studied. Accordingly, for NSBF, a closed-form solution is derived, whereas the corresponding optimisation problems are formulated for the remaining cases as a standard semi-definite programming problem. Though GRBF ranks the first in terms of the achievable secrecy rate, RBF exhibits favourable results with a much lower complexity, as the corresponding optimisation problem runs over a reduced dimension. Moreover, NSBF has a much lower complexity, as it provides an analytical solution at the expense of a decrease in the secrecy rate, and interestingly, it performs quite well when the number of eavesdroppers is less than that of the relay antennas.
- Author(s): Nader Mokari ; Pedram Hajipour ; Leila Mohammadi ; Parvin Sojoodi Sardrood ; Zahra Ghattan Kashani
- Source: IET Communications, Volume 10, Issue 3, p. 309 –315
- DOI: 10.1049/iet-com.2015.0191
- Type: Article
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p.
309
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Nowadays, with the advent of new services, the need for high transmission data rates is inevitable. Thus, to solve this problem, the simultaneous use of multiple antennas at the transmitter and the receiver is mandatory. On the other hand, due to limited resources, their allocation is essential. To allocate resources in satellite systems, multiple-input–multiple-output, orthogonal frequency division multiple access, and adaptive coding and modulation techniques can be simultaneously applied. In this study, the resource allocation for non-delay-sensitive services is evaluated. The proposed optimisation problem is to maximise the sum data rate under the upward transmission power constraint. The authors solve the considered optimisation problem via the dual decomposition methods for both continuous and discrete cases. Finally, through simulation, the proposed algorithms are investigated and confirmed.
- Author(s): Meixiang Zhang and Sooyoung Kim
- Source: IET Communications, Volume 10, Issue 3, p. 316 –326
- DOI: 10.1049/iet-com.2015.0730
- Type: Article
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316
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In this study, the authors propose an efficient universal soft demodulation method for M-ary phase shift keying (PSK) and quadrature amplitude modulation (QAM) schemes. The proposed method achieves the same performance as the Max-log method with much lower, linear-order complexity. The proposed demodulator recursively maps the detected symbol to a specific region in the first quadrant, so that finally there is only one constellation symbol left in the region, and thus it requires approximately one distance estimation per bit. The authors first derive the equations to estimate soft decision bit information for a few well-known M-ary PSK and QAM schemes, and subsequently present compact universal equations applicable to any M-ary PSK and QAM schemes, respectively. The simulation results reveal that the proposed method produces exactly the same performance as the Max-log method with greatly reduced computational complexity.
- Author(s): Atul Kumar and Pravas Ranjan Sahu
- Source: IET Communications, Volume 10, Issue 3, p. 327 –335
- DOI: 10.1049/iet-com.2015.0716
- Type: Article
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Differential chaos shift keying (DCSK) modulation-based transmit antenna selection (TAS) schemes are proposed to reduce the effect of signal fading with less hardware complexity at the receiver. The transmitter adopts DCSK modulation and employs multiple antennas, whereas the receiver can have single/multiple antennas. On the basis of receiver structure/specifications some TAS schemes are presented. In particular, for multiple transmit antennas and single receive antenna system DCSK-TAS scheme is proposed and for multiple transmit and multiple receive antenna system, two schemes, i.e. DCSK-joint antenna selection and DCSK-TAS/equal gain combining (DCSK-TAS/EGC), are proposed. The probability of error of the proposed schemes is numerically evaluated in the presence of perfect feedback and feedback error in Nakagami-m fading channels. The proposed schemes completely outperform the conventional DCSK scheme with one transmit and one receive antenna. The results show that the DCSK-TAS/EGC has the best error performance among the proposed schemes. Throughput of the proposed schemes is also presented and compared. The error performance of the proposed schemes are numerically evaluated and plotted for the parameters of interest. The simulation results verify the theoretical results.
- Author(s): Lei Wen ; Jing Lei ; Man Su
- Source: IET Communications, Volume 10, Issue 3, p. 336 –345
- DOI: 10.1049/iet-com.2015.0506
- Type: Article
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p.
336
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Joint sparse graph for code division multiple access systems (JSG-CDMA) combines multiple accessing (low-density signature) and forward error correction (low-density parity check code) techniques, and it achieves satisfactory performance under overloaded conditions. In this study, the authors carry on the research on the joint detection and decoding for JSG-CDMA, and analyse the syndrome effect of message passing on the JSG by the extrinsic information transfer (EXIT) chart. An improved algorithm for joint detection and decoding on the JSG-CDMA receiver is proposed, and the convergence behaviour of the algorithm is analysed by EXIT chart. Simulation results show that improved algorithm enhance the system performance significantly with a marginal increase of the computational complexity.
- Author(s): Mina Baghani ; Soroush Akhlaghi ; Valiulah Golzadeh
- Source: IET Communications, Volume 10, Issue 3, p. 346 –355
- DOI: 10.1049/iet-com.2015.0555
- Type: Article
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p.
346
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This study concerns two-hop transmission over relay-assisted block fading channels, assuming there is no direct link between transmission ends and the communication is carried out through using a relay. It is assumed that the channel gains from source-to-relay and relay-to-destination are known at the relay, while the source is unaware of channel gains. In this case, it is demonstrated that the best signalling method is using a multi-layer code at the first hop, while using a single-layer code at the second hop. Accordingly, the decode-and-forward (DF) and amplify-and-forward (AF) strategies at the relay are investigated, where for DF strategy under two special cases of peak power and average power constraints, the optimal power allocation policy across coding blocks are devised. Moreover, for AF strategy the optimal weight function maximising the average signal-to-noise ratio at the destination is derived. The simulation results for Rayleigh fading environment demonstrate the superiority of DF over AF in terms of the average achievable rate. More specifically, it is demonstrated that the broadcast approach in DF strategy under average power constraint closely follows the so-called broadcast cutset upper bound, thereby providing favourable results in such network.
Families of asymmetric sequence pair set with zero-correlation zone via interleaved technique
Performance analysis of closed-loop pre-equalisation for multiuser multiple-input multiple-output with multicarrier code division multiple access systems
Double retransmission deferred negative acknowledgement in Consultative Committee for Space Data Systems File Delivery Protocol for space communications
Joint interference mitigation approach using space-time pilot design in large-scale antenna systems
Performance analysis of a joint estimator for timing, frequency, and phase with continuous-phase modulation
Achievable rate and error performance of an amplify and forward multi-way relay network in the presence of imperfect channel estimation
Robust rank-two beamforming for multicell multigroup multicast
Precoder-and-receiver design scheme for multi-user coordinated multi-point in LTE-A and fifth generation systems
Achievable secrecy rate of wiretap channels incorporating multi-input–multi-output amplify and forward relaying
Resource allocation for non-delay-sensitive satellite services using adaptive coding and modulation–multiple-input and multiple-output–orthogonal frequency division multiplexing
Universal soft demodulation schemes for M-ary phase shift keying and quadrature amplitude modulation
Performance analysis of differential chaos shift keying modulation with transmit antenna selection
Improved algorithm for joint detection and decoding on the joint sparse graph for CDMA systems
Average achievable rate of broadcast strategy in relay-assisted block fading channels
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