IET Communications
Volume 10, Issue 9, 09 June 2016
Volumes & issues:
Volume 10, Issue 9
09 June 2016
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- Author(s): Jianhe Du ; Chaowei Yuan ; Pei Tian ; Heyun Lin
- Source: IET Communications, Volume 10, Issue 9, p. 995 –1002
- DOI: 10.1049/iet-com.2015.0907
- Type: Article
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In this study, the authors present a novel channel estimation algorithm for three-hop multi-input multi-output (MIMO) relay systems using the PARATUCK2 tensor model. At the destination, the proposed algorithm exploits a unified formulation of the received signal as a PARATUCK2 model, and jointly estimates all of the channel matrices involved in the communication. Compared with existing algorithms, the proposed algorithm only requires the source to transmit the channel training sequences, does not need relays to perform any task of channel estimation, and yields smaller estimation error. Moreover, the proposed algorithm can be extended to multi-hop MIMO relay systems with any number of hops. Numerical examples are shown to demonstrate the effectiveness of the PARATUCK2-based channel estimation algorithm.
- Author(s): Zan Li ; Fuhui Zhou ; Jiangbo Si ; Peihan Qi ; Lei Guan
- Source: IET Communications, Volume 10, Issue 9, p. 1003 –1011
- DOI: 10.1049/iet-com.2015.0654
- Type: Article
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1003
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Cooperative spectrum sensing, proposed to improve the performance of spectrum sensing in cognitive radio systems where there are multiple secondary users who can cooperatively detect the presence of one primary user, is receiving significant attention. However, few cooperative sensing algorithms take the correlation among the received primary user signals into account. A feasibly efficient cooperative spectrum sensing scheme based on Cholesky decomposition of the correlation matrix of the received signals is proposed. The ratio of the maximum eigenvalue to the minimum eigenvalue of the matrix obtained by Cholesky decomposition is used to construct the test statistic. Analytical approximations for the false alarm probability and decision threshold are derived using a moment matching method. The new scheme is in the category of blind cooperative spectrum sensing schemes requiring neither information about the primary user signal nor the channel nor the noise power. The new scheme can work better than the existing eigenvalue-based cooperative spectrum sensing methods in some conditions, and it has lower complexity.
- Author(s): Yu Xiong ; Xue Fan ; Shuming Liu
- Source: IET Communications, Volume 10, Issue 9, p. 1012 –1020
- DOI: 10.1049/iet-com.2015.0783
- Type: Article
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The finer spectrum granularity unit in elastic optical networks makes wider spectrum services more likely to be restricted by the constraints of spectrum continuity and spectrum contiguity (2SC), leading to higher blocking probability (BP). Obviously, it would deteriorate the fairness among multi-granularity services. Therefore, a fair dynamic routing and spectrum allocation algorithm is proposed. By virtualising the network resources as a ‘resource pool’, a two-dimensional rectangle packing model in combination with service holding-time is introduced to satisfy the 2SC constraints and to optimise the allocation of the ‘resource pool’ for dynamic multi-granularity services. Besides multi-granularity service fairness is achieved by tackling heterogeneous-size services together. Simulation results show that the benefit in terms of fairness can be reaped. Meanwhile, the authors also investigate the proposed algorithm's impact on performance metrics: namely, spectrum resource utilisation and BP. The results indicate that the proposed algorithm can achieve lower BP and higher spectrum efficiency.
- Author(s): Liwei Mu ; Zhiyong Liu ; Yi Fang
- Source: IET Communications, Volume 10, Issue 9, p. 1021 –1026
- DOI: 10.1049/iet-com.2015.0867
- Type: Article
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In this study, a family of time-invariant rate-compatible (RC) low-density parity-check (LDPC) convolutional codes with algebraic construction is developed based on the graph-extension method over a given positive integer m, which is considered as the given encoding memory. The base code of this family is first obtained by modifying a given construction of a time-invariant LDPC convolutional code. Afterwards, the authors derive the other extended component codes by successively adding extra information bits into the base code. In particular, each component code in the family not only enables the property of fast encoding that can dramatically reduce the implementation complexity, but has the given encoding memory m for each parity-check bit that can remarkably improve the error performance as well. They also demonstrate that the Tanner graph for all the codes in the family is free of girth 4. Simulation results indicate that the proposed family of RC-LDPC convolutional codes collectively offers a desirable performance improvement as compared with the existing counterparts over the binary-input additive Gaussian noise channels under BP decoding.
- Author(s): Renjian Feng ; Tongling Li ; Yinfeng Wu ; Ning Yu
- Source: IET Communications, Volume 10, Issue 9, p. 1027 –1034
- DOI: 10.1049/iet-com.2015.0884
- Type: Article
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Nodes in wireless sensor networks (WSNs) have the potential to be selfish without transmitting packets in routing. This study mainly focuses on the problem of reliable delivery mechanism in WSNs, and the authors’ objective is to ensure stable cooperation among nodes for packets delivery and minimum routing cost at the same time. Based on the performance metrics in terms of the rate of packets forwarding, correctly reporting event, and energy remain, the authors present a coalitional game model with a characteristic function to be shared among coalition members. Then an efficient and fast convergence coalition formation algorithm is proposed to obtain the stable coalition partition in the game. Finally, on the basis of the coalitional game model, the authors design a reliable coalition formation routing (RCFR) protocol, which selects route according to the principle of lowest cost. Simulation experiments are conducted to analyse the performance of RCFR, compared with original ad hoc on-demand distance vector routing and the method proposed by Kazemeyni. The results show that RCFR effectively enhances packet delivery ratio, decreases routing establishing time, balances energy consumption, and reduces average signalling overhead.
- Author(s): Hui Tian ; Wei Xie ; Xiaoying Gan ; Youyun Xu
- Source: IET Communications, Volume 10, Issue 9, p. 1035 –1043
- DOI: 10.1049/iet-com.2015.0866
- Type: Article
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In this study, a hybrid user association scheme for maximising energy efficiency is proposed in a wireless uplink heterogeneous network with human-to-human and machine-to-machine communications coexistence. Different from conventional user association algorithms, the authors consider access control protocol for both the human-type-communications (HTCs) users equipments’ (UEs) and machine-type-communications (MTCs) UEs according to their characteristics during user association phase, i.e. a contention-free access mechanism for HTC UEs and a random access based on access class barring mechanism for MTC UEs. They formulate the user association problem as a maximisation of the overall UEs’ energy efficiency in consideration of both the HTC and MTC UEs’ quality of service (QoS) guarantees and load balance among base stations simultaneously. To solve the problem, they propose a distributed iterative algorithm which adopts both the matching theory and the dual decomposition theory, and prove its convergence. Finally, simulation results show that their proposed user association scheme not only outperforms existing schemes in terms of the load balance and the overall energy efficiency but also achieves the same performance as exhaustive search in the case of less number of UEs, while satisfying both the HTC and MTC UEs’ QoS requirements.
- Author(s): Meng Zheng ; Wei Liang ; Haibin Yu ; Hamid Sharif
- Source: IET Communications, Volume 10, Issue 9, p. 1044 –1052
- DOI: 10.1049/iet-com.2015.0675
- Type: Article
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This study formulates a novel optimisation problem for joint spectrum sensing and random access control (JS 2 RAC) in cognitive radio sensor networks (CRSNs). The JS 2 RAC is formulated as a network utility maximisation problem, which aims to maximise the sum of utilities over all links in the network but subject to the primary user protection constraint, the energy constraint, and the physical constraint. Due to the non-separable and non-convex nature of the JS 2 RAC problem, the authors propose a primal-decomposition-based iterative (PDI) algorithm which decomposes the JS 2 RAC problem into a spectrum sensing subproblem and a random access control subproblem, and solve the two subproblems iteratively. Then, the authors prove the convergence of the PDI algorithm and show its distributed implementation in practice. Simulations demonstrate the fast convergence and the near-optimal nature of the PDI algorithm and show its significant improvement in the network utility of CRSNs in comparison with the method of optimising spectrum sensing and random access separately.
- Author(s): Jianxin Liao ; Lei Zhang ; Tonghong Li ; Jingyu Wang ; Qi Qi
- Source: IET Communications, Volume 10, Issue 9, p. 1053 –1062
- DOI: 10.1049/iet-com.2015.0539
- Type: Article
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Existing rateless codes have a very low intermediate symbol recovery rate. Therefore, a new analysis method named iterative and small degree first (I-SDF) is presented for the design of optimised partial recovery Luby transform codes (PR-LTC) in this study. On the basis of I-SDF, the required number of encoded symbols with degree d in each decoding step is calculated by an iterative optimisation algorithm. Under the proposed design, R(R < k) input symbols can be recovered from as few encoded symbols as possible in PR-LTC with message length k. Furthermore, multiple PR-LTC (M-PR-LTC) is proposed to recover several partial recovery point (PRPs) efficiently. The analysis process is divided into multiple stages, and the required number of encoded symbols with degree d in each decoding step is calculated by a cross-stage iterative optimisation algorithm. In addition, the interaction of each stage is adjusted by introducing a weight for each PRP. The PR-LTC and M-PR-LTC are evaluated and compared with the existing schemes. The simulation results demonstrate that PR-LTC and M-PR-LTC outperform other existing schemes in terms of average overhead, average degree of encoded symbols, memory usage, bit error rate and energy consumption.
- Author(s): Vandana Bassoo and Narvada Khedun
- Source: IET Communications, Volume 10, Issue 9, p. 1063 –1070
- DOI: 10.1049/iet-com.2015.1054
- Type: Article
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Through cognitive radio (CR), unlicensed users can occupy idle spectrum bands without interference with the primary user (PU). Generally, when the arrival rate of licensed users is high, secondary users (SUs) may starve. In this study, the authors propose two models to improve the average total waiting time for the SU. They are the M/D/1 model of a PU delay system with non-pre-emptive priority and pre-emptive priority. They are compared to an M/D/1 model with PU delay. Numerical analysis and Monte Carlo simulations are performed for all results. Improvements in the average total waiting time of 13–18% for PU and 24–32% for SU in the non-pre-emptive priority scheme are obtained. In the pre-emptive priority scheme, 19–22 and 5–7% improvements are obtained for the PU and SU respectively. Furthermore, same models, but with finite buffer capacity for both users are investigated to model a real-time system. In these schemes, the system improves the average total waiting time by 20–42% for the PU and 34–42% for the CR with the non-pre-emptive priority. Similarly, the pre-emptive model shows 25–44 and 6–24% reduction in the PU and SU waiting times respectively.
- Author(s): Peter Odero Akuon and Hongjun Xu
- Source: IET Communications, Volume 10, Issue 9, p. 1071 –1079
- DOI: 10.1049/iet-com.2015.0822
- Type: Article
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In this study, symbol error probability of transmitted modulation signals for a single-input–multiple-output system is used to derive overall average bit error probability (ABEP) of multiple active-spatial modulation (MA-SM) system as a function of the number density of bits in error. Specifically, a theoretic method of determining the number density of bits in error in the joint detector of MA-SM is proposed. Sample variance (SV) criterion uses the sample covariance of detector noise data, while mutual information (MI) criterion uses relative entropy derived from the Kullback–Liebler distance to compute the number density of bits in error. The choice for the better criterion is formulated as a model selection problem between the SV and the MI criteria. Analytical results for ABEP are tightly verified from simulations, which are carried out under arbitrarily correlated flat Rayleigh fading channels. Various data rates, antenna spacing and number of transmit and receive antenna configurations are tested, where it is also shown that SM is a special case of MA-SM. Moreover, a basis spectral efficiency (BSE) formula for MA-SM systems is proposed, which can be used to select a preferred antenna configuration without the need for simulations.
- Author(s): Shanding Xu ; Xiwang Cao ; Guangkui Xu
- Source: IET Communications, Volume 10, Issue 9, p. 1080 –1086
- DOI: 10.1049/iet-com.2015.0864
- Type: Article
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In this study, first the authors present a simplified representation of the Peng–Fan bounds on the periodic Hamming correlation of frequency-hopping sequence (FHS) sets, which may also be used to check the optimality of an FHS set with respect to the Peng–Fan bounds. Second, they propose a recursive construction of FHS sets from the known ones using some injective functions and the Chinese remainder theorem. It generalises the previous construction of optimal FHSs and FHS sets with composite lengths employing a given function. Without the limit of the specific function, their construction can produce new optimal FHSs and FHS sets that cannot be produced by the earlier construction. By choosing appropriate injective functions and known optimal FHSs and FHS sets, infinitely many new optimal FHSs and FHS sets can be recursively obtained.
- Author(s): Bahareh Nazari and Abbas Jamalipour
- Source: IET Communications, Volume 10, Issue 9, p. 1087 –1095
- DOI: 10.1049/iet-com.2015.0764
- Type: Article
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p.
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Cooperative communication significantly improves the performance of wireless systems. Transmission of signal in such a system can be accomplished by the help of intermediate relay nodes. However, due to the selfish nature of network nodes, an incentive mechanism is required to stimulate relay nodes to cooperate. On the other hand, the authors assume that the source nodes are ill-informed about channel conditions of the relay nodes, which may result in asymmetry of information. In this study, the authors propose a distributed power allocation and price assignment algorithm over cooperative wireless networks. The proposed solution aims to achieve optimum power allocation to the source nodes and best price of power at the relay nodes, in the presence of asymmetric channel state information. To this end, the authors combine contract theory and auction mechanism in order to provide the highest possible utility for both the source and the relay nodes. The proposed distributed approach benefits the source nodes by preventing the relay nodes from cheating behaviour. Additionally, it favours the relay nodes by letting them assign the final price of power. Finally, the authors present simulation results in order to demonstrate efficiency of the proposed distributed multi-user algorithm.
- Author(s): Arockia Bazil Raj Anthonisamy ; Padmavathi Durairaj ; Lancelot James Paul
- Source: IET Communications, Volume 10, Issue 9, p. 1096 –1103
- DOI: 10.1049/iet-com.2015.0717
- Type: Article
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Among various atmospheric effects, beam wandering is the main cause for the major power loss in free space optical communication (FSOC) which cannot be resolved without incorporating the beam wandering compensation (BWC) control. To prove this prerequisite, a 155 Mbps data transmission experimental setup is built with necessary optoelectronic components for the link range of 0.5 km at an altitude of 15.25 m. A neuro-controller is developed inside the field programmable gate array and used to stabilise the received beam at the centre of the detector plane so as to perfectly couple the power in the bucket to the optical detector. The Q-factor and bit error rate variation profiles are calculated using the signal statistics obtained from the eye-diagram. The performance improvements on the FSOC system due to the incorporation of BWC control are investigated and discussed in terms of various communication quality assessment key parameters.
- Author(s): Jianfeng Ding ; Lingge Jiang ; Chen He
- Source: IET Communications, Volume 10, Issue 9, p. 1104 –1110
- DOI: 10.1049/iet-com.2015.0668
- Type: Article
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In the area of interference management, many works have used interference alignment (IA) to tackle interference in heterogeneous networks (HetNets). However, few work has been done from the energy-efficiency (EE) aspect. In this study, the authors address the joint EE resource allocation and IA problem for HetNets where several femtocells underlay within the coverage of a macrocell, and take into account the service requirements of macro cell user (MU). A mixed integer and non-convex optimisation framework is adopted to investigate the EE maximisation problem which is a multi-dimensional resource management problem. To solve the problem, the authors propose a user scheduling scheme to determine the transmission sequence as well as encoding and decoding matrices for each user. Then an iterative power control algorithm is proposed to optimise the EE of the networks. Simulation results validate the convergence and performance of proposed scheme.
- Author(s): Shaojie Zhang ; Abdelhakim Senhaji Hafid ; Haitao Zhao ; Shan Wang
- Source: IET Communications, Volume 10, Issue 9, p. 1111 –1120
- DOI: 10.1049/iet-com.2015.1213
- Type: Article
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The tradeoff between increasing secondary users’ (SUs’) throughput and decreasing interferences to primary user (PU) is an important problem in cognitive radio networks. Joint design of sensing duration and frame duration has a crucial impact on both these two conflicting attributes but has not been studied yet. In this study, using a cross-layer approach, the authors investigate joint design of sensing duration and frame duration for the tradeoff. Specially, they consider that PU's traffic randomly changes within a secondary frame and multiple SUs contend to use the licensed channel based on widely used large/small-scale-backoff-based MAC protocols. By modelling more realistic PU's traffic, imperfect spectrum sensing in PHY and multiple SUs’ access contention in MAC, the authors reformulate the sensing-throughput tradeoff problem to maximise SUs’ throughput while restricting interference probability to PU under a tolerable level. Moreover, the optimal solution is analysed and a bi-dimensional search algorithm is presented. Simulation results show that the authors’ proposal achieves better throughput performance than conventional approaches. They also show how the optimal solution varies with received PU's signal-to-noise ratio and PU's traffic distribution.
- Author(s): Juan Cao ; Dongming Wang ; Xiaoxia Duan ; Jiamin Li ; Xiaohu You
- Source: IET Communications, Volume 10, Issue 9, p. 1121 –1129
- DOI: 10.1049/iet-com.2015.0765
- Type: Article
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This paper considers the uplink of a multicell multiuser multiple-input-multiple-output (MIMO) time-division duplexing system, where K mobile users in the target cell send their uncoded M-ary phase shift keying (M-PSK) signals to the target base station (BS) equipped with a linear minimum mean square error (MMSE) receiver in the presence of receiver antenna correlations. By employing the equivalent channel model, the uplink is analysed in terms of symbol error rate (SER), giving approximated closed-form expressions. The complicated functions of the SER can be simplified for the case where all the eigenvalues of the correlation matrix of the target BS are identical or distinct. It is proved that in the high signal to noise ratio (SNR) region, the SER is independent of the correlations between the BS antennas. And due to the existence of pilot contamination and intercell interference, the SER tends to a constant whose value is depended on the number of mobile users in each cell and the interference strength between the cells as well. Finally computer simulations are conducted to show that our approximated expressions have good performance in low SNR even for not large K.
Channel estimation for multi-input multi-output relay systems using the PARATUCK2 tensor model
Feasibly efficient cooperative spectrum sensing scheme based on Cholesky decomposition of the correlation matrix
Fairness enhanced dynamic routing and spectrum allocation in elastic optical networks
Construction of time-invariant rate-compatible-low-density parity-check convolutional codes
Reliable routing in wireless sensor networks based on coalitional game theory
Hybrid user association for maximising energy efficiency in heterogeneous networks with human-to-human/machine-to-machine coexistence
Utility-based opportunistic spectrum access for cognitive radio sensor networks: joint spectrum sensing and random access control
Design of optimised multiple partial recovery LT codes
Improving the quality of service for users in cognitive radio network using priority queueing analysis
Performance of multiple active-spatial modulation: information theoretic criteria over correlated Rayleigh fading channels
Recursive construction of optimal frequency-hopping sequence sets
Contract-auction based distributed resource allocation for cooperative communications
Performance analysis of free space optical communication in open-atmospheric turbulence conditions with beam wandering compensation control
Joint energy-efficient resource allocation and interference alignment for HetNets
Cross-layer aware joint design of sensing and frame durations in cognitive radio networks
Uplink symbol error rate analysis of multicell multiuser-multiple-input–multiple-output systems with minimum mean square error receiver under pilot contamination
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