The Experts below are selected from a list of 22008 Experts worldwide ranked by ideXlab platform
Victor C M Leung - One of the best experts on this subject based on the ideXlab platform.
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interference alignment and soft space reuse based Cooperative Transmission for multi cell massive mimo networks
IEEE Transactions on Wireless Communications, 2018Co-Authors: Shun Zhang, Nan Zhao, Victor C M LeungAbstract:As a revolutionary wireless Transmission strategy, interference alignment (IA) can improve the capacity of cell-edge users. However, the acquisition of the global channel state information for IA leads to unacceptable overhead in the massive MIMO systems. To tackle this problem, in this paper, we propose an IA and soft-space-reuse (IA-SSR)-based Cooperative Transmission scheme under the two-stage precoding framework. Specifically, the cell-center and the cell-edge users are separately treated to fully exploit the spatial degrees of freedoms. Then, the optimal power allocation policy is developed to maximize the sum-capacity of the network. Next, a low-cost channel estimator is designed for the proposed IA-SSR framework. Some practical issues in IA-SSR implementation are also discussed. Finally, plenty of numerical results are presented to show the efficiency of the proposed algorithm.
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interference alignment and soft space reuse based Cooperative Transmission for multi cell massive mimo networks
arXiv: Information Theory, 2017Co-Authors: Shun Zhang, Nan Zhao, Victor C M LeungAbstract:As a revolutionary wireless Transmission strategy, interference alignment (IA) can improve the capacity of the cell-edge users. However, the acquisition of the global channel state information (CSI) for IA leads to unacceptable overhead in the massive MIMO systems. To tackle this problem, in this paper, we propose an IA and soft-space-reuse (IA-SSR) based Cooperative Transmission scheme under the two-stage precoding framework. Specifically, the cell-center and the cell-edge users are separately treated to fully exploit the spatial degrees of freedoms (DoF). Then, the optimal power allocation policy is developed to maximize the sum-capacity of the network. Next, a low-cost channel estimator is designed for the proposed IA-SSR framework. Some practical issues in IA-SSR implementation are also discussed. Finally, plenty of numerical results are presented to show the efficiency of the proposed algorithm.
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energy efficient relay selection for Cooperative relaying in wireless multimedia networks
IEEE Transactions on Vehicular Technology, 2015Co-Authors: Zhengguo Sheng, Victor C M Leung, Jun Fan, Chi Harold Liu, Xue Liu, Kin K. LeungAbstract:In existing wireless networks, supporting multimedia services are becoming more popular and important. In general, wireless multimedia networks should require energy efficiency and reliable Transmission while keeping satisfactory quality of services. In this respect, Cooperative communications have been considered as an efficient approach to address these demands by offering significant diversity gains over single-antenna systems without increasing requirements on radio resources. In this paper, we propose a power-allocation method to optimize the decode-and-forward (DF) Cooperative Transmission for source and relay nodes as a means to reduce the total power consumption, while maintaining the required quality of services, and investigate fundamental characteristics of Cooperative Transmission in terms of power efficiency. Moreover, for a network with multiple Cooperative nodes, we also propose an energy-efficient relay selection rule to offer fairness at each node and implement it into a practical routing protocol. Our performance analysis is supplemented by simulation results to illustrate significant energy savings of the proposed methods.
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distributed relay selection and power control in cognitive radio networks with Cooperative Transmission
International Conference on Communications, 2010Co-Authors: F R Yu, Hong Ji, Victor C M LeungAbstract:In this paper, we present a distributed relay selection and power allocation scheme concurrently considering the channel states of all related links and residual energy state of the relay nodes for Cooperative Transmission in cognitive radio (CR) networks. Specifically, we formulate the CR network with Cooperative Transmission as a restless bandit system, which has been widely applied in operations research and stochastic control. The channel state and residual energy state are presented by finite state Markov chains. With this stochastic optimization formulation, the optimal policy for relay selection and power allocation is indexable, meaning that the relay with the highest index should be selected. The proposed scheme can achieve the tradeoff between achievable rate and network lifetime. Simulation results are presented to illustrate the performance of the proposed scheme.
Kin K. Leung - One of the best experts on this subject based on the ideXlab platform.
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energy efficient relay selection for Cooperative relaying in wireless multimedia networks
IEEE Transactions on Vehicular Technology, 2015Co-Authors: Zhengguo Sheng, Victor C M Leung, Jun Fan, Chi Harold Liu, Xue Liu, Kin K. LeungAbstract:In existing wireless networks, supporting multimedia services are becoming more popular and important. In general, wireless multimedia networks should require energy efficiency and reliable Transmission while keeping satisfactory quality of services. In this respect, Cooperative communications have been considered as an efficient approach to address these demands by offering significant diversity gains over single-antenna systems without increasing requirements on radio resources. In this paper, we propose a power-allocation method to optimize the decode-and-forward (DF) Cooperative Transmission for source and relay nodes as a means to reduce the total power consumption, while maintaining the required quality of services, and investigate fundamental characteristics of Cooperative Transmission in terms of power efficiency. Moreover, for a network with multiple Cooperative nodes, we also propose an energy-efficient relay selection rule to offer fairness at each node and implement it into a practical routing protocol. Our performance analysis is supplemented by simulation results to illustrate significant energy savings of the proposed methods.
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On the application of Cooperative Transmission to secrecy communications
IEEE Journal on Selected Areas in Communications, 2012Co-Authors: Zhiguo Ding, Dennis L. Goeckel, Kin K. Leung, Don TowsleyAbstract:Information theoretic security has recently emerged as an effective physical layer approach to provide secure communications. The outage performance of such a secrecy communication system is considered in this paper, since it is an important criterion to measure whether users' predefined quality of service can be met. Provided that the legitimate receiver and eavesdropper have the same noise power, many existing secure schemes cannot achieve outage probability approaching zero, regardless of how large the Transmission power is. By introducing Cooperative Transmission into secrecy communication systems, it will be shown here that outage probability approaching zero can be achieved. In particular, scenarios with single-antenna nodes and multiple-antenna nodes will both be addressed, and the optimal design of beamforming/precoding will be investigated. Explicit expressions of the achievable outage probability and diversity-multiplexing tradeoff will be developed to demonstrate the performance of the proposed Cooperative secure Transmission schemes, and numerical results are presented.
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linear precoded Cooperative Transmission protocol for wireless broadcast channels
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Chee Yen Leow, Zhiguo Ding, Kin K. LeungAbstract:In multiple-input-single-output (MISO) broadcast channels, the achievable diversity gain is limited by the number of source transmitter antennas. Cooperative Transmission is able to provide another dimension of diversity gain improvement. In this paper, we introduce a spectrally efficient Cooperative Transmission protocol in MISO broadcast channels using linear precoding and nonorthogonal relaying. The proposed protocol can achieve maximum diversity gain expressed as the sum of the number of source transmitter antennas and the number of available relays. The diversity and multiplexing tradeoff of the proposed protocol outperforms the nonCooperative scheme, even when only a single relay is used. For a large number of relay candidates, the diversity and multiplexing tradeoff of the proposed protocol completely surpasses the existing nonCooperative scheme.
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cross layer routing using Cooperative Transmission in vehicular ad hoc networks
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Zhiguo Ding, Kin K. LeungAbstract:Wireless vehicular ad hoc networks are characterized by multi-hop Transmission, where a key problem is the design of routing, e.g., how to efficiently direct the information flow from the source to the destination via available intermediate nodes. In this paper, cross-layer routing is studied by applying Cooperative Transmission and a new strategy of path selection is proposed to achieve a better tradeoff between the Transmission power consumption and end-to-end reliability. The influence of Cooperative Transmission to the wireless link cost is first studied, which shows that the quality of wireless links could be improved significantly. Then we focus on formulating the objective functions for the addressed cross-layer optimization problem. Specifically, according to different quality of service requirements, two different types of routing optimization are investigated to understand the effects of improved link cost to the routing decision. The closed-form expressions of the optimal solutions for two addressed optimization problems are developed and later used as quantitative criteria of the routing decision. Our developed analytical and simulation results show that the criteria using Cooperative Transmission typically yield more efficient routes than the comparable schemes in terms of end-to-end reliability and total Transmission power.
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on the application of Cooperative Transmission to wireless broadcast channels
International Conference on Communications, 2010Co-Authors: Zhiguo Ding, Dennis L. Goeckel, Kin K. Leung, Don TowsleyAbstract:In this paper, we study the application of Cooperative diversity to wireless broadcast channels, a fundamental building block of wireless communication networks. Several Cooperative broadcast protocols will be proposed, and information theoretic metrics are developed to facilitate performance evaluation. Provided that there is no direct S-D link, the proposed protocols can achieve a multiplexing gain close to one, whereas the traditional two-hop scheme can only achieve the diversity gain 1/2. Provided that there are direct S-D links, the proposed protocol can still outperform the comparable scheme, particularly at high multiplexing gains.
Zhiguo Ding - One of the best experts on this subject based on the ideXlab platform.
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application of non orthogonal multiple access in Cooperative spectrum sharing networks over nakagami m fading channels
IEEE Transactions on Vehicular Technology, 2017Co-Authors: Zhiguo Ding, Jian ChenAbstract:This paper proposes a novel non-orthogonal multiple access (NOMA)-based Cooperative Transmission scheme for a spectrum-sharing cognitive radio network (CRN), whereby a secondary transmitter (ST) serves as a relay and helps transmit the primary and secondary messages simultaneously by employing NOMA signaling. This cooperation is particularly useful when the ST has good channel conditions to a primary receiver but lacks the radio spectrum. To evaluate the performance of the proposed scheme, the outage probability and system throughput for the primary and secondary networks are derived in closed forms. Simulation results demonstrate the superior performance gains for both networks thanks to the use of the proposed NOMA-based Cooperative Transmission scheme. It is also revealed that NOMA outperforms conventional orthogonal multiple access (OMA) and achieves better spectrum utilization.
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On the application of Cooperative Transmission to secrecy communications
IEEE Journal on Selected Areas in Communications, 2012Co-Authors: Zhiguo Ding, Dennis L. Goeckel, Kin K. Leung, Don TowsleyAbstract:Information theoretic security has recently emerged as an effective physical layer approach to provide secure communications. The outage performance of such a secrecy communication system is considered in this paper, since it is an important criterion to measure whether users' predefined quality of service can be met. Provided that the legitimate receiver and eavesdropper have the same noise power, many existing secure schemes cannot achieve outage probability approaching zero, regardless of how large the Transmission power is. By introducing Cooperative Transmission into secrecy communication systems, it will be shown here that outage probability approaching zero can be achieved. In particular, scenarios with single-antenna nodes and multiple-antenna nodes will both be addressed, and the optimal design of beamforming/precoding will be investigated. Explicit expressions of the achievable outage probability and diversity-multiplexing tradeoff will be developed to demonstrate the performance of the proposed Cooperative secure Transmission schemes, and numerical results are presented.
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linear precoded Cooperative Transmission protocol for wireless broadcast channels
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Chee Yen Leow, Zhiguo Ding, Kin K. LeungAbstract:In multiple-input-single-output (MISO) broadcast channels, the achievable diversity gain is limited by the number of source transmitter antennas. Cooperative Transmission is able to provide another dimension of diversity gain improvement. In this paper, we introduce a spectrally efficient Cooperative Transmission protocol in MISO broadcast channels using linear precoding and nonorthogonal relaying. The proposed protocol can achieve maximum diversity gain expressed as the sum of the number of source transmitter antennas and the number of available relays. The diversity and multiplexing tradeoff of the proposed protocol outperforms the nonCooperative scheme, even when only a single relay is used. For a large number of relay candidates, the diversity and multiplexing tradeoff of the proposed protocol completely surpasses the existing nonCooperative scheme.
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cross layer routing using Cooperative Transmission in vehicular ad hoc networks
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Zhiguo Ding, Kin K. LeungAbstract:Wireless vehicular ad hoc networks are characterized by multi-hop Transmission, where a key problem is the design of routing, e.g., how to efficiently direct the information flow from the source to the destination via available intermediate nodes. In this paper, cross-layer routing is studied by applying Cooperative Transmission and a new strategy of path selection is proposed to achieve a better tradeoff between the Transmission power consumption and end-to-end reliability. The influence of Cooperative Transmission to the wireless link cost is first studied, which shows that the quality of wireless links could be improved significantly. Then we focus on formulating the objective functions for the addressed cross-layer optimization problem. Specifically, according to different quality of service requirements, two different types of routing optimization are investigated to understand the effects of improved link cost to the routing decision. The closed-form expressions of the optimal solutions for two addressed optimization problems are developed and later used as quantitative criteria of the routing decision. Our developed analytical and simulation results show that the criteria using Cooperative Transmission typically yield more efficient routes than the comparable schemes in terms of end-to-end reliability and total Transmission power.
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on the application of Cooperative Transmission to wireless broadcast channels
International Conference on Communications, 2010Co-Authors: Zhiguo Ding, Dennis L. Goeckel, Kin K. Leung, Don TowsleyAbstract:In this paper, we study the application of Cooperative diversity to wireless broadcast channels, a fundamental building block of wireless communication networks. Several Cooperative broadcast protocols will be proposed, and information theoretic metrics are developed to facilitate performance evaluation. Provided that there is no direct S-D link, the proposed protocols can achieve a multiplexing gain close to one, whereas the traditional two-hop scheme can only achieve the diversity gain 1/2. Provided that there are direct S-D links, the proposed protocol can still outperform the comparable scheme, particularly at high multiplexing gains.
Chenyang Yang - One of the best experts on this subject based on the ideXlab platform.
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feedback overhead analysis for base station Cooperative Transmission
IEEE Transactions on Wireless Communications, 2016Co-Authors: Xueying Hou, Chenyang YangAbstract:In this paper, we analyze the feedback overhead of channel direction information for downlink coherent base station (BS) Cooperative Transmission. The per-cell codebooks are considered, which are of practice importance. Instead of analyzing the required number of bits for feedback to keep a constant rate loss, we analyze the required overhead to ensure a target average signal-to-interference-plus-noise ratio (SINR) of each user. To this end, we formulate an optimization problem of bit allocation among the codebooks for local and cross channels that minimizes the total number of bits under the constraint of the average SINR, and find the explicit expression of the solution. We proceed to study the impact of various system parameters and channel features on the overall feedback overhead. Analytical and simulation results reveal that the overhead scales linearly with the overall number of transmit antennas, but decreases with the grow of the cell-edge signal-to-noise ratio. Moreover, the overhead can be significantly reduced by exploiting the diverse performance requirements of the users and the heterogeneous channel features through allocating the number of bits for feedback among multiple users and multiple per-cell links. This provides useful insight for the feedback strategy design of BS cooperation systems.
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downlink base station Cooperative Transmission under limited capacity backhaul
IEEE Transactions on Wireless Communications, 2013Co-Authors: Qian Zhang, Chenyang Yang, Andreas F MolischAbstract:Coordinated multi-point Transmission (CoMP) joint processing (CoMP-JP) is a promising technique for supporting high spectral efficiency in future cellular systems. However, this technique requires high-capacity backhaul links for connecting multiple base stations (BSs), which leads to high deployment costs. CoMP coordinated beamforming (CoMP-CB) needs less backhaul capacity, but with lower maximal multiplexing gain. In this paper, we study downlink CoMP strategies with limited-capacity backhaul. We start by investigating the optimal interference-free Transmission strategy under backhaul rate constraints, where only a part of the data is shared among the BSs. We then study soft and hard switching between the CoMP-JP and CoMP-CB modes. Finally, a closed-form semi-dynamic distributed hard switching scheme is proposed, which depends on the local large-scale channel gains of the users. Simulation results show that both the soft and hard mode switching Transmission perform closely to the optimal strategy and outperform the single-mode CoMP Transmission especially when the backhaul capacity is very limited.
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semi dynamic mode selection in base station Cooperative Transmission system
Vehicular Technology Conference, 2011Co-Authors: Qian Zhang, Chenyang YangAbstract:Base stations (BSs) Cooperative Transmission provides high spectrum efficiency for cellular networks, where the performance gain of each user depends on its location. When training overhead is considered, however, a user jointly served by multiple BSs may even achieve lower net rate than with non-Cooperative Transmission. In this paper, we consider semi-dynamic mode selection for users. We first derive the average rate of each user when it is served under Cooperative or non-Cooperative Transmission. We then propose a closed-form mode selection method where only large-scale fading gains of a user are used. Simulation results validate our analysis and demonstrate a performance gain of the proposed method over both full Cooperative and non-Cooperative Transmission.
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on the energy efficiency of base station sleeping with multicell Cooperative Transmission
Personal Indoor and Mobile Radio Communications, 2011Co-Authors: Shengqian Han, Gang Wang, Chenyang Yang, Ming LeiAbstract:Switching underutilized base stations (BSs) to sleep mode is recognized as a promising approach to reduce energy consumption of cellular networks, but it may increase the transmit power of remaining active BSs to guarantee service coverage. Coordinated multi-point (CoMP) can effectively reduce transmit power of BSs through BS cooperation but requiring extra power consumption due to extra signal processing and backhaul traffic. In this paper, we investigate the energy efficiency of BS sleeping combined with CoMP. A joint power and subcarrier allocation algorithm is proposed to minimize the overall network power consumption with minimum data rate constraints, which can be implemented distributedly across multiple clusters. Simulation results show that BS sleeping combined with CoMP can improve network energy efficiency for high data rate users compared with Non-CoMP systems without BS sleeping.
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how much feedback overhead is required for base station Cooperative Transmission to outperform non Cooperative Transmission
International Conference on Acoustics Speech and Signal Processing, 2011Co-Authors: Xueying Hou, Chenyang YangAbstract:Coherent base station (BS) Cooperative Transmission provides high spectrum efficiency for cellular systems when channel state information (CSI) is perfectly known at the BSs. For frequency division duplexing systems, the CSI is fed back with limited number of bits, which linearly increases with the number of cooperating BSs. In this paper, we study the impact of the quantized CSI on Cooperative Transmission when zero-forcing beamforming is used. By deriving an optimal bit allocation among local and cross channels according to the locations of users, we show the minimal feedback bits required by Cooperative Transmission for providing performance gain over non-Cooperative Transmission.
Osvaldo Simeone - One of the best experts on this subject based on the ideXlab platform.
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coded computing and Cooperative Transmission for wireless distributed matrix multiplication
arXiv: Information Theory, 2021Co-Authors: Meixia Tao, Jingjing Zhang, Osvaldo SimeoneAbstract:Consider a multi-cell mobile edge computing network, in which each user wishes to compute the product of a user-generated data matrix with a network-stored matrix. This is done through task offloading by means of input uploading, distributed computing at edge nodes (ENs), and output downloading. Task offloading may suffer long delay since servers at some ENs may be straggling due to random computation time, and wireless channels may experience severe fading and interference. This paper aims to investigate the interplay among upload, computation, and download latencies during the offloading process in the high signal-to-noise ratio regime from an information-theoretic perspective. A policy based on cascaded coded computing and on coordinated and Cooperative interference management in uplink and downlink is proposed and proved to be approximately optimal for a sufficiently large upload time. By investing more time in uplink Transmission, the policy creates data redundancy at the ENs, which can reduce the computation time, by enabling the use of coded computing, as well as the download time via transmitter cooperation. Moreover, the policy allows computation time to be traded for download time. Numerical examples demonstrate that the proposed policy can improve over existing schemes by significantly reducing the end-to-end execution time.
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fog aided wireless networks for content delivery fundamental latency tradeoffs
IEEE Transactions on Information Theory, 2017Co-Authors: Avik Sengupta, Ravi Tandon, Osvaldo SimeoneAbstract:A fog-aided wireless network architecture is studied in which edge nodes (ENs), such as base stations, are connected to a cloud processor via dedicated fronthaul links while also being endowed with caches. Cloud processing enables the centralized implementation of Cooperative Transmission strategies at the ENs, albeit at the cost of an increased latency due to fronthaul transfer. In contrast, the proactive caching of popular content at the ENs allows for the low-latency delivery of the cached files, but with generally limited opportunities for Cooperative Transmission among the ENs. The interplay between cloud processing and edge caching is addressed from an information-theoretic viewpoint by investigating the fundamental limits of a high signal-to-noise-ratio metric, termed normalized delivery time (NDT), which captures the worst case coding latency for delivering any requested content to the users. The NDT is defined under the assumptions of either serial or pipelined fronthaul-edge Transmission, and is studied as a function of fronthaul and cache capacity constraints. Placement and delivery strategies across both fronthaul and wireless, or edge, segments are proposed with the aim of minimizing the NDT. Information-theoretic lower bounds on the NDT are also derived. Achievability arguments and lower bounds are leveraged to characterize the minimal NDT in a number of important special cases, including systems with no caching capabilities, as well as to prove that the proposed schemes achieve optimality within a constant multiplicative factor of 2 for all values of the problem parameters.