-
[show abstract]
[hide abstract]
ABSTRACT: This paper investigates the Resource allocation problem in OFDMA-based decode-and-forward cooperative communication systems.
The objective is to maximize the sum throughput under the constraints of joint total transmission power and subchannels occupation,
while maintaining the maximum fairness among multiple relay nodes. Since the optimal solution to this combinatorial problem
is extremely computationally complex to obtain, we propose a low-complexity suboptimal algorithm that allocates subchannel
and power separately. In the proposed algorithm, subchannel allocation over the relay nodes is first performed under the assumption
of equal power distribution. Then, an optimal power allocation algorithm named multi-level water-filling is used to maximize
the sum rate. The simulation results show that the performance of the proposed algorithm can approach asymptotically to that
of the optimal algorithm while enhancing the fairness among all relay nodes and reducing computational complexity from exponential
to linear with the number of subchannels. It is also shown that the proposed equal power distribution algorithm with subchannel
permutation (SP) outperforms the one without SP.
KeywordsCooperative communication–OFDMA–Resource allocation–Fairness
Wireless Personal Communications 04/2012; 62(3):655-670. · 0.46 Impact Factor
-
Proceedings of the Global Communications Conference, GLOBECOM 2011, 5-9 December 2011, Houston, Texas, USA; 01/2011
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we consider a dual-hop multiple-input-multiple-output (MIMO) relay wireless network, in which a source-destination pair, which are both equipped with multiple antennas, communicates through a large number of half-duplex amplify-and-forward (AF) relay terminals. Two novel linear beamforming schemes based on the matched filter and regularized zero-forcing precoding techniques are proposed for the MIMO relay system. We focus on the linear process at the relay nodes and design the new relay beamformers by utilizing the channel-state information (CSI) of both backward and forward channels. The proposed beamforming designs are based on the QR decomposition filter at the destination node, which performs successive interference cancellation to achieve the maximum spatial-multiplexing gain. Simulation results demonstrate that the proposed beamformers that fulfil both the intranode array gain and distributed array gain outperform other relaying schemes under different system parameters in terms of the ergodic capacity.
IEEE Transactions on Vehicular Technology 11/2010; · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a novel antenna selection algorithm for amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay networks. Assuming equal-power allocation across the activated antennas, we iteratively select the antenna pairs to greedily maximize the network capacity in closed-form expressions. Simulation results show that our algorithm greatly outperforms the existing schemes, with the gain being more pronounced when the noise at relay nodes is relatively high. Moreover, from the results, we propose a conjecture that the network capacity with antenna selection shall scale logographically with respect to the number of relays, which achieves the capacity upper bound in the sense of asymptotic capacity scaling tendency.
Communications (ICC), 2010 IEEE International Conference on; 06/2010
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a greedy minimum mean squared error (MMSE)-based antenna selection algorithm for amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay systems. Assuming equal-power allocation across the multi-stream data, we derive a closed form expression for the mean squared error (MSE) resulted from adding each additional antenna pair. Based on this result, we iteratively select the antenna-pairs at the relay nodes to minimize the MSE. Simulation results show that our algorithm greatly outperforms the existing schemes.
IEEE Signal Processing Letters 06/2010; · 1.39 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper deals with the design and analysis of low complexity user scheduling algorithm in multiantenna broadcast (downlink) systems under zero-forcing multiplexing. By using quantization technology, the channel matrix can be divided into serval unoverlapped channel regions. Based on the quantized channel regions, we can get semi-orthogonal region sets. The presented user scheduling algorithm in this paper is based on using the semi-orthogonal region sets. Simulation results shows that this algorithm can achieve a sum rate close to the full searching algorithms while with much lower complexity than those of the previous algorithms.
Communications and Networking in China, 2009. ChinaCOM 2009. Fourth International Conference on; 09/2009
-
[show abstract]
[hide abstract]
ABSTRACT: This paper investigates the resource allocation problem in the downlink of OFDMA cooperative relaying networks with one source (base station) and multiple relay and destination nodes. Assuming that the base station knows all the instantaneous channel gains of all links, we propose a dynamic joint subchannel and power allocation (SPA) scheme whose objective is to maximize the worst user's data rate with the constraint of total transmission power. Since the optimal solution to this combinatorial problem is extremely computationally complex, we propose a low-complexity suboptimal algorithm that allocates subchannel and power separately. In the proposed algorithm, subchannels are firstly paired by relay nodes according to their equivalent channel gains and then assigned to a specific user. Subsequently, an optimal power distribution algorithm is designed for the proposed subchannel allocation (SA) scheme. The simulation results show that the performance of the proposed algorithm approaches asymptotically to that of the optimal one, and maximal fairness is guaranteed for all users.
Communications, 2009. ICC '09. IEEE International Conference on; 07/2009
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we consider the dynamic subchannel allocation problem in OFDMA-based selective relaying networks. Our goal is to maximize the total throughput under the constraint of total transmission power, while guaranteeing fairness on subchannel occupation by multiple destination nodes (users). Since the optimal solution to this optimization problem is extremely computationally complex to obtain, we decompose the original optimization problem into two subproblems. Firstly, we assign subchannels to the users with the best equivalent channel gains for them under the assumption of equal power distribution among all subchannels. Secondly, water-filling method is adopted to distribute the power to the determined links. Simulation results show that the performance of the proposed algorithm approaches asymptotically to that of the optimal one, while reducing computational complexity from exponential to linear with the numbers of subchannels, relay nodes and users. It is also shown that subchannel permutation (SP) scheme brings additional throughput gain to DF cooperative transmission.
Wireless Communications and Networking Conference, 2009. WCNC 2009. IEEE; 05/2009
-
IEICE Transactions. 01/2009; 92-B:1397-1400.
-
IEICE Transactions. 01/2009; 92-B:1822-1824.
-
Int. J. Communication Systems. 01/2009; 22:1593-1607.
-
Proceedings of IEEE International Conference on Communications, ICC 2009, Dresden, Germany, 14-18 June 2009; 01/2009
-
[show abstract]
[hide abstract]
ABSTRACT: In this letter, we address the problem of transceiver design in a non-regenerative MIMO relay system, where linear processing is applied at both the relay and destination to jointly minimize the mean-squared error (MSE) of symbol estimations. Under average power constraint at the relay station, we show that the optimal relay-precoder always loads power across channel eigenvectors and then decomposes the equivalent MIMO channel into a set of parallel SISO channels. Simulation results demonstrate that our method outperforms other relaying schemes in terms of both BER and MSE.
IEEE Communications Letters 08/2008; · 0.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The decision-directed space-alternating generalized expectation-maximization (SAGE) algorithm is introduced in [1] to estimate the channel and track the channel varying for OFDM systems with transmitter diversity. However, this method is based upon a discrete Fourier transform (DFT), which will cause power leakage and result in an error floor in a multipath channel with non-sample-spaced time delays. In order to overcome this problem, a low rank approximation method is presented by using the signal subspace of the channel frequency autocorrelation matrix. Furthermore, a modified fast subspace tracking algorithm is introduced to adaptive estimate the signal subspace by using a space–time block coded training blocks sent at regular interval. Simulation results show the advantages of the proposed technique for MIMO-OFDM systems in time-varying non-sample-spaced wireless channels.
Image and Signal Processing, 2008. CISP '08. Congress on; 06/2008
-
[show abstract]
[hide abstract]
ABSTRACT: This paper deals with the design and analysis of low complexity user scheduling algorithm in multi-antenna broadcast (downlink) systems under zero-forcing multiplexing with limited feedback. By using quantization technology, the channel matrix can be divided into several unoverlapped channel regions. Based on the quantized channel regions, we can get semi-orthogonal region sets. Then the transmitter can carry out user scheduling by using the feedback channel direction information (CDI), channel quality information (CQI) and the quantized semi-orthogonal channel region sets. Simulation results show that the presented user scheduling algorithm can achieve a sum rate close to the full searching algorithms while with much lower complexity than those of the previous algorithms.
Circuits and Systems for Communications, 2008. ICCSC 2008. 4th IEEE International Conference on; 06/2008
-
[show abstract]
[hide abstract]
ABSTRACT: This paper studies the problem of queue control and user scheduling in multi-antenna broadcast (downlink) systems under zero forcing beamforming (ZFBF) transmit strategy. In the system, we assume that the data packet arrives randomly to the buffered transmitter. By taking the broadcast channel as a controlled queueing system, we deduce the property of queue control function which maximizes the weighted system throughput while guarantees the delay fairness among users. We also present a low complexity user selection algorithm with the consideration of queue state and channel state together. Simulation results show that the joint queue control and user selection policy can achieve considerable fairness and stability among users.
Communications, 2008. ICC '08. IEEE International Conference on; 06/2008
-
[show abstract]
[hide abstract]
ABSTRACT: In this letter, we address the problem of fulfilling quality-of-service (QoS) requirements in a multiple-input multiple-output (MIMO) relay system, where a set of target signal-to-noise ratios (SNRs) should be attained on different substreams. By solving a two-step optimization problem, we obtain a power-efficient relaying scheme that can make the SNR requirements asymptotically fulfilled. A simple relay selection method is also proposed such that the relay-power consumption can be largely reduced when there is a large number of relays.
IEEE Signal Processing Letters 02/2008; · 1.39 Impact Factor
-
IEICE Transactions. 01/2008; 91-B:2049-2052.
-
IEEE Transactions on Wireless Communications. 01/2007; 6:1046-1055.
-
IEICE Transactions. 01/2007; 90-B:388-391.
