Linear Processing Design of Amplify-and-Forward Relays for Maximizing the System Throughput

Qiang Wang,Tiejun Chen,Tingting Lan

doi:10.1155/2018/5676215

Qiang Wang, Tiejun Chen + Show 1 more

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https://doi.org/10.1155/2018/5676215

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Abstract

In this paper, firstly, we study the linear processing of amplify-and-forward (AF) relays for the multiple relays multiple users scenario. We regard all relays as one special “relay”, and then the subcarrier pairing, relay selection and channel assignment can be seen as a linear processing of the special “relay”. Under fixed power allocation, the linear processing of AF relays can be regarded as a permutation matrix. Employing the partitioned matrix, we propose an optimal linear processing design for AF relays to find the optimal permutation matrix based on the sorting of the received SNR over the subcarriers from BS to relays and from relays to users, respectively. Then, we prove the optimality of the proposed linear processing scheme. Through the proposed linear processing scheme, we can obtain the optimal subcarrier paring, relay selection and channel assignment under given power allocation in polynomial time. Finally, we propose an iterative algorithm based on the proposed linear processing scheme and Lagrange dual domain method to jointly optimize the joint optimization problem involving the subcarrier paring, relay selection, channel assignment and power allocation. Simulation results illustrate that the proposed algorithm can achieve a perfect performance.

Highlights

Relay-assisted cooperative communication and orthogonal frequency-division multiplexing (OFDM) are core technologies for the generation mobile communication system which attract tremendous attentions
We propose a linear processing scheme for the AF relays under fixed power allocation which can find out the optimal permutation matrix, and we prove the optimality of this linear processing design
Our goal is to investigate what form of the linear processing scheme leads to the optimal relay selection and subcarrier pairing

Summary

Introduction

Relay-assisted cooperative communication and orthogonal frequency-division multiplexing (OFDM) are core technologies for the generation mobile communication system which attract tremendous attentions. Relay-assist cooperative communication can effectively extend communication coverage, and reduce the consumption of transmit power. It can improve overall system throughput due to its exploiting spatial diversity and combating channel fading [1, 2]. OFDM divides a wideband channel into some orthogonal narrow band subcarriers. The fast data flow can be transformed to a set of slow data flows. OFDM can increase the flexibility for coding and modulation. Relay-assisted cooperative communication and OFDM are adopted by a lot of communication standards, such as 3GPP and IEEE 802.16e

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