Deakin University
Browse

File(s) under permanent embargo

On the energy efficiency of a relaying protocol with HARQ-IR and distributed cooperative beamforming

journal contribution
posted on 2013-02-01, 00:00 authored by Jinho ChoiJinho Choi, W Xing, D To, Y Wu, S Xu
Hybrid automatic repeat request (HARQ) protocols can be employed for reliable transmissions of delay tolerant traffics over fading channels. Relay-aided transmissions can offer various advantages over direct transmissions in wireless communications including transmission power saving. In this paper, we consider the energy efficiency of a relaying protocol that is based on the HARQ protocol with incremental redundancy (HARQ-IR) when distributed cooperative beamforming (DCB) is employed in a wireless relay system. It is assumed that multiple relays between a source node (SN) and a destination node (DN) are available for relaying and some of them are selected for DCB. In the proposed relaying protocol, the signal transmission consists of two phases and each phase can have an independent HARQ-IR protocol. It is shown in this paper that although the performance can be improved when the number of selected relays for DCB increases as the diversity gain increases, it is not true in terms of the energy efficiency. For Rayleigh fading channels, closed-form expressions are derived for the average numbers of transmissions for each phase. From them, under a certain energy efficiency criterion, we can find the optimal number of multiple selected relays for DCB to forward signals from relays to DN. © 2012 IEEE.

History

Journal

IEEE transactions on wireless communications

Volume

12

Issue

2

Pagination

769 - 781

Publisher

IEEE

Location

Piscataway, N.J.

ISSN

1536-1276

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2013, IEEE