A novel error detection due to joint CRC aided denoise-and-forward network coding for two-way relay channels.

Yulun Cheng,Longxiang Yang

doi:10.1155/2014/470324

Abstract

In wireless two-way (TW) relay channels, denoise-and-forward (DNF) network coding (NC) is a promising technique to achieve spectral efficiency. However, unsuccessful detection at relay severely deteriorates the diversity gain, as well as end-to-end pairwise error probability (PEP). To handle this issue, a novel joint cyclic redundancy code (CRC) check method (JCRC) is proposed in this paper by exploiting the property of two NC combined CRC codewords. Firstly, the detection probability bounds of the proposed method are derived to prove its efficiency in evaluating the reliability of NC signals. On the basis of that, three JCRC aided TW DNF NC schemes are proposed, and the corresponding PEP performances are also derived. Numerical results reveal that JCRC aided TW DNF NC has similar PEP comparing with the separate CRC one, while the complexity is reduced to half. Besides, it demonstrates that the proposed schemes outperform the conventional one with log-likelihood ratio threshold.

Highlights

The capacity bounds of two-way (TW) communication channel were first studied and calculated in the 1960s [1], various cooperative strategies have been extended to transmit over TW relay channels [2,3,4,5,6] only since the advent of network coding (NC) [7, 8] in recent years
The results show that 2T JCRC-PA is superior to likelihood ratio- (LLR-)based check in all SNR regions, which indicates that 2T JCRC-PA is able to fully exploit the relay channel to improve pairwise error probability (PEP) performance
We introduced JCRC check into the TW DNF NC system to evaluate the reliability of NC signals

Summary

Introduction

The capacity bounds of two-way (TW) communication channel were first studied and calculated in the 1960s [1], various cooperative strategies have been extended to transmit over TW relay channels [2,3,4,5,6] only since the advent of network coding (NC) [7, 8] in recent years. TW NC is consisted of multiaccess (MA) and broadcasting (BC) phases, and in the existing literatures, there are three main NC schemes that were studied in MA phase, which are XOR NC [8], amplify-and-forward (ANF) NC [9], and denoiseand-forward (DNF) NC [10] Among these schemes, DNF is one of the most promising ones due to its very high spectral efficiency, since the TW communication can be accomplished within 2 time slots (TS), while 3 TS are required for XOR NC and ANF NC. In [12], this type of threshold is introduced into TW NC to evaluate the reliability of network coded bits, named as NC bit threshold Besides these uncoded methods, [16, 17] employ cyclic redundancy code (CRC) check at relay for error bit identification.

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Conclusion