Bilayer protograph codes for half-duplex relay channels

Abstract

Despite encouraging advances in the design of relay codes, several important challenges remain.Many of the existing LDPC relay codes are tightly optimized for fixed channel conditions and not easily adapted without extensive re-optimization of the code. Some have high encoding complexity and some need long block lengths to approach capacity. This paper presents a high-performance protograph-based LDPC coding scheme for the half-duplex relay channel that addresses simultaneously several important issues: structured coding that permits easy design, low encoding complexity, embedded structure for convenient adaptation to various channel conditions, and performance close to capacity with a reasonable block length. The application of the coding structure to multi-relay networks is demonstrated. Finally, a simple new methodology for evaluating the end-to-end error performance of relay coding systems is developed and used to highlight the performance of the proposed codes.

A Survey on Protograph LDPC Codes and Their Applications

“…The relay channel [129], which is the most elementary framework of cooperative communication systems, has attracted much attention in recent years. Inspired by the work of [130], bilayer protograph codes have been designed for the three-node half-duplex relay systems with decode-and-forward (DF) protocol so as to remarkably improve the error performance [101], [102]. Similar to the design of RCP codes, the capacity-approaching bilayer protograph codes can also be constructed via either expurgating (adding new rows, i.e., CNs, into a base matrix) or lengthening (adding new columns, i.e., VNs, into a base matrix).…”

“…Similar to the design of RCP codes, the capacity-approaching bilayer protograph codes can also be constructed via either expurgating (adding new rows, i.e., CNs, into a base matrix) or lengthening (adding new columns, i.e., VNs, into a base matrix). Here, we just elaborate a little further on the construction of bilayer lengthened protograph codes, while the design of bilayer expurgated protograph codes can be found in [101], [102].…”

“…Using the redundancy, V RD can be correctly retrieved at D. As a result, the sub-protograph in layer-2 can be removed from the whole protograph and the remaining decoding is only performed on C SD . One can refer to [101], [102], [130] for more comprehensive knowledge of bilayer coding framework.…”

“…The unequal-diversity protograph code, which is considered as a type of bilayer protograph codes [101], [102], can be constructed by concatenating two IRA/RA codes. As observed, the authors in [112] have designed several rate-7/10 unequal-diversity protograph codes.…”

Spatially Coupled Protograph-Based LDPC Codes for Decode-and-Forward in Erasure Relay Channel

“…N R . Design of LDPC codes for relay channels with DF strategy was discussed in several papers [14], [15], [16], [17]. The sender S sends a codeword x encoded by an LDPC code.…”