High Rate Single-Symbol ML Decodable Precoded DSTBCs for Cooperative Networks

TL;DR

This paper introduces Semi-orthogonal Precoded Distributed Single-Symbol Decodable STBCs (S-PDSSDCs) for cooperative networks, which improve upon DOSTBCs in rate and error performance by using coordinate interleaving at the source.

Contribution

The paper presents a new class of distributed space-time block codes, S-PDSSDCs, with higher rates and systematic construction methods, extending the capabilities of existing DOSTBCs.

Findings

S-PDSSDCs achieve approximately twice the rate of DOSTBCs.

Constructed codes attain the upper bound on rate for certain relay configurations.

Simulation shows S-PDSSDCs outperform DOSTBCs in error probability.

Abstract

Distributed Orthogonal Space-Time Block Codes (DOSTBCs) achieving full diversity order and single-symbol ML decodability have been introduced recently by Yi and Kim for cooperative networks and an upperbound on the maximal rate of such codes along with code constructions has been presented. In this paper, we introduce a new class of Distributed STBCs called Semi-orthogonal Precoded Distributed Single-Symbol Decodable STBCs (S-PDSSDC) wherein, the source performs co-ordinate interleaving of information symbols appropriately before transmitting it to all the relays. It is shown that DOSTBCs are a special case of S-PDSSDCs. A special class of S-PDSSDCs having diagonal covariance matrix at the destination is studied and an upperbound on the maximal rate of such codes is derived. The bounds obtained are approximately twice larger than that of the DOSTBCs. A systematic construction of S-PDSSDCs is presented when the number of relays $K \geq 4$. The constructed codes are shown to achieve the upperbound on the rate when $K$ is of the form 0 or 3 modulo 4. For the rest of the values of $K$, the constructed codes are shown to have rates higher than that of DOSTBCs. It is shown that S-PDSSDCs cannot be constructed with any form of linear processing at the relays when the source doesn't perform co-ordinate interleaving of the information symbols. Simulation result shows that S-PDSSDCs have better probability of error performance than that of DOSTBCs.