Co-ordinate Interleaved Distributed Space-Time Coding for Two-Antenna-Relays Networks

TL;DR

This paper introduces Co-ordinate Interleaved Distributed Space-Time Codes (CIDSTC) for two-antenna relay networks, enhancing diversity and coding gain with minimal complexity increase compared to previous schemes.

Contribution

The paper proposes a novel CIDSTC scheme that interleaves in-phase and quadrature components at relays, improving diversity and coding gain over existing methods.

Findings

CIDSTC achieves the same asymptotic diversity order as previous schemes.

CIDSTC provides higher diversity for moderate and large power levels.

The scheme is fully diverse with appropriate multi-dimensional signal sets.

Abstract

Distributed space time coding for wireless relay networks when the source, the destination and the relays have multiple antennas have been studied by Jing and Hassibi. In this set-up, the transmit and the receive signals at different antennas of the same relay are processed and designed independently, even though the antennas are colocated. In this paper, a wireless relay network with single antenna at the source and the destination and two antennas at each of the R relays is considered. A new class of distributed space time block codes called Co-ordinate Interleaved Distributed Space-Time Codes (CIDSTC) are introduced where, in the first phase, the source transmits a T-length complex vector to all the relays and in the second phase, at each relay, the in-phase and quadrature component vectors of the received complex vectors at the two antennas are interleaved and processed before forwarding them to the destination. Compared to the scheme proposed by Jing-Hassibi, for $T \geq 4R$, while providing the same asymptotic diversity order of 2R, CIDSTC scheme is shown to provide asymptotic coding gain with the cost of negligible increase in the processing complexity at the relays. However, for moderate and large values of P, CIDSTC scheme is shown to provide more diversity than that of the scheme proposed by Jing-Hassibi. CIDSTCs are shown to be fully diverse provided the information symbols take value from an appropriate multi-dimensional signal set.