Differential Distributed Space-Time Coding with Imperfect Synchronization in Frequency-Selective Channels

TL;DR

This paper introduces a differential distributed space-time coding scheme for relay networks operating over frequency-selective channels with synchronization errors, effectively mitigating ISI and maintaining high diversity without channel state information.

Contribution

It proposes a novel differential encoding and decoding method that handles ISI and synchronization errors in frequency-selective fading channels, achieving maximum diversity with low complexity.

Findings

The method effectively mitigates ISI in frequency-selective channels.

It maintains robustness against synchronization errors.

Simulation results confirm improved performance in various scenarios.

Abstract

Differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed that channels are flat-fading and relays are perfectly synchronized at the symbol level. However, due to the delay spread in broadband systems and the distributed nature of relay networks, these assumptions may be violated. Hence, inter-symbol interference (ISI) may appear. This paper proposes a new differential encoding and decoding process for D-DSTC systems with multiple relays over slow frequency-selective fading channels with imperfect synchronization. The proposed method overcomes the ISI caused by frequency-selectivity and is robust against synchronization errors while not requiring any channel information at the relays and destination. Moreover, the maximum possible diversity with a decoding complexity similar to that of the conventional D-DSTC is attained. Simulation results are provided to show the performance of the proposed method in various scenarios.