Coded Cooperation in Wireless Communications: Space-Time Transmission and Iterative Decoding

TLDR

Conventional space‑time coding cannot provide uplink diversity for single‑antenna mobiles, so cooperation diversity was introduced and coded cooperation emerged as a powerful variant. This work proposes two extensions to coded cooperation: enhancing diversity in fast fading by incorporating space‑time code concepts and integrating turbo coding into the dual‑component framework. Coded cooperation partitions each mobile’s codeword and transmits segments over independent fading channels, while the extensions employ space‑time code techniques for diversity and turbo codes for error correction, with analytical bounds derived for both. Theoretical bounds and simulations show that both extensions yield significant error‑rate improvements over the baseline coded cooperation.

Abstract

When mobiles cannot support multiple antennas due to size or other constraints, conventional space-time coding cannot be used to provide uplink transmit diversity. To address this limitation, the concept of cooperation diversity has been introduced, where mobiles achieve uplink transmit diversity by relaying each other's messages. A particularly powerful variation of this principle is coded cooperation. Instead of a simple repetition relay, coded cooperation partitions the codewords of each mobile and transmits portions of each codeword through independent fading channels. This paper presents two extensions to the coded cooperation framework. First, we increase the diversity of coded cooperation in the fast-fading scenario via ideas borrowed from space-time codes. We calculate bounds for the bit- and block-error rates to demonstrate the resulting gains. Second, since cooperative coding contains two code components, it is natural to apply turbo codes to this framework. We investigate the application of turbo codes in coded cooperation and demonstrate the resulting gains via error bounds and simulations.