A Distributed Space-Time Trellis Coding Approach for Multi-Terminal Relay Networks

Cooperative relaying is a promising alternative for conventional mobile communications systems as it is able to increase coverage and throughput of these systems. Due to practical constraints most cooperative relaying protocols employ half-duplex relays which implies the need for an increased data rate on the individual links and causes a significant performance loss at higher rates. This paper presents a novel cooperative relaying approach exploiting existing large scale space diversity as well as an additional coding gain by employing a spatial duplex approach. The scheme utilizes a network of alternatingly sending and receiving relay terminals where only one relay node is transmitting at a particular time. This spatial duplexing approach is used to implement a distributed Space-Time Trellis Code (STTC) for virtual antenna arrays. In this work, the protocol is applied to a convolutionally coded system. Due to the serial concatenation of an inner STTC and an outer convolutional code, the destination is able to use well-known turbo-decoding algorithms to reduce the frame error rate of the system. The assessment of the approach is done by comparing it with conventional relaying, a time/frequency duplex cooperative relaying protocol and direct transmission.