Cooperative relaying scheme with space time code for multihop communications among single antenna terminals

In mobile multihop communications, the diversity technique is important since the channel between mobile terminals may suffer from the effects of fading and the routes between terminals are normally created through several hops. Space-time coding using multiple transmit antennas is an effective countermeasure for fading. For terminals which have only one antenna, due to the size/cost limitations, user cooperation has been introduced as a diversity technique. In this paper, a space-time coded cooperative relaying scheme for a multihop communications scenario, in cases where the number of hops is more than two, is proposed in order to combat the effects of fading among single antenna terminals, without bandwidth expansion. The scheme utilizes a space-time code for cooperative relaying and is developed in both frequency-flat and frequency-selective fading channels. By computer simulations, it is shown that the proposed scheme provides diversity gain and more improvement of frame error rate as the number of hops increases. Furthermore, the effects of an error correcting code and co-channel interference are shown.