Adaptive power adjusting for space-time coding based on two-transmitter and two-receiver cooperation

Abstract

The single antenna user nodes at the transmitters and at the receivers share their antennas to form a virtual multiple antenna system and to realize the cooperative diversity. It can enlarge the systempsilas capacity and enhance the service quality of the ad hoc network and improve the systempsilas performance. Applying the orthogonal property of the space-time coding, we transform the vector signal jointly maximum likelihood (ML) decoding into single symbol decoding, and we provide the single symbol decoding methods for the situations in decode and forward mode (DF) and in amplify and forward (AF) separately. After smoothing the noisepsilas influence, we can enhance the systempsilas performance. Given the total power at the transmitter, adaptively adjust the target signal power and the cooperative signal power according to the channel quality information, the performance in AF mode approaches that of DF mode. Simulation demonstrates that the application of userpsilas cooperation diversity can effetely improve the systempsilas performance. If the channel quality information is known at the transmitter, we can adaptively adjust the target signalpsilas transmit power and the cooperative signalpsilas transmit power to get much more performance improvement. Otherwise space-time coding in AF mode is a better choice instead of that in DF mode.