2 research outputs found
An Efficient Adaptive Distributed Space-Time Coding Scheme for Cooperative Relaying
A non-regenerative dual-hop wireless system based on a distributed space-time
coding strategy is considered. It is assumed that each relay retransmits an
appropriately scaled space-time coded version of its received signal. The main
goal of this paper is to investigate a power allocation strategy in relay
stations, which is based on minimizing the outage probability. In the high
signal-to-noise ratio regime for the relay-destination link, it is shown that a
threshold-based power allocation scheme (i.e., the relay remains silent if its
channel gain with the source is less than a prespecified threshold) is optimum.
Monte-Carlo simulations show that the derived on-off power allocation scheme
performs close to optimum for finite signal-to-noise ratio values. Numerical
results demonstrate a dramatic improvement in system performance as compared to
the case that the relay stations forward their received signals with full
power. In addition, a hybrid amplify-and-forward/detect-and-forward scheme is
proposed for the case that the quality of the source-relay link is good.
Finally, the robustness of the proposed scheme in the presence of channel
estimation errors is numerically evaluated.Comment: submitted to IEEE Transactions on Wireless Communications (24 pages
On the performance of distributed space-time block coding over nonidentical Ricean channels and the optimum power allocation
10.1109/ICC.2007.927IEEE International Conference on Communications5592-559