On the performance of cooperative diversity protocols in practical wireless systems

The concepts of cooperative diversity promise to offer the benefits of spatial diversity gains to handheld wireless devices with single antennas. The information-theoretic bounds that have been established recently serve as basic guidelines; yet, the performance of such protocols should additionally be examined for more realistic assumptions. Towards this end, we study cooperative diversity protocols for systems employing limited modulation alphabets and realistic receiver structures regarding the knowledge of channel state information. Our findings imply that under these conditions full second order diversity can only be achieved by using adaptive versions of cooperative protocols. As with other diversity schemes (e.g. space time block codes), our results for uncoded transmission can easily be combined with FEC techniques to obtain excellent error rate performance.