Symbol error probabilities for general cooperative links

Cooperative diversity (CD) networks have been receiving a lot of attention recently as a distributed means of improving error performance and capacity. This paper derives the average symbol error probability (SEP) for amplify and forward CD links. The resulting expressions are general as they hold for an arbitrary number of cooperating branches, arbitrary number of cooperating hops per branch, and many channel fading models. Their simplicity provides valuable insights to the performance of CD networks and allows their optimization. Besides revealing the diversity advantage, they clearly show from where this advantage comes from and prove that the diversity advantage holds independently of the channel fading model. Finally, explain how diversity is improved in multihop CD networks.