Performance of variable time-fraction collaborative communication

The diversity advantage of MIMO systems has recently been exploited in collaborative schemes. This allows the nodes without access to multiple transmitting antenna elements to transmit information more efficiently. In a previous work, the authors proposed the collaborative scheme using a variable time fraction. In this paper, this scheme is further studied and an upper bound on the performance of the variable time fraction collaborative protocol is provided. In order to obtain the performance, a new pairwise error probability (PEP) taking into account the location of the transmitting nodes is derived. A new method to analyze layered codes in general is also obtained. The derived upper bound is further used to show the advantages of using a variable time fraction.