The Impact of CSI and Power Allocation on Relay Channel Capacity and Cooperation Strategies.pdfVIP

The Impact of CSI and Power Allocation on Relay Channel Capacity and Cooperation Strategies Chris T. K. Ng, Student Member, IEEE, Andrea J. Goldsmith, Fellow, IEEE 7 0 0 2 Abstract n a J Capacity gain from transmitter and receiver cooperation are compared in a relay network where the 8 cooperating nodes are close together. Under quasi-static channels, when all nodes have equal average 1 transmit power along with full channel state information (CSI), it is shown that transmitter cooperation 1 v outperforms receiver cooperation, whereas the opposite is true when power is optimally allocated among 6 the cooperating nodes but only CSI at the receiver (CSIR) is available. When the nodes have equal power 1 1 with CSIR only, cooperative schemes are shown to offer no capacity improvement over non-cooperation 1 0 under the same network power constraint. When the system is under optimal power allocation with full 7 0 CSI, the decode-and-forward transmitter cooperation rate is close to its cut-set capacity upper bound, / T and outperforms compress-and-forward receiver cooperation. Under Rayleigh fading in the high SNR I . regime, similar conclusions follow. Cooperative systems provide resilience to channel fading; however, s c capacity becomes more sensitive to power allocation, and the cooperating nodes need to be closer : v i together for the decode-and-forward scheme to be capacity-achieving. Moreover, to realize capacity X r improvement, full CSI is necessary in transmitter cooperation, while in receiver co