Effective Capacity of Multisource Multidestination Cooperative Systems Under Cochannel Interference

Abstract

We introduce a novel analytical framework for the end-to-end (e2e) maximum throughput under delay constraints, namely effective capacity (EC), for multisource and multidestination amplify-and-forward cooperative networks. The network operates in the presence of Rayleigh fading and employs frequency-division duplex nodes having the ability to simultaneously transmit as sources and receive as relays. Cochannel interference and noise are present at the relay nodes, whereas the destination nodes are noise limited. A linear precoding technique is applied during reception to combine the input signals. As precoding, zero forcing (ZF), maximal-ratio combining (MRC), and minimum mean-squared error (MMSE) are studied. Each relay forwards the received signal to the destination by employing the maximum-ratio transmission (MRT) scheme. Both exact analytical expressions and tight high signal-to-noise ratio bounds of e2e EC are obtained for the ZF/MRT scheme while the optimal power allocation problem maximizing the e2e EC is also addressed. For the MRC/MRT and MMSE/MRT schemes, we derive approximate, yet highly accurate EC analytical expressions, as well as asymptotically tight closed-form expressions. Selected numerical and simulation results show that MMSE/MRT always yields the best performance followed by the ZF/MRT and MRC/MRT schemes. Moreover, it is shown that as the number of relay nodes increases, the ZF/MRT and MMSE/MRT schemes achieve almost identical and always better e2e EC performance than the MRC/MRT one.