Resource allocations in relay-assisted cellular networks

Abstract

In a relay-assisted cellular network, the transmission mode either direct transmission or relaying and the transmit power of the source and relay nodes affect not only transmission rates of individual links but also the rates of other links sharing the same channel. In this paper, we propose a cross-layer design that jointly considers the transmission mode/relay node selection MRS with power allocation PA to optimize the system rate. We first formulate an optimization problem for a cellular system, where the same frequency channel can be reused in different cells. A low complexity heuristic MRS scheme is proposed on the basis of the link and interference conditions of the source and potential relay nodes. Given the transmission mode and relay node if the relaying mode is chosen of each link, the transmit power of the source and relay nodes can be solved by geometric programming. This method for MRS and PA can achieve a close-to-optimum performance, but implementing the PA requires heavy signalling exchanged among cells. To reduce the signalling overheads, we finally proposed a heuristic and distributed method for MRS and PA inspired by some asymptotic analysis. Numerical results are conducted to demonstrate the rate performance of the proposed methods.Copyright ©2013 John Wiley & Sons, Ltd.