Opportunistic Joint Decoding with Scheduling and Power Allocation in OFDMA Femtocell Networks

One of the major challenges in deploying femtocells is the management of interference between neighboring femtocells and between the femtocells and the macrocells. This paper explores the use of opportunistic multiuser detection for interference mitigation in the downlink of an orthogonal frequency division multiple access (OFDMA) femtocell network. In particular, we focus on the use of joint decoding (JD) at the receiver, where a macro or femto user may jointly decode both the desired message and the message from a selected interfering user in order to achieve a higher overall transmission rate. It is shown that to take the full advantage of opportunistic multiuser detection, the selection of JD pairs needs to be jointly optimized with scheduling, power allocation, and rate adaptation. This paper adopts a network utility maximization framework and proposes an iterative algorithm for such a joint optimization across the network. Simulation results show that multiuser detection can significantly benefit the femto-users, while maintaining the performance of macro-users. Further, although the lower-complexity successive interference cancellation (SIC) scheme can already reap significant benefit of multiuser detection, JD can further improve upon SIC.