Interference Mitigation through Successive Cancellation in Heterogeneous Networks

We present a practical interference management scheme for heterogeneous networks (HetNets). The underlying ideas are based on (i) Han-Kobayashi-type message splitting (MS) where the receivers decode and cancel “part” of the interference which is accordingly optimized by the transmitters to ensure decoding and (ii) opportunistic interference cancellation (OIC) where the interfering transmitters act independently of the receivers that employ interference cancellation. We develop a novel transmission and reception scheme, called joint MS and OIC (MS-OIC), that engages both MS and OIC to account for a practical HetNet system with multiple macrocells and femtocells. The MS component includes a precoder design that judiciously maximizes the weighted sum throughput via the enabling of interference cancellation. A system design along with a novel scheduler that facilitates MS-OIC in a general HetNet system is also developed. System level simulations for a general HetNet system are presented, and the proposed MS-OIC scheme is compared with benchmark schemes such as Coordinated Beamforming (CBF) and joint CBF and Almost Blank Subframes (CBF-ABS). It is observed that the proposed MS-OIC scheme improves the macrocell throughput substantially, balances the achievable rates between the macrocell and femtocell users, and provides significant outage performance improvement in the system. 1. Introduction The steady march of Moore’s law has brought an ever-increasing level of processing power not only to desktop and laptop computers but also to mobile devices. The users of these devices have come to expect broadband performance from their cellular networks to match their device capabilities, and for the most part, network capacity has grown commensurately. The resultant explosive growth in network capacity has been consistent with Cooper’s Law [1] which observes that network capacity (e.g., total data delivery per month) has been doubling every 30 months since the days of Marconi and is predicted to continue for the foreseeable future. A breakdown of Cooper’s law [1] reveals that the vast majority of network capacity comes from denser deployments, specifically, adding more cells. The practicality of this approach for macro deployments is now becoming questionable. Operators wish to make the most of their existing grid of macro sites and are looking towards pico- and femtocells to address increased data demand, particularly in hotspot regions. The resulting mix of macro/femtocells, called a heterogeneous network (HetNet), can in principle provide cost-effective data