Macro-Pico Amplitude-Space Sharing with Optimized Han-Kobayashi Coding

Heterogeneous network is a new paradigm in next generation cellular systems, which is promised to significantly improve the spatial spectrum efficiency through overlapped coverage. This however calls for efficient interference management techniques. In this paper, we propose an amplitude-space sharing strategy among the macro-cell user and pico-cell users, where different users occupy different levels in the signal amplitude-space. By optimizing the space sharing scheme, different layers of signal and interference are separable at each receiver and the network sum-rate can be maximized. We start from the single pico-cell scenario, where we employ Han-Kobayashi coding and derive the optimal transmit powers allocated to the private and common information of the users. With a unified framework, we derive the achievable sum-rates for various interference scenarios ranging from very strong to very weak cases. We then illustrate how the amplitude-space sharing strategy can be applied to the multiple pico-cell scenarios by developing a simple transmission scheme. Simulation results show the superiority of the proposed scheme over other interference management schemes.