Performance of strong interference cancellation in flexible UL/DL TDD systems using coordinated muting, scheduling and rate allocation

Flexible UL/DL TDD can be used for efficient spectrum utilisation in 5G small cells. In this paper, we consider fully coordinated (centralized) scheduling which exploits interference cancellation in a cluster of small cells using flexible TDD. We study joint uplink-downlink scheduling, with coordinated link adaptation and/or muting in the flexible TDD system with successive interference cancellation receiver. This coordinated link adaptation is called rate allocation. The novelty is that a scheduler may purposely schedule strong interference situations, with muting and rate allocation decisions in the small cell cluster to facilitate effective interference cancellation. Simulation based packet delay performance is shown in an indoor small cell scenario, where high base station-to-base station interference impacts the uplink. Ideal and non-ideal channel estimation cases are considered. Comparison is made to the baseline centralized scheduling where muting is used for interference mitigation without interference cancellation. Results show that with ideal channel estimation, at a system load of 55% interference cancellation aware scheduling, muting with rate allocation outperforms other schemes. It achieves high gain of 67% in terms of packet delay reduction as compared to the baseline. Interference cancellation aware scheduling and muting with uncoordinated rate adaptation also achieves high gain around 62% at the same load using realistic channel estimation.