Reduced feedback, user scheduling, and mode selection in asymmetric full-duplex systems

Abstract

In a full-duplex (FD) system, the base station (BS) needs to carefully schedule the uplink and downlink users that transmit simultaneously to control the inter-user interference. The efficacy of scheduling is closely tied to the availability of channel state information and the feedback scheme that conveys it to the BS. We propose a novel user-pair scheduling and mode selection algorithm (UPSMA) and a reduced feedback scheme, in which a user feeds back only a limited number of inter-user interferences that are below a pre-specified threshold. We derive expressions for the uplink and downlink rates of UPSMA in the presence of small-scale fading, large-scale shadowing, and pathloss. These lead to novel scaling laws for the threshold and the uplink and downlink rates. Even with limited feedback, UPSMA achieves a higher sum rate compared to a half-duplex system and conventional FD resource allocation algorithms.