Design and Analysis of Full duplex Systems for Next generation Wireless Communication Systems

Abstract

To cater to the ever-growing demand for higher data rates, cellular networks and wireless local area networks (WLANs) need to adopt innovative technologies. Full-duplex (FD) is one such technology that promises to double the data rates by enabling simultaneous transmission and reception over the same frequency band. However, FD raises its own challenges. The first challenge is self-interference (SI) at the FD receivers due to power leakage from the collocated transmitter. Recent advances that employ techniques such as analog and digital domain signal cancellation and electromagnetic isolation of the receiver and the transmitter suppress SI below the noise floor, thereby making FD viable. The second challenge is inter-user interference due to the simultaneous uplink and downlinks in cellular networks and WLANs with FD-capable base stations (BSs) or access points (APs) and half-duplex (HD) users. It can degrade the downlink signal-to-interference- plus-noise ratio (SINR). In cellular networks, effective user-pair scheduling and mode selection algorithms are needed to mitigate it. In user-pair scheduling, the BS determines which users are scheduled on the uplink and the downlink. In mode selection, the BS selects either the FD mode or the HD mode for operation, depending on the feasibility. Since these decisions are taken based on the inter-user interferences between the users and these channels are not connected to the BS, the users need to feed them back. In a cell with N users, there are (N, 2) inter-user links, which can overwhelm the uplink. To limit the feedback overhead, we first propose a novel reduced feedback scheme in which a user feeds back the channel gains of a limited number of inter-user channels that are below a threshold and the corresponding user indices. Then, we propose a user-pair scheduling and mode selection algorithm (UPSMA). In UPSMA, the BS schedules a user based on the uplink and downlink SINRs...