Cross-Link Interference Cancellation and Network Power Optimization With an FD Base Station

Abstract

Engineering breakthroughs in self-interference cancellation have advanced full-duplex (FD) networking from theoretical research to practical deployment, alleviating the spectrum supply-demand imbalance. However, the co-time co-frequency transmission for the uplink and downlink intensifies inter-user cross-link interference (CLI), yielding downlink signal-to-noise ratio degradation and network rate reduction. In this study, a CLI cancellation strategy is proposed by leveraging one FD base station to perform amplitude-phase adjustment and real-time forwarding on received uplink signals, at the cost of slightly elevating the noise power at user terminals. Besides, the CLI cancellation performance is evaluated via the network achievable rate, and the mathematical expectation and cumulative distribution function of the network achievable rate are derived by modeling the time error as an unknown constant and the channel error as a zero-mean complex Gaussian variable. With errors considered, the proposed strategy still achieves an average achievable rate enhancement of about 5.6 bps/Hz compared to the traditional FD scheme. Finally, two network power schemes are optimized for two complementary targets: 1) Maximize the network achievable rate under a network outage probability threshold. Compared to the fixed-power scheme and traditional FD scheme, the proposed scheme achieves a network sum rate enhancement of approximately 9 bps/Hz and 16 bps/Hz, respectively. 2) Minimize the network outage probability under a network achievable rate threshold. The proposed scheme reduces the outage probability by 30.3% compared to the traditional FD scheme and by 16.1% compared to the fixed-power scheme.