Performance Trade-off Between Uplink and Downlink in Full-Duplex Communications

In this paper, we formulate two multi-objective optimization problems (MOOPs) in orthogonal frequency-division multiple access (OFDMA)-based in-band full-duplex (IBFD) wireless communications. The aim of this study is to exploit the performance trade-off between uplink and downlink where a wireless radio simultaneously transmits and receives in the same frequency. We consider maximizing the system throughput as the first MOOP and minimizing the system aggregate power consumption as the second MOOP between uplink and downlink, while taking into account the impact of self-interference (SI) and quality of service provisioning. We study the throughput and the transmit power trade-off between uplink and downlink via solving these two problems. Each MOOP is a nonconvex mixed integer non-linear programming (MINLP) which is generally intractable. In order to circumvent this difficulty, a penalty function is introduced to reformulate the problem into a mathematically tractable form. Subsequently, each MOOP is transformed into a single-objective optimization problem (SOOP) via the weighted Tchebycheff method which is addressed by majorization-minimization (MM) approach. Simulation results demonstrate an interesting trade-off between the considered competing objectives.