X-Duplex Radios: Flexible Switching Between Full-Duplex and Half-Duplex

Full duplex (FD) has the potential to achieve full sum rate, but in practice, may be affected by the self interference, i.e., a loop-back interference from the transmit module to its receive module, while half duplex (HD) can avoid the self interference at the expense of lower resource efficiency. In this letter, we study a novel X-duplex scheme with two bidirectional transmission nodes. Each node is equipped with a shared antenna and two radio frequency chains used for transmission and reception. By adaptively configuring the antenna as either transmit or receive antenna, the system can operate in either FD or HD mode. The X-duplex scheme can select the optimal mode to maximize the system sum rate by dynamically configuring the antenna mode. By deriving the distributions, we investigate the system sum rate of the X-duplex scheme, and demonstrate its superior performance compared to the pure HD and FD modes. Simulation results validate our analysis.