Design of user selection algorithm in full-duplex cellular system

Abstract

We propose a user selection algorithm for full-duplex cellular system. In full-duplex cellular system, besides self-interference (SI), the user-equipment (UE)-UE interference at downlink (DL) users is induced by adjacent uplink (UL) users thereby degrading the performance severely. Thus, we alleviate the UE-UE interference and improve the achievable rate of UL users at the same time by means of our proposed user selection algorithm. Specifically, we first select DL users adopting semiorthogonal user selection (SUS) algorithm [17] with ZF precoder. After the DL users selection is done, proposed user selection algorithm selects UL users considering the trade-off between increasing the rate of UL users and decreasing the UE-UE interference. However, all UL user candidates fail to be selected if every UL user candidate decreases the sum-rate of our full-duplex cellular system when selected as an actual UL user. With this constraint, proposed user selection algorithm can successfully reduce the energy. Moreover, we also propose a mode selection based on our proposed algorithm. As a result, we provide the improved achievable sum-rate of full-duplex system as guaranteeing better achievable rate for both DL and UL users, compared with those of users in half-duplex system. In addition, we analyze the complexity of the proposed user selection algorithm along with analysis of full-search algorithm. In the end, our numerical results show that the proposed user selection algorithm improves not only the achievable sum-rate but also the energy efficiency (EE) compared with the other user selection algorithms.