Analysis Of Spectral Efficiency In Hybrid Networks With Full Duplex Base Stations And Tdd Users

In the asymmetric and time-variant traffic, the hybrid network with a full duplex (FD) base station (BS) and multiple time division duplex (TDD) user equipment (UE) is more flexible than the traditional TDD network, since it is not limited by the fixed TDD frame structure. This paper focuses on the specific hybrid network with FD BS and TDD UE. First, applying the hybrid network must ensure that the intra-cell co-frequency interference (CI) has been suppressed. To achieve this goal, a spatial isolation method and its corresponding resource allocation are proposed in the specific hybrid network with FD BS and TDD UE. Then, to evaluate the gain of the hybrid network compared with the TDD network, the spectral efficiency is derived and analyzed. Theoretical and simulation results show that the gain of hybrid network increases with the number of users and decreases with the number of sub-regions when compared with the TDD network. Furthermore, the uplink gain increases with the ratio of the number of time slots for the uplink to that for the downlink (UDR) in the TDD frame, and can be greater than 2 when UDR is adequately small, while the downlink is reversed. However, the total gain of spectral efficiency is smaller than 2, which is the FD upper bound restricted by FD system structure. Therefore, when compared with the symmetric and time-invariant traffic, it is more efficient to apply FD in networks with asymmetric and time-variant traffic where the performance of the TDD network is severely limited.