Dynamic-TDD and optimum slot-allocation in fixed cellular systems

Dynamic TDD (D-TDD) has gained attention as a means to deliver high density two-way traffic. However, the outage performance of D-TDD system is severely limited by the strong interference from co-channel cells in a downlink cycle, while the reference cell is in its uplink duty cycle. To suppress the co-channel interference during uplink reception, we consider two kinds of time slot allocation strategies, combined with sector antennas: MaxMin (SIR) and Max (SIR). MaxMin (SIR) is an optimum time slot allocation strategy, in the sense that it maximizes the minimum signal to interference ratio expectation value over extra uplink time slot region. It is used as a performance benchmark in our analysis. Meanwhile, Max (SIR) is a simple and efficient algorithm to improve outage performance. It is established that the performance difference between the two algorithms is not noticeable, especially when the dynamic range of traffic pattern between the uplink and downlink is small. Also, outage performance comparison between Max (SIR) algorithm and adaptive array antennas is provided. The proposed system shows promise and offers a compromise between system complexity and the desired availability.