Performance analysis of dynamic adjustment of TDD uplink-downlink configurations in outdoor picocell LTE networks

The dynamic adjustment of TDD UL-DL configurations to the instantaneous traffic conditions at small cells (e.g. Pico cells) in heterogeneous LTE networks can be used to further optimize the system performance. The dynamic adaptation of TDD configuration may result in opposite transmission directions in the neighboring cells and thus cause BS-BS and UE-UE inter-cell interference that may significantly affect the overall system performance. To avoid this problem all homogeneous Macro cell TDD deployments typically operate synchronously. However in heterogeneous networks low power small cells are rather isolated from each other in terms of mutual interference and thus can be considered as candidates for dynamic TDD adaptation. In this paper we investigate the possibility of using dynamic adjustments of TDD UL-DL configurations in application to outdoor Pico cell deployments. In particular, we show the feasibility of using opposite DL and UL transmission directions in neighboring Pico cells in terms of interference environment. Furthermore we evaluate the performance benefits from traffic adaptation in LTE TDD networks where cells can dynamically select TDD configuration and show that substantial gains in packet throughput performance may be achieved comparing to the traditional synchronous TDD networks.