Packet throughput analysis of static and dynamic TDD in small cell networks

We develop an analytical framework for the performance comparison of small cell networks operating under static time division duplexing (S-TDD) and dynamic TDD (D-TDD). By leveraging stochastic geometry and queuing theory, we derive closed-form expressions for the uplink (UL) and downlink (DL) packet throughput, also capturing the impact of random traffic arrivals and packet retransmissions. Through our analysis, we confirm that: 1) the number of scheduled user equipment may strongly affect the network throughput and 2) D-TDD outperforms S-TDD in DL, with the vice versa occurring in UL, since asymmetric transmissions reduce DL interference at the expense of an increased UL interference. We also find that in asymmetric scenarios, where most of the traffic is in DL, D-TDD provides a DL packet throughput gain by better controlling the queuing delay, and that such gain vanishes in the light-traffic regime.