Interference in dynamic TDD: Effect of MIMO rank on DoF and transceiver design

Dynamic Time Division Duplexing (DynTDD) is a system that provides greater flexibility than static TDD by allowing for the dynamic adjustment of time slot allocation based on changing communication needs. However, this flexibility can be limited by cross-link interference (CLI) arising from neighboring cells that use different transmission directions on the same or partially-overlapping timefrequency resources. To mitigate this interference, coordinated beamforming is a critical signal-processing technique. This study focuses on the design of zero-forcing (ZF) transmit beamforming at initialization, with and without water-filling, as well as the iterative weighted minimum mean-square error (WMMSE) algorithm to maximize the sum rate in a Multiple Input Multiple Output (MIMO) User Equipment to User Equipment (UE-to-UE) Interference Channel (IC). Additionally, the study explores the potential benefits of nonuniform Degrees-of-Freedom (DoF) at Uplink (UL) and/or Downlink (DL) Users Equipment (UEs), which can increase the sum of Degrees of Freedom (DoF), resulting in a higher sum rate at a high Signal-to-Noise Ratio (SNR).