Dynamic TDD for LTE - A and 5 G

In recent years, mobile communication traffic has continuously been shifting from being dominated by voice-call traffic with symmetric uplink / downlink capacity requirements to burst-like traffic with strongly fluctuating capacity requirements depending on instantaneous file upload / download activities by mobile users. Consequently, LTE, which was originally designed with fixed FDD or TDD modes with little flexibility for varying the capacity split between uplink and downlink, is being augmented with features that allow for more flexible use of radio resources. One of these features is “enhanced Interference Mitigation and Traffic Adaptation” (eIMTA) which notably allows for very dynamic adaptation of the TDD pattern e.g. in response to varying capacity requirements in uplink and downlink. eIMTA was standardized in LTE-A Release 12 and eIMTA-like functionality is considered to be one of the key enablers for 5G technologies. The purpose of this paper therefore is to shed some light on eIMTA, its main characteristics and capabilities and to illustrate its behaviour by means of system-level simulations.