Capacity improvement through random timeslot opposing (RTO) algorithm in cellular TDD systems with asymmetric channel utilisation

In this paper the performance of the RTO algorithm at different asymmetries favouring uplink (UL) and downlink (DL) is studied. The RTO algorithm is a dynamic channel allocation (DCA) algorithm that yields a significant interference reduction (min. 3 dB, max. 20 dB) compared to a fixed channel assignment (FCA) algorithm. The FCA algorithm used, emulates an equivalent FDD system which has no same-entity interference. Thus, the existence of different interference modes in TDD is exploited constructively to avoid jamming. The RTO algorithm shows an excellent performance for an asymmetry favouring the DL. This is a very useful result as future high data rate services which, for example, make use of multimedia streaming technologies require significantly higher capacity in the DL than in the UL. If the asymmetry. for example, is 14:2 (14 time slots (TS's) used for DL and 2 TS's for UL). the performance is about 15 dB better than with an asymmetry of 2:12 (2 TS's used for DL and 14 TS's for UL). It is important to note that the FCA algorithm results in greater interference for all rates of asymmetry investigated.