Improved TDD Resource Allocation through Inter-Mobile Interference Avoidance

Time division duplex systems, in a convenient way, facilitate the implementation of asymmetrical links which are required to efficiently handle the increasingly asymmetric traffic offered by current and future wireless applications. If boundaries between uplink and downlink time-slots are not synchronised among cells, e.g. when different asymmetries are required in different cells, Inter-Base station (IB) interference and Inter-Mobile (IM) interference arise. To keep the outage probability at a reasonable level this interference needs to be avoided. In a system with centralised resource allocation, information about IM link gains can be used to estimate IM interference. Measuring all IM link gains is often considered to be an intractable task. Thus, in this paper a simple method to estimate IM link gains and to avoid IM interference is proposed and evaluated. In centralised system, for the critical case of heavier downlink traffic, the new method significantly improves system capacity.