Resource allocation for asymmetric traffic in time division duplexing mode cellular networks

Sammanfattning: Time Division Duplexing (TDD) mode systems provide greatflexibility that can be used to implement asymmetrical links.Adverse interference conditions easily arise, however.Especially if dicerent asymmetries are required in neighbouringcells.This thesis examines the feasibility of supportingasymmetric links in a locally centralised system in a Manhattanenvironment. Methods to avoid inter-mobile and inter-basestation interference are studied and possible performance gainsare assessed. Further, the implications of having differentasymmetries in neighbouring cells and the importance of thebase station placement are investigated.The thesis shows that asymmetric traffic can be provided inTDD mode systems with a locally centralised resource allocationscheme. Capacity is increased noticeably when compared to asystem with a fixed global asymmetry. Careful handling ofinter-mobile station interference is of great importancethough, to keep outage reasonably low. Measuring link-gainsbetween mobile stations is considered infeasible. However, itis shown that outage can be reduced significantly by using somesimple allocation rules and link-gain estimates proposed andevaluated in the thesis. Results also show that it is possibleto have different asymmetry ratios in different parts of thesystem, though large asymmetry differences between neighbouringcells will adversely affect capacity. Where base stations areplaced is important for system capacity, but as long as thebase stations are not placed in the intersections, the exactlocations are not critical.