Time slot allocation based on a path gain division scheme for TD-CDMA TDD systems

TD-CDMA TDD technique allows UMTS to utilize the bandwidth and the rare radio resource more efficiently if dynamic channel allocation is used. This technique is suited especially for systems that offer highly asymmetric services. However, the rate of symmetry is not the same in all cells. Hence, it is possible that in some slots, called crossed slots, a set of cells is active in downlink and another set is active in uplink. Inter-BS and inter-MS interferences arise in these slots and can degrade dramatically the QoS. In this paper, we introduce a scheme to prevent mobiles that can introduce very high inter-mobile interference from being active during crossed slots. In this scheme, a mobile can be active during a crossed slot with mobiles of a neighboring cell, if the path gain between the mobile and the neighboring base station is less than a given threshold. For high loads, this scheme has shown better results than common switching point technique where crossed slots are forbidden and other interference avoidance methods.