Mobility Optimization Of LTE-A For Carrier Aggregation

This paper derives from the cooperation project of Huawei Technologies Co., Ltd and Beijing University of Posts and Telecommunications, "Huawei wireless standard Radio Resource Management R & D projects." Project aims for the fourth generation mobile communication standard 3 GPP LTE-A technical standards pre-research which concentrates theoretical study and simulation verification on LTE-A RRM (Radio Resource Management), output contributions to 3 GPP conference to promote the standards of progress. This thesis focuses on mobility management technology which is part of Radio Resource Management.To meet the fourth generation mobile communication system requirements and breakthrough the single-carrier bandwidth limitation (20MHz),3GPP introduces a new technique feature; CA (Carrier Aggregation). The introduction of new technology feature to the system has brought great improvement on the performance while also introducing many new challenges to be solved. This paper focuses on the impact to the mobility of LTE-A radio communication system after the introduction of CA. Carriers with mo fixed number which must be more than one are configured to network and UE (User Equipment) for communication will increase the mobility measurement cost directly. And because of the technology limit and costs, the RF part of the receiver equipped on UE will be certainly far less than the number of available carriers. It must result that the most part of mobility measurement are Inter-Frequency measurement which cost more time to implement than the Intra-Frequency measurement, which will greatly extend the measurement time delay and make the system to be unable to meet the delay requirements of LTE-A. At the same time, as each carrier's wireless transmission characteristics and different load conditions, the time of triggering the measurement result report event must be different. This will result that the network cannot get all the information and make rational decisions timely. In this thesis, two issues were raised for the corresponding improvements. One is the compressed frequency measurement method, by using the correlation between carriers to reduce the cost of UE measurement cost; another one is the multi-carrier adaptive hysteresis selection, by calculating to adapt the configuration of the corresponding hysteresis per carrier, so that all carriers could trigger measurement report even simultaneously to reduce the latency.