Realization and optimization of soft and softer handover in UMTS networks

With the use of user dependent spreading codes in wideband code division multiple access (W-CDMA) networks and the application of multipath aware radio receivers, a novel type of handover execution becomes possible. The soft and softer handover describes the situation in which a mobile terminal communicates with the radio access networks via two or even more different links. Instead of breaking an existing connection to an old base station and establishing a new connection to one neighbouring base station, soft handover seamlessly adds another radio link as a parallel connection. Soft handover parameters, regions, and performance issues are discussed. Results are obtained in an analytical manner as well as by means of dynamic simulation, both considering a realistic dense urban area scenario.