Performance of a CDMA-based HCS network with hybrid speed/overflow-sensitive handover strategy

In a mixed cell architecture, in which cells of different sizes co-exist, the interaction between layers has a major impact on radio resource management. Such interaction can be in terms of directing the traffic overflow from the lower layer to the overlaying layer (overflow-sensitive handover) and/or of classifying the users based on their speed (speed-sensitive handover). In this study, the implementation of a hybrid speed/overflow-sensitive layer assignment strategy in a CDMA-based hierarchical cell structure (HCS) network is studied and its impact on the signalling load and capacity of the system is compared with three other assignment strategies. A new approach to controlling the signalling load in such a network is also proposed. The results indicate that by using the proposed strategy, the signalling load can be controlled even in an area in which the mobile stations have a time-varying speed distribution.