NETWORK CONFIGURATIONS FOR SEAMLESS SUPPORT OF CDMA SOFT HANDOFFS BETWEEN CELL CLUSTERS

Current code division multiple access (CDMA) networks do not support s oft handoffs between cell clusters serviced by different mobile switch ing centers (MSC's), Three novel network configurations are proposed t o overcome this limitation, Configurations I and II employ crosslinks to allow diversity combining of signals, This is accomplished in Confi guration III by linking the modified MSC's serving adjacent cell clust ers, In Configuration I, a scheme which reduces the handoff blocking p robability by lengthening the handoff transition time is proposed. Con figuration II expands overlapping regions of adjacent cell clusters, t hus enabling the use of different intercluster handoff regions for dif ferent handoff directions to prevent oscillations which may occur in C onfiguration I, while reducing the necessary number of intercluster ha ndoffs, Configuration III fully shares the trunks to support the highe st number of calls among all three configurations, A new mobility mode l for microcells is developed to enable dimensioning of the trunk grou ps in each configuration, For Configurations I and II, the optimal par titions of trunk groups into direct and crosslinks are determined by m athematical analyses and computer simulations, For Configuration III, the optimal number of trunks required to interconnect adjacent MSC's i s investigated by computer simulations, The new call and handoff block ing probabilities in all of these configurations are compared.