Evaluation of teletraffic in cellular communication systems using multi-connections for soft handoff

To implement soft handoff in cellular communication systems that employ cod e division multiple access (CDMA), it is necessary to establish communicati on lines between the switch and multiple base stations and distribute the c ommunication data via these multi-connections to the base stations simultan eously. This means that, when soft handoff is performed with the same amoun t of communication line resources as hard handoff, the blocking probability is higher than for hard handoff, and service quality is thus worse. Furthe rmore, handoffs occur more frequently as the size of cells becomes smaller, and tills increases the probability of forced terminations. Switches must be endowed with greater processing capacity to accommodate the more frequen t handoffs. The use of the queuing handoff method can be expected, in gener al, to mitigate forced termination probability compared with the immediate handoff method. In this regard, we propose a prioritized queuing handoff me thod that gives priority to fast-moving mobile stations (MSs) as a way to m itigate forced terminations even more than the non-priority queuing method without appreciably increasing the processing load. We then compare the tra ffic characteristics of our proposed method with these of three other metho ds in micro cell systems-immediate method, non-priority queuing method, and conventional hard handoff method without multi-connections-by computer sim ulation. Here, considering that the proposed method gives priority to fast- moving calls, traffic characteristics for these methods were evaluated sepa rately for slow- and fast-moving MSs. The results reveal that proposed meth od can reduce the forced termination probability and total call failure pro bability more than non-priority queuing method without having an appreciabl e impact on slow-moving calls.