In DS-CDMA systems, soft handoff techniques provide seamless connections of mobile call between cells. The reserved capacity for soft handoff calls is required to sufficiently support calls in a soft handoff region. However, since the capacity required by soft handoff calls varies according to environmental factors, the conventional fixed reserved capacity can be excessive if the required channel capacity by soft handoff calls is small and this may cause a considerable amount of unnecessary blocking of new calls. We propose an adaptive channel reservation scheme which reserves channel capacity as much act necessary according to the variation of soft handoff requests. A simulation result shows that the blocking probability of new coils is reduced by 33% compared with the conventional fixed channel reservation scheme and that it is even larger as the offered load decreases or the maximum reserved capacity increases.
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