2.5.1 CAS Handling Handovers

A handover is defined as a change of radio channel used by a mobile terminal. The new channel may be within the same cell (intracell handover) or in a different cell (intercell handover). A handover can be initiated by channel reallocation or by link degradation. They are an important issue in microcellular systems, where the cell radius is small, because the performance of such systems depends significantly on the number of handovers performed by mobile users. Of particular interest in these systems is the reduction of calls forced to terminate, because from both the user and the service provider point of view, it is less desirable to force an ongoing call to terminate than to block a new call. Therefore, methods for decreasing the probability of forced termination by prioritizing handovers at the expense of a tolerable increase in call blocking probability have been devised in order to increase the quality of cellular service [18, 62 69]. These methods are the NPS [63], the RCS [62, 63], the first in first out (FIFO) priority scheme [67], the measured based priority scheme [67], and the subrating scheme (SRS). They are classified into three categories: basic, queuing [66], and subrating [64].

There are no restrictions on combining any of these channel allocation strategies for handover with any of the FCA, DCA, or PICA strategies...