Measurement-based replanning of GSM cell capacities considering retrials, redials and hand-offs

During the optimization of the Global System for Mobile Communications (GSM) network, the operations and maintenance center (OMC) measurements are of significant importance. Because of false predictions, the capacity planning of a cell may be done inaccurately. If the capacity of the cell is not adequate to handle all of the busy-hour requests, the requests are not granted a channel and users are blocked. Thus, when the blocking ratio is high, the cellular capacity should be replanned. However, the capacity planning should not rely on the raw OMC measurements since these are inflated by the redials and retrials of fresh calls, as well as the retrials of the hand-off call attempts. In this paper, we provide a simple-to-implement analytical model that computes the average number of retrials and redials per original call attempt using only the OMC statistics. The effective load is then determined through appropriate scaling. That way, unnecessary waste of channels to sustain the retrials and redials is avoided during the cellular capacity replanning phase.