Method for initiating call blocking based upon pilot fraction

Abstract

A method that initiates call blocking responsive to a call-quality measurement of the forward link. The call-quality measurement is a measurement of how well a mobile terminal is able to receive the forward link. One call-quality measurement is a pilot fraction of the forward link, which is a ratio of the pilot's power level to the power level of a set of forward-link signals of a base station. Call blocking is initiated when an average pilot fraction is below a pilot-fraction blocking threshold. The pilot's power level is obtained for a time period, and the signal set's power level is obtained for the same time period. The pilot fraction is determined for the time period, and then used to determine the average pilot fraction for the time period. The average pilot fraction for the current time period is based on a pilot fraction for the current time period, and an average pilot fraction for a previous time period. When the average pilot fraction is below the pilot-fraction blocking threshold, call blocking is initiated. The pilot-fraction blocking threshold is preferably based on: 1) the pilot fraction when the base station is at full load; 2) the size, shape, and terrain of the cell; and 3) the aggressiveness of the overload control. In the preferred embodiment, the signal set includes all of the signals generated by the base station, alternatively, the signal set can include fewer than all the signals generated by the base station. If the cell includes several sectors, the call blocking is initiated on a sector basis when the average pilot fraction of the sector is below the pilot-fraction blocking threshold. Other call-quality measurements, such as the forward link's frame error rate, the number of dropped calls, or the Power Measurement Report Message (PMRM), can be used, alone or in combination, instead of or in addition to the pilot fraction of the forward link to determine whether call blocking should be initiated. Determining whether call blocking should be initiated using one of the other call-quality measurements is performed in a similar manner as for the pilot fraction. Initiating call blocking using several call-quality measurements involves initiating call blocking when any one of the call-quality measurements indicates that call blocking should be initiated. Alternatively, call blocking can be initiated when several of the call quality measurements indicate that call blocking should be initiated.

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