This invention relates to the selection of Base Station Transceiver Subsystems (BTS) at a CDMA cell site provisioned with multiple co-located BTSs, each operating independently on a dedicated carrier.
Typically, in present CDMA cellular telephone systems, one CDMA base station transceiver subsystem (BTS) is used for each cell. This is sufficient for low to medium traffic demands; however, under heavy demands additional base station transceiver subsystems are required to provide an acceptable level of service.
In a cellular telephone network employing a plurality of base station transceiver subsystems (BTS), typically, the assignment of a particular BTS which is to handle a call, is made by a base station controller having a selector bank subsystem which runs a radio link manager program for determining which of the BTS systems is to be used for a particular call. Currently, the assignment of a call to a particular BTS is made on the basis of whether or not the excess forward link capacity of the BTS exceeds a pre-set LoCall Blocking Threshold and whether or not there are free traffic channel elements available. In areas where there is high traffic demand, one particular BTS may therefore be called upon to service more calls than another BTS, to the point where no further calls can be handled by the loaded BTS, while excess capacity is still available at the unloaded BTS. Various prior art references deal with issues such as handoff boundary balancing, adding and removing a BTS in a network, etc., however, none appears to deal with the problem of concentrated loads on a particular BTS within a multiple BTS cell site. The present invention addresses this problem.