Determining a reference power level for diversity handover base stations

Abstract

To combat base station power drift, the power transmission level of each base station in a diversity handover may be compared to a power reference established for all base stations in the diversity handover. The difference between the transmit power of each base station and the reference power threshold may then be used to correct the transmit power level of that base station. Because the power correction depends on the difference between the actual transmit power at the base station and the common power level reference, the various transmit powers of the different base stations in the diversity handover converge relatively quickly. Thus, even if the transmit power command from the mobile station is received in error in one or more of the base stations, the power correction based on the comparison to the common power reference compensates for such errors to reduce base station drift, obtain full diversity gain, and reduce unnecessary downlink interference. The reference power level(s) used in compensating for base station power drift is(are) advantageously determined using one or more parameters relevant to the current condition of the diversity handover communication. Rather than setting an arbitrary and static reference power level, the reference power level is set dynamically so that it is relevant to the current conditions of the diversity handover communication. Dynamic and adaptive reference power level setting results in more effective and more efficient downlink power control. Unnecessary power changes, both in frequency and in size, are avoided because the reference power level is more accurately determined for the current circumstances.