Method and apparatus for evaluating a received signal in a wireless communication utilizing long and short term values

DETAILED DESCRIPTION It is therefore an object of the invention to provide a dual stage method and apparatus for accurately evaluating a received signal by providing a mobile station with a concise and consistent measure of a received signal strength, in order to perform such tasks as determining a signal strength based trigger to reselect a control channel (CCH) or a traffic channel.
It is a further object of this invention to determine the signal strength based trigger at the appropriate coverage point and in a manner that overcomes the shortcomings found in single stage (short or long term) received signal evaluation approaches.
It is an object of the invention to avoid poor trigger decisions caused by the highly fluctuating nature of the signal, e.
g.
short term fades in the signal, as well as to eliminate the occurrence of false triggers caused by the historical bias that may exist from a long term averaging process.
It is a further object of the invention to avoid premature handoff decisions due to the effects of short fades on the signal.
It is a further object of the invention to avoid a handoff decision that is not sufficiently reactive to a true handoff condition due to the relatively large latency that may exist between short term measurements.
It is also an object of the invention to address the problem of delaying the handoff due to an adjacent cell measurement being unable to exceed the historically biased long term average signal strength representation found in a pure averaging system.
A dual stage approach may be used to indicate a signal strength based trigger condition when the strength of the received signal from the serving control channel falls below a predetermined threshold or when the strength of a neighboring control channel is above a predetermined threshold.
These and other objects of the invention are accomplished by maintaining both a long term representation of the signal and a short term representation of the current signal level.
A signal strength based trigger condition exists if both the long term average and short term value exceed a predetermined threshold