ERROR STATISTICS OF REAL-TIME POWER MEASUREMENTS IN CELLULAR CHANNELSWITH MULTIPATH AND SHADOWING

Real-time power measurements performed by cellular receivers are essen tial for power control, handoff, and dynamic channel allocation. For b est results, the measurement filter bandwidth must be sufficiently nar row to average out multipath fluctuations, yet sufficiently wide to fo llow shadow fading fluctuations. Our study considers two measurement m ethods (filtering the squared envelope, and filtering the logarithm of the squared envelope), and two filter types (integrate-and-dump and R C). We show, using standard models for the multipath and shadow fading s, that the dB measurement error tends to be Gauss-distributed, and ca n readily be made unbiased (zero mean) by proper amplitude calibration . The performance metric then becomes the standard deviation (DELTA) o f the dB error, which can be minimized by proper choice of the filter bandwidth. We find that DELTA can be kept to values of 3 dB or lower o ver a wide range of mobile velocities and shadow fading characteristic s. Also, we discuss the potential gains in measurement accuracy associ ated with diversity reception and broad-band channels.