Problem
1. Suppose a spread-spectrum service is operating at 2 GHz and the maximum user terminal velocity is expected to be less than 80 km/hour. What should the bandwidth of the filter in the channel estimation circuit of the corresponding RAKE receiver be?
2. Suppose that a wireless service is operating at 800 MHz, with a maximum terminal velocity of 100 km/hour. What is the maximum transmitter-receiver separation that would permit reasonable power control compensation of Rayleigh fading, assuming that measurement and processing times are negligible? What would be negligible in this case? Ans. The maximum separation is 20 km, assuming that the tracking delay is less than 1 percent of a period of the maximum Doppler frequency. The measurement and processing delay must be significantly less than 135 AV satisfying this requirement is perhaps unrealistic.