Problem
1. Since all IS-95 base stations use the same short code, this simplifies the acquisition procedure for the mobile terminal. To ensure that there is no ambiguity among base stations, their short codes are offset in time. If 40 km is the maximum separation between base stations, what is the minimum time offset between the short codes of the two base stations that will prevent them from aligning in the coverage area. How many distinct timing offsets of this size are there?
2. The short PN code of IS-95 is of length 215 -1 chips with a chip rate of 1.228g MHz. Show a block diagram of a circuit that could be used to recover the short-sequence timing, Suppose the receiver oscillator has an accuracy of 10 ppm. How would this affect your design?