Question

A metropolitan area is to be given wireless digital telephone service. Throughout this area there is approximately uniform service demand. Assume that the frequency is allocated in two blocks of \(4 \mathrm{MHz}\) with a separation of \(50 \mathrm{MHz}\), one block for the uplink and the other for the downlink, which constitutes a frequency-division duplex (FDD) operation. The system uses the hybrid frequency-division time-division multiple access (FD/TDMA) schemes as follows: The frequency band is divided into \(500 \mathrm{kHz}\) "channels" (which is the frequency division part), and on each of those "channels" a total 40 high - quality digital voice circuits are multiplexed in a TDMA manner.

a) The modulation scheme used is \(8-\mathrm{QAM}\) which is implemented with the square-root- raised cosine pulses with a roll-off factor,  α of 0.25 . Find the bit rate for each user.

Hint: \(R_{s}=w / 1+\alpha,\) where \(R_{s}\) is the rate and \(\mathrm{w}\) is the bandwidth.