(b) A 900 MHz digital cellular network has the following characteristics: ink of 925-945MHz R-F channel spacing=400kHz number of time slots per R.F channel=8 Determine the: (i) channel bandwidth; (ii) number of up-link RF channels; (iii) total number of up-link TDM channels. (7 marks)

$(i)$ Channel bandwidth:<br />The channel bandwidth is the difference between the upper and lower frequencies of the channel. In this case, the channel bandwidth is:<br />$945MHz - 925MHz = 20kHz$<br /><br />$(ii)$ Number of up-link RF channels:<br />The number of up-link RF channels can be calculated by dividing the total frequency range available for the up-link by the channel spacing. In this case, the total frequency range available for the up-link is:<br />$945MHz - 925MHz = 20MHz$<br /><br />So, the number of up-link RF channels is:<br />$\frac{20MHz}{400kHz} = 50$<br /><br />$(iii)$ Total number of up-link TDM channels:<br />The total number of up-link TDM channels can be calculated by multiplying the number of up-link RF channels by the number of time slots per RF channel. In this case, the total number of up-link TDM channels is:<br />$50 \times 8 = 400$<br /><br />Therefore, the channel bandwidth is $20kHz$, the number of up-link RF channels is $50$, and the total number of up-link TDM channels is $400$.