Answer 6.9
- A 256-QAM system can convey n = log2(256) = 8
bits per symbol resulting in a symbol rate of 4 million symbols per second for a 32 Mbps
data rate. For a bandpass modulation system, this requires a minimum bandwidth of 4 MHz
for brick-wall filtering.
As the actual bandwidth used is 7 MHz, this implies the use of pulse shaping with a filter having an a given by:
(1 + a) = 7 / 4
= 1.75
Therefore, a = 0.75.
- The Shannon-Hartley equation gives us the required
relationship between channel capacity in bits/second, the bandwidth and the signal to noise ratio as
follows:
Channel capacity C = B log2(S / N + 1) bits/second
Therefore, C = 7 · 106 log2(10000 + 1) bits/second
= 93 Mbps