## 1. Consider a QAM system over an AWGN channel. Let the maximum symbol rate be Baud. Determine: a)…

1. Consider a QAM system over an AWGN channel. Let the maximum symbol rate be

Baud. Determine:

a) The required modulation cardinality, M, and ratio Es/N0, in dB, to guarantee a bit error probability of

with a bit rate

b)

a) when Rb = 8 kbit/s and Rb = 16 kbit/s and draw some conclusions.

2. Consider the two constellations of the figure below where the minimum distance between constellation points is A.

a) Is it possible to devise a Gray bit mapping for the above 8-QAM constellation?

b) Determine the required symbol rate if the system bit rate is Rb = 60 Mbit/s.

c) Compare the SNR Es/N0 required for obtaining the same bit error probability in a 8-QAM and a 8-PSK system (assume that the expression in is valid for 8-QAM).

d) Which of the constellations in figure is more robust to phase errors – errors in the phase of the received vector r?