problem 1: A cellular system has a total of 500 duplex voice channels. The service area is divided to 150 cells. Recommend a three different cluster size (N) values. In each case, find out:
a) The number of cell clusters,
b) the maximum number of users which can be served simultaneously,
c) Discuss the effect of cluster size on the whole system capacity.
a) Describe how a CDMA system works?
b) Describe how Welsh-Hadamard codes are generated. Describe why orthogonality between different spreading codes is significant.
c) Consider an 8-user CDMA system.
The data vector of all users is given by: [1,1,1,1,-1,-1,-1,1].
Find out the total transmit signal.
problem 3: Consider a signal x(t) = 10 cos(2πfct + 4 cos 2πfmt). Assume that frequency modulation. The message frequency fm = 2:3 kHz. Compute the modulation index and find the bandwidth when
a) fm is doubled and
b) fm is reduced by one-half.
problem 4: A carrier is frequency modulated with a sinusoidal signal of 2 kHz, resulting in a maximum frequency deviation of 5 kHz.
a) Find out the bandwidth of the modulated signal (b) The amplitude of the modulating sinusoid is raised by a factor of 3, and its frequency is lowered to 1 kHz. Find out the maximum frequency deviation and the bandwidth.