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.
problem 2:
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(2πf_{c}t + 4 cos 2πf_{m}t). Assume that frequency modulation. The message frequency f_{m} = 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.