# Homework 2

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```					ConEd-TCOM1010-Spring-2009                        Cellular Mobile Systems and Services

Homework 2

1.   A cellular system is to be designed for an area. The system designer decided to have 19-cell clusters to cover the cluster

Duplex Bandwidth allocated to the system = 20 MHz
Bandwidth of each frequency channel = 200 kHz
Number of traffic channel per frequency channel = 8
Busy hour Grade of Service (blocking probability) = 0.1%
Busy hour Average holding time = 1.5 minutes
Busy hour probability of making a call by an user = 0.6 (60%)
Propagation path loss = 40 dB/decade

Calculate:

a.   Total number of traffic channels per cluster
b.   Number of traffic channel per cell
c.   Erlang value per cell
d.   Arrival rate in a cell
e.   Number of user
g.   Cochannel interference (C/I) in dB (make appropriate assumptions, if required)

a. What is TRAU? Where is it located? Why does a GSM system need a TRAU?
b. Why is a GSM system’s cell radius limited to 35 km?
c. Why do the traffic multiframe and control multiframe have different sizes/lengths?
d. What are the purposes of using interleaving and frequency hopping in a GSM system?
e. A CSD data rate can be 4.8, 9.6 and 14.4 kbps. What makes this difference?
f. A HSCSD data rate can be as high as 57.6 kbps. How does HSCSD achieve higher bit-rate than the CSD?
g. EGPRS achieves much higher bit rate than the HSCSD. List the techniques that are used in EGPRS to enhance
the bit rate.

c6143040-e3ff-40e8-9d11-8a8d055d0abc.doc          Dr. Monzur Kabir, P.Eng.                                          Page 1 of 1

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