Visvesvaraya Technological University (VTU) 2007 B.E Computer Science on mobile communications - Question Paper

near/far issue. How does this complicate the situation? What would be possible
countermeasures?
4. Telecommunication systems
4.1 Name a few key features of the GSM, DECT, TETRA, and UMTS systems. Which
features do the systems have in common? Why have the older 3 various
systems been specified? In what scenarios could 1 system change another? What
are the specific advantages of every system?
4.2 elaborate the main issues when transmitting data using wireless systems that were
made for voice transmission? elaborate the possible steps to mitigate the issues
and to raise efficiency? How can this be supported by billing?
4.3 Which kinds of various services does GSM offer? Name a few examples and provide
reasons why these services have been separated.
4.4 Compared to the TCHs offered, standard GSM could give a much higher data rate
(33.8 kbit/s) when looking at the air interface. What lowers the data rates available to
a user?
4.5 Name the main elements of the GSM system architecture and define their
functions. elaborate the advantages of specifying not only the radio interface but also
all internal interfaces of the GSM system?
4.6 define the functions of the MS and SIM. Why does GSM separate the MS and
SIM? How and where is user-related data represented/stored in the GSM system?
How is user data protected from unauthorised access, especially over the air
interface? How could the position of an MS (not only the current BTS) be localised?
Think of the MS reports regarding signal quality.
4.7 Looking at the HLR/VLR database approach used in GSM—how does this
architecture limit the scalability in terms of users, especially moving users?
4.8 Why is a new infrastructure needed for GPRS, but not for HSCSD? Which
components are new and what is their purpose?
4.9 elaborate the limitations of a GSM cell in terms of diameter and capacity (voice, data)
for the traditional GSM, HSCSD, GPRS? How can the capacity be increased?
4.10 What multiplexing schemes are used in GSM for what purposes? Think also of other
layers apart from the physical layer.
4.11 How is synchronisation achieved in GSM? Who is responsible for synchronisation
and why is synchronisation very important?
4.12 elaborate the reasons for the delays in a GSM system for packet data traffic?
Distinguish ranging from circuit-switched and packet-oriented transmission.
4.13 Where and when can collisions occur while accessing the GSM system? Compare
possible collisions caused by data transmission in standard GSM, HSCSD, and

Earning:   Approval pending.