Q:What are bursts? Explain various types of bursts.

Burst

A term, usually associated with a TDMA system, describing a group of bits or other

information transmitted by the system. Also refers to the time the transmitter is on and radiating.

The

normal burst (NB)

: Used to carry information on traffic and control channels, except

for RACH. It contains 116 encrypted bits.

The

frequency correction burst (FB

): Used for frequency synchronization of the mobile.

The contents of this burst are used to calculate an unmodulated, sinusoidal oscillation, onto

which the synthesizer of the mobiles is clocked.

The

synchronization burst (SB)

: Used for time synchronization of the mobile. It contains

a long training sequence and carries the information of a TDMA frame number.

The

access burst (AB)

: Used for random access and characterized by a longer guard period

(256 ms) to allow for burst transmission from a mobile that does not know the correct

timing advance at the first access to a network (or after handover).

The

dummy burst (DB)

: Transmitted as a filler in unused timeslots of the carrier; does not

carry any information but has the same format as a normal burst (NB

Q: What do we mean by E1 and T1?

E1 carrier

It is a PCM  carrier having a data rate of 2.048 Mbps. This carrier has 32 8-bit samples

packed into the basic 125 usec frame.

T1 carrier

The T1 carrier consists of 24 voice channels multiplexed at a rate of 1.544 Mbps

1. What are the three services offered by GSM? Explain each of them briefly.

GSM PLMN Services

Bearer Services

Thse services give the subscriber the capacity required to transmit appropriate signals b/w

certain access points(i.e., user-network interfaces).

Teleservices

These services provide the subscriber with necessary capabilities including terminal equipment

functions to communicate with other subscribers.

Supplementary Services

These services modify or supplement basic telecommunications services. These services are

offered together or in association with basic telecommunications services