Exercise 3.2: GSM Services

From LNTwww

List of GSM services

Any  "Public Land Mobile Network"  $\rm (PLMN)$  must provide the fixed network infrastructure and so-called  "interworking functions"  $\rm (IWF)$.  This is the only way to provide the desired services at the user interface.

GSM services are divided into three categories:

  • Bearer services,
  • Tele services,
  • Supplementary services.


Basis for data transmission are the  bearer services,  where the maximum data rate is  $\text{9.6 kbits/s}$.

Tele services  are end-to-end services.  The most important of these are:

  1. the telephone service,
  2. the fax service,
  3. the short message service  $\rm (SMS)$.


Various  supplementary services  belong to each phase of GSM development:

  1. "call display",  "call forwarding"  and  "caller ID"  in phase 1,
  2. "call waiting",  "hold"  and  "conference call"  in phase 2,
  3. "GPRS",  "HSCSD",  "EDGE"  in phase 2+.


Hint:  The exercise belongs to the chapter  "General Description of GSM".



Questions

1

Which of the GSM services are the basis for data transmission?

bearer services,
teleservices,
supplementary services.

2

What is the maximum data rate for GSM data transmission?

$2.4 \ \rm kbit/s$.
$7.8 \ \rm kbit/s$.
$9.6 \ \rm kbit/s$.

3

Which statements are true for teleservices?

Tele services are end-to-end services.
A distinction is made between synchronous and asynchronous tele services.
Examples are the telephone, fax and SMS services.

4

Which supplementary services originate from GSM phase 2?

"Call Forwarding",
"Call Waiting",
"General Packet Radio Service"  $\rm (GPRS)$,
"Conference Call"  $\rm (CONF)$.

5

What technology is used in  "High Speed Circuit-Switched Data"  $\rm (HSCSD)$?

Packet switching,
circuit switching.


Solution

(1)  Correct is the  proposed solution 1:

  • Bearer services form the basis for data transmission.
  • They provide the technical means to transport data in a secured manner.


(2)  Correct is the  proposed solution 3:

  • The maximum data rate for GSM data transmission is  $9.6 \rm kbit/s$.
  • There are synchronous and asynchronous as well as circuit-switched and packet-switched data transmission.


(3)  Correct are the  proposed solutions 1 and 3:

  • Proposition 2 is incorrect:
  • The terms  "synchronous"  and  "asynchronous"  play a role only in connection with bearer services.


(4)  Correct are the  proposed solutions 2 and 4:

  • In contrast,  "call forwarding"  belongs to GSM phase 1 and  "General Packet Radio Service"  $\rm (GPRS)$  to phase 2+.


(5)  Correct is the  proposed solution 2:

  • "High Speed Circuit-Switched Data"  $\rm (HSCSD)$  was introduced as a circuit-switched transmission technology.
  • In contrast,  "General Packet Radio Service"  $\rm (GPRS)$  operates as packet-switched and  "Enhanced Data Rate for GSM Evolution"  $\rm (EDGE)$  can be described as circuit-switched data service.