Exercise 3.2: GSM Services

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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

Solution

(1)  Correct is the proposed solution 1:

• Carrier 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 proposed solutions 1 and 3:

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

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

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

(5)  Correct is the proposed solution 2:

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