5
Third-Generation Cellular: UMTS
∗
Dramatic developments have been taking place in the mobile radio area all
over the world during the last couple of decades. Mobile communications is
one of the fastest growing markets in the telecommunications area. According
to projections, there will be a linear increase in the number of subscribers to
the major GSM networks operated in Europe by the end of the decade.
The political environment in Europe is the main reason for the rapid devel-
opment. Without a free exchange of information, the concept of an internal
market striving for a free flow of goods between EU states would be inconceiv-
able. This was the line of thinking behind the liberalization and deregulation
of the telecommunications industry, which promoted and accelerated compe-
tition and opened up the markets.
Another reason for this rapid development is the advances being made
in the microelectronics, microprocessor and transmission technology areas.
These advances are enabling the use of ever smaller terminal equipment, with
computing power previously only possible with mainframes, and with low
power consumption—factors that have improved customer acceptance.
In Europe the development of uniform standards, the introduction of Euro-
pean-wide radio systems and the participation of industry in the standardiza-
tion process through the establishment of ETSI have further contributed to
the widespread success of mobile communications.
The chronological development of different kinds of mobile radio networks
which conform to different user needs is presented in Figure 1.2 [23].
The systems that fall into the category of first-generation mobile commu-
nications systems in which mobility is only ensured within a specific network
area are the different analogue cellular systems (e.g., C-Netz, NMT), cordless
systems (CT1/CT2) and various national paging systems.
The second generation includes the digital systems such as GSM, DCS
1800, USDC, PDC, IS-95 and ERMES, which underwent further development

ISDN
S-PCN
DECT
Networks
Access
UIM
UIM
Examples:
GSM
BSS
TE
TE
Fixed
Fixed
Mobile
TE
Mobile
TE
Examples:
GSM NSS + IN
ISDN/IN-based
B-ISDN + IN-based
TCP/IP-based
B-ISDN + TINA-based
Access Network Domain
Figure 5.1: Global multimedia mobility architecture
tions (ETSI/DECT, see Chapter 9, and the Personal Handyphone System,
PHS, see Chapter 11), local broadband communications (ETSI/HIPERLAN
1, see Section 13.1, IEEE 802.11, see Section 13.9), wireless ATM systems
(ETSI/BRAN, see Section 12.1.5), mobile personal satellite radio (IRIDIUM,

stations.
• Operation in non-synchronous base station subsystems.
• Advanced mobility characteristics (UPT, see Chapter 15; roaming, han-
dover, etc.).
• Flexible frequency management.
• Flexible management of radio resources.
5.1 UMTS (Universal Mobile
Telecommunications System)
In Europe work continues to be carried out on the development of a third-
generation mobile radio system called UMTS (Universal Mobile Telecommuni-
cations System) in the EU programmes RACE (1989–1994) (Research and De-
velopment in Advanced Communications Technologies in Europe) and ACTS
(1995–1998) (Advanced Communication Technologies and Services) in coop-
eration with ETSI. Work on UMTS is also being done in COST (European
Cooperation in the Field of Scientific and Technical Research) projects [20].
The technical subcommittee (STC) SMG 5 at ETSI has been given the
responsibility for producing the UMTS standard. Other SMG subcommit-
tees that are currently still working on the GSM 2+ standard will eventually
324 5 Third-Generation Cellular: UMTS
become involved in the standardization of UMTS, e.g., SMG 2. SMG 5 will
then take over the creation of the UMTS standard and the coordination of
the standardization activities. There is also the UMTS Forum, comprising
the European signatories to the UMTS–Memorandum of Understanding of
the Introduction of UMTS defined in 1996.
The main tasks of SMG 5 are [2, 15]:
• Study and definition of services, system architecture, the air interface
and the network interfaces for UMTS.
• Generation of basic technical documentation for UMTS.
• Coordination of ETSI and of SMG regarding UMTS.
• Cooperation and coordination with the ITU for the definition of a world-

5.1 UMTS (Universal Mobile Telecommunications System) 325
300-500 MHz
UMTS Core Band
2110 MHz 2170 2200 MHz2025 MHz2000
+ 20 MHz
+ 15 MHz
Sat Sat
Year 2002: 2x30 MHz
Year 2005: 2x60 MHz
Year 2008: approx. 300
to 500 MHz
1900 MHz
e.g., Downlink
Licensed Licensed/Unlicensed Licensed
e.g., Uplink 60 MHz
95 MHz
Figure 5.2: UMTS frequency spectra, UMTS Forum’s perception of timetable for
development
MSS
Reg.2
MSS
Reg.2
Europe
Japan
USA
ITU/RR
MSS
MSS
MSS
MSS

by Ericsson to ITU-R is capable of providing wideband services compatible
to GSM 2+.
The main driving force towards UMTS at present comes from manufactur-
ers aiming to introduce new products into the market and operators aiming to
get under the label UMTS access to more bandwidth for voice services only.
Mobile data was still only a few percent of business in 1998. The European
Commission has issued guidelines for the licensing of UMTS bands to opera-
tors demanding that 50 % of the services offered should be data services for
multimedia applications.
The demand for more bandwidth can of course easily be covered by assign-
ing UMTS frequency bands to be used by GSM networks, and does not need
the introduction of a new air interface.
5.2 FPLMTS (Future Public Land Mobile
Telephone System); IMT 2000 (International
Mobile Communications at 2000 MHz)
In 1985 the CCIR (see Annex B.1.2) set up a working group, the Task Group
8/1 (previously IWP 8/13), for the purpose of specifiying all the requirements
and system parameters for a future public land mobile telecommunication
system (FPLMTS). The following requirements for an FPLMTS were drawn
up by the working group [5, 13, 19]:
• Small, lightweight handheld equipment.
• Worldwide use of terminal equipment, i.e., uniform frequencies world-
wide.
• Integration of different mobile radio systems and international roaming.
• Integration into the fixed telephone networks (ISDN compatibility).
• Integration of mobile satellite radio.
• Use of terminal equipment on land, in the air and at sea.
As with the UMTS, the aim with the FPLMTS is to integrate all existing
services (mobile telephony, cordless telephony, paging, trunked radio, etc.)
into one service. Many of the aspects of FPLMTS are the same as those of

programme. These UMTS-supported services are described below.
5.3.1 Carrier Services
UMTS should be able to support ISDN as well as broadband ISDN bearer
services. The following services are to be integrated [10]:
• Circuit-switched services:
– Transparent 64, 2·64, 384, 1536 and 1920 kbit/s with user data
rates of 8, 16 and 32 kbit/s
– Voice transmission
– 3.1, 5 and 7 kHz audio transmission
– Alternative voice or transparent data transmission with user data
rates of 8, 16, 32 and 64 kbit/s
328 5 Third-Generation Cellular: UMTS
• Packet-switched services:
– Virtual calls and permanent virtual channels
– Connectionless ISDN
– User signalling
Broadband (B) ISDN services with a transmission rate of 2 Mbit/s (so-
called wideband services) are also to be offered by UMTS to mobile users.
According to CCITT, these services will be classified as interactive or distri-
bution services.
Interactive services fall into the category of conversational services, message
services or interrogation services. Conversational services are implemented
through end-to-end connections, which can be either symmetrical bidirec-
tional, asymmetrical bidirectional or unidirectional. Message services offer
communication between users that is not time transparent. Interrogation ser-
vices are used for the inquiry and receipt of centrally stored data.
With distribution services information can be transmitted continuously
from one central location to any number of users, with the users unable to
influence the start or the end of a transmission. Another distribution service
offers users the possibility of influencing the start of the information trans-

sion
• Paging
• Broadcast services
• Database inquiries
• Data transmission
• Directory services (e.g.,
telephone book)
• Emergency call broadcasts
• Short-message services:
– Initiated by user
– Terminated by user
– Voice messages
– Facsimile
– Electronic mail
• Teleaction services (e.g.,
remote control)
• Mobility services (e.g.,
navigation or localization)
• Electronic mail
• Emergency calls
• Teleshopping
• Video monitoring
• Voice messages
3. The services with the largest need for bandwidth are multimedia (MM)
and interactive multimedia (IMM), such as data, graphics, images, audio
and video, and combinations thereof. With UMTS it should be possible
to use more than one of these media at the same time. Multimedia allows
the transmission of more than one type of information, e.g., video and
audio information. No further specifications exist yet for this service
[10].

independent option of selecting between a higher bandwidth for a max-
imum quality of service or a lower bandwidth for more favourable costs.
5.3.5 Service Parameters
A service is characterized by different parameters, some of the most important
being:
• Net bit rate
• Symmetry of a service
• Usage level
• Coding factor
• Maximum bit-error ratio based on channel decoding
• Maximum delay allowed in data transmission
The net bit rate is the product of the average number of bits that have to
be transmitted within a certain period of time.
The delay parameter describes how long a waiting time is allowed in the
transmission of these bits. For example, a voice service requires a small delay
whereas a packet-data transmission has minimal requirements for the delay
times of individual packets. However, data transfer requires a considerably
lower bit-error ratio than a voice service, because the redundancy of the voice
codec can be fully utilized. A higher coding factor is needed for achieving a
5.3 Services for UMTS and IMT 2000 331
Table 5.1: Quality of service parameters
Service Call Data rate Residual bit- Delay [ms]
duration [kbit/s] error ratio
Telephony
– Voice 2 min 8−32 10
−4
40
– Teleconferencing 1 h 32−128 10
−4
40

Teleshopping tbd 2.4−768 10
−6
90
Electronic mail tbd 2.4−2000 10
−6
200
Message dist. cl 2.4−2000 10
−6
300
Tele-action services tbd 1.2−64 10
−6
100–200
tbd to be defined cl connectionless
lower bit-error ratio in order to protect data during transmission over a radio
channel.
The usage level parameter describes how often a connection is being used
to transmit data. For example, the usage level of a voice service is less than
0.5 because a user is generally either listening or speaking.
A service is also defined by its symmetry. This value determines which
bandwidth is required for a connection in one or the other direction. The voice
service is an example of a symmetrical service, because the same bandwidth is
used for both speaking and listening. Internet browsing (e.g., world wide web,
WWW) is a typical example of an asymmetrical service, because it requires
considerably less bandwidth for requesting than for receiving data. Table 5.1
lists the characteristics of some of the services.
5.3.6 Service-Specific Traffic Load
The effective service bandwidth can be calculated from the data of the ser-
vice parameters net bit rate, symmetry and coding factor [12]. The service
bandwidth describes the bandwidth used to provide a particular service.
The traffic generated by the use of a service is calculated by taking the

(5.2)
An ETE therefore corresponds to an Erlang of voice service with a transmis-
sion bandwidth of 16 kbit/s. This equation was used to produce an example of
the traffic load for voice telephony, video telephony and the facsimile service.
The throughput represents the speed at which the user data is transmit-
ted. This data quantity is increased by a constant factor through the coding
used for error detection and correction. Finally consideration must be given
to the form of symmetry. For example, with the telephony services data is
transmitted in both directions, whereas with the facsimile service it is mainly
in one direction.
5.3.6.1 Voice Telephony
Voice telephony is a symmetrical service with a usage level of 0.5 or less. The
net bit rate of the voice codec is 16 kbit/s. Since the requirements for bit
error ratio are low, a coding factor of 1.75 is sufficient. For the average call
duration 120 s is assumed. This equates to an effective service bandwidth of
56 kbit/s and an effective call duration of 60 s (see Table 5.2).
The estimated values for penetration D and for the frequency of calls during
a busy hour produce the ETE/user values shown in Table 5.3 for the voice
service in different communications environments (see Section 5.5.1).
5.3.6.2 Video Telephony
Video telephony is a symmetric service and has a usage level of one, i.e.,
transmission is always in both directions of a connection. The effective service
bandwidth for the video telephony service is 384 kbit/s and the effective call
duration 2 min (see Table 5.2).
The estimated values for the penetration D and for the BHCA produce the
ETE/user values in Table 5.4 for different communications environments.
5.3 Services for UMTS and IMT 2000 333
Table 5.2: Service bandwidth and effective call duration of some services
Voice telephony Video telephony Fax service
Throughput [kbit/s] 16 64 64

Aircraft 0.04 0.5 4.75 ·10
−3
Local high bit rate 0.13 1.0 2.97 ·10
−2
5.3.6.3 Facsimile
A throughput of 64 kbit/s is assumed for the facsimile service, which corre-
sponds to the transmission rate of the facsimile service currently being offered
by ISDN. The facsimile service is an asymmetrical service with a coding fac-
tor of 3. This produces an effective service bandwidth of 211.2 kbit/s. The
effective call duration is 156 s (see Table 5.2).
The estimated values for penetration D and for BHCA produce the
ETE/user values in Table 5.5 for different communications environments.
5.3.6.4 Resultant Overall Traffic Loads
The procedures presented in the sections above can be used to calculate the
traffic generated by a user in each of the services listed. Table 5.6 gives the
total traffic generated by a user in the different communications environments
334 5 Third-Generation Cellular: UMTS
Table 5.5: Calculation of traffic load for facsimile services
Operating environment D BHCA per user ETEs per user
Business use indoors 0.3 0.06 2.94 ·10
−3
Residential area 0.15 0.03 7.35 ·10
−4
City centre, in vehicle 0.1 0.002 3.27 ·10
−5
City centre, pedestrian outdoors 0.1 0.002 3.27 ·10
−5
Aircraft 0.15 0.002 4.90 ·10
−6
Local high bit rate 0.3 0.06 2.94 ·10

−3
730 6.95
pedestrian
Aircraft 7.91 · 10
−3
9.49 · 10
−3
0.24 2.28 · 10
−3
Local high bit rate 4.10 · 10
−2
4.92 · 10
−2
108000 8.85 · 10
3
(see Section 5.5.1). If a specific user density is assumed for each communica-
tions environment [10] then it is always possible to arrive at a value for the
traffic load.
This traffic load describes in ETEs the traffic originating from an area.
The requirement for frequency spectrum can be calculated if an assumption
is made on the efficiency of the radio interface (see Section 5.4).
5.4 Frequency Spectrum for UMTS
This section presents the UMTS Forum assessments on the frequency spec-
trum required for UMTS [12]. They are based on estimates of market pene-
tration, future user density, service characteristics and characteristics of the
radio interface.
In determining the bandwidth needs the UMTS Forum makes its assump-
tions based on the breakdown of different categories of service shown in Fig-
ure 5.4. In addition, assumptions are made on anticipated user numbers in
relationship to the communications environment. The figures for the year

City, auto 2 780
Rural areas (total) 36
rical service with the same transmission rates on the uplink and the down-
link. Simple message services are those services that are similar to the SMS
(Short-Message Service) in GSM. The asymmetric multimedia services (MM)
represent typical Internet services (WWW using the http protocol), whereas
the interactive multimedia service represents a symmetrical connection such
as is required for video conferencing.
Together with the ratio of the average number of active users to the overall
number, measured during the busy hour (see Table 5.9), the bandwidth re-
quirements for UMTS can be calculated from the information supplied in the
service characteristics and user density (see Table 5.10).
The projected bandwidth requirements for each service for the years 2005
and 2010 are presented in Figure 5.5.
The maximum requirement for bandwidth projected for the year 2010 is
554 MHz for traffic bands and 28 MHz for guard bands. The basic standards
for UMTS have been completed in March 1999, and UMTS itself is expected
to be introduced in about 2003. The UMTS Forum has a preference for
the frequencies given in Figure 5.2, staggered timewise as shown, with bands
336 5 Third-Generation Cellular: UMTS
Table 5.8: Overview of service characteristics
Service Net Coding Symmetry Eff. call Service
rate factor duration bandwidth
[kbit/s] [s] [kbit/s]
High interactive MM 128 2 1/1 144 256/256
High data rate MM 2000 2 0.005/1 53 20/4000
Med. data rate MM 384 2 0.0026/1 14 20/768
Packet-sw. data 14 3 1/1 156 43/43
Simple mess. serv. 14 2 1/1 30 28/28
Voice 16 1.75 1/1 60 28/28