Chapter
6
Evolution of GSM and cdmaOne to
3G Systems
6.1 Introduction
The previous chapters have concentrated on the two leading second generation (2G) cellular
systems: GSM and IS-95. These systems are deployed in many parts of the world and will
continue to operate and evolve during the next decade as third generation (3G) systems are
rolled out. We may expect that the new 3G systems will be harmonised with their evolved
2G counterparts, and that slowly 2G spectra will be refarmed to provide extra 3G spectra.
No 3G systems are currently deployed, although trials are in progress. As a consequence,
this chapter, which deals with systems that are about to be deployed, is treated in a qual-
itative manner, describing how they will work rather than quantifying their performances.
Before getting into detail, let us briefly review how cellular communications arrived at to-
day’s position.
6.1.1 The generation game
There is no doubt that there was pent-up demand for public mobile telephony networks,
and when they arrived in the 1980s as the so-called first generation (1G) analogue cellular
networks, they grew at phenomenal rates. These networks initially offered only telephony,
but the un-tethering of people from their fixed phones meant that they and businesses could
operate in completely new ways. The Europeans identified in the early 1980s the need for a
second generation (2G) cellular system that would be totally digital. This 2G system became
GSM, and a brief history of GSM has already been provided in Section 2.1. The Europeans
have a long view in cellular radio and in 1988 they launched their RACE 1043 project with
404
GSM, cdmaOne and 3G Systems. Raymond Steele, Chin-Chun Lee and Peter Gould
Copyright © 2001 John Wiley & Sons Ltd
Print ISBN 0-471-49185-3 Electronic ISBN 0-470-84167-2
6.1. INTRODUCTION
405
the aim of identifying the services and technologies for an advanced third generation (3G)

part of its 3G spectrum for PCS licenses, and allowed GSM to enter the United States in
the form of PCS1900. This auctioning of the 3G spectrum meant that there were significant
advantages if existing 2G networks could evolve into 3G ones, preferably in a seamless
manner.
A big factor, not just in the United States, but in the world, was the advent of IS-95 [7–11].
It arrived late compared with GSM, and some engineers argued that it was a 2.5G system.
It had to fight to be born because of the lack of spectrum, and the quasi-religious attitudes
406
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
of engineers towards methods of multiple access. The meagre spectrum of 1.25 MHz at the
top of the AMPS band was just about adequate for cellular CDMA, which was just as well
because that was all there was available. CDMA entered the cellular world with a host of
technical problems, not made easier as the transceivers from day one had to be dual-mode
with AMPS. Its advocates were clear in that CDMA has a high spectral efficiency and is
well suited to the 3G multiservice environment. The real significance of IS-95 is that it won
the technical argument in that the UMTS and the Japanese Association of Radio Industries
and Businesses (ARIB) proposals have CDMA radio interfaces, albeit of wider bandwidth
systems as more bandwidth is available for 3G networks. We therefore agree that IS-95 is a
2.5G system and its evolution to 3G should be smooth. This is not so for 2G TDMA systems
which will need to migrate to 3G CDMA ones. However, as we will show in Section 6.2,
GSM with its TDMA is able to evolve closely to 3G without picking up the CDMA card.
Nevertheless there is an evolutionary route from GSM Phase 2+ to UMTS as discussed in
Section 6.2
The TG8/1 Committee discarded the unwieldy FPLMTS name for its 3G system, and
replaced it with international mobile telecommunications for the year 2000, or simply IMT-
2000. It then abandoned all hope of the difficult political objective of a single standard,
and has instead opted for a family of standards. Each member of the family had to be
able to meet a minimum specification. Sixteen proposals were accepted, ten for terrestrial
3G networks, and six for MSSs. The majority of the proposals advocated CDMA as the
multiple access method. A degree of harmonisation between the proposals ensued, and at

segment is shown in Table 6.1
Part of Segment 1 is currently used for DECT in Europe, and is also used for PHS, PCS
and DECT in other parts of the world. Segment 2 is used at present for PCS and PHS in the
United States and Japan, respectively. Segments 3 and 6 form 60 MHz frequency division
duplex (FDD) bands. Mobile satellite services (MSS) are in Segments 4 and 7, providing
30 MHz FDD bands. Segment 4 supports the earth-to-space links; while segment 7 provides
the space-to-earth links. The 1980–1990 MHz band in Segment 4 is currently used for PCS
in the United States. Segments 1, 2 and 5 are unpaired and are suitable for time division
duplex (TDD) operation. Segment 5 may be used in the United States for earth-to-space
MSS services.
6.2 Evolution of GSM
The GSM system was initially designed to carry speech, as well as low speed data. Much
has already been discussed regarding speech, so we will concentrate here on data. The user
data rate over the radio interface using a single physical channel, i.e. a single timeslot per
Table 6.1 : IMT-2000 spectrum and its segments (MSS stands for mobile satellite services).
Segment Frequency Comment
number band (MHz)
1 1885–1900 Unpaired
2 1900–1920 Unpaired
3 1920–1980 Paired with 6
4 1980–2010 MSS paired with 7
5 2010–2025 Unpaired
6 2110–2170 Paired with 3
7 2170–2200 MSS paired with 4
408
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
1700 1750 1800 1850 1900 1950 2000 2050 2100 22002150
IMT-2000 IMT-2000
MSS
MSS

packet-orientated connections on the radio interface (and within the network) whereby a
user is assigned one, or a number of traffic channels only when a transfer of information
is required [13]. The channel is relinquished once the transmission is completed. In the
following sections we will describe these two services in more detail.
6.2. EVOLUTION OF GSM
409
The second approach to increasing the user data rate by employing a higher level modu-
lation scheme is currently being studied under the Enhanced Data Rates for GSM Evolution
(EDGE) project [14]. The basic principle behind EDGE is that the modulation scheme used
on the GSM radio interface should be chosen on the basis of the quality of the radio link. A
higher level modulation scheme is preferred when the link quality is ‘good’, but the system
reverts to a lower level modulation scheme when the link quality becomes ‘poor’. At the
time of writing it appears that EDGE will use the existing Gaussian minimum shift keying
(GMSK) modulation scheme in poor quality channels and eight-level phase shift keying (8-
PSK) in good quality channels. EDGE will also include link adaption functions to allow the
MS and BS to assess the link quality and switch between the different types of modulation
as necessary.
Once developed, the EDGE technology will enhance the range of services offered by
GSM. The initial version of the EDGE technology (Phase 1) will be used to enhance the
GPRS and HSCSD services, leading to enhanced GPRS (EGPRS) and enhanced circuit-
switched data (ECSD). In later releases of EDGE (Phase 2 and beyond) further services
will be introduced which utilise the different modulation schemes [14].
In addition to the developments described above, GSM Phase 2+ contains two other im-
portant enhancements that have a significant impact on the technology from a radio point of
view. In 1993 the European railways, in the form of the Union Internationale des Chemins
de Fer (UIC), chose the GSM technology as the basis of all their future mobile radio com-
munication systems [15]. This led to the introduction of a number of advanced speech call
items (ASCI) which provide the additional functionality required for railways and other
private mobile radio (PMR) environments. The three key elements of ASCI are the voice
broadcast service (VBS), the voice group call service (VGCS) and the enhanced multi-level

and the radio interface. Additional functionality is also included at the radio resource man-
agement level to handle the new situation where a number of different traffic channels are
associated with the same connection. For example, when an HSCSD user is handed over
between two cells, there must be a mechanism to ensure that sufficient traffic channels are
available in the new cell before the handover occurs. An HSCSD connection is, however,
limited to a single 64 kb/s circuit on the A interface.
On call set-up the MS provides information to the network which defines the nature of the
HSCSD connection. The multislot class of the MS is used by the network to determine the
maximum number of timeslots that may be accessed by the MS, and the amount of time that
must be allowed between timeslots, e.g. for the purposes of neighbour cell measurements.
This information is used to define the MS’s capabilities for both the HSCSD and GPRS
services. The multislot classes are listed in Table 6.2 along with their associated parameters
[17].
Multislot MSs can be either type 1 or type 2 and this information is shown in the right-
hand column of Table 6.2. Type 2 MSs are required to be able to transmit and receive
simultaneously, whereas type 1 MSs are not. The ‘Rx’ and ‘Tx’ columns give the maxi-
mum number of receive and transmit timeslots that the MS may occupy per TDMA frame,
respectively. The ‘Sum’ column gives the total number of transmit and receive timeslots
the MS may access per TDMA frame. For example, for multislot class 12, ‘Sum’ is 5
which means that the maximum number of transmit and receive slots cannot exceed 5. So
if we have 3 received slots, then we cannot have more than 2 transmit slots in one TDMA
frame. The T
ta
parameter represents the time required for the MS to make a neighbour cell
measurement prior to an up-link transmission. This parameter is not applicable to type 2
6.2. EVOLUTION OF GSM
411
MSs because they are capable of making measurements and transmitting simultaneously.
When the MS is not required to make measurements on neighbouring cells, the T
tb

Many services do not require a continuous bi-directional flow of user data across the radio
interface. To illustrate this, consider the example of a user browsing the Worldwide Web
(WWW) on her lap-top computer using a dial-up connection via a cellular network. Once
a page of information has been downloaded, there will be a pause in the information flow
between the MS and the network as the user reads the information and before more infor-
mation is requested. Using circuit-switched connections for ‘bursty’ services of this nature
represents an inefficient use of the radio resources because a user will continue to occupy a
radio channel for the duration of a call (or browsing session) even though this channel may
only be utilised for a small fraction of the time. Inefficiencies of this type can be overcome
by carrying these services using packet-orientated connections.
The GSM system was initially designed to support only circuit-switched connections at
the radio interface level with user data rates of up to 9.6 kb/s. However, the Phase 2+
412
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
Table 6.2 : The MS multislot classes.
Multislot Maximum number of slots Minimum number of slots Type
class Rx Tx Sum T
ta
T
tb
T
ra
T
rb
111 2 3242 1
221 3 3231 1
322 3 3231 1
431 4 3131 1
522 4 3131 1
632 4 3131 1

=
(
1 if frequency hopping is used or there is a change from Rx to Tx
0 if frequency hopping is not used and there is no change from Rx to Tx
c
=
(
1 if frequency hopping is used or there is a change from Tx to Rx
0 if frequency hopping is not used and there is no change from Tx to Rx
6.2. EVOLUTION OF GSM
413
specifications now include provision for the support of a packet-orientated service known
as the general packet radio service (GPRS) [13, 18–20]. GPRS attempts to optimise the
network and radio resources, and strict separation between the radio subsystem and the
network subsystem is maintained, although the network subsystem is compatible with the
other GSM radio access procedures. Consequently, the GSM MSC is unaffected. The
allocation of a GPRS radio channel is flexible, ranging from one to eight radio interface
timeslots in a TDMA frame. Up-link and down-link timeslots are allocated separately. The
radio interface resources are able to be shared dynamically between circuit switched and
packet services as a function of service load and operator preference. Bit rates vary from
9 kb/s to more than 150 kb/s per user. GPRS can interwork with IP and X.25 networks.
Point-to-point and multipoint services are also supported, as well as short message services
(SMS).
GPRS is able to accommodate both intermittent, bursty data transfers as well as large
continuous data transmissions. Reservation times are typically from 0.5 s to 1 s. Three
MS modes are supported, each having a different arrangement with circuit switched GSM
services. In this section we provide an overview of the GPRS technology and examine its
impact on the GSM radio interface.
6.2.2.1 The GPRS logical architecture
Figure 6.2 is a block diagram showing the architecture of a GSM network that supports

GcGrGs
GGSN
Gp
SGSN
Other GSM networks
D
SMS-GMSC
SMS-IWMSC
Gd
E
C
EIR
Gf
Gn
SM-SC
Gi
PDN
Signalling Interface
Signalling and Data
Transfer Interface
that support GPRS
Figure 6.2: The GPRS network architecture.
an HLR (Gr interface), an EIR (Gf interface) and a short message service gateway MSC
(SMS-GMSC) and interworking MSC (SMS-IWMSC) (Gd interface). The SMS-GMSC
and SMS-IWMSC allow the GSM short message service (SMS) to be carried on the GPRS
channels instead of by the SDCCH and the SACCH. The GPRS support nodes (i.e. the
GGSNs and SGSNs) of a PLMN are interconnected using an Internet protocol (IP) based
backbone network.
6.2.2.2 GPRS transmission plane
This is a layered protocol structure enabling user information transfer and associated con-

allow a user to use the services and facilities the network provides. A user may make an
access attempt, or the user may be paged. The fixed network interface, Gi, may support, at
the discretion of the PLMN operator, multiple access protocols to external networks such
as X.25 and IP.
Anonymous access The idea of anonymous access has also been introduced into GPRS
whereby an MS can access the network without being authenticated and without air-interface
encryption being required. There is also no requirement for the MS to supply its IMSI or
IMEI, although there is provision for the network to request these. One example of an ap-
plication that could make use of this facility is automatic road-tolling, whereby a road user
could use a pre-paid card, inserted into a GSM terminal, automatically to make payment as
she approaches a toll booth.
Packet routing and transfer functions A route consists of an originating network node,
and if required, relay nodes, and finally a destination node. Routing is the transmission
of messages within and between PLMNs. A node forwards data received to the next node
using the relay function. The routing function determines the network GPRS support node
416
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
Application
IP/X.25
SNDCP
LLC
GSM RF
MAC
RLC
MS
Um
Relay
RLC
MAC
GSM RF

(GSN) where the message is sent using the destination address in the message. The routing
function also selects the transmission path to the next GSN along the route. Address transla-
tion is needed to convert one address to another when packets are routed between PLMNs.
Encapsulation is the addition of address and control information to the PDU for routing
within and between PLMNs. Encapsulation, and its reverse, are performed between the
GGSN nodes of PLMNs, and between the SGSN and an MS. The tunnelling function (see
the transmission plane) is the transfer of encapsulated PDUs within and between PLMNs
from where they are encapsulated to where they are decapsulated. There is a compression
function that removes as much overhead information as possible, prior to radio transmis-
sion. The ciphering function provides confidentiality of a user’s data, while the domain
name server function is a standard IP function that resolves any name for GSNs and other
6.2. EVOLUTION OF GSM
417
GPRS nodes within the GPRS backbone networks.
GPRS mobility management and the MS states Mobility management describes the
processes in the mobile radio system that are associated with tracking the movements of
subscribers as they travel around a network. The non-GPRS GSM system uses location
areas and location update procedures to ensure that it always knows the whereabouts of its
MSs. The GPRS uses a similar approach, but instead of using the existing location areas
(LAs) it uses routing areas (RAs). If an MS detects that it has entered a new RA it will
submit a routing area update request message to the network, which if successful, will be
acknowledged with a routing area update accept message. The decision as to whether a
GPRS-equipped MS should perform the RA update procedure as it moves between RAs
will depend on the GPRS state of the MS.
A GPRS-equipped MS may be in any one of three different states for the purposes of
mobility management. In the idle state the MS is ‘not reachable’ as far as the GPRS is
concerned. If an MS is in the idle state, the network does not hold any information regarding
the location of the MS, and hence the MS cannot be paged. It also means that the MS does
not need to perform any RA updates as it moves around the network. MSs in the idle state
cannot access the packet data services without first performing a procedure known as GPRS

The radio interface functions for GPRS are the medium access control (MAC) and radio
link control (RLC) that operate above the physical layer. The MAC function arbitrates be-
tween MSs attempting to transmit at the same time. It is therefore concerned with collision
avoidance, detection, and recovery following a collision. The MAC function may let a sin-
gle MS use several physical channels simultaneously. The multiplexing of data and control
signalling on both links is affected by the MAC function, as well as by priority scheduling.
The GPRS RLC function supports the transfer of logical link control layer PDUs (LLC-
PDU) between the LLC and MAC entities, the segmentation and reassembly of LLC-PDUs
into RLC data blocks, and backward error correction for the retransmission of uncorrectable
code words.
Packet data logical channels Although circuit switched and GPRS services use the same
physical channels, they have different logical channels. The physical channel dedicated to
packet data is called a packet data channel (PDCH). The logical channels for common con-
trol signalling for packet data are carried by the packet common control channel (PCCCH),
and there is also the packet random access channel (PRACH), an up-link-only channel used
by MSs to initiate data or signalling packet transmission. The other PCCCHs are all down-
link ones. There is the packet paging channel (PPCH) that uses paging groups of MSs
to enable discontinuous reception (DRX) to be used. PPCH can be used for both circuit
switched and packet services. The packet access grant channel (PAGCH) identifies the re-
source assignment to be used by an MS prior to packet transfer, while the packet notification
channel (PNCH) provides notification to a group of MSs that a PTM-M packet transfer is
imminent. The packet broadcast control channel (PBCCH) informs the MSs of packet data
specific information. This information may also be transmitted on the BCCH if a PBCCH
has not been allocated.
The packet data traffic channel (PDTCH) is allocated for data transmissions. It is tem-
porarily allocated to an MS (or a group of MSs in the PTM-M case). An MS may be
6.2. EVOLUTION OF GSM
419
assigned multiple PDTCHs.
There are also packet dedicated control channels. The packet associated control channel

CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
the circuit-switched connection. However, in this example there is no requirement for the
GPRS to be deactivated for the particular MS. Class C MSs do not support any simultaneous
use of circuit-switched and packet-based services. A Class C MS can be viewed as operating
in two distinct modes, the GPRS mode and the circuit-switched mode, and it can only be
in one mode at a particular time. For example, if the class C MS is in GPRS mode (i.e. it
is engaged in a packet-based data transfer) and a circuit-switched call arrives at the PLMN
for this particular MS, then the MS will be considered ‘not reachable’ as far as the circuit-
switched call is concerned. It should be noted that the GPRS class of an MS and its multislot
class (see Table 6.2) are separate parameters and there is no direct correlation between the
two.
6.2.2.6 The GPRS quality-of-service
There are four different quality-of-service (QoS) profiles supported in GPRS and these are
dependent on the type of service. For example, an email transaction can tolerate greater de-
lays than, say, an interactive video service, and the QoS profile will be chosen appropriately
in each case. The MS and the network will agree on a particular QoS profile during the
initial service negotiation stages and, as far as possible, the network will attempt to deliver
this QoS to the MS. The QoS service profile is made up of a number of factors, including
the delay class (i.e. the average packet transmission delay), the precedence class (i.e. the
priority value attached to the packets in the event of packet erasure being required as a re-
sult of network congestion), the reliability class (i.e. the probability of errors in the received
data packet), and the peak and average throughput class (i.e. the peak and average rates at
which data are transferred through the network, respectively).
6.2.3 The enhanced data rates for GSM evolution (EDGE)
The driving force behind EDGE is to improve the data rates of GSM by means of enhanc-
ing the modulation methods [14, 21]; specifically, to increase the data rate transmission
per radio timeslot compared with GMSK modulation. Different types of enhanced modu-
lation methods have been considered starting with quaternary offset quadrature amplitude
modulation (Q-O-QAM) and binary offset quadrature amplitude modulation (B-O-QAM),
and ending with 8-level phase shift keying (8-PSK). Although the initial drivers were to

of GMSK. Since the symbol rate is 271 ksymbols/s then the gross bit rates per slot (includes
overhead) is 22.8 and 69.2 kb/s for GMSK and 8-PSK, respectively. The pulse shape for
8-PSK is such that the 8-PSK spectrum fits within the GMSK spectrum mask. The normal
burst format for EDGE is the same as for GSM, except the two sets of 58 symbols now have
three bits per symbol.
Packet switched transmission The EDGE concept has both packet switched and circuit
switched modes. Indeed, EDGE is more like the grand evolutionary plan of GSM that in-
cludes both GPRS and HSCSD. The enhanced GPRS (EGPRS) differs from GPRS because
with multilevel modulation the channel coding must be improved because it is more vul-
nerable to interference and noise. Accordingly a link adaption scheme regularly estimates
link quality and selects GMSK or 8-PSK and the appropriate channel coding to provide the
highest user bit rate. At the time of writing various schemes are being considered for stan-
dardisation. The coding rate is determined by the amount of puncturing. The rate per time
slot for GMSK is 11.2, 14.5, 16.7 and 22.8 kb/s for code rates of 0.49, 0.64, 0.73, and 1.0,
respectively. For 8-PSK the rate per time slot is 22.8. 34.3, 41.25, 51.6, 57.35 and 69.2 kb/s
for code rates of 0.33, 0.50, 0.60, 0.75, 0.83 and 1.0, respectively.
The enhanced circuit switched (ECSD) mode has the data interleaved over 22 TDMA
frames. For GMSK modulation the rate per time slot is 3.6, 6, 12 and 14.5 kb/s for a code
422
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
rate of 0.16, 0.26, 0.53 and 0.64, respectively; while for 8-PSK the bit rates have the higher
values of 14.5, 29, 32 and 38.8 kb/s for code rates of 0.42, 0.46, and 0.56, respectively.
For EGPRS when QoS issues are addressed where different factors, such as priority of
packet transmissions, packet delay, packet throughput, maximum and minimum bit rates
that must be handled, and so on, need to be considered, then the maximum bearer rate
should be able to accommodate data rates of 384 kb/s for MS speeds up to 100 km/h and
144 kb/s for an MS travelling at 250 km/h. These rates require a user to make use of multiple
slots per frame if these high bit rates are to be achieved. Fewer slots are required if 8-PSK
is used. Similar comments can be made regarding bearer rates for ECSD. For low bit error
rate transmissions the maximum user bit rate is 57.6 kb/s.

AI Acquisition indicator
AICH Acquisition indication channel
BCH Broadcast control channel
CCPCH Common control physical channels
CPCH Common packet channel
CPICH Common pilot channel
DPCCH Dedicated physical control channel
DPDCH Dedicated physical data channel
DCH Dedicated channel
FACH Forward access channel
FBI Feedback information
FDD Frequency division duplex
GMSC Gateway MSC
GGSN Gateway GPRS support node
I
uCS
Interface between an RNC and an MSC
I
uPS
Interface between an RNC or BSC and an SGSN
I
ur
Interface between RNCs
MAC Medium access control
MSC Mobile switching centre
MUD Multiuser detection
Node B Base station transceiver
OVSF Orthogonal variable spreading factor
P-CCPCH Primary common physical channel
PCH Paging channel

with authentication, home and visitor location registers and equipment identity registers are
essential to support both circuit-switched and packet data networks. Thus, the core network
is architecturally a GSM Phase 2+ core network that is powered up so that it can also handle
the higher volume, higher bit rate, UMTS traffic.
Shown below the core network in Figure 6.5 are two GSM base station subsystems (BSSs)
and two UMTS radio network subsystems (RNSs). The A-interface is between a base sta-
tion controller (BSC) and a mobile switching centre (MSC), and there is an I
uPS
between
a BSC and SGSN, where the subscript uPS signifies a packet switch interface. The A
bis
interface between a BTS and a BSC is also shown.
The UMTS network uses the same core network as GSM, and has interfaces between
the RNC and MSC, SGSN and RNC of I
uCS
,I
uPS
and I
ur
, respectively. The subscript uCS
Table 6.4: GSM and UMTS terminologies of some key entities.
GSM UMTS
Mobile station (MS) User equipment (UE)
Base station transceiver (BTS) Node B
Base station controller (BSC) Radio network controller (RNC)
Base station subsystem (BSS) Radio network subsystem (RNS)
Subscriber identity module (SINM) Universal subscriber identity
module (USIM)
6.3. THE UNIVERSAL MOBILE TELECOMMUNICATION SYSTEM
425

A
I
ubis
A
bis
I
ur
I
uCS
I
uPS
Figure 6.5: UMTS network architecture.
426
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
represents circuit-switched. The equivalent of the A
bis
in UMTS is I
ubis
.
This figure is important because it illustrates the evolutionary path from GSM Phase2+ to
UMTS. We see the different radio interfaces of GSM and UMTS plugging into a common
backbone network.
The physical channels in UMTS transfer information across the radio interface. In the
FDD version of UMTS, a physical channel is defined by its code and carrier frequency,
while in TDD it is in terms of its code, carrier frequency and timeslot. The physical layer
(layer 1) of the protocol stack supports transport channels to the medium access control
(MAC) in layer 2. The MAC layer offers logical layers, e.g. radio link control, to the higher
layers. A logical channel is characterised by the type of information transferred, e.g. it may
be handling control information of data traffic.
Figure 6.6 is a block diagram of a UMTS transmitter at the physical layer. Transport

Higher
Layers
CRC
Attachment
Block
Concatenation/
Segmentation
Channel
Coding
1
st
Interleaving
Radio Frame
Segmentation
Rate
Matching
Traffic Channel
Multiplexing
Physical
Channel
Segmentation
2
nd
Interleaving
Physical
Channel
Mapping
To radio interface
Convolutional Coding
Turbo Coding

f
=
0, not shown in the figure,
and the adjacent carrier would be positioned at
4
f
=
5 MHz. The lightly shaded part of
the figure corresponds to the left-hand ordinate, which is the power measured by a spectral
428
CHAPTER 6. EVOLUTION OF GSM AND CDMAONE TO 3G SYSTEMS
analyser using a bandwidth of 30 KHz. The maximum output power as a function of
4
f
between 2.7 and 3.5 MHz must be less than

14

15
(4
f

2
:
7
)
dBm. The darker shaded
area of the figure is associated with the right-hand ordinate, which is the power measured in
a 1 MHz bandwidth. The value of
4

There are two types of dedicated physical channels. The dedicated physical control chan-
nel (DPCCH) carries physical layer (i.e. layer 1) control information and the dedicated
physical data channel (DPDCH) transports the user traffic, as well as control information
from layer 2 and from higher layers.
The DPCCH contains pilot symbols, transmit power control (TPC) symbols, and a trans-
port format combination indicator (TFCI). The pilot symbols enable the receiver to estimate
the impulse response of the radio channel and to perform coherent detection. They are also
necessary when adaptive antennae are used that have narrow beams. The pilot symbols
constitute a pilot word having a duration of 0.667 ms.
The TPC commands the fast closed-loop power control, and are used on both the up-link
and down-link. TPC symbols are included in every transmitted packet, and they convey
a binary instruction, namely to increase or decrease the transmitted power by a specific
amount.
The TFCI informs the receiver of the instantaneous parameters of the different transport
channels; that is, it tells the receiver of the data rates currently in use. The TFCI also
contains feedback information (FBI) on the up-link which is used to provide a feedback
loop for transmit diversity and selection diversity.
The frame structure, multiplexing arrangement and spreading schemes are different for