i ANALYZING THE SIGNAL FLOW AND RF PLANNING IN GSM NETWORK A PROJECT REPORT Submitted by GOKULAPRIYA P Register No: 14MAE005 in partial fulfillment for the requirement of award of the degree of MASTER OF ENGINEERING in APPLIED ELECTRONICS Department of Electronics and Communication Engineering KUMARAGURU COLLEGEOF TECHNOLOGY (An autonomous institution affiliated to Anna University, Chennai) COIMBATORE-641 049 ANNA UNIVERSITY: CHENNAI 600 025 APRIL 2016
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i
ANALYZING THE SIGNAL FLOW AND
RF PLANNING IN GSM NETWORK
A PROJECT REPORT
Submitted by
GOKULAPRIYA P
Register No: 14MAE005
in partial fulfillment for the requirement of award of the degree
of
MASTER OF ENGINEERING
in
APPLIED ELECTRONICS
Department of Electronics and Communication Engineering
KUMARAGURU COLLEGEOF TECHNOLOGY
(An autonomous institution affiliated to Anna University, Chennai)
COIMBATORE-641 049
ANNA UNIVERSITY: CHENNAI 600 025
APRIL 2016
ii
BONAFIDE CERTIFICATE
Certified that this project report titled “ANALYZING THE SIGNAL FLOW AND RF
PLANNING IN GSM NETWORK” is the bonafide work of GOKULAPRIYA.P
[Reg. No. 14MAE005] who carried out the work under my supervision. Certified further
that to the best of my knowledge the work reported herein does not form part of any other
project or dissertation on the basis of which a degree or award was conferred on an earlier
occasion on this or any other candidate.
HHHH
The candidate with Register No.14MAE005 was examined by us in the project
viva-voice examination held on...............................
INTERNAL EXAMINER EXTERNAL EXAMINER
SIGNATURE
R.KARTHIKEYAN
ASSISTANT PROFESSOR II
PROJECT SUPERVISOR
Department of ECE
Kumaraguru College of Technology
Coimbatore-641 049
SIGNATURE
Dr. A.VASUKI
HEAD OF THE DEPARTMENT
Department of ECE
Kumaraguru College of Technology
Coimbatore-641 049
iii
ACKNOWLEDGEMENT
First, I would like to express my praise and gratitude to the Lord, who has
showered his grace and blessings enabling me to complete this project in an excellent
manner.
I express my sincere thanks to the management of Kumaraguru College of
Technology and Joint Correspondent Shri Shankar Vanavarayar for his kind support
and for providing necessary facilities to carry out the work.
I would like to express my sincere thanks to our beloved Principal
Dr.R.S.Kumar Ph.D., Kumaraguru College of Technology, who encouraged me with
his valuable thoughts.
I would like to thank Dr.A.Vasuki Ph.D., Head of the Department, Electronics
and Communication Engineering, for her kind support and for providing necessary
facilities to carry out the project work.
In particular, I wish to thank with everlasting gratitude to the project
coordinator Ms.S.Umamaheswari M.E.,(Ph.D) Associate Professor, Department of
Electronics and Communication Engineering, throughout the course of this project
work.
I am greatly privileged to express my heartfelt thanks to my project guide
Mr.R.Karthikeyan M.E., Assistant Professor-II, Department of Electronics and
Communication Engineering, for his expert counselling and guidance to make this
project to a great deal of success and I wish to convey my deep sense of gratitude to all
teaching and non-teaching staff of ECE department for their help and cooperation.
Finally, I thank my parents and my family members for giving me the moral
support and abundant blessings in all of my activities and my dear friends who helped
me to endure my difficult times with their unfailing support and warm wishes.
iv
ABSTRACT
In this fast moving electronic world, planning, building and optimisation
process of radio access network is a complex dynamical activity, which requires a lot
of planning effort and time. This project is proposed in the intention of planning a
network with reduced call drops, which seems to be a very big issue among the
subscribers as well as the service providers. It is found that call drops in conventional
networks is less than 0.01% and in mobile network it is greater than 0.1%. As per
TRAI (Telecom Regularity Authority of India), call drops have doubled in last one
year. Call drops jumped two-fold on 2G and 65% on 3G networks. Since continuation
of an active call is a prime importance in cellular system, a new approach has been
proposed to minimize the rate of call drops and increase the quality of the network
both related to customer satisfaction and performance of cellular operator which
enhances the revenue of the company. This approach deals with the design of
increasing the number of carriers in each sector of the BTS (Base Transceiver Station),
which reduces call drops to a greater extent even during peak hours. The optimization
in radio frequency planning is done by increasing the number of carriers in each sector
of the BTS. This planning process is done using a commercial tool called “ATOLL
(Acceptance Test Or Launch Language) TOOL”, which is a 64-bit multi-technology
wireless network design and optimization platform. This includes the coverage,
capacity and frequency planning of RF network, which in turn covers the vast area
effectively. Initially, an effective frequency planning is done for 900MHz BTS (Base
Transceiver Station) sites with a set of BSIC (Base station Identity Code), BCCH
(Broadcast channel), MAL frequency (Mobile Allocation List) and MAIO (Mobile
Allocation Index List).
v
TABLE OF CONTENTS
CHAPTER
NO.
TITLE PAGE NO.
ABSTRACT
iv
LIST OF TABLES viii
LIST OF FIGURES ix
LIST OF ABBREVIATIONS x
1 INTRODUCTION 1
1.1 INTRODUCTION TO MOBILE
COMMUNICATION
1
1.2 DUPLEXING
METHODOLOGY
2
1.2.1 Frequency Division Duplex 2
1.2.2 Time Division Duplex 2
1.3 MULTIPLE ACCESS
TECHNOLOGIES
2
1.3.1 Frequency Division Multiple
Access
3
1.3.2 Time Division Multiple Access 3
1.3.3 Code Division Multiple Access 4
1.4 OVERVIEW OF GSM
NETWORK
4
1.5 GSM ARCHITECTURE 5
1.5.1 Network and Switching
subsystem
6
1.5.1.1 Mobile Switching Centre 6
vi
1.5.1.2 Home Location Register 6
1.5.1.3 Visitor Location Register 6
1.5.1.4 Equipment Identity
Register
7
1.5.2 Operation and Maintenance
Centre
7
1.5.3 Base Station Subsystem 8
1.5.3.1 Base Transceiver Station 8
1.5.3.2 Base Station Controller 8
1.5.4 Mobile Station 8
1.5.4.1 The Terminal 9
1.5.4.2 The SIM 9
1.6 GEOGRAPHICAL AREAS OF
THE GSM NETWORK
9
1.7 CONTROL CHANNELS 10
1.7.1 Traffic channels 11
1.7.2 Broadcast channels 11
1.7.3 Common control channels 12
1.7.4 Dedicated control channels 13
1.8 CALL SETUP IN GSM
NETWORK
14
2 LITERATURE REVIEW 15
3 GSM NETWORK PLANNING 18
3.1 INTRODUCTION TO RF
NETWORK PLANNING
18
3.2 PLANNING PROCEDURE FOR
RF NETWORK
18
vii
3.3 CAPACITY PLANNING 19
3.3.1 Network Dimensioning 19
3.3.2 Capacity calculation 20
3.3.3 Structure of Erlang B table 21
3.3.4 Frequency reuse schemes 22
3.3.5 Power budget calculations 23
3.4 COVERAGE PLANNING 23
3.5 FREQUENCY PLANNING 24
3.5.1 Frequency reuse 24
3.5.2 Frequency hopping 25
3.5.3 Implementation of frequency
hopping
25
3.5.3.1 Hopping Sequence Number 26
3.5.3.3 Rules for using HSN and
MAIO
26
3.6 PLANNING MODELS 27
4 DESIGN AND
IMPLEMENTATION
28
4.1 SOFTWARE USED 28
4.1.1 ATOLL planning tool 28
4.2 SCENARIO DESCRIPTION 29
4.3 SAMPLE PROCESS OF
WORKING OF ATOLL TOOL
29
5 RESULTS AND DISCUSSION 35
6 CONCLUSION AND FUTURE
WORK
42
REFERENCES 43
LIST OF PUBLICATIONS 46
viii
LIST OF TABLES
TABLE NO. CAPTION PAGE NO.
3.1 Erlang B table 21
3.2 BCCH channel assignment 25
3.3 TDMA frame sequence for 2/2/2 sectors 26
5.1 OMCR report before planning 36
5.2 OMCR report after planning 38
5.3 Total traffic in Erlang 39
5.4 Total Call drops 40
ix
LIST OF FIGURES
FIGURE NO. CAPTION PAGE NO.
1.1 Access Network 1
1.2 FDMA Frame 3
1.3 TDMA Frame 4
1.4 GSM Architecture 5
1.5 GSM Network Areas 9
1.6 Channels of GSM Network 10
3.1 RF Planning Process 19
4.1 New document 29
4.2 Digital Map import 30
4.3 Clutter Properties 30
4.4 Vectors import 31
4.5 Importing places 31
4.6 BTS Properties configured 32
4.7 Propagation model
configured
32
4.8 BCCH Assignment 33
4.9 Signal strength for 4 BTS 33
4.10 C/I level of 4 BTS 34
5.1 Area under Test 35
5.2 Signal Level of Area Under
Test
37
5.3 C/I Level of Area under Test 38
x
LIST OF ABBREVIATIONS
AGCH Access Grant Channel
ARFCN Absolute Radio Frequency Channel Number
ATOOL Acceptance, Test Or Launch Language
AUC Authentication Centre
BCCH Broadcast Control Channel
BSC Base Station Controller
BSS Base Station Subsystem
BTS Base Transceiver Station
CBCH Cell Broadcast Channel
CDMA Code Division Multiple Access
EIR Equipment Identity Register
FCCH Frequency Correction Channel
FDMA Frequency Division Multiple Access
GSM Global System for Mobile
HLR Home Location Register
HSN Hopping Sequence Number
ISDN International Service Digital Network
LAI Location Area Identity
LU Location Updation
MAIO Mobile Allocation and Index Offset
MS Mobile Station
MSC Mobile Switching Centre
MSISDN Mobile Station International Service Digital Network
MSRN Mobile Station Roaming Number
xi
ND Network Dimensioning
NSS Network Switching and Subsystem
OMC Operation and Maintenance Centre
OMCR Operation Maintenance Control and Radio Network
PCH Paging Channel
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
QOS Quality Of Service
RACH Random Access Channel
SCH Synchronization Channel
SIM Subscriber Identity Module
TCH Traffic Channel
TDMA Time Division Multiple Access
TMSI Temporary Mobile Subscriber Identity
VLR Visitor Location Register
1
CHAPTER-1
INTRODUCTION
1.1Introduction to Mobile Communication:
In Telecom network conventionally each user is connected to the Telephone
exchange individually. This dedicated pair starts from MDF, where it is connected to
the appropriate Equipment point and ends at the customer premises Telephone. (With
flexibility at cabinet/pillar/ distribution points DPs)
Fig 1.1. Access network
The connectivity from exchange to customer premises is called “Access
Network or Local Loop”, and mostly comprises of underground cable from exchange
up to DP‟s and insulated copper wires (Drop Wires) later on This type of Access
Network does not require separate Authentication of customer before extending
services. Whenever the cable capacity has reached the maximum additional cable is
laid to augment the capacity. Even though there are advantages in introducing wireless
connectivity in Subscriber‟s loop, we have to tackle certain issues viz,
1. Duplexing methodology.
2. Multiple Access methods.
3. Cellular principle or reuse concept.
4. Techniques to cope with “mobile” environment.
2
1.2 Duplexing Methodology:
Duplexing is the technique by which the send and receive paths are separated
over the medium, since transmission entities (modulator, amplifiers, demodulators)
are involved.
There are two types of duplexing.
• Frequency Division Duplexing (FDD)
•Time Division Duplexing (TDD)
1.2.1 Frequency Division Duplexing (FDD):
Different Frequencies are used for send and receive paths and hence there will
be a forward band and reverse band. Duplexer is needed if simultaneous transmission
(send) and reception (receive) methodology is adopted .Frequency separation between
forward band and reverse band is constant
1.2.2 Time Division Duplexing (TDD):
TDD uses different time slots for transmission and reception paths. Single radio
frequency can be used in both the directions instead of two as in FDD. No duplexer is
required. Only a fast switching synthesizer, RF filter path and fast antenna switch are
needed. It increases the battery life of mobile phones.
GSM and CDMA systems use Frequency Division Duplexing and correct uses
Time Division Duplexing.
1.3 Multiple Access methodologies:
The technique of dynamically sharing the finite limited radio spectrum by
multiple users is called Multiple Access Technique. By adopting multiple access
techniques all users cannot get the services simultaneously and some amount of
blocking is introduced by the system. This is known as GOS (Grade of Service).
Generally there are three different types of multiple access technologies. They
are
• Frequency Division Multiple Access (FDMA)
• Time Division Multiple Access (TDMA)
• Code Division multiple Access (CDMA)
3
1.3.1 Frequency Division Multiple Access (FDMA):
FDMA is a familiar method of allocating bandwidth, where a base station is
allowed to transmit on one or more number of preassigned carrier frequencies and a
mobile unit transmits on corresponding reverse channels. No other base station within
range of the mobile will be transmitting on the same forward channel, and no other
mobile within range of the base station should be transmitting on the same reverse
channel. Both the base and the mobile usually transmit continuously during a
conversation, and fully occupy their assigned forward and reverse channels. No other
conversation can take place on these channels until the first conversation is completed.
Fig 1.2. FDMA Frame
1.3.2 Time Division Multiple Access (TDMA):
TDMA is a more efficient, but more complicated way of using FDMA
channels. In a TDMA system each channel is split up into time segments, and a
transmitter is given exclusive use of one or more channels only during a particular
time period. A conversation, then, takes place during the time slots to which each
transmitter (base and mobile) is assigned. TDMA requires a master time reference to
synchronize all transmitters and receivers.
4
Fig 1.3. TDMA Frame
1.3.3 Code Division Multiple Access (CDMA):
CDMA is fundamentally different than TDMA and FDMA. Where FDMA and
TDMA transmit a strong signal in a narrow frequency band, CDMA transmits a
relatively weak signal across a wide frequency band. Using a technique called direct
sequence spread spectrum, the data to be transmitted are combined with a pseudo-
noise code (a pre-determined binary sequence that appears random) and transmitted
broadband. CDMA under Interim Standard 95 uses a bandwidth of 1.25 MHz The
pseudo-noise code (PN code) is a series of binary "chips" that are much shorter in
duration than the data bits. Since the chips appear to be in a random pattern, and there
are many chips per data bit (in IS-95 there are 128 chips for each data bit), the
modulated result appears to normal (FDMA) receivers as background noise.
1.4 Overview of GSM
Global System for Mobile Communication (GSM) is a globally accepted standard for
digital cellular communication. GSM is the name of a standardization group established
in 1982 to create a common European mobile telephone standard that would formulate
5
specifications for a pan-European mobile cellular radio system operating at 900 MHz.
GSM was devised as a cellular system specific to the 900 MHz band, called "The Primary
Band". The primary band includes two sub bands of 25 MHz each, 890 to 915 MHz and
935 MHz to 960 MHz. A GSM network is composed of several functional entities, whose
functions and interfaces are specified as,
Uplink frequency band: 890 to 915 MHz (MS transmits, BTS receives).
Downlink frequency band: 935 to 960 MHz (BTS transmits, MS receives).
1.5 GSM ARCHITECTURE
The GSM network is divided into four major systems
Network and switching subsystem(NSS)
Operation and maintenance centre(OMC)
Base station Subsystem(BSS)
Mobile station(MS)
Fig 1.4. GSM Architecture
6
1.5.1 Network and switching subsystem (NSS):
The NSS is responsible for performing call processing and subscriber-related
functions. The switching system includes the following functional units
Mobile Switching centre
Home location register
Visitor location register
Equipment identity register
Authentication centre
1.5.1.1 Mobile Switching Centre (MSC):
MSC performs all switching functions for all mobile stations, located in the
geographic area controlled by its assigned BSS‟s. Also it interfaces with PSTN, with
other MSC‟s and other system entities.
1.5.1.2 Home Location Registers (HLR):
It contains
The identity of mobile subscriber called IMSI
ISDN directory number of mobile station
Subscription information on services
Service restrictions.
1.5.1.3 Visitor Location Registers (VLR):
The VLR always integrated with the MSC. When a mobile station roams into a
new MSC area, the VLR connected to that MSC would request data about the mobile
station from the HLR. Later, if the mobile station makes a call, the VLR will have the
information needed for call setup without having to interrogate the HLR.
7
1.5.1.4 Equipment Identity Registers (EIR):
Equipment identity register consists of identity of mobile station equipment
called IMEI, which may be valid, suspect and prohibited. The information is available
in the form of three lists.
White list-The terminal which is allowed to connect to the network.
Black list-The terminal reported as stolen are not kept approved. They
are not allowed to connect to the network.
Grey list-The grey list consists of the IMEI numbers of the devices
which are outside of the white and black lists and of which electronic
communication connections are open.
1.5.1.5 Authentication Centre:
It is associated with the HLR. It stores an identity key called Ki for each
mobile subscriber. This key is used to generate the authentication
triplets.
It is authenticated using a RAND (random number).
It consists of SRES(signed response)-to authenticate IMSI.
Also, it has another key called Kc (Cipher key) to cipher
communication over the radio path between the MS and the network.
1.5.2 Operation and Maintenance Centre (OMC):
The OAM function allows the operator to monitor and control the system as
well as to modify the configuration of the elements of the system. Not only the OSS is
part of the OAM, also the BSS and NSS participate in its functions as it is shown in
the following examples:
• The components of the BSS and NSS provide the operator with all the
information it needs. This information is then passed to the OSS which is in charge of
analyzing it and control the network.
• The self-test tasks, usually incorporated in the components of the BSS and
NSS, also contribute to the OAM functions.
8
• The BSC, in charge of controlling several BTSs, is another example of an
OAM function performed outside the OSS.
1.5.3 Base Station Subsystem (BSS):
The BSS connects the Mobile Station and the NSS. It is in charge of the
transmission and reception. The BSS can be divided into two parts:
1.5.3.1 The Base Transceiver Station (BTS):
The BTS corresponds to the transceivers and antennas used in each cell of the
network. A BTS is usually placed in the centre of a cell. Its transmitting power defines
the size of a cell. Each BTS has between one and sixteen transceivers depending on
the density of users in the cell.
1.5.3.2 The Base Station Controller (BSC):
The BSC controls a group of BTS and manages their radio resources. A BSC is
principally in charge of handovers, frequency hopping, exchange functions and
control of the radio frequency power levels of the BTSs.
Characteristics of the Base Station System (BSS) are:
• The BSS is responsible for communicating with mobile stations in cell areas.
• One BSC controls one or more BTSs and can perform inter-BTS and intra-
BTS handovers.
• The BTS serves one or more cells in the cellular network and contains one or
more TRXs (Transceivers or radio units).
• The TRX serves full duplex communications to the MS.
1.5.4 Mobile Station (MS):
A Mobile Station consists of two main elements:
9
1.5.4.1 The Terminal:
There are different types of terminals distinguished principally by their power
and application:
• The `fixed' terminals are the ones installed in cars. Their maximum allowed
output power is 20 W.
• The GSM portable terminals can also be installed in vehicles. Their maximum
allowed output power is 8W.
• The handheld terminals have experienced the biggest success thanks to the
weight and volume, which are continuously decreasing. These terminals can emit up
to 2 W. The evolution of technologies allows decreasing the maximum allowed power
to 0.8 W.
1.5.4.2 The SIM:
The SIM is a smart card that identifies the terminal. By inserting the SIM card
into the terminal, the user can have access to all the subscribed services. Without the
SIM card, the terminal is not operational. The SIM card is protected by a four-digit
Personal Identification Number (PIN). In order to identify the subscriber to the
system, the SIM card contains some parameters of the user such as its International
Mobile Subscriber Identity (IMSI). Another advantage of the SIM card is the mobility
of the users. In fact, the only element that personalizes a terminal is the SIM card.
Therefore, the user can have access to its subscribed services in any terminal using its
SIM card.
1.6 GEOGRAPHICAL AREAS OF THE GSM NETWORK
Fig 1.5. GSM network areas
10
The figure 1.5 represents the different areas that form a GSM network. As it
has already been explained a cell, identified by its Cell Global Identity number (CGI),
corresponds to the radio coverage of a base transceiver station. A Location Area (LA),
identified by its Location Area Identity (LAI) number, is a group of cells served by a
single MSC/VLR. A group of location areas under the control of the same MSC/VLR
defines the MSC/VLR area. A Public Land Mobile Network (PLMN) is the area
served by one network operator.
1.7 Control channels:
One or more logical channel scan be transmitted on a physical channel. There
are different types of logical channels. The type of logical channel is determined by
the function of the information transmitted over it.
The following types of logical channels exist:
Traffic channels
Broadcast channels
Common control channels
Dedicated control channels
Note that the first channel type carries speech and data, and the other types
control information (signalling).
Fig 1.6. Channels of GSM Network
11
1.7.1 TRAFFIC CHANNELS
The traffic channels are used to send speech or data services. There are two
types of traffic channels. They are distinguished by their transmission rates.
The following traffic channels are provided:
TCH/F (Traffic Channel Full rate)
The TCH/F carries information at a gross bit rate of 22.8 kbit/s (after channel
coding). The net (or effective) bit rate at the TCH/F is for speech 13 kbit/s and for data
12, 6 or 3.6 kbit/s (before channel coding). The transmission rates of the data services
allow services which are compatible to the existing, respectively, 9.6, 4.8 and 2.4
kbit/s PSTN and ISDN services.
TCH/HR (Traffic Channel Half rate)
The TCH/H carries information at a gross bit rate of 11.4 kbit/s. The net bit rate
at the TCH/H is for speech 5.6 kbit/s and for data 6 or 3.6 kbit/s.
TCH/EFR (Enhanced Full rate)
The EFR provides a voice coding algorithm offering improved speech quality.
The algorithm is fully compatible with a BSM speech quality. The algorithm is fully
compatible with a GSM 13 kbit/s speech channel. The main benefit will be improved
voice quality which offers prospects to compete with PSTN networks.
1.7.2 BROADCAST CHANNELS
The information distributed over the broadcast channels helps the mobile
stations to orient themselves in the mobile radio network. The broadcast channels are
point-to-multipoint channels which are only defined for the downlink direction (BTS
to the mobile station). They are four types:
BCCH (Broadcast Control Channel)
The mobile station is informed about the system configuration parameters (for
example Local Area Identification, Cell Identity and Neighbour Cells). Using this
12
information the mobile stations can choose the best cell to attach to. The BCCH is also
known as beacon.
FCCH (Frequency Correction Channel)
To communicate with the BTS the mobile station must tune to the BTS. The
FCCH transmits a constant frequency shift of the radio frequency carrier that can be
used by the mobile station for frequency correction.
SCH (Synchronization Channel)
The SCH is used to time synchronize the mobile stations. The data on this
channel carries the TDMA frame number and the BSIC (Base Station Identity Code).
CBCH (Cell Broadcast Channel)
The CBCH is used for the transmission of generally accessible information
(Short Message Service messages) in a cell, which can be polled by the mobile station.
1.7.3 COMMON CONTROL CHANNELS
Common control channels are specified as point-to-multipoint channels which
only operate in one direction of transmission, either in the uplink or downlink
direction. There are three types:-
PCH (Paging Channel)
The PCH is used in the downlink direction for paging the mobile stations.
AGCH (Access Grant Channel)
The AGCH is also used in the downlink direction. A logical channel for a
connection is allocated via the AGCH if the mobile station has requested such a
channel via the RACH.
13
RACH (Random Access Channel)
The RACH is used in the uplink direction by the mobile stations for requesting
a channel for a connection. It is an access channel that uses the slotted Aloha access
scheme.
1.7.4 DEDICATED CONTROL CHANNELS
Dedicated control channels are full-duplex, point-to-point channels. They are
used for signaling between the BTS and a certain mobile station.
SACCH (Slow Associated Control Channel)
The SACCH is a duplex channel which is always allocated to a TCH or
SDCCH. The SACCH is used for transmission of signaling data, radio link
supervision measurements, transmit power control and timing advance data. Note that
the SACCH is only used for non-urgent procedures.
FACCH (Fast Associated Control Channel)
The FACCH is used as a main signalling link for the transmission of signalling
data (for example handover commands). It is also required for every call set-up and
release. During the call the FACCH data is transmitted over the allocated TCH instead
of traffic data; this is marked by a flag called a stealing flag. The process of stealing a
TCH for FACCH data is called pre-emption.
SDCCH (Stand-alone Dedicated Control Channel)
The SDCCH is a duplex, point-to-point channel which is used for signaling in
higher layers. It carries all signaling between the BTS and the mobile station when no
TCH is allocated. The SDCCHs are used for service requests (for example Short