THIS TOPIC COVERS ABOUT TELECOMMUNICATION SYSTEM

1. MOBILE TELECOMMUNICATION SYSTEM
Presented By
W.FATHIMA FARSANA
DEPARTMENT OF COMPUTER APPLICATION
SADAKATHULLAH APPA COLLEGE
TIRUNELVELI

2. MOBILE TELECOMMUNICATION SYSTEM
Cellular Network Organization
 Use multiple low-power transmitters (Base station) (100 W or less)
 Areas divided into cells
 Each served by its own antenna
 Served by base station consisting of transmitter, receiver, and control unit
 Band of frequencies allocated
 Cells set up such that antennas of all neighbors are equidistant(Hexagonal pattern)
 Cellular systems implements Space Division Multiplexing Technique(SDM). Each
transmitter is called a base station and can cover a fixed area called a cell. This area can
vary from few meters to few kilometers.
 Mobile network providers install several thousands of base stations each with a smaller
cell instead of using power full transmitters with large cells
CELLULAR SYSTEM LAYOUT
Basic concepts:

3.  High capacity is achieved by limiting the coverage of each base station to a small
geographic region called a cell
 Same frequencies/ timeslots/codes are reused by spatially separated basestation
 A switching technique called handoff enables a call to proceed uninterrupted when one
user moves from one cell to another
 Neighboring base stations are assigned different group of channels so as to minimize the
interference
 By systematically spacing base station and the channels group may be reused as many
number of times as necessary
 As demand increases the number of base stations may be increased thereby providing
additional capacity
Frequency Reuse

4.  adjacent cells assigned different frequencies to avoid interference or crosstalk
 Objective is to reuse frequency in nearby cells
 10 to 50 frequencies assigned to each cell
Advantages
Higher capacity
Smaller the size of the cell more the number of concurrent user’s i.e. huge cells do not allow
for more concurrent users.
Less transmission power
Huge cells require a greater transmission power than small cells.
Local interference only
For huge cells there are a number of interfering signals, while for small cells there is limited
interference only.
Robustness
As cellular systems are decentralized, they are more robust against the failure of single
components.
Disadvantages:
Infrastructure needed: Cellular systems need a complex infrastructure to connect all base stations
Handover needed: The mobile station has to perform a handover when changing from one cell
to another.
GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM)
 GSM stands for Global System for Mobile Communication. It is a digital cellular
technology used for transmitting mobile voice and data services.
formerly: Group Special Mobile (founded 1982)
now: Global System for Mobile Communication
 GSM offers several types of connections voice connections, data connections, short
message service
GSM offers three basic types of services:

5.  Telephony services or teleservices
 Data services or bearer services
 Supplementary services
GSM SERVICES AND FEATURES
Teleservices
The abilities of a Bearer Service are used by a Teleservice to transport data. These services
are further transited in the following ways:
 Voice Calls
The most basic Teleservice supported by GSM is telephony. This includes full-rate speech at
13 kbps and emergency calls, where the nearest emergency-service provider is notified by
dialing three digits.
 Videotext and Facsmile
Another group of teleservices includes Videotext access, Teletex transmission, Facsmile
alternate speech and Facsmile Group 3, Automatic Facsmile Group, 3 etc.
 Short Text Messages
Short Messaging Service (SMS) service is a text messaging service that allows sending and
receiving text messages on your GSM mobile phone. In addition to simple text messages, other
text data including news, sports, financial, language, and location-based data can also be
transmitted.
Bearer Services
 Data services or Bearer Services are used through a GSM phone. to receive and send data
is the essential building block leading to widespread mobile Internet access and mobile
data transfer.
Different data rates for voice and data (original standard)
Data Service (circuit switched)
 synchronous: 2.4, 4.8 or 9.6 kbit/s
 asynchronous: 300 - 1200 bit/s
Data service (packet switched)

6.  synchronous: 2.4, 4.8 or 9.6 kbit/s
 asynchronous: 300 - 9600 bit/s
Supplementary Services
 Supplementary services are additional services that are provided in addition to
teleservices and bearer services. These services include caller identification, call
forwarding, call waiting, multi-party conversations, and barring of outgoing
(international) calls, among others. A brief description of supplementary services is given
here:
 Conferencing : It allows a mobile subscriber to establish a multiparty conversation, i.e., a
simultaneous conversation between three or more subscribers to setup a conference call.
This service is only applicable to normal telephony.
 Call Waiting : This service notifies a mobile subscriber of an incoming call during a
conversation. The subscriber can answer, reject, or ignore the incoming call.
 Call Hold : This service allows a subscriber to put an incoming call on hold and resume
after a while. The call hold service is applicable to normal telephony.
 Call Forwarding : Call Forwarding is used to divert calls from the original recipient to
another number. It is normally set up by the subscriber himself. It can be used by the
subscriber to divert calls from the Mobile Station when the subscriber is not available,
and so to ensure that calls are not lost.
 Call Barring : Call Barring is useful to restrict certain types of outgoing calls such as
ISD or stop incoming calls from undesired numbers. Call barring is a flexible service that
enables the subscriber to conditionally bar calls.
 Number Identification : There are following supplementary services related to number
identification:
 Calling Line Identification Presentation : This service displays the telephone number
of the calling party on your screen.
 Calling Line Identification Restriction : A person not wishing their number to be
presented to others subscribes to this service.
 Connected Line Identification Presentation : This service is provided to give the
calling party the telephone number of the person to whom they are connected. This

7. service is useful in situations such as forwarding's where the number connected is not the
number dialed.
 Connected Line Identification Restriction : There are times when the person called
does not wish to have their number presented and so they would subscribe to this person.
Normally, this overrides the presentation service.
 Malicious Call Identification : The malicious call identification service was provided to
combat the spread of obscene or annoying calls. The victim should subscribe to this
service, and then they could cause known malicious calls to be identified in the GSM
network, using a simple command.
 Advice of Charge (AoC) : This service was designed to give the subscriber an indication
of the cost of the services as they are used. Furthermore, those service providers who
wish to offer rental services to subscribers without their own SIM can also utilize this
service in a slightly different form. AoC for data calls is provided on the basis of time
measurements.
 Closed User Groups (CUGs) : This service is meant for groups of subscribers who wish
to call only each other and no one else.
 Unstructured supplementary services data (USSD) : This allows operator-defined
individual services.
Architecture of the GSM system
 GSM is a PLMN (Public Land Mobile Network)
 several providers setup mobile networks following the GSM standard within each
country
Components
 MS (mobile station)
 BS (base station)
 MSC (mobile switching center)
 LR (location register)
Subsystems
A GSM system consists of three main subsystems

8.  RSS (radio subsystem): covers all radio aspects
 NSS (network and switching subsystem): call forwarding,handover, switching
 OSS (operation subsystem): management of the network
 A schematic architecture of the GSM is shown in the figure
RADIO SUBSYSTEM
The subsystem comprises all the radio specific entities,that is the
 MOBILE STATION
 BASE STATION SUBSYSTEM
 BASE TRANSIVIER STATION
Mobile Station(MS)
The Mobile Station is made up of two entities:

9.  Mobile Equipment (ME)
 Subscriber Identity Module (SIM)
Mobile Equipment (ME)
 Portable, vehicle mounted, hand held device
 Uniquely identified by an IMEI (International Mobile Equipment Identity)
 Voice and data transmission
 Monitoring power and signal quality of surrounding cells for optimum handover
 Power level : 0.8W – 20 W
 160 character long SMS.
Subscriber Identity Module(SIM)
 Smart card contains the International Mobile Subscriber Identity (IMSI)
 Allows user to send and receive calls and receive other subscribed services
 Protected by a password or PIN
 Can be moved from phone to phone –
 contains key information to activate the phone
Base Station Sub System
BSC(Base Station Controller) —The BSC provides all the control functions and physical links
between the MSC and BTS. It is a high-capacity switch that provides functions such as
handover, cell configuration data, and control of radio frequency (RF) power levels in base
transceiver stations. The BSC is the connection between the Mobile Station and Mobile
Switching Center.
BTS(Base Transceiver Station) —The BTS handles the radio interface to the mobile station.
The BTS is the radio equipment (transceivers and antennas) needed to service each cell in the
network. A group of BTSs are controlled by a BSC. controls multiple BTSs and manages radio
channel setup, and handovers.

10. Base Station Sub-System
Network and Switching Sub System
This subsystem forms the heart of the GSM system.It connects the wireless networks to
the standard public network and carries out the usage based charging,accounting and also
handles the roaming.It consists of the following
• Home location register (HLR) —The HLR is a database used for storage and
management of subscriptions. The HLR is considered the most important database, as it

11. stores permanent data about subscribers, including a subscriber's service profile,location
information, and activity status.
• Mobile services switching center (MSC) —The MSC performs the telephony switching
functions of the system. It controls calls to and from other telephone and data systems. It
also performs such functions as toll ticketing, network interfacing,common channel
signaling, and others.
• Visitor location register (VLR) —The VLR is a database that contains temporary
information about subscribers that is needed by the MSC in order to service visiting
subscribers. The VLR is always integrated with the MSC
OPERATION SUB SYSTEM
The operation subsystem consists of all the necessary functions for network operation and
maintenance. It consists the following
Authentication center (AUC) —A unit called the AUC provides authentication and
encryption parameters that verify the user's identity and ensure the confidentiality of each
call. The AUC protects network operators from different types of fraud found in today's
cellular world.
Equipment identity register (EIR) —The EIR is a database that contains information about
the identity of mobile equipment that prevents calls from stolen, unauthorized, or defective
mobile stations. The AUC and EIR are implemented as stand-alone nodes or as a combined
AUC/EIR node.
Base Station System/Radio Sub-System

12. Security in GSM
Security services
 Access control/authentication
 User SIM (Subscriber Identity Module): secret PIN (personal identification number)
 SIM network: challenge response method
 Confidentiality
 voice and signaling encrypted on the wireless link (after successful authentication)
 temporary identity TMSI (Temporary Mobile Subscriber Identity)
 newly assigned at each new location update (LUP)
 encrypted transmission
3 algorithms specified in GSM
 A3 for authentication (“secret”, open interface)
 A5 for encryption (standardized)
 A8 for key generation (“secret”, open interface)
GSM Security
 Authentication

13.  network operator can verify the identity of the subscriber making it infeasible to
clone someone else’s mobile phone
 Confidentiality
 protects voice, data and sensitive signalling information (e.g. dialled digits)
against eavesdropping on the radio path
 Anonymity
 protects against someone tracking the location of the user or identifying calls
made to or from the user by eavesdropping on the radio path
GSM Security Mechanisms
 Authentication
 challenge-response authentication protocol
 encryption of the radio channel
 Confidentiality
 encryption of the radio channel
 Anonymity
use of temporary identities
GSM Security Architecture
 Each mobile subscriber is issued with a unique 128-bit secret key (Ki)
 This is stored on a Subscriber Identity Module (SIM) which must be inserted into the
mobile phone
 Each subscriber’s Ki is also stored in an Authentication Centre (AuC) associated with the
HLR in the home network
 The SIM is a tamper resistant smart card designed to make it infeasible to extract the
customer’s Ki

14.  GSM security relies on the secrecy of Ki
 if the Ki could be extracted then the subscription could be cloned and the
subscriber’s calls could be eavesdropped
 even the customer should not be able to obtain Ki
AUTHENTICATION
 Authentication key Ki,, the user identification IMSI, and the algorithmused for
authentication A3 is stored in the sim. This is known only to the MS and BTS.
 Authentication uses a challenge-response method: The access control AC (BTS)
generates a random number RAND this is called as challenge, and the SIM within the MS
reply with SRES (signed response). This is called as SRES response.
 N/W side: BTS send random number RAND to MS.

15.  MS side: MS prepares SRES response by giving the random number RAND and Ki, to
the algorithm A8.The output is the SRES which is sent to the BTS.
 BTS side: BTS also prepares the same SRES and the output from the MS is compared
with result created by the BTS. If they are the same, the BTS accepts the subscriber,
otherwise the subscriber is rejected.
CONFIDENTIALITY/ENCRYPTION
 To maintain the secrecy of the conversation, all messages are encrypted in GSM.
Encryption is done by giving the cipher key Kc with message to the algorithm A5 .Here
the key is generated separately
 Kc is generated using the Ki which is stored in SIM and a random number RAND given
by BTS, by applying the algorithm A8.
 Note that the SIM in the MS and the network both calculate the same Kc based on the
random value RAND. The key Kc itself is not transmitted over the air.
ANONYMITY
 A GSM networks protects against someone tracking the location of a user or identifying
calls made to or from the user.

16.  The anonymity of the subscriber on the radio access link in the GSM network is achieved
by allocating Temporary Mobile Subscriber Identity(TMSI)instead of permanent
identities.
 This helps to protect against tracking users location and obtaining information about a
users calling pattern.
GSM Security Features
 Key management is independent of equipment Subscribers can change handsets without
compromising security
 Subscriber identity protection not easy to identify the user of the system intercepting a
user data
 Detection of compromised equipment – Detection mechanism whether a mobile device
was compromised or not
 Subscriber authentication - The operator knows for billing purposes who is using the
system
 Signaling and user data protection- Signaling and data channels are protected over the
radio path
General packet radio service (GPRS)
General packet radio service (GPRS) is a packet oriented mobile data service on the 2G and
3G cellular communication system's global system for mobile communications(GSM). GPRS
was originally standardized by European Telecommunications Standards Institute (ETSI) in
response to the earlier CDPD and i-mode packet-switched cellular technologies.
 Networks based on the Internet Protocol (IP) and X.25
 Theoretically maximum rate is just 171. 2 Kbits/sec.
 A realistic estimation on transfer is between 5 and 40 kbps.
 It applies a packet radio principle to transfer user data packets in an efficient way.
 This principle offers a more user-friendly billing than that offered by circuit switched
services.

17.  User can be "online" over a long period of time but will be billed based on the
transmitted data volume.
GPRS Architecture
GPRS architecture introduces two new network elements
 Serving GPRS support node(SGSN)
 Gateway GPRS support Node(GGSN)
Serving GPRS support node(SGSN)
A serving GPRS support node (SGSN) is responsible for
 Delivery of data packets from and to the mobile stations within its service area.
 Packet routing and transfer

18.  Mobility management (attach/detach and location management)
 Authentication and charging functions. The location register of the SGSN stores location
information and user profiles (IMSI, addresses used in the packet data network) of all
GPRS users registered with this SGSN.
Gateway GPRS support Node(GGSN)
A gateway GPRS support node (GGSN) acts as an
 interface between the GPRS backbone network and the external packet data networks.
 It converts the GPRS packets coming from the SGSN into the appropriate packet data
protocol (PDP) format (IP or X.25) and sends them out on the corresponding packet data
network.
 In the other direction, PDP addresses of incoming data packets are converted to the GSM
address of the destination user. The readdressed packets are sent to the responsible
SGSN. For this purpose, the GGSN stores the current SGSN address of the user and his
or her profile in its location register.
 Also performs authentication and charging functions.
GPRS Mobility Management
 GPRS Attachment
 GPRS Detachment
 Location Management
GPRS Attachment Procedure
Before a mobile station can use GPRS services, it must register with an
 SGSN of the GPRS network. This procedure follows as
 mobile is authenticated with the mobile's Home Location Register

19.  SGSN does an update of the GPRS location
 SGSN sends an "Attach Accept" message to the mobile
 mobile responds with an "Attach Complete“
 Attach request which includes IMSI which then processed by the network to P-TMSI.
GPRS Detachment Procedure
 The disconnection from the GPRS. It can be initiated by the mobile station or by the
network (SGSN).
 In MS initiated one; MS informs that it wants to leave the system, this is MS’s wish. If
any contexts are active, network will clear them. Afterwards MS’s location is not tracked
anymore.
 In Network initiated one; Network wants to “get rid of the MS” because of;

20.  behaving mobile
 Congested network
 Immediate service termination (IST)(E.g. Bills are not paid)
 Load new parameters (Configuration has been changed and they should be taken into
use)
GPRS - PDP Context
 PDP stands for Packet Data Protocol. The PDP addresses are network layer addresses
(Open Standards Interconnect [OSI] model Layer 3). GPRS systems support both X.25
and IP network layer protocols. Therefore, PDP addresses can be X.25, IP, or both.
 Each PDP address is anchored at a Gateway GPRS Support Node (GGSN), as shown in
figure below. All packet data traffic sent from the public packet data network for the PDP
address goes through the gateway (GGSN).

21.  The public packet data network is only concerned that the address belongs to a specific
GGSN. The GGSN hides the mobility of the station from the rest of the packet data
network and from computers connected to the public packet data network.
 Statically assigned PDP addresses are usually anchored at a GGSN in the subscriber's
home network. Conversely, dynamically assigned PDP addresses can be anchored either
in the subscriber's home network or the network that the user is visiting.
 When a MS is already attached to a SGSN and it is about to transfer data, it must activate
a PDP address. Activating a PDP address establishes an association between the current
SGSN of mobile device and the GGSN that anchors the PDP address.
 The record kept by the SGSN and the GGSN regarding this association is called the
PDP context.

22.  It is important to understand the difference between a MS attaching to a SGSN and a MS
activating a PDP address. A single MS attaches to only one SGSN, however, it may have
multiple PDP addresses that are all active at the same time.
 Each of the addresses may be anchored to a different GGSN. If packets arrive from the
public packet data network at a GGSN for a specific PDP address and the GGSN does not
have an active PDP context corresponding to that address, it may simply discard the
packets. Conversely, the GGSN may attempt to activate a PDP context with a MS if the
address is statically assigned to a particular mobile device.
GPRS - Data Routing
Data routing or routing of data packets to and fro from a mobile user, is one of the pivot
requisites in the GPRS network. The requirement can be divided into two areas:
 Data packet routing
 Location management.
Data Packet Routing
 The GGSN updates the location directory using routing information supplied by the
SGSNs about the location of an MS. It routes the external data network protocol packet
encapsulated over the GPRS backbone to the SGSN currently serving the MS. It also
decapsulates and forwards external data network packets to the appropriate data network
and collects charging data that is forwarded to a charging gateway (CG).
 There are three important routing schemes:
 Mobile-originated message - This path begins at the GPRS mobile device and ends at
the host.

23.  Network-initiated message when the MS is in its home network - This path begins at
the host and ends at the GPRS mobile device.
 Network-initiated message when the MS roams to another GPRS network - This
path begins at the host of visited network and ends at the GPRS mobile device.
 The GPRS network encapsulates all data network protocols into its own encapsulation
protocol called the GPRS tunnelling protocol (GTP). The GTP ensures security in the
backbone network and simplifies the routing mechanism and the delivery of data over the
GPRS network.
Location Management
 Aim is to keep track of the user's current location,so that incoming packets can be routed
to his or her MS.
 A MS can be in one of three states depending on its current traffic amount; the location
update frequency is dependent on the state of the MS.
Active State

24.  Data is transmitted between an MS and the GPRS network only when the MS is in the
active state. In the active state, the SGSN knows the cell location of the MS.
 Packet transmission to an active MS is initiated by packet paging to notify the MS of an
incoming data packet.
 The data transmission proceeds immediately after packet paging through the channel
indicated by the paging message.
 The purpose of the paging message is to simplify the process of receiving packets.
 The MS listens to only the paging messages instead of to all the data packets in the
downlink channels. This reduces battery usage significantly.
 When an MS has a packet to transmit, it must access the uplink channel (i.e., the channel
to the packet data network where services reside). T
 he uplink channel is shared by a number of MSs, and its use is allocated by a BSS(base
station subsystem). The MS requests use of the channel in a random access message.
 The BSS allocates an unused channel to the MS and sends an access grant message in
reply to the random access message.
Standby State
 In the standby state, only the routing area of the MS is known. (The routing area can
consist of one or more cells within a GSM location area).
 When the SGSN sends a packet to an MS that is in the standby state, the MS must be
paged. Because the SGSN knows the routing area of the MS, a packet paging message is
sent to the routing area.
 On receiving the packet paging message, the MS relays its cell location to the SGSN to
establish the active state.
Idle State

25.  In the idle state, the MS does not have a logical GPRS context activated or any Packet-
Switched Public Data Network (PSPDN) addresses allocated.
 In this state, the MS can receive only those multicast messages that can be received by
any GPRS MS.
 Because the GPRS network infrastructure does not know the location of the MS, it is not
possible to send messages to the MS from external data networks.
Routing Updates
 When an MS that is in an active or a standby state moves from one routing area to
another within the service area of one SGSN, it must perform a routing update. The
routing area information in the SGSN is updated, and the success of the procedure is
indicated in the response message.
 A cell-based routing update procedure is invoked when an active MS enters a new cell.
The MS sends a short message containing the identity of the MS and its new location
through GPRS channels to its current SGSN. This procedure is used only when the MS is
in the active state.
 The inter-SGSN routing update is the most complicated routing update. The MS changes
from one SGSN area to another, and it must establish a new connection to a new SGSN.
This means creating a new logical link context between the MS and the new SGSN and
informing the GGSN about the new location of the MS
.
GPRS - Quality of Service
 The QoS is a vital feature of GPRS services as there are different QoS support
requirements for assorted GPRS applications like realtime multimedia, web browsing,
and e-mail transfer.
 GPRS allows defining QoS profiles using the following parameters :

26.  Service Precedence
 Reliability
 Delay and
 Throughput
Service Precedence
 The preference given to a service when compared to another service is known as Service
Precedence.This level of priority is classified into three levels called:
 high
 normal
 low
 When there is network congestion, the packets of low priority are discarded as compared
to high or normal priority packets.
Reliability
This parameter signifies the transmission characteristics required by an application.The
reliability classes are defined which guarantee certain maximum values for the probability of
loss, duplication, mis-sequencing, and corruption of packets
Delay
 The delay is defined as the end-to-end transfer time between two communicating mobile
stations or between a mobile station and the GI interface to an external packet data
network.
 This includes all delays within the GPRS network, e.g., the delay for request and
assignment of radio resources and the transit delay in the GPRS backbone network.
Transfer delays outside the GPRS network, e.g., in external transit networks, are not
taken into account.

27. Throughput
 The throughput specifies the maximum/peak bit rate and the mean bit rate.
 Using these QoS classes, QoS profiles can be negotiated between the mobile user and the
network for each session, depending on the QoS demand and the available resources.
 The billing of the service is then based on the transmitted data volume, the type of
service, and the chosen QoS profile.
GPRS Billing Techniques
 The SGSN and GGSN register all possible aspects of a GPRS user's behavior and
generate billing information accordingly. This information is gathered in so-called
Charging Data Records (CDR) and is delivered to a billing gateway.
 The GPRS service charging can be based on the following parameters:
 Volume - The amount of bytes transferred, i.e., downloaded and uploaded.
 Duration - The duration of a PDP context session.
 Time - Date, time of day, and day of the week (enabling lower tariffs at offpeak hours).
 Final destination - A subscriber could be charged for access to the specific network,
such as through a proxy server.
 Location - The current location of the subscriber.
 Quality of Service - Pay more for higher network priority.
 SMS - The SGSN will produce specific CDRs for SMS.
 Served IMSI/subscriber - Different subscriber classes (different tariffs for frequent
users, businesses, or private users).
 Reverse charging - The receiving subscriber is not charged for the received data;
instead, the sending party is charged.

28.  Free of charge - Specified data to be free of charge.
 Flat rate - A fixed monthly fee.
 Bearer service - Charging based on different bearer services (for an operator who has
several networks, such as GSM900 and GSM1800, and who wants to promote usage of
one of the networks). Or, perhaps the bearer service would be good for areas where it
would be cheaper for the operator to offer services from a wireless LAN rather than from
the GSM network.
Universal Mobile Telecommunications
System(UMTS)
 UMTS is developed by 3GPP (3 Generation Partnership Project) a joint venture of
several organization
 3G UMTS is a third-generation (3G): broadband, packet-based transmission of text,
digitized voice, video, multimedia at data rates up to 2 Mbps
 Also referred to as wideband code division multiple access(WCDMA)
 Allows many more applications to be introduce to a worldwide
 Also provide new services like alternative billing methods or calling plans.
 The higher bandwidth also enables video conferencing or IPTV.
 Once UMTS is fully available, computer and phone users can be constantly attached to
the Internet wherever they travel and, as they roam, will have the same set of capabilities.
Features
 It uses FDD/TDD duplexing method.
 It uses the Bandwidth of 5 MHz. ´
 The Chip rate is about 3.84 Mbps
 It is very much flexible with 100/200 kHz carrier spacing. ´

29.  The Frame length unit is 10 ms.
 It has variable spreading factor.
 The maximum data rat for indoor is 2 Mbps and for mobile it is 384 kbps.
UMTS Modes
 It has two modes.
 I) UMTS-FDD ii) UMTSTDD.
 In frequency division duplex mode there are two frequencies used one for the uplink and
the other for the downlink.
 In Time division duplex mode only one frequency is used for both uplink and downlink,
but the frequency is divided into time slots for uplink and downlink communication.

30. Types of Cells and its Data Rates
In these networks coverage is provided by a combination of various cell sizes
Macro Cell
 These cover a large area and will give slow access.
 144 Kbps – max speed of 500 Km/h. Low data rate.
Micro Cell
 These should cover a medium area.
 384 Kbps max speed 120 Km/h. Medium data rate.

31. Pico Cell
 Less than 100 metres.
 2 Mbps – max speed of 10 Km/h. High data rate
Architecture of UMTS
The UMTS network architecture can be divided into three main elements
 User Equipment
 UMTS Terrestrial Radio Access network
 Core Network
User Equipment
 It is not a simple mobile phone but rather, a mobile multimedia terminal provides
simultaneously voice, video and data services.
 UE is composed of two parts –
 Mobile Equipment(ME)
 Universal subscriber identity module (USIM).

32. Mobile Equipment
 It performs reliable data and signalling message transfer throughout the radio Interface.
 User data is generated in uplink and processed in the downlink, Application protocols
such as WAP/IP are located in the TE(Terminal Equipment).
USIM
 Information located in USIM are:
 The personal identification Number(PIN).
 The preferred languages
 The codes to enable emergency call
 One or several IMSI(international mobile subscriber identity) and MSISDN(mobile
subscriber integrated services digital network ).
 The user’s temporary identities allocated.
 Circuit and packet switched temporary location information.
UTRAN (UMTS Terrestrial Radio Access network)
 The UMTS(UMTS Terrestrial Radio Access network) has two elements:
 RNC (radio network controller)
 Node B.
 UTRAN is subdivided into individual radio network (RNS), where each RNS is
controlled by RNC.
 The RNC is connected to a set of Node B elements, each of which can serve one or
several cells.
Radio Network Controller (RNC)

33.  A radio network controller (RNC) is a governing element in the UMTS radio
access network (UTRAN) and is responsible for controlling the Node Bs that are
connected to it.
 The RNC carries out radio resource management, some mobility management functions
and encrypts data before it is sent to and from the mobile.
Node B
 Node B is the physical unit for radio TX/RX with cells.
 A single Node B can support both FDD and TDD modes.
 The Main task of Node B is the conversion of data to and from th Uu radio interface,
including forward error correction (FEC)
 Node B also participates in power control.
Core Network
The UMTS core network may be split into two different areas:
Circuit switched elements:
 Carry data in a circuit switched manner, i.e. a permanent channel for the duration of the
call.
Packet switched elements:
 Carry packet data. This enables much higher network usage as the capacity can be shared
and data is carried as packets which are routed according to their destination.
Shared Elements
Circuit switched elements
The circuit switched elements of the UMTS core network architecture include the following
network entities:

34. Mobile switching center (MSC):
 An exchange performing all the switching and signalling functions
Functions
 –call management
 –mobility management(handling attach and authentication)
 –subscriber administration
 –maintenance of charging data(for radio network usage)
 –supplementary call services (call forwarding, etc.)
Gateway MSC (GMSC)
 The Gateway Mobile Switching Center (GMSC) is a type of Mobile Switching Center
(MSC) that is used to route calls outside the mobile network. Mobile Switching Center
Servers (MSC-S) provide control of high-capacity switching in mobile circuit core
networks for operators to control services and switching.
 Provides interconnection between the UMTS core network and external Public Switched
Telephone Network (PSTN)/ Integrated Services Digital Network (ISDN)networks.
Packet switched elements
 The packet switched elements of the 3G UMTS core network architecture include the
following network entities:
Serving GPRS Support Node (SGSN)
The SGSN provides a number of functions within the UMTS network architecture.
 Mobility management
 Session management:
 Interaction with other areas of the network:

35.  Billing
Gateway GPRS Support Node (GGSN):
 Central element in UMTS.
 It handles inter-working between the UMTS packet switched network and external packet
switched networks.
Shared Elements
The shared elements of the 3G UMTS core network architecture include the following network
entities:
Home location register (HLR):
 Contains all the administrative information about each subscriber along with their last
known location
Equipment identity register (EIR):
 The EIR is the entity that decides whether a given UE equipment may be allowed onto
the network or not on the basis of IMEI.
Authentication centre (AuC) :
 The AuC is a protected database that contains the secret key also contained in theuser's
USIM card.
Major Interface
There are four major new interfaces defined in UMTS:
Iu The interface between UTRAN and the CN. This is the circuit-switched connection for
carrying (typically) voice traffic and signaling between the UTRAN and the core voice network.
 The main signaling protocol used is Radio Access Network Application Part (RANAP).
Iur The Interface between different RNCs.

36.  The primary purpose of the Iur interface is to support inter-MSC mobility. When a
mobile subscriber moves between areas served by different RNCs, the mobile
subscriber’s data is now transferred to the new RNC via Iur.
 The original RNC is known as the serving RNC and the new RNC is known as the drift
RNC.
 The main signaling protocol used is Radio Network Subsystem Application Part
(RNSAP).
Iub The interface between the Node B and the RNC. This is the interface used by an RNC to
control multiple Node Bs.
 The main signaling protocol used is Node B Application Part (NBAP).
 The equivalent interface in GSM/GPRS networks is the A-bis interface.
 The Iubinterface is the main standardized and open, unlike the A-bis interface.
Uu This is the interface between the user equipment and the network. That is, it is the UMTS
air interface.
General Protocol Model

37.  Signaling bearers are used to transmit higher layers, signaling and control
information.
 Data bearers are the frame protocols used to transport user data.
 Application protocols are used to provide UMTS- specific signaling an control with in
UTRAN such as to set up bearers in theradio network layer
 Data streams contain the user data that is transparently transmitted between the
network elements.
 Access link control application part protocol layers . They react to the radio network
slayer’s demands to set up, maintain and release data bearers.