Agenda
⮚ The Universal Mobile Communication Services (UMTS) and its
benefits over the 2G mobile Communication
⮚ Technologies used in UMTS
⮚ Wideband Code Division Multiple Access technology
⮚ WCDMA Radio network system architecture.
⮚ UMTS core network elements
⮚ Various domains in 3G Core Network
2

Feaures of 3G systems
 Bit rates up to 2Mbps
 Variable bit rate to offer bandwidth on demand
 Multiplexing of services with different Qos requirements on a single
connection
 Quality requirements from 10% frame error rate to 10-6 bit error rate.
 Co-existence with different systems and inter-system handovers for
coverage enhancements and loading balancing.
 Uplink and downlink asymmetry e.g. web browsing causes more
loading to downlink than to uplink.
 High spectrum efficiency
 Co-existence of FDD (Frequency division duplex) and TDD (time
division duplex) modes
3

3G Standardization Environment
4

Summary of 3GPP network architectures
5

WCDMA RADIO ACCESS NETWORK
6

RADIO BASE STATION (NODE B)
 The Radio Base Station
handles the radio
transmission and reception
to/from the handset over the
radio interface (Uu)
 It is controlled from the Radio
Network Controller via the
Iub interface
 One Radio Base Station can
handle one or more cells
7

FUNCTIONS OF NODE B
 Radio transmission and reception
 Involved in the mobility management
 Involved in the power control
 Modulation / Demodulation
 Closed loop power control
8

RADIO NETWORK CONTROLLER (RNC)
• Controls all WCDMA Radio Access Network functions.
• It connects the WCDMA Radio Access Network to the
core network via the Iu interface.
9

RADIO NETWORK CONTROLLER (RNC)
RNC types
 Serving RNC
 Controlling RNC
 The Serving RNC has overall control of the handset that is
connected to WCDMA Radio Access Network
 It controls the connection on the Iu interface for the
handset and it terminates several protocols in the contact
between the handset and the WCDMA Radio Access
Network
 The Controlling RNC has the overall control of a particular
set of cells, and their associated base stations.
10

Radio Network Controller
11

RNC Functions
• Radio resource management
 Code allocation
 Power Control
 Congestion control
 Admission control
• Call management for the users
• Connection to CS and PS Core
Network
• Radio mobility anagement
12

RADIO ACCESS BEARERS
 To establish a call connection between the handset
and the base station
 Its characteristics are different depending on what
kind of service/information to be transported.
 Carries the subscriber data between the handset and
the core network.
 It is composed of one or more RABs between the
handset and the Serving RNC, and one Iu bearer
between the Serving RNC and the core network.
13

Radio Access Bearers Quality classes
Conversational (used for e.g. voice telephony)
Low delay, strict ordering
Streaming (used for e.g. watching a video clip)
Moderate delay, strict ordering
Interactive (used for e.g. web surfing)
Moderate delay
Background (used for e.g. file transfer)
No delay requirement
14

CORE NETWORK (CN)
• Used for GSM with further elements overlaid to enable the additional functionality
demanded by UMTS.
• Provides all the central processing and management for the system.
•
• Similar to the network and switching subsystem (NSS) of the GSM architecture.
• Perform packet routing, connection of users, security, billing etc.
• Interfaces to external networks including the public phone network and other
cellular telecommunications networks
Circuit switched elements:
 Based on the GSM network entities and carry data in a circuit switched manner,
i.e. a permanent channel for the duration of the call.
Packet switched elements:
 These network entities are designed to 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.
15

UMTS Core Network
16

CIRCUIT SWITCHED CORE NETWORK
MOBILE SWITCHING CENTRE
(MSC)
 Interface between the RAN and
fixed networks.
 Mobility management
 Call control
 Switching functions services to
and from mobile stations.
GATEWAY MSC (GMSC)
 Interfaces with the fixed
networks
 Handles subscriber location
information from the HLR
 Performs routing functions to
and from mobile stations
17

PACKET SWITCHED ELEMENTS
• Routes packets of user data
independently of one another.
• No dedicated circuit is
established.
• Each packet can be sent along
different circuits depending on
the network resources available
Packet switched elements
 SGSN
 GGSN
 BG
18

SERVING GPRS SUPPORT NODE (SGSN)
Mobility Management
 When a UE attaches to the Packet Switched domain of the UMTS Core Network, the
SGSN generates MM information based on the mobile's current location.
Session Management
 The SGSN manages the data sessions providing the required quality of service
 Managing what are termed the PDP (Packet data Protocol) contexts, i.e. the pipes over
which the data is sent.
Interaction with other areas of the network
 The SGSN is able to manage its elements within the network only by communicating
with other areas of the network, e.g. MSC and other circuit switched areas.
Billing
 Monitoring the flow of user data across the GPRS network.
 CDRs (Call Detail Records) are generation.
 Transfer of CDRs to the charging entities (Charging Gateway Function, CGF).
19

GATEWAY GPRS SUPPORT NODE (GGSN)
 Central element within the UMTS packet
switched network.
 Inter-working between the UMTS PS network
and external packet switched networks
 Very sophisticated router
 It receives data addressed to a specific user,
it checks if the user is active and then
forwards the data to the SGSN serving the
particular UE
20

BORDER GATEWAY (BG)
Connectivity, and interworking and roaming
capabilities between two different PLMNs.
21

SHARED ELEMENTS 3G UMTS NETWORK
 HLR
 EIR
 AUC
 IN
 SMSC
 VLR
 BC
22

SHARED ELEMENTS 3G UMTS NETWORK
HOME LOCATION REGISTER (HLR)
 Administrative information about each subscriber
 Last known location of the subscriber
 Stores latest position with their current or last known location
VISITOR LOCATION REGISTER(VLR)
 Manages mobile subscribers of home PLMN and roaming
 The VLR exchanges information with the HLR.
EQUIPMENT IDENTITY REGISTER (EIR)
 Used for UE may be allowed onto the network.
 Each UE equipment has an unique number known as IMEI.
 IMEI checked during registration or LLocation updation.
AUTHENTICATION CENTRE (AUC)
 Protected database that contains the secret key of the user's USIM card.
SMS MSCS
 Transfer of messages between the SMSC and the PLMN.
23

ENHANCEMENT IN UMTS ARCHITECTURE IN
FUTURE RELEASES
Release 4
MSC is split in two as MSC server and CS-MGW
CS Media gateway (CS-MGW)
 Handles the traffic functions of the MSC
 Uses different transport protocols
 It also includes a media conversion function
MSC server
 Combines the signalling functions of the MSC with those of the VLR
 Controls the CS-MGW over a signalling interface that lies between them.
 GMSC server is built in the same way
Release 5
 IP multimedia subsystem (IMS) : provides real time packet switched services
 Home subscriber server (HSS) : combines the functions of the HLR and AuC
 IuFlex : RNC can be connected to multiple MSCs and multiple SGSNs.
Release 6
 WLAN interworking : Using WLAN access gateway (WAG) and packet data gateway
(PDG)
24

CONCLUSION
 WCDMA is very successful technology due to its
robust radio network design.
 By virtue of WCDMA and frequency reuse the
capacity and of WCDMA system is increased
tremendously.
 But with the introduction of Data on mobile
WCDMA has lost its shine as it deliveries very less
data rates.
 Thus WCDMA has been migrated to newer
technologies such as LTE and LTE Advance.
25

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UMTS Core Network and Elements

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