3G STANDARDS OVERVIEW &

RADIO ACCESS NETWORK ARCHITECTURE

Basic of 3G technologies

3G standards overview

Reasons to switch from 2G to 3G

The main advantage of 3G technology is that is has much higher data rate (384kbps up to 2 Mbps).

3G technology offers a high level of security as compared to 2G technology.

3G technologies provide improved telephone service and significantly increased system capacity.

3G data speed

Second-generation systems only provide speeds from 9.6 kbit/s to 28.8 kbit/s.

WCDMA is commonly operated on the Channel Bandwidth 5 MHz And 384kbps bit rate.

High Speed Packet Access (HSPA) is an amalgamation of High Speed Downlink Packet Access (HSDPA) can support down-link speeds of up to 42.3 Mbit/s and High Speed Uplink Packet Access (HSUPA) can support up-link speeds of up to5.76 Mbit/s.

HSPA+ can support 168  (Mbit/s) to the mobile device (downlink) and 22 Mbit/s from the mobile device (uplink)

Background on UMTS

December 1, 2001 Telenor launched in Norway the first commercial UMTS network.

December 19, 2001 Nortel Networks and Vodafone in Spain completed first live international UMTS 3GPP standard roaming calls between Madrid (Vodafone network) and Tokyo (J-Phone network).

January 31, 2003 Ericsson conducts the world's first IPv6 over 3G UMTS/WCDMA network demonstration.

December 16, 2004 (Freeze date) UMTS Release 6

History on development towards WCDMA

Since 1985, ITU (International Telecommunications Union) has been developing IMT-2000, previously termed Future Public Land Mobile Telephone System (FPLMTS).

In 1992, the World Administrative Radio Conference (WARC) of the ITU identified the frequencies around 2 GHz for future 3rd generation mobile systems, both terrestrial and satellite.

Within the ITU, the 3rd generation systems are called International Mobile Telephony 2000 (IMT-2000). In Europe, it is called UMTS (Universal Mobile Telephone Service).

Radio Access Network Architecture

UMTS-3G Network Architecture Block is given below

Comparison between 2G and 3G structure

UE (User Equipment)

The UE is the hardware that a user uses to access the network. Example- Mobile.

It is consisted of ME (Mobile Equipment) and USIM(UTMS subscriber identity module).

The USIM is a smartcard that holds the subscriber identity, performs authentication algorithms, and stores authentication and encryption keys and some subscription information that is needed at the terminal.

UE (User Equipment)

Node B

Communicates directly with UE. Is controlled by an RNC (Radio Network

Controller).Sends voice information and data and control

signaling to the UE(User Equipment).Assigns and maintains the voice channels

through which the UE communicates with another user. 

Node B

RNC (Radio Network Controller)

Controls Node B.Provides Soft hand-off.Manages radio channels and the terrestrial

channels.Each RNC is connected to a SGSN the

packet switched part of the core network through the Iu-ps interface, thus provides internet usage option to the UEs. 

RNC (Radio Network Controller)

MSC (Mobile switching Centre)

Works as a normal switching node. Inter-MSC handovers and Call routing to a

mobile subscriber.Provides an interface to the PSTN so that calls

can be routed from the mobile network to a phone connected to a landline.

HLR (Home Location Register)

HLR is a central database that contains details of each mobile phone subscriber that is authorized to use the GSM core network.

The HLRs store details of every SIM card issued by the mobile phone operator.

VLR (Visitor Location Register)

It informs the HLR that a subscriber has arrived in the particular area covered by the VLR.

Tracks where the subscriber is within the VLR area (location area) when no call is ongoing.

Allows or disallows which services the subscriber may use.

GMSC (Gateway Mobile Switching Center)

Find and interrogate HLR for roaming number.

Route the call according to the interrogation.Enable calls to be made to mobiles on

different networks

SGSN (Serving GPRS Support Node)

Delivers data packets from and to the mobile stations within its geographical service area.

Packet routing and transfer, mobility management, logical link management, and authentication and charging functions.

GGSN (Gateway GPRS Support Node)

The GGSN is responsible for the internetworking between the GPRS network and external packet switched networks.

Mobile-originated packets are routed to the right network by the GGSN.

The GGSN converts the GPRS packets coming from the SGSN into the appropriate packet data protocol (PDP) format

External networks

An external network consists of:PSTN (Public Switched Telephone Network)

PLMN (Public Land Mobile Network)

ISDN (Integrated Services for Digital Network)

Internet

PSTN, PLMN, ISDN etc are connected with the GMSC (Gateway MSC) of the core network.

How these all elements are connected in a way to establish a call?

Mobile to Mobile:

Mobile to Mobile under different network

Mobile to PSTN:

UE’s Use of Internet:

Network Architecture

Physical layer- Sending bits through physical medium Error detection , channel coding, modulation Data link layer- Appropriately framing the message Providing the mechanism of sharing the medium Medium access(MAC)layer Network layer- Routing over the subnets Congestion control To provide communication over asymmetric networks Transport layer- End to end data recovery Flow control Ensuring complete data transfer Application layer- The interface with the user for an application Email, FTP HTTP

WCDMA OSI model

Logical channels(What is transmitted)

Transport channels(How it is transmitted)

Radio Resource Control (RRC)

Physical Layer

Medium Access Control (MAC)

RLC RLC RLC

Physical channels(Code,frequency,etc)

WCDMA OSI MODEL

Layer 1-Physical layer This layer is responsible for transporting data across the

available physical path (radio link). Layer 2-Datalink layer It is the upper neighbor of the physical layer. 3GPP

divides it into the radio link control (RLC) and the medium access control (MAC) layer. It delivers data block by block to layer 1 via transport channels (or fetches the data when receiving).

Layer 3-Network layer It is also known as RRC layer.RRC layer is directly above

the layer 2 and is responsible for radio resource control.

What is a Femtocell?

Mobile phone base station for home/officeConnects via broadband internetProvides excellent capacity/coverage

What problems do they solve?

coverage

capacity

Area

What types of Femtocell are there?

DOMESTIC

ENTERPRISE

METRO-FEMTO

How do they work?

Some technical issues of FemtoCell

Interference The placement of a femtocell has a critical effect on the

performance of the wider network, and this is one of the key issues to be addressed for successful deployment.

Emergency callsAccess control There are issues in this regard for access point

base stations sold to consumers for home installation, for example. Further, a consumer might try to carry their base station with them to a country where it is not licensed.

Handover

ANTENNA SUBSYTEM TYPES

Cell splitting: subdividing a congested cell into smaller cells each with its

own base station . Cell splitting increases the capacity of cellular. It increases the number of times the channel are reused

microcell

ANTENNA SUBSYTEM TYPES

Sectoring: The sectoring is done by replacing a single Omni-directional

antenna with 3 directional antennas(120sectoring)or with 6 directional antennas(60sectoring)

Achieves capacity improvement by essentially rescaling the system.

less co-channel interference, number of cells in a cluster can be reduced

Larger frequency reuse factor, larger capacity.

3G UMTS frequencies

We see that there are 15 slots in a frame and each slot time, Ts = .667ms. There are 2560 chips in each slot.

UMTS time slot:

UMTS has several different time slot configuration depending on the used channel.

UMTS Channels

There are three types of channel in WCDMA. They are:

Logical channels.Transport channels.Physical channels.

UMTS Interfaces

Cu Interface: this is the electrical interface between the USIM smartcard and the ME.

Uu Interface: this is the WCDMA radio interfaceIu Interface: this connects UTRAN to the CN.Iur Interface: the open Iur interface allows soft

handover between RNCs from different manufacturers.

Iub Interface: the Iub connects a Node B and an RNC.

UMTS Quality of service(QoS)

What is QoS ?

Quality of Service (QoS) in cellular networks is defined as the capability of the cellular service providers to provide a satisfactory service which includes voice quality, signal strength, low call blocking and dropping probability, high data rates for multimedia and data applications etc.

UMTS Link Budget

What is link budget ?

Link budget planning is part of the network planning process, which helps to dimension the required coverage, capacity and quality of service requirement in the network.

A simple link budget equation looks like this:

Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) − Losses (dB)