Introduction to WCDMA Fundamentals Nokia

WCDMA Technology andRadio Fundamentals

2 © Nokia Siemens Networks

Agenda

1. WCDMA Fundamentals– Introduction– WCDMA Network Architecture and Interfaces– Basic Concepts: Spreading, Processing Gain– WCDMA codes– Radio Fundamentals : RSCP, Ec/Io– WCDMA channels

2. WCDMA Network Dimensioning and Planning – WCDMA Network Dimensioning Process Overview– Cell Breathing Concept– Input Planning Parameters– Link Budget– 3G Planning : Key Results analysis

What 3G can offer to End Users..

Drivers for 3G

evolution

Drivers for 3G evolution and broadband mobile

Demand model

• Analogies from fixed broadband usage for both business and consumers

• Average DSL user consumes today 1-2 GB per month (data, voice, video)

Advances in acc. Tech. development

• Flarion, WiMax, 3GPP2 camp, WLAN

• Technology politics (e.g., Korea-US-Japan-China- Europe)

Changing service & underlying technology mix

• Refarming

• New spectrum

Spectrum and regulatory drivers

• Volume & ARPU shift from voice to data

• Circuit switched to packet data (VoIP, IMS)

• Internet as a major source for mobile services

Price/performanceof technology

• Efficient use of spectrum

• Improved broadband experience

GSM evolution to 3G

GSM9.6kbps (one timeslot)GSM DataAlso called CSD

General Packet Radio ServicesData rates up to ~ 115 kbpsMax: 8 timeslots used at any one timePacket switched; resources not tied up all the timeGSM / GPRS core network re-used by WCDMA (3G)

High Speed Circuit Switched DataDedicate up to 4 timeslots for data connection ~ 50 kbpsGood for real-time applicationsInefficient -> ties up resources, even when nothing sent

Enhanced Data Rates for Global EvolutionUses 8PSK modulation3x improvement in data rate on short distancesCan fall back to GMSK for greater distancesCombine with GPRS (EGPRS) ~ 384 kbpsWCDMA

New services demand higher speed

Non-real time background and

narrowband streaming

Interactive, medium bit rate

streaming, business

connectivity

Real time connections,

efficient business connectivity

HSPA1-14Mbps

WCDMA128-384

EDGE80-160kbps

GPRS30-40kbps

GSM10-40kbps

Video sharingVideo

telephonyReal time IP

Real time games

High speed mobile

intranet

Faster business

connectivityFaster

streamingFaster

content downloadWeb browsing

Mobile intranet accessVideo

streamingVideo sharingVoice

MMSWAP

DownloadPresence

Audio streaming

Close to WLAN bit rates and

high efficiency

What can be done to meet Demands

GSMWCDMA

Flarion Flash-OFDMBWA

WiMAX (802.16-2005)

NxEV-DO

3.9 G HSPA

EV-DO rev. A, Rev B

I-HSPA

UMTS-TDD

WLAN (unlicensed)

EDGE Evolution

WiMAX (802.16-2004)

Mobile

’05 ’06 ’07 ’08 ’09 ’10

Standardisation of 3G Cellular Networks

Standardisation of 3G cellular networks

ITU (Global guidelines and recommendations)• IMT-2000: Global standard for third generation (3G) wireless communications

3GPP is a co-operation between standardisation bodiesETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA (South Korea)

• GSM, EDGE• UMTS

– WCDMA - FDD– WCDMA - TDD

3GPP2 is a co-operation between standardisation bodies

ARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea)• CDMA2000

– CDMA2000 1x– CDMA2000 1xEV-DO

Structure of 3GPP

TSG STRUCTURE

UMTS Release 99

UMTS Release 4

UMTS Release 5

UMTS Release 6

• UMTS CN• UTRAN & WCDMA

• Low chip rate TDD mode

• High Speed Downlink Packet Access (HSDPA)• Wideband AMR• Initial phase of the IP Multimedia Subsystem• IP transport in the UTRAN etc.

• FDD Enhanced Uplink (HSUPA)• IMS Phase 2• Wireless LAN/UMTS Inter-working• Multimedia Broadcast/Multicast Service (MBMS)

19992001

UMTS Releases

UMTS Release 7• 64 QAM modulation• MIMO• HSPA+

UMTS Release 8 • LTE

Downlink peak rate

Network Latency

Uplink peak rate

Bandwidth

Standard

3G evolution – performance

Spectral efficiency, DL

Spectral efficiency, UL

WCDMA R99

5.0 MHz

100-200 ms

384 kbps

0.16 bps/Hz

WCDMA HSPA

5.0 MHz

<50 ms

1.8-10.7 Mbps

1-4 Mbps

0.2-0.8 bps/Hz

0.25 bps/Hz

3.9 G estim.

1.25-20 MHz

<10 ms

Up to 100 Mbps

Up to 50 Mbps

1.6-2.5 bps/Hz

0.6-0.8 bps/Hz

Market Trends for 3G Technology

World Cellular Market

Global growth of UMTS HSPA Technology

UMTS HSPA Networks Worldwide

Technology Forecast

Subscriber Forecast

Data Rate Evolution

•3G Rollout in India has already been delayed due to various reasons.

•Operators are taking time before committing themselves for such a Hugh investments.

•The way Indian Mobile Industry is growing, there is definitely need for a more spectrum efficient technology – 3G is the right choice for that

•Tentative timeline for initial rollout looks like to be sometime this year then 2010 will be the year when many more rollout may take place.

Future of 3G in India – The Question!!!!!

Indian Wireless Market

GSM market share to increase from 73% in 2008 to 79% in 2013

Indian Subscriber growth and pattern

3G and BWA Subscribers in India

Application Usage Pattern

GSMGSM GSM WCDMA

CDMAIS-95A

CDMACDMA

IS-95B

1xRTT 1xEV-DO 1xEV-DVCDMA2000

2G 2.5G 3G

Multiple phases

Focus of this Workshop

The Roads to 3G

WCDMA Network Architecture and Interfaces

UMTS NW Architecture

User Equipment(UE)

IurIub

WCDMA BTS

Core Network

Interfaces of UMTS System

Circuitswitched

(cs) domain

packetswitched

(ps)domain

Radio Network Subsystem (RNS)

MSC/VLR

General UE Architecture

Mobile Equipment

UMTS SIM

UTRANTerminal

Equipment

General UTRAN Architecture

Node B

Radio Network Controller

CN (MSC)

CN (SGSN)

Elements of UTRAN

Radio Network Controller

• Owns and controls radio resources in its domain (BSC in GSM)

• Service Access Point for all services that UTRAN provides for the CN

• Note: Service RNC (SRNC) and Drift RNC (DRNC) are subsets

Node B

• Acts as the radio base station (BTS in GSM)

• Converts the data flow between the Iub and Uu interfaces

Major Interfaces in UMTS

There are four major new interfaces defined in UMTS

• Iu

– The interface between UTRAN and the CN

• Iur

– The Interface between different RNCs

• Iub

– The interface between the Node B and the RNC

• Uu

– The air interface

Node-B

Iu - the Core Network to UTRAN Interface

There are two parts to the Iu interface

• Iu-ps connecting UTRAN to the PS Domain of the CN

• Iu-cs connecting UTRAN to the CS Domain of the CN

No radio resource signalling, travels over this interface

• The Iu interface divides the UMTS network into the radio specific UTRAN and the CN.

Node-B

Iur - the Inter-RNC Interface

The Iur interface allows soft handovers between Node-Bs attached to different RNCs

It is an open interface to allow the use of RNCs from different manufacturers

Its functions may be summarised:

• Support of basic inter-RNC mobility

• Support of Dedicated and Common Channel Traffic

Node-B

Iub - the RNC to Node-B Interface

The Iub is an open interface to allow the support of different manufacturers supplying RNCs and Node-Bs

Its major functions are:

• Carries dedicated and common channel traffic between the RNC and the Node-B

• Supports the control of the Node-B by the RNC

Node-B

Uu - the Air Interface

Clearly the Uu must be standardised to allow multiple UE vendors to be supported by a network

The major functions of the Uu are to:

• Carry dedicated and common channel traffic across the air interface

• Provide signaling and control traffic to the mobile from the RNC and the Node-B

Node-B

WCDMA Services

UMTS QoS Classes

UMTS attempts to fulfil QoS requests from the user

Four traffic classes have been specified

• Conversational

• Streaming

• Interactive

• Background

Main distinguishing feature is delay sensitivity

QoS Classes

Telephony

Videotelephony

Filedownloading

Webbrowsing

Maildownloading

Calendersynchronisation

Teleworking

Teleshopping

Streamingvideo

Streamingmusic

Conversational Class

•Conversational pattern - symmetric

•Real time, Extremely delay sensitive

•Typically between peers

•Example Applications:– Voice

– Video telephony

Streaming

•Highly asymmetric

•Real time, relatively low delay required

•Typically between server and client

•Example Applications– Web broadcast

– Video on demand

– Streaming multimedia

Interactive

•Request response pattern

•Preserve data integrity

•Relatively delay sensitive but not real time

•Treated as non-real time packet based service

•Example applications:– Web browsing

– Location based services

– Database retrieval

Background

•Destination is not expecting the data within a certain time

•Preserve data integrity

•Treated as non-real time packet based service

•Example Applications– Download of Emails

– File download

Basic Concepts of WCDMA- Radio

UMTS Air Interface Technical Aspects

Access Technology Explanation

Multiple Access means “Many users share the same medium”

There are a number of different Multiple Access (MA) strategies :

• Time Division Multiple Access (TDMA)

• Frequency Division Multiple Access (FDMA)

• Code Division Multiple Access (CDMA)

User 1 User 1

Timeslot Period Frame Period

Idealised TDMA (with no guard periods)

Available Frequency Band

User 1

Frame Period (we may still need frames/timeslots for signaling)

Channel Bandwidth

Idealised FDMA (with no guard bands)

CDMA - Direct Sequence Spread Spectrum

Frame Period (we may still need frames/timeslots for signaling)

WCDMA Technology

3.84 M Hz

5+5 MHz in FDD mode5 MHz in TDD mode

TimeDirect Sequence (DS) CDMA

WCDMA Carrier

WCDMAWCDMA5 MHz, 1 carrier5 MHz, 1 carrier

TDMA (GSM)TDMA (GSM)5 MHz, 25 carriers5 MHz, 25 carriers

Users share same time and frequency

UMTS & GSM Radio Network Planning

GSM900/1800: 3G (W CDM A):

Concepts of Spreading in WCDMA

Spreading

Bits, Chips and Spreading Factor

• Each user data bit is multiplied with a sequence of 'x' code bits called CHIPS.

•Data bits when spreaded with code sequence is known as chips

DataBit rate

Spreading Code

chip rate

In order to distinguish between the information-carrying bits in the

user data and the bits in the user spreading codes, we tend to use the term ‘chips’ to refer to the bits in the spreading code

Bits, Chips and Spreading Factor

• Each user data bit is multiplied with a sequence of 'x' code bits called CHIPS.

•Data bits when spreaded with code sequence is known as chips

Example:

Spreading code 1 = (1, -1)

Data to spread = (1,0,1,1)

• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1 = (1,-1, -1,1,1-1,1,-1)

Spreading factor (SF) = Spreaded Signal BW / Unspreaded Signal BW

= The number of chips per data

• In the above example : SF= 8/4 = 2

DataBit rate

Spreading Code

chip rate

Spreading and Despreading

SpreadingEach user data bit is multiplied with a sequence of 'x' code bits called CHIPS. This 'x' determines the SPREADING FACTOR!!!!

The resulting spread data is at a rate of 'x' times user data rate

DespreadingThe spread user data/chip sequence is multiplied with the same 'x' code chips to recover the original data.

Example:

Data to spread = (1,0,1,1)

• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1

= (1,-1, -1,1,1-1,1,-1)

• Despreading : Multiply the received signal with same spreading code

• ( 1, -1, -1, 1, 1, -1, 1, -1).(1,-1)– 1. Take first two chips = (1,-1).(1,-1) = 1+1 = 2 = +ve => 1

– 2. Take next two chips = (-1,1).(1,-1) = -1 -1 = -2 = -ve => 0

– 3. Take next two chips = (1,-1).(1,-1) = 1+1 = 2 = +ve => 1

– 4. Take next two chips = 1,-1).(1,-1) = 1+1 = 2 = +ve => 1

Spreading

Frequency

Unspread narrowband signal Spread wideband signal

Bandwidth W (3.84 Mchip/sec)

User bit rate R

WdBGp Processing

Spreading & Processing Gain

• Spreading Operation helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during transmission

Frequency (Hz)

Voice user (R=12,2 kbit/s)

Packet data user (R=384 kbit/s)

Frequency (Hz)

Gp=W/R=24.98 dB

Gp=W/R=10 dB

• Spreading sequences have a different length• Processing gain depends on the user data rate

Example

WCDMA Spreading and Scrambling Operation

In WCDMA two separate codes are used in the spreading operation

• Channelisation code (spreading code)

• Scrambling code

Bit rate

Chanelization code (SF)

scrambling code

chip rate chip rate

WCDMA CodesIn WCDMA two separate codes are used in the spreading operation

– Channelisation code

– Scrambling code

Scrambling code– DL: separates cells in same carrier frequency

– UL: separates users

Channelisation code– DL: separates different users within a cell

– UL: separates physical channels of one user

DL Spreading and Scrambling in WCDMA

User 1 Signal

Channlisation code 1

Channelisation Code 2

SCRAMBLINGCODE

3.84 MHzRF carrier

3.84 MHz bandwidth

CHANNELISATION codes:

User 2 Signal

User 3 Signal

Node B

UL Spreading and Scrambling in WCDMA

User 1 Signal

Channlisation code 1

Scrambling Code 1

User 2 Signal

User 3 Signal

Scrambling Code 2

Scrambling Code 3Scrambling Code 3RF

Node B

DL Spreading and Multiplexing in WCDMA

User 3

User 2

User 1

Pilot X

CODE 1

CODE 2

CODE 3

CODE 4

CODE 5

SCRAMBLINGCODE

User 2

User 1

Radio frame = 15 time slots

User 3

3.84 MHzRF carrier

3.84 MHz bandwidth

P-CPICH

P-CCPCH

Property of the Chanalization (Spreading) Codes

Orthogonality

Two codes are said to be orthogonal when their inner product is zero.

Let: let S1 be one SF code & S2 another

• Then : S1* S2 = 0

Eg:(1, 1, 1, 1) and (1, 1, -1, -1) are orthogonal:

(1 * 1) + (1 * 1) + (1 * -1) + (1 * -1) = 0

Orthogonal spreading code Tree & Generation

SF = 1 SF = 2 SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)

Top sub-element

Bottom sub-element

Channelisation Code Tree

C0(0)=[1]

C2(1)=[1-1]

C2(0)=[11]

C4(0)=[1111]

C4(1)=[11-1-1]

C4(2)=[1-11-1]

C4(3)=[1-1-11]

C8(0)=[11111111]

C8(1)=[1111-1-1-1-1]

C8(2)=[11-1-111-1-1]

C8(3)=[11-1-1-1-111]

C8(0)=[1-11-11-11-1]

C8(5)=[1-11-1-11-11]

C8(6)=[1-1-111-1-11]

C8(7)=[1-1-11-111-1]

C16(0)=[............]C16(1)=[............]

C16(15)=[...........]

C16(14)=[...........]

C16(13=[...........]

C16(12)=[...........]

C16(11)=[...........]

C16(10)=[...........]

C16(9)=[............]

C16(8)=[............]

C16(7)=[............]

C16(6)=[............]

C16(5)=[............]

C16(4)=[............]

C16(3)=[............]

C16(2)=[............]

SF=256

SF=512

Example

Date to spread = (1,0,1,1)

• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1 = (1,-1, -1,1,1-1,1,-1)

Spreading code 2 = (1,1)

Date to spread = (0,0,1,1)

Data after spreading = (-1,-1, -1,-1, 1,1, 1,1 )

Combined signal = (1,-1,-1,1,1,-1,1,-1) + (-1,-1,-1,-1,1,1,1,1) = (0,-2,-2,0,2,0,2,0)

User 1 decodes it by simple vector multiplication

(0,-2, -2,0, 2,0, 2,0) . (1,-1)

1. Take first 2 bits = (0,-2).(1,-1) = (0).(1) + (-2).(-1) = 0+ 2 = 2 => +ve => 1

2. Take next 2 bits = (-2,0).(1,-1) = (-2).(1) + (0).(-1) = -2+0 = -2 => -ve => 0

3. Take next 2 bits (2,0).(1,-1) = 2.1 + 0.-1 = 2 + 0 = 2 => =+ve => 1

4. Take next 2 bits (2,0).(1,-1) = 2 => +ve => 1

That way all 4 bits are retrieved at the receiver side.

Multipath and Rake Receiver

Multipath Propagation

Scrambling code

Operation in Multipath Environment

Radio propagation is characterized by multipath propagation which may result into attenuation of signal energy

Operation in Multipath environment/Rake reception

Rake ReceptionWCDMA requires some countermeasures against Fast fading!!!!The solution is RAKE RECEIVER!!!!!

So what is a RAKE RECEIVER????

Fading????!!!

Fingers??!!

Spreading/Despreading???!!!

Rake Receiver

•A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" called fingers, each assigned to a different multipath component

Multipath components are delayed copies of the original transmitted wave traveling through a different path, each with a different magnitude and time-

of-arrival at the receiver

Since each component contains the original information, if the magnitude and time-of-arrival (phase) of each component is computed at the receiver (through a process called channel estimation), then all the components can

be added coherently to improve the information reliability. This could very well result in higher signal-to-noise ratio (or Eb/N0) in a multipath environment

RAKE Receiver

RAKE RECEPTION

Operating Principle of Rake Receiver Assign a RAKE finger to each time delay position where significant energy arrives. Within each correlation receiver track the fast changing phase and amplitude

Transmitted symbol Received signal at each time delay Modified with channel estimate Combined Symbol

finger1

finger2

finger3

UMTS Bearers

AMR 12.2AMR 12.2

Transparent CS data 64Transparent CS data 64

Non-transparent CS data 14.4, 57.6Non-transparent CS data 14.4, 57.6

NRT PS data 8, 16, 32, 64, 128, 256, 384 (UL/DL) (CELL_DCH)NRT PS data 8, 16, 32, 64, 128, 256, 384 (UL/DL) (CELL_DCH)

NRT PS data 16 (UL), 32 (DL) (CELL_FACH)NRT PS data 16 (UL), 32 (DL) (CELL_FACH)

Streaming PS data 8, 16, 32, 64, 128, 256 (DL)Streaming PS data 8, 16, 32, 64, 128, 256 (DL)

Lower AMR speech codecs: 7.95, 5.90, 4.75 , 12.65, 8.85, 6.6Lower AMR speech codecs: 7.95, 5.90, 4.75 , 12.65, 8.85, 6.6

Concepts of RSCP and Ec/No

Two Important Terms

• RSCP

• Ec/No, Ec/Io

Scrambling Codes & CPICH

The Common Pilot Channel (CPICH) is broadcast from every cell

It carries no information and can be thought of as a “beacon” constantly transmitting the Scrambling Code of the cellWCDMA cells are identified by their SC.

Its like a BCCH in GSM

It is this “beacon” that is used by the phone for its cell measurements for network acquisition and handover purposes (Ec, Ec/Io).

Total Received Power Io

In a WCDMA network the User Equipment (UE) receives signals from many cells

Io* = The sum total of all of these signals (dBm)

*Note: Sometimes Io is referred to as No, RSSI

Received Power of CPICH : RSCP

Using the properties of SCs the UE is able to extract the respective CPICH levels from the sites received

RSCP = The Received Power of a Particular CPICH (dBm)

Ec = Energy per Chip

RSCP 1 RSCP 2

CPICH Quality (Ec/Io)

IoRSCP

From the previous two measures we can calculate a signal quality for each CPICH (SC) received

Ec/Io = (Energy per chip / Noise spectral density) = RSCP/RSSI

*Note: Sometimes Ec/Io is referred to as Ec/No

Relation between Ec/Io and Eb/No

Handover Types

Intra-Frequency HandoversSofter HandoverSoft HandoverHard Handover

Inter-Frequency Handover• Can be intra-BS, intra-RNC, inter-RNC

• Decision algorithm located in RNC

Inter-RAT Handover • Handovers between GSM and WCDMA

Handovers - Softer Handover

• Handover between sectors of the same Node B (handled by BTS)• No extra transmissions across Iub interface• Maximum Ratio Combining (MRC) is occurring in both the UL and DL

Handovers - Soft Handover

• MS simultaneously connected to multiple cells (from different Node Bs)• Extra transmission across Iub, more channel cards are needed (compared

to non-SHO)• Mobile Evaluated Handover (MEHO)• DL/UE: MRC & UL/RNC: Frame selection combining

Handovers - Inter frequency HO

Inter frequency handover occurs between two WCDMA carriersWill be used once operator deploys its second carrier

Handovers - Inter system HO

Inter system handover occurs between 3G and 2G sitesAs with all handovers, accurate adjacencies will be required

Handover types

Soft Handover

Hard/Inter-Frequency Handover

Inter-System Handover

Node B

Frequencyf1

Frequencyf2

UMTS GSM900/1800

Frequencyf1

RNC RNC

Iub Iub

Node B

Node B Node B

Node BNode B

Softer Handover

Sector 1f1

Sector 2f1

Sector 3f1

Sector 1

Sector 3

Node B

Node B BTS

Air Interface Channels

WCDMA Frame

• Radio frame: A radio frame is a processing duration which consists of 15 slots. The length of a radio frame corresponds to 38400 chips.

• Slot: A slot is a duration which consists of fields containing bits. The length of a slot corresponds to 2560 chips

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Air Interface Access Stratum

Radio Resource

Control RRC

Radio Link Control RLC

Medium Access

Control MAC

Physical Layer

Control Plane Signalling

User Plane Information

Logical

Channels

Transport Channels

Physical Channels

UMTS Channel Types and Functions

There are three types of channel across the air interface and access stratum that we are interested in:

• Logical Channels

– Between the RLC and MAC layers

– What kind of data is transmitted

• Transport Channels

– Between the MAC and Physical layers

– How data is transmitted – characteristics of data transmission

• Physical Channels

– Between Physical Layers at the Node-B and UE

– Actual transmission/reception of data

Logical Channelscontent is organised in separate channels, e.g.

System information, paging, user data, link management

Transport Channelslogical channel information is organised on transport channel

resources before being physically transmitted

Physical Channels(UARFCN, spreading code)

FramesIub interface

Radio Interface Channel Organisation

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

LogicalChannels

TransportChannels

PhysicalChannels

Channel Mapping DL (Network Point of View)

HS-SCCH

DCH DPDCHDTCH

LogicalChannels

TransportChannels

PhysicalChannels

RACHCCCH PRACH

Channel Mapping UL (Network Point of View)

HS-DPCCH

Logical Control Channels

The Broadcast Control Channel (BCCH) is a downlink channel for broadcasting system control information

The Paging Control Channel (PCH) is a downlink channel that transfers paging information

The Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel transmitting control information between a specific UE and the UTRAN

The Common Control Channel (CCCH) is a bi-directional channel transmitting control information between UEs and the UTRAN

P-CCPCH

P-CPICH

S-SCHP-SCH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

Logical Traffic Channels

The Dedicated Traffic Channel (DCH) is a point-to-point channel dedicated to a single UE for the transfer of user information

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

Common Transport Channels

The Broadcast Channel (BCH) is a cell-wide channel that is used to broadcast system and cell-specific information. The BCH is always transmitted over the entire cell with a low fixed bit rate.

The Paging Channel (PCH) is a cell-wide channel that is used to carry control information to a UE when the system does not know the location cell of the UE

The Forward Access Channel (FACH) is a downlink channel that is used to carry control information to a UE when the system knows the location cell of the UE. May also carry short user packets.

The Random Access Channel (RACH) is an uplink control channel from the UE. May also carry short user packets

P-CCPCH

P-CPICH

S-SCHP-SCH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

Dedicated Transport Channels

The Dedicated Channel (DCH) is a channel dedicated to one UE used in uplink or downlink.

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

The Primary-Common Control Physical Channels (P-CCPCH) is used to carry broadcast information across the cell

The Secondary-Common Control Physical Channels (S-CCPCH) is used to carry paging and forward access information across the cell

The Primary-Synchronisation Channel (P-SCH) is used during cell search to provide timing information

The Secondary-Synchronisation Channel (S-SCH) is used during cell search to provide information about the primary scrambling codes in use in the cell

The Common Pilot Channel (CPICH) is used to provide the phase reference for downlink channels

The Acquisition Indicator Channel (AICH) is used to acknowledge random access requests

Common Physical Channels for UMTS

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

The Paging Indicator Channel (PICH) is used to enable discontinuous reception of the S-CPCCH

The Physical Random Access Channel (PRACH) is a contention based channel used for random access and to transmit small packets of information

The Physical Common Packet Channel (PCPCH) is an extension to the RACH used to carry larger packets of information on the uplink

The Access Preamble Acquisition Indicator Channel (AP-AICH) is used to indicate the reception of a preamble signature for Random Access

Common Physical Channels for UMTS

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

Dedicated Physical Channels for UMTS

The Dedicated Physical Data Channel (DPDCH) is used to carry user information

The Dedicated Physical Control Channel (DPCCH) is used to carry dedicated control information regarding its associated DCHs

P-CCPCH

P-CPICH

P-SCHFACH

HS-DSCH

HS-PDSCH

S-CCPCH

HS-SCCH

DL Common Control Channel

Most common channel have fixed configuration and power

• CPICH

• P-CCPCH

• P-SCH, S-SCH

• AICHSetting the DL Common Control Channel Power is a trade off between:

• cell coverage: all the channels must be decoded at the cell edge

• cell capacity: the common channel power consume resources from the traffic channels

Pilot Channel Power Setting

By default the CPICH consumes 2 W of the Node B power (20 W PA)

• For 40 W PA default is 4 W (10 %)CPICH power is used to derive the power requirements of the other Common Control Physical Channels (CCPCH)

The CPICH should be tuned on a per carrier per area basis as part of wide area parameter tuning following the radio network planning activity

Adjust CPICH transmit Power

Identify Cells with poor coverage

Identify Cells with excessive coverage

Evaluate Ec/Io and RSCP

performance

DL Common Control Channel

DL Common Channels does not have a power control.

The power of the common physical channels are set relative to the CPICH

Effect of CPICH Power modification

CPICH Transmit Power

Increased soft handover overhead

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handover

Increased Eb/No requirement

Reduced system capacity

Reduced system coverage

Slow initial synchonisation

Non-ideal traffic distribution

Late cell reselection /handover

CPICH Transmit Power

Increased soft handover overhead

Too much

Too little power

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handout too early

Increased Eb/No requirement

Reduced system capacity

Reduced system coverage

Slow initial synchonisation

Late cell reselection /handout too late

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