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    HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

    Security Level:

    www.huawei.com

    WCDMA Fundamentals

    2008-10-23

    http://www.huawei.com/http://www.huawei.com/
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    HUAWEI TECHNOLOGIES CO., LTD. Page 2Huawei Confidential

    Contents

    n Overview of WCDMA

    n Handover Introduction

    n Power Control Introduction

    n UMTS Channels and Function

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    HUAWEI TECHNOLOGIES CO., LTD. Page 3Huawei Confidential

    Different Technologies for Different ServicesDifferent Technologies for Different Services

    AMPS

    TACS

    NMT

    GSMGSM

    CDMACDMA

    IS95IS95

    TDMATDMA

    IS-136IS-136

    PDCPDC

    1st

    generation in 1980sAnalog

    2nd

    generation in 1990sDigital 3rd

    generationIMT-2000

    UMTSUMTS

    WCDMAWCDMA

    cdmacdma

    20002000

    Driven bydemands

    Driven bydemands

    Analog

    te

    chnology

    Digitaltechnology

    Speec

    hservice

    Broadba

    nd

    service

    TD-SCDMA

    TD-SCDMA

    3G provides perfect solutions to integrated services for users and operators.

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    HUAWEI TECHNOLOGIES CO., LTD. Page 4Huawei Confidential

    UTRAN in UMTS Network

    Iu-BC

    RNC

    RNC

    NodeB

    NodeB

    NodeB

    CS

    PS

    CBC

    UE UTRAN CN

    Uu Iu

    Iu-CS

    Iu-PS

    Iu-BC

    Iur

    Iub

    Iub

    Iub

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    HUAWEI TECHNOLOGIES CO., LTD. Page 5Huawei Confidential

    Traffic channels: differentusers are assigned uniquecode and transmitted overthe same frequency band,for example, WCDMA andCDMA2000

    Traffic channels: different frequency bandsare allocated to different users,for example, AMPS

    Traffic channels: different time slotsare allocated to different users,for example, GSM

    Multiple Access TechnologyMultiple Access Technology -- DistinguishDistinguish Different UsersDifferent Users

    Frequency

    Time

    TDMATime

    Frequency

    FDMA

    Frequency

    Time

    CodeCDMA

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    HUAWEI TECHNOLOGIES CO., LTD. Page 6Huawei Confidential

    Basic Diagram of the WCDMA System

    Sourcecoding

    Channel

    coding andinterleaving

    ScramblingSpreading ModulationRF

    transmission

    Source

    decoding

    deinterleavingChannel

    decoding and

    de-interleaving

    De-scramblingDe-spreading DemodulationRF

    reception

    Radio link

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    HUAWEI TECHNOLOGIES CO., LTD. Page 7Huawei Confidential

    Common Termsl Bit, symbol and chip

    [ Bit (bps): the data that is obtained upon source coding and containsinformation.

    [ Symbol (sps): the data obtained upon channel coding and interleaving.

    [ Chip (cps): the data obtained upon final spreading.

    The spreading rate of WCDMA is: 3.84 Mcps

    l Processing gain

    [ It refers to the ratio of the final spreading rate to the bit rate (cps/bps).

    [ In the WCDMA system, the processing gain depends on the specific service.

    For example, for the 12.2 Kbps voice service, its processing gain is as follows:

    10*log10 (3.84 Mcps/12.2 Kbps) =10*log10314.75=25 db

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    HUAWEI TECHNOLOGIES CO., LTD. Page 8Huawei Confidential

    Spreading Factor and Service Rate

    l Chip rate = symbol rate spreading factor

    [ For WCDMA, if the chip rate is 3.84 MHz and the spreading factor is 4, the

    symbol rate is 960 Kbps.

    [ For CDMA2000-1x, if the chip rate is 1.2288 MHz and the spreading factor is

    64, the symbol rate is 19.2 Kbps.

    l Symbol rate = (service rate + check code) channel code

    repetition or punching rate

    [ For WCDMA, if the service rate is 384 Kbps and the channel code is 1/3

    Turbo, the symbol rate is 9.60 Kbps.

    [ For CDMA2000-1x, if the service rate is 9.6 Kbps and the channel code is

    1/3 convolutional code, the symbol rate is 19.2 Kbps.

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    HUAWEI TECHNOLOGIES CO., LTD. Page 9Huawei Confidential

    Source Coding

    l The WCDMA system adopts the adaptive multi-rate (AMR) speech coding.

    [ A total of eight coding modes are available. The coding rate ranges from 12.2

    Kbps to 4.75 Kbps.

    [ The system automatically adjusts the voice rate according to the load & distance

    between the user and the NodeB, thus reducing the number of handovers and

    call drop.

    Channel Coding

    l

    Channel coding can enhance symbol correlation to recover signals in thecase of interference.

    Code type:Voice service: convolutional code (1/2 and 1/3) . The constraint length is9, and 8 tail bits are added.Data service: Turbo code (1/3)

    Interleavingl Interleaving is used to damage symbol correlation and reduce the impact

    caused by fast fading and interference of the channel.

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    HUAWEI TECHNOLOGIES CO., LTD. Page 10Huawei Confidential

    Procedure of SpreadingProcedure of Spreading

    Bit

    OVSFCode

    ScrambleCode

    Chip

    1

    -11

    -11

    -1

    1

    1

    -1

    -1

    Data

    OVSFCode

    Signal=Data

    *code

    OVSFCode

    Data

    Spreading

    Despreading

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    HUAWEI TECHNOLOGIES CO., LTD. Page 11Huawei Confidential

    OVSF Code&Scramble Code

    n Scramble Code (Gold Sequence)

    l Length:38400 Chip

    l Uplink: total 224l Downlink: total 218-1 =262143, only use 0~8191

    SF = 1 SF = 2 SF = 4

    C ch,1,0 = (1)

    C ch,2,0 = (1,1)

    C ch,2,1 = (1,-1)

    C ch,4,0 =(1,1,1,1)

    C ch,4,1 = (1,1,-1,-1)

    C ch,4,2 = (1,-1,1,-1)

    C ch,4,3 = (1,-1,-1,1)

    n OVSF (Orthogonal Variable Spreading Factor) Code

    1

    -1

    1

    -1

    1

    -1

    Code1

    Code2

    Code2_D1

    Multi-path will destroythe orthogonality of

    OVSF!!!

    Multi-path will destroythe orthogonality of

    OVSF!!!

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    HUAWEI TECHNOLOGIES CO., LTD. Page 12Huawei Confidential

    l Users who need to send information: UE1, UE2 and UE3

    [ UE1 uses c1 for spreading: UE1 c1[ UE2 uses c2 for spreading: UE2 c2[ UE3 uses c3 for spreading: UE3 c3[ c1, c2 and c3 are mutually orthogonal.

    l Information sent: UE1 c1+ UE2 c2+ UE3 c3

    Spreading Principle

    l UE1 uses c1 for de-spreading.

    [ (UE1 c1 + UE2 c2 + UE3 c3) c1

    =UE1 (c1 c1) + UE2 (c2 c1) + UE3 (c3 c1)

    =UE1 1 + UE2 0 + UE3 0

    =UE1

    l In the same way, UE2 uses c2 for de-spreading and UE3 uses c3 for de-

    spreading to obtain their own signals.

    De-spreading Principle

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    HUAWEI TECHNOLOGIES CO., LTD. Page 13Huawei Confidential

    Frequency spreading overcomes interference

    Spreading code

    Spreading code

    Signalcombination

    Spectrum Change in WCDMA

    Narrowband signal

    f

    P(f)

    Broadband signal

    P(f)

    f

    Noise + broadband signal

    P (f)

    f

    Separation ofsignals and noise

    P (f)

    f

    Noise+

    other user signal

    P (f)

    f

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    HUAWEI TECHNOLOGIES CO., LTD. Page 14Huawei Confidential

    Advantages of WCDMA over GSMAdvantages of WCDMA over GSM

    q Larger system capacity

    q Higher spectrum efficiency

    q Higher interference tolerance and security performance

    q Higher throughput with multiple services.

    q Adapted to mobility speed of up to 500km/h

    q Reduce the effects of fading through Rake reception

    - Fast fading caused by multi path

    - Slow fading caused by shadowing

    q Supports soft handover and softer handover

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    HUAWEI TECHNOLOGIES CO., LTD. Page 15Huawei Confidential

    Contents

    q Overview of WCDMA

    n Handover Introduction

    n Power Control Introduction

    n UMTS Channels and Function

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    Purpose of handover

    Guarantee continuous conversation, it is a necessary

    requirement in any mobile communication system. Proper

    handover algorithm is propitious to reduce system call dropand increase network capacity.

    90% of radio call drop occurs in the process of handover.

    WCDMA handover types

    1. Soft Handover2. Softer Handover

    3. Hard Handover

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    HUAWEI TECHNOLOGIES CO., LTD. Page 17Huawei Confidential

    Soft Handover (Connection before Disconnection)

    RNCNodeB1NodeB2

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    HUAWEI TECHNOLOGIES CO., LTD. Page 18Huawei Confidential

    Softer Handover (A Special Case of Soft Handover)

    RNCNode B

    Cell A Cell B

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    HUAWEI TECHNOLOGIES CO., LTD. Page 19Huawei Confidential

    Hard Handover- (Disconnection before Connection)

    RNCNodeB1 NodeB2

    Hard Handover- (Disconnection before Connection)

    NodeB1 RNC NodeB2

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    HUAWEI TECHNOLOGIES CO., LTD. Page 20Huawei Confidential

    Rake ReceptionRake Reception

    SHO Gain against slow fading= Slow fading margin without SHOSlow fading margin with SHO

    SHO Gain against fast fading= FastFadingMargin(without SHO)-FastFadingMargin(with SHO)

    Receive set

    Correlator 1

    Correlator 2

    Correlator 3

    Searcher correlator Calculate the time

    delay and signal

    strength

    Combiner The combinedsignal

    tt

    s(t) s(t)

    Reduce theeffects of fading

    through Rakereception

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    HUAWEI TECHNOLOGIES CO., LTD. Page 21Huawei Confidential

    Comparison of Soft and Hard Handover

    Call drop ratio isrelatively higher

    Occupies more resources.Problems occur when the power of soft

    handover cells is unbalanced.

    Disadvantage

    None

    Maximum-ratio combining or selective

    combining which can reduce the impactof fading and transmission power of theUE.

    Handover gain

    Intra-frequencyInter-frequency

    or

    Inter-RAT

    Intra-frequencyFrequencies in the cells

    before and afterhandover

    YesNoInterruption during

    handover

    OneSeveralNumber of radio links inthe activate set

    Hard HandoverSoft Handover (Softer Handover)Item

    In a word, some resources are wasted to obtain optimal system performance in soft

    handover.

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    HUAWEI TECHNOLOGIES CO., LTD. Page 22Huawei Confidential

    Contents

    q Overview of WCDMA

    q Handover Introduction

    q Power Control Introduction

    q UMTS Channels and Function

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    HUAWEI TECHNOLOGIES CO., LTD. Page 23Huawei Confidential

    Purposes of Power Control

    Solve the near-far effect

    Ensure the uplink/downlink quality by adjusting thetransmit power

    Overcoming slow fading and fast fading

    Decrease interference, and improve system quality andcapacity

    In short, the purpose of power control in the WCDMA system isensuring users communication quality with minimum transmit

    power

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    HUAWEI TECHNOLOGIES CO., LTD. Page 24Huawei Confidential

    Near/Far Problem

    A B

    P()

    P()

    P()

    P()

    Power

    received

    from A.

    Power

    receivedfrom B.

    P()

    Output power

    of A

    Output power

    of BTotal receive

    Arecoversuccessful

    Brecoverfailed

    De-spread

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    HUAWEI TECHNOLOGIES CO., LTD. Page 25Huawei Confidential

    After Power Control

    P()

    P()

    P()

    P()

    P()

    A decreases

    its power

    A B

    Output power

    of A

    Output power

    of B

    Arecoversuccessful

    Brecoversuccessful

    De-spread

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    HUAWEI TECHNOLOGIES CO., LTD. Page 26Huawei Confidential

    After Power Control

    P()

    1 2 3 4 5

    P()

    1

    P()

    2

    P()

    3

    P()

    4

    P()

    5Total receiveDe-spread

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    HUAWEI TECHNOLOGIES CO., LTD. Page 27Huawei Confidential

    Interference limit

    De-spread

    P()

    P()

    P()

    P()

    P()

    P()

    P()

    P()

    P()

    P()

    P()

    1 2 3 4 5

    1 2 3 4

    1 2 3 4 5

    Total receive

    Total receive

    De-spread

    O C

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    HUAWEI TECHNOLOGIES CO., LTD. Page 28Huawei Confidential

    Reverse Open Loop Power Control

    The transmission power required by the UE is determined by the

    following factors:

    Distance from the Node B

    Load of the cell

    Circumstance of the code channels

    The transmission power of the UE is relative to its received power.

    Node BUE

    Reverse Open LoopPower Control

    Node B

    Node B

    Transmitting

    Power

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    HUAWEI TECHNOLOGIES CO., LTD. Page 29Huawei Confidential

    Close Loop Power Control

    Node B UE

    Sent TPC

    SIR measurementand comparing

    Inner loop

    SIR target setting

    BLER measurement

    Outer loop

    RNC

    Comparing

    BLER target setting

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    HUAWEI TECHNOLOGIES CO., LTD. Page 30Huawei Confidential

    Contents

    q Overview of WCDMA

    q Handover Introduction

    q Power Control Introduction

    q UMTS Channels and Function

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    HUAWEI TECHNOLOGIES CO., LTD. Page 31Huawei Confidential

    Control channel

    Traffic channel

    Dedicated traffic channel (DTCH)

    Common traffic channel (CTCH)

    Broadcast control channel (BCCH)

    Paging control channel (PCCH)

    Dedicate control channel (DCCH)

    Common control channel (CCCH)

    Logical Channel

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    HUAWEI TECHNOLOGIES CO., LTD. Page 32Huawei Confidential

    Dedicated Channel (DCH)

    -DCH is an uplink or downlink channel

    Broadcast channel (BCH)Forward access channel (FACH)

    Paging channel (PCH)

    Random access channel (RACH)

    High-speed downlink shared channel

    (HS-DSCH)

    Common transportchannel

    Dedicated transportchannel

    Transport Channel

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    HUAWEI TECHNOLOGIES CO., LTD. Page 33Huawei Confidential

    Physical Channel

    A physical channel is defined by a specific carrier frequency,

    code (scrambling code, spreading code) and relative phase.

    In UMTS system, the different code (scrambling code or

    spreading code) can distinguish the channels.

    Most channels consist of radio frames and time slots, and each

    radio frame consists of 15 time slots.

    Two types of physical channel:UL and DL

    Physical Channel

    Frequency, Code, Phase

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    HUAWEI TECHNOLOGIES CO., LTD. Page 34Huawei Confidential

    Function of physical channel

    Node BUE

    P-CCPCH-Primary Common Control Physical Channel

    SCH- Synchronisation Channel (Including P-SCH and S-SCH Channel)

    P-CCPCH-Primary Common Control Physical Channel

    SCH- Synchronisation Channel (Including P-SCH and S-SCH Channel)

    P-CPICH-Primary Common Pilot Channel

    S-CPICH-Secondary Common Pilot Channel

    P-CPICH-Primary Common Pilot ChannelS-CPICH-Secondary Common Pilot Channel

    Cell broadcast channels

    DPDCH-Dedicated Physical Data ChannelDPDCH-Dedicated Physical Data Channel

    DPCCH-Dedicated Physical Control ChannelDPCCH-Dedicated Physical Control Channel

    Dedicated channels

    Paging channels

    PICH-Paging Indicator ChannelPICH-Paging Indicator Channel

    S-CCPCH-Secondary Common Control Physical ChannelS-CCPCH-Secondary Common Control Physical Channel

    PRACH-Physical Random Access ChannelPRACH-Physical Random Access Channel

    AICH-Acquisition Indicator ChannelAICH-Acquisition Indicator Channel

    Random access channels

    HS-DPCCH-High Speed Dedicated Physical Control ChannelHS-DPCCH-High Speed Dedicated Physical Control Channel

    HS-SCCH-High Speed Share Control ChannelHS-SCCH-High Speed Share Control Channel

    HS-PDSCH-High Speed Physical Downlink Share ChannelHS-PDSCH-High Speed Physical Downlink Share Channel

    High speed downlink share channels

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    Thank youwww.huawei.com

    http://www.huawei.com/http://www.huawei.com/