1. UMTS & HSDPA Fundamentals Version 4.0

Proprietary and Confidential

UMTS and HSDPA UMTS and HSDPA FundamentalsFundamentals

Version 4.0

West Region - UMTS RF Engineering

Proprietary and Confidential Slide 2

UMTS FundamentalsUMTS Fundamentals• Module OverviewModule Overview

This module provides training material relating to the key UMTS concepts as This module provides training material relating to the key UMTS concepts as is required for the practical optimization of a UMTS network.is required for the practical optimization of a UMTS network.

– System Overview

– WCDMA Air Interface

– Radio Resource Management

– HSDPA


WCDMA System OverviewWCDMA System Overview


WCDMA Network TopologyWCDMA Network Topology

Iu-CS Sig

Iu-CS Sig

IubIub

PSTN

IP Domain

(Wap, Internet, Streaming)GGSN

3GSGSN

WCDMA Air Interface

Uu

Iu-PSIu-PS

User Equipment (UE)& USIM

Node Bs RNC

2G Net

MSC

MGWIu-CS UserIu-CS User


UMTS ServicesUMTS Services


R99 Services - QoSR99 Services - QoS

• Conversational– Voice– Video

• Streaming– Mobile TV

• Interactive– Web Browsing– Email

• Background– File Transfer


WCDMA Air Interface WCDMA Air Interface OverviewOverview


WCDMA Air InterfaceWCDMA Air Interface

• Multiple Access Technology – CDMA

• Modulation – QPSK / 16QAM

• Carrier Spacing – 5MHz on 200khz raster

• Frame Length – 10ms / 2ms

• Slots per frame – 15

• Multiple Rates – Multi-code / Variable Spreading Factor

• Chip rate – 3.84Mcps

• Max Data Rate – 14.4Mbps

• Synchronous – No

• Handover – Soft


Spectrum Allocation - AWSSpectrum Allocation - AWS


CDMA - Code Division Multiple AccessCDMA - Code Division Multiple Access

freq

uen

cy

time

code


ModulationModulation

QPSK

2 bits / symbol

10 00

0111

Q

I

Q

1011 1001

10001010

0001 0011

00100000

0100 0110

01110101

1110 1100

11011111

I

16QAM

4 bits / symbol


Spreading and DespreadingSpreading and Despreading

Identical codes

Tx Bit Stream

P

f

Code Chip Stream

Spreading

P

f

Channel

Air Interface Chip Stream

P

f

Code Chip Stream

Despreading

P

f

Rx Bit Stream

P

f


Spreading and Processing GainSpreading and Processing Gain


WCDMA Spreading CodesWCDMA Spreading Codes

SF 4

SF 8

SF 16

SF 2

• WCDMA used Orthogonal Variable Spreading Factor (OVSF) Codes to spread user data in both the uplink and the downlink

• The maximum spreading factor used in UMTS is 512

• DL Speech uses SF=128

• DL 384k used SF=8


WCDMA Scrambling CodesWCDMA Scrambling Codes• After spreading the bit stream is scrambled

• In the uplink – one SC per UE

• In the downlink – (typically) one SC per sector

Spreading Code

Spreading

User Bit Stream

Scrambling

Scrambling Code

TX Bit Stream


WCDMA Code SummaryWCDMA Code SummarySynchronisation Codes Channelisation Codes Scrambling Codes, UL Scrambling Codes, DL

Type

Gold Codes, Primary Synchronization Codes (PSC)

and Secondary Synchronization Codes (SSC)

Orthogonal Variable Spreading Factor (OVSF) codes,

sometimes called Walsh codes

Complex-Valued Gold Code Segments (long) or Complex-

Valued S(2) Codes (short)

Complex-Valued Gold Code Segments

Length 256 chips 4-512 chips 38400 chips /256 chips 38400 chips

Duration 66.67 µs 1.04 µs - 133.34 µs 10 ms / 66.67 µs 10 ms

Number of codes

1 primary code / 16 secondary codes

= spreading factor, 4 ... 256 UL, 4 ... 512 DL

16,777,216512 primary / 15 secondary for

each primary code

Spreading No, does not change bandwidth Yes, increases bandwidth No, does not change bandwidth No, does not change bandwidth

UsageTo enable terminals to locate and synchronise to the cells'

main control channels

UL: to separate physical data and control data from same

terminal. DL: to separate connection to different terminals

in a same cell

Separation of terminal Separation of sectors


Rake ReceiverRake Receiver• Rake receiver is able to track and actively combine multipath components

of the same signal, this process is called maximal ratio combining.

• UE uses a rake receiver with 3 – 6 fingers

• Node B uses rake receiver with 6 – 8 fingers


Downlink Channel MappingDownlink Channel Mapping

BCCHBroadcast Control Ch.

PCCHPaging Control Ch.

CCCHCommon Control Ch.

DCCHDedicated Control Ch.

DTCHDedicated Traffic Ch. N

BCHBroadcast Ch.

PCHPaging Ch.

FACHForward Access Ch.

DCHDedicated Ch.

P-CCPCH(*)Primary Common Control Physical Ch.

S-CCPCHSecondary Common Control

Physical Ch.

DPDCH (one or more per UE) Dedicated Physical Data Ch.

DPCCH (one per UE)Dedicated Physical Control Ch.

Pilot, TPC, TFCI bits

SSCi

Logical Channels(Layers 2+)

Transport Channels(Layer 2)

Physical Channels(Layer 1)

DownlinkRF Out

DPCH (Dedicated Physical Channel)One per UE

HS-DSCHHigh Speed DL Shared Ch.

CPICHCommon Pilot Channel

Null Data

Data Encoding

Data Encoding

Data Encoding

Data Encoding

Data Encoding

HS- PDSCH (one or more per UE) High Speed Physical Downlink shared Channel

S/P

S/P

S/P

I+jQI/Q

Modulator

Q

I

Cch

Cch 256,1

Cch 256,0

GS

PSC

GP

Sync Codes(*)

* Note regarding P-CCPCH and SCH

Sync Codes are transmitted only in bits 0-255 of each timeslot;P-CCPCH transmits only during the remaining bits of each timeslot

Filter

Filter

Gain

Gain

Gain

SCH (Sync Channel)

DTCHDedicated Traffic Ch. 1

DCHDedicated Ch.

Data Encoding M

UX

MUX

CCTrCH

DCHDedicated Ch.

Data Encoding

Sdl,n

Sdl,n

Sdl,n

S/P

Cch GainSdl,n

S/P

C16 GainSdl,n

AICH (Acquisition Indicator Channel)

PICH (Paging Indicator Channel )

Access Indication data

Paging Indication bits S/P

S/P

Cch

CchGain

Gain

Sdl,n

Sdl,n

HS-SCCH (<=4 per UE)High Speed Shared Control Channel .

S/P

C128 GainSdl,n

TFRI, UE Identity, HARQ

SS

SS

E-AGCH (<=4 per UE, serving cell)E-DCH Absolute Grant Channel

S/P

C256 GainSdl,n

C128 GainSdl,n

E-HICH (E-DCH Hybrid ARQ Indication Channel)

E-RGCH (non-serving cell)(E-DCH Relative Grant Channel)

ACK/NACK

Relative grant

Activation flagPower ratio

Data Encoding

Data Encoding

EUL

HSDPA


Uplink Channel MappingUplink Channel MappingLogical Channels(Layers 2+)

Transport Channels(Layer 2)

Physical Channels(Layer 1)

UplinkRF Out

UEScrambling

Code

I+jQI/Q

Mod.

Q

IFilter

Filter

IDPDCH #1Dedicated Physical Data Ch.

Q

DPCCHDedicated Physical Control Ch.

Pilot, TPC, TFCI bits

Ch256,0 Gd

j

DCCHDedicated Control Ch.

DTCHDedicated Traffic Ch. N

DCHDedicated Ch.

Data Encoding

DTCHDedicated Traffic Ch. 1

DCHDedicated Ch.

Data Encoding M

UX

CCTrCH

DCHDedicated Ch.

Data Encoding

HS-DPCCHHigh Speed Dedicated Physical Control Ch.

Chd,1 Gd

CCCHCommon Control Ch.

RACHRandom Access Ch.

PRACHPhysical Random Access Ch.

Data Coding

j

RACH Control Part

Chd Gd

Chc Gc

Ch256 Gd

QE-DPDCH #2

Ch 4,1

GdE-DCH

E-DPCCH

I

Ch 256,1Gd

E-DPDCH #1

Ch 4,1 Gd

j

RSNE-TFCI

Happy bit

Data Encoding

MAC-esMAC-e

Data Encoding

ACK, CQI

HSDPA

EUL


WCDMA WCDMA Air Interface Key Air Interface Key ConceptsConcepts


CPICH – Pilot / BeaconCPICH – Pilot / Beacon

• The Common Pilot Indication 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 cell

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

CPICH


3G Coverage Measurements3G Coverage Measurements• The majority of 3G coverage measurements are based upon measurements

of the CPICH

• In 3G, coverage is defined by Ec and EcIo

• Golden Rule: If the UE can’t see the CPICH the UE can’t see the cell.

• Three key related measurements for 3G optimisation are– RSCP - The Received Signal Level of a particular CPICH (dBm)– Io - The Total Received Power (dBm)– Ec/Io - The CPICH Quality (The ratio of the above two values)


CPICH MeasurementsCPICH Measurements

• Io is the total received power (also referred to as RSSI), this includes all wanted and unwanted signals as well as noise in dBm.

• RSCP is the received power of a single scrambling code (also referred to as Ec) in dBm

• EcIo is the ratio of RSCP to Io in dB

Io

RSCP

EcIodB

m

Ec1Ec2EcIo1EcIo2


CPICH Measurements - CPICH Measurements - ExampleExample

• Ec2 = -85 dBm

• EcIo1 = -10dB

• Io = -70dBm

• What is the RSCP for SC1?

• What is the EcIo for SC2?

Io

RSCP

EcIodB

m

SC1SC2


Radio Resource ManagementRadio Resource Management


Radio Resource ManagementRadio Resource Management• Overview of Radio Resource Management (RRM)Overview of Radio Resource Management (RRM)

– Aim of RRM is to efficiently manage the Radio Resources of the WCDMA air interface

– Different vendors have implemented different RRM strategies and algorithms– Generally RRM functions can be group as follows

• Admission Control• Load Control• Packet Scheduler• Resource Management

• Power Control• Handover Control

Cell Based

Connection Based


Power ControlPower Control


Power ControlPower Control• Power is a limited resourcePower is a limited resource

– In any CDMA network, the power of the BTS and UE must be tightly controlled to avoid interference to other BTSs/UEs


Power ControlPower Control• Types of Power ControlTypes of Power Control

– Open Loop Power Control• Used to set the initial transmit power of the BTS/UE

– Closed Loop Power Control• Used to control power of uplink/downlink DCHs• Inner Loop (Or Fast Power Control) used to control TX Power (UL/DL)• Outer Loop (Or Slow Power Control) used to control SIR Targets (UL/DL)


Open Loop Power ControlOpen Loop Power Control• Open Loop Power Control Open Loop Power Control

– Open Loop Power Control – Used to set the initial transmit power of the UE– UPLINK: Uses a measure of DL path loss to provide estimate uplink path loss– UPLINK: CPICH measurement by the UE along with the reported BTS Noise

Floor are used to determine the initial TX power of the UE

Preamble_Initial_power = CPICH_Tx_power – CPICH_RSCP + UL_interference + UL_required_CI

CPICH_Tx_powerUL_Interference

UL_required_CI

CPICH_RSCP


Closed Loop Power ControlClosed Loop Power Control• Closed Loop Power ControlClosed Loop Power Control

– Enables the BTS/UE to rapidly adjust their DCH TX powers to track the changing channel conditions (path loss & interference) in order to maintain the required SIR at the receiving UE/BTS

– Uses feedback (power control commands) in the opposite link to adjust Tx power accordingly

Example of Real Fast Fading - Dense UrbanManchester

-105

-100

-95

-90

-85

-80

-75

-70

-65

-60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Time (secs)


Closed Loop Power ControlClosed Loop Power Control• Inner Loop Power Control (Fast Power Control)Inner Loop Power Control (Fast Power Control)

– Transmit Power Control (TPC) commands (up/down) issued to UE (Uplink) and BTS (Downlink) to maintain Target SIR every time slot (1500 Hz)

– Power control step size typically 1dB (Algorithm 1)– Below 30km/h 1.5KHz and 1dB is fast enough to track changes– Above 30km/h other schemes such as (Algorithm 2) maybe more suitable

User Equipment (UE)& USIM

Node Bs

UuUu

Inner Loop PC

Inner Loop PC

Required SIRDL

Required SIRUL


Closed Loop Power ControlClosed Loop Power Control• Outer Loop Power ControlOuter Loop Power Control

– RNC compares uplink BLER with BLER target and sets SIRUL accordingly

– UE compares downlink BLER with BLER target and set SIRDL accordingly

– Frequency 10 to 100 Hz– Step size 0.1 to 1dB

IubIub

User Equipment (UE)& USIM Node Bs RNC

UuUu

Outer Loop PCOuter

Loop PC


WCDMA HandoversWCDMA Handovers


Handovers in WCDMAHandovers in WCDMA• Soft Handover

– Intra-system Handover

• Hard Handover– Inter-frequency Handover– Inter-system Handover


Neighbour Lists & Active SetNeighbour Lists & Active Set• The Neighbor ListThe Neighbor List

– In WCDMA like GSM each cell has to declare at list of valid neighbors• Intra-system neighbors (32 Max)• Inter-frequency neighbors (32 Max)• Inter-system neighbors (32 Max)

• The Active SetThe Active Set– The Active Set is defined as the list of cells the UE is connected to during

dedicated mode– Active set size = 1: UE Not in Soft Handover– Active set size > 1: UE in Soft Handover– Typically Active set size limited to 3


• Softer handover occurs between sectors of the same site

• Soft handover occurs between sectors of different sites

• For both softer and soft handover UE Ec/Io measurements are used to determine whether a cell should be added or removed from the active set

Soft & Softer HandoverSoft & Softer Handover


Soft HandoverSoft Handover• Updating the Active SetUpdating the Active Set

IoIo

EcIo1EcIo1

EcIo3EcIo3

-60dBm-60dBm

-5dBm-5dBm

EcIo2EcIo2 -10dBm-10dBm

-18dBm-18dBm

- Addition Window – event 1a

- Drop Window – event 1b

- Replacement Window – event 1c

- Best Server Replacement – event 1d


Handovers - Inter frequency Handovers - Inter frequency HOHO

• Inter frequency handover occurs between two WCDMA carriers

• This is a hard handover, CM required for UE’s with single receiver

• Used once operator deploys its second carrier, for microcell layer or capacity purposes

f1f2


Inter system HOInter system HO• Inter system handover occurs between 3G and other systems

• CM required for UE’s with a single receiver

• Voice service is a hard handover and is transparent to the user

• Data service is treated as a reselection not a hard handover and data interruption results.

• As with all handovers, accurate adjacencies are required, this is not only important to ensure seamless customer experience when moving in and out of 3G coverage but also to meet the mandated requirements for E911.

3G 2G


CM – Compressed ModeCM – Compressed Mode• Typical Dual Mode 3G/2G UEs utilize a single TRX

• To detect potential IF/IS handover candidates the UE has to share the receiver.

• To create the time required to measure another frequency/frequencies without disrupting the current service compressed mode is used.

• During compressed mode the UE’s spreading factor is halved and the instantaneous transmit power is increased in the compressed frame in order to keep the quality (BER, FER, etc.) unaffected by the resulting reduction in processing gain.

• This creates a “gap” in which the RX can be retuned and IF or IS neighbors scanned.


RRM – Cell BasedRRM – Cell Based


Admission ControlAdmission Control• Admission ControlAdmission Control

– Responsible for determining if the system (Air Interface, Code Tree, Channel Elements, Iub, RNC, Iu etc), can accept the call

• Air Interface (Uplink Load, Downlink Load/Tx Power) ?• Code Tree – Fragmentation ?• NodeB Processing Capacity ?• Iub Capacity ?• RNC Capacity ?

– May give priority to different types of calls• Typically voice/video take precedent

– Considers reports from Load Control Entity to assist decisions


Load ControlLoad Control• Load ControlLoad Control

– Responsible for ensuring cell does not go into overload condition– Constantly monitoring Uplink Rx power and Downlink Tx power– Preventative action taken to avoid overload condition– Load reports sent to Admission Control and Packet Scheduler


Packet SchedulerPacket Scheduler• Packet SchedulePacket Schedule

– Responsible for maximizing throughput of cell/users– Considers reports from Load Control Entity to assist decisions– Should allocate the best bearer for the job

• HSDPA / 384k / 128k / 64k / 32k / FACH etc.

Time

Load

Load Target

CS Load

Free Capacity forPS or HSDPA


Resource ManagerResource Manager• Resource ManagerResource Manager

– Responsible for ensuring efficient use of cells processing capacity• Code use• Channel element use

SF 4

SF 8

SF 16

384 user #1128 user #1

384 user #2


Q & AQ & A


HSDPA FundamentalsHSDPA Fundamentals


What’s New with HSDPAWhat’s New with HSDPA

• HSDPA – High Speed Downlink Packet Access– HSDPA makes use of shared channels, rather than assigning specific resource

for the transfer of user data, users are scheduled on shared channels.

• Fast Link Adaptation– Instead of using power control to compensate for varying radio environment, the

data rate can be adjusted every 2ms.

• Fast HARQ with soft combining– Instead of handling all retransmissions at the RNC, a new HARQ process is

introduced at the Node B to realize rapid retransmission of erroneous data

• Fast Channel Dependent Scheduling– Scheduler is implemented at the Node B as opposed to the RNC to allow for fast

scheduling to accommodate the user environment.


HSDPA Protocol StackHSDPA Protocol Stack


UE CategoriesUE Categories

10

9

7/8

5/6

3/4

1/2

12

11

HSDPACategory

-

-

-

3.6 Mbps

1.8 Mbps

1.2 Mbps

1.8 Mbps

0.9 Mbps

5 Codes

--36302QPSK only

--36301QPSK only

QPSK/16QAM

QPSK/16QAM

QPSK/16QAM

QPSK/16QAM

QPSK/16QAM

QPSK/16QAM

Modulation

14.0 Mbps

10.1 Mbps

-

-

-

-

15 Codes

-279521

-202511

7.2 Mbps144111

-72981

-72982

-72983

10 CodesTransportBlock size

(bits)Inter-TTI (MS)


Downlink HSDPA Code AllocationsDownlink HSDPA Code Allocations

• SF16 codes assigned to HS-PDSCH, 5, 10 or 15 (3GPP)• SF128 assigned to the HS-SCCH (3GPP) (up to 4)• Maximum of 15 codes in Ericsson and Nokia• HS-PDSCH code resources are assigned to one user at a time

HS-PDSCH

SF=1

SF=2

SF=4

SF=8

SF=16

SF=32

SF=64

SF=128

SF=256

CPICH P-CCPCH

S-CCPCH

HS-SCCH

S-CCPCH

Free code that can be allocated to e.g. DPCH, HS-PDSCH (SF16) or HS-SCCH (SF128).

Code that cannot be allocated due to allocations lower in the code-tree / branch.

Code reserved for a common channel.

Legend:


Hybrid ARQ (HARQ)Hybrid ARQ (HARQ)

• ARQ = Automatic Repeat Request – uses error detection to determine if a PDU is received in error

• Hybrid ARQ uses forward error correction as well as error detection resulting in improved performance over ARQ.

• Employed between the UE and the Node B

• UE transmits ACK/NACK to indicate the successful / unsuccessful reception of a PDU.

• HARQ round trip time is longer (approx. 12ms) than a TTI period and as such multiple HARQ processes are used to prevent waiting for ACK/NACK before sending the next PDU

• Retransmissions are combined with original transmissions using soft combining (called chase combining) to improve error correction.


Hybrid ARQ and Soft CombiningHybrid ARQ and Soft Combining

NB. If more than 4 NACK are received for the same packet, the coding rate is changed to higher error correction or the buffer in Node B is flushed and re-filled from the RNC.


Link AdaptationLink Adaptation

• Transport Format Resource Combination (TFRC) changes on the air interface are adapted depending on a Channel Quality Indicator (CQI) sent from the UE.

• The Node B uses this reported CQI as a reference but fine tunes the actual TFRC assignment depending on the last series of ACKs or NACKs, UE capability, actual transmit power, amount of buffered data etc.

• CQI levels change depending on UE type. Attached is the CQI mapping for a CAT 8 UE.

• The TFRC can be modified in each TTI. -516-QAM101441130

-416-QAM101441129

-316-QAM101441128

-216-QAM101441127

-116-QAM101441126

016-QAM101441125

016-QAM81141824

016-QAM7971923

016-QAM5716822

016-QAM5655421

016-QAM5588720

016-QAM5528719

016-QAM5466418

016-QAM5418917

016-QAM5356516

0QPSK5331915

0QPSK4258314

0QPSK4227913

0QPSK3174212

0QPSK3148311

0QPSK3126210

0QPSK29319

0QPSK27928

0QPSK26507

0QPSK14616

0QPSK13775

0QPSK13174

0QPSK12333

0QPSK11732

019200

0QPSK11371

Out of rangeN/A0

XrvNIRReference power adjustment Modulation

Number of HS-PDSCH

Transport Block Size

CQI value

-516-QAM101441130

-416-QAM101441129

-316-QAM101441128

-216-QAM101441127

-116-QAM101441126

016-QAM101441125

016-QAM81141824

016-QAM7971923

016-QAM5716822

016-QAM5655421

016-QAM5588720

016-QAM5528719

016-QAM5466418

016-QAM5418917

016-QAM5356516

0QPSK5331915

0QPSK4258314

0QPSK4227913

0QPSK3174212

0QPSK3148311

0QPSK3126210

0QPSK29319

0QPSK27928

0QPSK26507

0QPSK14616

0QPSK13775

0QPSK13174

0QPSK12333

0QPSK11732

019200

0QPSK11371

Out of rangeN/A0

XrvNIRReference power adjustment Modulation

Number of HS-PDSCH

Transport Block Size

CQI value


Power Control in HSDPAPower Control in HSDPA

• Fast Link Adaptation provides a mechanism to adequately accommodate changes in the radio environment.

• Initially power control of the HS-PDSCH was not used, however vendors have now implemented various degrees of power control to reduce HSDPA impact to other services.

• Ericsson – HS-SCCH has power control– HS-DSCH has power control

• For Nokia– HS-SCCH has power control – HS-DSCH is set at minimum power but can absorb extra power if available to increase

throughput.

• Associated DCH is power controlled using fast power control.


SchedulersSchedulers• The scheduler schedules the information that will be sent from the

Node B to the UE.• The scheduler requires important information from the uplink HS-

DPCCH and other sources

Scheduler

QoS and Subscriber ProfileWho is the subscriber? Platinum, Gold,Silver, Normal.What type of service is the subscriber allowed? High priority, Besteffort

Uplink FeedbackCQI and Ack/Nackinformation

Node B buffer statusHow much data is in bufferHow fast is the data arriving

User HistoryHow long has userbeen waiting

Traffic ModelWhat type of traffic model shouldbe used - according to periodof the day – Peak/Off Peak

Available Radio ResourcesPowerCodes

UE Capability

Users are scheduled according to theirrequirements for transmission by theNode B over the air interface


• Simplest form of scheduler

• First in First out principle

• Advantages:

• Easy to implement

• Minimises waiting time

• Fair

• Disadvantage:

• System Throughput not optimal.

UE 1 Datasent

UE 2 Datasent

UE 1

UE 6

UE 5

UE 4

UE3

UE 2

UE 3 Datasent

UE 4 Datasent

UE 5 Datasent

UE 6 Datasent

UE 1 DataRequest

UE 2 DataRequest

UE 3 dataRequest

UE 4 Data Request

UE 5 DataRequest

UE 6 DataRequest

NodeB PacketScheduler

Round Robin SchedulerRound Robin Scheduler

NodeB Buffers


Proportional Fair SchedulerProportional Fair Scheduler

• Schedules users based on– CQI – Average throughput – Retransmission (time between NACK reception and retransmission)– Delay (time since last scheduled)


HSDPA MobilityHSDPA Mobility

• There is no SHO for the HS-PDSCH channels

• This is due to – Location of the scheduler (Node B level)– Resource requirements on Iub / Channel Elements (CE)

• There are 3 methods for continuing data while HSDPA is in SHO area1. Suspend data till SHO area has expired

2. Radio Bearer reconfiguration to a DCH in SHO area, then re-attempt a HSDPA call setup when SHO area expires

3. SHO of the A-DCH and effectively do a cell reselection for the HS channel to the new best server (depends on vendor support)

• Ericsson Supports SHO of A-DCH in P5, Nokia Supports in RAS 5.1


HSDPA Mobility - SHO for Associated DCHHSDPA Mobility - SHO for Associated DCH


HSDPA assignmentHSDPA assignment

• When HSDPA is enabled on a cell – DSP capacity (channel elements) is permanently assigned as a pool, this resource can not be used by other services.

• Only transmits when data is ready to transmit

• Power, code and transmission resource are temporarily reserved as required

• No Hold times in HSDPA state (FACH hold time is applied but no Iub reservation)

• HSDPA is a more efficient way of transporting bursty PS data than DCH ever could be.


Q & AQ & A

1. UMTS & HSDPA Fundamentals Version 4.0

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