Download - 1 WCDMA Radio Interface Physical Layer ISSUE2.00

8/6/2019 1 WCDMA Radio Interface Physical Layer ISSUE2.00

1/52

WCDMA Radio Interface PhysicalLayer

Confidential Information of Huawei. No Spreading Without Permission

N-0

www.huawei.com

Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA Radio InterfacePhysical Layer


2/52



N-1

Page1Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

Foreword

The physical layer offers data transport services to higher layers.

The physical layer is expected to perform the following functions in

order to provide the data transport service, for example: spreading,

modulation and demodulation, despreading, Inner-loop power

control and etc.


3/52



N-2


Objectives

Upon completion of this course, you will be able to:

Outline radio interface protocol Architecture

Describe structure and functions of different physical channels

Describe UMTS physical layer procedures


4/52



N-3


Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure


5/52



N-4


UTRAN Network Structure

RNS

RNC

RNS

RNC

Core Network

NodeB NodeB NodeB NodeB

Iu-CS Iu-PS

Iur

Iub IubIub Iub

CN

UTRAN

UEUu

CS PS

Iu-CSIu-PS

CSPS

UTRAN: UMTS Terrestrial Radio Access Network.

The UTRAN consists of a set of Radio Network Subsystems connected to the Core Network

through the Iu interface.

A RNS consists of a Radio Network Controller and one or more NodeBs. A NodeB is

connected to the RNC through the Iub interface.

Inside the UTRAN, the RNCs of the RNS can be interconnected together through the Iur.

Iu(s) and Iur are logical interfaces. Iur can be conveyed over direct physical connection

between RNCs or virtual networks using any suitable transport network.


6/52



N-5


Uu Interface Protocol Structure

L3

control

control

control

control

C-plane signaling U-plane information

PHY

L2/MAC

L1

RLC

DCNtGC

L2/RLC

MAC

RLCRLC

RLC

Duplication avoidance

UuS boundary

L2/BMC

control

PDCPPDCP L2/PDCP

DCNtGC

RRC

RLCRLC

RLCRLC

BMC

radio bearer

logical channel

transport channel

The layer 1 supports all functions required for the transmission of bit streams on the

physical medium. It is also in charge of measurements function consisting in indicating to

higher layers, for example, Frame Error Rate (FER), Signal to Interference Ratio (SIR),interference power, transmit power, It is basically composed of a layer 1 management

entity, a transport channel entity, and a physical channel entity.

The layer 2 protocol is responsible for providing functions such as mapping, ciphering,

retransmission and segmentation. It is made of four sub-layers: MAC (Medium Access

Control), RLC (Radio Link Control), PDCP (Packet Data Convergence Protocol) and BMC

(Broadcast/Multicast Control).

The layer 3 is split into 2 parts: the access stratum and the non access stratum. The access

stratum part is made of RRC (Radio Resource Control) entity and duplication avoidance

entity. duplication avoidance terminates in the CN but is part of the Access Stratum. Thehigher layer signalling such as Mobility Management (MM) and Call Control (CC) is

assumed to belong to the non-access stratum, and therefore not in the scope of 3GPP TSG

RAN. In the C-plane, the interface between 'Duplication avoidance' and higher L3 sub-

layers (CC, MM) is defined by the General Control (GC), Notification (Nt) and Dedicated

Control (DC) SAPs.

Not shown on the figure are connections between RRC and all the other protocol layers

(RLC, MAC, PDCP, BMC and L1), which provide local inter-layer control services.

The protocol layers are located in the UE and the peer entities are in the NodeB or the RNC.


7/52



N-6

Many functions are managed by the RRC layer. Here is the list of the most important:

Establishment, re-establishment, maintenance and release of an RRC

connection between the UE and UTRAN: it includes an optional cell re-selection,

an admission control, and a layer 2 signaling link establishment. When a RNC is in

charge of a specific connection towards a UE, it acts as the Serving RNC.

Establishment, reconfiguration and release of Radio Bearers: a number of

Radio Bearers can be established for a UE at the same time. These bearers are

configured depending on the requested QoS. The RNC is also in charge of ensuring

that the requested QoS can be met.

Assignment, reconfiguration and release of radio resources for the RRC

connection: it handles the assignment of radio resources (e.g. codes, shared

channels). RRC communicates with the UE to indicate new resources allocation

when handovers are managed.

Paging/Notification: it broadcasts paging information from network to UEs.

Broadcasting of information provided by the non-access stratum (Core Network)

or access Stratum. This corresponds to system information regularly repeated.

UE measurement reporting and control of the reporting: RRC indicates what

to measure, when and how to report.

Outer loop power control: controls setting of the target values.

Control of ciphering: provides procedures for setting of ciphering.

The RRC layer is defined in the 25.331 specification from 3GPP.


8/52



N-7

The RLCs main function is the transfer of data from either the user or the control plane

over the Radio interface. Two different transfer modes are used: transparent and non-

transparent. In non-transparent mode, 2 sub-modes are used: acknowledged or

unacknowledged.

RLC provides services to upper layers:

data transfer (transparent, acknowledged and unacknowledged modes).

QoS setting: the retransmission protocol (for AM only) shall be configurable by

layer 3 to provide different QoS.

notification of unrecoverable errors: RLC notifies the upper layers of errors that

cannot be resolved by RLC.

The RLC functions are:

mapping between higher layer PDUs and logical channels.

ciphering: prevents unauthorized acquisition of data; performed in RLC layer for

non-transparent RLC mode.

segmentation/reassembly: this function performs segmentation/reassembly of

variable-length higher layer PDUs into/from smaller RLC Payload Units. The RLC size

is adjustable to the actual set of transport formats (decided when service is

established). Concatenation and padding may also be used.

error correction: done by retransmission (acknowledged data transfer mode only).

flow control: allows the RLC receiver to control the rate at which the peer RLC

transmitting entity may send information.


9/52



N-8

MAC services include:

Data transfer: service providing unacknowledged transfer of MAC SDUs between

peer MAC entities.

Reallocation of radio resources and MAC parameters: reconfiguration of MACfunctions such as change of identity of UE. Requested by the RRC layer.

Reporting of measurements: local measurements such as traffic volume and

quality indication are reported to the RRC layer.

The functions accomplished by the MAC sub-layer are listed above. Heres a quick

explanation for some of them:

Priority handling between the data flows of one UE: since UMTS is multimedia,

a user may activate several services at the same time, having possibly different

profiles (priority, QoS parameters...). Priority handling consists in setting the right

transport format for a high bit rate service and for a low bit rate service.

Priority handling between UEs: use for efficient spectrum resources utilization for

bursty transfers on common and shared channels.

Ciphering: to prevent unauthorized acquisition of data. Performed in the MAC

layer for transparent RLC mode.

Access Service Class (ACS) selection for RACH transmission: the RACH

resources are divided between different ACSs in order to provide different priorities

on a random access procedure.


10/52



N-9

PDCP

UMTS supports several network layer protocols providing protocol transparency for

the users of the service.

Using these protocols (and new ones) shall be possible without any changes toUTRAN protocols. In order to perform this requirement, the PDCP layer has been

introduced. Then, functions related to transfer of packets from higher layers shall be

carried out in a transparent way by the UTRAN network entities.

PDCP shall also be responsible for implementing different kinds of optimization

methods. The currently known methods are standardized IETF (Internet Engineering

Task Force) header compression algorithms.

Algorithm types and their parameters are negotiated by RRC and indicated to PDCP.

Header compression and decompression are specific for each network layer protocol

type.

In order to know which compression method is used, an identifier (PID: Packet

Identifier) is inserted. Compression algorithms exist for TCP/IP, RTP/UDP/IP,

Another function of PDCP is to provide numbering of PDUs. This is done if lossless

SRNS relocation is required.

To accomplish this function, each PDCP-SDUs (UL and DL) is buffered and numbered.

Numbering is done after header compression. SDUs are kept until information of

successful transmission of PDCP-PDU has been received from RLC. PDCP sequence

number ranges from 0 to 65,535.


11/52



N-10

BMC (broadcast/multicast control protocol)

The main function of BMC protocol are:

Storage of cell broadcast message. the BMC in RNC stores the cell broadcast

message received over the CBC-RNC interface for scheduled transmission.

Traffic volume monitoring and radio resource request for CBS. On the UTRAN

side, the BMC calculates the required transmission rate for the cell broadcast service

based on the messages received over the CBC-RNC interface, and requests

appropriate .CTCH/FACH resources from from RRC

Scheduling of BMC message. The BMC receives scheduling information together

with each cell broadcast message over the CBC-RNC interface. Based on this

scheduling information, on the UTRAN side the BMC generates schedule message

and schedules BMC message sequences accordingly. On the UE side ,the BMC

evaluates the schedule messages and indicates scheduling parameters to RRC, whichare used by RRC to configure the lower layers for CBS discontinuous reception.

Transmission of BMC message to UE. The function transmits the BMC messages

according to the schedule

Delivery of cell broadcast messages to the upper layer. This UE function

delivers the received non-corrupted cell broadcast messages to the upper layer


12/52



N-11

The layer 1 (physical layer) is used to transmit information under the form of electrical

signals corresponding to bits, between the network and the mobile user. This information

can be voice, circuit or packet data, and network signaling.

The UMTS layer 1 offers data transport services to higher layers. The access to these

services is through the use of transport channels via the MAC sub-layer.

These services are provided by radio links which are established by signaling procedures.

These links are managed by the layer 1 management entity. One radio link is made of

one or several transport channels, and one physical channel.

The UMTS layer 1 is divided into two sub-layers: the transport and the physical sub-layers.

All the processing (channel coding, interleaving, etc.) is done by the transport sub-layer in

order to provide different services and their associated QoS. The physical sub-layer is

responsible for the modulation, which corresponds to the association of bits (coming from

the transport sub-layer) to electrical signals that can be carried over the air interface. The

spreading operation is also done by the physical sub-layer.

These two parts of layer 1 are controlled by the layer 1 management (L1M) entity. It is

made of several units located in each equipment, which exchange information through the

use of control channels.


13/52



N-12


RAB, RB and RL

RAB

RB

RLNodeB

RNC CNUE

UTRAN

RAB: The service that the access stratum provides to the non-access stratum for transfer of

user data between User Equipment and CN.

RB: The service provided by the layer 2 for transfer of user data between User Equipmentand Serving RNC.

RL: A "radio link" is a logical association between single User Equipment and a single

UTRAN access point. Its physical realization comprises one or more radio bearer

transmissions.


14/52



N-13


Contents





15/52



N-14


Contents


2.1 Physical Channel Structure and Functions

2.2 Channel Mapping


16/52



N-15


WCDMA Radio Interface Channel Definition

Logical Channel = information container

Defined by is transferred

Transport Channel = characteristics of transmission

Described by and with data is

transmitted over the radio interface

Physical Channel = specification of the information global

content

providing the real transmission resource, maybe a frequency , a

specific set of codes and phase

In terms of protocol layer, the WCDMA radio interface has three types of channels: physical

channel, transport channel and logical channel.

Logical channel: Carrying user services directly. According to the types of the carried

services, it is divided into two types: control channel and service channel.

Transport channel: It is the interface between radio interface layer 2 and layer 1, and it is

the service provided for MAC layer by the physical layer. According to whether the

information transported is dedicated information for a user or common information for all

users, it is divided into dedicated channel and common channel.

Physical channel: It is the ultimate embodiment of all kinds of information when they are

transmitted on radio interface. Each channel which uses dedicated carrier frequency, code

(spreading code and scramble) and carrier phase (I or Q) can be regarded as a physical

channel.


17/52



N-16


Logical Channel

Control channel

Traffic channelDedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)

As in GSM, UMTS uses the concept of logical channels.

A logical channel is characterized by the type of information that is transferred.

As in GSM, logical channels can be divided into two groups: control channels for controlplane information and traffic channel for user plane information.

The traffic channels are:

Dedicated Traffic Channel (DTCH): a point-to-point bi-directional channel, that

transmits dedicated user information between a UE and the network. That

information can be speech, circuit switched data or packet switched data. The

payload bits on this channel come from a higher layer application (the AMR codec

for example). Control bits can be added by the RLC (protocol information) in case of

a non transparent transfer. The MAC sub-layer will also add a header to the RLC

PDU.

Common Traffic Channel (CTCH): a point-to-multipoint downlink channel for

transfer of dedicated user information for all or a group of specified UEs. Thischannel is used to broadcast BMC messages. These messages can either be cell

broadcast data from higher layers or schedule messages for support of

Discontinuous Reception (DRX) of cell broadcast data at the UE. Cell broadcast

messages are services offered by the operator, like indication of weather, traffic,

location or rate information.


18/52



N-17


Logical Channel

Control channel

Traffic channelDedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)

The control channels are:

Broadcast Control Channel (BCCH): a downlink channel that broadcasts all system

information types (except type 14 that is only used in TDD). For example, system informationtype 3 gives the cell identity. UEs decode system information on the BCH except when in

Cell_DCH mode. In that case, they can decode system information type 10 on the FACH and

other important signaling is sent on a DCCH.

Paging Control Channel (PCCH): a downlink channel that transfers paging information. It

is used to reach a UE (or several UEs) in idle mode or in connected mode (Cell_PCH or

URA_PCH state). The paging type 1 message is sent on the PCCH. When a UE receives a

page on the PCCH in connected mode, it shall enter Cell_FACH state and make a cell update

procedure.

Dedicated Control Channel (DCCH): a point-to-point bi-directional channel that

transmits dedicated control information between a UE and the network. This channel is used

for dedicated signaling after a RRC connection has been done. For example, it is used for

inter-frequency handover procedure, for dedicated paging, for the active set update

procedure and for the control and report of measurements.

Common Control Channel (CCCH): a bi-directional channel for transmitting control

information between network and UEs. It is used to send messages related to RRC

connection, cell update and URA update. This channel is a bit like the DCCH, but will be

used when the UE has not yet been identified by the network (or by the new cell). For

example, it is used to send the RRC connection request message, which is the first message

sent by the UE to get into connected mode. The network will respond on the same channel,

and will send him its temporary identities (cell and UTRAN identities). After these initial

messages, the DCCH will be used.


19/52



N-18


Transport Channel

Dedicated Channel (DCH)

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

In order to carry logical channels, several transport channels are defined. They are:

Broadcast Channel (BCH): a downlink channel used for broadcast of system

information into the entire cell. Paging Channel (PCH): a downlink channel used for broadcast of control

information into the entire cell, such as paging.

Random Access Channel (RACH): a contention based uplink channel used for

initial access or for transmission of relatively small amounts of data (non real-time

dedicated control or traffic data).

Forward Access Channel (FACH): a common downlink channel used for

dedicated signaling (answer to a RACH typically), or for transmission of relatively

small amounts of data.

Dedicated Channel (DCH): a channel dedicated to one UE used in uplink or

downlink.


20/52



N-19


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

Now we will begin to discuss the physical channel. Physical channel is the most important

and complex channel, and a physical channel is defined by a specific carrier frequency,

code and relative phase. In CDMA system, the different code (scrambling code orspreading code) can distinguish the channel. Most channels consist of radio frames and

time slots, and each radio frame consists of 15 time slots. There are two types of physical

channel: UL and DL.


21/52



N-20


Downlink Physical Channel

Downlink Dedicated Physical Channel (DL DPCH)

Downlink Common Physical Channel

Primary Common Control Physical Channel (P-CCPCH)

Secondary Common Control Physical Channel (S-CCPCH)

Synchronization Channel (SCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Common Pilot Channel (CPICH)

High-Speed Physical Downlink Shared Channel (HS-PDSCH)

High-Speed Shared Control Channel (HS-SCCH)

The different physical channels are:

Synchronization Channel (SCH): used for cell search procedure. There is theprimary and the secondary SCHs.

Common Control Physical Channel (CCPCH): used to carry common controlinformation such as the scrambling code used in DL (there is a primary CCPCH andadditional secondary CCPCH).

Common Pilot Channels (P-CPICH and S-CPICH): used for coherent detection ofcommon channels. They indicate the phase reference.

Dedicated Physical Data Channel (DPDCH): used to carry dedicated data comingfrom layer 2 and above (coming from DCH).

Dedicated Physical Control Channel (DPCCH): used to carry dedicated controlinformation generated in layer 1 (such as pilot, TPC and TFCI bits).

Page Indicator Channel (PICH): carries indication to inform the UE that paginginformation is available on the S-CCPCH.

Acquisition Indicator Channel (AICH): it is used to inform a UE that the networkhas received its access request.

High Speed Physical Downlink Shared Channel (HS-PDSCH): it is used to carrysubscribers BE service data (mapping on HSDPA) coming from layer 2.

High Speed Shared Control Channel (HS-SCCH): it is used to carry controlmessage to HS-PDSCH such as modulation scheme, UE ID etc.


22/52



N-21


Uplink Physical Channel

Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel (Uplink DPDCH)

Uplink Dedicated Physical Control Channel (Uplink DPCCH)

High-Speed Dedicated Physical Channel (HS-DPCCH)

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

The different physical channels are:

Dedicated Physical Data Channel (DPDCH): used to carry dedicated data coming

from layer 2 and above (coming from DCH). Dedicated Physical Control Channel (DPCCH): used to carry dedicated control

information generated in layer 1 (such as pilot, TPC and TFCI bits).

Physical Random Access Channel (PRACH): used to carry random access

information when a UE wants to access the network.

High Speed Dedicated Physical Control Channel (HS-DPCCH): it is used to

carry feedback message to HS-PDSCH such CQI,ACK/NACK.


23/52



N-22


Function of Physical Channel

NodeB UE

P-CCPCH-Primary Common Control Physical ChannelP-CCPCH-Primary Common Control Physical Channel

P-CPICH--Primary Common Pilot Channel

SCH--Synchronisation Channel

P-CPICH--Primary Common Pilot Channel

SCH--Synchronisation Channel

Cell Search 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

SCCPCH--Secondary Common Control Physical ChannelSCCPCH--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


24/52



N-23


Synchronization Channels (P-SCH & S-SCH)

Used for cell search

Two sub channels: P-SCH and S-SCH

SCH is transmitted at the first 256 chips

of every time slot

Primary synchronization code istransmitted repeatedly in each time slot

Secondary synchronization code specifies

the scrambling code groups of the cell

PrimarySCH

SecondarySCH

Slot #0 Slot #1 Slot #14

ac si,0

pac pac pac

ac si,1 acs

i,14

256 chips

2560 chips

One 10 ms SCH radio frame

When a UE is turned on, the first thing it does is to scan the UMTS spectrum and find a

UMTS cell. After that, it has to find the primary scrambling code used by that cell in order

to be able to decode the BCCH (for system information). This is done with the help of the

Synchronization Channel.

Each cell of a NodeB has its own SCH timing, so that there is no overlapping.

The SCH is a pure downlink physical channel broadcasted over the entire cell. It is

transmitted unscrambled during the first 256 chips of each time slot, in time multiplex with

the P-CCPCH. It is the only channel that is not spread over the entire radio frame. The

SCH provides the primary scrambling code group (one out of 64 groups), as well as the

radio frame and time slot synchronization.

The SCH consists of two sub-channels, the primary and secondary SCH. These sub-

channels are sent in parallel using code division during the first 256 chips of each time slot.

P-SCH always transmits primary synchronization code. S-SCH transmits secondary

synchronization codes.

The primary synchronization code is repeated at the beginning of each time slot. The same

code is used by all the cells and enables the mobiles to detect the existence of the UMTS

cell and to synchronize itself on the time slot boundaries. This is normally done with a

single matched filter or any similar device. The slot timing of the cell is obtained by

detecting peaks in the matched filter output.

This is the first step of the cell search procedure. The second step is done using the

secondary synchronization channel.


25/52



N-24


Secondary Synchronization Channel (S-SCH)

slot numberScramblingCode Group #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

..acp

Slot # ?

P-SCH acp

Slot #?

16 6S-SCH

acp

Slot #?

11Group 2Slot 7, 8, 9

256 chips

The S-SCH also consists of a code, the Secondary Synchronization Code (SSC) that

indicates which of the 64 scrambling code groups the cells downlink scrambling code

belongs to. 16 different SSCs are defined. Each SSC is a 256 chip long sequence.

There is one specific SSC transmitted in each time slot, giving us a sequence of 15 SSCs.

There is a total of 64 different sequences of 15 SSCs, corresponding to the 64 primary

scrambling code groups. These 64 sequences are constructed so that one sequence is

different from any other one, and different from any rotated version of any sequence. The

UE correlates the received signal with the 16 SSCs and identifies the maximum correlation

value.

The S-SCH provides the information required to find the frame boundaries and the

downlink scrambling code group (one out of 64 groups). The scrambling code (one out of

8) can be determined afterwards by decoding the P-CPICH. The mobile will then be able todecode the BCH.


26/52



N-25


Primary Common Pilot Channel (PCPICH)

Primary PCPICH

Carrying pre-defined sequence

Fixed channel code: Cch, 256, 0, Fixed rate 30Kbps

Scrambled by the primary scrambling code

Broadcast over the entire cell

A phase reference for SCH, Primary CCPCH, AICH, PICH and downlink

DPCH, Only one PCPICH per cell

Pre-defined symbol sequence

Slot #0 Slot #1 Slot # i Slot #14

Tslot = 2560 chips , 20 bits

1 radio frame: Tr = 10 ms

The Common Pilot Channel (CPICH) is a pure physical control channel broadcasted overthe entire cell. It is not linked to any transport channel. It consists of a sequence of knownbits that are transmitted in parallel with the primary and secondary CCPCH.

The PCPICH is used by the mobile to determine which of the 8 possible primary scramblingcodes is used by the cell, and to provide the phase reference for common channels.

Finding the primary scrambling code is done during the cell search procedure through asymbol-by-symbol correlation with all the codes within the code group. After the primaryscrambling code has been identified, the UE can decode system information on the P-CCPCH.

The P-CPICH is the phase reference for the SCH, P-CCPCH, AICH and PICH. It isbroadcasted over the entire cell. The channelization code used to spread the P-CPICH isalways Cch,256,0 (all ones). Thus, the P-CPICH is a fixed rate channel. Also, it is alwaysscrambled with the primary scrambling code of the cell.


27/52



N-26


Primary Common Control Physical Channel

(PCCPCH)

Carrying BCH transport channel

Fixed rate, fixed OVSF code (30kbpsCch, 256, 1)

The PCCPCH is not transmitted during the first 256 chips of each time

slot

PCCPCH Data

18 bits

Slot #0

1 radio frame: Tf

= 10 ms

Slot #1 Slot #i

256 chips

Slot #14

Tslot

= 2560 chips,20 bits

SCH

The Primary Common Control Physical Channel (P-CCPCH) is a fixed rate (SF=256)

downlink physical channel used to carry the BCH transport channel. It is broadcasted

continuously over the entire cell like the P-CPICH.

The figure above shows the frame structure of the P-CCPCH. The frame structure is special

because it does not contain any layer 1 control bits. The P-CCPCH only has one fix

predefined transport format combination, and the only bits transmitted are data bits from

the BCH transport channel. It is important to note that the P-CCPCH is not transmitted

during the first 256 chips of the slot. In fact, another physical channel (SCH) is transmitted

during that period of time. Thus, the SCH and the P-CCPCH are time multiplexed on every

time slot.

Channelization code Cch,256,1 is always used to spread the P-CCPCH.


28/52



N-27


Paging Indicator Channel (PICH)

Carrying Paging Indicators (PI)

Fixed rate (30kbps), SF = 256

N paging indicators {PI0, , PIN-1} in each PICH frame, N=18, 36, 72,

or 144

One radio frame (10 ms)

b1b0

288 bits for paging indication 12 bits (undefined)

b287 b288 b299

The Page Indicator Channel (PICH) is a fixed rate (30kbps, SF=256) physical channel

used by the NodeB to inform a UE (or a group of UEs) that a paging information will soon

be transmitted on the PCH. Thus, the mobile only decodes the S-CCPCH when it is

informed to do so by the PICH. This enables to do other processing and to save the

mobiles battery.

The PICH carries Paging Indicators (PI), which are user specific and calculated by higher

layers. It is always associated with the S-CCPCH to which the PCH is mapped.

The frame structure of the PICH is illustrated above. It is 10 ms long, and always contains

300 bits (SF=256). 288 of these bits are used to carry paging indicators, while the

remaining 12 are not formally part of the PICH and shall not be transmitted. That part of

the frame (last 12 bits) is reserved for possible future use.

In order not to waste radio resources, several PIs are multiplexed in time on the PICH.

Depending on the configuration of the cell, 18, 36, 72 or 144 paging indicators can bemultiplexed on one PICH radio frame. Thus, the number of bits reserved for each PI

depends of the number of PIs per radio frame. For example, if there is 72 PIs in one radio

frame, there will be 4 (288/72) consecutive bits for each PI. These bits are all identical. If

the PI in a certain frame is 1, it is an indication that the UE associated with that PI should

read the corresponding frame of the S-CCPCH.


29/52



N-28


Secondary Common Control Physical Channel

(SCCPCH)

Carrying FACH and PCH, SF = 256 - 4

Pilot: used for demodulation

TFCI: Transport Format Control Indication, used for describe data format

Data

N bits

Slot #0 Slot #1 Slot #i Slot #14

1 radio frame: T f= 10 ms

T slot = 2560 chips,

Data

PilotN bitsPilotN bits

TFCI

TFCI

20*2 k bits (k=0..6)

The Secondary Common Control Physical Channel (S-CCPCH) is used to carry the

FACH and PCH transport channels. Unlike the P-CCPCH, it is not broadcasted

continuously. It is only transmitted when there is a PCH or FACH information to transmit.

At the mobile side, the mobile only decodes the S-CCPCH when it expects a useful message

on the PCH or FACH.

A UE will expect a message on the PCH after indication from the PICH (page indicator

channel), and it will expect a message on the FACH after it has transmitted something on

the RACH.

The FACH and the PCH can be mapped on the same or on separate S-CCPCHs. If they are

mapped on the same S-CCPCH, TFCI bits have to be sent to support multiple transport

formats

The figure above shows the frame structure of the S-CCPCH. There are 18 different slot

formats determining the exact number of data, pilot and TFCI bits. The data bitscorrespond to the PCH and/or FACH bits coming from the transport sub-layer. Pilot bit are

typically used when beamforming techniques are used.

The SF ranges from 4 to 256. The channelization code is assigned by the RRC layer as is

the scrambling code, and they are fixed during the communication. They are sent on the

BCCH so that every UE can decode the channel.

As said before, FACH can be used to carry user data. The difference with the dedicated

channel is that it cannot use fast power control, nor soft handover. The advantage is that it

is a fast access channel.


30/52



N-29


Physical Random Access Channel (PRACH)

Carrying uplink signaling and data, consist of two parts:

One or several preambles: 16 kinds of available preambles

10 or 20ms message part

Message partPreamble

4096 chips10 ms (one radio frame)

Preamble Preamble

Message partPreamble

4096 chips 20 ms (two radio frames)

Preamble Preamble

The Physical Random Access Channel (PRACH) is used by the UE to access the network

and to carry small data packets. It carries the RACH transport channel. The PRACH is an

open loop power control channel, with contention resolution mechanisms (ALOHAapproach) to enable a random access from several users.

The PRACH is composed of two different parts: the preamble part and the message part

that carries the RACH message. The preamble is an identifier which consists of 256

repetitions of a 16 chip long signature (total of 4096 chips). There are 16 possible

signatures, basically, the UE randomly selects one of the 16 possible preambles and

transmits it at increasing power until it gets a response from the network (on the AICH).

That preamble is scrambled before being sent. That is a sign that the power level is high

enough and that the UE is authorized to transmit, which it will do after acknowledgment

from the network. If the UE doesnt get a response from the network, it has to select a

new signature to transmit.

The message part is 10 or 20 ms long (split into 15 or 30 time slots) and is made of the

RACH data and the layer 1 control information.


31/52



N-30


PRACH Message Structure

Pilot

N bits

Slot # 0 Slot # 1 Slot # i Slot # 14

Message part radio frame T = 10 ms

Tslot = 2560 chips, 10*2

Pilot

TFCI

N bitsTFCI

Data

Ndata

bitsData

Control

k bits (k=0..3)

The data and control bits of the message part are processed in parallel. The SF of the data

part can be 32, 64, 128 or 256 while the SF of the control part is always 256. The control

part consists of 8 pilot bits for channel estimation and 2 TFCI bits to indicate the transportformat of the RACH (transport channel), for a total of 10 bits per slot.

The OVSF codes to use (one for RACH data and one for control) depend on the signature

that was used for the preamble (for signatures s=0 to s=15: OVSFcontrol= Cch,256,m, where

m=16s + 15; OVSFdata= Cch,SF,m, where m=SF*s/16.


32/52



N-31


PRACH Access Timeslot Structure

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

5120 chips

radio frame: 10 ms radio frame: 10 ms

Access slot #0 Random Access Transmission

Access slot #1

Access slot #7

Access slot #14

Random Access Transmission



Access slot #8

The PRACH transmission is based on the access frame structure. The access frame isaccess of 15 access slots and lasts 20 ms (2 radio frames).

To avoid too many collisions and to limit interference, a UE must wait at least 3 or 4 access

slots between two consecutive preambles.

The PRACH resources (access slots and preamble signatures) can be divided betweendifferent Access Service Classes (ASC) in order to provide different priorities of RACH usage.The ASC number ranges from 0 (highest priority) to 7 (lowest priority).


33/52



N-32


Acquisition Indicator Channel (AICH)

Carrying the Acquisition Indicators (AI), SF = 256

There are 16 kinds of Signature to generate AI

AS #14 AS #0 AS #1 AS #i AS #14 AS #0

a1 a2a0 a31 a32a30 a33 a38 a39

AI part Unused part

20 ms

The Acquisition Indicator Channel (AICH) is a common downlink channel used to control

the uplink random accesses. It carries the Acquisition Indicators (AI), each corresponding

to a signature on the PRACH (uplink). When the NodeB receives the random access from a

mobile, it sends back the signature of the mobile to grant its access. If the NodeB receives

multiple signatures, it can sent all these signatures back by adding the together. At

reception, the UE can apply its signature to check if the NodeB sent an acknowledgement

(taking advantage of the orthogonality of the signatures).

The AICH consists of a burst of data transmitted regularly every access slot frame. One

access slot frame is formed of 15 access slots, and lasts 2 radio frames (20 ms). Each

access slot consists of two parts, an acquisition indicator part of 32 real-valued symbols

and a long part during which nothing is transmitted to avoid overlapping due to

propagation delays.

s (with values 0, +1 and -1, corresponding to the answer from the network to a specific

user) and the 32 chip long sequence is given by a predefined table. There are 16sequences , each corresponding to one PRACH signatures. A maximum of 16 AIs

can be sent in each access slot. The user can multiply the received multi-level signal by the

signature it used to know if its access was granted.

The SF used is always 256 and the OVSF code used by the cell is indicated in system

information type 5.


34/52



N-33



(DPDCH&DPCCH)

Uplink DPDCH and DPCCH are I/Q code division multiplexed

(CDM) within each radio frame

DPDCH carries data generated at Layer 2 and higher layer, the

OVSF code is Cch,SF,SF/4, where SF is from 256 to 4

DPCCH carries control information generated at Layer 1, the

OVSF code is Cch,256,0

There are two kinds of uplink dedicated physical channels, the Dedicated Physical Data

Channel (DPDCH) and the Dedicated Physical Control Channel (DPCCH). The DPDCH

is used to carry the DCH transport channel. The DPCCH is used to carry the physical sub-layer control bits.

Each DPCCH time slot consists of Pilot, TFCIFBITPC

Pilot is used to help demodulation

TFCI: transport format control indicator

FBI:used for the FBTD. (feedback TX diversity)

TPC: used to transport power control command.


35/52



N-34



(DPDCH&DPCCH)

Frame Structure of Uplink DPDCH/DPCCH

PilotNpilot bits

TPCNTPC bits

DataNdata bits


Tslot = 2560 chips, 10*2k bits (k=0..6)

1 radio frame: Tf = 10 ms

DPDCH

DPCCHFBI

NFBI bitsTFCI

NTFCI bits

On the figure above, we can see the DPDCH and DPCCH time slot constitution. The

parameter k determines the number of symbols per slot. It is related to the spreading

factor (SF) of the DPDCH by this simple equation: SF=256/2k

. The DPDCH SF ranges from 4to 256. The SF for the uplink DPCCH is always 256, which gives us 10 bits per slot. The

exact number of pilot, TFCI, TPC and FBI bits is configured by higher layers. This

configuration is chosen from 12 possible slot formats. It is important to note that symbols

are transmitted during all slots for the DPDCH


36/52



N-35


Downlink Dedicated Physical Channel

(DPDCH+DPCCH)

Downlink DPDCH and DPCCH is time division multiplexing

(TDM).

DPDCH carries data generated at Layer 2 and higher layer

DPCCH carries control information generated at Layer 1

SF of downlink DPCH is from 512 to 4

The uplink DPDCH and DPCCH are I/Q code multiplexed. But the downlink DPDCH and

DPCCH is time multiplexed. This is main difference.

Basically, there are two types of downlink DPCH. They are distinguished by the use or non

use of the TFCI field. TFCI bits are not used for fixed rate services or when the TFC doesnt

change.


37/52



N-36


Downlink Dedicated Physical Channel

(DPDCH+DPCCH)

Frame Structure of Downlink DPCH (DPDCH+DPCCH)

One radio frame, Tf= 10 ms


Tslot = 2560 chips, 20*2k bits (k=-1..6)

Data2

Ndata2 bits

DPDCH

TFCI

NTFCI bits

Pilot

Npilot bits

Data1

Ndata1 bits

DPDCH DPCCH DPCCH

TPC

NTPC bits

We have known that the uplink DPDCH and DPCCH are I/Q code multiplexed. But the

downlink DPDCH and DPCCH is time multiplexed. This is main difference. The parameter k

in the figure above determines the total number of bits per time slot. It is related to the SF,which ranges from 4 to 512. The chips of one slot is also 2560.

Downlink physical channels are used to carry user specific information like speech, data or

signaling, as well as layer 1 control bits. Like it was mentioned before, the payload from

the DPDCH and the control bits from the DPCCH are time multiplexed on every time slot.

The figure above shows how these two channels are multiplexed. There is only one

DPCCH in downlink for one user.


38/52



N-37


High-Speed Physical Downlink Shared Channel

(HS-PDSCH)

Bearing service data and layer 2 overhead bits mapped from thetransport channel

SF=16, can be configured several channels to increase data service

Slot #0 Slot#1 Slot #2

Tslot = 2560 chips, M*10*2k bits (k=4)

DataNdata1 bits

1 subframe: Tf= 2 ms

HS-PDSCH is a downlink physical channel that carries user data and layer 2 overhead bits

mapped from the transport channel: HS-DSCH.

The user data and layer 2 overhead bits from HS-DSCH is mapped onto one or several HS-

PDSCH and transferred in 2ms subframe using one or several channelization code with

fixed SF=16.


39/52



N-38


High-Speed Shared Control Channel (HS-SCCH)

Carries physical layer signalling to a single UE ,such as modulation scheme (1bit) ,channelization code set (7 bit), transport block size (6bit),HARQ process

number (3bit), redundancy version (3bit), new data indicator (1bit), UE

identity (16bit)

HS-SCCH is a fixed rate (60 kbps, SF=128) downlink physical channel used to

carry downlink signalling related to HS-DSCH transmission

Slot #0 Slot#1 Slot #2

Tslot = 2560 chips, 40 bits

DataNdata1 bits

1 subframe: Tf= 2 ms

HS-SCCH uses a SF=128 and has q time structure based on a sub-frame of length 2 ms, i.e.

the same length as the HS-DSCH TTI. The timing of HS-SCCH starts two slot prior to the

start of the HS-PDSCH subframe.

The following information is carried on the HS-SCCH (7 items)

Modulation scheme(1bit) QPSK or 16QAM

Channelization code set (7bits)

Transport block size ( 6bits)

HARQ process number (3bits)

Redundancy version (3bits)

New Data Indicator (1bit)

UE identity (16 bits)

In each 2 ms interval corresponding to one HS-DSCH TTI , one HS-SCCH carries physical-

layer signalling to a single UE. As there should be a possibility for HS-DSCH transmission to

multiple users in parallel (code multiplex), multiplex HS-SCCH may be needed in a cell. The

specification allows for up to four HS-SCCHs as seen from a UE point of view .i.e. UE must

be able to decode four HS-SCCH.


40/52



N-39


High-Speed Dedicated Physical Control Channel(HS-DPCCH )

Carrying information to acknowledge downlink transport blocks andfeedback information to the system for scheduling and link

adaptation of transport block

CQI and ACK/NACK

Physical Channel, Uplink, SF=256

Subframe #0 Subframe #i Subframe #n

One HS-DPCCH subframe ( 2ms )

ACK/NACK

1 radio frame: Tf = 10 ms

CQI

Tslot = 2560 chips 2 Tslot = 5120 chips

The uplink HS-DPCCH consists of:

Acknowledgements for HARQ

Channel Quality Indicator (CQI)

As the HS-DPCCH uses SF=256, there are a total of 30 channel bits per 2 ms sub frame (3

time slot). The HS-DPCCH information is divided in such a way that the HARQ

acknowledgement is transmitted in the first slot of the subframe while the channel quality

indication is transmitted in the rest slot.


41/52



N-40


Contents


2.1 Physical Channel Structure and Functions

2.2 Channel Mapping


42/52



N-41


Mapping Between Channels

Logical channels Transport channels Physical channels

BCCH BCH P-CCPCH

FACH S-CCPCH

PCCH PCH S-CCPCH

CCCH RACH PRACH

FACH S-CCPCH

CTCH FACH S-CCPCH

DCCH, DTCH DCH DPDCH

HS-DSCH HS-PDSCH

RACH, FACH PRACH, S-CCPCH

This page indicates how the mapping can be done between logical, transport and physical

channels. Not all physical channels are represented because not all physical channels

correspond to a transport channel.

The mapping between logical channels and transport channels is done by the MAC sub-

layer.

Different connections can be made between logical and transport channels:

BCCH is connected to BCH and may also be connected to FACH;

DTCH can be connected to either RACH and FACH, to RACH and DSCH, to DCH and

DSCH, to a DCH or a CPCH;

CTCH is connected to FACH;

DCCH can be connected to either RACH and FACH, to RACH and DSCH, to DCH and

DSCH, to a DCH or a CPCH;

PCCH is connected to PCH;

CCCH is connected to RACH and FACH.

These connections depend on the type of information on the logical channels.


43/52



N-42


Contents





44/52



N-43


Synchronization Procedure - Cell Search

Frame synchronization &Code Group Identification

Scrambling CodeIdentification

UE uses SSC to find framesynchronization and identify the codegroup of the cell found in the first step

UE determines the primary scrambling

code through correlation over the PCPICHwith all codes within the identified group,and then detects the P-CCPCH and readsBCH information

SlotSynchronization

UE uses PSC to acquire slotsynchronization to a cell

The purpose of the Cell Search Procedure is to give the UE the possibility of finding a celland of determining the downlink scrambling code and frame synchronization of that cell.This is typically performed in 3 steps:

PSCH (Slot synchronization): The UE uses the SCHs primary synchronization code toacquire slot synchronization to a cell. The primary synchronization code is used bythe UE to detect the existence of a cell and to synchronize the mobile on the TSboundaries. This is typically done with a single filter (or any similar device) matchedto the primary synchronization code which is common to all cells. The slottiming of the cell can be obtained by detecting peaks in the matched filter output.

SSCH (Frame synchronization and code-group identification): The secondarysynchronization codes provide the information required to find the frame boundariesand the group number. Each group number corresponds to a unique set of 8primary scrambling codes. The frame boundary and the group number are providedindirectly by selecting a suite of 15 secondary codes. 16 secondary codes have been

defined C1, C2, .C16. 64 possible suites have been defined, each suite correspondsto one of the 64 groups. Each suite of secondary codes is composed of 15secondary codes (chosen in the set of 16), each of which will be transmitted in onetime slot. When the received codes matches one of the possible suites, the UE hasboth determined the frame boundary and the group number.

PCPICH (Scrambling-code identification): The UE determines the exact primaryscrambling code used by the found cell. The primary scrambling code is typicallyidentified through symbol-by-symbol correlation over the PCPICH with all the codeswithin the code group identified in the second step. After the primary scramblingcode has been identified, the Primary CCPCH can be detected and the system- andcell specific BCH information can be read.


45/52



N-44


Random Access

Procedure

START

Choose a RACH sub channel fromavailable ones

Get available signatures

Set Preamble Retrans Max

Set Preamble_Initial_Power

Send a preamble

Check the corresponding AI

Increase message part power byp-m based on preamble power

Set physical status to be RACHmessage transmitted

Set physical status to be Nackon AICH received

Choose a access slot again

Counter> 0 & Preamble power< maximum allowed power

Choose a signature andincrease preamble transmit power

Set physical status to be Nackon AICH received

Get negative AI

No AI

Report the physical status to MAC

END

Get positive AI

The counter of preamble retransmitSubtract 1, Commanded preamble power

increased by Power Ramp Step

N

Y

Send the corresponding message part

Physical random access procedure

1. Derive the available uplink access slots, in the next full access slot set, for the set of available RACH

sub-channels within the given ASC. Randomly select one access slot among the ones previously

determined. If there is no access slot available in the selected set, randomly select one uplink access slotcorresponding to the set of available RACH sub-channels within the given ASC from the next access slot

set. The random function shall be such that each of the allowed selections is chosen with equal

probability

2. Randomly select a signature from the set of available signatures within the given ASC.

3. Set the Preamble Retransmission Counter to Preamble_ Retrans_ Max

4. Set the parameter Commanded Preamble Power to Preamble_Initial_Power

5. Transmit a preamble using the selected uplink access slot, signature, and preamble transmission power.

6. If no positive or negative acquisition indicator (AI +1 nor 1) corresponding to the selected signature

is detected in the downlink access slot corresponding to the selected uplink access slot:

A: Select the next available access slot in the set of available RACH sub-channels within the given

ASC; B: select a signature;

C: Increase the Commanded Preamble Power;

D: Decrease the Preamble Retransmission Counter by one. If the Preamble RetransmissionCounter > 0 then repeat from step 6. Otherwise exit the physical random access procedure.

7. If a negative acquisition indicator corresponding to the selected signature is detected in the downlink

access slot corresponding to the selected uplink access slot, exit the physical random access procedure

Signature

8. If a positive acquisition indicator corresponding to the selected signature is detected , Transmit the

random access message three or four uplink access slots after the uplink access slot of the last

transmitted preamble

9. exit the physical random access procedure


46/52



N-45


Transmit Diversity Mode

Application of Tx diversity modes on downlink physical channel

appliedAICH

appliedHS-SCCH

appliedappliedHS-PDSCH

appliedPICH

appliedappliedappliedDPCH

appliedS-CCPCH

appliedSCH

appliedP-CCPCH

Mode 2Mode 1STTDTSTD

Closed loop modeOpen loop modePhysical channel type

Transmitter-antenna diversity can be used to generate multi-path diversity in places where

it would not otherwise exist. Multi-path diversity is a useful phenomenon, especially if it

can be controlled. It can protect the UE against fading and shadowing. TX diversity isdesigned for downlink usage. Transmitter diversity needs two antennas, which would be

an expensive solution for the UEs.

The UTRA specifications divide the transmitter diversity modes into two categories: (1)

open-loop mode and (2) closed-loop mode. In the open-loop mode no feedback

information from the UE to the NodeB is available. Thus the UTRAN has to determine by

itself the appropriate parameters for the TX diversity. In the closed-loop mode the UE sends

feedback information up to the NodeB in order to optimize the transmissions from the

diversity antennas.

Thus it is quite natural that the open-loop mode is used for the common channels, as theytypically do not provide an uplink return channel for the feedback information. Even if

there was a feedback channel, the NodeB cannot really optimize its common channel

transmissions according to measurements made by one particular UE. Common channels

are common for everyone; what is good for one UE may be bad for another. The closed-

loop mode is used for dedicated physical channels, as they have an existing uplink channel

for feedback information. Note that shared channels can also employ closed loop power

control, as they are allocated for only one user at a time, and they also have a return

channel in the uplink. There are two specified methods to achieve the transmission diversity

in the open-loop mode and two methods in closed-loop mode


47/52



N-46


Transmit Diversity - STTD

Space time block coding based transmit antenna diversity (STTD)

4 consecutive bits b0, b1, b2, b3 using STTD coding

b0 b1 b2 b3 Antenna 1

Antenna 2Channel bits

STTD encoded channel bitsfor antenna 1 and antenna 2.

b0 b1 b2 b3

-b2 b3 b0 -b1

The TX diversity methods in the open-loop mode are

space time-block coding-based transmit-antenna diversity (STTD)

time-switched transmit diversity (TSTD).

In STTD the data to be transmitted is divided between two transmission antennas at the

base station site and transmitted simultaneously. The channel-coded data is processed in

blocks of four bits. The bits are time reversed and complex conjugated, as shown in above

slide. The STTD method, in fact, provides two brands of diversity. The physical separation

of the antennas provides the space diversity, and the time difference derived from the bit-

reversing process provides the time diversity.

These features together make the decoding process in the receiver more reliable. In

addition to data signals, pilot signals are also transmitted via both antennas. The normal

pilot is sent via the first antenna and the diversity pilot via the second antenna.

The two pilot sequences are orthogonal, which enables the receiving UE to extract the

phase information for both antennas.

The STTD encoding is optional in the UTRAN, but its support is mandatory for the UEs

receiver.


48/52



N-47


Transmit Diversity - TSTD

Time switching transmit diversity (TSTD) is used only on SCH

channel

Antenna 1

Antenna 2

i,0

i,1

acsi,14

Slot #0 Slot #1 Slot #14

i,2

acp

Slot #2

(TxOFF)

(TxOFF)

(TxOFF)

(TxOFF)

(Tx

OFF)(TxOFF)

(Tx

OFF)

acp acp

acsacs

acp

acs(TxOFF)

Time-switched transmit diversity (TSTD) can be applied to the SCH. Just like STTD, the

support of TSTD is optional in the UTRAN, but mandatory in the UE. The principle of TSTD

is to transmit the synchronization channels via the two base station antennas in turn. Ineven-numbered time slots the SCHs are transmitted via antenna 1, and in odd-numbered

slots via antenna 2. This is depicted in above Figure. Note that SCH channels only use the

first 256 chips of each time slot (i.e., one-tenth of each slot).


49/52



N-48


Closed Loop Mode

Used in DPCH and HS-PDSCH

The closed-loop-mode transmit diversity can only be applied to the downlink channel if

there is an associated uplink channel. Thus this mode can only be used with dedicated

channels. The chief operating principle of the closed loop mode is that the UE can controlthe transmit diversity in the base station by sending adjustment commands in FBI bits on

the uplink DPCCH. The UE uses the base stations common pilot channels to estimate the

channels separately. Based on this estimation, it generates the adjustment information and

sends it to the UTRAN to maximize the UEs received power.

There are actually two modes in the closed-loop method. In mode 1 only the phase can be

adjusted; in mode 2 the amplitude is adjustable as well as the phase. Each uplink time slot

has one FBI bit for closed-loop-diversity control. In mode 1 each bit forms a separate

adjustment command, but in mode 2 four bits are needed to compose a command.

This functions can be configured by LMT command ADD CELLSETUP.


50/52



N-49


References

TS 25.104 UTRA (BS) FDD Radio Transmission and Reception

TS 25.201 Physical layer-general description

TS 25.211 Physical channels and mapping of transport channels onto physical

channels (FDD)

TS 25.212 Multiplexing and channel coding (FDD)

TS 25.213 Spreading and modulation (FDD)

TS 25.214 Physical layer procedures (FDD)

TS 25.308 UTRA High Speed Downlink Packet Access (HSDPA)

TR 25.877 High Speed Downlink Packet Access (HSDPA) - Iub/Iur Protocol Aspects

TR 25.858 Physical layer aspects of UTRA High Speed Downlink Packet Access


51/52



N-50


This course mainly introduces the basic concept, key

technology and procedures of WCDMA physical layer.

These knowledge is very important for understanding Uu

interface and further study.

Summary


52/52


N-51

Thank youwww.huawei.com