3g rpls ru20 02 the physical layer rel99 v2

7/18/2019 3G RPLS RU20 02 the Physical Layer Rel99 v2

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1 Nokia Siemens Networks 3G RPLS (RN 3155) / RU20 / AA / 01_2010

Course Content

Warming UpThe Physical Layer Rel. 99

The Physical Layer HSDPA, HSUPA & HSPA+

RRC Modes, System Information, Paging & Update Procedures

Cell Selection & Reselection

RRC Connection Establishment

WCDMA Measurements in the UE

Mobility Management & Connection Management

UTRAN Control Protocol Overview (without RRC)


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Module Objectives

At the end of the module you will be able to:

Describe the WCDMA channel structure

Explain transport channel format

List different code types

Name the main differences in UL and DL data transmission organisation

Describe the UE cell synchronisation

Outline the paging organisation and its impact on the UE

Characterise the random access, its power control and code planning

Describe the DPCHs, their power control, time organisation, and L1synchronisation


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The Physical Layer Rel. 99

Channel Mapping

Transport Channel Formats Cell Synchronisation

Common Control Physical Channels

Physical Random Access

Dedicated Physical Channel Downlink

Dedicated Physical Channel Uplink


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

System information, paging, user data, link management

Transport Channelslogical channel information is organised on transport channel

resources before being physically transmitted

Physical Channels(UARFCN, spreading code)

FramesIub interface

Radio Interface Channel Organisation


5/976 Nokia Siemens Networks 3G RPLS (RN 3155) / RU20 / AA / 01_2010

There are two types of logical channels (FDD mode):

1) Control Channels (CCH):

Broadcast Control Channel (BCCH)

System information is made available on this channel. The system information informs the UE about the serving PLMN, the serving cell, neighbourhood lists,

measurement parameters, etc.

This information permanently broadcasted in the DL.

Paging Control Channel (PCCH)

Given the BCCH information the UE can determine, at what times it may be paged.

Paging is required, when the RNC has no dedicated connection to the UE.

PCCH is a DL channel.

Common Control Channel (CCCH) for UL & DL Control information

in use, when no RRC connection exists between the UE and the network

Dedicated Control Channel (DCCH)

UL & DL: Layer 3 Signalling dedicated to a specific radio link.

2) Traffic Channels (TCH):

Dedicated Traffic Channel (DTCH)

UL & DL: dedicated resources for User data transmission between the UE and the network Common Traffic Channel (CTCH)

DL only: User data to be transmitted point-to-multipoint to a group of UEs.

Logical Channels


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Logical Channels are mapped onto Transport Channels. There are two types of Transport Channels (FDD mode):

a) Common Transport Channels:

Broadcast Channel (BCH)

It carries the BCCH information.

Paging Channel (PCH)It is in use to page a UE in the cell, thus it carries the PCCH information. It is also used to notify UEs about cell

system information changes.

Forward Access Channel (FACH)The FACH is a DL channel. Control information, but also small amounts of user data can be transmitted on this

channel.

Random Access Channel (RACH)This UL channel is used by the UE, when small amounts of data have to be transmitted; the UE requires no

Dedicated resources. It is often used to allocated dedicated signalling resources to the UE to establish a connection

or to perform higher layer signalling. It is a contention based channel, i.e. several UE may attempt to access UTRAN

simultaneously.

b) Dedicated Transport Channels:

Dedicated Channel (DCH)

Dedicated resources can be allocated both UL & DL to a UE. Dedicated resources are exclusively in use for thesubscriber.

HS-Downlink Shared Channel (HS-DSCH) & E-DCHTransport Channels for DL HSDPA respectively UL HSUPA data transfer

Note: DSCH (FDD), CPCH removed from R5 specification, 25.301 v5.6.0

Transport Channels (TrCH)


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Physical Channels are characterised by

UARFCN,

Scrambling Code, Channelisation Code (optional),

start and stop time, and

relative phase (in the UL only, with relative phase being 0 or /2)

Transport channels can be mapped to physical channels.

But there exist physical channels, which are generated at the Node B only, as can be seen on the nextfigures.

The details of the physical channels is described in detail within this module (see following pages).

Note: PDSCH & PCPCH have been removed from R5 specification, 25.301 v5.6.0

Physical Channels (PhyCH)


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P-CCPCHPCH

BCH

CTCH

DCCH

CCCH

PCCH

BCCH

DCH

CPICH

S-SCH

P-SCH

FACH

HS-

DSCH

AICH

HS-PDSCH

DPDCH

S-CCPCH

DTCH

PICH

Logical

Channels

Transport

Channels

Physical

Channels

E-AGCH

Channel Mapping DL (Network Point of View)

HS-SCCH

F-DPCH

E-RGCHE-HICH

DPCCH


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DCCH

DCH

DPDCH

DTCH

Logical

Channels

Transport

Channels

Physical

Channels

RACH

CCCH PRACH

DPCCH

Channel Mapping UL (Network Point of View)

E-DPCCH

E-DPDCHE-DCHHS-DPCCH


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Channel configuration examples

AMR call

The data transferred during AMR call consists of

Speech data

L3 signalling

L1 signalling

User data is transferred on DTCH logical channel

RT connection uses always DCH transport channel

DCH transport channel is mapped on DPCH (DPDCH + DPCCH)

AMR + PS call (Multi-RAB)

Additional stream of user data

NRT data

Also configurations with HS-DSCH possible

NRT PS call

Different configurations utilising DCH, FACH/RACH, HS-DSCH or HS-DSCH/E-DCHpossible


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Example Channel configuration during call

Logical

ChannelsTransport

Channels

Physical

Channels

Data

DCCH0-4

DCH2-4

DPDCH

DTCH1 DPCCH

RRC

signalling

Speech

data

DCH1

AMR speech connection utilises multiple transport channels

RRC connection utilises multiple logical channels

DPCCH for L1 control data

DCH5DTCH2NRT

data

AMR speech

+NRT data


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Part I: Channel Mapping

Part II: Transport Channel Formats Part III: Cell Synchronisation

Part IV: Common Control Physical Channels

Part V: Physical Random Access

Part VI: Dedicated Physical Channel Downlink

Part VII: Dedicated Physical Channel Uplink


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Transport Channel Formats

Transport Channels are used to exchange data between the MAC-layers in the UE and the RNC.

The data is hereby organised in Transport Blocks (TB).A Transport Block is the basic data unit.

The MAC layer entities use the services offered to them by the Physical layer to exchange TransportBlocks.

One Transport Block can be transmitted only over one Transport Channel. Several Transport Blockscan be simultaneously transmitted via a Transport Channel in one transport data unit to increase thetransport efficiency.

The set of all Transport Blocks, transmitted at the same time on the same transport channel (betweenthe MAC layer and the physical layer) is referred to as Transport Format Set (TFS).

Transport Blocks and Transport Block Sets are characterised by a set of attributes:

Transport Block Size

The transport block size specifies the numbers of bits of one Transport Block.

If several Transport Blocks are transmitted within one TBS, then all TBs have the same size.

Please note, that the transport block size among different TBSs which are transmitted at different times on one transporchannel - can vary.

Transport Block Set Size This attribute identifies the numbers of bits in one TBS.

It must be always a multiple of the transport block size, because all TBs transmitted in one TBS have the same size.

(continued on the next text slide)


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MAC Layer MAC Layer

PHY Layer PHY Layer L1

FP/AAL2

L1

FP/AAL2

TBS

TTI radio

frames in use

Transport Channel

UE RNC

TFITBS

The Transfer of Transport Blocks

TFI

TBS: Transport Block Set

TFI: Transport Format Indicator

Node B


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Transport Blocks and Transport Block Sets are characterised by a set of attributes (continued):

Transmission Time Interval (TTI)

The TTI specifies the transmission time distance between two subsequent TBSs, transferred

between the MAC and the PHY layer.In the PHY layer, the TTI also identifies the interleaving period. Following TTI periods are

currently specified:

- 2 ms (HS-DSCH), 10 ms, 20 ms, 40 ms, and 80 ms

Error Protection Scheme

When data is transmitted via a wireless link, it faces a lot of distortion and can thus easily

corrupted.

Redundancy is added to the user data to reduce the amount of losses on air.In UMTS, three error protection schemes are currently specified:

convolutionary coding with two rates: 1/2 and 1/3,

turbo coding (rate 1/3), and

no channel coding (this coding type is scheduled for removal from the UMTS

specifications).

Size of CRC

CRC stands for cyclic redundancy check. Each TBS gets an CRC.The grade of reliability depends on the CRC size, which can be 0, 8, 12, 16, and 24 bits.



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TB Transport Block TF Transport FormatTBS Transport Block Set TFS Transport Format Set

TFC Transport Format CombinationTFCS Transport Format Combination Set

DCH 2

DCH 1

TB TB TB

TB

TB

TB

TB

TB

TBS

TF

TFS

TFC

TFCS

TTI TTI

TTI

TTI

TTITTI

TB

TB

TB

Transport Formats


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The above description refers to a situation, where the MAC-layer hands the TBS to the PHY layer.

This happens in the UE. But TBSs are normally exchanged between the UE and the RNC. As a

consequence, the TBS must be transmitted over an AAL2 virtual channel between the RNC and the

Node B. The TBS is packet into a frame protocol defined for the traffic channel. Different TBSs can be transmitted in one Transport Channel.

How do MAC and PHY layer know, what kind of TBS they exchanged?

When a transport channel is setup or modified the allowed Transport Block Sets are specified.

Each allowed TBS gets a unique Transport Format Indicator (TFI).

All TFIs of a Transport Channel are summarised in the Transport Format Set (TFS). The TF consists of two parts (FDD mode):

Semi-static part

The attributes belonging to the semi-static part are set by the RRC-layer.

They are valid for all TBSs in the Transport Channel.

Semi-static attributes are the Transmission Time Interval (TTI), the error correction

scheme, the CRC size, and the static rate matching parameter (used by the PHY layer for

dynamic puncturing if the TBS is too long for the radio frame).

Dynamic part

The dynamic part comprises attributes, which can be changed by the MAC layer

dynamically.

The affected attributes are the Transport Block Size & Transport Block Set Size.



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MAC Layer

PHY Layer

RRC Layer

configuration

Semi-Static Part

TTI

Channel Coding

CRC size

Rate matching

Dynamic Part Transport Block Size

Transport Block Set Size

Transport Format

Example: semi-static part dynamic part:

- TTI = 10 ms

- turbo coding - transport block size: 64 64 64 128- CRC size = 0 - transport block set size: 1 2 4 2

- ...

TFI1 TFI2 TFI3 TFI4

TrCHs

Transport Formats

TrCH: Transport Channel

TBS: Transport Block Set

TFI: Transport Format Indicator


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T h e P H Y l a y e r c a n m u l t i p l e x s e v e r a l T r a n s p o r t

Coded Composite Transport Channel (CCTrCH).

This CCTrCH can be transmitted on one or several physical channels. Consequently, the TCSs ofdifferent Transport Channels can be found in one radio frame.

The Transport Format Combination Set (TFCS) lists all allowed Transport Format Combinations

(TFC).

A Transport Format Combination Indicator (TFCI) is then used to indicate, what kind of Transport

Format Combination is found on the radio frame. You can find TFCI-fields for instance in the S-CCPCH. The TFCS is set by the RRC protocol.

The table on the following slide lists the allowed Transport Formats for the individual Transport

Channels (FDD mode only).



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1...5000 bits

granularity: 1 bit

0...5000 bitsgranularity: 1 bit

0...5000 bits

granularity: 1 bit

246 bits

0...5000 bits

granularity: 1 bit

246 bits

1...200000 bits

granularity: 1 bit

0...200000 bitsgranularity: 1 bit

0...200000 bits

granularity: 1 bit

0...200000 bits

granularity: 1 bit

20 ms

10 ms

10, 20, 40& 80 ms

10 & 20

ms

10, 20, 40

& 80 ms

BCH

FACH

RACH

PCH

DCH

convolutional 1/2

convolutional 1/2

convolutional 1/2& 1/3; turbo 1/3

convolutional 1/2

convolutional 1/2

& 1/3; turbo 1/3

16

0, 8, 12,

16 & 24

0, 8, 12,16 & 24

0, 8, 12,

16 & 24

0, 8, 12,

16 & 24

Transport

Block Size

Transport

Block Set SizeTTI

coding types

and rates

CRC

size

Semi-static PartDynamic Part

3GPP TS 25.302 V5.9.0

Transport Format Ranges


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Example: Transport Formats in AMR call

The AMR codec was originally developed and standardized by the EuropeanTelecommunications Standards Institute (ETSI) for GSM cellular systems. It has been

chosen by the Third Generation Partnership Project (3GPP) as the mandatory codec forthird generation (3G) cellular systems. It supports 8 encoding modes with bit ratesbetween 4.75 and 12.2 kbps.

Feature of the AMR codec is Unequal Bit-error Detection and Protection (UED, UEP).

The UEP/UED mechanisms allow more speech over a lossy network by sorting thebits into perceptually more and less sensitive classes (A, B, C).

A frame is only declared damaged and not delivered if there are bit errors found in the mostsensitive bits (Class A).

Acceptable speech quality results if the speech frame is delivered with bit errors in the lesssensitive bits (Class B, C). Decoder uses error concealment algorithm to hide the errors.

On the radio interface, one Transport Channel is established per class of bits i.e. DCH Afor class A, DCH B for class B and DCH C for class C. Each DCH has a different transport

format combination set which corresponds to the necessary protection for thecorresponding class of bits as well as the size of these class of bits for the various AMRcodec modes.


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Example: Transport Formats in AMR call

DCH 1: AMR class Abits

TBS size: 1TB size: 39 bits

(SID)

TBS size = 0

(DTX)


TTI = 20 ms

TBS size = 0

(DTX)

DCH 2: AMR class Bbits

DCH 3: AMR class Cbits

Convolutional codingCoding rate: 1/3

TTI = 20 ms

Coding type: convolutionalCoding rate: 1/3

CRC size: 12 bits CRC size: 0 bits CRC size: 0 bits

TTI = 20 ms

Coding rate: 1/2Convolutional coding

DCH 24: RRCConnection

TBS size = 0

(DTX)

TBS size = 1TB size: 148 bits

TTI = 40 ms

Coding type: convolutionalCoding rate: 1/3

CRC size: 16 bits

TBS size:1TB size: 81 bits


TBS size = 0

(DTX)

12.2 kbit/s3.7 kbit/s

81+103+60 = 244

244 bits in 20 ms => 12.2 Kbps

If All 8 AMR modes should be supported + 1 mode for SID frames + 1 mode for DTX.

For dedicated signaling channel there should be possibility for 2 modes, e.g. on / off. This

will mean totally : 2*(8+1+1)=20 transport format combinations.


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Part II: Transport Channel Formats Part III: Cell Synchronisation






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Cell Synchronisation

When a UE is switched on, it starts to monitor the radio interface to find a suitable cell to camp on butit has to determine, whether there is a WCDMA cell nearby.

If a WCDMA cell is available, the UE has to be synchronised to the DL transmission of the system

information transmitted on the physical channel P-CCPCH before it can make a decision, in howfar the available cell is suitable to camp on.

Initial cell selection is not the only reason, why a UE wants to perform cell synchronisation. Thisprocess is also required for cell re-selection and the handover procedure.

Cell synchronisation is achieved in 3 steps*:

Step 1: Slot synchronisation D u r i n g t h e f i r s t s t e p o f t h e c e l l s e a r c h p r o c e d u r e t h e

synchronisation to a cell. This is typically done with a single matched filter (or any similar device) matched to the primary

synchronisation code which is common to all cells. The slot timing of the cell can be obtained by detecting peaks in thematched filter output.

Step 2: Frame synchronisation and code-group identification D u r i n g t h e s e c o n d s t e p o f t h e c e l l s e a r c h p r o c e d u r e , t

frame synchronisation and identify the code group of the cell found in the first step. This is done by correlating thereceived signal with all possible secondary synchronisation code sequences, and identifying the maximum correlationvalue. Since the cyclic shifts of the sequences are unique the code group as well as the frame synchronisation isdetermined.

Step 3: Scrambling-code identification During the third and last step of the cell search procedure, the UE determines the exact primary scrambling code used by

the found cell. The primary scrambling code is typically identified through symbol-by-symbol correlation over the CPICHwith all codes within the code group identified in the second step. After the primary scrambling code has been identified,the Primary CCPCH can be detected. And the system- and cell specific BCH information can be read.

If the UE has received information about which scrambling codes to search for, steps 2 and 3 abovecan be simplified.

* further Information about Primary- & Secondary Synchronisation

Channels and Code Groups can be found on the following pages


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Detect cells Acquire slot

synchronisation

Phase 1 P-SCH

Phase 2 S-SCH

Phase 3 P-CPICH

Acquire frame synchronisation

Identify the code group of thecell found in the first step

Determine the exact primary

scrambling code used by thefound cell

Measure level & quality of the

found cell

PriScrCode

WCEL; 0..511; 1; no default

(Range; Step; Default)


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Cell synchronisation is achieved with the Synchronisation Channel (SCH). This channel divides up into

2 sub-channels:

Primary Synchronisation Channel (P-SCH)

A time slot lasts 2560 chips.

The P-SCH only uses the first 10% of a time slot.

A Primary Synchronisation Code (PSC) is transmitted the first 256 chips of a time slot. This is the case

in every UMTS cell.

If the UE detects the PSC, it has performed TS and chip synchronisation.

Secondary Synchronisation Channel (S-SCH)

The S-SCH also uses only the first 10% of a timeslot

Secondary Synchronisation Codes (SSC) are transmitted.

There are 16 different SSCs, which are organised in a 10 ms frame (15 timeslots) in such a way, that

the beginning of a 10 ms frame can be determined, and 64 different SSC combinations within a 10 ms

frame are identified.

There is a total of 512 primary scrambling codes, which are grouped in 64 scrambling code families,

each family holding 8 scrambling code members.

T h e 1 5 S S C s i n o n e 1 0 m s f r a me i d e n t i f y t h e s c



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Cp = Primary Synchronisation CodeCs = Secondary Synchronisation Code

10 ms Frame

CP CP

2560 Chips 256 Chips

Cs1 Cs2 Cs15

Slot 0 Slot 1 Slot 14

CP CP CP

Cs1

Primary Synchronisation Channel (P-SCH)

Secondary Synchronisation Channel (S-SCH)

Slot 0

Synchronisation Channel (SCH)

PtxPr imarySCH

-35..15; 0.1; -3 dB(Range; Step; Default)

PtxSecSCH

-35..15; 0.1; -3 dB(Range; Step; Default)


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15

15

scrambling

code group

group 00

group 01

group 02

group 03

group 05

group 04

group 62

group 63

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

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

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

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

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

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

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

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

slot number

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

11

11 11

11 11

11 11

11 11

15

15

15

15 15

15

15

15 15

15 15

5

5

SSC Allocation for S-SCH

I monitorthe S-SCH

C Pil t Ch l (CPICH)


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With the help of the SCH, the UE was capable to perform chip, TS, and frame synchronisation.

E v e n t h e c e l l s s c r a m b l i n g c o d e g r o u p i s k n o

B u t i n t h e i n i t i a l c e l l s e l e c t i o n p r o c e s s , i t

There is one primary scrambling code in use over the entire cell, and in neighbouring cells, different

scrambling codes are in use.

There exists a total of 512 primary scrambling codes.

The CPICH is used to transmit in every TS a pre-defined bit sequence with a spreading factor 256.

The CPICH divides up into a mandatory Primary Common Pilot Channel (P-CPICH) and optional

Secondary CPICHs (S-CPICH).

The P-CPICH is in use over the entire cell and it is the first physical channel, where a spreading code

is in use.

A s p r e a d i n g c o d e i s t h e p r o d u c t o f t h e c e l l

The channelisation code is fixed: Cch,256,0. i.e., the UE knows the P-C P I C H s c h a n n e

and it uses the P-C P I C H t o d e t e r m i n e t h e c e l l s p r i m a r y

The P-CPICH is not only used to determine the primary scrambling code. It also acts as:-

phase reference for most of the physical channels,

measurement reference in the FDD mode (and partially in the TDD mode).

There may be zero or several S-C P I C H s . E i t h e r t h e c e l l s p r i m a r

scrambling codes can be used. In contrast to the P-CPICH, it can be broadcasted just over a part ofthe cell.

Common Pilot Channel (CPICH)

P i C Pil t Ch l (P CPICH)


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CP



P-CPICH

10 ms Frame

applied speading code =

c e l l s p r i ma r y s c r a mb l i n g c o d eCch,256,0

Phase reference

Measurement reference

P-CPICHCell scrambling

code? I get it with

trial & error!

Primary Common Pilot Channel (P-CPICH)

PtxPr imaryCPICH

-10..50; 0.1; 33 dBm


(20 W sector)

CPICH M t R f


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The UE has to perform a set of L1 measurements, some of them refer to the CPICH channel:

CPICH RSCP

RSCP stands for Received Signal Code Power.

The UE measures the RSCP on the Primary-CPICH.

The reference point for the measurement is the antenna connector of the UE.

The CPICH RSCP is a power measurement of the CPICH.

The received code power may be high, but it does not yet indicate the quality of the received

signal, which depends on the overall noise level.

UTRA carrier RSSI.

RSSI stands for Received Signal Strength Indicator.

The UE measures the received wide band power, which includes thermal noise and receiver

generated noise.

The reference point for the measurements is the antenna connector of the UE.

CPICH Ec/No

T h e C P I C H E c / N o i s u s e d t o d e t e r m i n e t h e q u a

I t g i v e s t h e r e c e i v e d e n e r g y p e r r e c e i v e d c h i

T h e q u a l i t y i s t h e p r i m a r y C P I C H s s i g n a l s

(Please note, that transport channel quality is determined by BLER, BER, etc. )

If the UE supports GSM, then it must be capable to make measurements in the GSM bands, too. The

measurements are based on the GSM carrier RSSI

The wideband measurements are conducted on GSM BCCH carriers.

CPICH as Measurement Reference

P CPICH as Measurement Reference


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Received Signal Code Power (in dBm)CPICH RSCP

received energy per chip divided by the power density in the band (in dB)CPICH Ec/No

received wide band power, including thermal noise and noise generated in the

receiver

UTRA carrier

RSSI

CPICH Ec/No =CPICH RSCP

UTRA carrier RSSI

CPICH Ec/No

0: < -24

1: -23.5

2: -23

3: -22.5

...

47: -0.548: 0

49: >0

Ec/No values in dB

CPICH RSCP

-5: < -120

-4: -119

:

0: -115

1: -114

:89: -26

90: -25

9 1 : -25

RSCP values in dBm

GSM carrier RSSI

0: -110

1: -109

2: -108

:

71: -39

72: -38

73: -37

RSSI values in dBm

P-CPICH as Measurement Reference

Primary Common Control Physical Channel (P CCPCH)


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T h e U E k n o w s t h e c e l l s p r i m a r y s c r a mb l i n g c o d

It now wants to gain the cell system information, which is transmitted on the physical channel P-

CCPCH.

The channelisation code of the P-CCPCH is also known to the UE, because it must be Cch,256,1

in

every cell for every operator.

By reading the cell system information on the P-CCPCH, the UE learns everything about the

configuration of the remaining common physical channels in the cell, such as the physical channels for

paging and random access.

As can be seen from the P-C C P C H s c h a n n e l i s a t i o n c o d e , t h e d

fixed.

The SCH is transmitted on the first 256 chips of a timeslot, thus creating here a peak load.

The cell system information is transmitted in the timeslot except for the first 256 chips. By doing so, a

high interference and load at the beginning of the timeslot is avoided.

This leads to a net data rate of 27 kbps for the cell system information.

Channel estimation is done with the CPICH, so that no pilot sequence is required in the P-CCPCH.

(The use of the pilot sequence is explained in the context of the DPDCH later on in this

document.)

T h e r e a r e a l s o n o p o w e r c o n t r o l ( T P C ) b i t s t r a

Primary Common Control Physical Channel (P-CCPCH)

Primary Common Control Physical Channel (P CCPCH)


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CP



P-CCPCH

10 ms Frame

P-CCPCHFinally, I get the

cell system

information

channelisation code: Cch,256,1 no TPC, no pilot sequence

27 kbps (due to off period)

organised in MIBs and SIBs

Primary Common Control Physical Channel (P-CCPCH)

PtxPr imaryCCPCH

-35..15; 0.1; -5 dB


Node Synchronisation


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SRNC

time

3112

3113

3114

3115

3116

3117

3118

RFN

time

128

129

130

131

132

133

134

BFN

135

T1

(T4)

T2

T3

(T4 T1) (T3 T2)= Round Trip Delay

(RTD) determination

for DCH services

T1, T2, T3

range: 0 .. 40959.875 ms

resolution: 0.125 ms

DL offset

UL offset

user plane defined on

DCH, FACH & DSCH

BFN:

Node B Frame

Number counter

0..4095 frames

RFN:

RNC Frame

Number counter

0..4095 frames

Node Synchronisation

Node B

Cell Synchronisation and Sectorised Cells


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A timing reference is required by the Node Synchronisation:

Node B Frame Number (BFN)

The BFN is a counter at the Node B, based on the 10 ms framing structure of WCDMA.

RNC Frame Number (RFN)

The RFN is a counter at the RNC, based on the 10 ms framing structure of WCDMA.

Cell System Frame Number (SFN)

This is a counter for each cell, and is broadcasted on the P-CCPCH.

With one Node B, several (sector) cells can be deployed. These cells overlap.

If the SCH is transmitted at the same tame in all the sector cells of the Node B, and when a UE is in

the overlapping coverage area of two of these cells, it will have difficulties to synchronise to one cell. As a consequence, an offset can be used for neighbouring cells of one Node B: T_cell.

T_cell is a timing delay for the starting time of the physical channels SCH, CPICH, BCCH relative

t o t h e N o d e B s t i m e r B F N .

The timing delay is a multiple (0..9) of 256 chips due to of the length of a SCH burst.

T h e c e l l s t i m i n g i s i d e n t i f i e d w i t h t h e c o u n

(Please note, that this description only applied for the FDD mode!)

Cell Synchronisation and Sectorised Cells

Cell Synchronization and Sectorised Cells


37/97


Node B with three

sectorised cells

cell1

cell2

cell3

1 TS

BFN

SCH

SCH

SCH

SCH

SCH

SCH

SCH

SFN = BFN + T_cell1

SFN = BFN + T_cell2

SFN =

BFN + T_cell3

T_cell3

T_cell1

T_cell2

SFN: Cell System Frame Numberrange: 0..4095 frames

T_cell: n 256 chips, n = 0..9

cell3 cell2

cell1

SCH

Cell Synchronization and Sectorised Cells

TcellWCELL; 0..2304 chip;

256 chip; no default

Tcell: Timing delay used for defining the start of SCH, P-

CPICH, P-CCPCH in a cell relative to BFN

BFN: Node B Frame Number

RFN: RNC Frame Number

SFN: Cell Frame Number

The Physical Layer Rel 99


38/97




Part II: Transport Channel Formats

Part III: Cell Synchronisation





Secondary Common Control Physical Channel

(S CCPCH)


39/97


The S-CCPCH can be used to transmit the transport channels

Forward Access Channel (FACH) and

Paging Channel (PCH).

More than one S-CCPCH can be deployed.

FACH & PCH information can multiplexed on one S-CCPCH (even on the same 10 ms frame), or they

can be carried on different S-CCPCH.

The first S-CCPCH must have a spreading factor of 256, while the SF of the remaining S-CCPCHs

can range between 256 and 4.

UTRAN determines, whether a S-CCPCH has the TFCI (Transport Format Combination Indicator)

included. Please note, that the UE must support both S-CCPCHs with and without TFCI.

(S-CCPCH)

Secondary Common Control Physical Channel (S-CCPCH) (1/7)


40/97


Slot 0 Slot 1 Slot 2 Slot 14

10 ms Frame

S-CCPCH

TFCI

(optional)Data Pilot bits

carries PCH and FACH

Multiplexing of PCH and FACH on one

S-CCPCH, even one frame possible

with and without TFCI (UTRAN set)

SF = 4..256 (18 different slot formats

no inner loop power control

Secondary Common Control Physical Channel (S CCPCH) (1/7)

S-CCPCH (2/7): Number of S-CCPCHs


41/97


S CCPCH (2/7): Number of S CCPCHs

The S-CCPCH (Secondary Common Control Physical Channel) carries FACH & PCH

transport channels

Parameter WCEL:Nb rOfSCCPCHs(Number of SCCPCHs) tells how many SCCPCHswill be configured for the cell. (1, 2 or 3)

If only 1 SCCPCHis used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH),

FACH-u (containing DTCH) and PCH. FACH and PCH multiplexed onto the same SCCPCH.

If 2 SCCPCHsare used in a cell, the first SCCPCH will carry FACH-u & FACH-c and the second

SCCPCH will always carry PCH only.

If 3 SCCPCHsare used in a cell, the third SCCPCH will carry FACH-s (containing CTCH) &FACH-c idle (containing CCCH & BCCH). The third SCCPCH is only needed when Service Area

Broadcast (SAB) is active in a cell.

NbrOfSCCPCHs

WCEL; 1..3; 1; 1(Range; Step; Default)

S-CCPCH (3/7): Configuration 1


42/97


( ) g

If only 1 SCCPCH is used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH), FACH-u

(containing DTCH) and PCH. FACH and PCH multiplexed onto the same SCCPCH.

the PCH bit rate is limited to 8 kbps

the PCH always has priority

the SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)

Logical channel

Transport channel

Physical channel

DTCH DCCH CCCH BCCH PCCH

FACH-u FACH-c PCH

SCCPCH 1

SF 64

PtxSCCPCH1Transmission Power of SCCPCH1WCEL; -35..15; 0.1; 0 dB


S-CCPCH (4/7): Configuration 2 a & b


43/97


( ) g

If 2 SCCPCHs are used in a cell, the first SCCPCH will carry FACH-u & FACH-c and the second

SCCPCH will always carry PCH only.

PCH bit rate limited to 8 kbps (RU10 & earlier) or can be extended

to 24 kbps (RU20 feature RAN 1202: 24 kbps Paging Channel)

if PCH24kbps enabled, NbrOfSCCPCHs m u s t b e s e t t o 2 o r 3

Logical

channel

Transport

channel

Physical

channel

DTCH DCCH CCCH BCCH PCCH

FACH-u FACH-c PCH

SCCPCH 1 SCCPCH 2SF 64 SF 256

PCH24kbpsEnabled

WCEL; 0 (Disabled), 1 (Enabled);default: 0 (Disabled)

SF 128or

PtxSCCPCH2

used for 8 kbps pagingWCEL; -35..15; 0.1; -5 dB

PtxSCCPCH2SF128used for 24 kbps paging

WCEL; -35..15; 0.1; -2 dB

S-CCPCH (5/7): Configuration 3a & b


44/97


Logical channel

Transportchannel

Physicalchannel

DTCH DCCH CCCH BCCH CTCH

FACH-u PCHFACH-s

SCCPCHconnected

SCCPCHidle

PCCH

FACH-c FACH-c

SCCPCHpage

For SAB

( ) g

if 3 SCCPCHs are used in a cell, the third SCCPCH will carry FACH-s (containing CTCH) & FACH-c

idle (containing CCCH & BCCH). The third SCCPCH is only needed when Service Area Broadcast

(SAB) is active in a cell.

SF 64 SF 128 SF 256

SF 128orPtxSCCPCH3

WCEL; -35..15; 0.1; -2 dB

S-CCPCH (6/7): Summary Power Setting


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The power of SCCPCHs are set relative to CPICH transmission power, but it is based on the bitrate.

The SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)

The SF for SCCPCH, which is carrying PCH only is 256 (15ksps) or 128 (30ksps)

The SF for SCCPCH, which is carrying FACH-s/FACH-c idle for SAB, is 128 (30ksps)

Recommended value of the SCCPCH Tx power is depended on the number of SCCPCHs:

WCEL:PtxSCCPCH1(SF=64) for PCH/FACH or standalone FACH

WCEL:PtxSCCPCH2(SF=256) for Standalone PCH (8 kbps paging)

WCEL:Ptx SCCPCH2SF128(SF=128) for Standalone PCH (24 kbps paging)

WCEL:PtxSCCPCH3(SF=128) for SAB

PtxSCCPCH1

WCEL; -35..15; 0.1; 0 dB


PtxSCCPCH3

WCEL; -35..15; 0.1; -2 dB

SF: Spreading Factor

PtxSCCPCH2used for 8 kbps paging

WCEL; -35..15; 0.1; -5 dB

PtxSCCPCH2SF128used for 24 kbps paging

WCEL; -35..15; 0.1; -2 dB

S-CCPCH (7/7) in NSN RAN


46/97


FACH-uFACH-c

(connected)FACH-c

(idle)

TFS

TTI

Channelcoding

CRC

0: 0x360 bits

(0 kbit/s)

1: 1x360 bits

(36 kbit/s)

10 ms

TC 1/3

16 bit

0: 0x168 bits

(0 kbit/s)

1: 1x168 bits

(16.8 kbit/s)

2: 2x168 bits

(33.6 kbit/s)

10 ms

CC 1/2

16 bit

0: 0x168 bits

(0 kbit/s)

1: 1x168 bits

(16.8 kbit/s)

10 ms

CC 1/3

16 bit

FACH-s

0: 0x168 bits

(0 kbit/s)

1: 1x168 bits

(16.8 kbit/s)

10 ms

CC 1/3

16 bit

PCH

0: 0x80 bits

(0 kbit/s)

1: 1x80 bits

(8 kbit/s)

2: 1x240 bits

(24 kbps)

10 ms

CC 1/2

16 bit

The Paging Process


47/97


Paging Indicator Channel (PICH)

UMTS provides the terminals with an efficient sleep mode operation. The UEs do not have to read and

process the content, transmitted during their paging occasion on their S-CCPCH.

Each S-CCPCH, which is used for paging, has an associated Paging Indicator Channel (PICH).

A PICH is a physical channel, which carries paging indicators. A set of (paging indicator) bits within the PICH indicate to a UE, whether there is a paging occasion for

it. Only then, the UE listens to the S-CCPCH frame, which is transmitted 7680 chips after the PICH

frame in order to see, whether there is indeed a paging message for it.

The PICH is used with spreading factor 256.

300 bits are transmitted in a 10 ms frame, and 288 of them are used for paging indication.

The UE was informed by the BCCH, how many paging indicators exist on a 10 ms frame.

The number of paging indicator Np can be 18, 36, 72, and 144, and is set by the operator as part of the networkplanning process.

The higher Np, the more paging indicators exist, the more paging groups exist, among which UEs can be

distributed on.

Consequently, the lower the probability, that a UE reacts on a paging indicator, while there is no paging message

in the associated S-CCPCH frame.

But a high number of paging indicators results in a comparatively high output power for the PICH, because less

bits exists within a paging indicator to indicate the paging event.

The operator then also has to consider, if he has to increase the number of paging attempts.

How does the UE and UTRAN determine the paging indicator (PI) and the Paging Occasion?

This is shown in one of the next slides.

S-CCPCH & associated PICH


48/97


PICH frame

S-CCPCH frame,

associated with PICH frame

PICH

= 7680chips

b287 b288 b299b286b0 b1

for paging indication no transmission

# of paging

indicators per frame

(Np)

18

36

72

144

S-CCPCH

NpRepetition of PICH bits18, 36, 72 144

PtxPICH-10..5; 1; -8 dB


S-CCPCH and the Paging Process


49/97


The network has detected, that there is data to be transmitted to the UE.

Both in the RRC idle mode and in the RRC connected mode (e.g. in the sub-state CELL_PCH) a UE

may get paged. But how does the mobile know, when it was paged?

A n d i n o r d e r t o s a v e b a t t e r y p o w e r , w e d o n

channel instead, we want to have discontinuous reception (DRX) of paging messages. But when and where does the UE listen to the paging messages?

Cell system information is broadcasted via the P-CCPCH.

The cell system information is organised in System Information Blocks (SIB).

SIB5 informs the mobile phones about the common channel configuration, including a list of

S-CCPCH descriptions.

The first 1 to Kentries transmit the (transport channel) PCH, while the remaining S-CCPCH

in the list hold no paging information. The UE determines the S-CCPCH, where it is paged, by its IMSI and the number of PCH/S-CCPCHs

carrying S-CCPCHs K.

Wh e n p a g i n g t h e U E , t h e R N C k n o w s t h e U E s I M S

the correct PCH transport channel.

Discontinuous Reception (DRX) of paging messages is supported. A DRX cycle length khas to be set in the network planning process for the cs domain, ps domain, and

UTRAN. kranges between 3 and 9. If for instance k=6, then the UE is paged every 2k = 640 ms.

If the UE is in the idle mode, it takes the smaller k-value of either the cs- or ps-domain.

If the UE is in the connected mode, it has to select the smallest k-value of UTRAN and the CN, it is not

connected to.

UTRANS-CCPCH & Paging Process


50/97


Node B

UTRANP-CCPCH/BCCH (SIB 5)

UE

common

channel

definition,including

S-CCPCH carrying 1 PCH



S-CCPCH without PCH

S-CCPCH without PCH

a lists of

Index of S-CCPCHs

0

1

K-1

U E s p a g i n g c h a n n e l :

Index = IMSI mod K

e.g. if IMSI mod K= 1

m y p a g i n g

c h a n n e l

RNC

Paging & Discontinuous Reception (FDD mode)


51/97


2k frames

k = 3..9

Duration:

CN domain specific

DRX cycle lengths

(option)

UE

CS Domain PS Domain

Update:

a) derived by NAS

negotiation

b) otherwise:

system info

Update:

locally with

system info

k1 k2

UTRAN

Update:

a) derived by NAS

negotiation

b) otherwise:

system info

k3

RRC connected

mode

stores

if RRC idle:

UE DRX cycle length is

min (k1, k2)

if RRC connected:

UE DRX cycle length is

min (k3, kdomain with no Iu-signalling connection)

Example with

two CN domains

UTRAN_DRX_length80; 160; 320; 640; 1280;

2560; 5120 ms

CNDRXLength640; 1280; 2560; 5120 ms

Paging Indicator & Paging Occasion (FDD mode)


52/97


UE

my paging

indicator (PI)

PI = ( IMSI div 8192) mod Np

DRX index

number of paging indicators

18, 36, 72, 144

Paging Occasion = (IMSI div K) mod (DRX cycle length)

+ n * DRX cycle length

UE

When willI get paged?number of S-CCPCH with PCH

FDD

mode

Example Paging instant and group calculation


53/97


UE calculates paging instant based on following information as presented before

IMSI

Number of S-CCPCH (K)

DRX cycle length (k)

Np

User are distributed to different paging groups based on their IMSI. Paging group

size can be calculated based on

Number of S-CCPCH (K)

DRX cycle length (k)

Np

Paging group size affects on how often UE has to decode paging message from

S-CCPCH Power consumption

Example Paging instant & group calculation


54/97


K (Number of S-CCPCH with PCH) 1

k (DRX length) 6

DRX cycle length 64 framesIMSI 358506452377

Which S-CCPCH #? 0

IMSI div K 358506452377

When (Paging occation, SFN)? 25 + n*DRX cycle length

Np 72 PIs/frame

DRX Index 43762994My PI? 26

Number of subsc. In LA/RA 100000

Number of subsc. Per S-CCPCH 100000

Number of subsc. Paging occation (PICHframe) 1562.5

Number of subsc. Per PI 21.7



55/97









I h d i i i d b h UE h i l h l i l d

Random Access


56/97


In the random access, initiated by the UE, two physical channels are involved:

Physical Random Access Channel (PRACH)

The physical random access is decomposed into the transmission of preambles in the UL.

Each preamble is transmitted with a higher output power as the preceding one. After the transmission of a preamble, the UE waits for a response by the Node B.

This response is sent with the physical channel Acquisition Indication Channel (AICH), telling

the UE, that the Node B as acquired the preamble transmission of the random access.

Thereafter, the UE sends the message itself, which is the RACH/CCCH of the higher layers.

The preambles are used to allow the UE to start the access with a very low output power.

If it had started with a too high transmission output power, it would have caused interference

to the ongoing transmissions in the serving and neighbouring cells. Please note, that the PRACH is not only used to establish a signalling connection to UTRAN, it

can be also used to transmit very small amounts of user data.

Acquisition Indication Channel (AICH)

This physical channel indicates to the UE, that it has received the PRACH preamble and is now

waiting for the PRACH message part.

Random Access the Working Principle


57/97


UE

No response

by the

Node B

No response

by the

Node B

I just detected

a PRACH preamble

OLA!

Node B

Th ti f th PRACH b d t d (SIB5 SIB6)

Random Access Timing


58/97


The properties of the PRACH are broadcasted (SIB5, SIB6).

The candidate PRACH is randomly selected (if there are several PRACH advertised in the cell) as well

as the access slots within the PRACH.

15 access slots are given in a PRACH, each access slot lasting two timeslots or 5120 chips.

In other words, the access slots stretch over two 10 ms frames. A PRACH preamble, which is transmitted in an access slot, has a length of 4096 chips.

Also the AICH is organised in (AICH) access slots, which stretch over two timeslots.

AICH access slots are time aligned with the P-CCPCH.

The UE sends one preamble in UL access slot n.

It expects to receive a response from the Node B in the DL (AICH) access slot n,p-a chips later on.

If there is no response, the UE sends the next preamble p-p chips after the first one. The maximum numbers of preambles in one preamble access attempt can be set between 1 and 64.

The number of PRACH preamble cycles can be set between 1 and 32.

If the AICH_Transmission_Timing parameter in the SIB is set to BCCH SIB5 & SIB6 to

0 = then, the minimum preamble-to-preamble distance is 6 access slots, the minimum

preamble-to-message distance is 6 access slots, and the preamble-to-acquisition indication

is 3 timeslots.

1 = then, the minimum preamble-to-preamble distance is 8 access slots, the minimumpreamble-to-message distance is 8 access slots, and the preamble-to-acquisition indication

is 4 timeslots.

SFN mod 2 = 0 SFN mod 2 = 0SFN mod 2 = 1

Random Access Timing


59/97


SFN mod 2 = 0 SFN mod 2 = 0SFN mod 2 = 1

P-CCPCH

AICH access

slots 0 1 1282 1175 964 13103 14 0 1 2 75 643

5120

chips

Preamble

5120 chips

Preamble

AS # i

4096 chips

preamble-to-preamble

distance p-p

UE point of view

PRACH

access slots

AICHaccess slots

Message

part

preamble-to-message

distance p-m

Acquisition

Indication

preamble-to-AI

distancep-a

AS # i

TS 25.211:

Preamble-to-Preamble distance p-p p-p,min = 6 / 8 Slots

Preamble-to-AI distance p-a = 3 / 4 Slots

Preamble-to-Message distance p-m = 6 / 8 Slots

Broadcasted by P-CCPCH;

NSN (WCEL):

AICHTraTime= 0, 1; 0

RACH Sub channels

RACH Sub-channels and Access Service Classes


60/97


RACH Sub-channels

RACH sub-channels were introduced to define a sub-set of UL access slots. A total number of 12 RACH sub-channels exist, numbered from 0 to 11. The PRACH access slots are numbered relative to the AICH assess slot.

The offset is given by p-a (see preceding slides). The AICH is transmitted synchronised to the P-CCPCH.

An access slot of sub-channel #i is using access slot #i, when SFN mod 8 = 0 or 1. It is then using every

12th access slot following access slot #i.

You can see in the figure on the right hand side all existing sub-channels and the timeslots, they are

using.

Access Classes (AS) and Access Service Classes (ASC)

Access Service Classes were introduced to allow priority access to the PRACH resources, by

associating ASCs to specific access slot spaces (RACH sub-channels) and signatures.

8 ASC can be specified by the operator; The UE determines the ASC and its associated resources from

SIB5 & SIB7.

The mapping of the subscribers access classes (1..15) is part of the SIB5.

RACH Access Slot Sets

Two access slot set were specified:

Access slot set 1 holds PRACH access slots 1 to 7, i.e. the PRACH access slots, whose corresponding

AICH access slots begin in a P-CCPCH with a SFN modulo 2 = 0. Access slot set 2 holds PRACH access slots 8 to 15, i.e. the PRACH access slots, whose

corresponding AICH access slots begin in a P-CCPCH with a SFN modulo 2 = 1.

SFN d 8 f th

PRACH Sub-channels and Access Service Classes (ASC)


61/97


SFN mod 8 of the

corresponding

P-CCPCH frame

0

1

2

3

4

5

6

7

0

12

9

6

3

1

13

10

7

4

2

14

11

8

5

3

0

12

9

6

4

1

13

10

7

5

2

14

11

8

6

3

0

12

9

7

4

1

13

10

8

5

2

14

11

9

6

3

0

12

10

7

4

1

13

Sub-channel number

1 2 3 4 5 6 7 8 9 10 11

11

8

5

2

14

0

(cited from TS 25.214 V5.11.0, chap. 6.1.1)

Node B

BCCH (SIB 5, SIB 7)

UE ASCs & their PRACH access resources + signatures,

AC mapping into ASCs

In the PRACH preamble, a random preamble code is used.

PRACH Preamble


62/97


In the PRACH preamble, a random preamble code is used.

This code is composed from a

Preamble Scrambling Code and a

Preamble Signature

There is a total of 16 preamble signatures of 16 bit length, which is repeated 256 times within one

preamble.

When monitoring the cell system information, the UE gets the information, which of the signatures are

available for use in the cell. (see IE PRACH info)

There are 8192 preamble scrambling codes, which are constructed from the long scrambling code

sequences. The PRACH preamble scrambling codes are organised in 512 groups, with each group holding 16

members.

There are also 512 primary scrambling codes available in UMTS, and one of them is in use in the cell.

If the primary scrambling code sis in use in the cell, then only the PRACH preamble scrambling codes

belonging to PRACH preamble scrambling code group scan be used for random access.

Consequently, 16 PRACH preamble scrambling codes are left, and the BCCH is used to inform the

UE, which PRACH preamble scrambling codes can be used. (see IE PRACH info)

UTRANBCCH

PRACH Preamble


63/97


Node B

BCCH

UE RNC

Pi Pi Pi Pi

Preamble Signature

(16 different versions)

16 chip

256 repetitions

PRACH Preamble Scrambling Code

512 groups, each with 16

preamble scrambling codes C e l l s p r i ma r y s c

associated with preamble

scrambling code group

available signatures forrandom access

available preamble

scrambling codes

available spreading

factor

available sub-channels

etc.

AllowedPreambleSignatures

WCEL; 16-bit field;

0 . 0 1 1 1 1; max. 4

signatures allowed

The length of the PRACH message part can be 10 ms or 20 ms.

PRACH Message Part


64/97


The length of the PRACH message part can be 10 ms or 20 ms.

Its length is set as Transmission Time Interval (TTI) value by the higher layers.

UL, we apply code multiplexing.

L1 Control data are transmitted with SF 256, while message data can be transmitted with SF 256,

128, 64 or 32. The message data contains the information, given by the RACH.

The control data contains 8 known pilot bits / slot. 15 different pilot bit sequences exist they are

associated with the slot, where the transmission takes place within the 10 ms message frame. 2 bits in

the control data carry TFCI bits / slot.

Which spreading code is allocated to the message part?

T h e me s s a g e p a r t s c h a n n e l i s a t i o n c o d e i s d e t ein the preamble.

16 different signatures exist, and each can be correlated to a channelisation code in the

channelisation code tree with spreading factor 16.

The channelisation codes are calculated like this:

Each signature has a number k, with 0 k 15.

For the control data, the channelisation code CCH,256,n is used, with n = 16*k + 15.

For the message data, the channelisation code CCH,SF,m is used, with m = SF*k/16. The scrambling code is the same, which was used for the PRACH preamble.

10 ms Frame

PRACH Message Part


65/97



RACH data

L1 control data 8 Pilot bits (sequence depends on slot number) 2 TFCI bits

data

SF = 256

channelisation code:CCH,256,16*k+15, with

k = signature number

SF = 256, 128, 64, or 32

channelisation code:

CCH,SF,SF*k/16, with

k = signature number

Scrambling code =

PRACH preamble scrambling code

When it comes to the random access, two questions have to be asked:

PRACH Power Setting


66/97


What kind of output power does the UE select for the first preamble?

And how does the output power change with the subsequent preambles and the message part?

Open Loop Power Control The output power for the first PRACH preamble is based in parts on broadcasted parameters (SIB6, if

missing, from SIB5; and SIB7).

T h e U E a c q u i r e s t h e N o d e B s P r i m a r y C P I C H T X

I n t e r f e r e n c e l e v e l .

The UE also determines the received CPICH RSCP (variable CPICH_RSCP).

Then, it calculates the power for the first preamble:

Preamble_Initial_Power = Primary CPICH TX power CPICH_RSCP + UL interference+ Required received C/I

T h e R e q u i r e d r e c e i v e d C / I i s a n U T R A N p a

range: -35 ... -10 dB, step 1 dB default: -25dB).

T h e U L I n t e r f e r e n c e i s m e a s u r e d b y t h e N-CCPCH

to the UEs.

The power ramp steps from one preamble to the next can be set between 1 and 8 dB (step size 1dB).

The power offset between the last PRACH and the PRACH control message can be set between5

and 10 dB (step size 1dB).

The gain factor cis used for the PRACH control part.

Preamble_Initial_Power =

Primary CPICH TX power

CPICH RSCP

PRACH Power SettingPRACHRequiredReceivedCI

WCEL: -35..-10; 1; -25 dB


67/97


CPICH_RSCP

+ UL interference

+ Required received C/I

Downlink / BS

P reamble 1 Mes sage part

. .

P reamble n

PRACH_preamble_retrans:

The maximum number of preambles

allowed in 1 preamble ramping cycle

RACH_tx_Max: # of preamble powerramping cycles that can be done

before RACH transmission failure isreported,

UEtxPowerMaxPRACH

WCEL: -50..33; 1; 21 dBm

PRACH_preamble_retrans

WCEL: 1..64; 1; 8

PowerRampStep

PRACHpreamble

WCEL: 1..8; 1; 2 dB

Uplink / UE

PowerOffset

LastPreamble

PRACHmessage

WCEL:

-5..10; 1; 2 dB

RACH_tx_Max

WCEL: 1..32; 1; 8(Range, Steps; Default)

The AICH is used to indicate to UEs, that their PRACH preamble was received, and that the Node B is



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expecting to receive the PRACH message part next.

The AICH returns an indicator of signature s, which was used in the PRACH preamble.

Spreading factor is fixed to 256 for the AICH.

The AICH is transmitted via 15 access slots, each lasting 5120 chips. Consequently, the AICH access slots are distributed over two consecutive 10 ms frames.

Similar to the PRACH preamble, only 4096 chips are used to transmit the Acquisition Indicator part.

32 real value symbols are transmitted.

Each real value is calculated by a sum of AIsbs,j.

AI is an acquisition indicator for signature s.

If signature s is positively confirmed, Ais is set to +1; a negative confirmation results in1; if

signature s is not part of the active signature set, then Ais is set to 0. bs,j stands for signaturepattern j, with j = 0..31.

If more than one PRACH preamble signatures within one PRACH access slot is detected correctly,

the Node B sends the AIs of all the detected signatures simultaneously in the 1st or 2ndAICH

access slot after the PRACH access slot.

If the number of correctly detected signatures is higher than the Node B's capability to

simultaneously decode the PRACH message parts, a negative AIs is used for generating the AIs

for those PRACH messages, which can not be decoded within the default message parttransmission timing.

A negative AI indicates to the MS that it shall exit the random access procedure. The Node B 's capability to decode the PRACH message parts is determined in the RNC and

transmitted to the Node B.

20 ms Frame



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Access Slot 0 Access Slot 1 Access Slot 2 Access Slot 14

a0 a1 a2 a29 a30a31

15

0

js,sj bAIas

AICH signature pattern (fixed)

Acquisition Indicator

+1 if signature s is positively confirmed

-1 if signature s is negatively confirmed

0 if signature s is not included in the

set of available signatures

PtxAICH

-22..5; 1; -8 dB(Range; Step; Default)

Summary of RACH procedure

1 D d f BCCH

(Adopted from TS 25.214)


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1- Decode from BCCH

Available RACH spreading factors

RACH scrambling code number

UE Access Service Class (ASC) info Signatures and sub-channels for each ASC

P o w e r s t e p , R A C H C / I r e q u i r e me n t = C o n s t a n t , B S

2 Calculate initial preamble power

3 Calculate available access slots in the next full access slot set and select randomly one of those

4 Select randomly one of the available signatures

5 Transmit preamble in the selected access slot with selected signature

6 Monitor AICH IF no AICH

Increase the preamble power

Select next available access slot & Go to 3

IF negative AICH or max. number of preambles exceeded Exit RACH procedure

IF positive AICH Transmit RACH message with same scrambling code and channelisation code related to signature



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Part VI: Dedicated Physical Channel - Downlink

Part VII: Dedicated Physical Channel - Uplink

The DL DPCH is used to transmit the DCH data.

Control information and user data are time multiplexed

Downlink Dedicated Physical Channel (DPCH)


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Control information and user data are time multiplexed.

The control data is associated with the Dedicated Physical Control Channel (DPCCH), while the user

data is associated with the Dedicated Physical Data Channel (DPDCH).

The transmission is organised in 10 ms radio frames, which are divided into 15 timeslots. The timeslot length is 2560 chips. Within each timeslot, following fields can be found:

Data field 1 and data field 2, which carry DPDCH information

Transmission Power Control (TPC) bit field

Transport Format Combination Indicator (TFCI) field, which is optional

Pilot bits

The exact length of the fields depends on the slot format, which is determined by higher layers.

The TFCI is optional, because it is not required for services with fixed data rates.

Slot format are also defined for the compressed mode; hereby different slot formats are in used, when

compression is achieved by a changed spreading factor or a changed puncturing scheme.

The pilot sequence is used for channel estimation as well as for the SIR ratio determination within the

inner loop power control.

The number of the pilot bits can be 2, 4, 8 and 16 it is adjusted with the spreading factor.

A similar adjustment is done for the TPC value; its bit numbers range between 2, 4 and 8.

The spreading factor for a DPCH can range between 4 and 512. The spreading factor can be changed

every TTI period.

Superframes last 720 ms and were introduced for GSM-UMTS handover support.

Superframe = 720 ms

Downlink Dedicated Physical Channel (DPCH)


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10 ms Frame

TPC

bitsPilot bits

TFCI

bits(optional)

Data 2 bitsData 1 bits

DPDCHDPDCH DPCCH DPCCH

Radio Frame

0

Radio Frame

1

Radio Frame

2

Radio Frame

71

17 different slot formats

Compressed mode slot

format for changed SF &

changed puncturing

Power offsets for the optional TFCI, TPC and pilot bits have to be specified during the radio link setup.

Power Offsets for the DPCH


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This is done with the NBAP message RADIO LINK SETUP REQUEST message, where following

parameters are set:

PO1: defines the power offset for the TFCI bits; it ranges between 0 and 6 dB with a 0.25

step size.

PO2: defines the power offset for the TPC bits; it ranges between 0 and 6 dB with a 0.25

step size.

PO3: defines the power offset for the pilot bits; it ranges between 0 and 6 dB with a 0.25

step size.

In the same message, the TFCS, DL DPCH slot format, multiplexing position, FDD TPC DL

step size increase, etc. are defined.

The FDD TPC DL step size is used for the DL inner loop power control.

Power offsets

TFCS

DL DPCH slot format

FDD DL TPC step

Power Offsets for the DPCH


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Node B RNC

DCH Data Frame

Iub

UE

Uu

PO1

NBAP: RADIO LINK SETUP REQUEST

TPC

bitsPilot bits

TFCI

bits(optional) Data 2 bitsData 1 bits

PO3PO2

size

...

P0x: 0..6 dB

step size: 0.25 dB

Inner loop power control is also often called (fast) closed loop power control.

It takes place between the UE and the Node B

DL Inner Loop Power Control


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It takes place between the UE and the Node B.

We talk about UL inner loop power control, when the Node B returns immediately after the reception of

a U E s s i g n a l a p o w e r c o n t r o l c o m m a n d t o t h e U

level (the details will be discussed later on in the course). DL inner loop power control control is more complex. When the UE receives the transmission of the

Node B, the UE returns immediately a transmission power control command to the Node B, telling the

N o d e B e i t h e r t o i n c r e a s e o r d e c r e a s e i t s o u t p

T h e N o d e B s t r a n s m i s s i o n p o w e r c a n b e c h a n g e d

the equipment. If other step sizes are supported or selected, depends on manufacturer or operator.

The transmission output power for a DPCH has to be balanced for the PICH, which adds to the power

step size.

There are 2 DL inner loop power control modes:

DPC_MODE = 0: Each timeslot, a unique TPC command is send UL.

DPC_MODE = 1: 3 consecutive timeslots, the same TPC command is transmitted.

One reason for the UE to request higher output power is the case that the QoS target is not met.

It requests the Node B to transmit with a higher output power, hoping to increase the quality

o f t h e c o n n e c t i o n d u e t o a n i n c r e a s e d S I R

But this also increases the interference level for other phones in the cell and neighbouring

cells.

The operator can decide, whether to set the parameter Limited Power Increase Used.

If used, the operator can limit the output power raise within a time period.

DL Inner Loop Power Control


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DPC_MODE = 0

unique TPC command

per TS

DPC_MODE = 1

same TPC over 3 TS,

then new command

two modescell

TPC

TPCest per

1 TS / 3 TS

DL Inner Loop PC: UTRAN behaviour

UE WCDMA BTS Receiving the TPC commands BS adjusts the DL

CC / C


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Measured SIR < SIR target --> TPC command is "1"

Measured SIR => SIR target --> TPC command is "0"

Compare measured SIR with SIR target

value received from DL outer loop PC

Measure received SIR on DL DPCCH

BS sets the power on DL DPCCH andDL DPDCH following way:

TPC command = "1" --> increase power by 1 dB

TPC command = "0" --> decrease power by 1 dB

DL DPCCH + DPDCHs

Send TPC command on UL DPCCH

Changed power on DL DPCCH + DPDCHs

DPCCH/DPDCH power

UTRAN shall estimate the transmitted TPC command

TPCest to be 0 or 1; it shall update the power every slot.

After estimating the k:th TPC command, UTRAN

shall adjust the current DL power P(k-1) [dB] to a

new power P(k) [dB]:

P(k) = P(k- 1) + PTPC(k)

where PTPC(k) is the k:th power adjustment due to the

inner loop power control

DownlinkInnerLoopPCStepSize

DownlinkInnerLoop

PCStepSize

RNC: 0.5..2; 0.5; 1 dB(Range, Steps; Default)

The P-CCPCH is the timing reference for all physical channels.

As can be seen in the figure on the right hand side, following timing relationships exist:

Timing Relationship between Physical Channels


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g g , g g p

The SCH, CPICH, P-CCPCH and DSCH have an identical timing.

S-CCPCHs can be transmitted with a timing offsetS-CCPCH,n. (n stands for the n

th S-CCPCH.)

The timing offset may be different for each S-CCPCH, but it is always a multiple of 256 chips,i.e.S-CCPCH,n = Tn * 256 chips, with Tn {0,..,149}.

We have already seen, that some S-CCPCHs transmit paging information.

The associated PICH frame endsPICH = 7680 chips before the associated S-CCPCH frame.

DPCHs are also transmitted with a timing offset, which may be different for different DPCHs.

The timing offsetDPCH,k is similar to the S-CCPCH a multiple of 256, i.e.

DPCH,k= T

k* 256 chips, with T

k {0,..,149}.

The timing of a DSCH, which is allociated with a DPCH, is explained later on in the course

documentation.

AICH access slots for the RACH and CPCH also require a time organisation.

As we have seen e.g. with the RACH, an access slot combines two timeslots.

How can the timing to the P-CCPCH be identified?

The P-CCPCH transmits the cell system frame number (SFN), which increases by one with

each radio frame.

The AICH access slot number 0 starts simultaneously with the P-CCPCH frame, whose SFN

modulo 2 is zero.

SFN mod 2 = 0 SFN mod 2 = 1

P-CCPCH

Timing Relationship between Physical Channels


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P-CCPCH

AICH accessslots 0 1 1282 1175 964 13103 14 0

SCH

nth S-CCPCH S-CCPCH,n

kth S-DPCH DPCH,k

0..38144

(step size 256)

0..38144

(step size 256)

A major problem arises, when the UE is connected to several cells simultaneously.

The active set cells must transmit the DL DPCH in a way that their arrival time is within a receive

Radio Interface Synchronisation


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window at the UE.

DLnom is the nominal receive time of a radio frame with a specific CFN at the UE.

T 0 = 4 T S l a t e r , t h e U E s t a r t s t o t r a n s mi t t h T 0 i s a l w a y s c a l c u l a t e d r e l a t i v e t o t h e U E t

Of course, due to multipath propagation and handover situations, the reception of the

beginning of a DL radio frame is often not exactly at To times before the UE starts to send.

When the UE is in a soft handover, and moving from one cell to another, the radio frames arriving from

one cell may arrive later and later, while the radio frames of another cell arrive earlier. I.e., the

reception from the two neighbouring cells drifts apart.

The picture on the right hand side is only valid, if the UE is in the macro-diversity state. In this case,

the parameter Tm is the time difference between the nominal DL received signal DLnom and the

appearance of the first P-CCPCH of the neighbouring cell.

The serving RNC determines the required offset between P-CCPCH of the neighbouring cell and the

DL DPCH.

This information is sent as Frame Offset and Chip Offset to the target Node B.

The target Node B can change the transmission of the DL DPCH only with a step size of 256

chips, in order to be synchronised to the SCH and P-CCPCH structure.

The S-RNC informs also the UE about the Frame Offset.

Tm =

timing differenceRelative timing

between DL DPCH

Radio Interface Synchronisation


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UEcell1

T0 =

1024chips

cell2= target

cell for HO

range: 0..38399

Res.: 1 chip

SRNC

(Frame Offset, Chip Offset)

and P-CCPCH

range: 0..38144

res.: 256 chips

Offset

between DL DPCH

and P-CCPCH

range: 0..38399

res.: 1 chip

(Frame Offset)(TM)




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Part VI: Dedicated Physical Channel - Downlink

Part VII: Dedicated Physical Channel - Uplink

The UL dedicated physical channel transmission, we identify two types of physical channels:

Dedicated Physical Control Channel (DPCCH),

S 2 6

Uplink Dedicated Physical Channels


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Which is always transmitted with SF 256.

Following fields are defined on the DPCCH:

pilot bits for channel estimation. Their number can be 3, 4, 5, 6, 7 or 8.

Transmitter Power Control (TPC), with either one or two bits

Transport Format Combination Indicator (TFCI), which is optional, and a

Feedback Indicator (FBI). Bits can be set for the closed loop mode transmit diversity

and site selection diversity transmission (SSDT)

6 different slot formats were specified for the DPCCH. Variations exist for the compressed

mode.

Dedicated Physical Data Channel (DPDCH),

Which is used for user data transfer.

Its SF ranges between 4 and 256.

7 different slot formats are defined, which are set by the higher layers.

The DPCCH and DPDCH are combined by I/Q code multiplexing with each multiframe.

Multicode usage is possible. If applied, additional DPDCH are added to the UL transmission, but no

additional DPCCHs! The maximum number of DPDCH is 6.

The transmission itself is organised in 10 ms radio frames, which are divided into 15 timeslots. Thetimeslot length is 2560 chips.

Superframe = 720 ms



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10 ms Frame

TPC

bitsPilot bits

TFCI bits(optional)

Data 1 bits

Radio Frame

0

Radio Frame

1

Radio Frame

2

Radio Frame

71

DPDCHSF = 256 - 4

DPCCHSF 256

FBI bits(optional)

7 different

slot formats



format for changed SF &changed puncturing

Feedback Indicator for

Closed loop mode transmit diversity, &

Site selection diversity transmission (SSDT)


DOWNLINK


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TPC

bitsPilot bits

TFCI bits(optional)

Data 1 bitsDPDCHSF = 256 - 4

DPCCHSF 256

FBI bits(optional)

7 different

slot formats



format for changed SF &changed puncturing

Feedback Indicator for

Closed loop mode transmit diversity, &

Site selection diversity transmission (SSDT)

TPC

bitsPilot bits

TFCI

bits(optional)

Data 2 bitsData 1 bits

DPDCHDPDCH DPCCH DPCCH

UPLINK

Discontinuous transmission (DTX) is supported for the DCH both UL and DL.

If DTX is applied in the DL as it is done with speech then 3000 bursts are generated in one

second (1500 times the pilot sequence 1500 times the TPC bits)

Discontinuous Transmission and Power Offsets


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second. (1500 times the pilot sequence, 1500 times the TPC bits)

This causes two problems:

Inter-frequency interference,

3g rpls ru20 02 the physical layer rel99 v2

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