Channel Config RA

7/25/2019 Channel Config RA

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© Nokia Solutions and Networks 2014RA41213EN60GLA0

LTE Radio Parameters RL60

Channel Configuration and Random

Access



4 © Nokia Solutions and Networks 2014RA41213EN60GLA0

Module Objectives

After completing this module, the participant should be able to describe

discuss and analyze:

• UL and DL channels

• DL channel Configuration

• UL Channel Configuration and related Parameters

• Overall RA process• Contention-based and contention-free RA

• PRACH configuration options




Module Contents

• Overview

• DL Channels and Signals• UL Channels and Signals

• Random Access

• RA Procedure

• Preamble Generation




Overview - Channels

Upper Layers

RLC

MAC

PHY

Logical channels

Transport channels

B C C H

C C C H

P C C H

MT C H

M C C H

B C H

P C H

DL - S C H

RA C H

UL - S C H

P B C H

P D S C H

P HI C H

P D C C H

P C F I C H

P M C H

P U C C H

P RA C H

P U S C H

M C H

C C C H

D C C H

DT C H

ULDL

Air interface

D C C H

DT C H

S y n c h

R S

S R S

D R S




DL Physical Channels Allocation

- RS: Reference Signal

• Occupies at least 8 RE per RB(84 RE for normal CP )

throughout the whole system bandwidth

- PSS/SSS: Primary/Secondary Synchronization Signal

• Occupies the central 72 subcarriers across 2 symbols

• PBCH: Physical Broadcast Channel

• Occupies the central 72 subcarriers across 4 symbols

- PCFICH: Physical Control Format Indication Channel

• Occupies up to 16 RE per TTI

- PHICH: Physical HARQ Indication Channel

• Occupies 12 RE, and Tx during 1st symbol of each TTI or

alternative during symbols 1 to 3 of each TTI

- PDCCH: Physical Downlink Control Channel

• Occupies the REs not used by PCFICH and PHICH andReference Signals within the first 1, 2 or 3 symbols of each

TTI

- PDSCH: Physical Downlink Shared Channel

• Is allocated the RE not used by signals or other physical

channels

RB




UL Physical Channels and Reference Signals

• PUSCH: Physical Uplink Shared Channel

• Intended for user data (carries traffic for multiple UEs) and

control data

• If control data is to be sent when traffic data is being

transmitted, UE multiplexes both streams together

• PUCCH: Physical Uplink Control Channel

• Carries H-ARQ Ack/Nack indications, uplink scheduling

request, CQIs and MIMO feedback

• Only control information is sent. The UE uses Resources

Element at the edges of the channel

• PRACH: Physical Random Access Channel

• SIB2 indicates the resource elements for PRACH use

• System Information contains a list of allowed preambles (64

per cell) and the required length of the preamble.

• DRS: Demodulation Reference Signal

– For uplink demodulation and channel estimate

• SRS: Sounding Reference Signal

– For uplink channel aware scheduling

RACH

CCCH DCCH DTCH

UL-SCH

PRACH

PUSCH PUCCH

Logical

Transport

PHYS.

RLC

MAC




eNode B

CQI, PMI, RI,

ACK/NACK

SR

RNTI

DL scheduling

UL Grant

UL Power Control

n x per cell

DL control

configuration

1x per cell

HARQ Info

CQI, PMI, RI,

ACK/NACK

Overview – Control Information

CQI: Channel Quality Indicator

PMI: Precoding Matrix Indicator

RI: Rank Indicator

SR: Scheduling Request

ACK: Acknowledgement

NACK: Negative Acknowledgement

RNTI: Radio Network Temporary Indicator

HARQ: Hybrid Automatic Retransmission

reQuest




Generic - Bandwidth

- Channel bandwidth: Bandwidths ranging from 1.4 MHz to 20 MHz

- Data subcarriers: They vary with the bandwidth

• 72 for 1.4MHz to 1200 for 20MHz

FDD CarrierBandwidth

[MHz]

Number ofPRB

1.4 6

3 15

5 25

10 50

15 75

20 100

ulChBw / dlChBw

Defines the UL and DL bandwidth and the

number of available Physical Resource Blocks

LNCEL1.4 MHz (14), 3 MHz (30), 5 MHz (50),

10 MHz (100), 15 MHz (150), 20 MHz (200)

10 MHz(100)




Generic - Carrier Frequency and Bandwidth (FDD)

100 kHz

... ...

FUL = FUL_low + 0.1(NUL – NOffs-UL)

FDL = FDL_low + 0.1(NDL – NOffs-DL)

EARFCN

N UL : earfcnUL

N DL : earfcnDL

Bandwid th

UL: u lChBw

DL: d lChBw

*Noffs-DL & Noffs-UL specified by

TS 36.101 for each band

earfcnUL/ earfcnDL

Absolute Radio Frequency Channel Number

LNCEL; 0...65535; 1; -

earfcnUL = earfcnDL + 18000




EUTRA Channel Numbers

Examp le (band 12)

F UL = 708 MHz = 698 MHz + 0.1 (23100 – 23000) MHz

F DL = 738 MHz = 728 MHz + 0.1 (5100 – 5000) MHz




Generic - Physical Layer Cell Id

- As a result of cell search the UE should acquire:

• PHY cell ID

• 10ms and 5ms timing

• CP length

• Duplex mode (TDD/FDD)

• Physical Layer Cell Identity is used to differentiate neighbor cells

• It consists of the two parts; Physical layer Cell Identity Group and Physical layer Identity

• Physical Layer Cell Identity = 3 x Physical layer Cell Identity Group + Physical layer Identity• Decoded during synchronization using primary and secondary sync signal

Strongest Signal

Primary

Synchronization Signal

Secondary

Synchronization Signal

L1 id, slot (0/10)

Physical Layer

Cell ID, Frame

Alignment

Cell ID Group 0

(3 L1 id’s)

Group 167

Cell ID Group i

(3 L1 id’s) 168 Cell IDgroups

Phy L Cell ID

phyCellId:Physical Cell Id

LNCEL; 0..503; 1; -

(Range; Step; Default)




Generic - Time Structure (Frame Type 1)

19

144 Ts = 4.69 µs

160 Ts

CP Symbol C PSymbol C

PSymbol C PSymbol C

PSymbol C PSymbol C

PSymbol

CP Symbol

512 Ts = 16.7 µs

CP Symbol CP Symbol CP Symbol CP Symbol CP Symbol

CP Symbol

1024 Ts = 33.3 µs

CP Symbol CP Symbol

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0

Radio frame = 10 ms

subframe = 1 ms

Cyclic Prefix

x2047-Ncp, … x2047

OFDM Symbol (Time Domain Samples)

x0, x1, …, x2047

Symbol Tsym = 2048 Ts = 66.67 µsTcp = Ncp Ts

Df = 15 kHz, UL/DL - Extended Prefix

Df = 7.5 kHz, UL/DL - Extended Prefix

Df = 15 kHz, UL/DL - Normal Prefix

Slot = 15360 Ts = 500µs

7.5kHz Only used for MBMS




Generic – Time Structure and CP length

- Subframe length is 1 ms for all bandwidths

- Slot length is 0.5 ms

• 1 Subframe= 2 slots- Slot carries 7 symbols with normal cyclic prefix or 6 symbols with extended prefix

• CP length depends on the symbol position within the slot:

- Normal CP: symbol 0 in each slot has CP= 160 x Ts (5.21μs and remaining symbols

CP= 144 x Ts ( 4.7μs)

- Extended CP: CP length for all symbols in the slot is 512 x Ts ( 16.67µs)

Short cyclic prefix:

Long cyclic prefix:

Copy= Cyclic prefix

= Data

5.21 s

16.67 s

Ts: ‘sampling time’ of the overallchannel. Basic Time Unit.

Ts =1 sec

Subcarrier spacing X max FFT size

= 1 sec

15kHz X 2048

= 32.5nsec

Subcarrier spacing= 15kHz; max. FFT size= 2048




Module Contents

• Overview


• Random Access

• RA Procedure





DL - Channels and Signals Overview

Upper Layers

RLC

MAC

B C C H

C C C H

P C C H

MT C H

M C C H

B C H

P C H

DL - S C H

P B C

H

P D S C

H

P HI C

H

P D C

C H

P C F I C H

P M C

H

M C H

Air interface

D C C H

DT C H

S yn c

h

R S

PHY

HI

C F I

D C I




180 kHz

0.5 ms

Secondary Synchronization Signal (SSS)

Primary Synchronization Signal (PSS)

DTX

Slot id: 0 1 2 . . ..10.. ..19 0 1

Synch Signals – Time and Frequency




Incremental Time-Frequency Structure of Cell-specific Reference Signals

0l

0 R

0 R

0 R

0 R

6l 0l

0 R

0 R

0 R

0 R

6l

O n e a n t e n n a p

o r t

T w o a n t e n n a p o r

t s

Resource element (k,l )

Not used for transmission on this antenna port

Reference symbols on this antenna port

0l

0 R

0 R

0 R

0 R

6l 0l

0 R

0 R

0 R

0 R

6l 0l

1 R

1 R

1 R

1 R

6l 0l

1 R

1 R

1 R

1 R

6l

0l

0 R

0 R

0 R

0 R

6l 0l

0 R

0 R

0 R

0 R

6l 0l

1 R

1 R

1 R

1 R

6l 0l

1 R

1 R

1 R

1 R

6l

F o u r a n t e n n a p o r t s

0l 6l 0l

2 R

6l 0l 6l 0l 6l

2 R

2 R

2 R

3 R

3 R

3 R

3 R

even-numbered slots odd-numbered slots

Antenna port 0


Antenna port 1


Antenna port 2


Antenna port 3

Resource Element (RE) k, l

Not used for transmission on this antenna port (DTX)

Reference symbols (RS) on this antenna port

l=0 ……...... 6, 0 ……….. 6 l=0 ……...... 6, 0 ……….. 6

l=0 ……...... 6, 0 ……….. 6

Antenna port 0 Antenna port 1 Antenna port 2 Antenna port 3

F o u r a n t e n n a p o r t s

T w o a n t e n n a p o r t s

O n e a n t e n n a p o r t




Physical Broadcast Channel

- PBCH carriers essential system information like:

• DL BW configuration

• PHICH configuration• System Frame Number (8 MSB bits)

- PBCH enables blind detection of:

• DL antenna configuration {1TX, 2TX, 4TX} via CRC masking*

• 40 ms timing (2 LSB bits of SFN) via 40ms scrambling

* for decoding the CRC (Cyclic Redundancy Check) each MIB is masked with a codeword

representing the number of transmit antenna ports.




Physical Layer Downlink

DL-Physical Data & Control Channels

PBCH

Synchronization signals

Reserved for reference singals

Remark: PBCH does not use blocks reserved for reference signals

Code and rate-matching (repetition) to number of bits available on PBCH in 40 ms

One MIB (information bits + spare bits + CRC)

40 ms transmission time interval of PBCH

One radio frame

6 R B s

U s e d b a n d w i d t h

1 R B

One subframe (2 slots) 1 ms

Segmentation into four equal sized individually self-decodable units

PBCH




Physical Layer DownlinkDL-Physical Data & Control Channels

CFI CFI codeword <b0, b1, b2,……b31>

1 <0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1>

2 <1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0>

3 <1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,>

4 (reserved) <0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,>

PCFICH

• General

– Physical Control Format Indicator Channel (PCFICH) carries the CFI (Control Format Indicator)

▪ (Indicates the number of OFDM symbols used for transmission of control channel information ineach subframe)

– Carriers dedicated to MBSFN have no physical control channel and therefore no PCFICH

– 4 code words defined

▪ 3 CFIs used and one reserved for future use (see table below)

• Transmitted

– In the first OFDM symbol in a subframe

– The 32 bits of the CFI are mapped to 16 REs using QPSK modulation

– PCFICH is transmitted on the same antenna ports as the PBCH (1Tx, SFBC, SFBC-FSTD)

– Cell specific offset is added

– Cell specific scrambling




PHICH

- For HARQ ACK/NACK signaling the PHICH is

deployed.

- A PHICH is defined by its PHICH group number and an

orthogonal sequence number within the group.

- PHICH modulation is BPSK. Applying I/Q separation

and an SF=4 yields 8 orthogonal sequences for

normal CP. SF 2 is in use in case of extended CP,

hence there are 4 orthogonal sequences. I,e. in total

there may be 8 .. 224 PHICHs in one subframe.

- Example: BW=15 subcarriers normal CP, Ng=1/6, 1PHICH group. 12 symbols are to be transmitted.

- NRBDL : DL BW / RBs

- Ng = 1/6, 1/2, *1,* 2. setting: phichRes

prefixcyclicextendedfor82

prefixcyclicnormalfor8

DL

RBg

DL

RBggroup

PHICH

N N

N N N

+j -j -j +j7

+j +j -j -j6

+j -j +j -j5

+j +j +j +j4

+j -j+1 -1 -1 +13

+j +j+1 +1 -1 -12

+1 -1+1 -1 +1 -11

+1 +1+1 +1 +1 +10

Extended CPNormal CP

Orthogonal sequenceSequence

Index

+j -j -j +j7

+j +j -j -j6

+j -j +j -j5

+j +j +j +j4

+j -j+1 -1 -1 +13

+j +j+1 +1 -1 -12

+1 -1+1 -1 +1 -11

+1 +1+1 +1 +1 +10

Extended CPNormal CP

Orthogonal sequenceSequence

Index

Number of RBs

phichRes

#PHICH groups

LNCEL; 1/6; ½; 1; 2; 1/6

phichRes 1/6 1/2 1 2

#PHICH groups 3 7 13 25

# scheduled UE 24 56 104 200

e.g. 20 MHz

*Necessary with semi-persistent scheduling




PHICH Association and Resource Indication

- PHICH duration:

• 1 or 3 OFDM symbols in normal subframes (indicated via PBCH)

- PHICH linked to UL PRB

- Scattered grouping - spreads out the PHICH of adjacent PRBs to different PHICH

groups

- When DM-RS Cyclic Shift index is configured in UL grant, use DM-RS CS index asmodifier to adjust PHICH allocation

• Avoid PHICH collision e.g. in case of UL MU-MIMO

• Balance power among PHICH groups

- PHICH indexing:

• Both index of the group and within the group depend on first UL PRB index and

UL DM-RS Cyclic Shift

PhichDur

PHICH on symb. 1 / 1- 3

LNCEL; Normal (0), Extended (1); 1; Normal(0)

DM-RS CS: Demodulation Reference Signal Cyclic Shift




PDCCH Overview

- The PDCCH carries the UL & DL scheduling assignments

- A PDCCH is transmitted on an aggregation of one 1, 2, 4 or 8 control channel elements

(CCE). A CCE consists of 36 REs

- The aggregations of CCEs have a tree structure, where an aggregation consisting of n

CCEs starts on position (i mod n), where i is the CCE number

- Further restrictions on the aggregations are defined with a Hashing function

pdcchAggDefUEPDCCH LA UE default aggregation;

used, when enableAmcPdcch disabled

or no valid CQI exists

LNCEL; 1(0), 2 (1), 4 (2), 8 (3); -; 4 (2)

The target error probability for a missed detection of a PDCCH is 10-2




DL - L1/L2 control info: PDCCH Resources

- The Maximum Number Of OFDM Symbols For PDCCH parameter defines how many OFDM symbols can

be used.

- eNB selects the actual value for each TTI, which is signaled to UE in PCFICH.

- Range: 1, 2, 3 (BW > 1.4 MHz);

- Range: 2, 3, 4 (BW = 1.4 MHz)

- setting: maxNrSymPdcch

- Usage Based PDCCH Adaptation) allows to maximize PDSCH throughput and reduce PDCCH blocking

by adjusting dynamically the number of symbols used for PDCCH

- Example shows dynamic ( ActldPdcch) case for MaximumNumberOfOFDMSymbolsForPDCCH=3 (yellow)

maxNrSymPdcch

LNCEL; 1..3; 1; 3

ActldPdcch

LNCEL; false, true:false




Physical Layer Downlink Summary

DL-Physical Data & Control Channel

SSS

PSS

PBCH

PCFICH

PHICH

PDCCH

Reference signals

PDSCH UE1

PDSCH UE2

F r e q u e n c y

Time




Exercise: PDCCH Resources

Task:- Consider cell configuration: BW=50 PRB, 2 antenna ports, normal CP

- MaximumNumberOfOFDMSymbolsForPDCCH=2

- Ng = 1/6

Calculate the number of available PDCCHs.

Assume for frequency of occurancies of different aggregation levels (AL)

AL4 is 2 times the frequency of AL8 AL2 is 2 times the frequency of AL4

AL1 is 1/2 times the frequency of AL2




Solution: PDCCH Resources

Task:

- Consider cell configuration: BW=50 PRB, 2 antenna ports, normal CP

- MaximumNumberOfOFDMSymbolsForPDCCH=2

- Ng = 1/6

Calculate the max number of PDCCHs.

Solution:

- 1st symbol yields 2 REGs per PRB x 50 PRB = 100 REGs (because of the reference signals)

- 2nd yields 3 x 50 = 150 REGs. Total: 250 REGs. (no reference signals )

- 4 REGs for PCFICH, 2x3=6 for PHICH 240 REGs remain for PDCCH

- 240 div 9 = 26 CCEs are available

- For 1 distribution 1xAL8 + 2xAL4 + 4xAL2+2xAL1

- Aggregation level 8 1x = 8 CCEs- Aggregation level 4 2x = 8 CCEs

- Aggregation level 2 4x = 8 CCEs

- Aggregation level 1 2x = 2 CCEs

26 CCEs are consumed for 9 PDCCH.




Downlink carrier aggregation - 40 MHz

• A regular cell is paired with additional logical cell serving

the same site sector.

• LTE 1089 supports only inter-band carrier aggregation with

specific constraints with respect to bands that are allowed tobe paired.

• Only non-GBR data could be sent via secondary cell

• All cells handling CA (Carrier Aggregation) UEs serve

simultaneously also regular, non-CA UEs

• There is no carrier aggregation in the uplink direction

PRIMARYCELL

SECONDARY

CELL

CA capable UE

Carrier 1

Carrier 2





Cells to be paired for CA feature should belong to the same

sector:

• LCELL/sectorId is a new parameter introduced by

LTE1089

• For other than CA feature this information is

meaningless

• for the cells to be aggregated the same sectorId in LCELL

associated with the given LNCEL should be provided

• No more than 2 cells with the same sectorId could be

configured

LCELL

sectorId

LNBT

S

LNCEL

LCELLsectorId

CAREL

lcrId

LNCELSectorid Cell sector id

LNCEL; 0…255; -





• In the next step, logical cell that could be used

as a secondary one (from the primary cell point

of view) should be explicitly configured – inanother words, a relation between PCell and

SCell is created.

• This relation is realized via providing the lcrId

(matching with LNCEL/lcrId of the secondary

cell) in the new CAREL object under LNCEL of

the primary cell

• CAREL/lcrId should be unique within the site

LCELL

sectorI

d

LNBTS

LNCEL

LCELLsectorId

CAREL

lcrId

LNCELlcrId

PCell

SCell

LCRID Local cellresource ID of cell to

be aggregated

CAREL; 0…255; -





In case of Carrier Aggregation enabled still 420 users per given cell

could be active (like in non-CA case with 6 cells) however:

• At maximum 50 of them can

have secondary cell

configured (= added) and

• At maximum 50 others of

them can have this cell

configured as a secondary

one.

Cell

2

Cell

1

Max 420

Active UEs

C e l l s i n C a r r i e r a g g

r e g a t i o n

Max 50 CA PCell UEs

Max 50 CA PCell UEs

Max 50 CA

SCell UEs

Max 50 CA

SCell UEs

Cell 1 is SCell of Cell 2

Cell 2 is SCell of Cell 1

Max 420

Active UEs

Note:

This number could be

limited by

maxNumCaConfUeDc

parameter set in PCell

(by default equal to 20)

maxNumCaConfUeDc

Max number Carrier Aggr

configured UEs double carrier

LNBTS; 0…50; -20





There are two possible ways to activate the

secondary cell for the UEs for which

secondary cell was already added. The choice

depends on the setting of thesCellActivationMethod parameter:

•Blind (sCellActivationMethod = BLIND)

•Buffer based (sCellActivationMethod =

nonGBRBufferBased)

Period activation occassion

Configure UE with SCell

SCell configured, not

activated

Scell

activated

Start periodic

activation cycle

Compare nGBR buffer

against current

activation threshold

Scell activated

Restart

timer

Start

calculatingactivation

threshold

value

RRM signaling

nGBR buffer based

At sub frame n+8

Blind activation

sCellActivationMethod

SCell activation method

LNBTS :nonGBRBufferBased (0),blind (1); - nonGBRBufferBased

(0)




DL Carrier Aggregation

Buffer based activation of the secondary cell

means that every sCellActivationCyclePeriod it is

checked whether all non-GBR data awaiting initialtransmission in the buffer of that UE is greater than

the certain dynamically calculated threshold.

amount of data that could be

transmitted solely by the

primary cell based on the

throughput reached in the

past by this UE Period activation occasion

Configure UE with SCell

SCell configured, not

activated

Scell

activatedStart periodic

activation cycle

Compare nGBR buffer

against currentactivation threshold

Scell activated

Restart

timer

Start

calculatingactivation

threshold

value

RRM signaling

nGBR buffer based

At sub frame n+8

Blind activation

sCellActivationCyclePeriodSCell activation cycle period

LNBTS : 0.5s (0), 1s (1), 2s

(2), 4s (3), 8s (4), 16s (5) : 2




SCell activation:

buffered nGBR data

exceeds activaton

threshold

Simplified scenario is shown, with equal split of nGBR data between PCell and SCell

Time (individual TTIs)

n+8 TTI: start of

actual

transmission

over SCell

Not enough

buffered data to

use both PCell

and SCell

Sufficient amount of

data to use SCell

again

Not enough buffered

data to use both PCell

and SCell

SCell deactivation at the expiry

of sCellDeactivat ionTimerEnb

nGBR

data sent

over SCell

nGBR

data sent

over PCell

…….






• The division factor is limited to the range of 10…90% to avoid possible deadlock.

• If any of the serving cells succeeds in allocating all of its data share in current TTI (while

the other cell does not), this indicates that this cell has high scheduling potential.

Therefore in the next TTI it will be given additional 10% of the throughput share

0% 10% 90% 100%

PCell SCell

Division factor

The buffered non-GBR data is divided between PCell and SCell according to non-

GBR throughput share achieved in the past





• Additional cell bandwidth combinations are supported on top of RL50 band combinations:

BW1 BW2

5 MHz 5 MHz

5 MHz 10 MHz

10 MHz 10 MHz5 MHz 15 MHz

5 MHz 20 MHz

10 MHz 15 MHz

10 MHz 20 MHz

15 MHz 15 MHz15 MHz 20 MHz

20 MHz 20 MHz

All these new RL60 combinations are supported

by FSMF only

Supported already in RL50; FSME/FSMF

Supported already in RL50; FSME/FSMF

Supported already in RL50; FSMF





Support for additional band combinations are provided in RL60 on top of RL50:

Band A Band B

Band 1 2100 Band 5 850

Band 1 2100 Band 8 900

Band 3 1800 Band 5 850

Band 3 1800 Band 8 900

Band 5 850 Band 12 US 700

Band 1 2100 Band 18 800 Lower

Band 1 2100 Band 7 2600

Band 2 1900 PCS Band 4 AWS

Band 2 1900 PCS Band 5 850

Band 2 1900 PCS Band 17 700

Band A Band B

Band 3 1800 Band 3 1800

Band 3 1800 Band 7 2600

Band 3 1800 Band 20 800

Band 4 AWS Band 4 AWS

Band 4 AWS Band 17 700

Band 5 850 Band 7 2600

Band 7 2600 Band 20 800

Band 4 AWS Band 12 Lower 700

Band 3 1800 Band 28 700

Band 4 AWS Band 7 2600

Band 7 2600 Band 7 2600

All the RL60 combinations are supported by FSMF only

R L

5 0





• From RL60 onwards, intra-band combinations for CA are also supported.

• Two cases of intra-band allocation could be here distinguished:

• Distinction between contiguous and non-contiguous way of intra-band

allocation affects e.g.:

• Allowed allocation of center frequencies of the two involved carriers,

• Handling of UE capabilities,

• Requirements posed on the synchronization between carriers.

contiguous intra-band

allocation of CA

component carriers

non-contiguous intra-band

allocation of CA

component carriers




Module Contents

• Overview


• Random Access

• RA Procedure





UL Channel Mapping

Upper Layers

RLC

MAC

PHY

R A C H

C C C H

D C C H

D T C H

Air interface

P R A C H

P U S C H

U L - S C H

P U C C H

U C I

DR S

S R S




UE Channel state information (CSI) feedback types in LTE

- The purpose of CSI feedback is to provide the eNodeB

information about DL channel state to help in the

scheduling decision.

- Compared to the WCDMA/HSPA, the main new feature in thechannel feedback is the frequency selectivity of the report

- CSI is measured by the UE and signaled to the eNodeB

using PUCCH or PUSCH

- Channel state information in LTE can be divided into three

categories:

• CQI - Channel Quality Indicator• RI - Rank Indicator

• PMI - Precoding Matrix Indicator

- In general the CSI reported by the UE is just a

recommendation

• The eNodeB does not need to follow it

- The corresponding procedure for providing UL channel stateinformation is called Channel Sounding; it is done using the

Sounding Reference Symbols, SRS (not considered in this

presentation)

(1) eNodeBtransmission

(3) UEfeedback

(2) UE CSImeasurement




Channel Quality Indicator (CQI)

- The most important part of channel

feedback is the CQI

- The CQI is defined as a table containing 16

entries with modulation and coding

schemes (MCSs)

- The UE shall report back the highest CQI

index corresponding to the MCS for which

the transport block BLER shall not exceed10%

CQI index modulation

coding rate x1024

efficiency

0 out of range

1 QPSK 78 0.1523

2 QPSK 120 0.2344

3 QPSK 193 0.3770

4 QPSK 308 0.6016

5 QPSK 449 0.8770

6 QPSK 602 1.1758

7 16QAM 378 1.4766

8 16QAM 490 1.9141

9 16QAM 616 2.4063

10 64QAM 466 2.7305

11 64QAM 567 3.3223

12 64QAM 666 3.9023

13 64QAM 772 4.5234

14 64QAM 873 5.1152

15 64QAM 948 5.5547

UE reports highest MCS that it can

decode with a TB Error rate < 10%

taking into account UE’s receiver

characteristic

* Efficiency is defined as number of bits

per resource elements




Rank Indicator (RI)

- Rank Indicator is only relevant when the UE is operating in MIMO modes with spatialmultiplexing

• For single antenna operation or TX diversity it is not used

- RI is the UEs recommendation for the number of layers to be used in spatial

multiplexing

- The RI can have values {1 or 2} with 2-by-2 antenna configuration and {1, 2, 3, or 4}

with 4-by-by antenna configuration- The RI is always associated to one or more CQI reports

riEnable

Determines whether RI reporting isenabled (true) or not (false)

LNCEL; true (1); false(0); false (0)




Precoding Matrix Indicator (PMI)

- PMI provides information about the preferred Precoding Matrix

- Just like RI, also PMI is relevant to MIMO operation only

• MIMO operation with PMI feedback is called Closed Loo p MIMO

Example: codebook for 2 TX antennas




Precoding Matrix Indicator (PMI)

RL50: supports 4x2 closed loop MIMO




Periodic and Aperiodic Reporting

- The channel feedback reporting in LTE is divided into two main categories: Periodic and

Aperiodic

Periodic reporting

• The baseline mode for CQI/PMI/RItransmission is periodic reporting on

PUCCH

• If the UE is scheduled to send UL data inthe subframe where it should transmitperiodic CQI/PMI/RI, the periodic report ismoved to PUSCH and multiplexed with data

• The eNodeB configures the periodicity

parameters

• The size of a single report is limited up toabout 11 bits depending on the reportingmode

• Limited amount of frequency information

Aperiodic Reporting

• Aperiodic reports are explicitlytriggered by the eNodeB using a

specific bit in the PDCCH UL grant• Aperiodic report can be eitherpiggybacked with data or sent aloneon PUSCH

• Possibility for large and detailedreports (up to more than 64 bits)

The two modes can also be used to com plement

each other:

- The UE can be e.g. config ured to s end

Aper iodic repor ts only w hen i t is sch eduled,

whi le per iodic repor ts can provide co arse

channel informat ion on a regular basis

CQIAperEnable

enabling / disabling aperiodic CQI

/RI/PMI reporting on PUSCH.

LNCEL; false/true; true

cqiPerNp

CQI periodicityLNCEL; 2; 5; 10; 20; 20 ms

Categorization of CQI/PMI/rank reporting options




Categorization of CQI/PMI/rank reporting options

LTE CQI

reporting family

tree

Periodic

Frequency selective

Aperiodic

Single CQI Full FeedbackBest-M Average

No PMI

Mode 2-0

24 bits

No PMI

Mode 3-0

30 bits

Multi PMI

1-2

60 bits

Single PMI

Mode 3-1

64 bits

Multi-PMI

Mode 2-2

38 bits

Wideband

No PMI

Mode 2-0

6 bits

Single PMI

Mode 2-1

11 bits

No PMI

Mode 1-0

4 bits

Single PMI

Mode 1-1

11 bits

Single or Multi-PMI = closed loopMIMO with PMI feedback

No PMI = Single antenna, TxDiv orOL MIMO

The maximum number of feedback bitsfor each option Assuming 20 MHz BWand 4*4 CL MIMO is listed excluding RI

- With Periodic reporting RI is sent inseparate subframes with potentiallylarger periodicity

- In Aperiodic reporting The RI isseparately coded with each CQI/PMIreport

*See TS 36.213

cqiAperMode

Aperiodic CQI feedback mode

LNCEL; FBT1(0) – Family modes 2-x, FBT2(1)- Family modes 3-x

(x defined by MIMO algorithm internal in eNodeB); FBT2 (1)




CQI Aperiodic Reporting on PUSCH (2/2)

- Wideband feedback

• Only a single CQI value is fed back for the whole system band

• Cannot be utilized in FDPS

- Best-M average also called UE selected sub-band feedback

• For the M best sub-band an average CQI value is reported

- Full Feedback also called Higher Layer Configured sub-band feedback

• A separate CQI is reported for each sub-band using Delta compression

An example of Best-M

Average reporting with3 MHz BW (15 RBsmeans that the sub-band size is 2 RBsand the best 3 sub-bands are reported)

M = 3 best Subbands are selected and an average CQI value is reported

Channel SINR

Subband index 1 2 3 4 5 6 7 8

PRB index 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

BW /RB

Sub-bandsize

(RBs)

# bestSub-

bandsM

6-7 NA NA

8-10 2 1

11-26 2 3

27-63 3 5

64-110 4 6

CQI Periodic Reporting on PUCCH or PUSCH




CQI Periodic Reporting on PUCCH or PUSCH

- Wideband feedback or UE selected sub-band

- Period configurable

• 2, 5, 10, 20ms

- Wideband feedback similar to aperiodic reporting- UE selected sub-band:

• A single CQI result per report

• The total number of sub-bands is divided into J fractions called bandwidth

parts

• Only the best sub-band per BW part is reported• Example: for 3 MHz there are 4 RBs per sub-band so there are 15/4 = 4

sub-bands. Those 4 sub-bands are divided into 2 BW parts which means

that there are 2 sub-bands per BW part.*

- Configured by higher layer signaling

BW / RB SubbandSize k(RBs)

BW Parts (J)

6-7 NA NA

8-10 4 1

11-26 4 2

27-63 6 3

64-110 8 4

cqiPerNp

CQI periodicity

LNCEL; 2; 5; 10; 20; 20 ms

* A sub-band index is also signaled

The UE shall report a type 1 report per bandwidth part。

Type 1 report supports CQI feedback for the UE selected sub-bands

Type 2 report supports wideband CQI and PMI feedback.

Type 3 report supports RI feedback

Type 4 report supports wideband CQI

Uplink Control Signaling:




Uplink Control Signaling:

PUCCH vs. PUSCH

•PUCCH (Physical Uplink Control Channel)

• Used when the UE is not sending datasimultaneously

• Shared frequency and time resourcereserved exclusively for the UEstransmitting only L1/L2 control signals

• Optimized for large number ofsimultaneous UEs with relatively small

number of control signaling bits per UE(1…11)

• Very high multiplexing capacity, spectralefficiency e.g.

- 18 UEs/RB transmitting ACK/NACK(PUCCH Format 1a/1b)

- 6 UEs/RB transmitting 11-bit CQI + 2-

bit A/N (PUCCH Format 2b)

• PUSCH (Physical Uplink Shared Channel)

– Used when the UE transmits also data

– UE-specific resource that can be usedfor L1/L2 control signaling (based onscheduling decisions made by Node B)

– Capable to transmit control signals with

large range of supported control sizes(1… 64 bits)

– TDM between control and data(multiplexing is made prior DFT)

Single carr ier l imitat ion s :

Simultaneous transmission of PUCCH and PUSCH isnot allowed. Separate control resources for the caseswith and without UL data are required

*TDM = Time Domain Multiplexing

Zadoff-Chu sequences




Zadoff Chu sequences

- Zadoff-Chu sequences are used as

• UL demodulation and sounding reference signals

• random access preamble sequence

• DL primary synchronization signal- ZC sequences are CAZAC (constant amplitude zero autocorrelation) sequences

• Low cubic metric and flat frequency response

- The elements of ZC sequence are points from unit circle

- It is possible to create ZC sequences of any length with relatively simple formulas

- Depending on sequence length, different number of base/root sequences can be

formed• Sequence with prime number of elements is optimal

• Root sequence can be considered as circular. Different cyclic shifts of a rootsequence can be obtained by changing the starting element

- Cyclic shift must be larger than time ambiguity of received sequence

UL Reference Signal




U e e e ce S g a

Overview

Types of UL Reference Signals

- Demodulation Reference Signals (DM RS)

• PUSCH/PUCCH data estimation

- Sounding Reference Signals (SRS)

• Mainly UL channel estimation UL

DM RS is characterised by:- Sequence (Zadoff Chu codes)

- Sequence length: equal to the # of subcarriers used for PUSCH transmission

- Sequence group:

- 30 options

- Cell specific parameter

- Cyclic Shift: UE and cell specific parameter

UL DM RS allocation per slot for

Normal Cyclic Prefix

G f f




Group hopping for UL reference signal

• This feature randomises the sequence used to generate the:

• Demodulation Reference Signal for the PUCCH

• Demodulation Reference Signal for the PUSCH

• Sounding Reference Signal (SRS)

• Helps to improve performance when the ‘PCI mod 30’ rule was not followed

during the PCI planning process

• reduces risk of potential issues caused by cross-talk between neighboringcells

• UE are informed whether group hopping is enabled or disabled using SIB2

content

actUlGrpHop

Activation of uplink group hopping

LNCEL; 0 (False); 1 (True); 0 False

G h i f UL f i l





• Uplink Reference Signals are:

• Demodulation Reference Signal for PUCCH

• Demodulation Reference Signal for PUSCH

• Sounding Reference Signal (SRS)

PUCCH Formats

1, 1a, 1bPUCCH Form ats 2, 2a,

2bPUSCH SRS






Groups of Base Sequences

• All uplink Reference Signals are generated from the same set of base sequences

• There are 30 groups of base sequences

• Each group includes multiple sequences

• 1 sequence of

lengths 12, 24, 36,

48 and 60

• 2 sequences of

lengths 72, 84, 96, …

1200

Each group contains

G h i f UL f i l





Group Allocation

• The allocated group for a cell is not planned explicitly but is calculated from:

30mod)( sssgh f n f u

30modcellID

PUCCHss N f

30modssPUCCH

ssPUSCH

ss D f f

Group

PUCCH & SRS

PUSCH

PCI

Configurable Offset

(grpAssigPUSCH )

Psuedo random sequence initialized using

ROUNDDOWN [PCI / 30]

enabledishoppinggroupif 30mod2)8(

disabledishoppinggroupif 0)( 7

0 ssgh

i

iincn f

PUCCH, basics




,

• PUCCH (from single-UE perspective)

• Frequency resource of one RB

• Time resource of one sub-frame (A/N repetition is also supported)

- Slot based frequency hopping is always used

• It provides the sufficient degree of frequency diversity

• Hopping takes place on the band edges, symmetrically over the center frequency

- Multiplexing between UEs

• FDM btw RBs

• CDM inside the RB

slot

systembandwidth

Resource block

PUCCH* FDM = Frequency Division Multiplexing

CDM = Code Division Multiplexing

A/N = ACK/NACK

PUCCH UE Multiple Access Within a RB




PUCCH, UE Multiple Access Within a RB

• UEs are separated using of CDM (within an RB)

• Two orthogonal CDM techniques are applied on PUCCH

• CDM using cyclic shifts of CAZAC* sequence• CDM using block-wise spreading with the orthogonal cover sequence

- Multiplexing example: PUCCH Format 1/1a/1b (e.g., A/N)

• Both CDM techniques are in use -> 18 parallel resources

* The applied sequences are not true CAZAC but computersearched Zero-Autocorrelation (ZAC) sequences

RS RS RS

slot

SF=3

SF=4

Cyclic Orthogonal cover code

shift 0 1 2

0 0 12

1 6

2 1 13

3 7

4 2 14

5 8

6 3 15

7 98 4 16

9 10

10 5 17

11 11

block-wise spreading

CDM in

CS

domain

SF = 3 for Reference Signals and SF = 4 for ACK/NACKSF = Spreading Factor

deltaPucchShift

delta cyclic shift for PUCCH formats 1/1a/1b

LNCEL; 1..3; 1; 2 (i.e. 6 cyclic shifts)

*CDM = Code Division Multiplexing

PUCCH Formats




PUCCH Formats

• Format 1/1a/1b

• Length-12 CAZAC sequence modulation + block-wise spreading -> 1 symbol (1 or 2 bits per slot)

- Format 2/2a/2b

• Length-12 CAZAC sequence modulation (& no block-wise

spreading) -> 5 symbols per slot

PUCCH formats Control type

PUCCH Format 1 Scheduling request

PUCCH Format 1a 1-bit ACK/NACK

PUCCH Format 1b 2-bit ACK/NACK

PUCCH Format 2 CQI

PUCCH Format 2a CQI + 1-bit ACK/NACK

PUCCH Format 2b CQI + 2-bit ACK/NACK

Number of Bits Multiplexing Capacity (UE/RB)

ON/OFF keying 36, *18, 12

1 36, *18, 122 36, *18, 12

20 12, *6, 4

21

22

12,* 6, 4

12, *6, 4

*typical value

Mapping of logical PUCCH resources into physical PUCCH resources




Mapping of logical PUCCH resources into physical PUCCH resources

• Periodic CQI is located at the outermost RBs

• These resources are allocated explicitly via RRC• SR and persistent A/N are next to Periodic CQI

• These resources are allocated explicitly via RRC

• Dynamic A/N is located at the innermost PUCCH RBs

• Allocated implicitly based on PDCCH allocation

m=1 m=0

m=3 m=2

m=2 m=3

m=0 m=1

slot

system

bandwidthPUCCH

m = 0 & 1 may contain formats

2/2a or 2b (e.g. CQI) -> fixed

allocation

m = 2 & 3 may contain

formats 1/1a or 1b (e.g. ACK)

-> dynamic allocation

PUCCH Dimensioning (1/2)





- Scope: Dimensioning of the PUCCH region (how many RBs) to avoid excessive

overheads

- Necessary to calculate how many PUCCH resources (m) are needed for Formats1.x and

Formats 2.x






- Total number of Resources required for PUCCH is the sum of the resources required for

scheduling requests, for CQI and for Dynamic ACK/NACK:

MaxPucchResourceSize = nCqiRb + roundup {[((maxNumOfCce) + n1PucchAn –

pucchnanCS * 3 / deltaPucchShift ) * deltaPucchShift] / (3*12)} + roundup(pucchnanCS / 8)

nCqiRb

reserved RBs per slot for

PUCCH formats 2/2a/2b

LNCEL; 1..98; 1; 2

pucchnanCS

Number of cyclic shifts for

PUCCH formats 1/1a/1b

in the mixed region

LNCEL; 0..7; 1; 0

(0 means no use of mixedformats )

n1PucchAn

Offset to calculate ACK/NACK

resources from PDCCH CCE

LNCEL; 0..2047; 1; 36

maxNumOfCce depends on dlChBw parameter:

- if dlChBw is 5MHz then maxNumOfCce is 21




deltaPucchShift

delta cyclic shift for PUCCH

formats 1/1a/1b

LNCEL; 1..3; 1; 2

Flexible Uplink Bandwidth




p

• Achieved by increasing the bandwidth allocated toPUCCH, and not using the resources situated at

spectrum edge.

•LTE transmission bandwidth thus reduced, leaving

blanked areas at bandwidth edge.

•Blanked areas serve as a guard band for reducing

out of band emissions

Purpose of the feature is to define an area at the borders of uplink band

where PUSCH nor PUCCH are not allocated to any UE

0 1 2 3 4 5 6 7 8 9 1011 1213141516171819202122232425262728293031323334353637383940414243444546474849

Blankedarea

PUSCHresourcesPUCCHarea

Deployment possible with narrower spacing

WCDMA 5MHz LTE 5 MHz

blankedPucch

Blanked PUCCH resources):

LNCEL; 0..60; 1; 0

LTE786 modifies the receiver at the eNodeB. The blanked PUCCH PRBs are not received, therefore they do not influence the

received SINR. This means that the blanked resources do not contribute to the PUCCH RSSI nor SINR statistics, the

measurements of the PUSCH RSSI and SINR are performed on the reduced amount of PRBs

Example configuration (uplink bandwidth 10 MHz 50PRBs)




PUCCH Format 1.x

area

Example configuration (uplink bandwidth 10 MHz, 50PRBs)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

0 2 4 6 8 10 12 14 16 18 20 22 24 25 23 21 19 17 15 13 11 9 7 5 3 1

1 3 5 7 9

11 13 15 17 19 21 23 25 24 22 20 18 16 14 12 10 8 6 4 2 0

ulChBw = 10 MHz

0 1 2 3 4 5 6 7 8 9 1011 1213141516171819202122232425262728293031323334353637383940414243444546474849

0 2 4 6 8 9 7 5 3 1

1 3 5 7 9 8 6 4 2 0

nCqiRb = 20

blankedPucch =

16

Total PUSCH area: 40

PRBs

nCqiRb= 4

Total

PUCCH

area:

2x5PRB

No PUCCH blanking

PUCCH Format 2.x allocations

starting from PUCCH allocation

region 16 (PRB #8)

With PUCCH blanking

Actual blanked

area: 2x8PRB

Blanked

zone

Area

reserved

with nCqiRb

Frequency(PRBs)

Total PUSCH area: 24

PRBs

Total

PUCCH

area:

2x5PRB

PUSCH masking




PUSCH masking

The PUSCH blanking feature allows to overcome the regulatory limitations of

certain zones in the uplink

This allows the opertors to deploy LTE in wider system bandwidth, rather than in

two separate smaller systems• Obvious benefits in downlink capacity and especially peak throughputs (user

experience, marketing reasons)

• No need for inter-frequency measurements and handovers (measurement gaps!),

load balancing etc.

uplink downlink uplink downlink

5 MHz + 10 MHz 20 MHz + PUSCH blanking

Combined capacity:

100Mbps (32+68)

Capacity:

142Mbps

PUSCH masking




PUSCH masking

Each zone is determined by two parameters:

Length of the muted zone

First PRB that will be muted

ulsPuschMaskLength

LNCEL: Range: [1..100] (*)

Default: no

(*) actual values depend on ulChBw

These uplink resources

will never be allocated

11

PRBs

ulsPuschMaskStart

LNCEL : Range: [0..99] (*)

Default: no

(*) actual values depend on ulChBw

ulsPuschMaskStart =13

ulsPuschMaskLength = 11 11 PRBs muted: [#13 .. #23]

Sounding Reference Signal




UE specific channel state

information (CSI) is derived

from:

- PUSCH

- sounding reference signals

(SRS)

The SRS configurations provide

UEs by two SRS classes which are

introduced by feature:

SRS class …

that assigns a multitude of

resources for a limited number of

UE’s

that provides sufficient SRS

resources for the proper

scheduling of the UEs

UE scheduling & SRS Configuration

SRS Configuration




- The operator can choose an SRS configuration from a given set of predefined

configurations tailored for the usable PUSCH spectrum - srsConf igurat ion

- The SRS resources which are selected for the UEs are assigned by means of the RRC

Connection Reconfiguration and RRC Connection Reestablishment messages.

- The usage of measurements from SRS in closed loop uplink power control can be

enabled/disabled by setting the parameter Include SRS measurements In CL power

control (ulpcSrsEn ).

……

Wid b d SRS T i i N b d SRS T i i

SRS Bandwidths




Wideband SRS Transmission

(Non Frequency hopping SRS )

Sounding reference signal

1 6 R B s

Subframe 1 Subframe 6 Subframe 1 Subframe 2

Narrowband SRS Transmission

(Frequency hopping SRS )

Minimum Narrow

SRS bandwidth

= 4 RBs

More

wideband

SRS

bandwidth

= 4 RBs 3

= 12 RBs

SRS BW

config.

SRS

BW0

SRS

BW1

SRS

BW2

SRS

BW3

0 48 24 12 4

1 48 16 8 4

2 40 20 4 4

3 36 12 4 4

4 32 16 8 4

5 24 4 4 4

6 20 4 4 4

7 16 4 4 4

System bandwidths 40 –60 RBs.

Parameter SRSConfiguration defines the srs configuration.

Each option defines the values of a set of 3GPP parameters (Csrs, Bsrs) dedicated to SRS. See Tables 5.5.3.2-x in TS.36.211.

Module Contents




• Overview

• DL Channels and Signals

• UL Channels and Signals

• Random Access

• RA Procedure


Overview




Random access procedure is performed for the following events:

• Initial access from RRC_IDLE

• RRC Connection Re-establishment procedure

• Handover

• DL data arrival during RRC_CONNECTED requiring random access procedure

• UL data arrival during RRC_CONNECTED requiring random access procedure

• E.g. when UL synchronization status is "non-synchronized" or there are no

PUCCH resources for SR available

It takes two distinct forms:• Contention based (applicable to all five events);

• Non-contention based (applicable to only handover and DL data arrival)

Normal DL/UL transmission can take place after the random access procedure

In total there are 64 preambles per cell (pooled into 2 groups)

Preambles are grouped to indicate the length of the needed resource. A number of preambles are reserved for contention-free access

PRACH




PRACH channel structure for preamble format type 0

UE sends the preamble to the network on PRACH:

• PRACH occupies 6 resource blocks (of 180 kHz) ina subframe (or set of consecutive subframes)

reserved for sending random access preamble to

the network.

• The length of TCP (Cyclic Prefix) TPRE (Preamble)

and TGT (Guard Time) depends on the preamble

format

• PRACH reserved PRBs cannot be used by PUSCH

i.e. they are out of scope for scheduling for data

transmission

PRACH Types




PRACH types:

• Type 0: 1 ms duration

• Type 1: 2 ms

• Type 2: 2 ms

• Type 3: 3 ms

Format type 0 & type 1 supported

in RL60

PRACH Configuration




Type, time resources are defined by:

.

*3GPP TS 36.211 Table 5.7.1-2

prachConfIndex

LNCEL; 3..24;1; 3

Range is restricted to two different

ranges: 3-8 and 19-24 (internal)

PRACH configuration index:

PRACH




Where PRACH is placed in frequency domain:

• PRACH can be placed either on lower or upper edge of the

bandwidth• Therefore the possible range for prachFreqOffset is:

f r e q

tim

e

f r e q

tim

e

...

..

.

60UL

RB N n RA

PRBoffset

prachFreqOffset = roundup [maxPucchResourceSize /2]

If PRACH area is placed at the lower border of UL frequency

band then:

prachFreqOffset = MAXNRB – 6 - roundup

[maxPucchResourceSize /2]

If PRACH area is placed at the upper border of the UL frequency

band then:

The PRACH area (6 PRBs) should be next to PUCCH area either

at upper or lower border of frequency band to maximize the

PUSCH area but not overlap with PUCCH area

PUCCH

PRACH

Module Contents




• Overview



• Random Access

• RA Procedure


RA Procedure

- Random access procedure handled by MAC and PHY Layer through PRACH (in UL) and PDCCH (




y y g ( ) (

in DL)

- RACH only carries the preambles and occupies 6 resource blocks in a subframe

•Process:

- UEs selects randomly a preamble from the list of preambles broadcasted in the BCCH

- UE calculates OLPC parameters ( Initial Tx Power)

- Checks contention parameters (i.e. max. number of retries)

- UE transmits initial RACH and waits for a response before retry. Open loop PC ensures that each

retry will be at a higher power level.

- Upon receipt of successful UL RACH preamble, eNB calculates power adjustment and timing

advance parameters together with an UL capacity grant ( so UE can send more info )

DL

PUSCH: UE specific data

PRACH

response

ULPreamble

Not detected

Preamble

NextPRACHresource

On the resources indicated by PDCCH

RACH only carries the preambles ( no additional signaling or user data like in WCDMA Rel 99)

The eNodeB may also schedule data in the resource blocks reserved for random access channel preamble

transmission.



RA Procedure




UE eNB

RA Preamble assignment0

Random Access Preamble 1

Random Access Response2

The contention free random access procedure

• E.g. during handover a temporary valid preamble will be issued.

• It is (temporarily) dedicated to this UE.

• No contention resolution is needed as the preamble shall not be used by other UEs.

Module Contents




• Overview



• Random Access

• RA Procedure


Preamble generation




The random access preambles are generated from:

• Zadoff-Chu root sequences (838 in total) with zero correlation zone

• one or several sequences (length 839 each)Zadoff –Chu sequence is known as a CAZAC sequence (Constant Amplitude Zero

AutoCorrelation waveform).

There are 64 preambles sequences available in each cell. The set of 64 preamble

sequences in a cell is found by including first, in the order of increasing cyclic shift, all

the available cyclic shifts of a root Zadoff-Chu sequence

# root sequences = 838 in total

# preamble sequences = 64 per cell

Fig: Zadoff-Chu sequence. The real (upper)

and imaginary (lower) parts of the complex-

valued output (Wikipedia)

Fig:

example of

preambles

generation with

zero

autocorrelation

zone length equalto 279

(prachCS=14)

Preamble generation




Zero correlation zone and Cyclic shift

• zero correlation zone decode PRACH even if sent on the same time/ frequency

• preamble signals generated based on two different ZC sequences are not correlated within the geographical range

related to prachCS

• the dimensioning of the cyclic shift, must be greater than the maximum round-trip delay

Required number of different root Zadoff –Chu sequences grows with Ncs (Cyclic Shift) and the cell radius:

Limits due to premable formatsLimits due to preamble formatsLimits due to preamble formats

Preamble Generation




64 preambles made of Zadoff-Chu sequences with zero correlation zone:

• given by the logical index RACH_ROOT_SEQUENCE

• Zadoff Chu sequence u is given by

10, ZC

)1(

ZC

N nen x N

nun j

u

*3GPP TS 36.211 Table 5.7.2-4

rootSeqIndex

LNCEL;0…837;1; 0

• ZC sequence of length 839 (prime number) is used

• 838 different root sequences available. (PRACH Root

Sequence). Also different cyclic shifts can be useddepending on cell size

• Sub-carrier spacing is 1.25 kHz

)mod)(()( ZC, N C n xn x vuvu

Preamble Generation Root Zadoff-Chu sequence order

f bl f t 0 3




First: take all available cyclic shifts of one root

Zadoff-Chu sequence:

If not enough: take next logical index and so on

CS ZC CS CS

CS

RA RA RA RA RAstart shift shift CS shift group shift

0,1,..., 1, 0 for unrestricted sets

0 0 for unrestricted sets

( mod ) for restricted sets0,1,..., 1

v

vN v N N N

N C

d v n v n N v n n n

• Cyclic shift given by

for preamble formats 0 – 3.:

*3GPP TS 36.211 Table 5.7.2-2

prachCS

Preamble cyclic shift (Ncs configuration)

LNCEL;0…15;1; 0

prachHSFlag

Unrestricted or restricted (high speed) set selection

LNCEL; true, false; false

Preamble generation




-ExerciseCons ider a cell of 37 km radiu s.

Provid e a sensit iv e sett ing for th e cel l size dependent parameters

Support of high speed users




• If prachHsFlag = true the following rootSeqIndex values can be selecteddepending on prachCS (restricted set)

Cell range Required amount ofroot sequences

prachCS Possible range for rootSeqIndex

< 1.0 km 4 0 24...816

< 1.4 km 6 1 30…810

< 2.0 km 6 2 36…804

< 2.6 km 8 3 42…796

< 3.4 km 9 4 52…787

< 4.3 km 11 5 64…779

< 5.4 km 14 6 76…764

< 6.7 km 17 7 90…749

< 8.6 km 20 8 116…732

< 10.6 km 26 9 136…704

< 13.2 km 32 11 168…676

< 17.2 km 44 11 204…526

< 21.5 km 64 12 264…566

< 27.7 km 64 13 328…498

< 32.8 km 64 14 384…450

Preamble generation – High Speed Case




high-

speed set

no delay spread delay spread = 5,2 µs

With

preamble

guard

NCs

Configuration NCS

sign. per

root seq. #root seq. µs km µs km Guard NCS µs km µs km

0 15 18 4 14.3 2.15 9.1 1.37 2.25 12.75 12.2 1.82 7.0 1.04

1 18 15 6 17.2 2.57 12.0 1.79 2.25 15.75 15.0 2.25 9.8 1.47

2 22 12 6 21.0 3.15 15.8 2.37 2.25 19.75 18.8 2.82 13.6 2.04

3 26 10 8 24.8 3.72 19.6 2.94 2.25 23.75 22.6 3.40 17.4 2.62

4 32 8 9 30.5 4.58 25.3 3.80 2.25 29.75 28.4 4.26 23.2 3.48

5 38 7 11 36.2 5.44 31.0 4.66 2.25 35.75 34.1 5.11 28.9 4.33

6 46 6 14 43.9 6.58 38.7 5.80 2.25 43.75 41.7 6.26 36.5 5.48

7 55 4 17 52.4 7.87 47.2 7.09 2.25 52.75 50.3 7.54 45.1 6.76

8 68 4 20 64.8 9.73 59.6 8.95 2.25 65.75 62.7 9.40 57.5 8.62

9 82 3 26 78.2 11.73 73.0 10.95 2.25 79.75 76.0 11.41 70.8 10.6310 100 2 32 95.4 14.30 90.2 13.52 2.25 97.75 93.2 13.98 88.0 13.20

11 128 2 44 122.1 18.31 116.9 17.53 2.25 125.75 119.9 17.99 114.7 17.21

12 158 1 64 150.7 22.60 145.5 21.82 2.25 155.75 148.5 22.28 143.3 21.50

13 202 1 64 192.6 28.89 187.4 28.11 2.25 199.75 190.5 28.57 185.3 27.79

14 237 1 64 226.0 33.90 220.8 33.12 2.25 234.75 223.8 33.58 218.6 32.80

If prachHsFlag = true then hsScenario must be configured

hsScenario: defines highspeed scenario for a cell. Scenario 1 (open space scenario) and

scenario 3 (tunnel scenario). Scenarios are described in 36.141 Annex B.3

Preambles - Contention and Non-Contention




Non ContentionBased

ContentionBased

64 preambles

per cell

raNondedPreamb Total number of non dedicated RApreamblesLNCEL; 4 (0), 8 (1), 12 (2), 16 (3), 20(4), 24 (5), 28 (6), 32 (7), 36 (8), 40(9), 44 (10), 48 (11), 52 (12), 56 (13),

60 (14), 64 (15); 1 ; 40 (9)

Remaining are NonContention Based

Dedicated

preambles

Non-Dedicated

preambles

Type A and B Grouping of Preambles




The contention based Random Access preambles are grouped into:

• Type A - for requesting a normal UL resource.

• Type B - for requesting a larger resource due to Message Size AND Pathloss (PL)

criteria having been met.

raPreGrASizeRandom Access Preambles Group ASizeLNCEL; 4 (0), 8 (1), 12 (2), 16 (3), 20(4), 24 (5), 28 (6), 32 (7), 36 (8), 40(9), 44 (10), 48 (11), 52 (12), 56 (13),60 (14) ; 1 ; 32 (7)

raPreGrASize

raNondedPreambContention Based

64 preamblesper cell

raPreGrASizeType A Preambles

Type BPreambles

Remainingare Type B

raNondedPreamb ?

?

Type B Criteria




The Type B Random Access preambles are used if:

• The message size is greater than raSmallVolUl.

AND • the pathloss is less than:

PCMAX – preambleInitialReceivedTargetPower - deltaPreambleMsg3 - messagePowerOffsetGroupB

Where:

PCMAX is the UE maximum output power.

raSmallVolUlSmall Size Random Access DataVolume In Uplink

LNCEL; 56 bits (0), 144 bits (1), 208bits (2), 256 bits (3) ;1 ; 144 bits (1)

deltaPreMsg3

Delta Preamble Random AccessMessage 3LNCEL; -1...6 ;1 ; 0

raMsgPoffGrB RA Message Power Offset For Group B SelectionLNCEL; -infinity (0), 0 dB (1), 5 dB (2), 8 dB (3), 10 dB(4), 12 dB (5), 15 dB (6), 18 dB (7) ;1 ; 10 dB (4)

ulpcIniPrePwr

Preamble Initial Received TargetPowerLNCEL; -120 dBm (0), -118 dBm (1), -116 dBm (2), -114 dBm (3), -112 dBm(4), -110 dBm (5), -108 dBm (6), -106dBm (7), -104 dBm (8), -102 dBm (9),-100 dBm (10), -98 dBm (11), -96 dBm(12), -94 dBm (13), -92 dBm (14), -90dBm (15);1 ; -104 dBm (8)

LTE962 - RACH Optimization




• RACH Optimization feature deals with the

identification and resolution of conflicts and

inconsistencies due to incorrect configuration of

PRACH related parameters or PRACHparameters itself

• Differentiation of PRACH can be done in:

- Time Domain

• [prachConfIndex]

- Frequency Domain

• [prachFreqOff ]

- Code Domain• PRACH cyclic shift [prachCS]

• PRACH Root sequence [rootSeqIndex]

• RL50 gives possibility to configure PRACH related

parameters:

• as a part of eNB auto-configuration process

– for new deployments

• for existing sites by MANUAL triggeringoptimization process

Channel Config RA

Documents

Transcript of Channel Config RA