Saarbrücken, 06.07.2004 Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht...

Saarbrücken, 06.07.2004Standardisierung UMTS Dienste

FB E - Telekommunikationselektronik

H ochsc hule fürTechn ik und W irtscha ft

des S aa rlandesUn iversity of Ap plied Scie nces

Albrecht Kunz

Hochschule für Technik und Wirtschaft des Saarlandes

Saarbrücken, 04. Juli 2005

UMTS Air Interface Overview





All-IP Based Multimedia Terminals The Ultimate Goal

If I would have had a mobile multimedia terminal, I could:- look an the e-map where I am- send an email for some help- call my wife and kids and send them a picture of this beautiful location- get the latest news from the stockmarket while waiting.

It would be great

However I don‘t have a toollike that and I‘m lost.

I‘m in trouble





Keller

22.976Support of push service 23.974





Keller

22.976Support of push service 23.974

•3GPP Technical Specification Groups





Overview

• Motivation• UMTS key characteristics• CDMA Basics• Multipath reception / Rake receiver• TX/RX baseband processing• Transport & physical channels• Frame structure• Handover• Power control





UMTS Key Characteristics

multiple access scheme DS-CDMANominal carrier spacing 5MHzChip rate 3.84McpsFrame length 10msModulation DL: QPSK, UL: BPSK for I,Qmulti rate concept variable spreading, multi codeChannel coding Convolutional , turboFrequency reuse 1Inter BS synchronization no accurate synchronizationmulti-rate concept variable spreading, multi-codePacket access common and dedicated channelHandover concept Soft handover concept





Quality of Service (QoS) - End to End delay

«Hi ! How are you ?»«Hi ! How are you ?»

«Hi ! How are you ?»«Hi ! How...T

•small delays (10-20 ms) are not annoying for users

•delay < 200 to 400 ms, the effectiveness of the interaction is lower but can be still acceptable

•delay is > 400 ms, interactive voice communication is quite difficult



Digitaltechnik.ppt : 8



UMTS Terrestrial Radio Access (UTRA)

TDD mode FDD mode

Frequency Division Duplexbased on Alpha Concept

(DS-CDMA)

Time Division Duplex based on Delta Concept

(TD-CDMA)





Air Interface Characteristicstime

Frequency

time

Frequency

TDD modeTDD mode FDD modeFDD mode

En

erg

y, C

od

e

En

erg

y, C

od

e





UMTS frequency bands

1900 1950 2000 2050 2100 2150 2200

1 2 1 2'

1

2

2'

UMTS TDD (1900MHz-1920MHz,2010MHz-2025MHz)

UMTS uplink (FDD) (1920MHz-1980MHz)

UMTS downlink (FDD) (2110MHz-2170MHz)

[MHz]4 4

4 UMTS Satellite (1980MHz-2010MHz, 2170MHz-2010MHz)





Frequency reuse

R=7R=3 R=4R=1





Multiple Access

P

t

f

P

t

f

P

t

f

FDMA TDMA CDMA





Despreading

P

t

f

P

t

f





Multipath Propagation Environment

Propagation Environment

h(t,)

Channel Impulse response





Channel model

x x x x

1/W 1/W 1/W 1/W

cL(t)c3(t)

s(t)

c1(t) c2(t)

. . .

. . .

. . .

r(t): receive signal

s(t): transmit signal ck(t): time variant channel coefficients

L: number of channel coefficientsW: bandwidth of transmit signal s(t)1/W: time resolution of channel

r t c t s tk

Wkk

L

( )

1





Rake receiver

x x x x

1/W 1/W 1/W 1/W

cL*c3

*

q*(t)

c1* c2

*

. . .

. . .

xx x x x. . .

. . .

summer and integrator

r(t)r(t)

Um





UMTS – Prinzip der Bandspreiztechnik

Verwendung orthogonaler Spreizcodes, um die Nutzer in der Zelle zu separieren

SF = 1 SF = 2 SF = 4

c1,1 = (1)

c2,1 = (1,1)

c2,2 = (1,-1)

c4,1 = (1,1,1,1)

c4,2 = (1,1,-1,-1)

c4,3 = (1,-1,1,-1)

c8,8

c8,7

c4,4 = (1,-1,-1,1)

SF = 8





• Verwendete Modulationsart ist QPSK (downlink, d.h. Kommunikation von der Basisstation zur Mobilstation

• Codes unterschiedlicher Spreizfaktoren (Spreading Factor, SF) können verwendet werden

• Die okkupierte Bandbreite ist nach dem Spreizen SF-mal so groß

• Die spektrale Leistungsdichte wird durch den Spreizvorgang auf 1/SF reduziert

Verwendung orthogonaler Spreizcodes:

Spreizvorgang





• Anwendung eines Korrelators oder Matched Filters:

• Korrelator: Integration von SF Chips, bei Verwendung des richtigen Codes (phasensynchron zum Sender) tritt Korrelationsspitze auf

• Matched filter mit Entspreizsequenz (-t): Korrelationsspitze tritt auf bei vollständiger Überlappung von gesendeter Spreizsequenz und multiplizierter Entspreizsequenz

• Gleichheit der Sequenzen => +1*+1=1 und –1*-1=1

maximales Integrationsergebnis (Korrelationsspitze) !

• Unterschiedliche Codes führen zu Nebenzipfeln, da die Codes nicht vollständig orthogonal sind (Bsp: siehe Gold-Codes)

Entspreizvorgang: Entspreizen durch Multiplikation mit der gleichen Spreizfunktion, mit der gesendet wurde






Maximal LFSR Sequences = M-Sequences There are LFSRs with L memory elements and characteristic polynomial Q(x) that produce sequences with maximum period of length 2L-1. The sequences are called maximal LFSR sequences or m-sequences.The characteristic polynomials are called primitive polynomials.Tables of primitive polynomials exist (e.g. in Peterson/Weldon,Error Correcting Codes,1972).

Example: Degree 8 Q(x): 561 octal Q x x x x x( ) 8 6 5 4 1






Correlation Properties of M-Sequences

The out of phase values of the PACF of m-sequences (after mapping to a bipolar sequence) are all -1:

0 2 4 6 8 10 12 14 16-1.5

-1

-0.5

0

0.5

1

1.5m-sequence

0 2 4 6 8 10 12 14 16

0

5

10

15

even periodic autocorrelation function of m-sequence

Example:m-sequenceof length 15






Decimation of M-Sequences

Definition (decimation):

Given a m-sequence bn, generate a new sequence cn by taking every q-th element form bn.Then cn is said to be a decimation by q of bn.If bn is generated by ma(x) with roots ai then cn is generated by ma

q(x) with roots aiq.

If gcd(q, N) = 1 then cn is also a m-sequence.Example: N = 31 is prime therefore all decimations give m-sequences (some of which may be identical !!)






Crosscorrelation Properties of Gold-Sequences

If L is not 0 mod 4 then

pairs of m-sequences exist with three-valued crosscorrelation functions (CCF)

these three values are: -1, -t(L), t(L)-2

t L L( ) ( )/ 1 2 2 2

its called preferred pair !






Construction of Gold Codes

A set of Gold codes of length N is generated based on a preferred pair of m-sequences of the same length. The second m-sequence is generated from the first by decimation with the factor t(L). The set size is N+2 = 2L+1. N different sequences in the set are generated by the binaryaddition of sequence 1 with all cyclic shifts of sequence 2.The original sequences are added to the set giving a set sizeof N+2.

initial value determines output sequence

LFSR form-sequence 2

LFSR form-sequence 1

Gold code






Correlation properties of Gold Codes

Gold codes have three valued out of phase periodic autocorrelationfunction and even periodic crosscorrelation function:

g1(x) = x5 + x2 + 1 and g2(x) = x5 + x4 + x2 + x + 1 Example: Gold Codes of length N=31, L = 5, with Generator polynomials

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 1

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 2

0 10 20 30-10

0

10

20

30

PACF sequence 1

0 10 20 30-10

0

10

20

30

PACF sequence 2

0 10 20 30-10

0

10

20

30

PCCF sequences 1 and 2

The three out of phase correlationvalues are -1, -9 and 7






Gold Codes of Length 218-1 Segments of length 38460 of Gold codes of length 218-1 are usedin the WCDMA system (DL DPDCH/DPCCH).

Example: Generator polynomials:

g1(x) = x18 + x5 + x2 + x + 1 = m1(x)

g2(x) = x18 + x17 + x13 + x12 + x9 + x8 + x6 + x + 1 = m1025(x)

The second sequence is generated by decimating the first sequence with factor 2 (L+2)/2+1 = 1025.






Orthogonal Gold-Codes

For many Gold-Codes or Gold like codes of length 2L -1 the crosscorrelation value at phase 0 is -1. If these codes are suitably extended by one chip the crosscorrelation value at phase 0 is 0. Therefore the codes are orthogonal !!

g1(x) = x8 + x6 + x5 + x3 + 1 and g2(x) = x8 + x4 + x3 + x2 + 1

Original codes have length 255. Orthogonal codes havelength 256 by addition of the chip -1.

Out of phase correlation properties change due to the extension bit.

Example: L = 8






Correlation Properties of Gold like Codes of length 255

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 1

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 2

0 100 200 300-100

0

100

200

300PACF code 1

0 100 200 300-100

0

100

200

300PACF code 2

0 100 200 300-50

0

50

100PCCF code 1 and 2

0 10 20 30-20

-10

0

10

20Ausschnitt PCCF code 1 and 2

-1






Correlation Properties of Orthogonal Gold-Codes of Length 256

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 1

0 10 20 30-1.5

-1

-0.5

0

0.5

1

1.5Gold code 2

0 100 200 300-100

0

100

200

300PACF code 1

0 100 200 300-100

0

100

200

300PACF code 2

0 100 200 300-40

-20

0

20

40PCCF code 1 and 2

0 5 10-20

-10

0

10

20Auschnitt PCCF code 1 and 2

=0 --> orthogonal !





Downlink scrambling code generator

In

Qn

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

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

X

Y






spreading /modulation for downlink DPCH

-chiprate 3.84 Mcps - pulse-shaping Root-Raised Cosine (RRC) with a=0.22- QPSK modulation

p(t)

IQMuxDPDCH/DPCCH

cos(t)

p(t)

sin(t)cch cscramb

16*2K kbps 3.84 Mcps





spreading /modulation for uplink DPCH

DPDCH

cD

I

DPCCH

cC

Q j

I+jQ

cscramb

cos(t)

sin(t)

p(t)

p(t)

Real

Imag

Channelizationcodes (OVSF)

-chiprate 3.84 Mcps - pulse-shaping Root-Raised Cosine (RRC) with a=0.22- Dual BPSK modulation

*G

Anpassungsfaktor





RRC Impulse Response

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 10 20 30 40 50 60 70 80





Transport / Logical Channels

Physical Channels

BCH

FACH

PCH

RACH

CPCH

DCH

DSCH

Common Pilot Channel

Primary Common Control Physical Channel

Secondary Common Control Physical Channel

Physical Random Access Channel

Physical Common Packet Channel

Dedicated Physical Data Channel

Dedicated Physical Control Channel

Synchronization Channel

Physical Downlink Shared Channel

Page Indication Channel

Acquisition Indication Channel

Mapping of Transport Channels





Structure of Uplink Dedicated Channels

slot #0 slot #1 slot #i slot #14

frame #0 frame #1 frame #i frame #71

Tf=10 ms

Tsuper=720 ms

DPDCHData1

Ndata bits

DPCCHPilot

NTFCI bitsTFCI

NTFCI bits

Ts=2560 chips, 10*2k bits, k=0..7

FBINFBI bits

TPCNTPC bits





Structure of Downlink Dedicated Channels



Tf=10 ms

Tsuper=720 ms

PilotNpilotbits

TFCINTFCI bits

TPCNTPC bits

Data1Ndata bits

Data2Ndata bits

Ts=2560 chips, 10*2kbits, k=0..7

DPCCH DPDCH DPDCH DPCCHDPCCH





Multicode Downlink Transmission

PilotTFCI TPC

DPCH1Data1 Data2

Transmission Power

DPCH2Data1 Data2

DPCHnData1 Data2





Multicode Uplink Transmission

DPCCH Pilot TFCI FBI TPC

DPDCH1Data

DPDCHnData

DPDCH2Data





coding and multiplexing of Transport Channels (TC)

Transport-channelmultiplexing

Channel coding +optional TC multiplex

Static rate matching

Inner interleaving(inter-frame)

Dynamic rate matching(uplink only)

Inner interleaving(intra-frame)

Coding +interleaving

Ratematching

Interleaving(optional)

Multiplex

TC

Coding +interleaving

Ratematching

Interleaving(optional)

Ratematching

Interleaving

TC TCTC

The output after inner (intra-frame ) interleaving is typically mapped to one DPDCH.

Only for highest bit rates the output is mapped to several DPDCHs (multi-code transmission)





(a) Coding rate =1/2 constraint length=9

(b) Coding rate =1/3 constraint length=9

D

D

D

D

D

D

D

D

D

D

D

D

D

D

D

D

+

+

+

+

input

input

output 0G0=557 OCT

add MOD.2

output 1G1=753 OCT

output 1G1=663 OCT

+ output 2G2=711 OCT

output 0G0=561 OCT

Convolutional coder





Random Access Transmission

10 ms, 38400 chips

Message

P1

Pj

P0

Preamble

4096 chips





RACH Message Part



TRACH=10 ms

Data

ControlPilot

NTFCI bitsTFCI

NTFCI bits

DataNdata bits





Acquisition Indication Channel

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

2*Tf=20 ms

4096 chips 1024 chips

AI empty





Timing relationrelationship between preambles, AICH message

One access slot

p-a

p-m

p-p

Pre-amble

Pre-amble Message part

Acq.Ind.AICH access

slots RX at UE

PRACH accessslots TX at UE





Common Pilot Channel

Pre-defined symbol sequenceNTFCI bits




Tf=10 ms

Tsuper=720 ms





Primary Common Pilot Channel

• Characteristics of the primary common pilot channel

– The same channelization code is always used

– Scrambled by the primary scrambling code

– One per cell

– Broadcast over entire cell

• The primary common pilot channel is the phase reference for SCH, P-CCPCH, AICH, PICH and the default phase reference for all other downlink physical channels.





Secondary Common Pilot Channels

• Characteristics of the secondary common pilot channel

– usage of an arbitrary channelization code of SF=256

– scrambled by either the primary or secondary scrambling code

– zero, one or several per cell

– may be transmitted over only a part of the cell

• A secondary common pilot channel may be the phase reference for the secondary CCPCH and the downlink DPCH





Synchronization Channel

acp

acsi,0

Slot #0

256 chips

2560 chips

acp

acsi,1

Slot #1

acp

acsi,14

Slot #14

1 frame, 10 ms, 38400 chips

Primary SCH

Secondary SCH





Physical Downlink Shared Channel



Tf=10 ms

Tsuper=720 ms

DataNdata bits






Power control (1)

Outer loop (closed loop)

- adjust SIR target for inner loop

Inner loop (closed loop)

- SIR controlled

- user oriented

- for fast Power Control

Open loop for RACH





Power control (2)

MatchedFilter

RAKE Combiner

ViterbiDecoder

Frame ErrorDetector

LPF(Forget Factor )

TargetFER

T frm

SIRMeasurment

TPCCommand

Outer Loop

InnerLoop 0

SIR

TPCTarget SIR

Delay

0.1





Power control - inner loop adjust TX power of BS and MS to reduce near-far effect

Example (DL):

• MS estimates received power SRX of DPCCH after Rake combining

• MS estimates downlink interference IDL

• SIRest = SRX / IDL

• generate transmit power control (TPC) command according to SIRest > SIRtarget,DL ----> TPC = down SIRest < SIRtarget,DL ----> TPC = up

• BS increases power by DTPC dBs





Power control - TPC generation• BS: all base stations in the active set send TPC commands

based on a quality measurement

• BS: threshold for TPC is controlled in the outer loop by the network node

• MS: power up if TPC bits received of all BS indicate an upward step

• MS: power down if TPC bits received of at least one BS indicate downward step





Power control - open loop (1)

Control RACH TX power

uses– pathloss– SIR target broadcast by BCCH– Uplink interference level broadcast by BCCH– transmit power of CCPCH





Handover conceptSNR estimation[dB]

Time

Active set hysteresis threshold

Replace Bwith C

Remove A

A

A connected

Active set replace hyteresis

Replace Cwith B

B

C

Add B to active set





randomdata source

FEC + rate matching+ interleaving

OVS longscrambling

samplingrate

expansionRRC-filter nonlinear

PAPilot

TPC

TFCI

MUX

channel RRC-filter

searcher

Rake de-interleaving+ FEC decoding

TFCIdetection

Pilotdetection

TPCdetection

DEMUX

AWGN

Goldcodes 64 groups a 8 codes

Length = 38640

QPSK symbolscaling

PC

DAC

samplingrate

decimation

1 2

3

4

5

6

7 8 9 10 11 12 13 15

1617 21 23 24 27

22

26

29

30

31

BERcalculation

28

analogTx-filter

14

optional

nonlinearPA ADC

2018

analogRx-filter

19

optional

25

P/S

TPCevaluation

32

SIR Target

Saarbrücken, 06.07.2004 Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht...

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Transcript of Saarbrücken, 06.07.2004 Standardisierung UMTS Dienste FB E - Telekommunikationselektronik Albrecht...