Top Banner
W-CDMA for UMTS – Principles u Introduction u CDMA Background/ History u Code Division Multiple Access (CDMA) u Why CDMA ? u CDMA Principles / Spreading Codes u Multi-path Radio Channel and Rake Receiver u Problems to Solve u Macro Diversity and Soft Handover u Near-Far Problem and Power Control u UMTS General Requirements u FDD vs. TDD u Key Parameters u Spectrum Allocation
36

W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division...

Feb 06, 2018

Download

Documents

votruc
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

W-CDMA for UMTS – Principles

u Introductionu CDMA Background/ History

u Code Division Multiple Access (CDMA)u Why CDMA ?u CDMA Principles / Spreading Codesu Multi-path Radio Channel and Rake Receiver

u Problems to Solveu Macro Diversity and Soft Handoveru Near-Far Problem and Power Control

u UMTS General Requirementsu FDD vs. TDDu Key Parametersu Spectrum Allocation

Page 2: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 2Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

References

H. Holma, A. Toskala (Ed.), “WCDMA for UMTS”, 5th edition, Wiley, 2010.A.J. Viterbi, “CDMA, Principles of Spread Spectrum Communication”, Addison-

Wesley, 1995.R.L. Peterson, R.E. Ziemer, D.E. Borth, “Introduction to Spread Spectrum

Communications”, Prentice-Hall, 1995.T. Ojanperä, R. Prasad, “Wideband CDMA for Third Generation Mobile

Communication”, Artech House, 1998.R. Prasad, W. Mohr, W. Konhäuser, “Third Generation Mobile Communications

Systems”, Artech House, March 2000.

Page 3: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 3Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA History

Pioneer Era (Spread Spectrum)40s and 50s: Spread Spectrum technique for military anti-jam applications

1949: Claude Shannon and Robert Pierce develop basic ideas of CDMA

1970s: Several developments for military systems (e.g. GPS)

Narrow-band CDMA Era

1993: IS-95 standard (mainly driven by Qualcomm)

1992–1995: RACE project CODIT (UMTS Code Division Testbed, PKI, Ericsson, Telia, etc.)

Wide-band CDMA Era

1995–1999: ACTS project FRAMES: FMA Mode 1 (TD/CDMA), FMA Mode 2 (W-CDMA)

1995: cdma2000 1x/ 3x (USA)

1998: UMTS (Rel.-99): FDD and TDD mode

1999: Harmonization: W-CDMA, TD-CDMA and multi-carrier CDMA (chip rate: 3.84 Mchip/sec)

1999: Narrowband TDD mode (TD-SCDMA), chip rate: 1.28 Mchip/sec

High-Speed CDMA Era

since 2000: HSDPA (Rel.-5/ 2000), E-DCH (Rel.-6/ 2002), HSPA+ (Rel.-7/ 2005)

cdma2000 1x EV-DO/DV

Page 4: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 4Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Spread Spectrum Technology

Problem of radio transmission: frequency dependent fading can wipe out narrowband signals for duration of the interferenceSolution: spread the narrow band signal into a broad band signal using a specialcode

Þ protection against narrow band interference

Side effects:u coexistence of several signals without dynamic coordinationu tap-proof

Alternatives:u Direct Sequence (UMTS)u Frequency Hopping (slow FH: GSM, fast FH: Bluetooth)

detection atreceiver

interferencespreadsignal

signal (despreaded)

spreadinterference

f f

power power

Page 5: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 5Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Spreading and Frequency Selective Fading

FDMA: Relatively small bandwidth oneach channel

u Guard bands to avoid interferencebetween the users

u Channels maybe (temporary)unavailable due to channelselective fading

CDMA: relatively large bandwidth ofthe spread signal

u Frequency selective fading causesonly some reduction in the level ofthe received signal

u Users are separated by thespreading sequence

22

22

2

frequency

channelquality

1

spreadsignals

frequency

channelquality

1 23

4

5 6

small bandwidth guard band

Page 6: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 6Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA Multiple Access

CDMA (Code Division Multiple Access)u all terminals send on the same frequency probably at the same time and

can use the whole bandwidth of the transmission channelu each sender has a unique random number (spreading sequence), the

sender XORs the signal with this random numberu the receiver can “tune” into this signal if it knows the pseudo random

number, tuning is done via a correlation function

Advantages:u all terminals can use the same frequency, less planning neededu huge code space (e.g. 232) compared to frequency spaceu interference (e.g. white noise) is not codedu forward error correction and encryption can be easily integrated

Disadvantages:u higher complexity of a receiver (receiver cannot just listen into the medium

and start receiving if there is a signal)u all signals should have the same strength at a receiver (power control)

Page 7: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 7Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA Multiple Access (contd.)

Principle of CDMA Communication

Page 8: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 8Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

DSSS (Direct Sequence Spread Spectrum) I

XOR of the signal with pseudo-randomnumber (code sequence)

u Many chips per bit (e.g., 128)result in higher bandwidth of thesignal

Spreading factor SF: ratio betweenchip rate RC and data rate Rb

u RC = Rb · SFu tb = tC · SF

Processing Gainu GS = 10 · log10(SF)

user data

codesequence

resultingsignal

0 1

0 1 1 0 1 0 1 01 0 0 1 11

XOR

0 1 1 0 0 1 0 11 0 1 0 01

=

tb

tc

tb: bit durationtc: chip duration

(data rate)

(chip rate)

(chip rate)

Page 9: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 9Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

DSSS (Direct Sequence Spread Spectrum) II

Xuser data

codesequence

modulator

radiocarrier

spreadspectrumsignal

transmitsignal

transmitter

demodulator

receivedsignal

radiocarrier

X

codesequence

basebandsignal

receiver

integrator

products

decisiondata

sums

correlator

Page 10: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 10Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA Principle (Downlink)

Code 0

Code 1

Code 2

S

data 0

data 1

data 2

Code 0

Code 1

Code 2

data 0

data 1

data 2

sender (base station) receiver (terminal)

Transmission overair interface

Page 11: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 11Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA Principle (Uplink)

Code 0

Code 1

Code 2

S

data 0

data 1

data 2

Code 0

Code 1

Code 2

data 0

data 1

data 2

sender (terminal) receiver (base station)

transmission overair interface

Page 12: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 12Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

UMTS Spreading

u Constant chip-rate of 3.84 Mchip/s (FDD)u Variable data rates are realized by different spreading factors of the

orthogonal channelization codesu Higher data rates: less chips per bit (and vice-versa)

u Senders are separated by unique, quasi-orthogonal scrambling codesu Simple code management: each station can reuse the same orthogonal

channelization codesu No need for precise synchronization as the scrambling codes remain

quasi-orthogonal

data1 data2 data3

scramblingcode1

chan.code3

chan.code2

chan.code1

data4 data5

chan.code4

chan.code1

sender1 sender2

scramblingcode2

Page 13: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 13Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Functionality of Channelization and Scrambling Codes

Channelization Code Scrambling CodeUsage UL: Separation of physical data

(DPDCH) and control channels(DPCCH) from same terminalDL: Separation of DL connectionsto different users within one cell

UL: Separation of terminals

DL: Separation of sectors/cells

Length 4 – 256 chips (1.0 – 66.7 µs) UL+DL: 10ms = 38400 chips

Number of codes Number of codes under 1scrambling code = spreadingfactor (SF)

UL: several millionsDL: 256

Code Family Orthogonal Variable SpreadingFactor

Long 10 ms code: Gold code

Spreading Yes, increases transmissionbandwidth

No, does not affect transmissionbandwidth

Page 14: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 14Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

OVSF-Coding Tree

1

1,1

1,-1

1,1,1,1

1,1,-1,-1

X

X,X

X,-X 1,-1,1,-1

1,-1,-1,11,-1,-1,1,1,-1,-1,1

1,-1,-1,1,-1,1,1,-1

1,-1,1,-1,1,-1,1,-1

1,-1,1,-1,-1,1,-1,1

1,1,-1,-1,1,1,-1,-1

1,1,-1,-1,-1,-1,1,1

1,1,1,1,1,1,1,1

1,1,1,1,-1,-1,-1,-1

SF=1 SF=2 SF=4 SF=8

SF=n SF=2n

...

...

...

...

In UMTS, spreading factors (SF) from 4 – 512 (DL) / 4 – 256 (UL) are used:

4 x SF4, 8 x SF8 …………………… 256 x SF256, 512 x SF512

Page 15: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 15Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Downlink Dedicated Channel Symbol and Bit Rates

Spreadingfactor

Channelsymbol rate

(kbps)

Channel bitrate (kbps)

DPDCHchannel bitrate range

(kbps)

Maximum userdata rate with

1/2-rate coding(approx.)

512 7.5 15 3-6 1-3 kbps

256 15 30 12-24 6-12 kbps

...

16 240 480 432 215 kbps8 480 960 912 456 kbps

4 960 1920 1872 936 kbps

4, with 3parallelcodes

2880 5760 5616 2.3 Mbps

Page 16: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 16Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA in Theory

u Sender Au sends Ad = 1, code sequence Ac = 1010011 (assign: “0”= –1, “1”= +1)u sending signal As = Ad × Ac = (+1, –1, +1, –1, –1, +1, +1)

u Sender Bu sends Bd = 0, code sequence Bc = 0110101u sending signal Bs = Bd × Bc = (+1, –1, –1, +1, –1, +1, –1)

u Both signals superimpose in spaceu interference neglected (noise etc.)u As + Bs = (+2, –2, 0, 0, –2, +2, 0)

u Receiver wants to receive signal from sender Au apply sequence AC chipwise (inner product)

u Ar = (+2, –2, 0, 0, –2, +2, 0) · Ac = 2 + 2 + 0 + 0 + 2 + 2 + 0 = 8u result greater than 0, therefore, original bit was „1“

u receiving Bu Be = (+2, –2, 0, 0, –2, +2, 0) · Bc = –2 –2 + 0 + 0 – 2 – 2 + 0 = –8, i.e. „0“

u wrong sequence CC = 1100110u Cr = (+2, –2, 0, 0, –2, +2, 0) · Cc = 0, decision impossible

Page 17: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 17Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA on signal level I

data A

key A

signal A

data Å key

keysequence A

Real systems use much longer keys resulting in a larger distancebetween single code words in code space

1 0 1

10 0 1 0 0 1 0 0 0 1 0 1 1 0 0 1 101 1 0 1 1 1 0 0 0 1 0 0 0 1 1 0 0

Ad

Ak

As

Page 18: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 18Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA on signal level II

signal A

data B

key Bkey

sequence B

signal B

As + Bs

data Å key

1 0 0

00 0 1 1 0 1 0 1 0 0 0 0 1 0 1 1 111 1 0 0 1 1 0 1 0 0 0 0 1 0 1 1 1

Bd

Bk

Bs

As

10-1

Page 19: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 19Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA on signal level III

Ak

(As + Bs)* Ak

integratoroutput

comparatoroutput

As + Bs

data A

1 0 1

1 0 1 Ad

10-1

1

-1

10-1

Page 20: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 20Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

CDMA on signal level IV

integratoroutput

comparatoroutput

Bk

(As + Bs)* Bk

As + Bs

data B

1 0 0

1 0 0 Bd

10-11

-110-1

Page 21: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 21Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

comparatoroutput

CDMA on signal level V

wrongkey K

integratoroutput

(As + Bs)* K

As + Bs

(0) (0) ?

Assumptionsu orthogonality of keysu neglectance of noiseu no differences in signal level => precise power control

10-11

-1

10-1

Page 22: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 22Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Properties of Spreading Sequences

Cross correlation function (CCF)

Auto correlationfunction (ACF)

Code sequence #1

Code sequence #2

Required properties of spreading(properties of the transmitted signals):

• High ACF peak• Low ACF sidelobe ®

inter-symbol interference (ISI)• Low CCF ®

multi-user interference (MUI)

Page 23: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 23Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Multi-path Transmission

Multi-path components can be resolved due to ACF of codes

Spreader

SpreadingSequence c(t)

Despreader(Correlator)

SpreadingSequence c(t-Td)

Receiversynchronizes toeach multi-pathcomponent forde-spreading

Page 24: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 24Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

RAKE Receiver

Correlate and track each multi-path component separately

Optimal coherent combining

RAKE receiver with K fingers• trackers: independent tracking

of dominant paths• searchers: scan a time window to

search (the pilot channel) fordominant multi-path components

• time resolution in UMTS approx.200 ns

Page 25: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 25Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

RAKE Receiver – Practical Realization

Page 26: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 26Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Macro-Diversity & Soft Handover

Optimal coherent combiningin the RAKE receiver (at MS)

NodeB 1NodeB 2

UE

Page 27: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 27Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Multi-user CDMA

Conventional CDMA Receiver (Base Station):

• coherent (amplitude and phase) RFdemodulation at base station

• separate despreading and demodulation ofeach signal at base station

• one Rake receiver with K fingers per user• unsynchronized transmission between the

mobiles

Despreading(Correlator)

SpreadingSequence c1(t-Td1)

RAKE 1

SpreadingSequence c2(t-Td2)

RAKE 2

SpreadingSequence cn(t-Tdn)

RAKE n

Page 28: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 28Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Near-Far Problem:• Spreading sequences are not orthogonal

(multi-user interference)• Near mobile dominate• Signal to interference ratio is lower for far

mobiles and performance degrades

The problem can be resolved throughdynamic power control to equalize allreceived power levels

AND/OR

By means of joint multi-user detection

Near-Far Problem – Power Control

NodeB

UE 1

UE 2

Page 29: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 29Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Interference Cancellation

Multi-user Interference Cancellation (Joint Detection):

Detection mechanism takesinto account interferencefrom other users as all signalsare known in the receiver(known interference can becanceled)

Multi-userDetector

(JointDetection/

InterferenceCancellation)

Despreading(Correlator)

c1(t-Td1)

RAKE 1

c2(t-Td2)

RAKE 2

cn(t-Tdn)

RAKE n

Page 30: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 30Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Interference Cancellation – Realization

Subtractive interference cancellation

Page 31: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 31Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

FDD vs. TDD Mode

UMTS supports FDD and TDD

FDD mode:u Multiple access scheme: DS-CDMA (Direct Sequence-CDMA)u Symmetric capacity of up- and down-linku Better suited for low bit rate transmission in larger cells

(no timing advance, no synchronization from MS required)

TDD mode:u Multiple access scheme: TD-CDMA (JD-CDMA)u Asymmetric capacity allocation for up- and down-linku Strict synchronization required for MS (timing advance)u Relaxed power control and near-far resistance by the use of intra-cell

multi-user interference cancellation (spreading factor 1 - 16)

Page 32: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 32Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

FDD vs. TDD Mode (contd.)

TDD-Mode

FDD-Mode(one direction)

Page 33: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 33Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

TDD Mode Switching

1 Frame (10ms) of 15 Slots

multiple switching points, symmetric DL/UL allocation

multiple switching points, asymmetric DL/UL allocation

single switching point, symmetric DL/UL allocation

single switching point, asymmetric DL / UL allocation

Page 34: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 34Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

W-CDMA for UMTS – Summary of Key Parameters

Multiple-Access DS-CDMA (TD-CDMA)Duplex scheme FDD (TDD)

Chip rate 3.84 MChip/s(TDD: 1.28/ 3.84/ 7.68 MChip/s)

Carrier spacing Flexible in the range 4.6 – 5.0 MHz(200 kHz carrier raster)

Frequency bands 1920 – 1980 / 2110 – 2170 paired (FDD)1900 – 1920 and 2010 – 2025 unpaired (TDD)

Frame length 10 ms / (15 time slots)Inter-BSsynchronization

FDD mode: No accurate synchronization neededTDD mode: Synchronization needed

Multi-rate/Variable-rate scheme

Variable-spreading factor + Multi-codeSpreading factor: 4 – 256 (FDD) and 1 – 16 (TDD)

Channel codingscheme

Convolutional coding (rate 1/2 – 1/3)Turbo coding

Page 35: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 35Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

Global Spectrum Allocations for IMT-2000

ITU2010 20251980

MSS MSS*1930

IMT-2000 MSSMSS*IMT-2000

2160 2170 2200 MHz

*Region2

1885 2110

PHS

20101980 2025Japan

2110 22002170

IMT-2000 MSSMSSIMT-2000

18951885 1918.1 MHz

1980 2110 22002170

IMT-2000 MSS

19001880

DECT

2010

MSSIMT-2000

2025 MHz

Europe

2110 220021652150

Reserve MSSBroadcast Auxilary

1910 1930 1990 2025

MSS

1850

PCS*PCSA B CD E F

PCSA B CD E F

MHz

USA

20101980 2025

China2110 22002170

MSSMSS

1900 1920 MHz1865 1880 1945 1960

CDMA FDD-WLL

FDD-WLLCDMA

TDD-WLL

MSS: Mobile Satellite Services

Page 36: W-CDMA for UMTS – Principles - Startseite TU · PDF fileW-CDMA for UMTS – Principles u ... “WCDMA for UMTS”, 5th edition ... RACE project CODIT (UMTS Code Division Testbed,

UMTS Networks 36Andreas Mitschele-Thiel, Jens Mueckenheim Oct. 2012

UMTS Spectrum

2200M

Hz

2000M

Hz

2100M

Hz

1900M

Hz

Unpaired Band: 20 + 15MHz (1900-1920 and 2010-2025MHz) for TDD

Paired Band: 2 x 60MHz (1920-1980 and 2110-2170MHz) for FDD

Up-link Down-link

Satellite Band: 2 x 30MHz (1980-2010 and 2170-2200MHz)

1 2 3 11 12. . .

1920 MHz 1980 MHz

1 2 3 11 12. . .

2110 MHz 2170 MHz

5 MHz

Uplink Downlink

Details: