Simulation and Analysis of 3G Air interface Wideband Coded Division Multiple Access working in...

Simulation and Analysis of 3G Air interface Wideband Coded Division Multiple Access working

in Downlink FDD

Electronics and Communication Department,Institute of Technology,Nirma University,Ahmedabad-382481.

4th August, 2012

As Part of Pedagogy Activity in EC Department, 2011, 2012

Presented By:Prof. Amit [email protected]

Meaning

Knowledge, the Object of knowledge, and the knower are the three factors that motivate the action; the senses, the work, and the doer are the three constituents of action

--The Bhagavad Gita(18.18)

ज्ञा�नं� ज्ञा�यं� परिज्ञा�ता� त्रि�त्रि धा� कर्म� च यंत्तु� दनं� ।कणं� कर्म� कता�त्रिता त्रि�त्रि धा� कर्म�सं�ग्रहः� ॥१८- १८॥

Presentation OutlineThe ObjectiveStandardization BodyMotivation to work WCDMA ParametersCDMA Transmitter and Receiver: A General ApproachAir Interface ArchitectureWCDMA ChannelsWCDMA Transmitter

The Objective of the Lecture

How the Technology has evolved.

Various Air Interfaces of 3G

Physical Layer of WCDMA Working In Downlink FDD

First Mobile Radio Telephone

Today’s Mobile

Source:www.gsmarena.com

Migration to 3G

Migration to 3G

Source: univ.zte.com/cn

3GPP- A Global Initiative

3GPP - Third Generation Partnership ProjectARIB - Association of Radio Industries and BusinessesCWTS - China Wireless Telecommunication Standard groupETSI - European Telecommunications Standards InstituteT1 - Standards Committee T1 TelecommunicationsTTA - Telecommunications Technology AssociationTTC - Telecommunication Technology CommitteeIETF - Internet Engineering Task ForceITU-R - International Telecommunication Union -RadiocommunicationITU-T - International Telecommunication Union - Telecommunication Standardization

Source: univ.zte.com/cn

IMT-2000 Vision Includes

Source: www.itu-t.com

UMTS General Architecture

Figure : General Architecture

Mobile Equipment : Radio Transmission & contains applications.

Mobile Termination, Terminal Equipment

USIM : Data and Procedures which unambiguously and securely identify itself in Smart Card.

User Equipment:

3GPP Rel.6 ObjectivesMigration from GSM based Network to

3G standard WCDMAScope and definition in progressIP Multimedia Services, phase 2„IMS messaging and group managementWireless LAN interworkingSpeech enabled services

„ Distributed speech recognition (DSR)Number portabilityOther enhancements

3GPP2 Defines3rd Generation Partnership Project “Two” �Separate organization, as 3GPP closely

tied to GSM and UMTS �Goal of ultimate merger (3GPP + 3GPP2)

remains

Various Air interfaces of 3G

3G

standards TD-SCDMA

CDMA2000

WCDMA

CDMA is the main technology of 3G

CDMA 2000

UWC

Architecture of channel Adaptive Hybrid ARQ/FEC

( ) ( )( ) ( )

2

opt

opt

R n rttn R n rttnR n R n rttn

CDMA Vs. WCDMA

Concepts We have to knowSimplex Vs. DuplexCircuit Switching Vs. packet switchingTDD Vs. FDDSymmetric Vs. Asymmetric TransmissionTDMA Vs FDMASpread Spectrum

Simplex Vs. Duplex

Fig. Simplex Scenario

Simplex Vs. Duplex

Fig. Duplex Scenario

While in Duplex we have access to both transmitter and receiver Simultaneously.

Mobile can Send and receive data Simultaneously

Circuit Switching Vs. packet Switching

Traditional Connection for Voice Communication requires that a Physical path Connecting the users at the end of the line and that path stays open until the Conversation ends. This is Called Circuit Switching.

Most Modern Technology Defers from this Traditional Model because they uses packet data.

Chopped into pieces

Given a destination address

Mixed with other data from other Source

Transmitted over channel with other data

Reconstructed at other end

Packet Data was originally developed for Internet.

WCDMAWorks in Two mode

TDD

Guard time

FDDGuard frequency

MS BS

FDD and TDD systems frequency allocation

Source: Information and Communication university.

freq

uen

cy

Time

FDD - WCDMA Improved performance over 2G systems:

Improved Capacity and coverage

Coherent uplink using a user-dedicated pilot

Fast power control in the downlink

Seamless inter-frequency handover

High degree of service flexibility:

Multi-rate service : with maximums of 144-384 Kb/s for full coverage and 2 Mb/s for limited coverage

Packet access mode

High degree of operator flexibility:

Support of asynchronous inter-base-station

Support of different deployment scenarios, including hierarchical cell structure (HCS) and hot-spot scenarios

Support of new technologies like multi-user detection (MUD) and adaptive antenna arrays (SDMA)

Symmetric vs. Asymmetric Transmission

Same Data rate for Uplink and downlink

Different Data Rate

WCDMA ParametersChannel bandwidth 5 MHz

Duplex mode FDD and TDD

Downlink RF channel structure Direct spread

Chip rate 3.84 Mbps

Frame length 10 ms

Data modulation QPSK (downlink), 8 PSKBPSK (uplink)

Channel coding Convolutional and turbo codes

Coherent detection User dedicated time multiplexed pilot (downlink and uplink), common pilot in the downlink.

Multirate Variable spreading and multicode

Spreading factors 4–256 (Downlink), 4–512 (Uplink)

Spreading (downlink) OVSF sequences for channel separationGold sequences 218 -1 for cell

Spreading (uplink) OVSF sequences, Gold sequence 241-1

Handover Soft handoverInterfrequency handover

Source: [21]

CDMA Transmitter And Receiver

Source of Information Transmitter D/A

IF/RF upconverter

Spreader

PN Code

Fig. Block diagram of the mobile transmitter

Sink Receiver Front End

Despreader 1

PN Code

Fig. Block diagram of the base station receiver

Selection of Code is Utmost Important

Spreading in WCDMA

an = c1 an-1 + c2 an-1 + ... + cr an-

Pseudo Random (PN) sequence: A bit stream of ‘1’s and ‘0’s occurring A bit stream of ‘1’s and ‘0’s occurring randomly, or almost randomly, with some unique properties.randomly, or almost randomly, with some unique properties.

Linear shift registerLinear shift register

an an-1 an-2 an-r

c1 c2 c3 cr

Spreading and Scrambling in WCDMA

Spreading: To multiply the input information bits by a PN code and get processing gain, the chip level signal’s bandwidth is much wider than that of input information bits. It maintains the orthogonality among different physical channels of each user.

Scrambling: To separate the signals from the different users. It doesn’t change the signal bandwidth. Each cell has a unique scrambling code in the system.

X XData

Spreading Scrambling

Bit Rate Chip Rate Chip Rate

S

P

Modulation Mapper

Downlink Physical Channel

Cch,SF,m

I

Q

J

I+JQ

Sdl,n

STo

Fig. Relation between spreading and scrambling [11]

Fig. Spreading for all downlink physical channels except SCH [11]

WCDMASelecting codes

high autocorrelation low cross correlation

Suppressing interference

Spreading in WCDMA OVSF Code and Gold Code

OVSF Code:Purpose: SpreadingGeneration Methedology: Code-Tree

Gold Code:Purpose: ScramblingGeneration: modulo-2 sum of 2 m-sequences

Fig. Auto and cross correlation of Gold Code

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

C4,4=1 -1 -1 1

Fig. Auto-correlation and cross correlation between

the OVSF codes of length 128

OVSF Code

Fig OVSF code Matrix of 4 ×4 length.

Fig OVSF code Matrix of 8 ×8 length.

Fig OVSF code plot for code number 6 from 128 ×128 OVSF code Matrix

Gold Code

Fig Scrambling code generation

A set of Gold codes can be generated with the following steps.

Pick two maximum length sequences of the same length such that their absolute cross-correlation is less than or equal to

where is the size of the LFSR used to generate the maximum length sequence (Gold '67).

Gold Code

Air Interface Protocol Architecture

Source: [6] Physical Channels

Logical ChannelBroadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Common Control Channel (CCCH)

Shared Channel Control Channel (SHCCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Traffic Channel (TCH)

Transport Channel Dedicated channels. Common channels.

Broadcast Channel (BCH)

Forward Access Channel (FACH)

Paging channel (PCH)

Random Access Channel (RACH)

Common Packet Channel (CPCH)

Downlink Shared Channel (DSCH)

Physical Channel Uplink Channels

Dedicated physical Channel Common physical Channel

• Downlink ChannelsDownlink Dedicated Physical Channel (DPCH)

Physical Downlink Shared Channel (DSCH)

Primary and Secondary Common Pilot Channels (CPICH)

Primary and Secondary Common Control Physical Channels (CCPCH)

Synchronization Channel (SCH)

Mapping of Transport channel into Physical Channel

Source: [3]

TFITransport

BlockTFI

Transport Block

TFI TFI

Transport Block & Error

Indication


Indication

Transport Block

Transport Block


Indication


Indication

TFCI Coding & MultiplexingTFCI

DecodingDecoding &

Demultiplexing

Physical Control ch

Physical data ch

Physical Control ch

Physical data ch

Transport Ch 1 Transport Ch 2

Higher Layers

Physical Layer

Transmiter Receiver

• The Transport Channels are Channel Coded and matched to the data rate offered by physical Channels.

Downlink Physical Channels

The length of a radio frame is 10 ms and one frame consists of 15 time slots.

The number of bits per time slot depends on the physical channel.

There is one downlink dedicated physical channel, one shared and five common control channels

Dedicated Downlink physical channel (DPCH)Physical downlink shared channel (DSCH)Primary and secondary common pilot channels (CPICH)Primary and secondary common control physical channels

(CCPCH)Synchronization channel (SCH)

Dedicated Downlink Physical Channel (DPCH)

Data 1Ndata1 bits

TPCNTPC bits

TFC1NTFC1 bits

Data2Ndata2 bits

PilotNpilot bits

DPDCH DPCCH DPDCH DPCCH

Tslot = 2560 chips, 10*2k bits (k=0...7)

One radio frame . Tf= 10 ms

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

Source: [25]

DPDCH and DPCCH Field

SlotFormat

#

Channel Bit rate(kbps)

Channel Symbol

rate (ksps)

SF Bits/slot DPDCH Bits/slot DPCCH Bits/slot TransmittedSlot per

Radio frame NTrNData1 NData2 NTPC NPilot NTFC1

0 15 7.5 512 10 248 1000 8 16 8 15

Source: [25]

Downlink Dedicated Physical channel

(DPCH)

Fig. Data After SpreadingFig Data after Scrambling

Simulation of Downlink Channels

Generation of Data

Mapped to I and Q branch

Adjust into Frame by Adding TPC, TFCI bits……

Spreading & Scrambling

Divide to Real and Imag branch

Modulation

Methodology.

DPCH

According to 3GPP standards, one slot (10ms/15 = .666 ms) layout is asfollows:

|--Data1--|--TPC--|--TFCI--|--Data2--|--pilot--| | 248 | 8 | 8 | 1000 | 16 |

Total bits = 1280, SF=4 ==>num_chips=1280*4=5120chips/slot

Channel rate is 1280(bit/slot)*15(slot) =1920 kbps.

To form a slot and then a frame we need to break our data stream into248-1000-248-1000.........according to Data1 and Data2(format#0).

Common Downlink Physical channel Common Pilot Channel (CPICH) P-CPICHS-CPICH

Slot #0 Slot#1 Slot #14

Tslot = 2560 chips, 20 bits =10 symbols


Pre-defined symbol sequence

Slot#i

Fig Common Pilot Channel (CPICH) [25]

Common Control Physical Channel

Primary-CCPCH


Tslot = 2560 chips, 20 bits


DataNdata1= 18 bits

Slot#i

Tx OFF

256 chips

• Secondary-CCPCH


Tslot = 2560 chips, 20*2k bits (k=0..6)


DataNdata1 bits

Slot#i

TFC1NTFC1 bits

PilotNpilot bits

Fig Primary-CCPCH [25] Fig Secondary-CCPCH [25]

Synchronisation Channel (SCH)The Synchronisation Channel (SCH) is a

downlink signal used for cell search. Consists of Two Channel

acp

acs I,0

acp

acs I,1

acp

acs I,14

Slot #0 Slot #1 Slot # 14

256 chips

2560 chips

One 10 ms SCH radio frame

Primary SCH

Secondary SCH

Fig. Structure of Synchronisation Channel (SCH) [25]

Synchronisation Code GenerationPSCDefine:a = <x1, x2, x3, …, x16>

a= <1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1 >

Now PSC is Defined as

Cpsc = (1 + j) × <a, a, a, -a, -a, a, -a, -a, a, a, a, -a, a, -a, a, a>

Synchronisation Code Generation SSC Define

z = <b, b, b, -b, b, b, -b, -b, b, -b, b, -b, -b, -b, -b, -b>

where

b = <x1, x2, x3, x4, x5, x6, x7, x8, -x9, -x10, -x11, -x12, -x13, -x14, -x15, -x16>

The Hadamard sequences

0 (1)H

1 1

1 1

k kK

k k

H HH

H H

Synchronisation Code Generation

The k:th SSC, Cssc,k = 1, 2, 3, …, 16 is then defined as:

m=16*(k-1)

Cssc,k = (1 + j) × <hm(0) × z(0), hm(1) × z(1), hm(2) × z(2), …, hm(255) × z(255)>

Scrambling Code Group

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

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

PSCH Search

Fig PSCH search

Transmitter

Σ

Σ

Different DownlinkPhysical Channels

G2

G2

Gp

Gs

P-SCH

S-SCH

T

Fig. Combining Different Downlink Physical channel [26]

Complex ValuedChip sequenceFrom summing

operation

Re{T}

Im{T}

Pulse Shaping

Pulse Shaping

SplitReal

&Imaginary

Parts

Cos(ωt)

-Sin(ωt)

QPSKModulated output

Fig. Modulation in WCDMA [26]

Square Root Raised Cosine Filter

Fig. Magnitude response of Square-Root Raised Cosine Filter Fig. Phase response of Square-Root Raised Cosine Filter

Fig. Impulse response of Square-Root Raised Cosine Filter Fig. Step response of Square-Root Raised Cosine Filter

Square Root Raised Cosine filter

It is characterised by two values; , the roll-off factor, and , the reciprocal of the symbol-rate.

Square Root Raised Cosine Response

Square Root Raised Cosine Filter

Fig. Pole/Zero Plot of Square-Root Raised Cosine Filter

QPSK modulation of DPCH

Fig. DPCH I channel Modulated by Cos(ωt) Fig DPCH Q channel Modulated by –Sin(ωt)

Fig Transmitted signal Constellation

Primary Common Control Physical Channel (P-CCPCH)

Fig. Primary Common Control Physical Channel with SSC I branch

Fig. Primary Common Control Physical Channel with SSC Q branch

Secondary-CCPCH

Fig. Secondary Common Control Physical Channel I branch

Fig. Secondary Common Control Physical Channel Q branch

Questions

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Reference[1] J. Schiller, “Mobile Communication”, second edition Pearson Education Private LTD.

[2] Rudolf Tanner and Jason woodword, “WCDMA Requirements and practical design”, John Wiley and Sons LTD.

[3] Holama H. and Toskala A. “WCDMA for UMTS”, John Wiley and Sons LTD.

[4] T Rappaport, “Wireless Communications, Principles and Practices”, Second Edition, Prentice Hall, 2002.

[5] Viterbi Andrew J “CDMA: Principles of spread spectrum communication”, second edition prentice hall LTD.

[6] Proakis J. G. “Digital Communication”, third edition prentice hall LTD.

[7] M. R. Karim and Sarraf M., “W-CDMA and CDMA 2000 for 3G Mobile Networks”, McGrawHill, 2002.

[8] Stallings, W. 2001. “Wireless Communications and Networks” Prentice Hall LTD.

[9] Widrow, B., & Stearns, S.D. 1985 “Adaptive Signal Processing” Prentice Hall: New Jersey

[10] Haykin, S. 2002. “Adaptive Filter Theory” Prentice Hall: Eaglewood Cliffs

Reference[8] E. Berruto, M. Gudmundson, R. Menolascino, W. Mohr, and M. Pizarroso, “Research activities on UMTS radio interface,

network architectures, and planning,” IEEE Commun. Mag., vol. 36, pp. 82–95, Feb. 1998.

[9] D. Grillo, Ed., “Special section on third-generation mobile systems in Europe”,” IEEE Personal Commun. Mag., vol. 5, pp. 5–38, Apr. 1998.

[10] Bahl P. and Girod B., Eds., “Special section on wireless video,” IEEE Commun. Mag., vol. 36, pp. 92-151, June 1998.

[11] W. Mohr and S. Onoe, “The 3GPP proposal for IMT-2000,” IEEE Commun. Mag., pp. 72-81, Dec. 1999.

[12] Homer, J., Bitmead, R.R., & Mareels, I. 1998. “Quantifying the effects of dimension on the convergence rate of LMS adaptive FIR estimator,” IEEE Transactions on Signal Processing, 46 (10): 2611-2615

[13] Homer, J. 1998. “A review of the developments in adaptive echo cancellation for telecommunications,” Journal of Electrical and Electronics Engineering, Australia, 18(2): 149-164

[14] Homer J., Mareels I., Bitmead R.R., Wahlberg B., & Gustafsson F. “LMS estimation via structural detection” IEEE Transactions on Signal Processing, 46(10): 2651-2663, 1998

[15] A.J. Viterbi, “The Evolution of Digital Wireless Technology from Space Exploration to Personal Communication Ser vices,” IEEE Trans. Veh. Technol., Vol. 43, No. 3, pp. 638—644, August 1994.

[16] D.L. Schilling, “Wireless Communication Going into the 21st Century,” IEEE Trans. Veh. Technol., Vol. 43, No. 3, pp. 645-652, August 1994.


[18] B. Girod and N. F¨aber, “Feedback-based error control for mobile video transmission,” IEEE Proceedings, vol. 87, pp. 1707-1723, Oct. 1999.

[19] A.J. Viterbi, “The Evolution of Digital Wireless Technology from Space Exploration to Personal Communication Ser vices,” IEEE Trans. Veh. Technol., Vol. 43, No. 3, pp. 638—644, August 1994.

Reference[20] D.L. Schilling, “Wireless Communication Going into the 21st Century,” IEEE Trans. Veh. Technol., Vol. 43, No. 3, pp.

645-652, August 1994.


[22] Zhang X., Gang. H., “Strategies of improving QoS for Video Transmission over 3G Wireless Network”, Hohai university.

[23] Cherriman P., Hanzo L., “ Robust H.263 Video Transmission over Mobile Channels In interference Limited Environment”, 1st IEEE wireless video communication workshop.

[24] Gharvi H., “Video Transmission for Third Generation Mobile Communication Systems”, Milcom, 2001.

Reference [3GPP Technical specification]

[25] 3GPP TSG Technical Specification TS 25.211 “Physical channels and mapping of transport channels”.

[26] 3GPP TSG Technical Specification TS 25.213 “Spreading and modulation”

[27] 3GPP TSG Technical Specification TS25.212 “Multiplexing and channel coding (FDD)”

[28] 3GPP TSG Technical Specification TS 25.214 “Physical layer procedures (FDD)”

Reference [Websites]

[29] CDMA Development Group. 2002. RAKE Receiver: Another Advantage of CDMA over Other Systems. http://www.cdg.org/tech/abcs/lec1/text/abc_1_3_36.txt [Accessed Oct 14 2002].

[30] CDMA seminars on www.cdmaonline.com

[31] WCDMA chapter-6: www.privateline.com/3G/WCDMA.pdf

Thank You

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