Transcript “Simulation of 3G Air Inteface Wideband Coded

As Part of Pedagogy Activity in EC Department, 2011, 2012
Simulation and Analysis of 3G Air interface
Wideband Coded Division Multiple Access working in
Downlink FDD
4th August, 2012
Presented By:
Prof. Amit Degada
[email protected]
Electronics and Communication Department,
Institute of Technology,
Nirma University,
Ahmedabad-382481.
ज्ञानं ज्ञेयं परिज्ञाता त्रिविधा कर्म च यत्तु दना
।
किणं कर्म कतेतत त्रिविधः कर्मसंग्रहःः ॥१८- १८॥
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)
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
The Objective of the Lecture
 How the Technology has evolved.
 Various Air Interfaces of 3G
 Physical Layer of WCDMAWorking In Downlink FDD
First Mobile Radio Telephone
Today’s Mobile
Source:www.gsmarena.com
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
Migration to 3G
Migration to 3G
Source: univ.zte.com/cn
3GPP- A Global Initiative
3GPP - Third Generation Partnership
Project
ARIB - Association of Radio Industries
and Businesses
CWTS - China Wireless
Telecommunication Standard group
ETSI - European Telecommunications
Standards Institute
T1 - Standards Committee T1
Telecommunications
TTA - Telecommunications Technology
Association
TTC - Telecommunication Technology
Committee
IETF - Internet Engineering Task Force
ITU-R - International
Telecommunication Union Radiocommunication
ITU-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
User
Equipment:
Mobile Equipment : Radio Transmission & contains applications.
Mobile Termination, Terminal Equipment
USIM : Data and Procedures which unambiguously and securely identify itself in Smart
Card.
3GPP Rel.6 Objectives
 Migration from GSM based Network to 3G standard
WCDMA
 Scope and definition in progress
 IP Multimedia Services, phase 2
 „IMS messaging and group management
 Wireless LAN interworking
 Speech enabled services
 „Distributed speech recognition (DSR)
 Number portability
 Other enhancements
3GPP2 Defines
 3rd 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
WCDMA
CDMA2000
CDMA 2000
3G
TD-SCDMA
standards
UWC
CDMA is the main technology of 3G
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
Architecture of channel Adaptive
Hybrid ARQ/FEC
R ( n)  Ropt ( n  rttn) 
Ropt ( n  rttn)  R ( n  rttn )
2
CDMA Vs. WCDMA
Concepts We have to know
 Simplex Vs. Duplex
 Circuit Switching Vs. packet switching
 TDD Vs. FDD
 Symmetric Vs. Asymmetric Transmission
 TDMA Vs FDMA
 Spread 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.
WCDMA
 Works in Two mode
FDD and TDD systems frequency allocation
frequency
Guard frequency
MS
FDD
BS
Guard time
TDD
Time
Source: Information and Communication university.
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
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
WCDMA Parameters
Channel 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 PSK
BPSK (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 separation
Gold sequences 218 -1 for cell
Spreading (uplink)
OVSF sequences, Gold sequence 241-1
Handover
Soft handover
Interfrequency handover
Source: [21]
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
CDMA Transmitter And Receiver
Spreader
Source of
Information
Selection of
Code is Utmost
Important
Transmitter
D/A
IF/RF
upconverter
PN Code
Fig. Block diagram of the mobile transmitter
Despreader 1
Sink
Receiver Front End
PN Code
Fig. Block diagram of the base station receiver
Spreading in WCDMA
Pseudo Random (PN) sequence:
A bit stream of ‘1’s and ‘0’s occurring
randomly, or almost randomly, with some unique properties.
Linear shift register
an
an-1
c1
an-2
c2
an-r
c3
cr
an = c1 an-1 + c2 an-1 + ... + cr an-
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.
Spreading
I
Scrambling
S
Downlink Physical
Channel
Data
Bit Rate
X
X
Chip Rate
To
Modulation
Mapper
P
Sdl,n
I+JQ
Cch,SF,m
S
Q
Chip Rate
J
Fig. Relation between spreading and
scrambling [11]
WCDMA
Fig. Spreading for all downlink physical channels except SCH [11]
Selecting codes
high autocorrelation low cross correlation
Suppressing
interference
Spreading in WCDMA
 OVSF Code and Gold Code
OVSF Code:
Purpose: Spreading
Generation Methedology:
Code-Tree
C4,1=1 1 1 1
C2,1=1 1
C4,2=1 1 -1 -1
C1,1= 1
C4,3=1 -1 1 -1
C2,2=1 -1
Fig. Auto-correlation
and cross correlation between
the OVSF codes of length 128
C4,4=1 -1 -1 1
Gold Code:
Purpose: Scrambling
Generation: modulo-2 sum of 2 m-sequences
Fig. Auto and cross correlation of Gold Code
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
Gold Code
 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).
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
Air Interface Protocol Architecture
Physical Channels
Source: [6]
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
Logical Channel
Control
Channel
(CCH)
Broadcast 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)
Traffic
Channel
(TCH)
Dedicated Traffic Channel (DTCH)
ODMA Dedicated Traffic Channel (ODTCH)
Common Traffic Channel (CTCH)
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 Channels
Downlink 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
Transport Ch 2
Transport Ch 1
TFI
Transport
Block
Transport
Block
Transport
Block & Error
Indication
Transport
Block
Transport
Block
Transport
Block & Error
Indication
TFI
TFI
TFI
Transport
Block & Error
Indication
Transport
Block & Error
Indication
Higher Layers
Physical Layer
TFCI
Coding & Multiplexing
Physical
data ch
Physical
Control ch
Transmiter
TFCI
Decoding
Decoding &
Demultiplexing
Physical
data ch
Physical
Control ch
Receiver
Source: [3]
• 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)
DPCCH
DPDCH
Data 1
Ndata1 bits
TPC
NTPC bits
TFC1
NTFC1 bits
DPDCH
DPCCH
Data2
Ndata2 bits
Pilot
Npilot bits
Tslot = 2560 chips, 10*2k bits (k=0...7)
Slot #0
Slot#1
Slot#i
Slot #14
One radio frame . Tf= 10 ms
Source: [25]
DPDCH and DPCCH Field
Slot
Format
#
0
Channel
Bit rate
(kbps)
15
Channel
Symbol
rate
(ksps)
SF
7.5
512
Bits/slot
10
DPDCH Bits/slot
DPCCH Bits/slot
NData1
NData2
NTPC
NPilot
NTFC1
248
1000
8
16
8
Source: [25]
Transmitted
Slot per
Radio frame
NTr
15
Downlink Dedicated Physical channel (DPCH)
Fig. Data After Spreading
Fig Data after Scrambling
Simulation of Downlink Channels
Methodology.
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
DPCH
According to 3GPP standards, one slot (10ms/15 = .666 ms) layout is as
follows:
|--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 into
248-1000-248-1000.........according to Data1 and Data2(format#0).
Common Downlink Physical channel
 Common Pilot Channel (CPICH)
 P-CPICH
 S-CPICH
Pre-defined symbol sequence
Tslot = 2560 chips, 20 bits =10 symbols
Slot #0
Slot#1
Slot#i
Slot #14
One radio frame . Tf= 10 ms
Fig Common Pilot Channel (CPICH) [25]
Common Control Physical Channel
• Secondary-CCPCH
 Primary-CCPCH
256
chips
TFC1
NTFC1 bits
Data
Ndata1= 18 bits
Tx OFF
Data
Ndata1 bits
Tslot = 2560 chips, 20*2k bits (k=0..6)
Tslot = 2560 chips, 20 bits
Slot #0
Slot#1
Slot#i
Pilot
Npilot bits
Slot #14
One radio frame . Tf= 10 ms
Fig Primary-CCPCH [25]
Slot #0
Slot#1
Slot#i
Slot #14
One radio frame . Tf= 10 ms
Fig Secondary-CCPCH [25]
Synchronisation Channel (SCH)
 The Synchronisation Channel (SCH) is a downlink signal used
for cell search.
 Consists of Two Channel
Slot #0
Primary
SCH
Secondary
SCH
Slot #1
Slot # 14
acp
acp
acp
acs I,0
acs I,1
acs I,14
256 chips
2560 chips
One 10 ms SCH radio frame
Fig. Structure of Synchronisation Channel (SCH) [25]
Synchronisation Code Generation
 PSC
 Define:
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
H 0  (1)
 Hk  1 Hk  1 
HK  

 Hk  1  Hk  1
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
Group 0
#0
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
#11
#12
#13
#14
1
1
2
8
9
10
15
8
10
16
2
7
15
7
16
PSCH Search
Fig PSCH search
Presentation Outline
The Objective
Standardization Body
Motivation to work
WCDMA Parameters
CDMA Transmitter and Receiver: A General Approach
Air Interface Architecture
WCDMA Channels
WCDMA Transmitter
Transmitter
Different Downlink
Physical Channels
G2
Σ
G2
Σ
P-SCH
T
Gp
S-SCH
Gs
Fig. Combining Different Downlink Physical channel [26]
Cos(ωt)
Re{T}
Complex Valued
Chip sequence
From summing
operation
Split
Real
&
Imaginary
Parts
Pulse
Shaping
QPSK
Modulated output
Im{T}
Pulse
Shaping
-Sin(ωt)
Fig. Modulation in WCDMA [26]
Square Root Raised Cosine Filter
Fig. Magnitude response of Square-Root Raised Cosine Filter
Fig. Impulse response of Square-Root Raised Cosine Filter
Fig. Phase 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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[2]
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[3]
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[4]
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[20]
D.L. Schilling, “Wireless Communication Going into the 21st Century,” IEEE Trans. Veh. Technol., Vol. 43, No. 3, pp.
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[21]
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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