1.wo bt01 e1 1 umts radio theory-63
DESCRIPTION
Teoria de UMTSTRANSCRIPT
UMTS Radio Theory
ZTE University
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
Radio Transmission Technology Requirements Data :
144 kbps High speed and driving 384 kbps Modest speed and walking 2 Mbps Low speed and indoor
Voice 4.75Kb/s -- 12.2Kb/s 64kb/s (Video Phone)
Information transmission at variable rate according to bandwidth requirements ;
Delay requirements of different service
3G services
Delay
Bit ErrorDifferent QOS requirements
3G services Categories Actual Service Delay (One-way) Bearer Speed
conversational
Voice <150ms 12.2kbps
Video Call <150ms 64kbps
VoIP <150ms 15.3~39.6kbps
Interaction Game
<250ms N/A
Streaming
Real-time Voice Streaming
<2s 4.7~25kbps
Real-time Video Streaming
<2s 64kbps~2Mbps
Interaction
Web Browsing <4s N/A
WAP Browsing <4s N/A
E-commerce <4s N/A
BackgroundFTP No strict N/A
E-mail No strict N/A
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
Duplex mode
TDD mode - uplink and downlink has the same frequency Adaptable to any frequency
band Suitable for both asymmetric
and symmetric services FDD mode - uplink and downlink
has the different frequency Paired frequency bands are
needed Suitable for symmetric services
TDD ( Time division duplex,Such as TD-SCDMA)
D D D D U U UU
FDD ( Frequency division duplex, Such as WCDMA and CDMA2000 )
D D D D D D DD
U U U U U U UU
Why Multiple Access? Increased capacity: serve more users Reduced capital requirements since
fewer media can carry the traffic Decreased per-user expense
Types of Transmission Medium: Twisted pair Coaxial cable Fiber optic cable Air interface (radio signals) Three methods are frequently used: FDMA TDMA CDMA
Each pair of users enjoys a dedicated, private circuit through the transmission medium, unaware that theother users exist.
Transmission
Medium
Multiple access technologies enable various users access public communication line but without interference.
Multiple Access Technologies
Users are using Users are using different frequencydifferent frequency
Time
Frequency
FDMA
FDMA (Frequency Division Multiple Access)
FDMA Traffic channels are assigned to different users at
different frequency band, such as TACS, AMPS.
Time
Frequency
TDMA
Users are using Users are using different time slotdifferent time slot
TDMA (Time Division Multiple Access)
TDMA Traffic channels are assigned to different users at
different time, such as GSM, DAMPS.
Time
Frequency
CDMA
Code
Users are using different Users are using different orthogonal code sequenceorthogonal code sequence
CDMA (Code Division Multiple Access)
CDMA Traffic channels are assigned to users at same time,
same frequency band, but with different code.
Freq. 1
Freq. 1
Code A
Code B
Code
C
BS1
BS2
Code D
Code E
CDMA Application
Users are distinguished by scrambling codes and OVSF codes
Self-interference system CDMA system is restricted to interference (GSM system is
restricted to frequency resources)
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
GSM900/1800: 3G (W CDM A):
Single Frequency Network
IMT-2000 Spectrum Allocation
1850 1900 1950 2000 2050 2100 2150 2200
ITU
Europe
USA MSSPCS
A D B BC D CE F A FE MSSReserveBroadcast auxiliary
2165 MHz1990 MHz
1850 1900 1950 2000 2050 2100 2150 2200
UMTSGSM 1800 DECT MSS
1885 MHz 2025 MHz
2010 MHz
IMT 2000
MSSUMTS
Japan MSSIMT 2000MSSIMT 2000PHS
IMT 2000
2110 MHz 2170 MHz
MSS MSS
FDD MSSMSSTDD TDD
1980
GSM1800 FDD
1920
China
1880
1865
1870
1885
1890
1910
1930
1945
1965
1970
1975
3G Spectrum Allocation in China
60 MHz30 MHz
FDD TDD
100 MHz15MHz
40 MHz
155MHz
1785 18501755 1880 1920 1980 2010 2025 2110 2170 2200 2400
Satellite Empty Satellite
2300
3G Spectrum Planning in China
Main Operating Frequency Band : FDD mode : 1920-1980 MHz / 2110-2170 MHz TDD mode : 1880-1920MHz 、 2010-2025 MHz
Supplementary Operating Frequency Band : FDD mode : 1755-1785 MHz / 1850-1880 MHz TDD mode : 2300-2400MHz
Frequency Band for Satellite Mobile Communication System : 1980-2010 MHz / 2170-2200 MHz
The frequency bands, 825 - 835 MHz / 870 - 880 MHz, 885 - 915 MHz / 930 - 960 MHz and 1710 - 1755 MHz / 1805 - 1850 MHz, which are currently allocated to public mobile communication system are also allocated to expanded frequency bands of 3G public communication system, but frequency using mode remains the same for both uplink and downlink.
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
SHANON Formula
C = Blog2(1+S/N)
Spread Spectrum Principles
Where, C is capacity of channel, b/s B is signal bandwidth, Hz S is average power for signal, W N is average power for noise, W It is the basic principle and theory for spread spectrum
communications.
Spread Spectrum Principles
5 MHz12 KHz
Power is “Spread” Over a Larger BandwidthMATHHAMMER
MATHHAMMER
radio channel
ReceiverTransmitter
SpreadingDespreading
Noise
Spread Spectrum Principles
User information bits are spread over a wide bandwidth by multiplying high speed spread code(chip)
Spread signal bandwidth W wider than original signal bandwidth Rb
f
S ( f )
f0Before spreading
signal
S ( f )
ff0After spreading
signal
S ( f )
ff0After despreading
signalWhite noise
f
S ( f )
f0Before despreading
signalWhite noise
signal interference White noise
Spread Spectrum Principles
Spreading Mode
Direct sequence spread spectrum ( DS-SS ) Base band data is spread by multiplication of pseudo-noise
sequence and base-band pulse, the pseudo-noise sequence generated by the pseudo-noise generator
BER subject to Multiple Access Interference and near-far effect Power control can overcome the near-far effect, but it is limited
by power detection accuracy WCDMA uses DS-SS
Frequency hopping spread spectrum ( FH-SS ) Data is transmitted in the random channel by the carrier
frequency hopping Before FH again, data is transmitted using traditional
narrowband modulation No near-far effect
DS-SS communication system
A technology of transmission after spreading signal spectrum.
FastSpreadingSequence
SlowInformation
Sent
TX
SlowInformationRecovered
RX
FastSpreadingSequence
WidebandSignal
Spread Spectrum Principles
Many code channels are individually“spread” and then added together tocreate a “composite signal”
Unwanted Power from Other Resoures
Spread Spectrum Principles
Any Code Channel can be extracted from the received composite signal by using the “right” orthogonal code
Energy for transmitting signal can be lower than interference and noise
Processing Gain
Broadband Interference
Concept of orthogonal code
Orthogonal—the result of multiplying and sum is 0
Code1 +1 -1 +1 +1 -1 +1 -1 -1
Code2 -1 +1 +1 -1 -1 +1 +1 -1
Mul -1 -1 +1 -1 +1 +1 -1 +1
Sum 0Orthogonal
Code1 +1 -1 +1 -1 -1 +1 -1 -1Code2 +1 +1 -1 +1 -1 -1 +1 -
1Mul +1 -1 -1 -1 +1 -1 -1 +1Sum -2
Non-orthogonal
-1 1 -11-1 -11 1 -1 -1 11-1 1-1 1MUL-1 1 -11-1 -11 1
1 -1 1 -1
-4 40 0
Judge -1 1
1 -1 1 -1
-1 1 MUL
Integral
1 1 1 1-1 -1 -1 -1
Example of orthogonal code
S1S1
S2S2
S1xC1S1xC1
S2XC2S2XC2
WW Spreading
Despreading(S1xC1)+(S2xC2)(S1xC1)+(S2xC2)
Air InterfaceAir Interface
[S1xC1+S2xC2]x[S1xC1+S2xC2]xC2C2
==S2S2
[S1xC1+S2xC2]xC[S1xC1+S2xC2]xC11
==S1S1 NN SS
C1xC2=0,C1,C2,orthogonal
Direct spread technique
Spreading code =1 -1 -1 1 -1 1 1 -1 ( SF = 8 )
Symbol
Spreading
Despreading
1-1
1-1
1
-1
1-1
1-1
Data=010010
Spreading code
Spread signal= Data × code
Data =Spread signal ×Spreading code
Chip
Sketch map of Spreading and Despreading
Characteristics of Spreading Communication
High anti-multi-path- interference capability Anti-sudden-pulse High security Lower transmitting power Easy to implement large-capacity Multiple Access
Communication Occupy band wide Complex realization
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
Purpose of Channel Coding
By adding redundant information in the original data stream, receivers can detect and correct the error signal, and improve data transmission rates.
No correct coding: BER<10-1 ~ 10-2Can not satisfy
the communication
Convolutional coding : BER<10-3Can satisfy the
speech communication
Turbo coding : BER<10-6Can satisfy the
data communication
Principle of Channel Coding
Channel coding Error-correcting ability obtains by adding redundancy in the
original data Convolutional coding and Turbo coding ( 1/2 , 1/3 ) are
widely applied. Increase noneffective load and transmission time Suitable to correct few non-continuous errors
W C D M AT U R B OS P E A K
W W C C D D M M A AT T U U R R B B O OS S P P E E A A K K
W ? C C D D M M A A
T T ? U R R B B O O
S S P P E E A ? K K
Decoding
Encoding
Principle of Interleave Technology
advantage Interleave is to change the sequence of data to random the
unexpected errors Advance the correcting validity
disadvantage Increase the processing delay Especially, Several independent random errors may intertwined for
the unexpected error.
x1 x6 x11 x16 x21x2 x7 … x22x3 x8 … x23x4 x9 … x24x5 x10 … x25
Data input A = (x1 x2 x3 x4 x5 … x25)
Data output A’= (x1 x6 x11 x16… x25)
e.g.
Encoding and Interleaving
W C D M AT U R B OS P E A K
W W C C D D M M A AT T U U R R B B O OS S P P E E A A K K
W T S W T SC U P C U PD R E D R EM B A M B AA O K A O K
W ? ? C D D M M A ?T ? ? U R ? ? B O OS ? ? P ? E A A K K
Encoding Interleaving
W T S ? ? ?? ? ? C U PD R ? D ? EM ? A M B AA O K ? O K
DeinterleavingDecoding
Encoding + Interleaving can correct both continuous and non-continuous errors
Content
The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation
UMTS Radio mechanism
Principle of Modulation
Definition Modulation is the process where the amplitude,
frequency, or phase of an electronic or optical signal carrier is changed in order to transmit information.
Using symbol stand for one or more bits to improve communication effectiveness
Classification Analog Modulation Digital Modulation
Symbolbit Modulation
Analog Modulation
The purpose of analog modulation is to impress an information-bearing analog waveform onto a carrier for transmission. Common analog modulation methods include:
Amplitude modulation (AM) Frequency modulation (FM) Phase modulation (PM)
Digital Modulation
The purpose of digital modulation is to convert an information-bearing discrete-time symbol sequence into a continuous-time waveform (perhaps impressed on a carrier). Basic analog modulation methods include
Amplitude shift Keying (ASK) Frequency shift Keying (FSK) Phase shift Keying (PSK)
Content
The Basic Principles of Wireless Communication UMTS Radio mechanism
UMTS Data transmission Procedure Channel Coding of UMTS Spreading Technology of UMTS Modulation of UMTS
WCDMA Data transmission Procedure
RF ReceivingDemodulationDespreading
Decoding & De-inteleaving
UE Data
UE Data Spreading
RF Transmitting
Modulation
Baseband demodulation
Baseband modulation
Encoding & Interleaving
Content
The Basic Principles of Wireless Communication UMTS Radio mechanism
UMTS Data transmission Procedure Channel Coding of UMTS Spreading Technology of UMTS Modulation of UMTS
Mainly used in the voice channel and control signal channel
Coding rate is ½ and 1/3.
Output 0 G0 = 557 (octal)
Input D D D D D D D D
Output 1 G1 = 663 (octal)
Output 2 G2 = 711 (octal)
Rate 1/3 convolutional coder
Convolutional Code
Easy decode Short delay Generally use the Viterbi Algorithm Channel bit error rate is 10 - 3 magnitude Suitable to realtime service
e.g. speech and video service.
Characteristics of Convolutional code
Used in Data service channel Code Rate is 1/3 Can be implemented in the transmission for large block and long
delay services Turbo coding structure is based on two or more weak error
control code combinations. The information bits are interleaved in the two Encoder, and generate two information flow. At last, this information can be multiplexed and punctured
Decoding needs cycle iterative calculation
InterleaverEncoder 1
Encoder 2
Mul
tiple
x
inputoutput
Turbo Code
Complex decoding Use the LOG-MAP arithmetic Channel bit error rate is 10 - 6 magnitude Very suitable to non-realtime package service
which is BER sensitive & delay insensitive, e.g. WWW, FTP, E_mail, multimedia transmission.
Characteristics of Turbo Codes
Content
The Basic Principles of Wireless Communication UMTS Radio mechanism
UMTS Data transmission Procedure Channel Coding of UMTS Spreading Technology of UMTS Modulation of UMTS
Symbol rate × SF = Chip rate=3.84McpsFor UMTS , SF of uplink channelization code : 4~256
SF of downlink channelization code: 4~512
OVSF: Orthogonal Variable Spreading Factor
OVSF Code Scrambling Code
Data Spread Data
Spreading Process of UMTS
Symbol Chip
3.84Mcps
3.84Mcps
Channelization Code
Adopt OVSF code Definition: Cch,SF,k, describe channelization code, where
SF : spread factor , k : code number, 0 < k<SF-1
SF = 1 SF = 2 SF = 4
C ch,1,0 = (1)
C ch,2,0 = (1,1)
C ch,2,1 = (1,-1)
C ch,4,0 =(1,1,1,1)
C ch,4,1 = (1,1, -1, -1)
C ch,4,2 = (1, -1 ,1, -1)
C ch,4,3 = (1, -1, -1, 1)
Scrambling Code
UMTS Scrambling code is pseudo random binary sequence It has similar noise array character, seemingly random
but with regularity. Can make the user data further random , strengthened
by scrambling a code to keep secret the user data, at the same time easy to carry out multiple access communication.
UMTS scrambling code is generated from Gold sequence Gold sequence has excellent self-correlation. Cross-correlation is very week between two codes. It is used to identify cell and user for multiple access.
Characteristic of Scrambling code
There are 224 Uplink Scrambling Codes, they are used to distinguish different users in one cell.
There are 218-1 Downlink Scrambling Codes, used to distinguish different cells Scrambling codes usually used are the first 8192 codes,
which are code 0 , 1 ,……, 8191. They are divided into 512 aggregations , each aggregation has 1 primary scrambling code (PSC) and 15 secondary scrambling codes (SSC).
The 512 primary scrambling codes are divided further into 64 primary scrambling code groups , with 8 primary scrambling codes in each group.
Numbering rule for Downlink Scrambling Codes
…
218-1 Downlink Scrambling Codes in all(0..262142)
No. 511 Scrambling Code Group
81768177
8191
8176 : PSC8177 : SSC…8191 : SSC
No. 510 Scrambling Code Group
81608161
8175
8160 :主扰码8161 :辅扰码…8175 :辅扰码
No. 504 Scrambling Code Group
80648065
8079
8064 :主扰码8065 :辅扰码…8079 :辅扰码
…
No. 7 Scrambling Code Group
112113
127
8176 : PSC8177 :辅扰码…8191 :辅扰码
No. 1 Scrambling Code Group
1617
31
16 : PSC17 : SSC…31 : SSC
No. 0 Scrambling Code Group
01
15
0 : PSC1 : SSC…15 : SSC
No.63 Primary Scrambling Code Group … …
No.0 Primary Scrambling Code Group
Code Functions
Channelization code ---- for separation of physical channels in the uplink and separation of users in the downlink
Scrambling code ---- for separation of users/terminals in the uplink and cells/sectors in the downlink.
Air Interface
2chc
3chc
1chc
scramblingc Modulation
Spreading code & scrambling code
Cch : spread code Relative to service rate , extended to 3.84Mchips/s A kind of orthogonal code
Cscrambling : scrambling code Have no effect on signal bandwidth Downlink for identifier cell , uplink identifier terminal A pseudo-random sequence
f
P
W
Processing Gain
Rb
Despreading
Processing Gain
PG=Wc/Rb (Wc : Chip rate , Rb : Service bit rate) Transmitter/receiver can obtain gain after
spread/despread The narrower original signal bandwidth, the larger Pg ,
the betterThe higher PG, the more anti-interference capability system has.
b
c
RWGain Processing
Eb =Signal Power
Bit Rate = SR
E / tB / t
= N0 =Noise PowerBandwidth = N
W
Eb
N0
=
SR
NW
=SR X
WN =
SN X W
R
Signal to Noise
Processing Gain
The more the expansion multiples, the higher the processing gain, the stronger the anti-jamming capability
Relation between Eb/N0 and PG
Despreading procedure
Method of despreading
Input signal
Local PN code
When T=Ts, judge
Output after despreading
integral
0
Ts(*)dt
Content
The Basic Principles of Wireless Communication UMTS Radio mechanism
UMTS Data transmission Procedure Channel Coding of UMTS Spreading Technology of UMTS Modulation of UMTS
Modulation Methods in UMTS
BPSK (Binary Phase Shift Keying) in Uplink channles QPSK (Quadrature Phase Shift Keying) in Downlink channels 16QAM (16-state Quadrature Amplitude Modulation) in HSDPA
Physical Channel Spread-Spectrum Modulation Process-Downlink
∑ ∑
Separationof realPartsAnd
Imaginaryparts
PulseForming
PulseForming
SerialParallelSwitch
SerialParallelSwitch
……
……
Downlink physical channel 1
Cch,SF,m
j
I+jQSdl,n
G1
Cch,SF,m
j
I+jQSdl,n
G2Downlink
physical channel 2
Gp
Gp
P-SCH
S-SCH
cos(wt)
-sin(wt)
Re(T)
Im(T)
Physical Channel Spread-Spectrum Modulation Process-Uplink
Separationof realPartsAnd
Imaginaryparts
PulseForming
Pulse Forming
cos(wt)
-sin(wt)
Sdpch,n
Re(S)
Im(S)
∑
Cd,1 βd
I
cc
Q
j
I+jQ
∑
∑
DPDCH1Cd,3 βd
DPDCH3 Cd,5 βdDPDCH5
Cd,2 βdDPDCH2Cd,4 βd
DPDCH4 Cd,6 βdDPDCH6
ccCc βc
DPCCH
Q