ee4650 通訊系統實驗 -...
TRANSCRIPT
-
EE4650: , Instructor: Prof. , [email protected]
Lab8ChannelCodec
EE4650
-
EE4650: , Instructor: Prof. , [email protected]
2
Lab8:(ChannelCodec)
ErrorCorrectioncoding
DigitalModulation D/A
A/D
PABPF
AWGN
BPF LNAError
Correctiondecoding
DigitalDemodulation
cos(2fct)
cos(2fct)
Info
0101
RFFrontendBasebandTx
BasebandRx RFFrontend
010110
0101100101
FadingChannel
-
EE4650: , Instructor: Prof. , [email protected]
(Convolution
Codes)
LabVIEW FullDevelopmentSystemLabVIEWModulationToolkit3.1(andup) NIUSRP2920
-
EE4650: , Instructor: Prof. , [email protected]
WhatisChannelCoding
ChannelCodingErrorCorrectionCodes
ChannelCodingBlockCodesConvolutionCodes
kdatabitsncodeword kbitsInformationBits knbitsParitycheckBitsCoderatek/n
-
EE4650: , Instructor: Prof. , [email protected]
ConvolutionCodes
kdatabits L1LConstraint
Length) Convolutioncodes(n,k,L)parameter bits3( )n=3 k=1 2register( )L=2+1=3 (n,k,L)=(3,1,3)
1n 3n2n
0m 1m
-
EE4650: , Instructor: Prof. , [email protected]
GeneratorMatrix GeneratorMatrixmatrixGmatrix
n k encoder3 1
10111register0i
1n1G 1 1 1 2 0 1 1G 3 1 0 1G
1, 1, 0, 1, 1i i i in m m m G
2, 1, 0, 1, 2i i i in m m m G
3, 1, 0, 1, 3i i i in m m m G
1
2
3
1 1 1 70 1 1 31 0 1 5
GG G
G
= = =
-
EE4650: , Instructor: Prof. , [email protected]
i
1 1 0 0 1 0 12 0 1 0 1 1 03 1 0 1 0 1 04 1 1 0 0 1 15 1 1 1 1 0 0
1,im 0,im 1,im 1,in 2,in 3,in
1,1 1 0 0 1 1 1 1Tn
2,1 1 0 0 0 1 1 0Tn
3,1 1 0 0 1 0 1 1Tn etc
Ex: Input:1,0,1,1,1
-
EE4650: , Instructor: Prof. , [email protected]
DecoderwithViterbi Algorithm Viterbi Algorithm
encodertrellisdiagram
state
0,im 1,im0S
1S
2S
3S
0, 0im 1, 0im
0, 0im 1, 1im
0, 1im 1, 0im
1, 1im 0, 1im
22 4
-
EE4650: , Instructor: Prof. , [email protected]
TrellisDiagram input 0 convolution
encoderencoderoutput000
register
1 convolutionencoderencoderoutput101
register
1i 0, 1 1, 0i im m
1, 1 0, 0i im m 0S
1, 0im
1, 1im
1i 0, 1 1, 1i im m 1, 1 0, 0i im m
2S
-
EE4650: , Instructor: Prof. , [email protected]
HammingDistance Receive
HammingDistanceHammingDistance HammingDistance
10011 01011HammingDistance=2101101110110HammingDistance=4
-
EE4650: , Instructor: Prof. , [email protected]
StateTransitionTableInputBit
m1PresentState
(m0,m1)
EncoderInput
(m1,m0,m1)
Output(n1,n2,n3)
NextState
(m1,m0)0 S0 000 000 S0
1 S0 100 101 S2
0 S1 001 111 S0
1 S1 101 010 S2
0 S2 010 110 S1
1 S2 110 011 S3
0 S3 011 001 S1
1 S3 111 100 S3
-
EE4650: , Instructor: Prof. , [email protected]
Viterbi Decoder Hammingdistance
(accumulatederrormetric) accumulatederrormetric
hammingdistance42+2
-
EE4650: , Instructor: Prof. , [email protected]
Viterbi Decoder [101110010011100][110110010011100]
(101>110)101Viterbidecoderinformationbits10 1 1 1
-
EE4650: , Instructor: Prof. , [email protected]
Traceback Depth
Dtrellisdiagramtracebackbittraceback depth=D
5LViterbi algorithmtraceback depth
-
EE4650: , Instructor: Prof. , [email protected]
VIUSRP
(1)Channel_Coding.vi (2)ConvolutionEncoder
pBernouli noise
ConvolutionEncoder
-
EE4650: , Instructor: Prof. , [email protected]
Channelcodec
-
EE4650: , Instructor: Prof. , [email protected]
1
2
3
100 100 011 000 44 30011 100 101 000 34 50110 000 010 000 60 20
GG G
G
= = =
Convolutional CodecPracticeExample
Encoder:(3,2,4)
Generatormatrix: