LTE Transport Channel Processing Impl
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Transcript of LTE Transport Channel Processing Impl
Transport Channel Processing
Introduction
Introduction
Transport Channel Processing
› Encoding
› Modulation techniques
› Scrambling?
eNBeNB
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?) ?Radio Channel
Transport Block
Scope and objectives
› Error correction and error protection
› Scrambling codes in LTE
› Modulation
› Describe LTE physical layer processing
› Explain the principle of error correction
› Describe CRC and FEC coding
› Explain the problem of multipath propagation
› Describe the use of scrambling in LTE
› Describe the use of modulation
Objectives
Scope
> Pre-testPre-test
PROPERTIES
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> OverviewOverview
Transport Channel Processing
› CRC– Error Detection
› FEC– Error Correction
› Modulation
MUX
D
P1
P2
Turbo Encoder
Encoder #1
Encoder #2
Interleaver
Data
Checksum 24 bitsOriginal Data
x bits
CRC Generator
Original Data x bits
Transport Channel Processing
Physical layer processing
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
Transport Block
Cellular Error Correction
Digital Cellular
Analog Cellular
Transmitted Signal Received Signal + Noise
Transmitted Signal Received Signal + Noise
EM
5 Main Street
Littletown
Eddie McConnell
5 Main Street
Littletown LT1701
Digital Cellular Error Correction
With minimal data...Errors are uncorrectable
With redundant data...Errors are correctable
CRC Coding
Checksum 24 bits110010…110011
Original Data
x bits
CRC Generator
Original Data 1001011010…
CRC Generator
Re-Generated Checksum 110010…110001
Transmitter
Receiver
If Checksums do not match, there exists at least one error
Received Data 1001010010…
Received Checksum
110010…110011
RF Transmission Path
PROPERTIES
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FEC Coding
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
Transport Block
FEC Coding Approaches
Block Codes Ex. transmit “New York City” to represent ‘NYC’
Continuous Codes Data processed continuously through FEC Built-in redundancy correct bit errors LTE uses Turbo codes
PROPERTIES
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Continous Codes
Original Data 00011011...
FEC Generator
FEC Encoded data 1010011100110110...
Original Data 00011011
Decoder
Transmitter
Receiver
RF Transmission Path
Multipath Propagation
Time-delayed replicas
Varying signal power Burst errors
PROPERTIES
On passing, 'Finish' button: Goes to Next SlideOn failing, 'Finish' button: Goes to Next SlideAllow user to leave quiz: At any timeUser may view slides after quiz: At any timeUser may attempt quiz: Unlimited times
Turbo Coding
Data
MUX
D
P1
P2
Turbo Encoder
Encoder #1
Encoder #2Interleaver
Turbo Decoder
DecodedData
DE-MUX
D
P1
P2
D
Interleaver
Inte
rleav
er
De-
Inte
rleav
er
Decoder #2
Decoder #1
Parallel, recursive & systematic Detect/correct errors - digital data, different channels
PROPERTIES
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Scrambling in LTE
› Inter cell interference› Cell specific bit-level scrambling› ICIC
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
Modulation
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
Modulation schemes
2 bits/symbol
QPSK
00
11
10
01
4 bits/symbol
16-QAM
1111
6 bits/symbol
64-QAM
111111
OFDM
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
Summary
Summary
Summary
› Cyclic Redundancy Check› Channel coding› Cell specific bit-level
scrambling› Data modulation› OFDM
Coding
Scrambling
Modulation
CRC
Decoding
Descrambling
Demodulation
CRC check
OFDM(IFFT) OFDM(FFT)
Radio Channel
Tx Rx
QUIZ
Quiz
PROPERTIES
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