1. Low-Density Parity-Check Codes
Speaker : 詹承洲
Advisor : Prof. Andy Wu
Date : 2007/03/07

2. Outline Introduction to LDPC Codes Problem Statement
What You Will Learn
Expected Results
Reference

3. Communication
Channel
Noise

4. Digital Communication Systemrb rc
JPEG, MPEG
LDPC codes
BPSK, QPSK,
16-QAM, 64-QAM
Transmitter
Modulator
Channel
Encoder
Source
Information rs
Channel
Demodu-
lator
Channel
Decoder
Source
Data Sink
Receiver

5. Motivation LDPC codes were first introduced by Gallager in 1962
LDPC codes was rediscovered by MacKay in 1993:
Excellent error-correcting performance near the Shannon limit
BER
LDPC codes
Only 0.045dB gap
SNR(dB)

6. Applications WiMAX system IEEE 802.11n NSC 3C IT Project
NTU/MTK Project

7. Introduction to LDPC Codes
Parity check matrix : sparse matrix
Bipartite graph B1 B2 B3 B4 B5 B6 B7 B8 B9 C1 C2 C3 C4 C5 C6
Bit nodes
(columns) B1 B2 B3 B4 B5 B6 B7 B8 B9
Check nodes
(rows) C1 C2 C3 C4 C5 C6

8. Our Achievement JSSC’02–(1024, 512)--52.5mm2 Our chip for WiMAX system

9. Problem Statement Algorithm domain: Architecture domain :
Complex operation of VNU and CNU
Low hardware utilization efficiency
Inefficient termination scheme
Architecture domain :
Large area cost
Need some high throughput approaches
High power consumption

10. What You Will Learn Concept of channel coding
The most powerful channel coding till now – LDPC
Fixed-point analysis
Evaluation of the performance of a channel coding

11. Expected Results Paper survey and acquaintance with LDPC codes
C model of LDPC codes
Advanced schedule
Algorithm domain
Operation function
Termination Scheme
Architecture domain
Critical path shortening

12. Background Needed Linear algebra C programming Matlab (Optional)
DSP or Communication Systems (Optional)

13. Reference
[1] Xiao-Yu Hu, Eleftheriou E.; Arnold D.-M., Dholakia A., “Efficient Implementations of the Sum-Product Algorithm for Decoding LDPC Codes,” Global Telecommunications Conference, Vol. 2, pp.1036 –
1036E, Nov. 2001