1. Wireless Mobile Communication and Transmission Lab. Chapter 8 Application of Error Control Coding

2. Wireless Mobile Communication and Transmission Lab. 2/36 Outline  History ： 2G ——3G——4G  ECC Application For 3G  Adaptive Modulation and Coding (AMC)

3. Wireless Mobile Communication and Transmission Lab. 3/36 Outline  History ： 2G ——3G——4G  ECC Application For 3G  Adaptive Modulation and Coding (AMC)

4. Wireless Mobile Communication and Transmission Lab. 4/36 History

5. Wireless Mobile Communication and Transmission Lab. 5/36 Outline  History ： 2G ——3G （ IMT-2000 ） —— B3G （ IMT-A ） ——4G  ECC Application For 3G  Adaptive Modulation and Coding (AMC)

6. Wireless Mobile Communication and Transmission Lab. 6/36 Error Coding  3G——IMT-2000: 1 、 WCDMA 2 、 CDMA2000 3 、 TD-SCDMA 4 、 WiMAX

7. Wireless Mobile Communication and Transmission Lab. 7/36 WCDMA Usage of channel coding scheme and coding rate

8. Wireless Mobile Communication and Transmission Lab. 8/36 WCDMA Convolutional coding Structure of (2,1,8)

9. Wireless Mobile Communication and Transmission Lab. 9/36 WCDMA Convolutional coding :Structure of (3,1,8)

10. Wireless Mobile Communication and Transmission Lab. 10/36 WCDMA Structure of rate 1/3 Turbo coder (dotted lines apply for trellis termination only)

11. Wireless Mobile Communication and Transmission Lab. 11/36 CDMA2000 Convolutional coding :Structure of(2,1,8) and (3,1,8)

12. Wireless Mobile Communication and Transmission Lab. 12/36 CDMA2000 Convolutional coding :Structure of (4,1,8)

13. Wireless Mobile Communication and Transmission Lab. 13/36 CDMA2000 : Turbo coding

14. Wireless Mobile Communication and Transmission Lab. 14/36 TD-SCDMA Usage of channel coding scheme and coding rate

15. Wireless Mobile Communication and Transmission Lab. 15/36 TD-SCDMA Convolutional coding (2,1,8) and (3,1,8)

16. Wireless Mobile Communication and Transmission Lab. 16/36 TD-SCDMA :Turbo

17. Wireless Mobile Communication and Transmission Lab. 17/36 Outline  History ： 2G ——3G——4G  ECC Application For 3G  Adaptive Modulation and Coding (AMC)

18. Wireless Mobile Communication and Transmission Lab. 18/36 AMC: Adaptive Modulation and Coding  Adaptive Modulation and Coding (AMC) is an alternative link adaptation method in 3G mobile wireless communication. AMC provides the flexibility to match the modulation-coding scheme to the average channel conditions for each user. With AMC, the power of the transmitted signal is held constant over a frame interval, and the modulation and coding format is changed to match the current received signal quality or channel conditions.

19. Wireless Mobile Communication and Transmission Lab. 19/36 “Adaptive” --- A Concept  What is adaptive?  Why adaptive?  Nonadaptive: worst-case channel conditions, inefficient utilization of the channel.  Adaptive: increase average throughput, reduce required transmit power, sufficient use of the channel capacity  How to adaptive?  favorable channel conditions : higher data rates or lower power  channel degrades : reducing the data rate or increasing power

20. Wireless Mobile Communication and Transmission Lab. 20/36 Introduction  First proposed by J. F. Hayes in 1968 “Adaptive feedback communications”, IEEE Trans. Commun. Technol. Vol. 16, Issue 1, pp. 29-34  Hardware constraint  Lack of good channel estimation techniques  Point-to-point radio links without feedback  Has already been used in cellular systems  GSM,EDGE,GPRS,cdma2000,WCDMA etc.

21. Wireless Mobile Communication and Transmission Lab. 21/36 Introduction  Main idea of adaptive transmission: transmission schemes are adapted according to the estimated channel condition that sent back to the transmitter

22. Wireless Mobile Communication and Transmission Lab. 22/36 Introduction  Purpose:  Maintain an acceptable bit error rate (transmission quality)  Make a more efficient use of the channel capacity

23. Wireless Mobile Communication and Transmission Lab. 23/36 Introduction  Several practical constraints:  Channel estimation Fast, slow P r /P t d=vt PrPr PtPt v Very slow Slow Fast

24. Wireless Mobile Communication and Transmission Lab. 24/36 Introduction  Several practical constraints:  Channel estimation Fast, slow  Feed back delay voice or video  Hardware constraints how often the transmitter can change its rate and/or power

25. Wireless Mobile Communication and Transmission Lab. 25/36 Some definitions : instantaneous received signal-to-noise ratio :average received SNR : fading distribution of : transmit power : average transmit signal power : the number of points in each signal constellation

26. Wireless Mobile Communication and Transmission Lab. 26/36 System Model

27. Wireless Mobile Communication and Transmission Lab. 27/36 System Model  Transmission parameters that can be adapted (according to ):  data rate (constellation size) data rate (constellation size)  Coding rate  error probability error probability  transmitted power transmitted power or any combination of these parametersany combination of these parameters

28. Wireless Mobile Communication and Transmission Lab. 28/36 Variable Coding Techniques  Different channel codes are used to provide different coding gain to the transmitted bits.  particularly useful when modulation fixed  For example: is small A stronger error correction code is large A weaker code or no coding

29. Wireless Mobile Communication and Transmission Lab. 29/36 Variable Coding Techniques  Constraints:  Channel remain roughly constant over the block length of constraint length of the code  Implementation:  Multiplexing codes with different error correction capabilities  RCPC codes (Rate-compatible punctured convolution codes)

30. Wireless Mobile Communication and Transmission Lab. 30/36 Examples  HSDPA

31. Wireless Mobile Communication and Transmission Lab. 31/36 Our Work---AMC with LDPC Codes  The BER-CSNR relationship of LDPC codes  For a target BER  and are all constants

32. Wireless Mobile Communication and Transmission Lab. 32/36 Simulation results  Simulation parameters n Code Rate Information Bits Modulation Scheme Spectral Efficiency 1234512345 1/2 2/3 3/4 4/5 5/6 252 504 756 1008 1260 4-QAM 8-QAM 16-QAM 32-QAM 64-QAM 1234512345

33. Wireless Mobile Communication and Transmission Lab. 33/36 Simulation results  threshold selection according to performances of individual schemes under AWGN channel (target BER=10 -4 )

34. Wireless Mobile Communication and Transmission Lab. 34/36 Simulation results  Performance of adaptive and non-adaptive LDPC codes under Rican fading channel (K=5,assuming ideal channel estimation)

35. Wireless Mobile Communication and Transmission Lab. 35/36 Simulation results  BER performance of adaptive LDPC under constant channel estimation error (CEE)

36. Wireless Mobile Communication and Transmission Lab. 36/36 Simulation results  Spectral efficiency of adaptive LDPC codes under Rican fading channel under different channel estimation error