SYSC 4607 – Slide Set 17 Outline

1. SYSC 4607 – Slide Set 17 Outline • Review of Previous Lecture • Variable-Rate Variable-Power MQAM • Channel Estimation Error and Delay

2. Review of Previous Lecture • Adaptive modulation varies modulation parameters relative to fading to improve performance • Adaptive Techniques - Variable-Rate - Variable-Power - Variable-Rate Variable-Power

3. Adaptive Coding and Modulation - Requires reliable feedback channel and accurate channel estimation - Increases transmitter and receiver complexity

4. Variable-Rate Variable-Power MQAM

5. Variable-Rate Variable-Power MQAM

6. Formulation of Optimization

7. Formulation of Optimization

8. Optimal Adaptive Scheme

9. Optimal Adaptive Scheme

10. Spectral Efficiency

11. Channel Inversion with Fixed Rate

12. Discrete-Rate Adaptation

13. Constellation Restriction

14. Rate and Power Adaptation (Five Regions)

15. Power Adaptation

16. Average Rate

17. Spectral Efficiency in Rayleigh Fading

18. Update Rate in Adaptive Modulation

19. Channel Estimation Error and Delay

20. Channel Estimation Error and Delay

21. Channel Estimation Error and Delay

22. Channel Estimation Error and Delay

23. Main Points • Adaptive MQAM uses capacity-achieving power and rate adaptation, with power penalty K. • Adaptive MQAM comes within 5-6 dB of capacity • Discretizing the constellation size results in negligible performance loss. • Constellations cannot be updated faster than 10s to 100s of symbol times: OK for most Dopplers. • Estimation error and delay can lead to irreducible error floors.