Abstract
Adaptive modulation improves the system throughput considerably by matching transmitter parameters to time-varying wireless fading channels. Crucial to adaptive modulation is the quality of channel state information at the transmitter. In this paper, we first present a channel predictor based on pilot symbol assisted modulation for multiple-input multiple-output Rayleigh fading channels. We then analyze the impact of the channel prediction error on the bit error rate performance of a transmit-beamformer with adaptive modulation that treats the predicted channels as perfect. Our numerical results reveal the critical value of the normalized prediction error, below which the predicted channels can be treated as perfect by the adaptive modulator; otherwise, explicit consideration of the channel imperfection must be accounted for at the transmitter.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1285-1294 |
| Number of pages | 10 |
| Journal | IEEE Transactions on Wireless Communications |
| Volume | 3 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jul 2004 |
Bibliographical note
Funding Information:Manuscript received September 17, 2002; revised February 24, 2003. This work was supported in part by the National Science Foundation (NSF) under Grant 0105612 and in part by the ARL/CTA under Grant DAAD19-01-2-011. The material in this paper was presented in part in the International Conference on Acoustics, Speech, and Signal Processing, Hong Kong, April 6–10, 2003. The associate editor coordinating the review of this paper and approving it for publication was Dr. H. Xu.
Keywords
- Adaptive modulation
- Channel prediction
- Multiantenna systems
- Transmit beamforming