An equalizer and memory mapping predistorter for nonlinearly amplified signals transmitted by coded OFDM systems in multipath fading channel
- Publication Type:
- Journal Article
- Citation:
- Wireless Personal Communications, 2003, 25 (2), pp. 101 - 115
- Issue Date:
- 2003-05-01
Closed Access
| Filename | Description | Size | |||
|---|---|---|---|---|---|
 | 2003000291.pdf | 1.28 MB |
Copyright Clearance Process
- Recently Added
- In Progress
- Closed Access
This item is closed access and not available.
We present an improved channel equalizing scheme to be used in Coded OFDM systems over an ISI channel. The scheme uses Turbo Trellis Coded Modulation (TTCM) which retains a powerful error correction capability while elegantly incorporating turbo coding into the Trellis Coded Modulation (TCM). In OFDM over wireless communications, M-ary Quadrature Amplitude Modulation (M-QAM) schemes have been widely used to achieve high bandwidth efficiency. However, M-QAM signals require linear amplification to avoid spectral regrowth and severe performance degradation due to their large envelope fluctuations. Moreover, the OFDM transmitter shapes the signal with a linear pulse shaping filter. The combination of a linear filter with a High Power Amplifier (HPA) forms a nonlinear system with memory, which severely degrades performance. We propose an efficient one-tap-equalizer using a modified LMS algorithm and a novel adaptive predistortion technique to compensate for the nonlinear distortion caused by the high power amplifier cascaded with a linear filter in TTCM-OFDM systems. The performance of this method is compared with methods that have been used previously with OFDM. A computer simulation confirms that the proposed approach is superior to the conventional methods.
Please use this identifier to cite or link to this item: