Reed-Muller codes in error correction in wireless adhoc networks

Abstract

The IEEE 802.11a standard uses a coded orthogonal frequency division multi-plexing (COFDM) scheme in the 5-GHz band to support data rates up to 54 Mbps. The COFDM was chosen because of its robustness to multipath fading affects. In the stan-dard, convolutional codes are used for error correction. This thesis examines the perform-ance of the COFDM system with variable rate Reed-Muller (RM) error correction codes with a goal to reduce the peak-to-average power ratio (PAPR). Contrary to the expecta-tions, RM codes did not provide expected improvement in PAPR reduction. Peak clip-ping and Hanning windowing techniques were investigated in order to reduce the PAPR. The results indicate that a tradeoff exists between the PAPR and the bit-error rate (BER) performance. Although peak clipping yielded considerable reduction in PAPR, it required high signal-to-noise ratios. On the other hand, Hanning windowing provided only a small reduction in PAPR with reasonable BER performance.