Adaptive Wavelet Coding Design for a Control System on Wireless Channels
Wireless systems, Channel coding, Wavelet coding, Automation and remote control
The wireless sensor networks (WSN) are constituted by nodes interconnected by wireless channels with sensing and control ability. However, due to the use of wireless communication channels, the information exchanged among the sensor nodes are susceptible to the effects of impulsive noise and fading produced by multipath propagation. In order to minimize the fading effects, channel coding and diversity techniques are often used in wireless systems. Among them, the wavelet coding is a good alternative for the WSN by their robustness to the effects of the wireless channel and by its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level, and evaluate the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus Eb/N0, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. So far, results indicate be feasible to implement an adaptive wavelet coding in this communication scenario.