A novel unified equalization and demodulation of chaoticdirect sequence spread spectrum signal based on state estimation

Abstract

A novel unified algorithm based on state estimation was proposed for equalization and demodulation of chaotic direct sequence spread spectrum (CD3S) signal through a non-ideal channel. The algorithm uses the state equations of the channel and the CD3S signal, as well as the reciprocal relationship between equalization and demodulation. Multiple extended kalman filters (EKF) were used for equalizing the channel while demodulating the binary message simultaneously by implementing them in reciprocal interaction. This algorithm could not only overcome the impact brought about by non-ideal channel, such as multipath interference and channel noise, but also demodulate the binary message from CD3S signal. This unified approach utilizes the information more adequately and has better real-time performance than independent approaches. Simulation results demonstrated that the proposed algorithm has a fast convergence rate, and is resistant to the multipath effect without knowledge of channel characteristic and the noise, so the efficient and reliable transmission of the CD3S signal through the non-idea channel is realized.