A Novel Non-stationary Plasma Sheath Channel Estimation and Distortion Cancellation Method

A new method of distortion cancellation based on channel estimation and equalization is proposed to alleviate the parasitic modulation effect of the non-stationary plasma sheath channel (PSC) on communication signals effectively. This method insert the pilot data into direct sequence spreading telemetry signals and then a novel non-stationary stochastic gradient recursive minimum mean square error (NSGR-MMSE) estimation algorithm is adopted to estimate channel states and equalize the received data at the receiving end. Different from existing mitigation strategies based on reflected signals, the main strategy in this paper is to use practical transmitted signals to mitigate the parasitic modulation effect. The proposed strategy reduces the impact of time delay and improves real-time performance. Compared with traditional minimum mean square error (MMSE) algorithm, the proposed new algorithm only needs a small amount of matrix inverse versus traditional MMSE algorithm, which reduces the computation complexity. Simulation results show that the proposed channel estimation and equalization method can improve the BER performance by three to four orders of magnitude. Moreover, the proposed NSGR-MMSE channel estimation algorithm improves the bit error rate (BER) performance about 1-2dB over the existing MMSE algorithm in the non-stationary plasma sheath channel environment.