Telemetry Channel Capacity Assessment for Reentry Vehicles in Plasma Sheath Environment**supported by the National Program on Key Basic Research Project of China (No. 2014CB340205) and National Natural Science Foundation of China (Nos. 61301173 and 61473228)

Abstract

Channel capacity is the prerequisite and basis for the design of a communication system. To assess the impact of a harsh plasma environment on the communication system of reentry vehicles, Shannon's information theory is used to evaluate the channel capacity through the estimation results of the signal-to-noise ratio obtained by the communication link budget method. First, the attenuation caused by the plasma sheath is calculated with a stratified medium finite-difference time-domain method for typical S, C and Ka telemetry frequencies in a typical reentry plasma environment. Thereafter, typical telemetry transceiver parameters are considered to estimate the channel capacity. Results show that the S-band channel capacity is almost zero at the altitude of 30–40 km and the plasma attenuation at the C-band is slightly better. However, the blackout phenomenon remains obvious. The Ka-band signal can penetrate the plasma sheath layer with the smallest attenuation, thus significantly increasing the capacity of the channel and it may thus adequately meet telemetry needs.