Nonlinearity Compensation Technique for Common Band Satellite Channel

For effective use of frequency band, carrier superposing (common band) technique has been introduced to satellite communication systems. Meanwhile the satellite’s Traveling Wave Tube Amplifier (TWTA) is preferred to be operated near saturation level for power efficiency. However nonlinearity characteristics of TWTA around that level become the cause of interference for carrier superposing systems. Therefore, in this paper, a post compensation technique for TWTA nonlinear distortion is introduced and verified for practical use of carrier superposed Point to Point satellite communication system which adopts interference canceller. Result of the simulation shows it is possible to drastically reduce the BER degradation at all range, specially at nonlinear operating point. This paper also reveals the effect of operating point mismatch that can be caused by rainfall and other environmental changes.