adaptive coding and modulation performance over nonlinear mobile satellite channels

Mobile satellite communication experiences various channel state conditions. these channel impairments degrade overall system reliability and bandwidth efficiency. dynamic link adaptation considers channel variations and adapts the transmission parameters respectively. this paper investigates link adaptation in mobile satellite communications through adaptive coding and modulation scheme. average spectral efficiency improvement has been obtained by adaptation algorithms while the error probability constraints are met. to further extend our scenario in real world satellite systems, power amplifier nonlinearity is taken into account. power amplifier nonlinear performance introduces distortion and signal to noise ratio (snr) degradation. hence, an optimized adapting procedure is proposed to overcome the resulting impairments. moreover, propagation delay in satellite links are significantly large which outdates the channel state information (csi) used for link adaptation decision. channel states and fading conditions would change considerably in this long round trip time, especially in mobile user scenario. as a result, deploying a prediction method to predict time varying channel for reliable modulation and coding selection is required. the accuracy and performance of physical layer adaptation were improved by implementing channel power prediction, mitigating large round trip time and fast channel variations. results indicate satisfactory link availability even in severe shadowing states of the channel.