ADAPTIVE MODULATION SYSTEM WITH PUNCTURED CONVOLUTIONAL CODE FOR HIGH-QUALITY PERSONAL COMMUNICATION-SYSTEMS

This paper proposes an adaptive modulation system with a punctured con volutional code for land mobile communications to achieve high quality , high bit rate, and high spectral efficient data transmission in mult ipath fading environments. The proposed system adaptively controls the coding rate of the punctured convolutional code, symbol rate, and mod ulation level according to the instantaneous fading channel conditions . During good channel conditions, the modulation parameters are select ed to increase the transmission rate as much as possible with satisfyi ng a certain transmission quality. As channel conditions become worse, lower rate modulation parameters are applied or transmission is stopp ed. The performances in fading environments are evaluated theoreticall y and by computer simulations. The results show that the proposed syst em can realize higher quality transmission without the degradation in average bit rate compared to conventional adaptive modulation systems.