DIRECTIVE ANTENNA DIVERSITY RECEPTION SCHEME FOR AN ADAPTIVE MODULATION SYSTEM IN HIGH-MOBILITY LAND MOBILE COMMUNICATIONS

This paper proposes a directive antenna diversity reception scheme for an adaptive modulation/time division multiple access (TDMA)/time divi sion duplex (TDD) system to achieve high quality, high bit rate and hi gh spectral efficient data transmission in high mobility land mobile c ommunication environments. In mobile stations, a directive antenna is applied to equivalently reduce the observed variation Speed of the fad ing channel. At each branch, the offset frequency (f(off)) and f(off)- canceled fading variation are estimated to improve accuracy of the pro pagation path characteristics estimation even in high maximum Doppler frequency (f(d)) environments. Computer simulation confirms that the p roposed scheme can achieve successful variable rate transmission in fa st fading environments.