Microsoft Word - 104705-06-0909 IJECS-IJENS

104705-06-0909 IJECS-IJENS © December 2010 IJENS I J E N S Abstract—Frequency shift keying (FSK) systems enjoy the highest power efficiencies among the available modulation schemes but are accompanied by the lowest bandwidth (BW) efficiencies. Additional receiver complexities arise due to accurate phase estimations required for a large number of carrier frequencies in phase-coherent synchronous receivers, a problem that can be alleviated by the use of noncoherent detection. We propose a scheme of using M-ary FSK (MFSK) systems with orthogonal envelopes of the RF pulses to improve BW efficiency of MFSK modulation. Hilbert transform (HT) based RF pulse pairs are used in an otherwise MFSK system for the proposed orthogonal pulse MFSK (OP-MFSK) system and continuous time (CT) analysis is performed using noncoherent detection for a single user in an additive white Gaussian noise (AWGN) channel to obtain performance figures.