A noncoherent, bandwidth-efficient modulation

scheme is proposed for frequency-hopping multiple-access

(FH-MA) networks. The proposed scheme is a combination

of noncoherent -ary amplitude-shift keying (NMASK) and

orthogonal frequency-division multiplexing (OFDM). Using

this scheme will minimize the required data bandwidth. The

number of frequency slots available to the users will increase

significantly for a fixed spread-spectrum bandwidth (BW55).

The effect of the multiple-access interference will be reduced.

Simple and accurate bit error rate expressions have been derived

for FH-OFDM-MASK in additive white Gaussian noise channels

and for FH-OFDM-ASK in Rayleigh fading channels.

Index Terms—Amplitude-shift keying (ASK), frequency hopping

(FH), -ary amplitude-shift keying (MASK), noncoherent,

orthogonal frequency-division multiplexing (OFDM), Rayleigh

channels.