Performance of GTFM in a frequency-selective Rayleigh fading channel

Generalized tamed frequency modulation (GTFM) is a bandwidth-efficient digital modulation technique suitable for use in land mobile radio sytems. The authors examine the influence of both frequency-flat and frequency-selective Rayleigh fading on GTFM with discriminator detection. In addition, the effects of cochannel and adjacent channel interference are considered in the frequency-flat fading channel. Results are presented in the form of bit-error-rate (BER) curves at several vehicle speeds and multipath delay spreads. For frequency-flat fading channels it is shown that the irreducible error rate is proportional to the square of the maximum Doppler frequency normalized to the bit rate. In slow frequency-selective channels the irreducible error rate is found to be proportional to the square of the normalized delay spread. Finaly, the relative insensitivity of the error rate to the shape of the power delay profile is verified for small delay spreads. Simulations also indicated that for small delay spreads (d ≤ 0.2) the BER is not affected by the speed of the clock recovery circuit.