Title :
The impact of delay spread on multilevel FM systems in a Rayleigh fading, CCI and AWGN environment
Author :
Wu, Gene K. ; Feher, Kamilo
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Davis, CA, USA
Abstract :
An experimental study of the impact of delay spread on the performance of 4 PAM-FM mobile systems in a Rayleigh fading, cochannel interference (CCI) and additive white Gaussian noise (AWGN) environment is presented. The increase of the modulation index can improve the BER if the reflected signal power is 10 dB less than the direct signal in the two-ray fading model. A strategy which reduces the impact of delay spread even in the worst case situation is proposed. By increasing the roll-off factor of the lowpass filters and by lowering the modulation index, for a BER of 0.01, the delay spread immunity is increased 300% without the need for adaptive equalization. In the delay spread environment, CCI is not significant if it is less than -20 dB. AWGN interference is noticeable only when it is higher than -13 dB
Keywords :
delays; digital radio systems; fading; frequency modulation; mobile radio systems; pulse amplitude modulation; radiofrequency interference; white noise; 4 PAM-FM mobile systems; AWGN; BER; CCI; Rayleigh fading; additive white Gaussian noise; cochannel interference; delay spread; direct signal; lowpass filters; modulation index; reflected signal power; roll-off factor; two-ray fading model; AWGN; Adaptive filters; Additive white noise; Bit error rate; Delay; Interchannel interference; Modulation; Power system modeling; Radiofrequency interference; Rayleigh channels;
Conference_Titel :
Vehicular Technology Conference, 1992, IEEE 42nd
Conference_Location :
Denver, CO
Print_ISBN :
0-7803-0673-2
DOI :
10.1109/VETEC.1992.245340
