A FREQUENCY-HOPPING SIMULATOR FOR MULTIPA TH MOBILE CHANNELS

Multipath, jamming, listening and detection are the main limitations f or mobile radio communications. Spread spectrum techniques, especially frequency hopping, can be used to avoid these problems. Therefore, a wideband simulation for multipath mobile channels appeared the most ap propriate evaluation technique. It also gives useful indications for s ystem characteristic improvements. This paper presents the design and realization of a new UHF-VHF propagation simulator. This frequency hop ping simulator (up to 100 000 hops per second) is wideband (10 MHz) th us capable to deal with spread spectrum signals. As it generates up to 16 paths, it can be used in almost all mobile radio propagation situa tions. Moreover, it is also able to simulate high mobile relative spee ds such as air-air communication systems. This simulator can reproduce , in laboratory, 16 rays Rician or Rayleigh fading channels with a max imum time delay of about 15 ms. At the highest frequency of 1 200 MHz, Doppler rates up 2 kHz can be generated corresponding to vehicule spe eds up to 2 000 km/h. Simulation results were derived in various situa tions especially in terrestrial urban and suburban environments, where they could be compared with measurements.