Performance of direct-sequence spread-spectrum multiple-access systems in mobile radio

Analytical techniques and numerical methods were used for a channel having a number of resolvable, discrete Rayleigh fading paths, while simulations were employed for transmissions over urban mobile radio channels. By transmitting a sounding sequence of chip length N _S=511 to allow the receiver to estimate the channel impulse response, spreading the symbol over N=127 chips, and on deploying fifth-order combinative space diversity equipped with adaptive correlation diversity of K _beta =1.0 (CD/ACD), a residual probability of bit error P _R of less than 10 ^-3 for 10 users was obtained, in spite of the urban mobile radio channel having 19 resolvable fading paths. By increasing N to 511 and deploying fifth-order maximal-ratio-combining space diversity, a P _R of 4*10 ^-5 for 20 users was achieved when the radio channel consisted of 10 resolvable independent Rayleigh fading paths.<>