Performance of frequency-hopped NPCSMA for broad-band personal communication services (B-PCS) at millimeter waves in an urban mobile radio environment

A millimeter-wave (MMW) propagation model, based on multiray optical theory and the geometrical theory of diffraction (GTD), is used to statistically study the delay spread and coherence bandwidth (B/sub c/) for broad-band personal communication services (B-PCSs) in urban mobile radio environments. The results of the statistical model are compared with outdoor measurements near the street level with B/sub c/ varying over a range of frequencies (14-100 MHz). It is shown that the distribution of B/sub c/ depends on antenna heights, street layout, and frequency. The signal level statistics are evaluated and found to agree with the measurements. In general, these statistics are non-Rayleigh distributed. The additive thermal Gaussian noise (AGN) is calculated for such channels to evaluate the signal-to noise ratio (SNR). The performance of the medium-access control (MAC) sublayer is studied by first evaluating the probability of packet retransmission and then the performance of the FH-NPCSPMA protocol. The FH-NPCSMA protocol is the combination of frequency hopping spread spectrum (FH-SS) and nonpersistent carrier-sense multiple access (NPCSMA) that is proposed to improve the system throughput and average packet delay for both high traffic and multipath channels at MMW. The main advantage of the PH-NPCSMA protocol is to improve the performance over fading channels.