Performance of frequency-hopped NPCSMA for broad-band personalcommunication services (B-PCS) at millimeter waves in an urban mobileradio environment

摘要

A millimeter-wave (MMW) propagation model, based on multiraynoptical theory and the geometrical theory of diffraction (GTD), is usednto statistically study the delay spread and coherence bandwidth (Bcn) for broad-band personal communication services (B-PCSs) in urbannmobile radio environments. The results of the statistical model arencompared with outdoor measurements near the street level with Bcn varying over a range of frequencies (14-100 MHz). It is shownnthat the distribution of Bc depends on antenna heights,nstreet layout, and frequency. The signal level statistics are evaluatednand found to agree with the measurements. In general, these statisticsnare non-Rayleigh distributed. The additive thermal Gaussian noise (AGN)nis calculated for such channels to evaluate the signal-to noise ration(SNR). The performance of the medium-access control (MAC) sublayer isnstudied by first evaluating the probability of packet retransmission andnthen the performance of the FH-NPCSPMA protocol. The FH-NPCSMA protocolnis the combination of frequency hopping spread spectrum (FH-SS) andnnonpersistent carrier-sense multiple access (NPCSMA) that is proposed tonimprove the system throughput and average packet delay for both highntraffic and multipath channels at MMW. The main advantage of thenPH-NPCSMA protocol is to improve the performance over fading channels