Propagation measurement-based probability of error predictions fordigital land-mobile radio

摘要

This paper demonstrates that closed-form equations can be used toncalculate error rates for Π/4-shift differential quadraturenphase-shift keying (DQPSK) directly from time-series measurements ofnimpulse-response data on frequency-selective land-mobile radio channels.nResults are quantitative and free from uncertainties that can accompanynsuch predictions when they are made using qualitative relationshipsnbased on assumed channel characteristics. Calculations using thendemonstrated method show that significantly greater signal-to-noisenratios are required on macrocellular (MC) channels than those requirednon microcellular (ΜC) channels for the same performance, In addition,nit is shown that MC channels require channel protection, even for IS54nperformance levels, whereas higher data rates (up to 250 kbps atn10-3) and lower error probabilities (down to 10-4nat 48.6 kbps) are possible on line-of-sight (LOS) ΜC channels withoutnsuch protection. This is considered to be crucial information in thendesign of future systems. Through the analysis of quantitative results,nnot available elsewhere, it is shown that correlations between rms delaynspread and performance measures, such as unprotected channel-error-ratenfloors and maximum data rates, are poor. Recommendations are, therefore,nmade regarding other parameters (the Rician K ratio and anothernparameter Vol, defined in the present paper) that can be derived throughnsimple propagation measurements and used to predict these performancencharacteristics with greater assurance