Rec.ITU-RF.1093-11RECOMMENDATIONITU-RF.1093-1*EFFECTSOFMULTIPATHPROPAGATIONONTHEDESIGNANDOPERATIONOFLINE-OF-SIGHTDIGITALRADIO-RELAYSYSTEMS(QuestionITU-R122/9)(1994-1997)Rec.ITU-RF.1093-1TheITURadiocommunicationAssembly,consideringa)thatfadingduetomultipathpropagationmaydistortandattenuatereceivedsignalsonline-of-sightpathsandtherebyimpairtheperformanceofradiosystems;b)thatcountermeasuressuchasdiversityreceptionandadaptiveequalizationareavailabletoreducetheeffectsofmultipathfadingonsystemperformance;c)thatmethodsofpredictingtheeffectsofmultipathfadingontheerrorperformanceofaradiosystemareneededforlinkplanningorforcomparingalternativedesigns,recommends1thatmultipathfadingcountermeasuresbeincorporatedinradiosystemdesign,asneeded,toimproveerrorperformance;2thatthepredictionmethodsdescribedinAnnex1maybeusedforguidanceinradiolinkplanning;3thatthechoiceofdiversityreceptionandadaptiveequalizationforadigitalradio-relaysystemshouldincludetheconsiderationsofAnnex1;alsoRecommendationITU-RF.752“Diversitytechniquesforradio-relaysystems”shouldbetakenintoaccount.ANNEX1Effectsofmultipathpropagationondesignandoperationofline-of-sightdigitalradio-relaysystems1IntroductionThepurposeofthepresentAnnexistofurnishguidanceonpropagation-relatedaspectsofthedesignandoperationofdigitalradio-relaysystems,drawingoninformationfromRadiocommunicationStudyGroup3textsandmeasurementsconductedbyadministrations.ThefirstpartoftheAnnexexplainstheroleofmultipathfadingasthedominantpropagationfactorfordigitalradio-relaysystemsoperatingatfrequenciesbelowabout10GHz.Thefollowingsectionsdiscusstherolesofdiversitytechniquesandadaptiveequalizationinreducingchanneldegradations.Finally,thepredictionofsystemperformancedependingontheforegoingfactorsistreated.MoredetailedinformationontheapplicationoftheguidancecontainedherecanbefoundintheHandbookondigitalradio-relaysystems._______________*ThisRecommendationshouldbebroughttotheattentionofRadiocommunicationStudyGroup3.