PROPAGATION HANDBOOK FOR WIRELESS COMMUNICATION SYSTEM DESIGN
CHAPTER ONE PROPAGATION PHENOMENA AFFECTING WIRELESS SYSTEMS 1 CHAPTER TWO PROPAGATION FUNDAMENTALS 101 CHAPTER THREE ABSORPTION 135 CHAPTER FOUR REFRACTION 169 CHAPTER FIVE ATTENUATION BY CLOUDS AND RAIN 225 CONTENTS CHAPTER ONE PROPAGATION PHENOMENA AFFECTING WIRELESS SYSTEMS 1 1 TYPES OF SYSTEMS THE PHRASE WIRELESS SYSTEM REFERS TO ANY SYSTEM THAT USES ELECTROMAGNETIC WAVES TO TRANSFER INFORMATION FROM ONE LOCATION TO ANOTHER WITHOUT USING WIRES THE APPLICATIONS CAN INCLUDE TRANSMITTING VOICE BETWEEN HAND HELD WALKIE TALKIES TRANSMITTING DATA FROM A SATELLITE TO GROUND OR FROM ONE COMPUTER TO ANOTHER WITHIN A ROOM OR USING RADAR TO SENSE RAIN THIS HAND BOOK CONSIDERS ONLY THE PROPAGATION OF ELECTROMAGNETIC WAVES IN THE MICRO WAVE THROUGH MILLIMETER WAVE RADIO FREQUENCY SPECTRUM 0 3 THROUGH 300 GIGAHERTZ GHZ THESE FREQUENCIES LIE IN THE ULTRA HIGH UHF 0 3 TO 3 GHZ SUPER HIGH SHF 3 TO 30 GHZ AND EXTRA HIGH EHF 30 TO 300 GHZ COM MUNICATION BANDS FREQUENCY BANDS ARE OFTEN REFERENCED BY THEIR RADAR BAND DESIGNATIONS AS SHOWN IN TABLE 1 1 ACTUAL BAND IDENTI CATION IS OFTEN LESS PRECISE THAN THAT INDICATED IN THE TABLE FOR XED SATELLITE COMMUNICATION SERVICES KA BAND REFERS TO THE 20 TO 30 GHZ FREQUENCY RANGE THIS HANDBOOK FOCUSES ON TRANSMISSION IN AND THROUGH THE LOWER ATMO SPHERE THE REGION OF THE ATMOSPHERE WHERE WEATHER PHENOMENA OCCUR THE PROPERTIES OF THE LOWER ATMOSPHERE ARE HIGHLY VARIABLE AND CHANGE HOURLY DAILY MONTHLY AND YEARLY THEIR EFFECTS ON RADIO WAVE PROPAGATION PRODUCE RANDOM VARIATIONS IN THE AMPLITUDE PHASE FREQUENCY POLARIZATION COHER ENCE BANDWIDTH DELAY SPREAD AND PROPAGATION DIRECTION OF THE ELECTROMAG NETIC WAVES KNOWLEDGE OF THE STATISTICS OF ONE OR MORE OF THESE EFFECTS MAY BE NECESSARY FOR SYSTEM DESIGN A WIRELESS SYSTEM OF CONSIDERABLE INTEREST IS THE CELLULAR SYSTEM FOR THIS SYSTEM THE DOMAIN OF INTEREST IS SUBDIVIDED INTO A NUMBER OF SMALLER CELLS WITH TRANSMITTERS AND RECEIVERS THAT HANDLE COMMUNICATIONS WITHIN EACH CELL OR COMPLEX OF CELLS THE ORGANIZATION AND STRUCTURE OF A CELLULAR SYSTEM ARE NOT CONSIDERED IN THIS HANDBOOK BUT THE STATISTICS OF THE PROPERTIES OF A TRANSMISSION CHANNEL BETWEEN A TRANSMITTER AND RECEIVER IN A CELL AND THE JOINT STATISTICS FOR MULTIPLE TRANSMISSION PATHS WITHIN A CELL OR BETWEEN CELLS 1 ARE THE CONTEXT IS THE STATISTICS FOR A SINGLE PATH AND THE JOINT STATISTICS FOR MULTIPLE PATHS MUCH PROPAGATION DATA HAS BEEN COLLECTED FOR USE IN THE DESIGN OF XED SERVICE SATELLITE AND TERRESTRIAL COMMUNICATION SYSTEMS FIXED SERVICE MEANS A COMMUNICATION SYSTEM EMPLOYING XED TERMINALS ON THE EARTH S SURFACE FOR SATELLITE SYSTEMS THE SATELLITE CAN BE IN GEOSTATIONARY ORBIT OR IN ANY OTHER ORBIT THAT PRODUCES A VARIATION IN THE POINTING DIRECTION FROM THE XED GROUND STATION TO THE SATELLITE CONSIDERABLE DATA HAS ALSO BEEN COLLECTED FOR CELLULAR SYSTEMS AND MOBILE SATELLITE SYSTEMS PUBLISHED ANNUAL ATTENUATION STATISTICS ARE AVAILABLE FROM MANY LOCATIONS IN EUROPE AND NORTH AMERICA SOME DATA ARE AVAILABLE FROM OTHER LOCATIONS TOO STUDY GROUP 3 OF THE RADIOCOMMUNICATION STUDY GROUPS OF THE INTERNATIONAL TELECOMMUNICA TIONS UNION ITU R PROVIDES DATA BANKS FOR MODEL DEVELOPMENT AND VERI CATION AND FOR USE IN SYSTEM DESIGN 1 THE EMPIRICAL STATISTICS IN THE DATA BANKS FOR XED SERVICE SYSTEMS ARE GENERALLY FOR OBSERVATIONS OF LIMITED DURATION THAT IS FROM RECORDS THAT SPAN ONLY 1 TO 5 YEARS THE DATA COLLECTED FOR MOBILE SERVICE SYSTEMS ARE MORE LIMITED MODELS THAT SUMMARIZE THE DATA IN THE DATA BANKS WILL PROVIDE A BETTER ESTIMATE OF THE EXPECTED STATISTICS FOR A PARTICULAR PATH THAN THE EMPIRICAL RESULTS FROM MEASUREMENTS OF LIMITED DURATION ON THAT PATH POINT TO MULTIPOINT XED LINE OF SIGHT TERRESTRIAL SYSTEMS ARE NOW IN DEVELOPMENT USING FREQUENCIES IN THE EHF BAND LONG DURATION EMPIRICAL STATISTICS ARE NOT AVAILABLE AT FREQUENCIES ABOVE 30 GHZ FOR SINGLE PATHS OR JOINT STATISTICS FOR TWO OR MORE PATHS ORIGINATING FROM A SINGLE POINT PHYSICAL PROPAGATION MODELS ARE REQUIRED TO EXTEND PREDICTIONS TO LOCATIONS OR CON DITIONS WHERE ADEQUATE OBSERVATIONS ARE NOT AVAILABLE THESE MODELS CAN BE VALIDATED USING DATA FROM AVAILABLE DATA BANKS THE EXTRAPOLATION OF EMPIR ICAL CURVE TTING OR REGRESSION MODELS IS NOT RECOMMENDED THIS HANDBOOK DESCRIBES PHYSICAL PROPAGATION MODELS FOR THE PREDICTION OF STATISTICS FOR A WIDE VARIETY OF COMMUNICATION BROADCAST NAVIGATION RADAR AND REMOTE SENSING SYSTEMS OPERATING IN THE UHF SHF AND EHF TABLE 1 1 FREQUENCY BAND NOMENCLATURES RADAR BAND LOWEST FREQUENCY GHZ HIGHEST FREQUENCY GHZ COMMUNICATION BAND UHF 0 3 1 UHF L 1 2 UHF S 2 4 UHF SHF C 4 8 SHF X 8 12 SHF KU 12 18 SHF K 18 27 SHF KA 27 40 SHF EHF V 40 75 EHF W 75 110 EHF MM 110 300 EHF 2 PROPAGATION HANDBOOK FOR WIRELESS COMMUNICATION FREQUENCY BANDS THE MODELS ARE DEVELOPED FROM METEORO LOGICAL DATA AND DEPEND ON THE AVAILABILITY OF CLIMATE DATA THE MODELS WERE VALIDATED OVER LIMITED RANGES BY COMPARING WITH AVAILABLE DATA ERROR STA TISTICS ARE PRESENTED FOR EACH MODEL WHERE POSSIBLE THE EXPECTED INTERAN NUAL VARIABILITY OF THE PREDICTIONS IS PRESENTED TO ESTABLISH THE RISK ASSOCIATED WITH A PREDICTION THE EXPECTED PREDICTION UNCERTAINTY IS USED WHEN COM PARING PREDICTIONS TO EMPIRICAL STATISTICS 1 2 DESIGN CRITERIA COMMUNICATION SYSTEMS ARE DESIGNED TO SPECI C AVAILABILITY REQUIREMENTS FOR THE SIMPLEST TRANSMISSION PATH BETWEEN A SINGLE TRANSMITTING ANTENNA AND A SINGLE RECEIVING ANTENNA THE AMPLITUDE OF THE RECEIVED SIGNAL RELATIVE TO THE UNWANTED NOISE IN THE RECEIVER MAY BE THE STATISTIC OF INTEREST IF THE RECEIVED SIGNAL LEVEL IS TOO LOW THE SIGNAL MAY NOT BE DETECTED IN THE NOISE IF TOO HIGH NONLINEAR RECEIVER EFFECTS MAY DISTORT THE SIGNAL AND RENDER IT UNINTELLIGIBLE THE ERROR RATE FOR A DIGITAL COMMUNICATION LINK DEPENDS ON THE SIGNAL TO NOISE RATIO AS WELL AS OTHER FACTORS THE STATISTICS OF THE SIG NAL TO NOISE RATIO ARE THEREFORE IMPORTANT THE SIGNAL TO NOISE RATIO DEPENDS ON THE RECEIVER DESIGN THE GAINS AND LOSSES OF THE TRANSMITTING AND RECEIVING ANTENNAS THE MODULATION AND CODING OF THE TRANSMITTED SIGNAL THE TRANS MITTED SIGNAL POWER THE PATH LOSS BETWEEN THE ANTENNAS AND THE POSSIBILITY OF INTERFERENCE FROM OTHER TRANSMITTERS AVAILABILITY IS THE FRACTION OF TIME THAT THE COMMUNICATION LINK IS AVAILABLE FOR USE WITH A SIGNAL TO NOISE THAT EXCEEDS THE DESIGN SPECI CATION FOR A GIVEN ERROR PERFORMANCE THE OUTAGE TIME IS THE FRACTION OF TIME FOR WHICH THE DESIRED ERROR PERFORMANCE IS NOT OBTAINED THE ATMOSPHERE MAY AFFECT THE PERFORMANCES OF THE ANTENNAS AND TRANS MISSION PATH FIGURE 1 1 AT FREQUENCIES ABOVE 10 GHZ AND DEPENDING ON ANTENNA DESIGN RAINWATER OR WET SNOW ON AN ANTENNA MAY REDUCE THE MAG NITUDE OF THE RECEIVED SIGNAL INCREASE THE PATH LOSS THE GEOMETRIC SPREAD ING OF THE ELECTROMAGNETIC ENERGY TRANSMITTED BY THE ANTENNA PRODUCES A CHANGE IN SIGNAL STRENGTH WITH DISTANCE ALONG THE PATH TO THE RECEIVING ANTENNA WATER VAPOR AND OXYGEN IN THE ATMOSPHERE MAY CAUSE SIGNAL ABSORPTION ON THE PATH PRODUCING A LOSS OR ATTENUATION RELATIVE TO THE GEO METRIC SPREADING SCATTERING BY CLOUDS AND RAIN PRODUCE AN EXCESS ATTENUA TION RELATIVE TO THE GEOMETRICAL SPREADING AND GASEOUS ABSORPTION FOR A PARTICULAR PATH THE TOTAL ATTENUATION GASEOUS ABSORPTION PLUS EXCESS ATTEN UATION CHANGES WITH TIME AS CLOUDS AND RAIN DRIFT ACROSS THE PATH AND TEMPERATURE AND HUMIDITY CHANGE ALONG THE PATH THE STATISTICS OF CHANGING PATH LOSS MAY THEREFORE BE IMPORTANT IN THE DESIGN OF A SYSTEM DEPENDING ON CARRIER FREQUENCY AND PATH LENGTH THROUGH THE ATMOSPHERE THE TOTAL ATTENUATION STATISTICS MAY CONSTRAIN SYSTEM DESIGN TIME SERIES OF ATTENUATION OBSERVATIONS AT TWO KA BAND FREQUENCIES ON AN EARTH SPACE PATH FOR A SINGLE DAY WITH RAIN IS PRESENTED IN FIGURE 1 2 THE BEACON TRANSMITTERS WERE ON THE NASA ACTS THE RECEIVER WAS LOCATED IN 3 PROPAGATION HANDBOOK FOR WIRELESS