OVER-THE-HORIZON DATA/VIDEO LINKS FOR RURAL AREAS

THIS PROPOSAL INVESTIGATES AN EXTENDED LINE-OF-SIGHT RADIO TECHNIQUE FOR LOW-COST DATA AND VIDEO LINKING OF RURAL ORGANIZATIONS AND PUBLIC INSTITUTIONS. EFFECTIVE RURAL WIDEBAND COMMUNICATIONS ARE OFTEN HAMPERED BY THE DIFFICULTY OF OBTAINING RIGHT-OF-WAY FOR CABLES AND/OR BY THE COST OF LEASED LINES OR SATELLITE CHANNELS. DIRECT RADIO LINKS WOULD BE ATTRACTIVE DUE TO THEIR NON-INTRUSIVE NATURE, POTENTIALLY LOWER COST, AND THEIR ABILITY TO BE MOVED AS REQUIREMENTS CHANGE. IN PRACTICE, DIRECT LINE-OF-SIGHT (LOS) MICROWAVE LINKS USUSALLY REQUIRE INTERMEDIATE RELAYS. TROPOSCATTER IS THE ONLY WIDEBAND TERRESTRIAL COMMUNICATIONS TECHNIQUE THAT CAN OFFER DIRECT LINKS. UNTIL RECENTLY, THIS TECHNOLOGY HAS FOUND FEW CIVILIAN APPLICATIONS DUE THE COST OF EQUIPMENT MAINTENANCE AND THE HIGH POWER LEVELS REQUIRED. WE BELIEVE THAT RECENT TECHNOLOGICAL ADVANCES HAVE MADE UNATTENDED OPERATION POSSIBLE AND THAT EQUIPMENT COST CAN BE DRAMATICALLY REDUCED. THE PROPOSED RESEARCH EFFORT WILL STUDY TECHNIQUES FOR REDUCING POWER LEVELS AND AVOIDING INTERFERENCE WITH OTHER USERS. POSSIBLE FREQUENCY BANDS FOR ALLOCATION TO THIS IMPORTANT RURAL SERVICE WILL BE STUDIED AND THE TECHNICAL PROBLEMS OF COMPRESSING VIDEO FOR TRANSMISSION ON THE FADING TROPO CHANNEL WILL BE ADDRESSED. THE EFFORT WILL BUILD ON RECENT TECHNICAL ADVANCES, INCLUDING EFFICIENT DIGITAL MODERN DESIGN, IMPROVED DIVERSITY RECEPTION SCHEMES, FORWARD ERROR CORRECTION CODING, AND BETTER ANTENNA SYSTEMS FOR SPATIAL DIVISION MULTIPLE ACCESS (SDMA).