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This two-year project will focus on system architectural design issues, traffic and fault management strategies, protocols, and digital modulation/coding for a totally wireless communication network involving radio cells, point-to-point millimeter wave links interconnecting the base stations, and access to LEO satellites.
Radio communications is today enjoying an absolute renaissance as technology for access to the world-wide telecommunications infrastructure. Not only has radio (in the form of cellular/PCS systems) freed the consumer from the tether of a telephone line but, perhaps even more important, broadband wireless loop brings forth the potential for resolving the last-mile dilemma: delivering multimegabit services to millions of subscribers, but without the crushing expense associated with the installation of new buried cabling. The research described in this proposal is targeted squarely at this newly emerging telecommunications environment, and a basic goal is the exploration of issues, novel system architectures, and key technologies appropriate for the totally wireless delivery of integrated broadband services to residential and business subscribers geographically dispersed over a very wide service area. The basic approach which we propose involves radio base stations, each serving all subscribers within some small area (say, 0.1 sq. km.). These are interconnected by point-to-point radio links at millimeter wavelength, and several base stations in each city serve as gateways to a Low Earth Orbit network of communication satellites. By means of this multi-tiered network, connectivity can be maintained between any pair of subscribers without requiring any new buried cabling and without using the installed network infrastructure of fiber trunks and backbone switches. In fact, the existing backbone network would be accessed only when connectivity is required between a wireless subscriber and a subscriber or database already wired to the backbone.
Radio communications today has emerged as a key technology for access to the world-wide telecommunication infrastructure. Not only has radio (in the form of cellular/PCS systems) freed the consumer from the tether of a telephone line but, perhaps even more important, broadband wireless loop brings forth the potential for resolving the last-mile dilemma: delivering multimegabit services to millions of subscribers, but without the crushing expense associated with the installation of new buried cabling. The research described in this proposal is targeted squarely at this newly emerging telecommunications environment, and a basic goal is the exploration of issues, novel system architectures, and key technologies appropriate for the totally wireless delivery of integrated broadband services to residential and business subscribers geographically dispersed over a very wide service area. The basic approach which we propose involves radio base stations, each serving all subscribers within some small area (say, 0.1 sq. km.). These are interconnected by a wider-area (say, city-wide) point-to-point radio mesh at millimeter wavelength. Furthermore, several nodes in each city-wide mesh serve as gateways to a Low Earth Orbit network of wirelessly interconnected satellites. By means of this multi-tiered network, point-to-point connectivity can be maintained between any pair of subscribers without requiring any new buried cabling and without using the installed network infrastructure of fiber trunks and backbone switches. In fact, the existing backbone network would be accessed only when connectivity is required between a wireless subscriber and a subscriber or database already wired to the backbone. We do not propose a radical new architecture capable of competing head-to-head against the installed base of WDM fiber cabling, computer controlled switches, IP routers, ATM, and intelligent network databases. Rather, we are proposing a strategy for enabling end-to-end broadband wireless connectivity, complementing the existing infrastructure, providing access to it, and potentially benefiting service providers, equipment suppliers, and subscribers, alike. This project will focus on the following set of issues: (1) virtual connection admission rules and routing algorithms for the terrestrial millimeter wave mesh which maintain quality-of-service guarantees for multiple classes of traffic; (2) fault management strategies which optimally reserve sufficient capacity on each millimeter wave cross link such that instantaneous recovery from rain-induced outages on these links can be effected with no dropped calls; (3) media access protocols for efficiently sharing a common communication channel created between several gateway nodes which may serve some region and a LEO satellite hovering over that region; and (4) design of the link level protocol and packet structure for reliable communication between gateways and satellites, and (5) digital modulation and coding strategies for enabling high speed operation of these millimeter-wave cross links at OC-3 rate (155 Mb/s). Specifically excluded from this proposal are studies pertaining to (a) the air interface between the subscribers and the base stations (this air-interface might very well conform with one of the 3rd Generation proposals currently under consideration by standards bodies world-wide), and (b) creation of, and traffic flow over, the links interconnecting the LEO satellites (these may very well be optical cross links which effectively combine high data rates, low cost, and low power consumption).
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CoRe Research Projects