Subtractive CDMA system with simultaneous subtraction in code space and direction-of-arrival space
First Claim
1. A communications system comprising a plurality of mobile stations and an improved base station for receiving signals from said mobile stations and decoding information-bearing signals transmitted therefrom, comprising:
- antenna means comprising antenna elements disposed around a support structure for receiving signals transmitted from said plurality of mobile stations and generating output signals from each antenna element;
conversion means for amplifying, filtering and converting signals from each of said antenna elements into a corresponding number of converted signals for processing;
storage means for temporarily storing a number of samples of said converted signals; and
processing means for iteratively processing and reprocessing said stored samples successively to decode said information from each of said mobile stations in turn, wherein the processing provided by said processing means identifies from said stored samples an information symbol transmitted by one of said mobile stations thereby decoding said information-bearing signal and subtracts values dependent on said identified information symbol from said stored samples thereby reducing interference between the just-decoded signal and the signal to be decoded at a subsequent iteration.
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Accused Products
Abstract
A communications system is disclosed comprising a plurality of mobile stations and an improved base station for receiving signals from said mobile stations and decoding information-bearing signals transmitted therefrom. An antenna comprising antenna elements disposed around a support structure receives signals transmitted from the plurality of mobile stations and generates output signals from each antenna element. Convertors amplify, filter and convert signals from each of the antenna elements into a corresponding number of converted signals for processing. Storage devices temporarily store a number of samples of the converted signals. Processors iteratively process and reprocess the stored samples successively to decode the information from each of the mobile stations in turn. The processing provided by the processors identifies from the stored samples an information symbol transmitted by one of the mobile stations thereby decoding the information-bearing signal, and subtracts values dependent on the identified information symbol from the stored samples thereby reducing interference between the just-decoded signal and the signal to be decoded at a subsequent iteration.
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Citations
39 Claims
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1. A communications system comprising a plurality of mobile stations and an improved base station for receiving signals from said mobile stations and decoding information-bearing signals transmitted therefrom, comprising:
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antenna means comprising antenna elements disposed around a support structure for receiving signals transmitted from said plurality of mobile stations and generating output signals from each antenna element; conversion means for amplifying, filtering and converting signals from each of said antenna elements into a corresponding number of converted signals for processing; storage means for temporarily storing a number of samples of said converted signals; and processing means for iteratively processing and reprocessing said stored samples successively to decode said information from each of said mobile stations in turn, wherein the processing provided by said processing means identifies from said stored samples an information symbol transmitted by one of said mobile stations thereby decoding said information-bearing signal and subtracts values dependent on said identified information symbol from said stored samples thereby reducing interference between the just-decoded signal and the signal to be decoded at a subsequent iteration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A communications system comprising a plurality of mobile stations and an improved base station for receiving signals transmitted from said mobile stations each with the aid of an assigned access code and for decoding information symbols belonging to an allowed alphabet of symbols encoded in said transmissions, comprising:
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antenna means comprising antenna elements disposed around a support structure for receiving signals transmitted from said plurality of mobile stations and generating output signals from each antenna element; conversion means for amplifying, filtering and converting signals from each of said antenna elements into a corresponding number of converted signals for processing; storage means for temporarily storing a number of samples of said signals converted from each of said antenna elements at successive instants in time; and two-dimensional numerical transform means for processing said stored samples using one of said access codes assigned to a first one of said mobile stations to produce a two-dimensional array of transformed samples, said transformed samples lying along one dimension of said two-dimensional array corresponding to different possible directions of arrival of signals at said base station transmitted by said first mobile station and transformed samples lying along the other dimension of said two-dimensional array corresponding to correlations with different ones of said information symbols in an allowed alphabet of symbols. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A communications system comprising a plurality of mobile stations and an improved base station for receiving signals transmitted from said mobile stations each with the aid of an assigned access code and for decoding information symbols belonging to an allowed alphabet of symbols encoded in said transmissions, comprising:
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antenna means comprising antenna elements disposed around a support structure for receiving signals transmitted from said plurality of mobile stations and generating output signals from each antenna element; conversion means for amplifying, filtering and converting signals from each of said antenna elements into a corresponding number of converted signals for processing; storage means for temporarily storing a number of samples of said signals converted from each of said antenna elements at successive instants in time; two-dimensional numerical transform means for processing said stored samples using one of said access codes assigned to a first one of said mobile stations to produce a two-dimensional array of transformed samples, said transformed samples lying along one dimension of said two-dimensional array corresponding to different possible directions of arrival of signals at said base station transmitted by said first mobile station and transformed samples lying along the other dimension of said two-dimensional array corresponding to correlating samples with different ones of said information symbols in an allowed alphabet of symbols using a prescribed time-shift between the samples correlated and said information symbols; and means for repeating said two-dimensional transform for a plurality of said time-shifts corresponding to delayed reception of signals from said first mobile station corresponding to delayed echoes of said signals caused by signals reflection from objects in the propagation path. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. A method for receiving signals transmitted from a plurality of mobile stations, in a communication system comprising said mobile stations and an improved base station, each with the aid of an assigned access code and for decoding information symbols belonging to an allowed alphabet of symbols encoded in said transmissions, comprising the steps of:
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receiving signals transmitted from said plurality of mobile stations at antenna means with antenna elements disposed around a support structure and generating output signals from each antenna element; amplifying, filtering and converting signals from each of said antenna elements into a corresponding number of converted signals for processing; temporarily storing a number of samples of said signals converted from each of said antenna elements at successive instants in time; processing said stored samples using one of said access codes assigned to a first one of said mobile stations to produce a two-dimensional array of transformed samples, said transformed samples lying along one dimension of said two-dimensional array corresponding to different possible directions of arrival of signals at said base station transmitted by said first mobile station and transformed samples lying along the other dimension of said two-dimensional array corresponding to correlating samples with different ones of said information symbols in an allowed alphabet of symbols using a prescribed time-shift between the samples correlated and said information symbols; and repeating said two-dimensional transform for a plurality of said time-shifts corresponding to delayed reception of signals from said first mobile station corresponding to delayed echoes of said signals caused by signals reflection from objects in the propagation path. - View Dependent Claims (34, 35, 36, 37, 38, 39)
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Specification