Joint demodulation using spatial maximum likelihood
First Claim
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1. A method of communicating between a plurality of spatially distributed mobile radio units and a radio network using the same radio frequency, comprising the steps of:
- transmitting information symbols simultaneously from said mobile units on said same radio frequency;
sampling a radio wave on said same radio frequency at different points in space using a plurality of spatially distributed antennas to produce spatial signal samples; and
jointly processing said spatial signal samples using an equalizer adapted to resolve spatial intersymbol interference between said information symbols in order to reproduce said transmitted information symbols.
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Abstract
Methods and systems for processing signals in radio communication systems are described which include processes for handling co-channel interference while reducing the number of Viterbi states being processed. A spatial analogy to the Viterbi MLSE process is provided. Both the uplink and downlink cases are described.
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Citations
32 Claims
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1. A method of communicating between a plurality of spatially distributed mobile radio units and a radio network using the same radio frequency, comprising the steps of:
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transmitting information symbols simultaneously from said mobile units on said same radio frequency; sampling a radio wave on said same radio frequency at different points in space using a plurality of spatially distributed antennas to produce spatial signal samples; and jointly processing said spatial signal samples using an equalizer adapted to resolve spatial intersymbol interference between said information symbols in order to reproduce said transmitted information symbols. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of communicating between a plurality of mobile radio units and a radio network using a first plurality of radio frequencies, comprising the steps of:
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transmitting information symbols simultaneously from said mobile units using, for each mobile unit, an associated one of said plurality of radio frequencies; sampling a radio wave on all of said radio frequencies using a multi-channel receiver to produce samples along a frequency domain; and jointly processing said frequency-domain samples using an equalizer adapted to resolve frequency-domain intersymbol interference between signals on adjacent ones of said plurality of radio frequencies in order to reproduce said transmitted information symbols.
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14. A method of communicating between a plurality of spatially distributed mobile radio units and a radio network using the same radio frequency, comprising the steps of:
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transmitting information symbols simultaneously from said mobile units on said same radio frequency; sampling a radio wave on said radio frequency at different points in space using a plurality of spatially distributed antennas to produce spatial signal samples; determining for each of said antennas a group of mobile units whose transmissions are significant contributors to that antenna'"'"'s signal to yield grouping information; and processing said spatial signal samples sequentially in an order dependent on said grouping information in order to reproduce said transmitted information symbols. - View Dependent Claims (15)
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16. A method of communicating between a plurality of spatially distributed mobile radio units and a radio network using a plurality of radio frequencies, comprising the steps of:
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transmitting information symbols simultaneously from said mobile units using, for each mobile unit, an associated one of said plurality of radio frequencies; sampling a radio wave on a number of said plurality of radio frequencies using a multi-frequency receiver to produce samples along a frequency domain; determining, for each of said number of frequencies, a group of mobile units whose transmissions are significant contributors to a signal received on that frequency to produce grouping information; and processing said frequency domain samples sequentially in an order dependent on said grouping information in order to reproduce said transmitted information symbols. - View Dependent Claims (17)
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18. A method of communicating between groups of spatially distributed mobile radio units and a radio network using the same radio frequency for mobiles in the same group, comprising the steps of:
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grouping mobile units into groups that use the same radio frequency to facilitate demodulation of the symbols transmitted by the mobiles within a group by a spatial equalizer; transmitting information symbols simultaneously from mobile units in the same group using the same radio frequency; sampling a radio wave for each said group frequency at different points in space using a plurality of spatially distributed antennas to produce spatial signal samples; and jointly processing said spatial signal samples using a spatial equalizer for each group adapted to resolve spatial intersymbol interference between mobiles in the group in order to reproduce information symbols transmitted by mobiles in said group. - View Dependent Claims (19, 20, 21)
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22. A communications system for receiving information symbols transmitted from a number of spatially distributed mobile units using a number of directive antenna beams, comprising:
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signal correlation means for determining correlations indicating an amplitude and phase of signals transmitted from said mobile units and received using said beams; sorting means for processing said correlations to further determine for each received beam signal a group of mobile units whose transmitted symbols are significant contributors to that beam to provide grouping information; and signal spatial equalizer means for sequentially processing said beam signals in an order determined by said grouping information to resolve said information symbols transmitted by said mobile units. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A communications system for receiving information symbols transmitted from a plurality of spatially distributed mobile units using a plurality of antenna elements, comprising:
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combining means for combining signals received using said plurality of antenna elements to form a plurality of beam signals corresponding to signals received from particular directions; signal correlation means for determining correlations indicating an amplitude and phase of signals transmitted from said mobile units and contained in said beam signals; sorting means for processing said correlations to further determine for each formed beam signal a group of mobile units whose transmitted symbols are significant contributors to that beam signal to provide grouping information; and spatial equalizer means for sequentially processing said beam signals in an order determined by said grouping information to resolve said information symbols transmitted by said mobile units. - View Dependent Claims (30)
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31. A method of communicating between a plurality of spatially distributed mobile radio units and a radio network using the same radio channel frequency, comprising the steps of:
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transmitting information symbols simultaneously from said mobile units on said same radio frequency; sampling a radio wave on said radio frequency using a plurality of antenna elements to produce antenna signal samples; processing said antenna signal samples using a beam forming network to separate signals received from different directions to obtain direction-corresponding beam signals each beam being a weighted sum of signals transmitted from a different subset of said mobile radio units wherein at least two of said subsets include a signal from a same mobile radio unit; and jointly processing said beam signals associated with said at least two of said subsets using a spatial equalizer adapted to resolve intersymbol interference between information symbols received from different mobile units in angularly adjacent beams in order to reproduce said transmitted information symbols.
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32. A two-way communications method for communicating between a plurality of mobile units and a fixed network, comprising the steps of:
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transmitting uplink information from at least two of said mobile units to said fixed network using the same radio frequency; using a spatial equalizer in said fixed network to resolve spatial intersymbol interference between said at least two mobile signals to reproduce said transmitted uplink information; forming a second plurality of downlink signals for transmission by respective transmitters of said fixed network, each downlink signal including symbols to be transmitted to a different plurality of said mobile units; transmitting downlink information from said fixed network to said mobile units using a second plurality of transmitters; and jointly processing at least one mobile unit signals received from at least two of said plurality of transmitters to reproduce a portion of said downlink information intended for said at least one mobile unit.
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Specification