Method and apparatus for interference suppression in orthogonal frequency division multiplexed (OFDM) wireless communication systems
First Claim
1. In a multi-point communications system having a receiver and transmitter disposed at a primary site for communication with a plurality of remote units disposed at respective secondary sites, an antenna comprising:
- multiple elements for receiving communications signals over a carrier frequency from a plurality of remote units, said elements being partitioned into groups disposed remote from one another by at least a predetermined minimum group spacing sufficient to obtain spatial diversity, each group containing at least one element, at least one group including multiple elements located proximate to one another and no further apart than a predetermined maximum element spacing to facilitate spatial filtering.
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Accused Products
Abstract
A method and apparatus for interference suppression in wireless communication systems, especially Orthogonal Frequency Division Multiplexed (OFDM) systems. The array apparatus includes a two-tier adaptive array system which provides for both spatial diversity and beamforming at the uplink. The adaptive array is comprised of sub-arrays spaced at a distance sufficient to provide spatial diversity, ideally 5 to 15 wavelengths at the frequency of operation. Each sub-array is composed of at least two antenna elements spaced in proximity sufficient to provide effective beamforming or scanning, ideally less then one-half of one wavelength at the frequency of operation. The Direction of Arrival (DOA) of signals impinging upon the array can be calculated by comparing signals from sub-array elements. Each sub-array can then be filtered or beamformed so as to provide high gain to desired signals received from the DOA (which may be a multipath signal) while at the same time damping out undesired signals such as co-channel interference (CCI) in the frequency band of operation. The DOA is also used in a method of allocating frequency bins for data signals, such as in an OFDMA system, to provide weighted guidelines for bin allocation to maximize received signal power.
235 Citations
34 Claims
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1. In a multi-point communications system having a receiver and transmitter disposed at a primary site for communication with a plurality of remote units disposed at respective secondary sites, an antenna comprising:
multiple elements for receiving communications signals over a carrier frequency from a plurality of remote units, said elements being partitioned into groups disposed remote from one another by at least a predetermined minimum group spacing sufficient to obtain spatial diversity, each group containing at least one element, at least one group including multiple elements located proximate to one another and no further apart than a predetermined maximum element spacing to facilitate spatial filtering. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a multi-point communications system having a receiver and transmitter disposed at a primary site for communication with a plurality of remote units disposed at respective secondary sites, a receiver subsystem comprising:
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means for receiving communications signals over frequency bins allocated to a plurality of remote units at a plurality of reception points, said reception points being spaced apart by a predetermined minimum spacing sufficient to facilitate spatial filtering; and
means for spatially filtering received signals. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34)
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17. In a multi-point communications system having a receiver and transmitter disposed at a primary site for communication with a plurality of remote units disposed at respective secondary sites, each remote unit transmitting and receiving communications data in frequency bins allocated thereto, a method for allocation of frequency bins as communications channels to the remote units, comprising:
identifying a direction of arrival of communications signals from the remote units; and
assigning remote units to frequency bins such that said frequency bins approximately adjacent to one another are allocated to remote units having directions of arrival that are distinctly separable from one another.
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23. In a multi-point communications system having a receiver and transmitter disposed at a primary site for communication with a plurality of remote units disposed at respective secondary sites, each remote unit transmitting and receiving communications data in frequency bins allocated thereto, a method for allocation of frequency bins as communications channels to the remote units, comprising:
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identifying a received signal power level of transmissions from remote units in use, said transmissions being received in active frequency bins;
determining differences between said received signal power levels in said active frequency bins of at least one neighborhood; and
reassigning remote units in use to active frequency bins such that said active frequency bins in at least one neighborhood have corresponding received signal power levels that differ by a minimal amount.
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29. A multi-point communications network comprising:
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a receiver and transmitter disposed at a primary site;
a plurality of remote units disposed at respective secondary sites for communication with said receiver and transmitter at said primary site;
said primary site having an antenna including multiple elements for receiving communications signals over a carrier frequency from a plurality of remote units, said elements being partitioned into groups disposed remote from one another by at least a predetermined minimum group spacing sufficient to obtain spatial diversity, each group containing at least one element, at least one group including multiple elements located proximate to one another and no further apart than a predetermined maximum element spacing to facilitate spatial filtering.
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Specification