Multi-signal transmit array with low intermodulation
First Claim
1. A transmitter for simultaneously transmitting n different signals in l directive beams, said transmitter comprising:
- n beamformers receiving n different signals with each beamformer receiving a signal to be transmitted, each of said beamformers having m outputs for each signal to be transmitted, and wherein said n beamformers have an m×
n output array;
m passive couplers each operatively connected to said n beamformers, wherein each passive coupler has n inputs for receiving said n different signals to be transmitted simultaneously from said n beamformers, each passive coupler having p outputs in phased relationship to one another; and
an antenna with an aperture within which a two-dimensional m×
p array of radiating elements are disposed, said radiating elements connected to the outputs of the passive couplers and transmitting said n different signals simultaneously in l directive beams, wherein each of said n beamformers receives steering control signals for determining the direction of transmission for each of said directive beams.
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Accused Products
Abstract
A transmitter is provided for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area. The transmitter includes a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted. A plurality of Butler matrices each receive one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship. An antenna is provided with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, and wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements. Each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.
91 Citations
53 Claims
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1. A transmitter for simultaneously transmitting n different signals in l directive beams, said transmitter comprising:
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n beamformers receiving n different signals with each beamformer receiving a signal to be transmitted, each of said beamformers having m outputs for each signal to be transmitted, and wherein said n beamformers have an m×
n output array;
m passive couplers each operatively connected to said n beamformers, wherein each passive coupler has n inputs for receiving said n different signals to be transmitted simultaneously from said n beamformers, each passive coupler having p outputs in phased relationship to one another; and
an antenna with an aperture within which a two-dimensional m×
p array of radiating elements are disposed, said radiating elements connected to the outputs of the passive couplers and transmitting said n different signals simultaneously in l directive beams,wherein each of said n beamformers receives steering control signals for determining the direction of transmission for each of said directive beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 35, 37, 39)
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14. A transmitter for simultaneously transmitting 2n different signals in 2l directive beams, said transmitter comprising:
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n beamformers receiving 2n different signals with each beamformer receiving two signals with first and second polarizations, respectively, each of said beamformers having m output pairs, for the first and second polarizations, where said n beamformers have a 2m×
n output array;
m passive coupler pairs each operatively connected to said n beamformers, wherein each passive coupler pair comprises a first passive coupler having n inputs for receiving n different signals of the first polarization, and a second passive coupler having n inputs for receiving n different signals of the second polarization, permitting all of said 2n different signals to be transmitted simultaneously, each of the first and second passive couplers having p outputs in phased relationship to one another defining 2p outputs for each passive coupler pair; and
an antenna with an aperture within which a two-dimensional m×
p array of dual-polarization radiating elements are connected to the outputs of the passive coupler pairs, with each element having a connection for the first polarization and a connection for the second polarization,wherein each of said n beamformers receives first and second steering control signals, for the first and second polarizations, respectively, for determining a direction of transmission for said directive beams.
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27. A transmitter for simultaneously transmitting n different signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate sub-region within a service area, said transmitter comprising:
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n beamformers receiving n different signals with each beamformer receiving a signal to be transmitted to an associated sub-region, each of said beamformers having m outputs for each different signal to be transmitted;
m passive couplers are operatively connected to said m outputs for receiving said n different signals to be transmitted simultaneously from said n beamformers, each passive coupler having r outputs in phased relationship to one another; and
an antenna with an aperture within which a two-dimensional q×
p array of radiating elements are disposed, with a fraction of adjacent radiating elements connected to the r outputs of each passive coupler,wherein n is less than or equal to the number of radiating elements coupled by each passive coupler, wherein each of said n beamformers receives steering control signals for steering the direction of each beam within its respective one of said sub-regions.
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34. A transmitter for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area, said transmitter comprising:
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a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted;
a plurality of Butler matrices each receiving one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship;
an antenna with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements, wherein each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.
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36. A method for providing simultaneous communication to a plurality of stationary user terminals located at known locations within a plurality of fan beams, said method comprising the steps of:
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defining a plurality of fan beams along a first axis, with each of the plurality of fans having a length along a second axis substantially perpendicular to the first axis;
providing a plurality of groups of directional transmitting beams, each of the groups of directional transmitting beams associated with a respective fan beam;
providing a plurality of communication signals each intended for a stationary user terminal;
determining which of the groups of directional transmitting beams to use for transmitting each of the plurality of communication signals to each respective destined preselected fixed user terminal;
multiplexing the plurality of communication signals on respective groups of directional transmitting beams associated with the respective destined stationary user terminal; and
transmitting the plurality of communication signals to each respective destined stationary user terminal via the signal multiplexed directional transmitting beam groups.
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38. A communications system for providing communication to a plurality of fixed user terminals located at a known locations within a grid of geographical cells, said communications satellite comprising:
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an orbiting satellite in a non-geostationary orbit defining a ground track;
a satellite-borne, multi-beam transmitter simultaneously creating a plurality of directional transmitting beams, each of said transmitting beams having a different angular displacement to the right or left of the satellite'"'"'s ground track and being electronically steerable in a plane approximately parallel to the satellite'"'"'s ground track via electronic steering signals; and
a satellite-borne, multi-beam receiver receiving signals from said user terminals including a destination location identifier signal of a terminal for which each signal is destined, said receiver translating the destination location identifier signals to determine which of said directional transmitting beams to use for transmitting each of said signals to its respectively indicated destination terminal.
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40. A scheduler for selecting data packets from a buffer memory to be transmitted in a next time period using multiple directional transmission beams controllable in direction, said scheduler comprising:
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a backlog tracker determining a waiting time for each data packet, said waiting time indicative of how long each data packet has waited in the buffer memory for transmission;
a first selector for selecting the data packet that has been waiting the longest as indicated by the backlog tracker; and
a second selector selecting further data packets for simultaneous transmission in descending order of waiting time, said second selector skipping data packets requiring a transmit direction incompatible with the direction of transmission of a data packet previously selected for transmission at a same time. - View Dependent Claims (41, 42, 43, 44, 46, 47, 48, 50, 51, 52, 53)
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45. A scheduling method for selecting data packets from a buffer memory for directive transmission using a number of directive beams, said method including the steps of:
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determining a subset of directions in which said directive beams can be transmitted in a next transmission;
mapping a destination identifier code stored with each said data packets to a corresponding beam direction and selecting only data packets whose destinations map to a direction within said subset of directions;
ordering said selected data packets according to how long they have been stored in said buffer memory, with said selected data packets which have been stored the longest ordered first; and
transmitting the selected data packets that have been stored the longest first.
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49. A method of preventing fraudulent or unauthorized use of a communication satellite, said method comprising the steps of:
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providing a logon procedure in which a user terminal desirous of service communicates with a network computer using an authentication procedure based on shared secret data to establish a session key;
storing the session keys for logged-on user terminals in the satellite;
using the session keys in said user terminals to provide transmission from the user terminals to the satellite with a verifiable signature;
checking the signature of signals received at the satellite using the stored session keys to verify the identity of the source; and
transmitting signals received at the satellite to their indicated destinations only if the identity of the source is verified to be an authentic user terminal.
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Specification