Adaptive time diversity and spatial diversity for OFDM
First Claim
1. An apparatus for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the apparatus comprising:
- a receiver that responds to receipt of the at least one OFDM signal by making a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity.
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Accused Products
Abstract
An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.
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Citations
67 Claims
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1. An apparatus for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the apparatus comprising:
a receiver that responds to receipt of the at least one OFDM signal by making a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 37, 40, 46, 48, 54, 60)
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9. An apparatus for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the apparatus comprising:
at least one controller configured and arranged to respond to a feedback signal, the feedback signal indicative of a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier, to direct an encoder to assign constellation points for the time diversity or the spatial diversity to the sub-carrier, the encoder including a space time transmitter diversity (STTD) encoder and a spatial multiplexing (SM) encoder, the STTD encoder being arranged to encode the sub-carrier in accordance with the time diversity and the SM encoder being arranged to encode the sub-carrier in accordance with the spatial diversity, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity. - View Dependent Claims (10, 41, 49, 55, 61)
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11. An apparatus for use with an adaptive orthogonal frequency division multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the apparatus comprising:
controllers configured and arranged to direct transmission and reception in accordance with OFDM, the controllers including those associated with the reception that are configured to respond to receipt of the at least one OFDM signal by making a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity, the controllers including those associated with the transmission that are responsive to receipt of the feedback signal to direct an encoder to assign constellation points for either the time diversity or the spatial diversity to the sub-carrier, the encoder including a space time transmitter diversity (STTD) encoder and a spatial multiplexing (SM) encoder, the STTD encoder being arranged to encode the sub-carrier in accordance with the time diversity and the SM encoder being arranged to encode the sub-carrier in accordance with the spatial diversity. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 42, 50, 56, 62)
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20. A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
responding to receipt of the OFDM signal by making a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity. - View Dependent Claims (21, 22, 23, 24, 25, 26, 38, 43, 47, 51, 57, 63)
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27. A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
responding to a feedback signal, the feedback signal indicative of a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier, to direct an encoder to assign constellation points for the time diversity or the spatial diversity to the sub-carrier, the encoder including a space time transmitter diversity (STTD) encoder and a spatial multiplexing (SM) encoder, the STTD encoder being arranged to encode the sub-carrier in accordance with the time diversity and the SM encoder being arranged to encode the sub-carrier in accordance with the spatial diversity, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity. - View Dependent Claims (28, 39, 44, 52, 58, 64)
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29. A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
directing transmission and reception in accordance with OFDM by using controllers, the controllers including those associated with the reception responding to receipt of the at least one OFDM signal by making a determination for a sub-carrier of the plurality of sub-carriers as to whether time diversity or spatial diversity should be used for subsequent transmission on the sub-carrier and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted on the sub-carrier over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity, the controllers including those associated with the transmission that respond to receipt of the feedback signal to direct an encoder to assign constellation points for the time diversity or the spatial diversity to the sub-carrier, the encoder including a space time transmitter diversity (STTD) encoder and a spatial multiplexing (SM) encoder, the STTD encoder being arranged to encode the sub-carrier in accordance with the time diversity and the SM encoder being arranged to encode the sub-carrier in accordance with the spatial diversity. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 45, 53, 59, 65)
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66. A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
responding to receipt of the OFDM signal by making a determination as to whether time diversity or spatial diversity should be used for subsequent transmission and transmitting a feedback signal indicative of that determination, wherein OFDM data signals that are transmitted over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity and wherein the determination is based on a channel condition indicated by a criteria selected from the group of criteria consisting of an eigen value of a channel matrix, an element in a diagonal of the channel matrix and a plurality of eigen values of the channel matrix.
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67. A method for use with an adaptive orthogonal frequency division-multiplexing (OFDM) system that uses multiple input multiple output (MIMO) structure to transmit OFDM signals from a plurality of transmitter antennas to a plurality of receiver antennas, at least one of the OFDM signals having an OFDM frame of a duration, the OFDM frame having data packets and a plurality of OFDM slots, each of the OFDM slots having a plurality of OFDM symbols that include a plurality of sub-carriers, the method comprising:
responding to a feedback signal to direct an encoder to assign constellation points for time diversity or spatial diversity to at least one sub-carrier of the plurality of sub-carriers in accordance with a channel condition, the encoder including a space time transmitter diversity (STTD) encoder and a spatial multiplexing (SM) encoder, the STTD encoder being arranged to encode the at least one sub-carrier in accordance with time diversity and the SM encoder being arranged to encode the at least one sub-carrier in accordance with spatial diversity, wherein OFDM data signals that are transmitted over multiple ones of the transmitter antennas are independent of each other for the spatial diversity and correspond to each other for the time diversity and wherein the channel condition is determined based on a criteria selected from the group of criteria consisting of an eigen value of a channel matrix, an element in a diagonal of the channel matrix and a plurality of eigen values of the channel matrix.
Specification