SYSTEM AND METHOD FOR DISTRIBUTED INPUT DISTRIBUTED OUTPUT WIRELESS COMMUNICATIONS
First Claim
1. A method for compensating for in-phase and quadrature (I/Q) imbalances in a multiple antenna system (MAS) with multi-user (MU) transmissions (“
- MU-MAS”
) comprising;
transmitting a training signal from each antenna of a base station to each of a plurality of wireless client devices, each of the client devices analyzing each training signal to generate channel characterization data, and receiving the channel characterization data at the base station;
computing a plurality of MU-MAS precoder weights based on the channel characterization data, the MU-MAS precoder weights calculated to pre-cancel interference due to I/Q gain and phase imbalances and/or inter-user interference;
precoding data using the MU-MAS precoder weights to generate precoded data signals for each antenna of the base station; and
transmitting the precoded data signals through each antenna of the base station to each respective client device.
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Abstract
A system for compensating for in-phase and quadrature (I/Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM). For example, one embodiment of the system comprises one or more coding modulation units to encode and modulate information bits for each of a plurality of wireless client devices to produce encoded and modulated information bits; one or more mapping units to map the encoded and modulated information bits to complex symbols; and a MU-MAS or DIDO IQ-aware precoding unit to exploit channel state information obtained through feedback from the wireless client devices to compute MU-MAS or DIDO IQ-aware precoding weights, the MU-MAS or DIDO IQ-aware precoding unit precoding the complex symbols obtained from the mapping units using the weights to pre-cancel interference due to I/Q gain and phase imbalances and/or inter-user interference.
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Citations
22 Claims
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1. A method for compensating for in-phase and quadrature (I/Q) imbalances in a multiple antenna system (MAS) with multi-user (MU) transmissions (“
- MU-MAS”
) comprising;transmitting a training signal from each antenna of a base station to each of a plurality of wireless client devices, each of the client devices analyzing each training signal to generate channel characterization data, and receiving the channel characterization data at the base station; computing a plurality of MU-MAS precoder weights based on the channel characterization data, the MU-MAS precoder weights calculated to pre-cancel interference due to I/Q gain and phase imbalances and/or inter-user interference; precoding data using the MU-MAS precoder weights to generate precoded data signals for each antenna of the base station; and transmitting the precoded data signals through each antenna of the base station to each respective client device. - View Dependent Claims (3, 4, 5, 6)
- MU-MAS”
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8. The system as in claim 7 further comprising:
one or more orthogonal frequency division multiplexing (OFDM) units to receive the precoded signals from the MU-MAS IQ-aware precoding unit and to modulate the precoded signals according to an OFDM standard. - View Dependent Claims (9, 10)
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11. The system as in claim 7 wherein the MU-MAS IQ-aware precoding unit is implemented as a minimum mean square error (MMSE), a weighted MMSE or a zero-forcing (ZF) precoder.
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12. The system as in claim 7 wherein the MU-MAS precoding unit is implemented as a minimum mean square error (MMSE), a weighted MMSE, a zero-forcing (ZF) or a block diagonalization (BD) precoder.
- 13. The system as in claim 7 wherein the MU-MAS communication comprises DIDO communication and wherein the system comprises a DIDO IQ-aware precoding unit to exploit channel state information obtained through feedback from the wireless client devices to compute DIDO IQ-aware precoding weights, the DIDO IQ-aware precoding unit precoding the complex symbols obtained from the mapping units using the weights to pre-cancel interference due to I/Q gain and phase imbalances and/or inter-user interference.
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15. The system as in claim 14 where the channel estimates are computed in the time domain by using the input to the OFDM units
- 16. The wireless client device as in claim 14 wherein the feedback generator unit further comprises logic for quantizing the channel estimates prior to transmission to the base station.
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17. The wireless client device as in claim 14 further comprising:
an I/Q-aware receiver unit which receives outputs from the OFDM units and responsively computes the IQ receiver and demodulates/decodes the signal to obtain the estimate of the transmitted data.
Specification