MIMO OFDM system
AssigneeAT&T Intellectual Property II, L.P.
InventorsYe Li, Nelson Ray Sollenberger, Jack Harriman Winters
Life of this patent
Estimating the term…
Abstract
A MIMO OFDM system includes a plurality of space-time encoders for encoding respective data blocks with independent space-time codes. The transformed data block signals are transmitted by a plurality of transmit antennas and received by a plurality of receive antennas. The received data is pre-whitened prior to maximum likelihood detection. In one embodiment, successive interference cancellation can be sued to improve system performance. Channel parameter estimation can be enhanced by weighting the channel impulse response estimates based upon a deviation from average.
Claims8
A receiver constructed to receive signals from a remote unit that at time n transmits a data block bi[n,k] over two transmit antennas and transmits a data block b2[n,k] over two other transmit antennas, where k is a tone and k=0, 1, 2, . . . , comprising:
- N receive antennas, each receiving a signal that includes signals related to the signals transmitted by the transmit antennas of the remote unit, where N is equal or greater than 4;
- N fast Fourier transform (FFT) modules, each coupled to an associated one of said receive antennas;
- a space-time processing (STP) unit, responsive to said FFT modules, to pre-whiten signals supplied to said STP unit and to perform maximum likelihood detection on each of the pre-whitened signals, and which, when initially detecting data pertaining to block b1[n,k] treats other received signals, including signals received from the antennas that transmit data pertaining to block b2[n,k], as interfering noise, and when initially detecting data pertaining to block b2[n,k] treats other received signals, including signals received from the antennas that transmit data pertaining to block b1[n,k], as interfering noise;
- a first space-time decoder responsive to output signals of said STP unit for decoding block b1[n,k] ;
- a second space-time decoder responsive to output signals of said STP unit for decoding block b2[n,k];
- and
- a channel parameter estimator responsive to output signals of said FFT modules and output signals of said space-time decoders, for developing parameter estimates of channels between the remote unit and the receiver, and applying the developed parameter estimates to said space-time decoders.
A method comprising:
- at each of N receive antennas, receiving a signal that includes signals related to signals transmitted from a remote unit at time n, the signals including a data block b1[n,k] transmitted over first transmit antennas and a data block b2[n,k] transmitted over second transmit antennas, where k is a tone and k=0, 1, 2, . . . , where N is equal or greater than 4;
- transforming the received signal in N fast Fourier transform (FFT) modules coupled to an associated one of said receive antennas and generating respective transformed signals;
- receiving the transformed signals at a space-time processing unit and pre-whitening signals in the space-time processing unit associated with the data blocks b1[n,k] and b2[n,k] and performing maximum likelihood detection on each of the pre-whitened signals, and when initially detecting data pertaining to block b1[n,k] treating other received signals, including signals received from the second transmit antennas that transmit data pertaining to block b2[n,k], as interfering noise, and when initially detecting data pertaining to block b2[n,k] treating other received signals, including signals received from the first transmit antennas that transmit data pertaining to block b1[n,k], as interfering noise;
- decoding block b1[n,k] in a first space-time decoder;
- decoding block b2[n,k] in a second space-time decoder;
- developing channel parameter estimates using output signals of said FFT modules and output signals of said space-time decoders;
- and
- using the channel parameter estimates in said first and second space-time decoders.
Dependencies are inferred from the claim text.