MIMO receivers having one or more additional receive paths

A method for receiving M multi-carrier signals transmitted from M transmit antennas, M>1, the method comprising:

• receiving the M multi-carrier signals at at least (M+1) receive paths;
• separating, in each receive path, the received signals into separate subcarrier signals;
• and
• processing the separate subcarrier signals to generate a recovered version of each of the M transmitted multi-carrier signals, wherein the processing comprises:
• receiving the separate subcarrier signals from each receive path and generating M first signals, each first signal containing (1) desired signal corresponding to one of the transmit antennas and (2) interference;
• receiving the separate subcarrier signals from each receive path and generating a second signal representative of the interference in the M first signals;
• and
• combining each first signal with a portion of the second signal to generate a recovered signal having less interference than said each first signal.

A wireless communications system comprising:

• a transmitter having M transmit antennas adapted to transmit M multi-carrier signals, M>1;
• and
• a receiver having:
• at least (M+1) receive paths, each receive path adapted to receive the M multi-carrier signals and separate the received signals into separate subcarrier signals;
• and
• a processor adapted to process the separate subcarrier signals to generate a recovered version of each of the M transmitted multi-carrier signals, wherein the processor comprises:
• a first processing block adapted to receive the separate subcarrier signals from each receive path and to generate M first signals, each first signal containing (1) desired signal corresponding to one of the transmit antennas and (2) interference;
• a second processing block adapted to receive the separate subcarrier signals from each receive path and to generate a second signal representative of the interference in the M first signals;
• and
• an interference cancellation block adapted to combine each first signal with a portion of the second signal to generate a recovered signal having less interference than said each first signal.

A receiver for receiving M multi-carrier signals transmitted from M transmit antennas, M>1, the receiver comprising:

• at least (M+1) receive paths, each receive path adapted to receive the M multi-carrier signals and separate the received signals into separate subcarrier signals;
• and
• a processor adapted to process the separate subcarrier signals to generate a recovered version of each of the M transmitted multi-carrier signals, wherein each receive path comprises:
• a receive antenna adapted to receive the multi-carrier signals;
• an analog-to-digital converter adapted to digitize the received multi-carrier signals;
• and
• a transform block adapted to convert the digitized multi-carrier signals in a time domain into the separate subcarrier signals in a frequency domain, wherein the transform block comprises:
• a first transformer adapted to convert an initial set of the digitized multi-carrier signals into an initial set of separate subcarrier signals in the frequency domain;
• and
• a second transformer adapted to convert subsequent sets of the digitized multi-carrier signals into subsequent sets of separate subcarrier signals in the frequency domain based on the initial set of separate subcarrier signals, wherein:
• the initial set of digitized multi-carrier signals does not have cyclic prefixes;
• and
• the subsequent sets of digitized multi-carrier signals have cyclic prefixes.

A receiver for receiving M multi-carrier signals transmitted from M transmit antennas, M>1, the receiver comprising:

• at least (M+1) receive paths, each receive path adapted to receive the M multi-carrier signals and separate the received signals into separate subcarrier signals;
• and
• a processor adapted to process the separate subcarrier signals to generate a recovered version of each of the M transmitted multi-carrier signals, wherein each receive path comprises:
• a receive antenna adapted to receive the multi-carrier signals;
• an analog-to-digital converter adapted to digitize the received multi-carrier signals;
• and
• a transform block adapted to convert the digitized multi-carrier signals in a time domain into the separate subcarrier signals in a frequency domain, wherein the transform block comprises:
• a first transformer adapted to convert an initial set of the digitized multi-carrier signals into an initial set of separate subcarrier signals in the frequency domain;
• and
• a second transformer adapted to convert subsequent sets of the digitized multi-carrier signals into subsequent sets of separate subcarrier signals in the frequency domain based on the initial set of separate subcarrier signals, wherein the second transformer is adapted to apply recursive filtering in converting the subsequent sets of the digitized multi-carrier signals into the subsequent sets of separate subcarrier signals, wherein the recursive filtering of the second transformer is based on a recursive relationship given by:
• Xk(i+1)=W−k[Xk(i)+x(i+N)−x(i)],
• where x(i+N) is an input signal to the recursive filtering and Xk(i+1) is an output signal from the recursive filtering.

A receiver for receiving M multi-carrier signals transmitted from M transmit antennas, M>1, the receiver comprising:

• at least (M+1) receive paths, each receive path adapted to receive the M multi-carrier signals and separate the received signals into separate subcarrier signals;
• and
• a processor adapted to process the separate subcarrier signals to generate a recovered version of each of the M transmitted multi-carrier signals, wherein each receive path comprises:
• a receive antenna adapted to receive the multi-carrier signals;
• an analog-to-digital converter adapted to digitize the received multi-carrier signals;
• and
• a transform block adapted to convert the digitized multi-carrier signals in a time domain into the separate subcarrier signals in a frequency domain, wherein the transform block comprises:
• a first transformer adapted to convert an initial set of the digitized multi-carrier signals into an initial set of separate subcarrier signals in the frequency domain;
• and
• a second transformer adapted to convert subsequent sets of the digitized multi- carrier signals into subsequent sets of separate subcarrier signals in the frequency domain based on the initial set of separate subcarrier signals, wherein the second transformer is adapted to apply recursive filtering in converting the subsequent sets of the digitized multi-carrier signals into the subsequent sets of separate subcarrier signals, wherein the recursive filtering of the second transformer is based on a filter comprising:
• an N-cycle delay adapted to delay an input signal to the filter;
• an amplifier adapted to amplify an output signal from the filter;
• a 1-cycle delay adapted to delay the amplified output signal;
• and
• a summation node adapted to generate the output signal by subtracting the N-cycle delayed input signal from a sum of the input signal and the 1-cycle delayed, amplified output signal.