Interference rejection method based on multiple sub-band projections
View Patent ↗This invention describes a cognitive radio signal processing where interference is mitigated using multiple frequency spatial projection to orthogonalize interference. The method is based on the well-known LMS solution of W=(A T A) −1 *d that is computed from received multi antenna and multicarrier signals in a novel way.
1. An OFDM symbols cognitive radio receiver signal processing method where interference is mitigated using multiple frequency domain spatial projections to orthogonalize interference comprising:
said OFDM symbols cognitive radio receiver receiving multiple receive signals that are each received using individual receive antennas;
said OFDM symbols cognitive radio receiver transforming said each received signal using Fourier or Fast Fourier Transforming resulting in complex outputs that are subcarriers containing subcarrier data for each OFDM symbol;
said OFDM symbols cognitive radio receiver processing said subcarrier data for each OFDM symbol by concatenating adjacent subcarrier data from groups of two or more consecutive OFDM symbols and then said OFDM symbols cognitive radio receiver creating a vector of multiple sub-band frequency domain spatial projections from said concatenated adjacent subcarrier data from groups of two or more consecutive OFDM symbols; and,
said OFDM symbols cognitive radio receiver multiplying said multiple received antenna signals by said vector to orthogonalize interference.
2. The interference mitigation method of claim 1 wherein the individual receive antennas are dual-polarized antennas.
3. The interference mitigation method of claim 1 wherein the method is used only if a threshold number of OFDM symbols are not being correctly received.
4. A hand held portable receiving device using an OFDM symbols cognitive radio signal processing method where interference is mitigated by said hand held portable receiving device using multiple frequency domain spatial projections to orthogonalize interference comprising:
said hand held portable receiving device receiving multiple receive signals that are each received using individual receive antennas;
said hand held portable receiving device having a processor for transforming said each received signal using Fourier or Fast Fourier Transforming resulting in complex outputs that are subcarriers containing subcarrier data for each OFDM symbol;
said hand held portable receiving device processor then processing said subcarrier data for each OFDM symbol by concatenating adjacent subcarrier data from groups of two or more consecutive OFDM symbols and then said hand held portable receiving device creating a vector of multiple sub-band frequency domain spatial projections from said concatenated adjacent subcarrier data from groups of two or more consecutive OFDM symbols; and,
said hand held portable receiving device multiplying said multiple received antenna signals by said vector to orthogonalize interference.
5. The hand held portable receiving device of claim 4 wherein the individual receive antennas are dual-polarized antennas.
6. The hand held portable receiving device of claim 4 wherein said interference mitigation is used only if a threshold number of OFDM symbols are not being correctly received.
7. The interference mitigation method claim 1 wherein said OFDM symbols cognitive radio receiver processing of said two or more adjacent subcarrier data comprises:
said OFDM symbols cognitive radio receiver creating a signal matrix A by concatenating k adjacent subcarrier data from two or more consecutive OFDM symbols where k is the number of consecutive OFDM symbols used into a M*(N*k) matrix A where M is the number of receive antennas and N is the number of adjacent subcarriers; and,
said OFDM symbols cognitive radio receiver transposing said matrix and computing the vector W of M complex coefficients using the formula W=(A T A) −1 *A T *d wherein the vector d is concatenated from k consecutive OFDM symbols such that the vector d is of dimension (N*k)*1.
8. The method of claim 4 wherein said hand held portable receiving device processing of said two or more adjacent subcarrier data comprises:
said hand held portable receiving device processor creating a signal matrix A by concatenating k adjacent subcarrier data from two or more consecutive OFDM symbols where k is the number of consecutive OFDM symbols used into a M*(N*k) matrix A where M is the number of receive antennas and N is the number of adjacent subcarriers; and,
said hand held portable receiving device processor transposing said matrix and computing the vector W of M complex coefficients using the formula W=(A T A) −1 *A T *d wherein the vector d is concatenated from k consecutive OFDM symbols such that the vector d is of dimension (N*k)*1.