System and method for blind compensation and correction of transmitter IQ imbalance at the receiver
View Patent ↗Systems and methods of correcting for a transmitter IQ imbalance are disclosed. Various embodiments collect statistics related to a received packet on a transceiver. These statistics include one or more transmitter imbalance parameters. In some embodiments, an estimated inversion matrix is calculated based on the imbalance parameter and a correction for the IQ imbalance is made by applying the inversion matrix to a sub-carrier and the sub carrier's image.
1. A method of correcting for a transmitter Inphase Quadrature (IQ) imbalance comprising:
collecting statistics related to a received packet on a transceiver, the statistics comprising samples from at least one pair of symmetric sub-carriers obtained after receiver IQ compensation and channel equalization;
calculating an estimation factor of based on the collected statistics, wherein α tx and β tx are derived from the transmitter IQ imbalance, and η tx is a normalizing factor;
calculating an imbalance parameter using the estimation factor;
calculating an estimated inversion matrix based on the imbalance parameter; and
correcting for the IQ imbalance by applying the inversion matrix to the pair of symmetric sub-carriers.
2. The method of claim 1 , wherein the statistics are collected over a series of symbols in one packet.
3. The method of claim 1 , wherein the statistics are collected over a series of packets.
4. The method of claim 1 , wherein the statistics comprise samples from a plurality of pairs of symmetric sub-carriers.
5. The method of claim 1 , wherein the statistics are collected over a series of symbols and a series of packets and comprise samples from a plurality of pairs of symmetric sub-carriers.
6. The method of claim 1 , wherein the statistics are collected over a range of data bit transmissions depending on Fast Fourier Transform (FFT) size.
7. The method of claim 1 , wherein the statistics are collected over a range of data bit transmissions depending on filter characteristics.
8. The method of claim 1 , wherein the statistics are collected over a range of data bit transmissions depending on implementation complexity.
9. The method of claim 1 , further comprising calculating K −1 tx wherein K tx is a transmit IQ imbalance matrix.
10. The method of claim 1 , further comprising averaging over time and across sub-carriers to establish the estimation factor.
11. The method of claim 1 , further comprising constructing an inverse matrix of IQ imbalance based on the estimation factor.
12. A communication device comprising:
a receiver configured to receive packets; a processor, coupled to the receiver and configured to execute instructions;
a memory, coupled to the processor and configured to store instructions causing the device to:
collect statistics related to a received packet, the comprising samples from at least one pair of symmetric sub-carriers obtained after receiver Inphase Quadrature (IQ) compensation and channel equalization;
calculate an estimation factor of based on the collected statistics, wherein α tx and β tx are derived from the transmitter IQ imbalance, and η tx is a normalizing factor;
calculate an imbalance parameter using the estimation factor;
calculate an estimated inversion matrix based on the imbalance parameter; and
correct for the IQ imbalance by applying the inversion matrix to the pair of symmetric sub-carriers.
13. The device of claim 12 , wherein the instructions further cause the device to collect statistics over a series of symbols within one packet.
14. The device of claim 12 , wherein the instructions further cause the device to collect statistics over a series of packets.
15. The device of claim 12 , wherein the instructions further cause the device to collect statistics comprising samples from a plurality of pairs of symmetric sub-carriers.
16. The device of claim 12 , wherein the instructions are further configured to cause the device to collect statistics over a range of data hit transmissions depending on Fast Fourier Transform (FFT) size.
17. The device of claim 12 , wherein the instructions are further configured to cause the device to collect statistics over a range of data bit transmissions depending on filter characteristics.
18. The device of claim 12 , wherein the instructions are further configured to cause the device to collect statistics over a range of data bit transmissions depending on implementation complexity.
19. The device of claim 12 , wherein the instructions are further configured to cause the device to compute K −1 tx based on the statistics collected wherein K tx is a transmit IQ imbalance matrix.