Interference mitigation for devices with multiple receivers
Methods and systems for mitigating interference or estimating a covariance matrix in a communication system are disclosed. A method of demodulating a received signal in a communication system can include receiving a first plurality of waveforms, estimating a covariance matrix based on the first plurality of waveforms, determining a spatial filter based on the estimated covariance matrix, receiving a second plurality of waveforms, generating at least one filtered waveform by applying the spatial filter to the second plurality of waveforms, and demodulating the at least one filtered waveform.
1. An interference mitigation module in a communication device, the module comprising:
an input configured to obtain a plurality of waveforms, the plurality of waveforms associated with a reception time;
a covariance estimation module configured to estimate a covariance matrix based on the plurality of waveforms;
a spatial filter module configured to determine a spatial filter based on the estimated covariance matrix; and
a controller configured to:
i) instruct the covariance estimation module to estimate a first covariance matrix based on a first plurality of waveforms,
ii) determine whether a packet is detected during the reception time or an automatic gain control setting changes during the reception time, and
iii) instruct the covariance estimation module to estimate a second covariance matrix based in part on said determination of whether a packet is detected during the reception time or an automatic gain control setting changes during the reception time.
2. The interference mitigation module of claim 1 , wherein operation i) is performed prior to operation ii).
3. The interference mitigation module of claim 1 , wherein the controller is further configured to iv) instruct the spatial filter module to determine a first spatial filter from one of the first estimated covariance matrix or the second estimated covariance matrix based in part on said determination of whether a packet is detected during the reception time or an automatic gain control setting changes during the reception time.
4. The interference mitigation module of claim 3 , wherein the controller is further configured to mitigate interference in a second plurality of waveforms by applying the first spatial filter.
5. The interference mitigation module of claim 1 , wherein determining whether a packet is detected during the reception time comprises determining whether a control signal is received between a time when the plurality of waveforms is obtained and a later time after the first covariance matrix is estimated.
6. The interference mitigation module of claim 1 , wherein the second covariance matrix is calculated based on new waveforms different from the first plurality of waveforms.
7. The interference mitigation module of claim 1 , wherein the controller is further configured to instruct the covariance estimation module to estimate a third covariance matrix based in part on detecting that a predetermined time has elapsed from detection of a stimulus event.
8. The interference mitigation module of claim 7 , wherein the stimulus event comprises a detection of a new waveform.
9. The interference mitigation module of claim 1 , wherein the controller is further configured to instruct the covariance estimation module to estimate a third covariance matrix based in part on detecting that a predetermined time has elapsed from detection of any stimulus event.
10. The interference mitigation module of claim 1 , wherein the controller is configured to periodically instruct the covariance estimation module to refine the estimated covariance matrix towards an estimate of interference and noise without a signal of interest.
11. The interference mitigation module of claim 1 , wherein the controller is further configured to instruct the covariance estimation module to estimate a third covariance matrix based in part on detecting that a prior estimation of covariance matrix was faulty.
12. An interference mitigation module in a communication device, the module comprising:
an input configured to obtain a plurality of waveforms, the plurality of waveforms associated with a reception time;
a covariance estimation module configured to estimate a covariance matrix based on the plurality of waveforms;
a spatial filter module configured to determine a spatial filter based on the estimated covariance matrix; and
a controller configured to:
i) instruct the covariance estimation module to estimate a first covariance matrix based on a first plurality of waveforms,
ii) determine whether a packet is detected during the reception time, wherein determining whether a packet is detected during the reception time comprises determining whether a control signal is received between a time when the plurality of waveforms is obtained and a later time after the covariance matrix is estimated, and
iii) instruct the covariance estimation module to estimate a second covariance matrix based in part on said determination of whether a packet is detected during the reception time.
13. The interference mitigation module of claim 12 , wherein operation i) is performed prior to operation ii).
14. The interference mitigation module of claim 12 , wherein the controller is further configured to iv) instruct the spatial filter module to determine a first spatial filter from one of the first estimated covariance matrix or the second estimated covariance matrix.
15. The interference mitigation module of claim 14 , wherein the controller is further configured to mitigate interference in a second plurality of waveforms by applying the first spatial filter.
16. The interference mitigation module of claim 12 , wherein the controller is further configured to determine whether an automatic gain control setting changes during the reception time.
17. An interference mitigation module in a communication device, the module comprising:
an input configured to obtain a plurality of waveforms, the plurality of waveforms associated with a reception time;
a covariance estimation module configured to estimate a covariance matrix based on the plurality of waveforms;
a spatial filter module configured to determine a spatial filter based on the estimated covariance matrix; and
a controller configured to:
i) determine whether a packet is detected during the reception time,
ii) determine whether an automatic gain control setting changes during the reception time, and
iii) instruct the covariance estimation module to estimate a first covariance matrix based on a first plurality of waveforms, wherein operation iii) is performed prior to at least one of operation i) or operation ii).
18. The interference mitigation module of claim 17 , wherein the controller is further configured to iv) instruct the spatial filter module to determine a first spatial filter from the first estimated covariance matrix.
19. The interference mitigation module of claim 17 , wherein determining whether a packet is detected during the reception time comprises determining whether a control signal is received between a time when the plurality of waveforms is obtained and a later time after the first covariance matrix is estimated.