Multi-path mitigation in tracking objects using compressed RF data
A split architecture is disclosed for determining the location of a wireless device in a heterogeneous wireless communications environment. A detector within the device or another component of the environment receives signals including parameters for a localization signal of the device. The parameters describe known in advance signals within the signals. Additional metadata including each frame start of the signals and assistance data and auxiliary information are also received. The known in advance signals are detected based on the parameters of the localization signal. Samples extracted from the known in advance signals are then processed and compressed and sent with other collect data to a locate server remote from the detector. The location server uses that information as well as similar information about the environment to calculate the location of the device, as well as perform tracking and navigation of the device, and report such results to the environment.
1. A method at a detector for preparing RF data for use in determining a location of a wireless mobile device in a wireless communications environment, comprising:
receiving signals from one or more receive channels that include parameters for a localization signal of the wireless mobile device, the parameters being associated with known in advance signals within the signals;
receiving metadata related to the signals;
detecting the known in advance signals from each receive channel among the one or more receive channels based on the parameters of the localization signal;
buffering a plurality of samples in a digital format extracted from the known in advance signals;
extracting data necessary for determining the location from the plurality of samples; and
sending the extracted data, the parameters of the localization signal, and the metadata to a locate server physically remote from the detector for determination of the location.
2. The method of claim 1 , wherein detecting the known in advance signals includes extracting the plurality of samples in the digital format from the known in advance signals.
3. The method of claim 2 , wherein extracting the plurality of samples includes comprising collecting a number of the samples in the digital format per antenna at a receiver and collecting a signal identification corresponding to each sample in the digital format.
4. The method of claim 1 , wherein the extracted data only represents the known in advance signals that will be used to determine the location.
5. The method of claim 1 , wherein extracting the data includes pre-processing the data necessary for determining the location from the plurality of samples.
6. The method of claim 5 , wherein pre-processing the data includes making a subset of data samples from each sample in the digital format available in a frame of a GPS/GNSS navigation message.
7. The method of claim 5 , wherein the metadata includes assistance data, and wherein pre-processing the data includes carrying the assistance data in a remainder of a navigation message.
8. The method of claim 7 , wherein the assistance data includes one or more of a reference time, a reference location, a satellite ephemeris, clock corrections, Ionospheric Models, Earth Orientation Parameters, GNSS Time Offsets, an Acquisition Assistance, an Almanac, UTC Models, or a combination thereof.
9. The method of claim 5 , wherein extracting the data includes compressing the extracted data and the pre-processed data.
10. The method of claim 9 , wherein pre-processing the data reduces the data size before sending the compressed data to the locate server.
11. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes utilizing one or more of a A-law compounding algorithm and a U-law compounding algorithm.
12. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes reducing a sample size of each digital sample size to a smaller number of bits.
13. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes employing a coherent compression scheme wherein a size of a resultant data sample to be sent to the locate server is reduced to a non-zero portion of a cross-correlation output of the known in advance signals, and integrating a number of uniquely identified known in advance signals among the known in advance signals.
14. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes employing a compression scheme including matched filtering of the known in advance signals combined with carrier frequency offset (CFO) processing per each uniquely identified known in advance signal among the known in advance signals.
15. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes matched filtering of only known in advance signals used for determination of the location.
16. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes calculating singular-value decomposition (SVD) principle eigenvalues of a matrix formed from one or more of the plurality of samples in digital format.
17. The method of claim 9 , wherein compressing the extracted data and the pre-processed data includes performing additional pre-processing based on a tradeoff between a computational load resources required and a reduction of communication bandwidth with the locate server.
18. An apparatus comprising:
a detector;
one or more receivers;
one or more memory; and
one or more processors coupled to the one or more memory and the one or more receivers, the one or more processors configured to:
receive signals via the one or more receivers, the signals including parameters for a localization signal of a wireless mobile device, the parameters being associated with known in advance signals within the signals;
receive metadata related to the signals;
detect the known in advance signals from each receive channel among the one or more receive channels based on the parameters of the localization signal;
buffer a plurality of samples in a digital format extracted from the known in advance signals;
extract data necessary for determining a location of the wireless mobile device from the plurality of samples; and
send the extracted data, the parameters of the localization signal, and the metadata to a locate server physically remote from the detector for determination of the location.
19. The apparatus of claim 18 , wherein the extraction of the data includes pre-processing the data necessary for determining the location from the plurality of samples.
20. A non-transitory computer-readable apparatus comprising a storage medium, the storage medium comprising a plurality of instructions configured to, when executed by one or more processors of a detector, cause a networked apparatus to:
receive signals via one or more receive channel, the signals including parameters for a localization signal of a wireless mobile device, the parameters being associated with known in advance signals within the signals;
receive metadata related to the signals;
detect the known in advance signals from each receive channel among the one or more receive channels based on the parameters of the localization signal;
buffer a plurality of samples in a digital format extracted from the known in advance signals;
extract data necessary for determining a location of the wireless mobile device from the plurality of samples; and
send the extracted data, the parameters of the localization signal, and the metadata to a locate server physically remote from the detector for determination of the location.