System and method for a high throughput GSM location solution
A system and method for estimating a location of wireless devices transmitting signals on channels in a communications system having a plurality of nodes and a plurality of Location Measurement Units (“LMU”). A first plurality of signals from a first channel may be received by one or more of the plural LMUs and a second plurality of signals from a second channel may be received by one or more of the plural LMUs. The received first and second plural signals may be converted into first and second digital signals and then divided into first and second sets of frequency bins, the first and second sets of bins corresponding to the respective channel. Each of the divided signals may be correlated with one or more reference signals, and the correlated signals stored in a database for estimating a location of one or more wireless devices.
1. A method for estimating a location of wireless devices transmitting signals on channels in a communications system having a plurality of nodes and a plurality of Location Measurement Units (“LMU”) comprising the steps of:
(a) receiving a first plurality of signals from a first channel by one or more of the plural LMUs;
(b) receiving a second plurality of signals from a second channel by one or more of the plural LMUs;
(c) converting the received first and second plural signals into first and second digital signals;
(d) dividing the first and second digital signals into first and second sets of frequency bins, the first and second sets of bins corresponding to the respective channel;
(e) correlating each of the divided signals with one or more reference signals;
(f) storing correlated signals in a database for estimating a location of one or more wireless devices
(g) receiving tipping information by one or more of the LMUs;
(h) retrieving stored correlated signals from the database matching data in the tipping information;
(i) non-coherently adding the retrieved signals;
(j) determining time of arrival (“TOA”) information as a function of peak or peak quality of the added signals; and
(k) estimating a location of a wireless device as a function of the determined TOA information.
2. The method of claim 1 wherein the one or more reference signals is one or more training sequences or any known reference signals.
3. The method of claim 1 wherein the step of dividing further comprises:
(i) windowing the first and second digital signals; and
(ii) determining an inverse fast Fourier transform (“IFFT”) of each of the windowed signals.
4. The method of claim 3 wherein the windowing is performed by a finite impulse response (“FIR”) filter.
5. The method of claim 3 wherein the steps of windowing of the first and second digital signals and determining are performed in parallel.
6. The method of claim 3 wherein the steps of windowing of the first and second digital signals and determining are performed in series.
7. The method of claim 1 further comprising the step of:
(g) estimating a location of the wireless device as a function of the stored correlated signals.
8. The method of claim 7 further comprising the step of receiving tipping information by one or more of the LMUs wherein data used for the stored correlated signals was received prior to receipt of the tipping information.
9. The method of claim 8 wherein the tipping information is selected from the group consisting of: frequencies or channel numbers of transmissions from the wireless device, approximate time of one or more transmissions from the wireless device, training sequences utilized in one or more transmissions from the wireless device, and combinations thereof.
10. The method of claim 7 wherein the wireless device has ceased transmitting signals on its respective channel and the step of estimating a location occurs after the cease of transmission.
11. The method of claim 1 wherein the step of correlating further comprises continuously correlating each of the divided signals with eight training sequences.
12. The method of claim 1 wherein the first and second digital signals are divided serially.
13. The method of claim 1 wherein the first and second digital signals are divided in parallel.