Method and system for estimation of mobile station velocity in a cellular system based on geographical data
A system and method for estimating velocity of a mobile station in a wireless communication system using time-frequency signal processing and a geographical database. The geographical database is used for prediction of ray trajectory and ray power to provide an estimate of propagation delay associated with database points.
1. A system for estimating velocity of a mobile station comprising:
a mobile station capable of transmitting signals;
a fixed station capable of receiving signals transmitted by at least said mobile station;
a geographical database, comprising descriptive information about a geographical area;
a processor operably connected to said fixed station and said geographical database, to
(a) process a signal sent from said mobile station to said fixed station with data from said geographical database to determine an estimate of velocity of said mobile station;
(b) further process said signal using time-frequency signal processing;
(c) further process said signal using ray tracing;
(d) further process said signal to resolve said signal into component parts and identify scatterers and scatterers' contributions to said components;
(e) further process said signal to calculate Doppler estimates of rays corresponding to scatterers;
(f) further process said signal using matched filtering of said Doppler estimate and of a shifted Doppler estimate;
(g) determine said shifted Doppler estimate using a range gate; and
(h) further process said signal to calculate a best fit of biases to a Doppler spectra, where said Doppler spectra is calculated from said time-frequency analysis using said ray tracing to identify said scatterers, and where said biases are calculated from said Doppler estimate.
2. The system of claim 1 , wherein said mobile station further comprises an antenna.
3. The system of claim 1 , wherein said processor is located within said fixed station.
4. The system of claim 1 , wherein said processor further uses said delayed Doppler estimate and said geographical database to locate scatterers on a map.
5. A system for estimating velocity of a mobile station comprising:
a mobile station capable of transmitting signals;
a fixed station capable of receiving signals transmitted by at least said mobile station;
a geographical database, comprising descriptive information about a geographical area;
a processor operably connected to said fixed station and said geographical database, to
(a) process a signal sent from said mobile station to said fixed station with data from said geographical database to determine an estimate of velocity of said mobile station;
(b) further process said signal using time-frequency signal processing;
(c) further process said signal using ray tracing;
(d) further process said signal to resolve said signal into component parts and identify scatterers and scatterers' contributions to said components;
(e) further process said signal to calculate Doppler estimates of rays corresponding to scatterers;
(f) further process said signal using matched filtering of said Doppler estimate and of a shifted Doppler estimate;
(g) determine said shifted Doppler estimate using a range gate;
wherein said processor further processes said signal to determine a weighted least squares estimator, where said weighted least squares estimator is calculated from the velocity and direction of each said scatterer in each said range gate, an estimate of amplitude, phase and bias, and an estimate of standard deviation of errors of said amplitude, phase and bias.
6. The system of claim 1 , wherein said processor further processes said signal using a predicted delay profile and a Doppler spread pattern, where said Doppler spread pattern is calculated from a Doppler shift of said signal.