Method and apparatus for generating time of arrival estimates for use in determining a location

A processor unit for use in a wireless communication device, coupled to a receiver, which generates a time of arrival estimate for each of a group of base sites, said processor unit comprising:

• a processor;
• an interface circuitry coupled to said processor and the receiver for configuring the receiver to receive signals corresponding to the group of base sites, and for receiving a plurality of data bursts;
• a storage unit coupled to said processor for storing sampling data of the plurality of data bursts and one or more sets of instructions for execution by the processor including
• prestored instructions for receiving a plurality of data bursts from a group of base sites during a burst collection period and determining a time of arrival value for each of the data bursts,
• prestored instructions for selecting the time of arrival values, which more closely correspond to a line of sight path and estimating a drift value of a reference clock for each of the base sites from the selected time of arrival values, and
• prestored instructions for generating a time of arrival estimate for each of the base sites corresponding to a particular time during the burst collection period.

A wireless communication device comprising:

• an antenna;
• a receiver coupled to said antenna;
• a processor unit coupled to said receiver including a processor;
• an interface circuitry coupled to said processor and the receiver for configuring the receiver to receive signals corresponding to the group of base sites, and for receiving a plurality of data bursts;
• a storage unit coupled to said processor for storing sampling data of the plurality of data bursts and one or more sets of instructions for execution by the processor including
• prestored instructions for receiving a plurality of data bursts from a group of base sites during a burst collection period and determining a time of arrival value for each of the data bursts,
• prestored instructions for selecting the time of arrival values, which more closely correspond to a line of sight path and estimating a drift value of a reference clock for each of the base sites from the selected time of arrival values, and
• prestored instructions for generating a time of arrival estimate for each of the base sites corresponding to a particular time during the burst collection period.

A processor unit for use in a wireless communication device, coupled to a receiver, which generates a time of arrival estimate for each of a group of base sites, said processor unit comprising:

• a sampling circuit for producing multiple sampling points from a received signal;
• a correlator coupled to the sampling circuit for correlating the sampling points with a corresponding predetermined data pattern and determining a time of arrival value for each data burst;
• a discriminator circuit coupled to the correlator for selecting the time of arrival values, which most closely correspond to a line of sight path;
• a drift estimator coupled to the discriminator circuit for estimating an estimated drift value of a reference clock for each of the base stations from the selected time of arrival values;
• a time of arrival estimator coupled to the drift estimator for estimating a time of arrival value from the estimated drift calculation for each of the base stations for a selected substantially consistent point in time;
• and
• a variance calculator coupled to the time of arrival estimator for computing a variance value corresponding to the accumulated degree of deviation of the time of arrival value determined by the time of arrival estimator.