Wireless terminal and method for managing the receipt of position reference singals for use in determining a location

1. A method in a wireless terminal for use in a location determination approach using time of arrival estimates between the wireless terminal and a plurality of base stations in a cellular network, the method comprising:

receiving assistance data from a serving base station for use in receiving a position reference signal used to determine a time of arrival of respective position reference signals from the plurality of base stations relative to a time reference, wherein the assistance data includes a list of base stations, each base station included in the list to be one of used or excluded from use as part of the plurality of base stations for receiving the position reference signal and determining the time of arrival estimate for the received position reference signal, and wherein the assistance information includes a white list of base stations, which includes base stations other than the serving base station to be used for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, where the white list includes base stations in addition to base stations from other received lists of neighbor base stations that are received as part of a message from the serving base station;

receiving the position reference signal for each of the plurality of base stations, where for each of the plurality of base stations a time of arrival estimate is determined for each of the respective received position reference signals; and

forwarding the time of arrival estimates for each of the plurality of base stations to a location determination entity.

2. A method in accordance with claim 1 , wherein the white list includes base stations which are unavailable to the wireless terminal for establishing a communication connection, but are available for receiving a position reference signal therefrom.

3. A method in accordance with claim 1 , wherein the message from the serving base station having a neighbor list is part of a message from the serving base station used for mobility measurements.

4. A method in accordance with claim 1 , wherein the assistance information includes a black list of base stations, which includes base stations to be excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal.

5. A method in accordance with claim 4 , wherein the black list includes base stations to be subtracted from other received lists of neighbor base stations.

6. A method in accordance with claim 1 , wherein the position reference signal is a signal dedicated to determining a time of arrival estimate at a wireless terminal from a base station for use in determining the location of the wireless terminal.

7. A method in accordance with claim 1 , wherein the location determination entity is a location server.

8. A method in accordance with claim 1 , wherein the position reference signal is encoded as part of an OFDM downlink data channel.

9. A method in accordance with claim 1 , wherein the cellular network is a Long Term Evolution (LTE) cellular network.

10. A method in accordance with claim 1 , wherein the wireless terminal is a radio telephone.

11. A method in accordance with claim 1 , further comprising determining a timing offset of system clocks used to support the radio transmission of a wireless signal relative to a first base station and a second base station;

wherein upon determining a timing offset relative to the first base station and the second base station, adding the first base station to the white list for one or more wireless terminals where the second base station is the serving base station, where the white list is used to identify for the one or more wireless terminals the non-serving base stations to be used for receiving a position reference signal for determining a time of arrival estimate of a signal received from the non-serving base station.

12. A method in accordance with claim 1 , wherein the list of base stations included as part of the assistance data is transmitted as part of a system information broadcast signal.

13. A method in accordance with claim 1 , wherein the list of base stations included as part of the assistance data is transmitted as part of a radio resource control message communicated to one or more wireless terminals.

14. A wireless terminal for use in a cellular wireless communication network having multiple base stations including a serving base station, the wireless terminal comprising:

a transceiver including a transmitter and a receiver;

a timer for maintaining a local time reference; and

a controller coupled to the transceiver and the timer, the controller including:

a location determination module adapted for managing the receipt of assistance data from the serving base station for determining a timing relationship between the time reference for each of a plurality of base stations and the local time reference, wherein the assistance data includes a list of base stations, each base station included in the list to be one of used or excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, and wherein the assistance information includes a white list of base stations, which includes base stations other than the serving base station to be used for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, where the white list includes base stations in addition to base stations from other received lists of neighbor base stations that are received as part of a message from the serving base station; managing the receipt of a plurality of respective position reference signals, via the transceiver, the position reference signals each having a time of receipt within the wireless terminal; calculating a time of arrival estimate for each of the received position reference signals from the determined timing relationship and received position reference signal for each of the plurality of base stations; and managing the transmission of the time of arrival estimate for each of the plurality of base stations to a location determination entity.

15. A wireless terminal in accordance with claim 14 , further comprising a memory storage unit coupled to the controller, which is adapted for storing received assistance data.

16. A wireless terminal in accordance with claim 15 , wherein the memory storage unit is further adapted for storing one or more sets of prestored instructions for execution by the controller, including a set of prestored instructions for the location determination module.

17. A method in a wireless terminal for use in a location determination approach using time of arrival estimates between the wireless terminal and a plurality of base stations in a cellular network, the method comprising:

receiving assistance data from a serving base station for use in receiving a position reference signal used to determine a time of arrival of respective position reference signals from the plurality of base stations relative to a time reference, wherein the assistance data includes a list of base stations, each base station included in the list to be one of used or excluded from use as part of the plurality of base stations for receiving the position reference signal and determining the time of arrival estimate for the received position reference signal, and wherein the assistance information includes a black list of base stations, which includes base stations to be excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, where the black list includes base stations to be subtracted from other received lists of neighbor base stations that are received as part of a message from the serving base station;

receiving the position reference signal for each of the plurality of base stations, where for each of the plurality of base stations a time of arrival estimate is determined for each of the respective received position reference signals; and

forwarding the time of arrival estimates for each of the plurality of base stations to a location determination entity.

18. A method in accordance with claim 17 , wherein the assistance information includes a white list of base stations, which includes base stations to be used for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal.

19. A method in accordance with claim 18 , wherein the white list includes base stations in addition to base stations from other received lists of neighbor base stations.

20. A method in accordance with claim 17 , wherein the list of base stations included as part of the assistance information includes a list of communication cell identifiers, which includes identifiers for communication cells to be one of used or excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal.

21. A method in accordance with claim 20 , wherein the communication cells to be excluded includes one or more respective subsets of one or more sets of communication cells having signals that originate from the same location.

22. A method in accordance with claim 17 , further comprising determining a timing offset of system clocks used to support the radio transmission of a wireless signal relative to a first base station and a second base station;

wherein upon determining a timing offset relative to the first base station and the second base station, removing the first base station from the black list for one or more wireless terminals where the second base station is the serving base station, where the black list is used to identify for the one or more wireless terminals the non-serving base stations not to be used for receiving a position reference signal for determining a time of arrival estimate of a signal received from the non-serving base station.

23. A wireless terminal for use in a cellular wireless communication network having multiple base stations including a serving base station, the wireless terminal comprising:

a transceiver including a transmitter and a receiver;

a timer for maintaining a local time reference; and

a controller coupled to the transceiver and the timer, the controller including:

a location determination module adapted for managing the receipt of assistance data from the serving base station for determining a timing relationship between the time reference for each of a plurality of base stations and the local time reference, wherein the assistance data includes a list of base stations, each base station included in the list to be one of used or excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, and wherein the assistance information includes a black list of base stations, which includes base stations to be excluded from use for receiving a position reference signal and determining a time of arrival estimate for the received position reference signal, where the black list includes base stations to be subtracted from other received lists of neighbor base stations that are received as part of a message from the serving base station; managing the receipt of a plurality of respective position reference signals, via the transceiver, the position reference signals each having a time of receipt within the wireless terminal; calculating a time of arrival estimate for each of the received position reference signals from the determined timing relationship and received position reference signal for each of the plurality of base stations; and managing the transmission of the time of arrival estimate for each of the plurality of base stations to a location determination entity.