Position location system architecture: messaging and ranging links

1. An indoor position location system, comprising:

a two-way narrowband messaging link transceiver operable to enable synchronization and ranging initialization between asset tags and access points of the indoor position location system; and

a two-way wideband ranging link transceiver operable to enable a ranging operation between the asset tags, the access points and a position location server of the indoor position location system, the position location server operable to determine a location of at least one of the asset tags according to the ranging operation.

2. The indoor position location system of claim 1 , in which the two-way narrowband messaging link transceiver is further operable to periodically broadcast a narrowband pilot signal to the asset tags.

3. The indoor position location system of claim 2 , in which the narrowband pilot signal comprises a known preamble and an access point identification field.

4. The indoor position location system of claim 2 , in which the narrowband pilot signal comprises a pseudo noise (PN) code to identify one of the access points.

5. The indoor position location system of claim 1 , in which the two-way narrowband messaging link transceiver is further operable to receive a reduced size packet from the at least one of the asset tags, and in which the two-way narrowband messaging link transceiver is further operable to transmit a frequency and/or timing error estimate of the at least one of the asset tags relative to one of the access points after a predetermined delay.

6. The indoor position location system of claim 1 , in which the two-way narrowband messaging link transceiver is further operable to communicate scheduling information to the asset tags, the scheduling information indicating when the two-way wideband ranging link transceiver transmits a wideband ranging preamble and a pseudo noise (PN) sequence of the wideband ranging preamble to initiate the ranging operation.

7. The indoor position location system of claim 1 , in which at least one of the asset tags is configured:

to periodically wake up to search for a narrowband pilot signal; and

to synchronize with at least one of the access points when the narrowband pilot signal is detected.

8. The indoor position location system of claim 7 , in which the narrowband pilot signal comprises a known preamble as an asset tag identification field.

9. The indoor position location system of claim 7 , in which the narrowband pilot signal comprises a pseudo noise (PN) code to identify the at least one asset tag.

10. The indoor position location system of claim 1 , further comprising:

a memory; and

at least one processor coupled to the memory and configured:

to periodically wake-up to search for a narrowband pilot signal; and

to synchronize with at least one of the access points when the narrowband pilot signal is detected.

11. The indoor position location system of claim 10 , in which the narrowband pilot signal comprises a known preamble as an access point identification field or a pseudo noise (PN) code to identify the access point.

12. A computer program product configured for the indoor position location system of claim 1 , the computer program product comprising:

a non-transitory computer-readable medium having non-transitory program code recorded thereon, the non-transitory program code comprising:

program code to periodically wake-up to search for a narrowband pilot signal; and

program code to synchronize with at least one of the access points when the narrowband pilot signal is detected.

13. The indoor position location system of claim 1 , further comprising:

means for periodically waking-up to search for a narrowband pilot signal; and

means for synchronizing with at least one of the access points when the narrowband pilot signal is detected.

14. A method within an indoor position location system, comprising:

transmitting, by an asset tag, a reduced size packet to an access point over a narrowband messaging link;

receiving, by the asset, a frequency and/or timing error estimate of the asset tag relative to the access point over the narrowband messaging link;

synchronizing, by the asset tag, with the access point according to the frequency and/or timing error estimate of the asset tag relative to the access point; and

initiating, by the asset, a ranging operation with the access point in response to receiving a wideband ranging signal received over a wideband ranging link.

15. The method of claim 14 , further comprising:

waking the asset tag according to received scheduling information regarding a wideband ranging preamble; and

performing the ranging operation when a pseudo noise (PN) sequence of the wideband ranging preamble is detected.

16. An asset tag of an indoor position location system, comprising:

a memory; and

at least one processor coupled to the memory and configured:

to transmit a reduced size packet to an access point over a narrowband messaging link transceiver;

to receive a frequency and/or timing error estimate of the asset tag relative to the access point over the narrowband messaging link transceiver;

to synchronize with the access point according to the frequency and/or timing error estimate of the asset tag relative to the access point; and

initiate a ranging operation with the access point in response to a wideband ranging signal received over a wideband ranging link transceiver.

17. The asset tag of claim 16 , in which the at least one processor is further configured:

to wake according to received scheduling information regarding a wideband ranging preamble; and

to performing a ranging operation when a pseudo noise (PN) sequence of the wideband ranging preamble is detected from the access point.

18. A computer program product configured for an asset tag of an indoor position location system, the computer program product comprising:

a non-transitory computer-readable medium having non-transitory program code recorded thereon, the non-transitory program code comprising:

program code to transmit a reduced size packet to an access point over a narrowband messaging link;

program code to receive a frequency and/or timing error estimate relative to the access point over the narrowband messaging link;

program code to synchronize with the access point according to the frequency and/or timing error estimate relative to the access point; and

program code to initiate a ranging operation with the access point in response to a wideband ranging signal received over a wideband ranging link.

19. An asset tag of an indoor position location system, comprising:

means for transmitting a reduced size packet to an access point over a narrowband messaging link;

means for receiving a frequency and/or timing error estimate of the asset tag relative to the access point over the narrowband messaging link;

means for synchronizing with the access point according to the frequency and/or timing error estimate of the asset tag relative to the access point; and

means for initiating a ranging operation with the access point in response to a wideband ranging signal received over a wideband ranging link.