Method, apparatus and system for synchronizing a cellular communication system to GPS time

• US 20030109264A1
• Filed: 12/12/2001
• Published: 06/12/2003
• Est. Priority Date: 12/12/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Nokia Corporation
• Inventors: Valio, Harri, Syrjarinne, Jari
• Granted Patent: US 6,748,202 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A ranging receiver (10) including a cellular module (11), for providing time according to a positioning system to enable synchronizing a wireless system to the positioning system. The ranging receiver (10) includes both the cellular module (11) and a main module (12) that provides ranging receiver functionality. When the cellular module (11) receives a time-stamped frame from the wireless system, it sends a trigger signal over a special hardware path to the main module (12), which then relates the time of trigger receipt to time according to the positioning system by calculating a position-velocity-time (PVT) solution, using a local clock (18) to get the difference in time between receipt of the trigger and the instant to which the PVT solution applies, and then communicates to the cellular module (11) when it received the trigger, according to positioning system time.

Claims

1. An apparatus (10), comprising:

a) a cellular module (11), responsive to a portion of a downlink frame signal; and

b) a main module (12), responsive to ranging signals from beacons (27) of a positioning system in which time is kept according to the predetermined time reference;

the apparatus characterized in that;

the cellular module (11) provides a trigger signal indicating the arrival of the portion of the downlink frame signal, and is further responsive to a signal indicating information for relating the instant at which the trigger signal is provided to a time value according to a predetermined time reference; and

the main module provides the signal indicating the information for relating the instant at which the trigger signal is provided by the cellular module (11) to a time value according to the predetermined time reference;

wherein the triggering signal is provided over a connection (29) between the cellular module (11) and the main module (12) constructed so that any delay between sending and receiving the triggering signal is known by the apparatus (10).

2. The apparatus of claim 1, further characterized by the main module (12) comprising a timing register (19) and a local clock (18), the timing register (19) responding to the trigger signal by reading the local clock to determine a local trigger time and holding the local trigger time until being reset or until another trigger signal is issued by the cellular module (11).

3. The apparatus of claim 2, further characterized in that the main module (12) further comprises a main processor (21), responsive to the ranging signals and to the value stored in the timing register (19) and to the local time as indicated by the local clock (18), for determining a navigation solution including a preliminary time value according to the predetermined time reference, the preliminary time value being a time value for the instant of time for which the navigation solution is determined, and for adjusting the preliminary time value by the difference in time according to the local clock (18) when the timing register (19) was triggered and when the navigation solution was determined, thereby providing the time value, according to the predetermined time reference, for the instant when the timing register (19) was triggered.

4. The apparatus of claim 1, further characterized in that the apparatus further comprises a time slot counter, and the trigger pulse is provided when the time slot counter indicates a new time slot.

5. The apparatus of claim 1, further characterized in that the apparatus further comprises a data bit counter, and wherein the trigger pulse is provided when the data bit counter indicates a new data bit.

6. The apparatus of claim 1, further characterized in that the the main module (12) is a global positioning system (GPS) module providing functionality for operation as a GPS receiver.

7. The apparatus of claim 1, further characterized in that the cellular module (11) provides to a serving base station the information for relating to a time value according to a predetermined time reference, the instant at which the trigger signal is provided.

8. The apparatus of claim 7, further characterized in that the main module (12) also provides a position for the instant when the trigger signal was received by the main module (12), and the cellular module (11) is responsive to the position, and provides the position to the serving base station.

9. A system, comprising an apparatus according to claim 1, and further comprising a cellular base station (24), for providing the cellular frame.

10. A system, comprising an apparatus according to claim 1, and further comprising the beacons (27) of the positioning system that provide the ranging signals.

11. A method for having a ranging receiver (10), able to be used with a positioning system and including a cellular module (12) and a main module (11), provide information to a serving base station of use in enabling the serving base station to synchronize to time according to the positioning system, the method characterized by:

a) a step (32) in which the cellular module (11) detects a portion of a time-stamped frame and applies a trigger signal to a connection linking the cellular module (11) to the main module (12), a connection such that any delay between applying a signal and receiving the signal is either negligible or can be determined; and

b) a step (40) in which the main module (12) sends to the cellular module (11) a time value according to the positioning system for the instant when the main module (12) received the trigger signal, based on performing a navigation solution yielding a time value for an instant of time able to be related to the instant of time when the trigger signal was received using a local clock (20) accessible to the main module (12).

12. The method of claim 11, further characterized by a step (37) in which the main module (12) determines the difference in time between the time for which the navigation solution was obtained and the time when the trigger signal arrived at the main module (12), based on using a local clock (18) and a timing register (19) latchable by the trigger signal so as to hold a time value according to the local clock (18) for when a trigger signal arrives.

13. The method of claim 11, further characterized in that in the step (40) in which the main module (12) sends to the cellular module (11) a time value, the main module (12) also sends the cellular module (11) a signal indicating information about the position of the ranging receiver.