Method and apparatus for compressing GPS satellite broadcast message information

• US 6,429,811 B1
• Filed: 02/15/2000
• Issued: 08/06/2002
• Est. Priority Date: 02/15/2000
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: King, Thomas M., Geier, George J., Zhao, Yilin
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US09/504,152
• Time in Patent Office: 903 Days
• Field of Search: 342/357.09, 342/357.06, 342/357.1, 701/213, 701/214, 701/215
• US Class Current: 342/357.66
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04B 1/66 for reducing bandwidth of signals; for improving efficiency of transmission H04B1/68 takes precedence

Abstract

An assisted global positioning satellite (Assisted GPS) system has a GPS reference network node (260) that collects GPS satellite broadcast messages and prepares separate GPS assistance messages to be modulated by a base transceiver station (BTS) (202) on a cellular carrier signal (201) and sent to single or multiple handset (204). In a first preferred embodiment, instead of the handset (204) receiving standard ephemeris and clock correction data elements in a GPS assistance message, a compressed GPS assistance message containing XYZ information contains a GPS satellite'"'"'s coordinate position modified according to the satellite clock correction. In a second preferred embodiment, there is a first type of compressed GPS assistance message containing subframe 1, 2, 3 data of a GPS satellite broadcast message and a second type of compressed GPS assistance message containing subframe 4, 5 data of a GPS satellite broadcast message. The compressed GPS assistance messages according to the second preferred embodiment lack redundant or predictable information in order to reduce the size of the compressed GPS assistance message. The first type can be updated at a different rate than the second type in order to reduce the traffic and yet keep the handset (204) up to date.

Claims

1. A GPS assistance message for wireless transmission from infrastructure to a handset comprising:

subframe 1 compressed data from subframe 1 of a received global positioning system (GPS) satellite broadcast navigation message;

subframe 2 compressed data from subframe 2 of the received GPS satellite broadcast navigation message;

subframe 3 compressed data from subframe 3 of the received GPS satellite broadcast navigation message; and

time-tagged time of transmission information.

2. A GPS assistance message according to claim 1, wherein said subframe 1 compressed data comprises:

bits of said subframe 1 of the received GPS satellite broadcast navigation message minus a preamble, minus a subframe identification, and minus parity bits.

3. A GPS assistance message according to claim 1, wherein said subframe 2 compressed data comprises:

bits of said subframe 2 of the received GPS satellite broadcast navigation message minus a preamble, minus a subframe identification, minus a handover word (HOW word), minus a telemetry (TLM) word, minus an issue of data ephemeris, and minus parity bits.

4. A GPS assistance message according to claim 1, wherein said subframe 3 compressed data comprises:

bits of said subframe 3 of the received GPS satellite broadcast navigation message minus a preamble, minus a subframe identification, minus a HOW word, minus a TLM word, minus an IODE, and minus parity bits.

5. A GPS assistance message according to claim 1, wherein said time-tagged time of transmission information is measured from the time the GPS assistance message is sent from the infrastructure to the said handset to the time indicated at the start of a first bit in said subframe 1 of the received GPS satellite broadcast navigation message.

6. A GPS assistance message for wireless transmission from infrastructure to a handset comprising:

subframe 4 compressed data from subframe 4 of a received global positioning system (GPS) satellite broadcast navigation message;

subframe 5 compressed data from subframe 5 of the GPS satellite broadcast navigation message; and

time-tagged time of transmission information.

7. A GPS assistance message according to claim 6, wherein said subframe 4 compressed data comprises:

bits of said subframe 4 of the received GPS satellite broadcast navigation message minus, a TLM word, minus a HOW word, minus a satellite identification, and minus parity bits.

8. A GPS assistance message according to claim 6, wherein said subframe 5 compressed data comprises:

bits of said subframe 5 of the received GPS satellite broadcast navigation message minus, minus a HOW word, minus a satellite identification, minus a TLM word, and minus parity bits.

9. A GPS assistance message according to claim 6, wherein said time-tagged time of transmission information is measured from the time the GPS assistance message is sent to from the infrastructure to the said handset to the time indicated at the start of a first bit in said subframe 4 of the received GPS satellite broadcast navigation message.

10. A GPS assistance message for wireless transmission from infrastructure to a handset comprising:

an initial time indicator to indicate an initial time;

a satellite identification of a global positioning system (GPS) satellite;

a first coordinate for the position of the GPS satellite at the initial time;

a second coordinate for the position of the GPS satellite at the initial time; and

a third coordinate for the position of the GPS satellite at the initial time.

11. A GPS assistance message according to claim 10 wherein the first coordinate, the second coordinate, and the third coordinate are X,Y, and Z Cartesian coordinates.

12. A GPS assistance message according to claim 10 wherein the first coordinate, the second coordinate, and the third coordinate are θ

, φ

, and r spherical coordinates.

13. A GPS assistance message according to claim 10 wherein the first coordinate, the second coordinate, and the third coordinate are modified based on satellite clock correction data from the GPS satellite.

14. A GPS assistance message according to claim 10 further comprising:

a fourth coordinate for the position of the GPS satellite at the initial time plus a predetermined time interval;

a fifth coordinate for the position of the GPS satellite at the initial time plus the predetermined time interval (Δ

T); and

a sixth coordinate for the position of the GPS satellite at the initial time plus the predetermined time interval (Δ

T).

15. A GPS assistance message according to claim 14 further comprising:

a seventh coordinate for the position of the GPS satellite at the initial time plus twice the predetermined time interval (2Δ

T);

a eighth coordinate for the position of the GPS satellite at the initial time plus twice the predetermined time interval (2Δ

T); and

a ninth coordinate for the position of the GPS satellite at the initial time plus twice the predetermined time interval (2Δ

T).

16. A method for transmitting compressed GPS assistance messages comprising the steps of:

transmitting compressed GPS assistance messages containing subframe 1, 2, 3 data at a first transmission rate; and

transmitting compressed GPS assistance messages containing subframe 4, 5 data at a second transmission rate.

17. A method according to claim 16 wherein the step of transmitting compressed GPS assistance messages containing subframe 1, 2, 3 data at a first transmission rate comprises dynamically adjusting the first transmission rate.

18. A method according to claim 17 wherein the step of dynamically adjusting the first transmission rate depends upon infrastructure usage patterns, time, or traffic load.

19. A method according to claim 16 wherein the step of transmitting compressed GPS assistance messages containing subframe 4, 5 data at a second transmission rate comprises dynamically adjusting the second transmission rate.

20. A method according to claim 16 wherein the first transmission rate is higher than the second transmission rate.

21. A method according to claim 16 further comprising the step of:

transmitting an acquisition assist message at a third transmission rate.

22. A method according to claim 21 wherein the step of transmitting an acquisition assist message at a third transmission rate comprises dynamically adjusting the third transmission rate.

23. A method according to claim 16 further comprising the step of:

transmitting a differential global positioning system (DGPS) correction message at a fourth transmission rate.

24. A method according to claim 23 wherein the step of transmitting a DGPS correction message at a fourth transmission rate comprises dynamically adjusting the fourth transmission rate.

25. A global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

subframe 1 compressed data from subframe 1 of a global positioning system satellite broadcast navigation message;

subframe 2 compressed data from subframe 2 of the global positioning system satellite broadcast navigation message; and

subframe 3 compressed data from subframe 3 of the received global positioning system satellite broadcast navigation message.

26. A GPS assistance message according to claim 25, wherein said subframe 1 compressed data comprises bits of said subframe 1 of the global positioning system satellite broadcast navigation message minus a HOW word, minus a TLM word, minus a week number, and minus parity bits.

27. A GPS assistance message according to claim 25, wherein said subframe 2 compressed data comprises bits of said subframe 2 of the global positioning system satellite broadcast navigation message minus a HOW word, minus a TLM word, minus an issue of data ephemeris, and minus parity bits.

28. A GPS assistance message according to claim 25, wherein said subframe 3 compressed data comprises bits of said subframe 3 of the global positioning system satellite broadcast navigation message minus a HOW word, minus a TLM word, minus an issue of data ephemeris, and minus parity bits.

29. A global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

subframe 4 compressed data from subframe 4 of a global positioning system satellite broadcast navigation message; and

subframe 5 compressed data from subframe 5 of the global positioning system satellite broadcast navigation message.

30. A GPS assistance message according to claim 29, wherein said subframe 4 compressed data comprises bits of said subframe 4 of the global positioning system satellite broadcast navigation message minus ionospheric delay elements, minus UTC offsets, minus a TLM word, minus a HOW word, minus a Data ID, and minus parity bits.

31. A GPS assistance message according to claim 29, wherein said subframe 5 compressed data comprises bits of said subframe 5 of the GPS satellite broadcast navigation message minus a HOW word, minus a TLM word, minus a Data ID, and minus parity bits.

32. A global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

subframe 4 compressed data from subframe 4 of a global positioning system satellite broadcast navigation message,

the subframe 4 compressed data includes universal time coordinate (UTC) offsets, minus parity bits.

33. A global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

subframe 4 compressed data from subframe 4 of a global positioning system (GPS) satellite broadcast navigation message,

the subframe 4 compressed data includes ionospheric delay elements, minus parity bits.

34. A global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

subframe compressed data from a global positioning system satellite broadcast navigation message including a TLM word, minus a preamble and minus parity bits.

35. A method for generating a global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

compressing subframe 1 data of a global positioning system satellite broadcast navigation message;

compressing subframe 2 data of the global positioning system satellite broadcast navigation message; and

compressing subframe 3 data of the received global positioning system satellite broadcast navigation message.

36. A method according to claim 35, compressing said subframe 1 data of the global positioning system satellite broadcast navigation message by removing a HOW word, removing a TLM word, removing a week number, and removing parity bits from said subframe 1 compressed data.

37. A method according to claim 35, compressing said subframe 2 data of the global positioning system satellite broadcast navigation message by removing a HOW word, removing a TLM word, removing an issue of data ephemeris, and removing parity bits from said subframe 2 compressed data.

38. A method according to claim 35, compressing said subframe 3 data of the global positioning system satellite broadcast navigation message by removing a HOW word, removing a TLM word, removing an issue of data ephemeris, and removing parity bits from said subframe 3 compressed data.

39. A method for generating a global positioning system (GPS) assistance message for wireless transmission from infrastructure to a handset, comprising:

compressing subframe 4 data of a global positioning system satellite broadcast navigation message;

compressing subframe 5 data of the global positioning system satellite broadcast navigation message.

40. A method according to claim 39, compressing said subframe 4 data of the global positioning system satellite broadcast navigation message by removing ionospheric delay elements, UTC offsets, a TLM word, a HOW word, a Data ID, and parity bits from said subframe 4 data.

41. A method according to claim 39, compressing said subframe 5 data of the global positioning system satellite broadcast navigation message by removing a HOW word, a TLM word, a Data ID, and parity bits said subframe 5 data.