Method and apparatus for compressing GPS satellite broadcast message information

• US 7,720,601 B2
• Filed: 08/05/2002
• Issued: 05/18/2010
• Est. Priority Date: 02/15/2000
• Status: Active Grant

• 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:
  US10/212,617
• Publication Number:
  US 20030011513A1
• Time in Patent Office: 2,843 Days
• Field of Search: 701213-215, 342/357.06, 342/357.1, 342/357.09
• US Class Current: 701/213
• 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 method for transmitting global positioning system (GPS) assistance information from communications infrastructure to a wireless communications handset, comprising:

transmitting, from the communications infrastructure, compressed GPS subframe 1, 2, 3 data in a GPS assistance message; and

transmitting, from the communications infrastructure, compressed GPS subframe 4, 5 data in a separate GPS assistance message.

2. A method for transmitting satellite positioning system assistance messages from communications infrastructure to a mobile wireless communications handset, the method comprising:

transmitting, from the communications infrastructure, a satellite positioning system assistance message containing first compressed subframe data at a first transmission rate; and

transmitting, from the communications infrastructure, a compressed satellite positioning system assistance message containing second compressed subframe data.

3. A method according to claim 2, transmitting the compressed satellite positioning system assistance message containing second compressed subframe data at a second transmission rate.

4. The method according to claim 2, further comprising transmitting estimated handset position and satellite positioning system reference time at one of the first transmission rate and at a third transmission rate.

5. A method according to claim 2, transmitting a differential satellite positioning system (DSPS) correction message at a fourth transmission rate, wherein transmitting the DSPS correction message at a fourth transmission rate comprises dynamically adjusting the fourth transmission rate.

6. A method for transmitting satellite positioning system assistance messages from communications infrastructure to a wireless communications handset, the method comprising:

transmitting, from the communications infrastructure, a first satellite positioning system message at a first transmission rate,

the first satellite positioning system message including at least one of location, time, DGPS, ephemeris, almanac, ionispheric, and time offset information;

transmitting, from the communications infrastructure, a second satellite positioning system message at a second transmission rate different than the first transmission rate of the first message,

the second satellite positioning system message including at least one of location, time, DGPS, ephemeris, almanac, ionispheric, and time offset information.