Data communications synchronization using GPS receiver

• US 6,763,241 B2
• Filed: 04/16/2001
• Issued: 07/13/2004
• Est. Priority Date: 04/14/2000
• Status: Expired due to Fees

• Current Assignee: Varitek Industries, Inc.
• Original Assignee: Varitek Industries, Inc.
• Inventors: Gous, John Peter, Stevenson, Timothy J.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US09/835,893
• Publication Number:
  US 20020037732A1
• Time in Patent Office: 1,184 Days
• Field of Search: 455/502, 455/67.1, 455/231, 455/51.1, 455/457, 455/13.2, 455/13.3, 455/517, 342/357.01, 342/357.02, 342/357.03, 342/357.1, 342/357.12, 342/357.06
• US Class Current: 455/502
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 5/0063 of measured values, i.e. measurement on base station and position calculation on mobile
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver

Abstract

Disclosed is a system that uses GPS synchronization pulses in a communications system to provide synchronization of the transmission of data during assigned time slots. In addition, mobile units can calculate the distance from a base station based upon GPS coordinates that are provided by the GPS system. The distance of the mobile unit from the base station is then used to calculate the time required to transmit data from the mobile unit to the base station so that data from the mobile unit arrives at the base station during the assigned time slot for that particular mobile unit. Additionally, base station synchronization pulses are transmitted by the base station to the mobile units to empirically synchronize the internal bit clocks of the mobile units to insure proper sampling of data.

Claims

1. A method of synchronizing the transmission of information in assigned time slots between mobile transceiver units having GPS receivers and a base station having a GPS receiver comprising:

using said GPS receiver in said mobile units for receiving GPS synchronization data;

using said GPS receiver in said base station to receive said GPS synchronization data;

using a GPS synchronization pulse generated from said GPS synchronization data to synchronize internal bit clocks in said mobile units and said base station to provide GPS synchronized internal bit clocks in said mobile units and said base station;

transmitting base station synchronization pulses from said base station to said mobile units that are synchronized with said GPS synchronized internal bit clock of said base station;

further synchronizing said GPS synchronized internal bit clocks of said mobile units with said base station synchronization pulses to produce empirically synchronized internal bit clocks of said mobile units;

transmitting data from said mobile units in assigned time slots using said empirically synchronized internal bit clocks of said mobile units.

2. The method of claim 1 further comprising:

using GPS coordinate data of said mobile units and said base station to generate distance delay data that is representative of a time period required for transmitting data between said mobile unit and said base unit,

obtaining channel delay data for said mobile units;

generating forward transmission skew data for said mobile units from said distance delay data and said channel delay data.

3. The method of claim 2 further comprising:

generating a transmission time for each mobile unit from said forward transmission skew, assigned time slot information and said internal bit clocks of said mobile units that are synchronized to said GPS synchronization pulse.

4. The method of claim 2 wherein said step of obtaining channel delay data comprises:

retrieving said channel delay data from a storage device associated with said mobile unit.

5. The method of claim 2 wherein said step of obtaining channel delay data comprises:

obtaining said channel delay data from field tests of said mobile units.

6. A system for synchronizing the transmission of data in assigned time slots comprising:

mobile units that have communication transceivers;

a base station having a communication transceiver for communicating with said mobile units;

GPS receivers disposed in said mobile units and said base station that receive GPS synchronization data and generate GPS synchronization pulses and GPS coordinate information from said GPS synchronization data;

internal bit clocks disposed in said mobile units and said base station that are calibrated to said GPS synchronization pulses to produce GPS synchronized internal bit clocks;

logic control devices disposed in said mobile units that are programmed to control the transmission of data from said mobile units to said base station in assigned time slots and that are programmed to further synchronize said GPS synchronized internal bit clocks of said mobile units with base station synchronization pulses, said base station synchronization pulses being synchronized with said GPS synchronized internal bit clock of said base station.

7. The system of claim 6 whereas said logic control devices comprises:

microprocessors programmed to use said GPS coordinate data to generate distance delay data this is representative of a time period required to transmit data between said mobile units and said base unit, obtain channel delay data for said mobile units and generate forward transmission skew data from said distance delay data and said channel delay data.

8. The system of claim 7 wherein said microprocessors comprise:

microprocessors that are further programmed to generate a transmission time that indicates the time at which said mobile units can transmit data so that said data arrives at said base station in said assigned time slots using said forward transmission skew data, assigned time slot information for said mobile units and said GPS synchronized internal bit clocks.