Network acquisition mechanism for mobile RF data

• US 5,548,818 A
• Filed: 08/25/1992
• Issued: 08/20/1996
• Est. Priority Date: 08/25/1992
• Status: Expired due to Fees

• Current Assignee: Westinghouse Air Brake Co (Westinghouse Air Brake Technologies Corporation)
• Original Assignee: Rockwell International Corporation
• Inventors: Kloster, Bruce S., Wilson, M. Frank, Kovatch, Randall M., Sawyer, James G., Roepke, Daniel C., Kitson, Ralph L.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): TO, DORIS HA
• Application Number:
  US07/934,980
• Time in Patent Office: 1,456 Days
• Field of Search: 455/33.2, 455/33.4, 455/34.2, 455/33.1, 455/32.1, 455/53.1, 455/54.1, 455/54.2, 455/56.1, 455/67.1, 455/67.4, 455/68, 455/161.1, 455/161.3, 455/168.1, 379/58, 379/59
• US Class Current: 455/515
• CPC Class Codes: H04W 48/10 using broadcasted information
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A method and system for radio communications between mobile units and base stations geographically distributed through a substantial geographic area described. The system automatically finds and engages broadcast frequency for each geographic region. The engagement is confirmed at both the mobile unit and network so that both can begin data transmission and reception between each other as well as keep track of the status of one another. The system also verifies the correct base station has been engaged as well as automatically terminates communications once the mobile unit passes out of coverage for that base station.

Claims

1. A system for RF communication network acquisition for RF communication between one or more mobile units and a plurality of base stations of a network having a plurality of RF broadcast regions distributed over a geographic area comprising:

means for issuing an RF beacon of selected frequency,

beacon messages and data content from the base stations;

means at base stations for adjusting periodic rate of issuance of the RF beacon according to data traffic at the base stations;

means on the mobile units for scanning a list of frequencies;

means on the mobile units for discerning if an RF beacon at a frequency from the list has been received; and

means on the mobile units for discerning if a beacon is of sufficient quality to carry on RF communication with the network;

wherein the means for discerning if the beacon is of sufficient quality includes timing means for determining if a threshold level of a number of beacon messages is received over a given time period;

means for continuing scanning the list of frequencies if the timer means determines the threshold level of number of beacon messages was not received within the given time period.

2. A system for RF communication network acquisition for RF communication between one or more mobile units and a plurality of base stations of a network having a plurality of RF broadcast regions distributed over a geographic area comprising:

means for issuing an RF beacon of selected frequency,

beacon messages and data content from the base stations;

means at base'"'"'stations for adjusting periodic rate of issuance of the RF beacon according to data traffic at the base stations;

means on the mobile units for scanning a list of frequencies;

means on the mobile units for discerning if an RF beacon at a frequency from the list has been received; and

means on the mobile units for discerning if a beacon is of sufficient quality to carry on RF communication with the network;

a means on the mobile unit for discerning if the RF beacon is no longer of sufficient quality to carry on RF communication;

wherein the means for discerning if the RF beacon is no longer of sufficient reliability includes a timer means for determining if receipt of RF beacons has stopped within a certain time period;

means on the mobile unit for reinstating a network acquisition process, when the timer means determines that receipt of beacons has stopped.