Method for locating variable control channels by a mobile station in a radiotelephone system

• US 5,809,421 A
• Filed: 01/02/1996
• Issued: 09/15/1998
• Est. Priority Date: 01/02/1996
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Manssen, Keith R., Krolopp, Robert K.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/587,601
• Time in Patent Office: 987 Days
• Field of Search: 455/432, 455/433, 455/434, 455/435, 455/411, 455/515, 455/524
• US Class Current: 455/434
• CPC Class Codes: H04W 48/12 using downlink control channel

Abstract

A method for locating variable control channels by a mobile station (104) in a radiotelephone system (100) permits the mobile station (104) to quickly find the location of unknown control channels. A locator beacon (300) is transmitted on one or more common locator channels from each base station (102) or from a locator transmitter which covers the entire region. The locator beacon (300) includes control channel location information which defines the location in the spectrum of a designated control channel. A mobile station (104), including a roaming mobile station outside its home service area, tunes to the locator channel and detects the locator beacon (300) to read the control channel location information. In response, the mobile station (104) tunes to the frequency of the designated control channel to receive a control signal from the base station (102). To prevent co-channel interference, the base stations of a radiotelephone system (100) time division duplex the broadcast of respective locator beacons.

Claims

1. A method for initiating communication between a mobile station and a base station in a radiotelephone system, the radiotelephone system including a plurality of base stations, each base station configured for radio communication with a plurality of mobile stations including the mobile station within a fixed geographic area, the method comprising the steps of:

transmitting a locator beacon from each base station during a predefined unique time slot assigned to the base station, the locator beacon containing control channel definition information, transmitting the locator beacon including;

repeating transmission of a locator a predetermined number of times during the predefined time slot, and

initially transmitting a first predetermined data pattern before repeating transmission of the locator;

transmitting one or more control channels from each base station, the one or more control channels each including a control signal;

receiving the locator beacon during the predefined time slot at the mobile station of the plurality of mobile stations;

reading at the mobile station the control channel definition information from the locator beacon;

in response to the control channel definition information, selecting one control channel as a selected control channel at the mobile station;

detecting a selected control signal on the selected control channel at the mobile station; and

entering standby mode to await initiation of communication between the mobile station and one of the plurality of base stations.

2. A method for initiating communication between a mobile station and a base station in a radiotelephone system as recited in claim 1 wherein the step of repeating transmission of the locator includes transmitting the locator separated by a second predetermined data pattern.