Method to protect against interference from mobile radios

• US 6,343,213 B1
• Filed: 10/24/1997
• Issued: 01/29/2002
• Est. Priority Date: 10/24/1997
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Steer, David, Teo, Koon Hoo
• Primary Examiner(s): Chang, Vivian
• Assistant Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US08/957,025
• Time in Patent Office: 1,558 Days
• Field of Search: 455/522, 455/456, 455/457, 455/419, 455/421, 455/411, 455/449, 174/35.MS, 174/35.R, 109/49.5
• US Class Current: 455/411
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 48/04 based on user or terminal location or mobility data, e.g. moving direction, speed
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A problem with mobile radio systems is the potentially harmful interference they may cause to other electronic equipment. Such interference can be dangerous and even life-threatening in hospitals and aircraft. Interference to automobile electronic braking systems, air bag actuators, or train system controls are examples of other areas where radio system interference must be prevented to preserve the safety of operators and passengers. The present invention provides a system whereby mobile radios, e.g. cellular phones, can be operated safely in regions where interference could cause serious problems or can be prevented from operating. The mobile radios are provided with a low power mode of operation and are commanded, via their signalling channels, to operate in the low power mode when within range of a low power signal from a base station within a protected area. In some areas where it may be undesirable for the mobile radio to operate, even at low power levels, the base station may broadcast an inhibiting signal which will instruct the mobile radio not to operate its transmitter while in the area.

Claims

1. A radio communication system comprising a plurality of base stations having respective coverage areas and a plurality of mobile stations and at least one protection base station having a coverage area which falls at least partly within the coverage area of at least one of the plurality of base stations, the coverage area of the protection base station defining a command zone surrounding a fully protected zone which cannot receive any control signals and which encompasses equipment that is susceptible to interference by transmission from the mobile stations, a portion of the coverage area of the at least one of the plurality of base stations lying outside the command zone defining a clear zone, wherein the protection base station has means to transmit command signals to command the mobile stations not to transmit and wherein the mobile stations have means responsive to the command signals and to signals from the base station within whose coverage area the coverage area of the protection base station falls to cause mobile stations moving from the clear zone through the command zone into the fully protected zone to disable their transmitters and to cause mobile stations moving out of the fully protected zone through the command zone into the clear zone to enable their transmitters.

2. A mobile station for use in a radio communication system comprising a first base station defining a coverage area, a protection base station having a coverage area falling within the coverage area of the first base station, the coverage area of the protection base station defining a command zone surrounding a fully protected zone and a portion of the coverage area of the first base station lying outside the command zone defining a clear zone, the mobile station comprising a transmitter, a receiver, means connected between the receiver and the transmitter, responsive to signals from the first base station and to command signals transmitted by the protection base station and present only in the command zone surrounding the fully protected zone, the means responsive causing the mobile radio as it moves from the clear zone through the command zone into the fully protected zone to disable its transmitter and causing the mobile radio when it moves out of the fully protected zone through the command zone into the clear zone to enable its transmitter.