Communications system for integrating a paging system with cellular radio telephones

• US 5,541,976 A
• Filed: 06/07/1995
• Issued: 07/30/1996
• Est. Priority Date: 04/17/1991
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Ghisler, Walter
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): OEHLING, GEORGE J
• Application Number:
  US08/476,041
• Time in Patent Office: 419 Days
• Field of Search: 379/57, 379/58, 379/59, 455/38.3, 455/127, 455/343, 455/33.1
• US Class Current: 455/426.1
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The present invention relates to a cellular mobile radio telephone system which incorporates an independent paging capability with an existing mobile telephone by taking advantage of call forwarding and redirecting features available on the telephone switching network. When a mobile telephone is set to an active or "on" mode, calls are directed to that mobile telephone using the cellular paging channel and conventional cellular paging procedures. However, when the mobile telephone is set to a sleep mode and the power is switched off, the mobile switching center automatically forwards calls to the mobile to an independent paging system which transmits the call as a paging signal to a small pager associated with the mobile telephone. When the pager receives a page signal as a result of the forwarded call, the pager transmits a low-power signal to the mobile telephone which switches on the power of the mobile telephone. A predetermined time after forwarding the call to the paging system, the mobile switching center redirects the forwarded calls using redirecting procedures to the mobile telephone. By the time the call is redirected, the mobile station has been activated and can now receive the call directly. Because the active pager consumes much less power than the mobile telephone listening to a paging channel of the cellular system, setting the mobile telephone to the sleep mode results in considerably less battery drain. When the mobile is set to a page mode, the pager functions as a conventional paging device.

Claims

1. A cellular communication system, where mobile telephones communicate with a network switching center via a corresponding base station, and used in conjunction with a paging system, comprising:

a plurality of mobile radio telephones, each mobile telephone operating in one of multiple modes; and

a plurality of pagers, each pager transmitting and receiving only radio signals and being associated with but separate from one of said plurality of mobile telephones, wherein each of said pagers comprises;

a receiver for receiving page signals and an identification number specific for the pager;

control means connected to said receiver for generating an activation signal when said mobile telephone is in a first mode; and

a transmitter connected to said control means for generating a radio signal having a frequency different from the radio frequencies sent between said base station and the mobile station, modulated by a low frequency signal which is specific for the pager, wherein the radio signal includes an address of the mobile telephone associated with the pager, wherein each of said mobile telephones has a receiver including demodulating means for demodulating, in correspondence with the modulation of said radio signal transmitted from the pager, said radio signal from said transmitter in the associated pager for generating an activating signal in order to provide power to the mobile telephone;

wherein said paging system comprises;

means for monitoring a total number of page requests;

means for comparing said total number of page requests with a predetermined limit; and

means for ordering at least one mobile telephone to switch from said first mode to a second mode when said total number of page requests exceeds said predetermined limit.

2. The system according to claim 1, wherein said first mode is a sleep mode.

3. The system according to claim 1, wherein said ordered mobile telephone monitors cellular paging signals transmitted on a control channel associated with said corresponding base station.