Method and apparatus of preserving power of a remote unit in a dispatch system

• US 5,884,196 A
• Filed: 06/06/1996
• Issued: 03/16/1999
• Est. Priority Date: 06/06/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Grob, Matthew S., Yao, Yu-Dong, Lekven, Eric J.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US08/660,619
• Time in Patent Office: 1,013 Days
• Field of Search: 455/574, 455/343, 455/38.3, 455/127, 370/311, 370/342
• US Class Current: 455/574
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 52/0238 where the received signal is an unwanted signal, e.g. interference or idle signal
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

To reduce the power consumption of a remote unit in a dispatch system the remote unit enters a dormant state. A base station transmits a forward link broadcast signal and monitors a common access channel. A first remote unit continually receives and decodes the forward link broadcast signal and determines whether said forward link broadcast signal comprises active signals. If the remote unit determines that the forward link broadcast signal comprises no active signals for some a duration T₁, the first remote unit enters a dormant mode. In the dormant mode the remote unit sporadically receives and decodes said forward link broadcast signal. If this remote unit or any other remote unit on the same net presses a push to talk button, it transmits a message on the common access channel. In response, every remote unit on the net which is in a dormant state exits the dormant state and continually monitors the forward link broadcast signal.

Claims

1. A method for reducing the power consumption of a remote unit in a dispatch system comprising the steps of:

transmitting from a base station a forward link broadcast signal;

receiving and decoding continually said forward link broadcast signal at a first remote unit and determining whether said forward link broadcast signal comprises active signals;

entering a first dormant state by said remote unit if said remote unit determines that said forward link broadcast signal comprises no active signals for a duration T₁ wherein said remote unit receives and decodes sporadically said forward link broadcast signal at said first remote unit; and

reducing a power consumption of said remote unit in said first dormant state.

2. A method of conserving power in a remote unit of a dispatch system comprising the steps of:

entering a listen state, by a first remote unit, wherein said first remote unit continuously monitors a forward link broadcast channel and transmits requests for increased broadcast power if necessary;

entering a first dormant state, by said first remote unit, if an activity level on said forward link broadcast channel falls below a predetermined activity level, wherein in said first dormant state said first remote unit monitors said forward link broadcast channel only during a first predetermined set of time slots spaced apart in time and transmits requests for increased broadcast power if necessary; and

reducing an amount of power consumed by said first remote unit in said first dormant state.

3. The method of claim 2 further comprising the step of exiting said first dormant state and entering a second dormant state wherein said first remote unit monitors said forward link broadcast channel only during a second predetermined set of time slots more greatly spaced apart in time than said first predetermined set of time slots and transmits requests for increased broadcast power if necessary.

4. The method of claim 3 wherein said first remote unit enters said second dormant state in response to a command on said forward link broadcast channel.

5. The method of claim 2 further comprising the step of exiting said first dormant state and re-entering said listen state if a broadcast alert is transmitted on said forward link broadcast channel.

6. The method of claim 5, wherein a base station generates said broadcast alert in response to receipt of a push-to-talk access message from a second remote unit.

7. The method of claim 2 further comprising the step of exiting said first dormant state and entering an access state in response to a push-to-talk indication generated by said first remote unit.

8. The method of claim 7 further comprising the step of re-entering said listen state from said access state in response to a release of said push-to-talk indication.

9. The method of claim 7 further comprising the step of transmitting a broadcast alert on said forward link broadcast channel in response to said push-to-talk indication, so as to cause a second remote unit to exit a second unit dormant state and enter a second unit listen state.

10. The method of claim 2 wherein said first remote unit enters said first dormant state autonomously.

11. The method of claim 2 wherein said first remote unit enters said first dormant state in response to a command on said forward link broadcast channel.

12. The method of claim 2 further comprising the step of dialing a net number and initializing communication by transmitting signals to a base station.

13. The method of claim 12 further comprising the step of entering an idle state if a broadcast net is not established and wherein said step of entering said listen state is performed in response to a page from said base station indicating that said broadcast net has been established.

14. The method of claim 12 wherein said forward link broadcast channel uses code division multiple access signaling.

15. The method of claim 2 wherein said first remote unit may be used as a point-to-point telephone as well as a push-to-talk dispatch unit.

16. The method of claim 12 wherein said base station functions as a point-to-point base station as well as a dispatch base station.

17. A system for conserving remote unit power in a dispatch system comprising:

a plurality of remote units, each configured to receive a forward link broadcast channel continuously in a listen state and to monitor link activity on said forward link broadcast channel, wherein each of said plurality of remote units enters a first dormant state if said link activity falls below a predetermined threshold; and

a base station configured to generate a broadcast alert on said forward link broadcast channel in response to a push-to-talk indication received from one of said plurality of remote units on an access channel, wherein said broadcast alert commands said plurality of remote units to exit said first dormant state.

18. An apparatus for controlling a remote unit operating in a dispatch system comprising:

means for continuously receiving a forward link broadcast channel;

means for determining a level of activity on said forward link broadcast channel; and

means for receiving said forward link broadcast channel during a first predetermined set of time slots, spaced apart in time, if said level of activity on said forward link broadcast channel falls below a predetermined activity level.

19. The apparatus of claim 18 further comprising means for reducing an amount of power consumed by said remote unit when said remote unit is receiving said forward link broadcast channel during said first predetermined set of time slots.

20. The apparatus for control of a remote unit of claim 19 further comprising means for receiving said forward link broadcast channel during a second predetermined set of time slots which are more greatly spaced apart in time than said first predetermined set of time slots, and only if said activity level on said forward link broadcast channel falls below a second predetermined activity level.