Communication in a wireless communications network when a mobile computer terminal may be unreachable

• US 7,206,849 B1
• Filed: 10/10/2000
• Issued: 04/17/2007
• Est. Priority Date: 10/05/1998
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Gernert, Alex M., Scheve, Daniel L.
• Primary Examiner(s): Wiley; David
• Assistant Examiner(s): NEURAUTER, GEORGE C
• Application Number:
  US09/686,123
• Time in Patent Office: 2,380 Days
• Field of Search: 709/200, 709/229, 370/349, 455/421, 455/466, 713300-340
• US Class Current: 709/229
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode

Abstract

A method and apparatus for communication between a mobile computer terminal and a host computer in a system in which it is necessary for the mobile computer terminal to send a message to the host computer at a particular time. The specific time at which the mobile computer terminal must send a message to the host computer is first determined. Then, a timer or clock is programmed to wake up the mobile computer terminal at the specific time. A sleep mode may be entered, which may be interrupted at the specific time to send the message. This will normally allow a mobile computer terminal to maintain its lease on an IP address despite being out of range of a wireless network.

Claims

1. A method for preventing a mobile computer from being disconnected from a network comprising:

determining a termination time of a network connection for said mobile computer;

setting a timer for a time prior to said termination time responsive to said determination of said termination time;

setting said mobile computer into a sleep mode responsive to setting of said timer;

setting said mobile computer to an active mode responsive to said timer expiring;

transmitting a message from said mobile computer to a host computer in said network responsive to said mobile computer being set to said active mode wherein said message is a request for an extension of a lease of an Internet Protocol Address for said mobile computer;

determining whether said mobile computer is out of transmission range of said host computer;

displaying an out of range message on a display screen of said mobile computer responsive to a determination that said mobile computer is out of said transmission range;

setting a re-transmit timer responsive to a determination of said mobile computer being out of said transmission range; and

re-transmitting said message responsive to an expiration of said re-transmit timer.

2. The method of claim 1 wherein said message is a lease renewal message.

3. A mobile computer terminal comprising:

means for determining an expiration time for a network connection for said mobile computer terminal;

means for setting a wake-up timer that expires prior to said expiration time;

means for setting said mobile computer terminal to a sleep mode responsive to said wake-up timer being set;

means for setting said mobile computer terminal to an active mode responsive to said wake-up timer expiring;

means for transmitting a message to said network prior to said expiration time responsive to said mobile computer terminal being set to an active mode wherein said message includes a request to extend a lease of an Internet Protocol Address for said mobile computer terminal;

means for determining whether said mobile computer is out of transmission range of said host computer;

means for displaying an out of range message on a display screen of said mobile computer responsive to a determination that said mobile computer is out of said transmission range;

means for setting a re-transmit timer responsive to a determination of said mobile computer being out of said transmission range; and

means for re-transmitting said message responsive to an expiration of said re-transmit timer.

4. The mobile computer terminal of claim 3 wherein said message is a lease renewal message.

5. A mobile computer terminal comprising:

a transceiver unit for transmitting and receiving messages;

a hand-held image scanner;

a processing unit;

instructions for directing said processing unit to;

read an image from said hand-held image scanner,

transform data corresponding to said image,

generate a data message including said data, said data message having a format and ordering expected by a host computer system,

transmit said data message to said host computer system,

determine an expiration time for a connection time between said mobile computer terminal and said host computer system,

set a timer to expire prior to said expiration time,

set said mobile computer terminal to a sleep mode responsive to setting said timer,

set said mobile computer terminal to an active mode responsive to an expiration of said timer,

transmit a connection message to said host computer system prior to said expiration time responsive to said mobile computer terminal being set to an active state wherein said connection message requests an extension of a lease of an Internet Protocol Address for said mobile computer terminal,

determine whether said mobile computer terminal is out of transmission range of said host computer,

display an out of range message on a display screen of said mobile computer terminal responsive to a determination that said mobile computer is out of said transmission range,

set a re-transmit timer responsive to a determination of said mobile computer terminal being out of said transmission range, and

re-transmit said message responsive to an expiration of said re-transmit timer; and

a media readable by said processing unit that stores said instructions.

6. The mobile computer terminal of claim 5 wherein said connection message is a lease renewal message.

7. A method for transmitting data between a mobile computer terminal and a host computer system wherein said mobile computer terminal includes a transceiver unit for transmitting and receiving messages, said method comprising:

reading an image from said hand-held image scanner;

transforming data corresponding to said image;

generating a data message including said data, said data message having a format and ordering expected by a host computer system;

transmitting said data message to said host computer system;

determining an expiration time for a connection time between said mobile computer terminal and said host computer system;

setting a timer in said mobile computer terminal to expire prior to said expiration time;

setting said mobile computer terminal to a sleep mode responsive to setting said timer;

setting said mobile computer terminal to an active mode responsive to an expiration of said timer;

transmitting a connection message from said mobile computer terminal to said host computer system prior to said expiration time responsive to said mobile computer terminal being set to an active state wherein said connection message requests an extension of a lease of an Internet Protocol Address for said mobile computer terminal;

determining whether said mobile computer terminal is out of transmission range of said host computer;

displaying an out of range message on a display screen of said mobile computer terminal responsive to a determination that said mobile computer is out of said transmission range;

setting a re-transmit timer responsive to a determination of said mobile computer terminal being out of said transmission range; and

re-transmitting said message responsive to an expiration of said re-transmit timer.

8. The method of claim 7 wherein said connection message is a lease renewal message.