Dual system cellular cordless radiotelephone apparatus with sub-data channel timing monitor

• US 5,442,680 A
• Filed: 08/25/1994
• Issued: 08/15/1995
• Est. Priority Date: 06/23/1992
• Status: Expired due to Term

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Schellinger, Michael J., Littig, Stefan G.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Bost, Dwayne D.
• Application Number:
  US08/296,263
• Time in Patent Office: 355 Days
• Field of Search: 379/58-61, 379/63, 450/33.1, 450/33.4, 450/34.1, 450/34.2, 450/54.1
• US Class Current: 455/426.1
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A cellular cordless telephone may receive cellular telephone calls via a cellular telephone system and receive telephone calls on a system having a limited radio coverage area. To reduce the amount of time spent in monitoring the sub-data channel of the limited coverage area system, a timing signal is generated which represents the period of time spent monitoring the radio channel. During the monitoring, a predetermined number of data words transmitted on the limited radio coverage area radio channel system are received. When a first received data word is detected, an allowed monitoring time value is adjusted to be the sum of the value of the timing signal and the product of a determined number of received words to be detected and the time required for each word. This adjusted value of the monitoring time value is compared to the value of the timing signal and when the adjusted monitoring time value equals or exceeds the timing signal value, the monitoring of the radio channel ceases.

Claims

1. A radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide radio coverage area, the radiotelephone apparatus interrupting its monitoring of messages from the second radiotelephone system in order to monitor the first radiotelephone system for messages the radiotelephone apparatus comprising:

means for establishing a monitoring time value;

means for monitoring for a period of time a radio channel associated with the first radiotelephone system;

means for generating a timing signal whereby the period of time spent monitoring said radio channel is measured;

means for receiving during said monitoring a predetermined number of data words transmitted on said radio channel associated with said first radiotelephone system;

means for detecting a first received data word;

means for readjusting said monitoring time value to be the sum of the value of said generated timing signal and the product of a determined number of received words to be detected and a predetermined value of time for each word;

means for incrementing said timing signal by a predetermined value;

means for comparing the value of said readjusted monitoring time value to the value of said incremented generated timing signal; and

means for ceasing monitoring of said radio channel when said readjusted monitoring time value equals or exceeds said incremented generated timing signal value, and returning to the second radiotelephone system.

2. A radiotelephone apparatus in accordance with claim 1 further comprising means for calculating said determined number of words to be detected, said means for calculating including means for generating a difference value between said generated timing signal and said established monitoring time value and means for rounding said generated difference value to the integer value equal to or less than said generated difference value.

3. A radiotelephone apparatus in accordance with claim 1 further comprising:

means for determining that the last data word is being received;

means for determining that said last data word cannot be detected; and

means, responsive to said determination that said last word cannot be detected, for ceasing monitoring of said radio channel.

4. A method of channel monitoring time period reduction for a radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide range coverage area, the radiotelephone apparatus interrupting its monitoring of the method comprising the steps of:

establishing a monitoring time value;

monitoring for a period of time a radio channel associated with the first radiotelephone system;

generating a timing signal whereby the period of time spent monitoring said radio channel is measured;

receiving, during said monitoring, a predetermined number of data words transmitted on said radio channel associated with said first radiotelephone system;

detecting a first received data word;

readjusting said monitoring time value to be the sum of the value of said generated timing signal and the product of a determined number of received words to be detected and a predetermined value of time for each word;

incrementing said timing signal by a predetermined value;

comparing the value of said readjusted monitoring time value to the value of said incremented generated timing signal; and

ceasing monitoring of said radio channel when said readjusted monitoring time value equals or exceeds said incremented generated timing signal value, and returning to the second radiotelephone system.

5. A method in accordance with the method of claim 4 further comprising the step of calculating said determined number of words to be detected by generating a difference value between said generated timing signal and said established monitoring time value and by rounding said generated difference value to the integer value equal to or less than said generated difference value.

6. A method in accordance with the method of claim 4 comprising the steps of.

determining that the last data word is being received;

determining that said last data word cannot be detected; and

ceasing said monitoring of said radio channel in response to said determination that said last word cannot be detected.

7. A radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide radio coverage area, the radiotelephone apparatus interrupting its monitoring of messages from the second radiotelephone system in order to monitor the first radiotelephone system for messages the radiotelephone apparatus comprising:

means for monitoring for a predetermined monitoring time value a channel associated with the first radiotelephone system;

means for generating a timing signal;

means for receiving during said monitoring a predetermined number of data words transmitted on said channel associated with said first radiotelephone system;

means, responsive to said monitoring time value and said generated timing signal, for determining that a last data word is being received;

means for determining that said last data word cannot be detected; and

means, responsive to said determination that said last word cannot be detected, for ceasing monitoring of said radio channel, and returning to the second radiotelephone system.

8. A method of channel monitoring time period reduction for a radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide radio coverage area, the radiotelephone apparatus interrupting its monitoring of messages from the second radiotelephone system in order to monitor the first radiotelephone system for messages the method comprising the steps of:

monitoring for a predetermined monitoring time value a channel associated with the first radiotelephone system;

generating a timing signal;

receiving, during said monitoring, a predetermined number of data words transmitted on said channel associated with said first radiotelephone system;

determining, in response to said monitoring time value and said generated timing signal, that a last data word is being received;

determining that said last data word cannot be detected; and

ceasing monitoring of said radio channel in response to said determination that said last word cannot be detected, and returning to the second radiotelephone system.

9. A radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide radio coverage area, the radiotelephone apparatus interrupting its monitoring of messages from the second radiotelephone system in order to monitor the first radiotelephone system for messages the radiotelephone apparatus comprising:

means for monitoring for a predetermined monitor time a channel associated with the first radiotelephone system;

means for generating a timing signal;

means for receiving a data word from said channel associated with the first radiotelephone system;

means, responsive to said data word being received by said means for receiving, for readjusting said predetermined monitor time into a monitor time value related to said timing signal and a determined number of data words to be received from said channel associated with the first radiotelephone system;

means for incrementing said timing signal by a predetermined value to produce an incremental timing signal;

means for comparing said readjusted monitor time value to said incremented timing signal; and

means for ceasing monitoring of said channel associated with the first radiotelephone system when said monitor time value exceeds said incremented timing signal, and returning to the second radiotelephone system.

10. A radiotelephone apparatus in accordance with claim 9 further comprising means for calculating said determined number of words to be detected, said means for calculating including means for generating a difference value between said timing signal and said monitor time and means for rounding said generated difference value to the integer value equal to or less than said generated difference value.

11. A radiotelephone apparatus in accordance with claim 9 further comprising:

means for determining that a last data word is being received;

means for determining that said last data word cannot be detected; and

means, responsive to said determination that said last word cannot be detected, for ceasing monitoring of said channel associated with the first radiotelephone system.

12. A method of channel monitoring time period reduction for a radiotelephone apparatus which receives messages preferably on a first radiotelephone system having a limited radio coverage area and which alternatively receives messages on a second radiotelephone system having a wide radio coverage area, the method comprising the steps of:

monitoring, for a predetermined monitor time, a channel associated with the first radiotelephone system;

generating a timing signal;

receiving a data word from said channel associated with the first radiotelephone system;

readjusting said predetermined monitor time into a monitor time value related to said timing signal and a determined number of data words to be received from said channel associated with the first radiotelephone system;

incrementing said timing signal by a predetermined value to produce an incremented timing signal;

comparing said readjusted monitor time value to said incremented timing signal; and

ceasing monitoring of said channel associated with the first radiotelephone system when said monitor time value exceeds said incremented timing signal, and returning to the second radiotelephone system.

13. A method in accordance with the method of claim 12 further comprising the step of calculating said determined number of words to be detected by generating a difference value between said timing signal and said monitor time and by rounding said generated difference value to the integer value equal to or less than said generated difference value.

14. A method in accordance with the method of claim 12 comprising the steps of:

determining that a last data word is being received;

determining that said last data word cannot be detected; and

ceasing said monitoring of said channel in response to said determination that said last word cannot be detected.