Telecommunications – Radiotelephone system – Out-of-range indication
Reexamination Certificate
1999-03-24
2001-12-11
Legree, Tracy (Department: 2681)
Telecommunications
Radiotelephone system
Out-of-range indication
C455S462000, C455S422100
Reexamination Certificate
active
06330437
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a range limit verification method in a wireless telecommunications system including at least two parts that may communicate by radio channel inside a coverage area, the method including a reading step of reading an electric field level received by the second part and transmitted by the first part for detecting a range-limit electric signal.
The invention likewise relates to wireless telecommunications equipment including at least a first and a second part that can communicate by radio channel inside a coverage area, said equipment including detection means for detecting an electric field level received by the second part and transmitted by the first part for detecting a range-limit signal.
The invention finally relates to a base station and a handset suitable for such equipment.
The invention is notably applied to wireless telephones in accordance with a CT0 standard.
BACKGROUND OF THE INVENTION
The publication of the ICC Conference 1983, vol. 1, pp. 64-67, of which the conference entitled “Integrating Communication for World Progress” was held at Boston, Mass. from to Jun. 19 to 22, 1983, describes a method of predicting the radio range of telecommunications equipment based on the measurement of an indicator of electric field strength received locally while environment factors such as height and building density are taken into account. This method utilizes databases, which enable to determine the topography of the terrain between a base station and a mobile handset.
SUMMARY OF THE INVENTION
It is an object of the invention to provide simple means for avoiding that a radio communication between two parts of telecommunications equipment is cut off because of environmental conditions that disturb the local electric field received by one of the parts.
Therefore, a method as defined in the opening paragraph is provided, characterized in that the detection of said range-limit signal triggers a presence verification step of verifying the presence of said first part inside the coverage area, including a transmission of a radio message requesting a confirmation of presence to said first part.
According to an important characteristic feature of the method, said presence verification step includes:
a repetition step of:
sending said radio message requesting a confirmation of presence to said first part and
receiving a presence-confirmation message,
this step being repeated as long as the confirmation message is received by said second part in a given period of time, and
a step of cutting off radio communications between said parts, triggered if said confirmation is not received in said period of time.
According to another important characteristic feature of the method, said repetition step is stopped when, during said reading step, a received electric field level is detected that exceeds a predetermined detection threshold.
Similarly, the invention provides equipment as defined in the opening paragraph, characterized in that it includes presence verification means for verifying the presence of the first part inside area, these means being triggered by the detection of said range-limit signal.
According to an important characteristic feature of the invention, said presence verification means are deactivated by the detection of a received electric field level that is higher than a predetermined threshold.
According to another characteristic feature of the invention, the presence verification means include:
transmitting means for sending a message requesting a confirmation of presence to said first part at given time intervals,
delay means for triggering a delay that corresponds to said time intervals,
receiving means for receiving said presence confirmation message,
means for cutting off radio communications, triggered if said presence confirmation message is not received by said second part in a given period of time.
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Bordeau Jean-Pascal
Bozzetto Olivier
Gelin Jean A
Halajian Dicran
Legree Tracy
U.S. Philips Corporation
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