Telecommunications – Radiotelephone system – Including private cordless extension system
Patent
1997-12-17
2000-10-17
Hunter, Daniel S.
Telecommunications
Radiotelephone system
Including private cordless extension system
455410, 455465, H04M 1100
Patent
active
061344494
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a telecommunications system comprising at least a first unit and a second unit having each:
The invention also relates to a modification process of modifying identification codes of a first unit and of a second unit of a telecommunications system, said units including means for transmission by radio channel.
The invention also relates to a mobile unit intended to be used in a telecommunications system which includes a base unit with an identification code, said mobile unit having: unit,
The invention finally relates to a base unit intended to be used in a telecommunications system which includes at least one mobile unit with an identification code, said base unit having: mobile unit,
The invention notably has highly significant applications in the field of cordless telecommunications where it permits of improving the communication security between base unit and mobile unit.
BACKGROUND OF THE INVENTION
French Patent Application No. 2559008 filed by Sony, Jan. 31, 1985, describes a cordless telephone set comprising a base unit and a mobile unit having each an identification code: for a communication to be set up between the base unit and the mobile unit, their identification codes are to match. This patent application describes a mechanism for matching said identification codes by radio channel which requires that the mobile unit is put back on the base unit.
Such a solution has various drawbacks. On the one hand, it necessitates the use of physical detection means for detecting that the mobile unit rests on the base unit, which considerably increases the cost price of the telephone. On the other hand, it does not permit of changing the identification code at an arbitrary instant: the only criterions applicable are of the type "change of identification codes every n time intervals in which the mobile unit rests on the base unit". Finally, this process does not provide total reliability for the user, notably in the case where the user lifts the mobile unit before the base unit has received a clearing from the mobile unit.
SUMMARY OF THE INVENTION
The present invention notably has for its object to propose a telecommunications system which remedies these drawbacks.
Therefore, a telecommunications system according to the invention and as described in the opening paragraph is characterized in that: matched codes, operating only by radio channel, for substituting codes called new identification codes for codes called old identification codes, said units are correctly matched after such a modification before said old identification codes are deleted.
Thus, according to the invention, the previously matching identification codes of a base unit and a mobile unit may be modified by radio channel at an arbitrary instant, without the necessity of putting the mobile unit back on the base unit. The verification means make it possible to protect the system against radio disturbance or interruptions of power supply, by avoiding that the identification code is modified in only either of the two units, which would result in that the system would be put out of operation.
Moreover, as the identification codes of the mobile unit and base unit are to be matched beforehand, it is impossible to match a pirate mobile unit with the base unit by the mechanism of identification code modification according to the invention.
In an advantageous embodiment, said modification means are utilized on the initiative of said first unit at a request transmitted to said second unit by radio channel.
In another particularly advantageous embodiment, said verification means comprise: said first unit to permit said first unit to verify whether its new identification code has been correctly received by said second unit, said second unit to permit said second unit to verify whether said first acknowledgement has been correctly received by said first unit.
In a preferred embodiment: carry the identification code contained in its first storage means, carry the identification code contained in
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Halajian Dicran
Hunter Daniel S.
Nguyen Thuan T.
U.S. Philips Corporation
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