Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-06-11
2001-09-11
Maung, Nay (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S517000, C455S414200, C370S503000
Reexamination Certificate
active
06289218
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for direct communication, and more particularly to a method for communicating handsets.
BACKGROUND OF THE INVENTION
The DECT (Digital Enhanced Cordless Telecommunications) is the protocol for European digital wireless telephone and can be applied for residential PABX (Private Automatic Branch Exchange). So far there is no design for direct communication of two handsets in Europe, which means that two handsets must communicate with each other through the base and be located in a place where the radio signal from the base can be received.
Referring to
FIG. 1
, there is schematically shown the present condition. The Base
1
is necessary for the communication of the Handset#
1
2
and the Handset#
2
4
which both communicate with the external (by the PSTN/ISDN) through the exchange
3
of the telephone company. The curve BSR is the boundary of the service range of Base
1
. We can see that the Handset#
12
5
is out of the service range and cannot communicate with Handset·
2
4
though their distance is very short. The multiple handsets (parties, branches or extensions) DECT wireless telephone would be more attractive if it possesses a function similar to walkie-talkie as handsets are located far away from where the base is placed.
Referring now to
FIG. 2
, the DECT wireless communication standard belongs to a TDMA (Time Division Multiple Access) system and is planned to occupy 10 channels (carriers) each of which is called a DECT frame divided into 24 time slots and programmed into 12 Full Duplex Bearers wherein 12 time slots are used for up link communication and another 12 time slots for down link communication. In such DECT system, handsets communicate with each other through base
1
, cannot communicate with the external if located outside of the service range of base
1
, and cannot communicate with each other directly.
According to the Japanese PHS (Personal Handyphone System) which selects 10 channels out of all available channels for communicating PHS handsets, however, handsets are directly communicable in the following manner. In direct communication mode continuously scanning the 10 channels, when a (calling) handset is to call, an empty channel is selected to emit the control signal to call another (called) handset which will, once receiving the calling signal, answer the calling handset to connect and directly communicate with each other.
Since the 10 channels are to be continuously scanned and the signals are to be continuously emitted which thus are relatively energy-consuming, in order to be energy-saving, some one suggests calling and called handsets can communicate with each other if they transmit and receive signals both in the same one of the time slots of the same one of the 10 channels through the synchronous characteristics of the handset and the base. Such system still suffers from the disadvantage that handsets must be located within a region capable of receiving the radio signal of the same base in order to be able to be sychronous.
It is therefore tried by the applicant to overcome the above problems encountered by the prior art.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method of directly communicating handsets without the involvement of the base. It is another object of the present invention to provide a method of communicating handsets which are to transmit phonetic signals only when the user is talking.
It is further an object of the present invention to provide a method of communicating handsets which are relatively energy-saving. According to the present invention, a method for directly communicating handsets includes the following steps of providing a calling handset and a called handset, inputting a first number to the calling handset for obtaining a first identification (ID) code therefor, inputting a second number to the called handset for obtaining a second ID code therefor, transmitting the first ID code from the calling handset to the called handset when the calling handset is to call the called handset, receiving the first ID code by the called handset, identifying whether the first ID code matches with the second ID code, and synchronizing the two handsets for a direct communication if the first and second ID codes match with each other.
Certainly such handsets can be used in a European DECT system. The first and second numbers can be respectively encoded by the calling and called handsets into the first and second ID codes respectively. The identifying step can identify whether the first and second ID codes are identical at least in part, or alternatively are matchable with each other somehow. Preferably each of the first and second ID codes includes a direct communication ID code and a channel number.
Preferably when the calling handset calls the called handset in the present method, the calling handset enters into a direct communication idle mode in which the calling handset will proceed a direct communication calling mode for calling the called handset when a direct communication initialization of the calling handset is true.
Preferably in the direct communication calling mode, there are the following steps of locating an unused one of time slots of a respective channel, defining the one time slot as a predetermined time slot of the calling handset, and transmitting the direct communication ID code of the calling handset to the called handset in the predetermined time slot, and entering into a direct communication connection mode upon receiving an answering signal from the called handset.
Preferably a code representing the predetermined time slot is generated when the first number is encoded into the first ID code in order to synchronize handsets.
Preferably the direct communication connection mode includes the following steps of returning to the direct communication idle mode when a handshake acknowledge signal from the called handset fails, and connecting a phonetic signal of the calling handset for proceeding a directly communicating procedure upon receiving a start communication signal from the called handset.
Preferably the directly communicating procedure includes the following steps of transmitting a handshake acknowledge signal for connecting the handsets in an A-field of the predetermined time slot, and transmitting the phonetic signal to the called handset in a B-field of the predetermined time slot when a user of the calling handset is talking.
Preferably when the called handset receives the first ID code, the called handset enters into a direct communication idle mode which includes the following steps of entering into an idle state, scanning time slots of a channel corresponding the channel number, and finding a specific time slot in which a calling signal from the calling handset is received, and entering into a direct communication receiving mode when the direct communication ID codes of the first and second ID codes match with each other during the specific time slot.
Preferably the direct communication receiving mode includes the following steps of defining the specific time slot as a predetermined time slot of the called handset, transmitting an answering signal to the calling handset, and entering into a direct communication connection mode. A a code representing the predetermined time slot is generated when the second number is encoded into the second ID code in order to synchronize the handsets.
Preferably the direct communication connection mode includes the following steps of returning to the direct communication idle mode when a handshake acknowledge signal from the calling handset fails, transmitting a starting communication signal to the calling handset once a user of the called handset decides to connect, and connecting a phonetic signal of the called handset for entering into a directly communicating mode.
Preferably the directly communicating mode includes the following steps of transmitting a handshake signal for maintaining a connection between the handsets in an A-field of the pre
Craver Charles
Knobbe Martens Olson & Bear LLP
Maung Nay
Winbond Electronics Corporation
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