Dialing method in wireless local loop terminal

Details Dialing method in wireless local loop terminal Dialing method in wireless local loop terminal

1999-08-02

2001-07-03

Urban, Edward F. (Department: 2683)

Telecommunications

Having single-channel telephone carrier

Including call signaling

C455S564000, C455S565000, C379S360000

Reexamination Certificate

active

06256488

ABSTRACT:

PRIORITY
This application claims priority to an application entitled “Dialing Method in Wireless Local Loop Terminal” filed in the Korean Industrial Property Office on Aug. 1, 1998 and assigned Ser. No. 98-31446, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for enabling a wireless local loop (WLL) terminal to process dial signals received from a wire telephone, and more particularly, to a dialing method for recognizing the end of a dialing sequence by detecting a specific key input.
2. Description of the Related Art
A wired telephone, as well as a wireless local loop (WLL) telephone, are connected to a WLL terminal via a tip terminal T and a ring terminal R.
FIG. 1
shows a configuration of a WLL terminal to which a wire telephone (e.g., a public telephone) is connected. The wired telephone requires, in addition to the tip terminal T and the ring terminal R, a subscriber line interface circuit (SLIC) as shown in FIG.
1
.
In operation, when a wire telephone
100
is in an off-hook state, the loop current varies. A signal line indicating circuit (SLIC)
25
in a WLL terminal
200
detects the off-hook state of the telephone
100
as a consequence of the change in the loop current. In the off-hook state, if a subscriber dials a telephone number, a dual tone multifrequency (DTMF) signal corresponding to each dialed key is sent to the SLIC
25
via the tip terminal T and ring terminal R connections as shown in FIG.
1
. The DTMF signal is supplied from the SLIC
25
to a DTMF receiver
26
where it is converted into a digital signal. A controller
27
temporarily stores the digital signal received from the DTMF receiver
26
in an internal dial buffer
27
a.
Upon detecting completion of dialing, the controller
27
reads the stored digital signal and supplies the read digital signal to a DTMF generator
27
b
where a DTMF signal is generated from the received digital signal to be supplied to a radio transmitter/receiver (hereinafter, referred to as an RF (Radio Frequency) circuit
28
. The RF circuit
28
modulates the received DTMF signal and wirelessly transmits the modulated signal.
To detect the end of the dialing sequence, a timer is required. After recognizing a single key input, the controller
27
activates the timer and checks whether the next key is input within a prescribed time (e.g., 5 seconds). If there is no key input received within the time interval, it is judged that dialing has been completed.
In the case where the timer is used, a long timer check time may increase a long loop linking time; however, a short timer check time may cause mis-recognition in detecting end of dialing when there is a pause in dialing.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for accurately and rapidly processing dial signals received from a wire telephone in a WLL terminal.
It is another object of the present invention to provide a method for increasing accuracy and loop linking speed in processing dialed signals in a WLL telephone.
In accordance with one aspect of the present invention, a method for processing dialed signals from a telephone connected to a WLL terminal by wires includes the steps of: sensing whether the telephone is in an off-hook state; if the telephone is in an off-hook state, receiving a DTMF signal corresponding to a key input from the telephone; converting the DTMF signal into a digital signal; checking whether the digital signal is a predefined specific key, and if the digital signal is not a predefined specific key, storing the digital signal in a dial buffer and returning to the receiving step; and if the digital signal is a predefined specific key, sequentially generating the DTMF signal corresponding to the digital signal stored in the dial buffer to radio-transmit the DTMF signal.
In accordance with another aspect of the present invention, a method for processing dialed signals from a WLL telephone includes the steps of: sensing whether a handset is in an off-hook state; if the handset is in an off-hook state, generating a DTMF signal corresponding to a key input from a keypad; converting the DTMF signal into a digital signal; checking whether the digital signal is a predefined specific key, and if the digital signal is not a predefined specific key, storing the digital signal in a dial buffer and returning to the receiving step; and if the digital signal is a predefined specific key, sequentially generating the DTMF signal corresponding to the digital signal stored in the dial buffer to radio-transmit the DTMF signal.


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