KR100349651B1 - Method for modem communication in Wireless Local Loop system - Google Patents

Abstract

The present invention is a modem in a wireless subscriber network system which enables wireless communication with many data terminals requiring low speed data communication by implementing a modem communication using a tip-ring in a wireless subscriber network terminal. The present invention relates to a communication method, by using a V.22bis communication method, which is a modem protocol through tip-ring when pay-phone is connected to a wireless subscriber network (WLL) terminal. The communication between the terminal and the public telephone is made so that asynchronous data can be exchanged between the wireless subscriber network terminal and the public telephone, and the state of the public telephone connected to the wireless subscriber network terminal can be monitored and managed.

Description

Modem communication method in wireless subscriber network system {Method for modem communication in Wireless Local Loop system}

The present invention relates to a wireless local loop (WLL) system, and more particularly, requires low-speed data communication by implementing a modem communication using a tip-ring in a wireless subscriber network terminal. The present invention relates to a modem communication method in a wireless subscriber network system that enables wireless communication with many data terminals.

In general, wireless local loop (WLL) is a technology that provides a subscriber line wirelessly, unlike a conventional wired subscriber network connecting a switch and an individual general subscriber through a wired subscriber line. After the development of RF technology and the development of semiconductor and wireless communication technology in the late 1980s, the previous problems such as frequency efficiency, wireless channel quality, and cost per subscriber were solved. In addition, WLL is easier to construct subscriber lines than existing wired subscriber networks, and can be used as an emergency subscriber line in preparation for natural disasters, and can provide various services such as POTS, data, and ISDN.

Due to the above advantages, WLL attracts new subscribers early and establishes new subscribers quickly in urban areas. In particular, WLL is gaining attention as a communication infrastructure of developing countries where wired network structure is poor. Products developed for WLL include satellite system, fixed microwave system, cellular technology system and cordless system system. have.

The system employing this cellular technology has three multiple access methods, namely, Frequency Division Multiplexing Access (FDMA), Time Division Multiplexing Access (CDMA) and Code Division Multiple Access (CDMA). Dvision Mutiplex Access) is used. Commercially available products include FDMA and TDMA, but they are shifting to CDMA, which has a much larger subscriber capacity than other access methods. WLL has similar characteristics to mobile communication network in terms of using wireless channel as a communication medium, but it has the advantage that radio wave environment of WLL network is much better than that of mobile communication network because there is no mobility. It has the same characteristics.

First, the propagation environment of the mobile communication network is located at the position where the antenna height is lower than the surrounding buildings, and as a result, it becomes a non-line-of-sight environment, which blocks the direct waves by the surrounding buildings, reflects, and diffracts. Although the radio wave path loss is about 40dB / decade, the radio wave environment of the WLL network can be installed in a high place such as the roof of a building, so the line-of-sight environment is secured, so the radio wave path loss is 20dB / decade. It is small enough to service a larger area with the same transmit power.

Second, since the radio wave environment of the WLL network is point-to-point fixed communication, fading due to multiple paths is much less than that of the point-to-mobile mobile communication network. Eb / No required for mobile radio wave environment using 30KHz channel bandwidth is 18dB, but Eb / No required for radio wave environment of WLL network using same channel bandwidth is only about 14dB required for low power transmitter Do.

Third, since the WLL network is a fixed wireless communication network, no handoff occurs. Therefore, it is not necessary to secure an extra handoff radio channel necessary for communication service without disconnection in the mobile communication network, and it is not necessary in the WLL network. This extra radio channel can be used for general calls, which increases the efficiency of the radio channel and the capacity of subscribers. The increase effect of can be obtained. In addition, the wireless link between each building and the base station can be established in a direction to reduce interference to a particular subscriber. Since the wireless link is unchanged unless the subscriber increases too much or the cell is divided after being installed, the wireless link of the WLL network cannot be changed. The design is much simpler than a mobile network.

Fourth, since the WLL network is a fixed wireless communication, it is possible to reduce the co-channel interference effect on individual subscribers by using a directional antenna for the forward / reverse link, thereby reducing the frequency reuse distance. Reduction of frequency reuse distance results in an increase in subscriber capacity per unit area.

The wireless subscriber network system may include a separate terminal located in a subscriber's home as a subscriber access device, a base station for converting a wireless signal received from the separate terminal into a wired signal, and a switch connecting a transmitting side to a receiving side. The detachable terminal of the wireless local loop system is connected to a general telephone, facsimile or personal computer which is an external device through a port.

The wireless subscriber network system can be classified into a narrowband wireless subscriber network system (Narrowband WLL) and a wideband wireless subscriber network system (Wideband WLL), both of which use CDMA. In particular, the narrowband wireless subscriber network system is only mobile in the system applied to the mobile communication technology since the mid 90's due to the rapid decrease of the system and the terminal due to the rapid development of the mobile communication technology and the increase in the telephone demand of developing countries with low telephone penetration rate. It was developed to be removed and developed as a "Fixed Subscriber", to supply to developing countries.

In addition, the narrowband wireless subscriber network system mainly processes voice, can process low-speed data, fax, etc., and in the case of voice, can provide a level of service equivalent to existing wired quality.

However, in the current WLL terminal, only data communication using a serial port is possible, and modem communication with an external modem (DCE; data communication equipment) is not performed.

Therefore, the present invention has been proposed to solve the above problems according to the prior art,

An object of the present invention is to use a V.22bis communication method, which is a modem protocol, through a tip-ring when a pay-phone is connected to a wireless subscriber network (WLL) terminal. A method of modem communication in a wireless subscriber network system that allows communication between the wireless subscriber network terminal and a public telephone to send and receive asynchronous data and to monitor and manage the state of the public telephone connected to the wireless subscriber network terminal. In providing.

Modem communication method in a wireless subscriber network system according to the present invention for achieving the above object,

A first step of determining whether a predetermined code for performing supervision of the public telephone is input in an off-hook state;

As a result of the determination, if the code for the monitoring and management of the public telephone is not input, the general call processing process is performed. If the code for the monitoring and management of the public telephone is input, the V between the modem and the public telephone of the WLL terminal is input. Starting an analog communication using the .22bis standard and determining whether the V.22bis communication is in a data transmission mode;

A third step of sending a dial-up command to a mobile station modem (MSM) of a wireless subscriber network terminal when the modem communication is in the data transmission mode as a result of the determination of the second step;

Performing asynchronous digital data call processing between the terminal of the wireless subscriber network system and an interworking function (IWF) to determine whether a transmission / reception path of the digital data is connected;

As a result of the determination in the fourth step, if the data transmission / reception path is connected, the data transmission mode is set to send and receive data with the monitoring center of the wireless subscriber network. It comprises a fifth step.

In addition, in the wireless subscriber network system according to the present invention for achieving the above object, a method for implementing a surveillance management function of a public telephone

Sending a dial-up command to the mobile station modem (MSM) of the wireless subscriber network terminal to interwork with the receiving modem,

A first step of the modem receiving the ring signal from the MSM, sending a message in response to the ring signal;

Determining whether the data call processing path is connected, ending the call if the data call processing path is not connected, and if connected, performing analog modem communication using the V.22bis standard;

It is determined whether the analog modem communication is in the data transmission mode and terminates the call if not in the data transmission mode. In the data transmission mode, the low speed data communication using the modem is performed in the data transmission mode until the call is disconnected. Performing a third step;

And determining whether or not the call has been cut.

1 is a block diagram of a wireless subscriber network system to which the present invention is applied,

2 is a flowchart illustrating an operation of a calling modem in a modem communication method in a wireless subscriber network system according to the present invention.

3 is a flowchart illustrating a receiving side modem operation in a modem communication method in a wireless subscriber network system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: payphone

11: WLL terminal

14: data network interworking device

15: Surveillance Center

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a method for implementing a monitoring management function of a public telephone in a wireless subscriber network system of the present invention will be described.

1 is a block diagram of a wireless subscriber network system to which the present invention is applied.

As shown, a pay-phone 10 connected to a WLL terminal 11 to perform analog modem communication with a WLL terminal, and a base station of a wireless subscriber network system connected to the payphone A WLL terminal 11 wirelessly connected to the base station 12, a base station (BTS) 12 receiving a wireless signal of the WLL terminal and providing a forward and reverse link, and a switching function of a wireless subscriber network system connected to the base station It is connected to the switch (MSC) 13 for performing the operation, the OM center 15 and the switch 13 connected to the switch 13 to perform the operation and management function of the wireless subscriber network system It consists of an IWF (Interwoking Function) 14 to perform a network interworking function.

In the wireless subscriber network system to which the present invention configured as described above is applied, since the WLL terminal and the base station are constituted by a radio link, an exchange 13 for supervisioning the pay-phone 10 and The WLL terminal 11 transmits and receives data wirelessly, and thus, the WLL terminal 11 and the public telephone 10 exchange CDMA asynchronous data (Asynchronus data) using the V.22bis standard.

Hereinafter, the operation of the calling modem during the communication procedure between the pay-phone and the WLL terminal using the V.22bis standard will be described.

First, when the calling modem is connected to the communication line, it must be in a state to receive a high frequency channel, that is, a high channel signal at a speed of 1200 bps (bit per second), and at a speed of 1200 bps. It must be in a state for transmitting a signal on a low frequency channel, that is, a low channel. The circuit 107 in the modem shall be energized according to the recommendations of V.25 specification and the modem shall initially remain silent. Here, the circuit 107 (Circuti 107) is a number for the circuit for each module in the modem and is a form for distinguishing the circuit portion in the modem.

Subsequently, the modem remains silent for 456 ± 10 ms after unscrambled binary 1 has been detected and after approximately 155 ± 10 ms has passed, and 00 at 1200 bps for 100 ± 3 ms. Transmit an unscrambled repetitive double dibit of 11; Here, scrambling means changing the arrangement of data or performing a mathematical process such that when a data is transmitted or received in a mobile communication system, only a specific receiver can receive the desired data. The dibit is 00 or 11 It refers to a data unit consisting of two bits.

Following the transmission of the unscrambled repetitive double dibit, the modem transmits binary 1 scrambled at 1200bps.

Next, if the modem detects scrambled binary 1 at 1200 bps for 270 ± 40 ms on the high channel, the handshake must continue. However, if unscrambled repetitive double dibits 00 and 11 are detected on the high channel at a speed of 1200bps, the modem will apply an On state to Circuit 112 after receiving this signal. .

The handshake means to agree to communicate at the highest standard rate among the speeds a transmit and receive modem can achieve. That is, modems installed at both ends of the line may have different transmission capacities, which means that the modems are notified of their capabilities and determine the maximum transmission speed that can be used during communication.

Subsequently, after 600 ± 10 ms after circuit 112 is turned on, the modem starts transmitting scrambled binary 1 at 2400 bps and the receiver 450 ± 10 ms after circuit 112 is turned on. The receiver must initiate a 16-way decision.

The modem then transmits scrambled binary 1 scrambled at 2400 bps for 200 ± 10 ms, followed by circuit 106 in response to circuit 105 and the modem should be ready to transmit data at 2400 bps. do.

Then, if 32 consecutive bits of scrambled binary 1 are detected on the high channel at 2400 bps, the modem should be ready to receive at 2400 bps and apply an On state to circuit 109.

Hereinafter, the operation of the receiving modem during the communication procedure between the pay-phone and the WLL terminal using the V.22bis standard will be described.

First, once the receiving modem is connected to the telephone line, it must be in a state of transmitting a signal in a high channel at 1200bps and in a state of receiving a signal in a low channel at 1200bps. And after transmitting the response signal sequence according to Recommendation V.25, the modem shall turn on circuit 107 and transmit a 1200 bps unscrambled binary 1.

Then, the handshaking continues if the modem detects a low-channel scrambled binary 1 or 0 at 1200bps for 270 ± 40ms. And if unscrambled repetitive double dibits 00 and 11 are detected on the low channel at 1200 bps, then at the end of reception of this signal, the modem shall apply an On state to circuit 112 and will not be scrambled. Non-repetitive dual dibit patterns 00 and 11 are transmitted for 100 ± 3 ms. It will then send a 1200 bp scrambled binary one.

Next, after 600 ± 10 ms after circuit 112 is turned on, the modem starts transmitting the scrambled binary 1 at 2400 bps, and 450 ± 10 ms after circuit 112 is turned on. The receiver must then initiate a 16-way decision.

Subsequently, when 1 bit of scrambled binary coded at 2400 bps for 200 ± 10 ms is detected at 2400 bps, the modem shall be ready to receive at 2400 bps and apply On to circuit 109.

Once a specific number (specific code for the payment supervision) is input through the tip-ring, the terminal starts an asynchronous call using the AT command, which is a modem control command. Modem communication between the payphone and the modem of the WLL terminal begins. When an asynchronous call is connected, a connection signal is sent to the Rx port of serial communication, called Universal Synchronus Asynchronus Receiver and Transmitter (USART) of the WLL terminal, that is, universal synchronous / asynchronous receiver and transmitter. When the modem receives the connection signal, it waits for the communication with the public telephone to end and then exchanges data with the monitoring center using the asynchronous data.

2 is a flowchart illustrating an operation of a calling modem in a modem communication method in a wireless subscriber network system according to the present invention.

A first step of determining whether a predetermined code for performing supervision of the public telephone is input in an off-hook state;

As a result of the determination, if the code for the monitoring and management of the public telephone is not input, the general call processing process is performed. If the code for the monitoring and management of the public telephone is input, the V between the modem and the public telephone of the WLL terminal is input. Starting an analog communication using the .22bis standard and determining whether the V.22bis communication is in a data transmission mode;

A third step of sending a dial-up command to a mobile station modem (MSM) of a wireless subscriber network terminal when the modem communication is in the data transmission mode as a result of the determination of the second step;

Performing asynchronous digital data call processing between the terminal of the wireless subscriber network system and an interworking function (IWF) to determine whether a transmission / reception path of the digital data is connected;

As a result of the determination in the fourth step, if the data transmission / reception path is connected, the data transmission mode is set to send and receive data with the monitoring center of the wireless subscriber network. Modem communication method in a wireless subscriber network system comprising a fifth step.

3 is a flowchart illustrating a receiving side modem operation in a modem communication method in a wireless subscriber network system according to the present invention.

The method of claim 1,

Sending a dial-up command to the mobile station modem (MSM) of the wireless subscriber network terminal to interwork with the receiving modem,

The modem receiving the ring signal from the MSM sends a message responsive to the ring signal;

Determining whether the data call processing path is connected, ending the call if the data call processing path is not connected, and if connected, performing analog modem communication using the V.22bis standard;

It is determined whether the analog modem communication is in the data transmission mode and terminates the call if not in the data transmission mode. In the data transmission mode, the low speed data communication using the modem is performed in the data transmission mode until the call is disconnected. Making a step;

And determining whether the call is disconnected and terminating the data call processing when the call is disconnected.

Modem communication method in the wireless subscriber network system according to the present invention as described above by the modem communication with the external modem through the tip-ring to the WLL terminal that can not perform modem communication, in any region where wireless communication is possible using this By having one-to-one communication with a modem and exchanging data with an opposite party, there is an effect of enabling wireless communication with many terminals requiring low-speed data communication.

In addition, since the present invention automatically stores inside the N-WLL terminal, the user can update the MP3 file without using an external device such as a serial port or replacing a memory module.

Claims (2)

In a wireless subscriber network system having a pay-phone, an external modem, a wireless terminal, and a monitoring center, A first step of determining whether a predetermined code for performing supervision of the public telephone is input in an off-hook state; As a result of the determination, if the code for the monitoring and management of the public telephone is not input, the general call processing process is performed. If the code for the monitoring and management of the public telephone is input, the V between the modem and the public telephone of the WLL terminal is input. Starting an analog communication using the .22bis standard and determining whether the V.22bis communication is in a data transmission mode; A third step of sending a dial-up command to a mobile station modem (MSM) of a wireless subscriber network terminal when the modem communication is in the data transmission mode as a result of the determination of the second step; Performing asynchronous digital data call processing between the terminal of the wireless subscriber network system and an interworking function (IWF) to determine whether a transmission / reception path of the digital data is connected; As a result of the determination in the fourth step, if the data transmission / reception path is connected, the data transmission mode is set to send and receive data with the monitoring center of the wireless subscriber network. Modem communication method in a wireless subscriber network system comprising a fifth step. The method of claim 1, Sending a dial-up command to the mobile station modem (MSM) of the wireless subscriber network terminal to interwork with the receiving modem, The modem receiving the ring signal from the MSM sends a message responsive to the ring signal; Determining whether the data call processing path is connected, ending the call if the data call processing path is not connected, and if connected, performing analog modem communication using the V.22bis standard; It is determined whether the analog modem communication is in the data transmission mode and terminates the call if not in the data transmission mode. In the data transmission mode, the low speed data communication using the modem is performed in the data transmission mode until the call is disconnected. Making a step; And determining whether the call is disconnected and terminating the data call processing when the call is disconnected.