KR20130033599A - Telephone line data comunication system - Google Patents

Abstract

PURPOSE: A telephone line data communications system is provided to use an OFDM(Orthogonal Frequency Division Multiplex) communications method in a telephone line or a copper line. CONSTITUTION: A medium access control unit receives an Ethernet signal. An OFDM modulation unit performs the OFDM modulation of a signal received by the medium access control unit. A signal amplifying unit amplifies a modulated signal. A telephone line impedance matching unit matches an output terminal of the signal amplifying unit with the impedance of an amplified signal delivering telephone line. The telephone line impedance matching unit matches with the impedance using a transformer having different winding ratios. [Reference numerals] (AA) DC blocking capacitor; (BB) Infinite impedance; (CC) 120 ohm impedance; (DD) Surge protection diode;

Description

Telephone line data communication system {TELEPHONE LINE DATA COMUNICATION SYSTEM}

The present invention relates to a communication system, and more particularly to a communication system for performing data communication over a telephone line.

In general, the mobile communication repeater has a configuration in which a plurality of remote repeaters are connected to one main repeater using a coaxial cable. 1 is a configuration diagram of a general mobile communication repeater. In order to install a network equipment such as a WLAN AP, a web camera, or a femtocell in the conventional mobile communication repeater, a separate network construction is required from the existing coaxial cable.

In addition, in general, in the case of installing a network camera and CCTV camera, etc., in order to install a single camera, a coaxial cable or a UTP cable should be wired. Each time a camera is added, individual cable routing is required, as shown in FIG. 2 is a configuration diagram of a conventional IP camera connection method. Referring to Figure 2, each camera has a problem in that the construction cost is high because the LAN cable must be wired separately, and the power must be wired separately.

Also, in order to install network products, LAN cable should be wired and power cable should be additionally wired. PoE was introduced to solve this problem. PoE is a technology that uses 4 wires for data communication and 4 wires for power supply in 8 UTP cables. The solution provides + 24V power and ground wires on four strands of wire to provide power and Ethernet signals simultaneously to remotely located network devices. This PoE method is widely used to provide the advantage of not needing a separate power supply, but has a problem that the transmission distance is limited to within 100m.

The present invention has been made to solve the above-mentioned conventional problems, the network device is installed in the conventional mobile communication repeater without a separate network construction, and do not have to perform a separate cable wiring for a plurality of IP cameras, PoE An object of the present invention is to provide a communication system that can effectively extend the distance of.

In order to achieve the above object, a telephone line data communication system according to the present invention includes a medium access control unit, an OFDM modulator, a signal amplifier, and a telephone line impedance matching unit.

The medium access control unit receives an Ethernet signal, the OFDM modulation unit performs OFDM modulation on the signal received from the medium access control unit, the signal amplification unit amplifies the modulated signal, and the telephone line impedance matching unit transmits the output terminal and the amplified signal of the amplification unit. Match the impedance of the telephone line to be used. At this time, the matching of the impedance is performed by using a transformer having a different turns ratio.

As described above, the OFDM communication method can be used for a telephone line or a copper wire by applying an impedance matching method using a transformer having a different turns ratio to the OFDM modulation method.

In addition, the telephone line data communication system may further include a repeater cable impedance matching unit for matching the output terminal of the telephone line impedance matching unit and the impedance of the mobile communication repeater cable, and an RF coupler for coupling the cable impedance matching unit to the mobile communication repeater cable. In this case, the repeater cable impedance matching unit may convert the 120-ohm TLC signal into a 50-ohm TLC signal.

By such a configuration, it is possible to install network equipment such as a WLAN AP, a web camera, or a femtocell without additional network construction by using a coaxial cable of an existing repeater.

In addition, the telephone line data communication system may further include additional transformers and capacitors for voice signals connected in parallel to the secondary side of the transformer.

With this configuration, power, voice signal, and TLC high-speed data can be sent to one telephone line at the same time, and multiple devices can be simultaneously connected to one telephone line, thereby significantly reducing construction costs.

In addition, the telephone line data communication system may further include a voltage supply connected to the winding of the secondary side of the transformer through a ground tab.

With this configuration, it is possible to shorten the construction cost and duration by enabling the transmission distance of the PoE to at least 300m by solving the 100m distance limitation, which was a disadvantage of the existing PoE.

According to the present invention, an OFDM communication method can be used for a telephone line or a copper wire by applying an impedance matching method using a transformer having a different turns ratio to the OFDM modulation method.

In addition, it is possible to install network equipment such as a wireless LAN AP, a web camera, or a femtocell without additional network construction by using a coaxial cable of an existing repeater.

In addition, power, voice signal, and TLC high-speed data can be sent to one telephone line at the same time, and multiple devices can be simultaneously connected to one telephone line, thereby significantly reducing construction costs.

In addition, by solving the 100m distance limitation, which was a disadvantage of the existing PoE, the transmission distance of the PoE can be made at least 300m, thereby reducing the construction cost and period.

1 is a configuration diagram of a general mobile communication repeater
2 is a configuration diagram of a conventional IP camera connection method
3 is a communication table comparison table using a telephone line.
4 is a table showing TLC technical specifications.
5 is a general configuration diagram of the TLC technology
6 shows a hybrid circuit that is a key element of TLC
7 is a diagram illustrating a configuration of combining a wireless communication repeater and a wireless LAN using TLC
8 is a signal flow when combining a wireless communication repeater and a wireless LAN using TLC
9 is a configuration diagram for applying a TLC to a coaxial cable
10 is a circuit diagram for applying a TLC to a coaxial cable
11 is a connection diagram of an IP camera using TLC
12 is a TLC circuit configuration for transmitting voice and data at the same time
13 is a configuration diagram of the combination of PoE and TLC
14 is a TLC circuit configuration for supporting PoE

As a data communication method using a telephone line, conventional methods such as ADSL, VDSL, and Home PNA are used. ADSL can transmit Ethernet data over a telephone line up to 7-8km, and VDSL can transmit up to 100Mbps Ethernet data over 300m over a telephone line. These ADSL and VDSL methods support 1: 1 communication only, so multiple access communication is not possible.

Unlike ADSL and VDSL, Home PNA 2.0 is a technology designed for home network configuration. It supports multiple connections and can transmit data of 50Mbps or more up to 300m over a telephone line. The recently developed Home PNA 3.0 can transmit up to 200Mbps of data and 128 devices can be connected simultaneously. In terms of transmission distance, it is known to not exceed 500m.

Such ADSL, VDSL, Home PNA, etc. are all designed to transmit data through the telephone line. Here, the telephone line generally refers to a TIV cable or a CPEV cable. ADSL, VDSL, Home PNA, etc. are designed to be optimized for TIV cable and CPEV cable, thus providing optimal performance for these telephone lines.

On the other hand, the TLC technology possessed by the applicant of the present invention is a multiple access communication method using a telephone line, and enables high-speed data communication by applying an Orthogonal Frequency Division Multiplex (OFDM) technique widely used in wireless communication to wired communication. That's the way it is.

The TLC technology is applied by the applicant of the present invention, "Apparatus and System for Simultaneous Transmission of Voice and Data Signals: 10-0709617", "Power Over Ethernet-based LAN Relay and Powerover Ethernet Hybrid Relay Device: 10-0756244", and " An interphone line network system using TLC technology and its application service: 20-2009-0002542 ”, a hybrid circuit for applying OFDM modulation to a telephone line and simultaneously transmitting voice and data is a major technical element.

TLC technology shows excellent communication performance not only in general telephone lines but also in various types of wires such as PVC telephone lines, speaker lines, and coaxial cables. The TLC technology developed by the applicant of the present invention can transmit up to 1.5 km on a general telephone line and the maximum transmission speed is 200 Mbps. In addition, up to 64 devices can communicate at the same time.

The following table compares the TLC technology possessed by the applicant of the present invention with a communication method using a telephone line that is currently developed and commercially available. 3 is a communication table comparison table using a telephone line.

Such TLC technology was selected as a research on “Standardization of Home Network Device Technology Using Telephone Line Carrier Communication” from “Information and Communication Standardization Project” hosted by Korea Information and Communication Standards Association in 2008. It was also selected as a joint industry-university research and development project, and technology development was promoted.

The TLC technology developed by the present applicant is a multiple access communication method using a telephone line. This technology is a method that enables high-speed data communication by applying Orthogonal Frequency Division Multiplex (OFDM) technique widely used in wireless communication to wired communication.

The most important element of TLC technology is to obtain more stable and superior performance by applying OFDM modulation method having excellent transmission performance to wired in noisy wireless environment.

TLC technology uses Time Division Duplex (TDD), and up to 64 devices can be connected at the same time. The maximum transmission rate is 200Mbps based on the physical layer, which can be considered as 100Mbps in both directions. The actual transfer rate is about 85Mbps. The transmission distance can be up to 1.5km from the telephone line. The specification for the currently implemented TLC technology is shown in FIG. 4. 4 is a table showing the TLC technical specifications.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

5 is a representative configuration of the TLC technology possessed by the applicant of the present invention. 5, the Ethernet signal is transmitted to the MAC. MAC is an abbreviation of Media Access Controller and is a part that controls multi-access communication of TLC technology.

In TLC, 64 devices can communicate simultaneously and transmit and receive data through TDD (Time Division Duplex). Control in this regard is performed in the MAC. Data passing through the MAC is modulated and demodulated via an OFDM modem. The modulated OFDM signal is transmitted to a telephone line or a copper line through an amplifier circuit called an analog front end (AFE).

The configuration so far is the same as general OFDM communication used in wireless communication. A key element of the company's TLC technology is the hybrid circuit for transmitting general OFDM communications over telephone and copper lines.

Hybrid circuits are impedance conversion circuits for transmitting OFDM modulated signals to telephone lines (impedance 120 ohms). When a typical OFDM modulated signal passes through the AFE, the final output impedance is high, close to infinity. In this way, if the impedance near infinity meets the telephone line (impedance 120 ohms), signal distortion occurs due to the impedance mismatch.

The hybrid circuit, which is a core technology of TLC, uses a circuit as shown in FIG. 6 to convert an infinite impedance into 120 ohms. Referring to FIG. 6, when the impedance of the AFE is infinite and the impedance of the telephone line is 120 ohms, transformers having different turns ratios are used to match the impedance of the AFE.

The use of transformers with different turns ratios instead of the general impedance matching circuit for impedance matching is a key element of the TLC technique devised by the present applicant.

If a typical impedance matching circuit is used to match infinite impedance and 120 ohm impedance, a large number of resistors, inductors, and capacitors are required, which makes it difficult to obtain a complex and uniform impedance match.

On the other hand, using transformers with different turns ratios, the impedance can be easily matched. Impedance matching schemes using transformers with different turns ratios are widely used in wired transmissions, but they have not been applied in general wireless communication such as OFDM modulation.

In addition, the present applicant is a wired OFDM communication method that can use a wireless OFDM communication method for a telephone line or a copper wire by using an impedance matching method using a transformer having a different turns ratio that is frequently used in a wireline to an OFDM modulation method widely used for wireless communication. TLC was designed.

In addition, the present invention proposes a method for transmitting a WLAN signal using a coaxial cable of an existing mobile communication repeater using the TLC technology.

In the case of the existing mobile communication repeater, the coaxial cable is connected between the repeater and the antenna, and only the mobile communication signal is transmitted to the coaxial cable, and thus the frequency band of 0 to 200 MHz is mostly empty.

The present invention proposes a method of extending a wireless LAN or providing another network service by simultaneously transmitting a TLC signal in a 2 to 70 MHz band to a coaxial cable for a repeater using a coaxial cable for a mobile communication repeater.

Through this, telecommunications operators have the advantage that they can provide various application services such as WLAN expansion, web camera installation and femtocell installation without additional construction costs by utilizing the coaxial cable for the existing mobile communication repeater.

An application service for transmitting a TLC signal using a coaxial cable connected between a repeater and an antenna, a repeater and a repeater of a conventional mobile communication repeater will be described in detail as follows.

The application service applying TLC to coaxial cable of mobile communication repeater was devised in the following background. In general, the mobile communication repeater has a configuration in which a plurality of remote repeaters are connected to one main repeater using a coaxial cable as shown in FIG. 1.

Since only the mobile communication signal is transmitted to the coaxial cable, the frequency band of 0 to 400 MHz is not used and can be called an empty frequency band. The main goal of the first application service is to transmit TLC signals in the 2 to 70 MHz frequency band together in the empty coaxial cable frequency band.

In this case, as shown in FIG. 7, it is possible to install network equipment such as a WLAN AP, a web camera, or a femtocell without a separate network construction by using a coaxial cable of an existing repeater.

As shown in FIG. 7, the mobile communication signal of the repeater and the signal of the TLC modem can be simply combined by using a widely used RF signal broadband 'combiner', and on the other side, the mobile communication signal and the TLC using the same 'combiner'. You can isolate the signal.

Referring to FIG. 8, a smart phone using a wireless LAN has a configuration connected to a network through a wireless LAN AP, a TLC modem, and a general voice mobile phone has a configuration connected to a base station using an existing repeater.

In the case of using such a configuration, a communication service provider can use various repeater network services. For the service provider, it is possible to significantly reduce maintenance costs by expanding the wireless LAN area, installing a web camera, or installing a femtocell using only a TLC modem and a combiner without additional construction cost.

9, the Ethernet signal is converted into a signal of the 2 ~ 70MHz band passing through the TLC modem. In this case, the TLC modem is transmitted through a telephone line, so the impedance is 120 ohms.

However, RF technologies such as general mobile communication are mostly 50 ohm impedance. Therefore, transmitting TLC signal directly to coaxial cable causes impedance mismatch. To solve this, pass a 120 Ohm-50 Ohm Impedance Converter.

'120 Ohm-50 Ohm Impedance Converter' can be easily designed using a conversion coil having a different turns ratio as shown in FIG. 10. The TLC signal, converted to 50 ohm impedance, is transmitted in combination with the mobile communication signal at the RF coupler.

In addition, the present invention proposes a method for simultaneously transmitting the AC power, voice signal, and TLC signal by applying the TLC technology to PVC telephone lines. Through this, unlike the existing network construction method, it is possible to drastically reduce the network construction cost by simultaneously transmitting AC power, voice signal, and high-speed data signal to one PVC telephone line.

The method of transmitting AC power or DC power, voice signal, and TLC signal simultaneously using a telephone line and a general copper wire and its application service will be described in detail as follows.

The simultaneous transmission of AC and DC power, voice signals, and TLC signals using PVC telephone lines (also known as beep lines) was devised in the following context.

In general, in case of installing network camera and CCTV camera, coaxial cable or UTP cable should be wired to install one camera. Each time a camera is added, individual cable routing is required, as shown in FIG.

Referring to Figure 2, each camera has a problem in that the construction cost is high because the LAN cable must be wired separately, and the power must be wired separately.

However, when using the TLC technology, as shown in FIG. 11, power, voice signal, and TLC high-speed data can be simultaneously transmitted to one telephone line, and a large number of devices can be simultaneously connected to one telephone line, thereby significantly reducing construction costs. Can be reduced.

As such, in order to simultaneously transmit a TLC signal, a power supply, and a voice signal using a general telephone line or a copper wire, a configuration as shown in FIG. 12 should be made.

FIG. 12 illustrates the application of additional transformers and capacitors for coupling voice signals to a hybrid circuit, which is the core technology of TLC mentioned in FIG. By using this circuit, it is possible to transmit voice and TLC signals simultaneously to one telephone line or copper line.

In addition, the present invention proposes a PoE extension technique using TLC.

In order to solve the 100m distance limitation, which is the biggest disadvantage of the Power Over Ethernet (PoE) system, a circuit and an application service that increase the transmission distance of the PoE system by more than 300m using TLC technology will be described in detail as follows.

Power over Ethernet (PoE) distance extension services using TLC technology were designed to: In general, in order to install a network product, the LAN cable should be wired and additionally, the power cable should be wired. PoE was introduced to solve this problem. PoE is a technology that uses 4 wires for data communication and 4 wires for power supply in 8 UTP cables. The solution provides + 24V power and ground wires on four strands of wire to provide power and Ethernet signals simultaneously to remotely located network devices.

This PoE method is widely used to provide the advantage of not needing a separate power supply, but has a problem that the transmission distance is limited to within 100m.

In the present invention, as shown in FIG. 13, in order to extend the transmission distance of PoE, an application service and a method for extending the transmission distance to at least 300m by inserting a TLC modem in the middle are devised.

First, the Ethernet signal from the PoE passes through the TLC modem and is converted into a TLC signal in the 2-30 MHz band. In addition, power from the PoE is routed through the TLC modem and can be delivered to the phone line. The TLC modem transmits TLC signals and power simultaneously over the telephone line and transmits at least 300m. The TLC modem located on the other side converts the TLC signal back to the Ethernet signal and transmits it to PoE, and the power from the TLC modem is supplied to the PoE power again.

Through this process, the PoE, which was previously limited to 100m, can transmit at least 300m using TLC, resulting in a dramatic improvement in network construction efficiency.

For PoE extension service using TLC, a configuration as shown in FIG. In order to transmit power through the existing telephone line or copper wire, a power supply is provided as shown in FIG. Using this connection, it is possible to transmit TLC signals and power simultaneously on one telephone line.

In the present invention, the application of TLC technology has been extended to various application services.

The biggest expense in expanding the wireless LAN area, expanding the mobile communication femto cell, and installing CCTV cameras and web cameras is the construction cost. In the case of Korean telecommunications operators, the purchase price of a WLAN AP is about 30,000 won per unit, but the construction cost of installing a single WLAN AP is about 200,000 won. This is because labor costs have risen sharply, material costs for construction have increased, and buildings that are difficult to construct are steadily increasing.

In the case of using an application service for transmitting a TLC signal through the coaxial cable devised in the present invention, a communication service provider can extend a WLAN AP by using a coaxial cable installed for a mobile communication repeater, without additional construction cost. It can have the advantage of simply installing a WLAN AP. This can reduce costs by at least 30% compared to installing a WLAN AP in the conventional manner. Overseas, the installation cost of the network is higher, so the method of applying the TLC technology devised in the present invention to the coaxial cable may be further spotlighted.

The second application service, which is the simultaneous application of TLC signals, power, and voice signals through PVC telephone lines, can be applied to more diverse fields. In case of installing CCTV and web cameras, cable work is required to install one camera. In addition, there is a problem of additional power construction.

On the other hand, when TLC technology is used, power, voice, and TLC signals are simultaneously transmitted to one PVC telephone line, and multiple network devices can be simultaneously connected to one PVC telephone line, thereby significantly reducing construction costs. . It can also be widely used when military installations require field networks or industrial networks need emergency networks.

PoE extender using TLC, the third application service, can solve the 100m distance limitation, which is a disadvantage of existing PoE, and make PoE transmission distance at least 300m.

Although the present invention has been described in terms of some preferred embodiments, the scope of the present invention should not be limited thereby but should be modified and improved in accordance with the above-described embodiments.

Claims (5)

A medium access control unit receiving an Ethernet signal;
An OFDM modulator for performing OFDM modulation on the signal received from the medium access controller;
A signal amplifier for amplifying the modulated signal; And
A telephone line data communication system including a telephone line impedance matching unit for matching an output terminal of the amplifier and an impedance of a telephone line to which the amplified signal is to be transmitted.
The telephone line impedance matching unit is a telephone line data communication system, characterized in that for matching impedance using a transformer having a different turns ratio. The method of claim 1,
A repeater cable impedance matching unit for matching an output terminal of the telephone line impedance matching unit with an impedance of a mobile communication repeater cable; And
And an RF coupler for coupling the cable impedance matcher to the mobile repeater cable. The method of claim 2,
The repeater cable impedance matching unit converts a 120 ohm TLC signal into a 50 ohm TLC signal. The method of claim 1,
And a transformer and a capacitor for a voice signal connected in parallel to the secondary side of the transformer. The method of claim 1,
And a voltage supply connected to the winding of the secondary side of the transformer through a grounding tab.

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