JP2002354439A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand a network system easily. SOLUTION: The network system utilizes radio and a community cable. A first antenna apparatus 41 is provided at a central station 450 such as a CATV station, or the tip of an optical fiber being extended from the central station 40. In addition, each enterprise 30 having the community system has a second antenna apparatus 21 for communicating with the first antenna apparatus 41 at the central station, and a third antenna apparatus 22 for communicating with a fourth antenna apparatus 41 of a consumer 50. Then, frequency converters 23 and 52 are provided directly below each antenna apparatus, and the radio frequency band of each antenna apparatus is frequency-converted mutually to a prescribed band (empty band) of the community system. As a system, communication by radio among the central station 40, each enterprise 30, and each consumer 50, and communication mainly by cables within each enterprise 30 expand the network easily. In addition, giving repeat functions to each enterprise can also expand the network system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a communication network system. In particular, the present invention relates to a network system that performs wired communication in a specific area such as an office and wirelessly communicates outside a specific area. INDUSTRIAL APPLICABILITY The present invention is applicable to a wired / wireless LAN and a wired / wireless WAN using a TV co-listening cable and wireless.

[0002]

2. Description of the Related Art Conventionally, there is a network system using a CATV co-listening system. It is generally called a local area network (hereinafter, referred to as LAN), connects a plurality of terminal devices to a CATV trunk cable (optical fiber) deployed in the city, and connects between terminal devices or between a terminal device and a central device. This is a system for transmitting and receiving data between the devices. FIG. 5 shows a conventional CATV network system.

[0003] For example, a conventional CATV network system includes a central unit 12 provided in a CATV station 120.
2. An optical fiber cable 125 which is a trunk cable connected to the central device 122, an optical node device 130 provided at a predetermined position of the optical fiber cable 125, and a branch optical fiber cable 12 branched from the optical node device 130.
4. Branch network 150 such as a business office connected to branch optical fiber cable 124, and branch coaxial cable 1
26 is connected to the home network 140. Note that the CATV station 120 has an Internet interface 121, and the central device 122 is connected to the Internet network 100 via the Internet interface 121.

A premises network 150, which is a premises co-listening system at a business office or the like, includes a photoelectric converter 151 for mutually converting an optical signal into an electric signal, and a branch / distribution for branching / distributing the signal converted by the photoelectric converter 151. 155, a terminal device 152 and a TV receiver 153 connected to the branch / distributor 155. A home network 140, which is a home co-listening system, is provided with a branch coaxial cable 126.
/ Distributor 1 for branching / distributing a high-frequency signal propagated through
41, terminal device 142 connected to branch / distributor 141
And a TV receiver 143. In both networks, the terminal devices 152 and 142 are, for example, computer devices, and convert high-frequency signals into baseband signals.
Alternatively, it has cable modems 154 and 144 for modulating and demodulating a baseband signal into a high-frequency signal.

[0005] As described above, the conventional CATV network system is mainly connected to the city and indoors (in the premises and at home) by wire (including optical fiber cables). In recent years, wireless communication has begun to spread only indoors, but between the private network 150 and the home network 140 are still connected by the optical fiber cable 125, the branch optical fiber cable 124, and the branch coaxial cable 126. ing. The transmission system used in the CATV network system is, for example, a broadband system in which a high-frequency signal (RF signal) is frequency-multiplexed and transmitted.
The upstream high-frequency signal has, for example, a band of 10 MHz to 55 MHz,
A band of 70 MHz to 770 MHz is assigned to the downstream high-frequency signal, and data signals are transmitted and received as upstream and downstream signals using both bands.

[0006]

However, in a conventional computer network system using a co-listening system, a branch line is extended from a trunk optical fiber cable called a "backbone" by an optical fiber cable or a coaxial cable. That is, the system is connected to each terminal device by wire. In addition, this wired connection requires an installation cost, especially when the branch line is an optical fiber cable, and is a so-called “last one mile” problem, which is a factor preventing further spread of the network. That is,
The network could not be easily expanded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to use an existing co-listening system for wired communication within an office, and to establish communication between offices and other networks. It is to solve the so-called 'last one mile' problem as wireless communication. That is, the network can be expanded simply by providing an antenna device and a frequency conversion device in each of the co-listening systems. Also, it is intended to facilitate the incorporation into the WAN. or,
An object of the present invention is to provide an access point device capable of connecting a large number of wireless terminal devices to the co-listening system, and to provide a more flexible network system.

[0008]

According to the first aspect of the present invention, there is provided a network system including a central unit and a plurality of terminal units, each of which has a business function. In a network system using a TV co-listening cable at a location, a first antenna device is provided on the central device side, and each business office has a second antenna device for communicating with the central device, and an input / output signal of the second antenna device is predetermined. A frequency conversion device for converting the signal into a band signal and inputting / outputting to / from a TV listening cable of each office is provided, and the terminal device of each office communicates using the TV listening cable and / or the second antenna device. It is characterized by.

[0009] The first antenna device provided in the central unit communicates with the second antenna device provided in each office. For example, communication is performed by modulating a 2.4 GHz carrier. For example, when transmitting data from the central unit,
For example, a carrier of 2.4 GHz is modulated with data and transmitted from the first antenna device. The wirelessly transmitted signal is received by the second antenna device of each business office, converted to a predetermined frequency by a frequency conversion device, and transmitted as a predetermined band signal to the TV common cable network. The predetermined band is, for example, a frequency up to an upper limit frequency of the TV common listening cable. For example,
900MHz if TV co-listening cable is coaxial cable
To several GHz are selected. Then, the predetermined band signal transmitted to the TV common listening cable is demodulated by the modem of each terminal device. Thereby, data from the central device is received.

Conversely, when data is transmitted from each terminal device, each terminal device modulates a carrier in a predetermined band with data and transmits the modulated data to a TV common listening cable (predetermined band signal). The predetermined band signal follows the reverse path and is input to the frequency conversion device. On the contrary, the frequency converter converts the carrier frequency of the predetermined band signal to, for example, 2.4 GHz. Then, the signal is transmitted from the second antenna device to the first antenna device wirelessly at a carrier frequency of 2.4 GHz. The first antenna device receives and demodulates it. That is, data is transmitted. That is, the terminal device connected to the TV common listening cable can communicate not only with the indoor device but also with the terminal devices at other offices. That is, wired communication is performed indoors, and wireless communication is performed outdoors (between offices). This eliminates the need to network each business office with a new cable. Therefore, a highly flexible network system can be constructed. The frequency conversion device also includes a buffer device having the same input and output frequencies.

According to a second aspect of the present invention, the first antenna device is connected to a tip of an optical fiber extending from the central device via a photoelectric converter. With this configuration, the data signal from the central device is sent to the photoelectric converter as an optical signal, and the optical signal is converted into an electric signal. The data signal converted into the electric signal is transmitted to each office by the first antenna device. Conversely, the data signal transmitted from each office is received by the first antenna device, converted into an optical signal by a photoelectric converter, and transmitted to the central device by an optical fiber. That is, the communication distance can be easily increased without increasing the output of the first antenna device. Also, there is no need to lay optical fibers at each business office. Therefore, the network system is excellent in convenience.

According to the third aspect of the present invention, the second antenna device has an address. If the addresses match, the second antenna device transmits the received signal to the subsequent frequency conversion device. It is characterized in that it is amplified and transmitted to a two-antenna device. This is a configuration in which the second antenna device has an address and distributes the address according to the address of the received data signal. For example, if the addresses match, there is no need to send the data signal to another business location. Conversely, if the addresses do not match, there is no need to send it to the terminal device in the business establishment.
Therefore, it becomes a power saving type network system. Further, this configuration is a configuration in which data signals are sequentially transferred to adjacent business offices without an optical fiber, for example. For example, if the distance between offices is several kilometers, the communication area can be further increased. That is, a network service can be provided to more customers.

According to a fourth aspect of the present invention, the frequency conversion device includes a third antenna device for communicating with a terminal device in a nearby area. When the data signal is input from the first antenna device, the data signal is amplified and converted to the third signal without frequency conversion by the frequency conversion device.
The signal is transmitted from the antenna device to a neighbor. When a predetermined band signal is input to the frequency conversion device from the TV co-listening cable, the frequency conversion device sets the carrier wave frequency to, for example, 2.
The signal is converted to 4 GHz and transmitted from the third antenna device to a nearby area.

When a data signal is input from the third antenna device, that is, when a data signal is transmitted from a terminal device of a nearby customer, the data signal is received by the third antenna device. If the destination of the data signal is outside the office, the frequency conversion device amplifies the data signal without frequency conversion and transmits the amplified signal to the central device. As a result, a nearby customer can communicate with a terminal device in another area. If the destination is inside the office, it is converted to a predetermined band by the frequency conversion device and transmitted to the TV common listening cable. As a result, a nearby customer can communicate with the terminal device of the business establishment.
Therefore, the network system expands the communication area around each office. The neighborhood area is, for example, the third area.
It means a small area within a radius of several hundred meters from the antenna device. That is, a network service can be provided to a customer within several hundred meters from the third antenna.

According to the network system of the fifth aspect, the frequency conversion device is provided at the subsequent stage with the TV antenna device, the received TV signal and the data signal converted by the frequency conversion device being multiplexed, and the TV audio cable is connected. And a multiplexer for transmitting the signal to the receiver. This configuration is for TV
A TV signal received by the antenna device and a data signal frequency-converted by the frequency conversion device are multiplexed by a multiplexer to form a TV signal.
This is a configuration for transmitting to a common listening cable. That is, if a filter for extracting a frequency up to about 800 MHz and a TV device are installed in the TV co-listening cable at the latter stage of the multiplexer, the TV is connected.
Reception is enabled. Further, if a terminal device having a filter for extracting a predetermined band, for example, a filter for extracting a frequency of 900 MHz or more, and a modulator / demodulator is installed in the TV co-listening cable at the subsequent stage of the multiplexer, data communication becomes possible. That is, both TV reception and data communication can be performed.

According to the network system of the sixth aspect, a wired LA is provided at any point of the TV common listening cable.
N and a first access point device for connecting the wireless terminal device. This configuration is based on the T
This is a configuration in which the V common listening cable is extended wirelessly. That is, T
A number of terminal devices are wirelessly connected downstream of the first access point device connected to the V common listening cable. That is, more terminal connections can be made possible. In addition, since the terminal device can communicate wirelessly, its arrangement can be flexibly changed within a range where radio waves can reach. Therefore, a network system having excellent flexibility can be constructed.

According to the network system of the seventh aspect, the second access point device for mutually converting a predetermined band signal into a radio signal and / or a baseband signal conforming to the Ethernet specifications at any place of the TV common cable. It is characterized by having. This second access point device is a three-way input / output device. For example, one of the data signals input in a predetermined band from the upstream is converted into a baseband signal and transmitted downstream, and the other is, for example, 2.4G.
Hz and transmitted outside the TV common listening cable. vice versa,
One of the signals input as a baseband signal from the downstream is transmitted upstream with a modulated signal of a predetermined band, and the other is transmitted outside the TV co-listening cable by, for example, 2.4 GHz radio. Further, for example, one of the signals input wirelessly at 2.4 GHz is converted into a baseband signal and transmitted downstream, and the other is transmitted upstream with a modulated signal of a predetermined band. That is, if this second access point device is provided,
For example, a terminal device that communicates with a baseband signal can be directly connected. Also, a wireless communication terminal device can be used. Therefore, a LAN can be formed for terminal devices having various communication formats.

According to the network system of the present invention, a plurality of bypass circuits for bypassing a predetermined band signal are provided at the subsequent stage of the multiplexer, and the plurality of bypass circuits are provided with a second access point device. Features.
In this configuration, a predetermined band signal (data signal) is distributed to more terminal devices. That is, a bypass circuit is provided after the multiplexer, that is, a bypass circuit in which only a predetermined band signal is branched into a plurality of signals just before the input to the TV common listening cable. This bypass circuit can be configured, for example, by disposing two demultiplexers in opposition and inserting two more opposing distributors into one of the demultiplexed paths (data paths). The bypass circuit is provided with a second access point device. Since the second access point device can convert a predetermined band signal into a radio signal and a baseband signal, the second access point device can include a terminal device suitable for those communication systems. Therefore,
Large-scale LA can be connected to more terminal devices
N can be formed.

According to a ninth aspect of the present invention, a plurality of second access point devices provided in a plurality of bypass circuits are provided downstream of a plurality of second access point devices. And a second access point device for converting the baseband signal condensed to the second band into a predetermined band signal. This configuration is a configuration in which second access point devices are provided in a plurality of bypass circuits, and are switched by a subsequent line concentrator, which is a so-called hub.

For example, when a data signal is transmitted from the downstream of the TV listening cable, if the communication destination is within the business office, the data signal is switched by the concentrator without going back to the upstream second antenna device, that is, the communication area. Is enlarged and transmitted to the target terminal device. Conversely, if the signal is a received signal from the second antenna device or the third antenna device, the received signal is transmitted to the target terminal device by the plurality of second access point devices and the concentrator. That is, the communication system expands the communication area. Also, for example, if a plurality of second access point devices are provided at different places of the business office and the second access point devices are sequentially switched, the wireless terminal device can always communicate. In other words, communication can be performed even during movement. A so-called roaming function can be provided. Therefore,
A highly convenient network system that enables mobile communication can be realized.

According to the tenth aspect of the present invention, the consumer under the third antenna device transmits the fourth antenna communicating with the third antenna device to the TV co-listening system including the TV antenna device and the TV co-listening cable. Equipment and
A frequency conversion device for converting the input and output of the fourth antenna device into a predetermined band signal;
And a multiplexer for transmitting the signal to the V common listening cable. The fourth antenna device communicates with a third antenna device of a nearby office. For example, when the signal is received from the third antenna device, for example, a 2.4 GHz received signal is converted into a predetermined band by a frequency conversion device. The predetermined band is, for example, a frequency up to an upper limit frequency of the TV cable. For example, if the TV cable is a coaxial cable, 900 MHz to several GHz is selected. Therefore, T
If you connect a terminal device with a modem to the V cable,
The data can be received.

Conversely, if a terminal device is connected to the TV cable, data can be transmitted. For example, the terminal device modulates a carrier in a predetermined band with data and transmits the modulated data to a TV cable. The predetermined band signal follows the reverse path and is input to the frequency conversion device. On the contrary, the frequency conversion device changes the carrier frequency of the predetermined band to, for example, 2.4 G
Convert to Hz. Then, the fourth antenna device wirelessly transmits to the third antenna device at the carrier frequency of 2.4 GHz.
Data from the terminal device is transmitted in this manner.

As described above, if the terminal device having the modem is connected to the TV cable, it is possible to communicate with the terminal device at a nearby office. Further, it can be connected to the office network by another antenna device (second antenna device) in the nearby office. That is, it can be connected to a WAN. If the business establishment is connected to another network, the customer can receive, for example, an Internet service. This eliminates the need for the customer to lay a wire such as an optical fiber or a coaxial cable and connect to a nearby network, for example. That is, an excellent network system can be used at low cost. If the transmission distance by the TV cable is short, the input and output frequencies of the frequency converter may be the same. If the distance is short, communication is possible even on the order of several GHz. That is, the frequency conversion device may be a simple buffer device.

According to the network system of the eleventh aspect, the third access point device having the same specifications as the first or second access point device is provided at any point of the TV listening cable of the customer. It is characterized by. As a result, the consumer can wirelessly connect a large number of terminal devices to the business office LA.
N. Therefore, it is possible to provide a user with a more convenient LAN or WAN.

According to a twelfth aspect of the present invention, the communication system between the third antenna device and the fourth antenna device is a communication system using a modulation method having high noise resistance. For example, a multi-carrier transmission scheme represented by a spread spectrum communication scheme and an orthogonal frequency multiplexing modulation scheme (OFDM) can be adopted. The spread spectrum communication system is a communication system that is resistant to noise that performs communication by dispersing frequencies. The orthogonal frequency multiplexing modulation method has a high transmission capacity per frequency band and is resistant to the influence of reflected waves and noise, so that it is expected to be widely used in future data communication. Thereby, the terminal device of the business office and the terminal device of the consumer can perform data communication with high quality.

According to a thirteenth aspect of the present invention, the communication system between the first antenna device and the second antenna device is a communication system using a modulation system having high noise resistance. For example, a multi-carrier transmission scheme represented by a spread spectrum communication scheme and an orthogonal frequency multiplexing modulation scheme (OFDM) can be adopted. The spread spectrum communication system is a communication system that is resistant to noise that performs communication by dispersing frequencies. The orthogonal frequency multiplexing modulation method has a high transmission capacity per frequency band and is resistant to the influence of reflected waves and noise, so that it is expected to be widely used in future data communication. As a result, the central device and the terminal device of the business office can perform data communication with high quality. Of course, if all of the communication systems between the third antenna device and the fourth antenna device are spread spectrum communication systems, high quality communication can be performed between all terminal devices and between all terminal devices and the central device.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following examples. (First Embodiment) FIG. 1 shows a network system of the present embodiment. The figure is a configuration block diagram. The network system according to the present embodiment is a network system including a central office 40 such as a television station and a telephone office, a business office 30, and a customer 50. Usually, there are a plurality of establishments 30 and customers 50.

The central office 40 is a system that includes a central unit 42 and a first antenna unit 41 and communicates with each business office 30. The office 30 is, for example, an apartment house having a TV co-listening system, and includes a TV antenna device 24 as a common antenna, a coaxial cable 26 as a TV co-listening cable, a distributor 31, and a plurality of TV devices 32. Usually, a TV signal is received by the co-listening system. In the present embodiment, a second antenna device 2
It is characterized by including a first antenna device 22, a third antenna device 22, a frequency conversion device 23, a multiplexer 25, a modem 33, a terminal device 34, a first access point device 35, and a wireless terminal device 36. In addition, the part enclosed by the broken line shows the inside 38 of a business establishment, and shows that each component is usually installed in the inside 38 of the business establishment.

The second antenna device is, for example, 2.4 GHz
Is an antenna device that communicates with the first antenna device 41. The third antenna device 22 is a device that communicates with a later-described fourth antenna device of a consumer. These communications are performed by a spread spectrum communication method. The spread spectrum communication system is a communication system that is resistant to noise that performs communication by dispersing frequencies. As a result, high-quality data communication is performed between the antenna devices.

The frequency converter 23 is, for example, 2.4 GH
This is a conversion device that converts z (radio frequency) into a predetermined band of a TV common listening cable. The predetermined band is a free band that does not overlap with the TV signal, for example, 900 MHz to several GHz.
Of course, other bands may be used. An empty band between TV signals may be used. A data signal is bidirectionally transmitted in the predetermined band to the coaxial cable 26, which is a TV co-listening cable. The terminal device 34 conforms to the Ethernet (registered trademark) standard IEEE8.
For example, it is a computer device that communicates with a baseband signal conforming to O.22.3, and the modem 33 is a modem device that modulates or demodulates it. In addition, the first access point device 35 is an LA based on IEEE 802.11b.
N and a plurality of wireless terminal devices 36.

The customer 50 is, for example, a private residence and includes a TV antenna device 53, a coaxial cable 55 as a TV cable, a distributor 56, and a plurality of TV devices (not shown). Usually, a TV signal is received by this TV receiving system. In the present embodiment, a fourth antenna device 51, a frequency conversion device 52,
A multiplexer 54, a modulator / demodulator 57a, a terminal device 57b, a third access point device 58, and a wireless terminal device 59 are provided. The specifications of the third access point device 58 are the first
It is the same as the access point device 35.

The fourth antenna device 51 is, for example, 2.4G
The antenna device communicates with the third antenna device 22 of the business establishment 30 in Hz. The frequency conversion device 52 includes, for example, 2.
This is a conversion device for converting 4 GHz (radio frequency) into a predetermined band of a TV cable. The meaning of the predetermined band is the same as that described in the business establishment. A data signal is bidirectionally transmitted to the TV cable 55 in the predetermined band. The terminal device 57b has the same specifications as the terminal device 34 described in the business establishment 30, and the modem 57a is the same as the modem 33.
It is the same specification as.

Hereinafter, the function of each component will be described according to the flow of signals. The signal flow will be described separately for a downlink signal from the central office 40 to each terminal device and a reverse signal for each terminal device. (Downlink signal) For example, in the case of a downlink signal, that is, the central unit 4
2 transmits data to, for example, the terminal device 34 of the business office 30 or the wireless terminal device 36, for example, 2.4 GHz
The data is transmitted from the first antenna device 41 using the band. Specifically, the transmission data is modulated by the spread spectrum modulation method or the orthogonal frequency multiplex modulation method and transmitted by radio. The signal transmitted by radio is received by the second antenna device 21 of each office 30 and is converted by the frequency conversion device 23 into a predetermined band. For example, the band of the above-mentioned modulation method is converted into a frequency up to the upper limit frequency of the coaxial cable 26, for example, 900 MHz to several GHz, and transmitted to the coaxial cable 26 via the multiplexer 25 as a predetermined band signal.
The predetermined band signal transmitted to the coaxial cable 26 is demodulated by the modem 33 of the terminal device 34. Thereby, the data from the central device 41 is received by the terminal device 34.

The predetermined band signal is transmitted to the first access point device 35 at the same time. The first access point device 35 is installed in the coaxial cable 2 in the business office 30.
This means that 6 is wirelessly extended and distributed. The first access point device 35 reversely converts the frequency of the received predetermined band signal into, for example, a 2.4 GHz band and transmits the signal to the target wireless terminal device 36. For example, the wireless terminal device 36 receives the signal if the addresses match. That is,
Data is transmitted from the central device 41 to the wireless terminal device 36.

Further, the predetermined band signal in the downstream direction is simultaneously amplified without frequency conversion by the frequency conversion device 23, for example, and amplified from the third antenna device 22 to a nearby customer 50.
To the fourth antenna device 51. The fourth antenna device 51 receives a signal from the third antenna device 22,
For example, the received signal in the 2.4 GHz band is converted by a frequency converter 52 into a carrier of a predetermined band. Then, the predetermined band signal is transmitted to the TV cable 55,
The terminal device 57b connected thereto receives the signal via the modem 57a, and the wireless terminal device 59 receives the signal via the third access point device 58. Thereby, the data signal from the central device 42 is received by the customer 50.

(Uplink signal) On the contrary, an uplink signal from each terminal device is transmitted as follows. For example, when transmitting data from the terminal device 34 of the business office 30, the modem 3
3 modulates a carrier in a predetermined band with data and transmits the modulated data to the coaxial cable 26. In the case of wireless transmission from the wireless terminal device 36, the first access point device 35 converts the signal into a predetermined band signal and transmits the signal to the coaxial cable 26.
The predetermined band signal transmitted to the coaxial cable 26 is input to the frequency converter 23 following the distributor 31 and the multiplexer 25 in reverse. The frequency converter 23 reversely converts the predetermined band signal into, for example, a 2.4 GHz band. Then, the signal is transmitted from the second antenna device 21 to the first antenna device 41 by radio in the frequency band of 2.4 GHz. Alternatively, the signal is transmitted from the third antenna device to the fourth antenna device at the same frequency.
As a result, from the business establishment 30 to the central office 40 or the customer 50
The data is sent to.

The upstream signal from the customer 50 is transmitted as follows. For example, the terminal device 57b is
A carrier wave of a predetermined band is modulated with the data using 7a to be converted into a predetermined band signal and transmitted to the TV cable 55. or,
When transmitting wirelessly from the wireless terminal device 59, the third access point device 58 converts the signal into a predetermined band signal and transmits the signal to the coaxial cable 55. The transmitted predetermined band signal traces the distributor 56 and the multiplexer 54 in reverse, and is input to the frequency converter 52. The frequency converter 52 converts the frequency to, for example, a 2.4 GHz band. Then, the fourth antenna device 51 communicates with the third radio using the frequency band of 2.4 GHz.
The signal is transmitted to the antenna device 22.

Then, the frequency converter 23 of the business office 30
If the communication destination of the received signal is another office, the first antenna device 41 of the central office 40 is transmitted from the second antenna device 21
Send to As a result, the customers 5 near the business establishment 30
0 can be transmitted to the terminal device of the business office 30 in another area. Also, the communication destination of the received signal is
If it is a terminal device in the above, it is transmitted to the subsequent frequency conversion device 23. The data from the terminal device of the customer 50 is transmitted in this manner.

As described above, if the network system of this embodiment is adopted, that is, the first antenna device 41 in the central office 40, the second antenna device 21, the third antenna device 22, and If the consumer 50 is provided with the fourth antenna device 51 and uses the coaxial cable 26 and the TV cable 55 which are conventional TV listening cables, it is not necessary to lay a new transmission line or drop-in line in the city. A network system can be built. That is, a LAN and a WAN that are excellent in cost efficiency can be formed. In this embodiment, the access point devices 35 and 58 are provided on the coaxial cable 26 and the TV cable 55 which are TV co-listening cables.
The wireless terminal devices 36 and 59 can be used. Therefore, the LAN can be a LAN having excellent flexibility. Further, the above configuration is configured to separate the TV signal band and the data signal band. Therefore, data communication can be performed without affecting the conventional TV signal. Both data communication and TV reception can be simultaneously enabled.

(Second Embodiment) FIG. 2 shows a second embodiment of the network system of the present invention. The figure is a configuration block diagram on the business site side. Parts having the same functions as those in FIG. 1 described in the first embodiment are denoted by the same reference numerals.
The feature of this system is that an access point extension circuit 60 is provided at point A in the system configuration diagram (FIG. 1) of the first embodiment. As a result, the number of communicable wireless terminal devices is increased to form a large-scale wireless LAN. Another advantage is that the access point devices to be transmitted and received are sequentially switched so that the wireless terminal device can move significantly during communication.
This makes the LAN more flexible.

The access point extension circuit 60 used in this embodiment includes a duplexer 61 and a second access point device 6.
2, 64, a hub 63 as a line concentrator, an amplifier 69 for amplifying a TV signal, and a multiplexer 65. Here, the second access point device 62 is a three-way input / output device. For example, a data signal (RF signal) input in a predetermined band from the upstream (demultiplexer 61) is converted into a baseband signal and transmitted to the downstream (hub 63) via, for example, a twisted pair wire 63a, and the other is transmitted to the downstream (hub 63). For example, 2.4GH
The signal is transmitted from the small antenna 62a by radio of z. vice versa,
One of the signals input as the baseband signals from the downstream is transmitted upstream with a predetermined band signal, and the other is, for example, 2.4G
The radio wave is transmitted to the outside from the small antenna 62a by radio of Hz. Further, for example, one of the signals input wirelessly at 2.4 GHz is converted into a baseband signal and transmitted downstream, and the other is transmitted upstream with a modulated signal of a predetermined band. Such a three-way input / output device.

In this configuration, a predetermined band signal (data signal)
Is distributed to more wireless terminal devices. That is, a plurality of bypass circuits 66 are provided at the point A in FIG. 1, that is, at the input of the co-listening system, in which only a predetermined band signal is branched into a plurality of signals, and the second access point device 62 is provided in each of the bypass circuits 66. Configuration. In this case, the plurality of bypass circuits 66 are formed between the duplexer 61 and the hub 63.

For example, when a data signal is transmitted upstream from the office interior 38, if the communication destination is the wireless terminal device 37 within the office 30, the data signal does not trace back to the upstream second antenna device 21. The data is transmitted to the target wireless terminal device 37 by the hub 63 and the second access point device 62. Conversely, when the second antenna device 21 or the third antenna device 22 receives the signal, the received signal is transmitted to the target terminal device 37 by the plurality of second access point devices 62.
Send to Since the plurality of second access point devices 62 are installed inside the office 38, the communication area can be easily expanded.

The plurality of second access point devices 62
If the wireless terminal device 37 is provided in different places of the business office 30 and is sequentially switched, the wireless terminal device 37 can move even during communication. That is, since the second access point device 62 is sequentially switched, communication is always possible. A so-called roaming function can be provided. Therefore,
Mobile communication can be enabled. Thus, the second
If the access point devices 62 are provided in parallel and switched by the hub 63, the communication area of the wireless terminal device can be further expanded. In addition, mobile communication of the wireless terminal device can be performed, and a network system having excellent convenience and flexibility can be provided.

(Third Embodiment) FIG. 3 shows a third embodiment of the network system of the present invention. The figure is a configuration block diagram. The network system of the present embodiment is a CATV
Station 70, central unit 42, optical fiber cable 71, photoelectric converter 72 provided at the end thereof, photoelectric converter 72
It comprises a first antenna device 41 installed above, each business office 30 and a customer 50. In the first embodiment and the second embodiment, the first antenna device 41 is provided in the central office 40, but in the present embodiment, the first antenna device 41 is provided at the tip of the optical fiber cable 71 laid in the city. Is the feature.

With such a configuration, the CATV station 70
The data signal from the central device 42 is sent to the photoelectric converter 72 as an optical signal, and the optical signal is converted into an electric signal. The data signal converted into the electric signal is wirelessly transmitted to each office 30 by the first antenna device 41. Conversely, each office 30
Is received by the first antenna device 41 at the tip of the optical fiber 71,
Is converted into an optical signal and transmitted to the central device 42 via the optical fiber 71. That is, the communication distance can be easily increased without increasing the output of the first antenna device 41. In addition, a lead-in wire from the optical fiber 71 is connected to each office 30
There is no need to lay down. Therefore, the network system is excellent in convenience and cost-effective. or,
The optical fiber 71 can transmit data over a long distance with good quality. Therefore, high quality data communication can be provided to the business office 30 and the customer 50 at the optical fiber tip. That is, it is possible to provide the customer 50 with a high quality WAN.

Further, in this embodiment, the second antenna device 21 of each office 30 has an address, and when the addresses match, transmits the received signal to the subsequent frequency converter 23,
That is, the signal is transmitted to the TV co-listening cable 26 and / or the third antenna device 22, and if not coincident, is amplified and transmitted to the second antenna device 21 of another office 30. For example, if the addresses match, there is no need to send the data signal to another business establishment 30. Conversely, when the addresses do not match, it is not necessary to transmit the addresses to the terminal devices 34 and 57b in the business office 30. Thus, a power-saving network system can be provided. The above configuration is a configuration in which the second antenna device 21 is a kind of repeater. That is, when the addresses do not match, the data signal is sequentially transferred to the adjacent business office 30. For example, if the distance between offices is several kilometers, the communication area can be sequentially expanded. That is, it is possible to construct a network system that provides communication services to more customers.

(Modifications) Although one embodiment of the present invention has been described, various other modifications are conceivable. For example, in the first embodiment, the coaxial cable 26 is provided with the first access point device 35 for connecting the wireless terminal device 36 and the wired LAN, but instead of this, the second access point device 35 shown in the second embodiment is used.
An access point device 62 may be provided. The second access point device 62 is capable of inputting / outputting a baseband signal in addition to inputting / outputting a wireless input / output and an RF signal which is a predetermined band signal. As a result, terminal devices of various communication systems can be connected to the subsequent stage. Therefore, a network system that can support various communication schemes can be provided.

In the first to third embodiments, the frequency converters 23 and 52 operate, for example, in the 2.4 GHz band at 900 MHz.
Although the description has been given of the example of conversion into the z band, the frequency conversion device 23 may be non-conversion. If the transmission distance of the coaxial cable 26 and the TV cable 55 is a short distance and the attenuation due to the transmission distance is not significant, the band may be in the 2.4 GHz band. That is, the first
The frequency conversion device 23 and the frequency conversion device 52 may be simple buffer devices having the same input and output frequencies. Further, the frequency may be lower than the 900 MHz band. That is, it may be an empty channel of the TV signal.

In the second embodiment, all of the second access point devices 62 provided in the bypass circuit 66 are connected to the hub 63 at the subsequent stage. However, not all of them need to be connected. Since the second access point device 62 can convert a predetermined band signal into a baseband signal, the second access point device 62 may directly include the terminal device 39 suitable for the communication system (FIG. 4). This terminal device 39 is connected to the second access point device 6 thereon.
2 can communicate with other terminal devices.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a network system according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a co-listening system according to a second embodiment of the present invention.

FIG. 3 is a configuration block diagram of a network system using an optical fiber according to a third embodiment.

FIG. 4 is a block diagram showing a configuration of a co-listening system according to a modification of the second embodiment of the present invention.

FIG. 5 is a system configuration diagram of a CATV network using a conventional co-listening system.

[Explanation of symbols]

 21 second antenna device 22 third antenna device 23, 52 frequency conversion device 24, 53 TV antenna device 25, 54 multiplexer 26 coaxial cable 30 business office 31, 56 distributor 32 TV Devices 33, 57a Modulators 34, 57b Terminal devices 35, 58 First access point devices 36, 59 Wireless terminal devices 41 First antenna device 42 Central device 50 Customer 51 Fourth antenna device 55 ... TV cable 60 ... Access point extension circuit

Claims (13)

[Claims] 1. A network system comprising a central device and a plurality of terminal devices, wherein the network device uses a TV co-listening cable at each business office, wherein the central device is provided with a first antenna device, A second antenna device that communicates with the central device, and a frequency conversion device that converts an input / output signal of the second antenna device into a predetermined band signal and inputs / outputs the signal to / from the TV listening cable at each of the offices. A network system, wherein the terminal device at each of the offices communicates using the TV co-listening cable and / or the second antenna device. 2. The network system according to claim 1, wherein the first antenna device is connected to a tip of an optical fiber extending from the central device via a photoelectric converter. 3. The second antenna device has an address,
2. The method according to claim 1, wherein when the data and address of the received signal match, the received signal is sent to the subsequent frequency converter, and when not matched, the signal is amplified and sent to another second antenna device. Item 3. The network system according to Item 2. 4. The network system according to claim 1, wherein the frequency conversion device has a third antenna device for transmitting and receiving to and from a terminal device in a nearby area. 5. The frequency conversion apparatus further comprises a TV antenna apparatus at a subsequent stage, and multiplexes the received TV signal with the predetermined band signal converted by the frequency conversion apparatus, and
The network system according to any one of claims 1 to 4, further comprising: a multiplexer that transmits the signal to the common listening cable. 6. In any part of the TV common cable,
The network system according to any one of claims 1 to 5, further comprising a first access point device for connecting a wired LAN and a wireless terminal device. 7. In any part of the TV common cable,
7. The apparatus according to claim 1, further comprising a second access point device for mutually converting the predetermined band signal into a wireless signal and / or a baseband signal conforming to Ethernet (registered trademark) specifications. The network system according to the section. 8. The apparatus according to claim 5, wherein a plurality of bypass circuits for bypassing the predetermined band signal are provided at a subsequent stage of the multiplexer, and the second access point device is provided in the plurality of bypass circuits. The described network system. 9. A concentrator for concentrating the baseband input / output of the second access point device after the plurality of second access point devices provided in the plurality of bypass circuits; The network system according to claim 8, further comprising: another second access point device that converts the baseband signal condensed into the predetermined band signal. 10. The consumer under the third antenna device,
A TV antenna system that includes a TV antenna device and a TV audio cable, a fourth antenna device that communicates with the third antenna device, a frequency converter that converts input and output of the fourth antenna device into a predetermined band signal, The network according to any one of claims 4 to 9, further comprising: a multiplexer for multiplexing the TV signal and the predetermined band signal and transmitting the multiplexed signal to the TV common cable. system. 11. The network according to claim 10, wherein a third access point device having the same specification as the first or second access point device is provided at any point of the TV common listening cable. system. 12. The communication system according to claim 4, wherein a communication system between said third antenna device and said fourth antenna device is a communication system using a modulation system having high noise resistance.
The network system according to any one of claims 1 to 7. 13. The communication system according to claim 1, wherein a communication system between said first antenna device and said second antenna device is a communication system using a modulation system having high noise resistance.
3. The network system according to any one of 2.