JP2001177852A - Catv two-way communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CATV two-way communication system where a CATV center and subscriber terminals are interconnected via a 2-way transmission channel and the operation/maintenance in common to a status monitor system and a cable modem system are totally attained for each transmission channel. SOLUTION: A controller is provided in a transmission channel 10 and the CATV center 1 and subscriber terminals 4, 5 make communication with a prescribed protocol. Then the center 1 periodically monitors communication quality of the transmission channel 10 with the controller and applies gate closing control of the controller so that this communication quality exceeds a threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV two-way communication device, and more particularly to a CA in which a CATV (cable television) center and a subscriber terminal device are connected via a two-way transmission line.
The present invention relates to a two-way TV communication device.

[0002] CATV bidirectional transmission path (for example, 10 to 50 MHz
In a communication service that digitally modulates a part of the band (downward 70 to 770 MHz), for example, an Internet connection service using a cable modem, a CATV bidirectional transmission path is used as a data communication path. This CATV bidirectional transmission line
Since it has a star-type or tree-type network configuration centered on the center, there is a drawback that noise due to failure of the CATV bidirectional transmission line itself and noise from CATV subscribers' homes concentrate on the CATV center as upstream noise. .

[0003] In communication services, such noise causes an increase in data errors and a resulting retransmission request, thereby lowering the communication speed and deteriorating the communication quality. It is necessary to remove the cause of the deterioration.

[0004]

2. Description of the Related Art FIG. 10 shows a conventionally known CATV two-way communication device. In the figure, reference numeral 1 denotes a CATV center, which is connected to the Internet 2 in order to realize an Internet connection service using a cable modem. Further, the CATV center 1 is connected to main-line amplifiers 31 and 32 (which may be collectively referred to by reference numeral "3") via a bidirectional transmission line 10. The main amplifier 3 is further connected to a cable modem 4 and a subscriber personal computer 5 constituting a subscriber terminal device via a bidirectional transmission line 10.

[0005] In the CATV center 1, when a TCP / IP network is operated using an application / management server 11 required as an Internet connection provider and a bidirectional transmission path 10 as a predetermined protocol, the state of the network is changed. Console device for monitoring
SNMP (Simple Network Management Protocol) Manager
12 and a cable modem management device 13, which is a console device operated by an operator to control and operate the cable modem termination device 15.

The server 11, the SNMP manager 12, and the cable modem management device 13 are connected to the Internet 2 via a LAN (local area network) 20 and a router 16, and are connected via a LAN 20 and a cable modem termination device 15 to a head. Connected to end 14.

The head end 14 is further connected to a CATV center.
In FIG. 1, a status monitor device (control / monitoring device) 22 is connected via a status monitor modem 21 to mix / separate signals with respect to the bidirectional transmission line 10. Such a CATV two-way communication device is composed of a cable modem system and a status monitor system.

[0008] Among them, the cable modem system is a CA.
A cable modem termination device 15 in the TV center 1, a server 11, an SNMP manager 12,
And a cable modem management device 13 and a cable modem 4 and a subscriber personal computer 5 in the subscriber's house.

Then, the SNMP manager 12 monitors and controls the cable modem 4 at the subscriber's house by an SNMP monitoring signal, which is a network management protocol of TCP / IP, so that the subscriber's personal computer 5 and the server 11 within the CATV center 1 can be monitored. Data communication is performed with the Internet 2 using an IP packet signal. Also, cable modem management device
13 is the operation / operation of the cable modem 4 by the control / monitoring signal.
Performs maintenance and management.

On the other hand, the status monitor system uses a CATV
It comprises a status monitor modem 21 and a status monitor device 22 in the center 1 and a status monitor unit built in the trunk amplifier 3. Then, the status monitor device 22 displays the occurrence of noise contamination from the main amplifier 3 on the console by using a control / monitoring signal independent of the above-mentioned signals (1) to (6), and based on the display status, the main amplifier 3 The operator manually operates the up-gate closing control of the status monitor unit built in the system to block the inflow of noise into the CATV center 1.

FIG. 11 shows an example of a conventional configuration of the main line amplifier 3, in which "input" and "output" indicate input / output terminals on the main line side of the main line amplifier, and "branch 1" and "branch 2". , "Branch
“3” and “branch 4” indicate input / output terminals of the branch system, respectively. The status monitor unit is "STM"
This is an optional unit that inputs and outputs signals from the "RF" terminal branched from the CATV trunk system.

In this status monitor unit STM,
Signals are transmitted / received to / from the AGC circuit and the gate switch GS in the main line amplifier 3, and monitoring and control of transmission / reception level (AGC) and up gate control (GS) of the CATV main line / branch side are performed. That is, when noise is mixed in from the trunk line and the branch input terminal and normal communication cannot be maintained, the reception system of the uplink signal can be shut off by closing the gate switch GS.

In FIG. 1, "H" indicates a high-pass filter in the downstream signal direction, "L" indicates a low-pass filter in the upstream signal direction, and "BPF" indicates a band-pass filter. Further, "ATT / EQ" indicates an attenuator / equalizer.

[0014]

As described above, the conventional CATV
In the two-way communication device, since the status monitor system and the cable modem system have independent configurations, there are the following problems.

(1) Since a separate modem and console device are required for each system, the hardware scale in the CATV center is increased. (2) If the status monitor system detects a communication error due to noise level deterioration and simply shuts off the main line amplifier by gate closing control, normal communication services in a cable modem system sharing a bidirectional transmission path will be affected. I will come out.

(3) The deterioration of the communication quality of one system (such as a decrease in the communication speed) cannot be analyzed by the system alone, and the analysis by the other system is also required. On the other hand, JP-A-6-24
In the bidirectional amplifier shown in No. 5212 (corresponding to the above-mentioned main line amplifier), a method is adopted in which when the upstream signal continues for a predetermined time or more, the upstream signal is determined to be noise and the upstream signal is cut off. However, since the center control cannot be executed, there is a problem that comprehensive gate control including each trunk line system cannot be realized and no operator can intervene.

Accordingly, the present invention provides a CATV two-way communication device in which a CATV center and a subscriber terminal device are connected via a two-way transmission line, wherein the operation / maintenance common to the status monitor system and the cable modem system is performed by each transmission. The purpose is to be able to perform comprehensively on roads.

[0018]

In order to achieve the above object, a CATV two-way communication device according to the present invention includes a control device provided in a two-way transmission line, and a center and a subscriber terminal device are provided with a predetermined protocol. And the center periodically monitors the communication quality of the transmission path with the control device, and performs gate closing control of the control device so that the communication quality is equal to or higher than a threshold value. I have.

That is, in the present invention, the CATV center and the subscriber terminal device are provided with a predetermined protocol (for example, TCP / IP).
When communication is performed by the CATV center, the CATV center periodically monitors the communication quality (for example, data transfer speed by ftp) with the control device provided in the bidirectional transmission path. If it is determined that the communication quality has deteriorated below the threshold value, the control unit closes the gate of the control device so as to exceed the threshold value.

As described above, the CATV center and the subscriber terminal device can communicate with the same protocol, and the communication quality monitored on the side of the CATV center is equivalent to the communication quality surfaced on the subscriber terminal device. Can be The above control device may be built in a main amplifier provided in a bidirectional transmission line.

Further, the CATV center can sequentially perform the gate closing control from the trunk amplifier on the far end side of the bidirectional transmission line, thereby making it possible to cut off communication with a minimum number of subscriber terminal devices. Becomes Alternatively, the CATV center can minimize the influence on the subscriber terminal device in the least number of ways by preferentially performing gate closing control on a trunk amplifier having no subscriber terminal device under its control.

Furthermore, the gate closing control may be performed on the main line amplifier having a small number of subscriber terminal devices under its control from the beginning. Further, when there are a plurality of trunk systems and a certain trunk system has only a single trunk amplifier or has no trunk amplifier at all, if this trunk amplifier is preferentially gate-closed, it is similarly joined. It is possible to minimize the influence on the user terminal device.

Further, according to the present invention, when it is determined whether or not the communication quality has been restored, the gate is opened at regular intervals for the trunk amplifier which has been controlled to close the gate, and the communication quality at this time is monitored. If the communication quality has been recovered, it can be determined that the communication has been recovered.

The above-mentioned center includes a cable modem terminator connected to the transmission line via a headend, a cable modem management device for controlling and operating the terminator by an operator, and each of the cable modem management devices connected to the terminator. It can be configured with an SNMP manager to monitor the mains amplifier.

In the present invention, if a console display of the quality of goods is displayed on the SNMP manager provided at the CATV center, the operator of the SNMP manager can manually perform the gate closing control on the corresponding control device. It is possible to do. As described above, according to the present invention, it is possible to integrate and operate / maintain the data monitor system and the cable modem system, and it is possible to detect a communication abnormality due to the deterioration of the noise level in both systems. Recovery can also be done quickly and easily.

[0026]

FIG. 1 shows an embodiment of the configuration of a CATV center two-way communication apparatus according to the present invention. This embodiment differs from the conventional example shown in FIG. 11 in that the status monitor modem 21 and the status monitor device 22 constituting the status monitor system in the CATV center 1 are removed.

That is, as a device necessary for providing an Internet connection service using a CATV bidirectional transmission line, a cable modem terminating device 15 is installed in the CATV center 1.
It is assumed that a cable modem management apparatus 13 and an SNMP manager 12 are installed, and a CATV system and a company in which a cable modem 4 and a subscriber personal computer 5 are already installed and operated in a subscriber's house.

Here, the cable modem terminating device 15 is a CA
This is a control device for realizing bidirectional communication according to the TCP / IP procedure on the TV bidirectional transmission line 10, and is a control operation device of the cable modem 4 installed at the subscriber's house and connecting the subscriber's personal computer 5. The cable modem management device 13 is a console device for setting and managing the cable modem 4 and various control / operation / maintenance data. SNMP Manager 12
LA using SNMP, a procedure for managing devices with TCP / IP
N / server device management device.

The server 11 is an application / management server required as an Internet connection provider. The trunk amplifier 3 is not a conventional status monitor system, but is a cable modem termination device 15, a cable modem management device 13,
And a “control device” managed by the SNMP manager 12. Therefore, this control device also communicates with the cable modem 4 using the same TCP / IP.

That is, the main amplifier 3 differs from the conventional example shown in FIG. 12 in that a control device 6 having a configuration as shown in FIG. 2 is used instead of the status monitor modem STM. In the embodiment of FIG. 2, the controller connects a cable modem 61 to an RF input terminal, connects the cable modem 61 to a control processor 62, and connects a program ROM 63 and a RAM 64 to the control processor 62. It is also connected to the I / O control unit 65.

The cable modem 61 is controlled and operated by the cable modem management device 13 installed in the CATV center 1, and has the same system and the same functions as the cable modem generally installed in the subscriber's house. I have. Further, the control processor 62 controls and executes TCP / IP communication via the cable modem 61, and also controls the status monitor unit.
6 is a processor for controlling the whole, and controls a program ROM 63 and a RAM 64 for implementing an execution program such as a TCP / IP implementation or an ftp application.

The status monitor unit ST shown in FIG.
The control and the like for the AGC circuit and the gate switch GS executed in M are monitored and controlled via the I / O control unit 65. Here, an example (1) of the system construction procedure of the embodiment shown in FIG. 1 will be described with reference to FIG.

First, a procedure example (1) for constructing the entire infrastructure of the embodiment of FIG. 1 will be described.
4. The optical coaxial two-way transmission line 10 and the trunk amplifier 3 are constructed (step S1). At this point, the television broadcasting service can be started. Next, cable modem termination device 1
5, cable modem management device 13, SNMP manager 12,
Then, the server 11 is constructed (step S2).

Further, the control device 6 is incorporated in the main line amplifier 3 (step S3). Next, the cable modem management device 13 and
Set data in the SNMP manager 12 (Step S
Four). As the data setting, there is a threshold value of a data transfer speed, which will be described later.

Then, the operation of the control device 6 is started (step S5). In example (2) of the schematic procedure of operation, first, as a center operation task, the status display of the control device 6 is displayed by a cable using an SNMP monitoring signal and a control / monitoring signal (IP packet signal) based on the TCP / IP communication shown in FIG. Performed by the modem management device 13 and the SNMP manager 12 (step
Along with S11), the control device is operated by TCP / IP (gate control, status monitoring / control, etc.) (step S12).

Further, as a subscriber operation service, the cable modem 4 is installed in the house together with the center operation service (step S13), and TCP / IP communication is executed by the subscriber (step S14), and the cable modem management device 13 and SNMP
The center operation by the manager 12 is started (step S15).

FIG. 4 shows an embodiment when the CATV two-way communication apparatus according to the present invention shown in FIG. 1 is operated (center operation operation in FIG. 3). In this embodiment, the I shown in FIG.
An ftp transfer packet is used as a control / monitoring signal as a P packet signal.

That is, as a method in which the control device 6 incorporated in the trunk amplifier 3 monitors the communication quality of its own trunk system, regular communication by TCP / IP is assumed, and the TCP / IP The application is used to periodically perform data transfer with the cable modem management device 13 installed in the CATV center 1 using an ftp (file transfer protocol) transfer packet.

The operation of the embodiment shown in FIG. 4 will be described below with reference to the flowcharts shown in FIGS. First,
The cable modem management device 13 ftps each trunk amplifier 3
To collect and accumulate transfer speed data (step
S21). The operating state at this time is schematically shown in FIG.

That is, as in this example, the head end 14
Are connected to the trunk system A, and the trunk amplifiers 31 to 34 are connected to the trunk system A via a bidirectional transmission path. Modem termination device 15 and headend
The data transfer of ftp 1 is periodically performed to the main amplifier 31 via 14, and the data transfer of ftp 2 is also performed periodically to the main amplifier 32.

At this time, as shown in FIG.
It is assumed that normal small noise is mixed downstream of the main line amplifier (downstream of the cable modems 41 and 42) and large noise considered to be abnormal is mixed downstream of the main line amplifier 34 (downstream of the cable modem 43). The data transfer rates obtained by the ftp 1 and ftp 2 from the cable modem management device 13 for 31 and 32 will change according to these noises.

The cable modem management device 13 displays the status of such ftp data transfer speed (step S2).
2), whether to enter the operator operation mode is selected (step S23). When entering the operator operation mode, that is, the manual operation mode, the cable modem management device
Control is performed on the console screen 13 to close the gate of the main amplifier considered to be abnormal (step S24).

Referring to the graph of FIG. 8 regarding the abnormality of the ftp data transfer rate in this case, the steady-state ftp data transfer rate takes a value shown by a solid line, and is always above the threshold. When the contamination increases, an abnormal value below the threshold value is indicated as shown by the dotted line.

Now, as shown in FIG. 9, in the mains system A, small noise that can be normally generated downstream of the main amplifiers 31 and 32 is mixed, and an abnormally large noise that cannot normally be generated downstream of the main amplifier 34. If it is assumed that noise is mixed in and the main system B is assumed to be mixed with small noise that can normally occur, the noise is mixed in the upstream transmission line.
Since the C / N ratio of 10 deteriorates, the uplink communication quality of the control device 6 built in the trunk amplifier deteriorates (the communication speed decreases due to the retransmission processing performed by the error detection processing).

Since the bidirectional transmission line 10 is a radial network centered on the CATV center 1, noise mixed in the trunk system A (in the case of the gate opening (1) in the figure) is collected at the CATV center 1, and Is also mixed with the trunk system B of
This results in a worse C / N ratio.

As a result, the deterioration of the communication quality is
In addition to the control devices housed in the mains system, the control devices housed in the main system B are also limited. It is necessary to close the up gate of the main system A (when the gate is closed (2)) to prevent the transmission of noise.

In consideration of the above, the operator is required to
As shown in (1), a command is issued () from the cable modem management device 13 and the cable modem termination device receiving the command
15 gives the command execution () to the control device 6 of the main line amplifier 32 to perform the up gate closing control.

As a result, when the gate of the main amplifier 32 is opened as shown in the figure (1), when the gate is closed (2), only a small amount of normal noise is transmitted through the cable modem terminating device 15 when the gate is closed (2). This is mixed into the modem management device 13. Returning to the flowchart of FIG. 5, step S
Following 24, the cable modem management device 13 continues to monitor the ftp data transfer rate (step S25) and executes this until the operator operation mode ends (step S2).
6).

If the operator mode is not entered in step S23, that is, if the automatic control is entered, the cable modem management device 13 sets the ftp data transfer rate of each trunk amplifier collected as shown in FIG. This is compared with a threshold for each system. In this example, first, the entire data transfer rate of the trunk system A is compared with a threshold value (step S27).

As a result, when it is found that the data transfer rate is lower than the threshold value as shown in FIG. 8, that is, when it is found that the noise is large, the process proceeds to step S28 in FIG. First, it is determined whether or not a plurality of main amplifiers exist. In the example of FIG. 9, since a plurality of trunk amplifiers exist on the trunk system A, the process proceeds to step S29,
The ftp transfer speed of each trunk amplifier is sequentially checked toward the far end of the trunk system A.

At this time, it is checked whether or not there is a subscriber terminal device under the control of each main line amplifier based on the system construction data set in advance in the cable modem management device 13 (step S30), and the subscriber terminal device is under the control. In this case, the numbers are compared with each other (steps S31 and S32).

As a result, the gates are closed by sequentially controlling the main amplifier control device having a smaller number of subscriber terminals under its control (step S33). This is because the effect on the subscriber can be minimized by closing the gate from the main line amplifier having a small number of subscriber terminal devices.

As a result, it is again checked whether or not the data transfer rate has fallen below the threshold (step S34). If the data transfer rate still falls below the threshold, the gate of the trunk amplifier having a large number of subscriber terminals is gradually closed. Therefore, it is checked whether or not all the gates are closed (step S35). If the data transfer speed is not restored even when all the gates are closed, the same check is performed for another trunk system B. Perform (Step S36).

On the other hand, if it is found in step S30 that there is no subscriber terminal device under the control, step S3
Proceed to 7 to close the gate of the amplifier without the subscriber terminal. This is because noise can enter the transmission line 10 even when the subscriber terminal device is not connected.

Thereafter, the data transfer rate is compared with the threshold value again.
Returning to S31, the same steps S31 to S36 as described above are executed, but if not, the process proceeds to step S39. In step S39, the gate is opened at regular time intervals, thereby determining whether or not the data transfer rate has been restored (step S40). If it is found that the data transfer rate has been restored, the gate is completely opened (step S41).

On the other hand, if it is determined in step S28 that there is no trunk amplifier in trunk system A, it is determined that there is only a single trunk amplifier or that there is no trunk amplifier, and the gate is closed (step S28). S42), Steps S43 to S46 are executed in the same manner as steps S38 to S41 described above.

In this case as well, if it is found in step S43 that the data transfer rate has not recovered, the process proceeds to step S36. Note that, depending on the trunk amplifier equipped with the control device, there may not be an up gate, and in such a case, the up gate of the subsequent trunk amplifier may be operated according to the judgment of the cable modem management device 13.

In addition, these determinations can be made to recover in a better direction in the entire system by grasping the overall condition of the CATV bidirectional transmission line 10, such as by using the same data as other trunk systems (subscription). Priority is given to rescue). These judgments and control means are SNP Manager 1
2 or the server 11 may be provided.

In the above embodiment, the control device is installed in the main amplifier. However, the present invention is not limited to this. For example, the control device may be installed in a splitter, a tap-off, a security device, a home booster, or the like. Furthermore, TCP / IP is used as a protocol for determining communication quality deterioration.
, And ftp was assumed as the application, but other TCP / IP applications or TCP / IP
Similar effects can be obtained by using a protocol other than the above.

[0060]

As described above, according to the CATV two-way communication apparatus according to the present invention, the control device is provided in the transmission path, and the CA
The TV center communicates with the subscriber terminal device according to a predetermined protocol, and the center periodically monitors the communication quality of the transmission line with the control device, and controls the control device so that the communication quality exceeds a threshold value. , The status monitor system and the cable monitor system can be unified and operated / maintained, and communication errors caused by noise level deterioration in both systems can be detected and controlled. Can be eliminated.

Further, since data communication control is performed between the center and the control device according to a predetermined protocol, a communication error which is a problem in the control device can be detected as the same communication error in the subscriber terminal device. Further, since the gate of the control device is controlled to be closed to the minimum necessary, it is possible to eliminate the influence on the communication service on the normal transmission path.

Further, if a standard system configuration and protocol are used, it is possible to obtain an effect that cost reduction and uniform operation can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment on the configuration of a two-way communication device according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a control device built in the main line amplifier used in the CATV two-way communication device according to the present invention.

FIG. 3 is a flowchart showing an example of a procedure for constructing a system of the CATV two-way communication device according to the present invention shown in FIG. 1;

FIG. 4 is a diagram schematically showing an operation example of the CATV two-way communication device according to the present invention shown in FIG. 1;

FIG. 5 is a flowchart showing an operation example (1) of the embodiment of the present invention shown in FIG. 4;

FIG. 6 is a flowchart showing an operation example (part 2) of the embodiment of the present invention shown in FIG. 4;

FIG. 7 is a diagram illustrating a specific operation of a noise mixing source in the CATV two-way communication device according to the present invention.

FIG. 8 is a graph showing a relationship between a communication quality (ftp data transfer speed) and a threshold value in the CATV two-way communication device according to the present invention.

FIG. 9 is a diagram for explaining manual control and automatic control in the CATV two-way communication device according to the present invention.

FIG. 10 is a diagram showing a configuration example of a conventional CATV two-way communication device.

FIG. 11 is a block diagram showing a configuration example of a conventional trunk amplifier.

[Explanation of symbols]

 1 CATV center 2 Internet 3,31-38 Trunk amplifier 4,41-46 Cable modem 5 Subscriber PC 6 Control device 11 Server 12 SNMP manager 13 Cable modem management device 14 Headend 15 Cable modem termination device 16 Router 61 Cable modem 62 Control processor 63 Program POM 64 RAM 65 I / O control unit 10 Bidirectional transmission line 20 LAN The same reference numerals in the figures indicate the same or equivalent.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C061 BB03 BB13 BB18 CC03 5C064 BA01 BB05 BC10 BC12 BD16 5K030 GA14 GA17 HC01 HD03 JA09 JA10 LD07 LE05 MB01 5K032 AA06 BA07 DA03 DA08 DB14 DB28

Claims (11)

[Claims] A CATV bidirectional communication device in which a CATV center and a subscriber terminal device are connected via a bidirectional transmission line, wherein a control device is provided in the transmission line, and the center and the terminal device are connected to a predetermined terminal. Communication with the protocol, the center periodically monitors the communication quality of the transmission path with the control device, and performs gate closing control of the control device so that the communication quality becomes equal to or higher than a threshold value. Made
CATV two-way communication device. 2. The CATV two-way communication device according to claim 1, wherein said protocol is TPC / IP. 3. The CATV two-way communication apparatus according to claim 2, wherein a data transfer rate measurement using a data communication procedure including ftp is used as the communication quality. 4. The CATV two-way communication device according to claim 1, wherein the control device is incorporated in a main line amplifier provided in the transmission line. 5. The CATV two-way communication apparatus according to claim 4, wherein said center performs gate closing control sequentially from a trunk amplifier at a far end of said transmission path. 6. The CATV two-way communication apparatus according to claim 5, wherein said center performs gate closing control sequentially from said trunk line amplifiers having no subscriber terminal devices under their control. 7. The CATV two-way communication device according to claim 5, wherein the center performs gate closing control sequentially from the main line amplifier having a smaller number of subscriber terminal devices under its control. 8. The two-way CATV communication system according to claim 5, wherein said center preferentially closes the gate of said trunk amplifier when there is at most a single trunk amplifier in the same trunk system. apparatus. 9. The communication system according to claim 4, wherein the center monitors the communication quality by opening the gate of the trunk-line amplifier whose gate is controlled to be closed at regular time intervals, and monitors whether the communication quality has been restored. CATV two-way communication device, characterized in that: 10. The cable modem according to claim 4, wherein the center is a cable modem terminator connected to the transmission line via a headend, and a cable modem controlled and operated by an operator of the terminator. A CATV two-way communication device, comprising: a management device; and an SNMP manager connected to the terminating device for monitoring each trunk amplifier. 11. The CATV two-way communication apparatus according to claim 10, wherein the center manually controls the gate closing control of the main line amplifier by an operator monitoring the cable modem device.