JPH0815273B2 - Intelligent headend and its communication method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intelligent headend and a communication method therefor, and more particularly to fully symmetric bidirectional N-to-N communication, dynamic optimal allocation of channels, and network topology-free network configuration control. It concerns possible headends and their communication methods.

2. Description of the Related Art A local area network (hereinafter, LAN) in which a host computer and a terminal are connected via an optical fiber or a coaxial cable is widely used as a practical communication system. LAN communication methods include a baseband method that transmits transmission data without modulation and a method that modulates and transmits a carrier wave with transmission data.In the latter method, multiple signals are assigned to different bands and are simultaneously transmitted. Can be sent.

Conventionally, in a broadband network (including LAN) using a coaxial cable or an optical fiber cable as a transmission path, there is no known one in which a head end for controlling the network has an intelligent function. For example, the conventional headend has a simple configuration and functions, for example, the channels used by the transmitting side device and the receiving side device provided in the headend form a pair, and there is no need to control the headend from the outside. Further, each headend was able to perform communication of N: M (a positive integer for both the number N of transmitting terminals and the number M of receiving terminals, N> M), and broadcast communication was also possible. However, in order to perform N: N communication, that is, communication between corresponding two headends, it was necessary for the device side to have the capability of transmitting and receiving all channels. Furthermore, the conventional headend has a fixed network topology, and once designed, it is almost impossible to change.

In this way, in the conventional headend, N: N communication cannot be performed over all channels, automatic channel allocation and channel allocation optimization are not possible, and network topology changes and network expansion are not possible. Therefore, while using a medium having a transmission capability and characteristics that handle digital information and analog information in a unified manner, it has not yet been used as a communication base for a comprehensive information network.

The object of the present invention is to improve these conventional problems, in a broadband network using a coaxial cable or an optical fiber cable as a transmission path, fully symmetric bidirectional N: N communication, dynamic allocation of channels, and a network. An object is to provide an intelligent headend capable of both topology-free network configuration control and its communication method.

Configuration To achieve the above object, the intelligent headend of the present invention is connected to a wideband transmission line such as (a) a coaxial cable or an optical fiber cable, and divides the used band into a reverse channel and a forward channel, A head end 10 for performing directional communication, a means for separating a reverse channel band signal from a transmission path (bidirectional coupler 11), and a forward channel to which any channel of the separated reverse channel band is dynamically assigned Means for frequency-converting to a band channel (frequency converter 14) and means for sending out the signal whose frequency is converted by the frequency converter 14 to the transmission path (bidirectional coupler 1
1) and means for determining the degree of deterioration of communication quality due to frequency conversion by the frequency conversion unit 14 (quality evaluation matrix).
28) and means for dynamically obtaining an optimum forward channel to be assigned to frequency conversion based on the degree of deterioration of the communication quality (channel management unit 23), and a completely symmetrical bidirectional N-to-N communication. It is characterized by performing.

(B) A head end that is connected to a broadband transmission line such as a coaxial cable or an optical fiber cable, and divides a used band into a reverse channel and a forward channel to perform bidirectional communication. and the two connected input terminals to the transmission line of (I _1, I _2), the two input terminals (I _1, I ₂₎ disposed annularly between the third was connected to a fourth transmission line Four connection opening / closing means (G) for opening / closing each connection between the two output terminals (O ₁ , O ₂ ) and the annularly arranged input / output terminals (I ₁ , I ₂ , O ₁ , O ₂ ). ₁ ~ G ₄ ) and this 4
Each of the connection opening / closing means (G _{1 to} G ₄ ) has an opening / closing control means (execution control section 21 in the control device 2) corresponding to a designated network configuration, and at least a single branch or a plurality of branches. , A bridge, an interconnecting structure including various networks such as a ring, and means for separating the reverse channel band signal from the transmission line (bidirectional coupler 11) and an arbitrary channel of the separated reverse channel band, Means for frequency-converting to dynamically assigned channels in the forward channel band (frequency converter 14)
A means for sending out the signal whose frequency has been converted by the frequency converting section 14 to the transmission path (bidirectional coupling section 11), and the frequency converting section
A means for obtaining the degree of deterioration of communication quality due to frequency conversion by 14 (quality evaluation matrix 28), and a means for dynamically obtaining an optimum forward channel to be assigned to frequency conversion based on the degree of deterioration of communication quality (channel management Bowl 2
3), and is characterized by performing bidirectional N-to-N communication of perfect symmetry type.

Further, in the headend communication method of the present invention, (c) intelligence for performing completely symmetrical bidirectional N-to-N communication by performing frequency conversion from the reverse channel to the dynamically assigned forward channel over the entire band. Type head-end communication method, the degree of communication quality degradation due to factors including at least interaction and interference between channels due to frequency conversion of each allocation candidate forward channel is obtained, and the degree of communication quality degradation is addressed. Then, an evaluation value determined by at least the reverse channel frequency, the forward channel frequency, the intermediate frequency, and the interfering frequency is obtained, and by referring to this evaluation value, the degree of deterioration in communication quality when each forward channel is assigned is calculated, Assign the forward channel with the least degree of quality degradation, and if this assigned forward channel is blocked, And wherein the assigning seeking less channel with the degree of reduction.

Hereinafter, the structure of the present invention will be described in detail with reference to Examples. FIG. 1 is a block diagram of an intelligent head end device showing an embodiment of the present invention. In FIG. 1, 10 is an intelligent headend (hereinafter referred to as IHE), 1 is a fully symmetric bidirectional N-to-N communication mechanism with a frequency conversion function, and 2 is
A control device for controlling the entire IHE, a storage device 3 for storing various kinds of information and a program executed by the control device 2, a channel dynamic optimal allocation mechanism for dynamically allocating the optimum channel, and a network 5. This is a network configuration control mechanism for creating a topology-free network configuration. A coaxial cable or an optical fiber cable is connected to the terminals 6 and 7. The solid line in FIG. 1 shows the flow of signals, and the broken line shows the flow of control. IHE10 divides the band into a reverse channel and a forward channel in a broadband transmission line such as a coaxial cable or an optical fiber cable,
Two-way communication is performed. Then, the IHE 10 performs a perfect symmetric bidirectional N by a linked operation by organic coupling such as a computer incorporated in the control device 2 referring to matrix data stored in the storage device 3 and performing an update process.
It realizes N-to-N communication, dynamic optimal allocation of channels, and topology-free network configuration.

The fully symmetric bidirectional N-to-N communication mechanism 1 separates only the inverse channel band signal from the transmission line and controls it by the control signal from the control device 2, while using the variable frequency converter to select any channel in the inverse channel band. From the forward channel to an arbitrary channel in the forward channel band, and then the signal is transmitted to the transmission path again, which is a completely symmetrical bidirectional N-to-N communication. The channel dynamic optimum allocation mechanism 4 predicts quality deterioration due to interaction between channels due to frequency conversion, etc., interference, etc., and refers to data such as detected evaluation values and network station management information to evaluate allocation. , Channel escape, reallocation, etc. are performed, and optimal allocation is performed under the dynamic control of the controller 2. The network configuration control mechanism 5 operates a connection circuit having 2 input 2 output terminals and 4 open / close control terminals by a control signal from the control device 2 for a single branch /
It is applicable to all network topologies such as multiple branches (stars), bridges, and rings.

 FIG. 2 is a detailed configuration diagram of FIG.

In FIG. 2, elements 11 to 16 constitute a completely symmetrical bidirectional N-to-N communication mechanism 1, and a channel selection control interface section 8 and a channel selection control section 14n 'built in the frequency conversion section 14 are provided. , And the tuning controller built into the IHE controller 2
30 constitutes the dynamic optimal allocation mechanism 4 of channels. The network configuration control mechanism 5 is shown as it is, and the storage device 3 is shown.
Are included in the IHE control unit 2 and described. A coaxial cable is connected to the terminal 1a, and an external control device is connected to the terminals 1b and 1c.

In the signal flowing through the coaxial cable, the signal in the reverse channel band passes through the bidirectional coupler 11, the signal level is adjusted by the amplifier 12, and then the signal is distributed by the distributor 13 to the signal of the reverse channel number, and the frequency converter is provided. Sent to 14. The frequency converter 14 converts the signal from the distributor 13 into another frequency, and the converted frequency is determined by the control signal input from the channel tuning controller 8. The output signal from the frequency conversion unit 14 is subjected to signal level adjustment by the level adjuster 15, and then combined into a signal in the forward channel band by the mixer 16,
It is transmitted from the bidirectional coupler 11 to the transmission line.

FIG. 3 is a diagram showing a specific example of the frequency conversion unit in FIG. The frequency converter 14 is composed of a plurality of pairs of a frequency converter and a channel tuning controller.

The signal input from the distributor 13 shown in FIG.
The signal is guided to the frequency converter 141 through 3a ₁ , frequency-converted from the reverse channel to the forward channel, and returned to the output terminal 3a ₂ . The other signals from the distributor 13 are similarly input terminals 3b ₁ ,
3c ₁ ... 3n ₁ are input to the converters 142 to 14n and frequency-converted, and the frequency to be converted is determined by a control signal from the channel tuning control units 142 'to 14n'. Note that n is actually 0 to 255.

The frequency converters 141 to 14n have a function of selecting one channel in the reverse channel band and performing frequency conversion to a frequency of a channel having a forward channel band. The channel selection operation is performed by the channel selection control units 141 'to 14n. It is variable by the control signal of '. This tuning control signal is IH controlled by a computer.
The E control unit 2 (see FIG. 2) derives the tuning data obtained by the optimum allocation calculation from the tuning terminal 3z through the tuning control interface unit 8. That is, the frequency conversion from the reverse channel band to the forward channel band is performed by the IHE control unit 2
It is constructed in perfect symmetry over the entire band by the optimum tuning data from.

Generally, when a reverse channel is frequency-converted into a forward channel, there is a deterioration in quality due to interaction between channels and interference. Since the conventional fixed channel allocation method does not realize bidirectional N-to-N communication, it is possible to avoid channel allocation in which quality deterioration is expected in advance. On the other hand, in the completely symmetric N-to-N communication mechanism, it is difficult to predict the quality deterioration in advance because the channel assignment dynamically changes. Furthermore, even if it can be predicted, if the stations connected to the network are asymmetrical, even if control is performed according to the predicted optimum channel selection data, there may be a mismatch. Therefore, in the present invention, these problems have been solved by a dynamic optimal allocation mechanism of channels.

FIG. 4 is a detailed configuration diagram of the IHE control unit in FIG. The station management unit 22 receives the station management information to be notified each time the station is connected to the network, via the connection terminal 4a for connecting to the external interface unit 9 and the communication control unit 29, and the station state matrix 24 of the storage device 3, Transmit / receive channel matrix 25
Memorize each. Station state matrix
Reference numeral 24 represents a communication state between stations and a communicable channel pair. The transmission / reception channel matrix 25 represents the channels that can be transmitted / received and the allocation class for each station. The channel conversion matrix 26 represents the channel conversion capability of the frequency conversion unit 14 from the reverse channel band to the forward channel band, and is stored in the storage device 3 in advance by the channel management unit 23 as IHE specific information. The transmission / reception matrix temporarily stores the transmission / reception channel allocation state. The quality evaluation matrix 28 predicts quality deterioration due to frequency conversion and stores the evaluation value. The evaluation value is determined by the reverse channel frequency f _R , the forward channel frequency f _F , the intermediate frequency f _U , the disturbance frequency f _D , and the frequency conversion method. In response to a channel allocation request from a station, the channel management unit 23 selects a channel that can be used in a station pair or a group to be allocated from the transmission / reception matrix 25, the channel conversion matrix 26, and the transmission / reception channel state matrix 27, and selects each channel. The effect of allocation is calculated with reference to the evaluation value of the quality evaluation matrix 28. As a result, the channel with the highest evaluation value is assigned and the quality evaluation matrix
Update 28. However, when the evaluation values are all low, or when the channel to be allocated has already been allocated, the communication status of the station using the channel is checked from the station status matrix and channel escape is performed to avoid this.

FIG. 5 is a state transition diagram of dynamic optimal allocation of channels according to the present invention. A channel has a fixed allocation class and a variable allocation class attribute, and the latter is a class capable of channel escape. State 1 is an unconnected state, state 2 is a channel notification waiting state, and a transition is made from state 1 to state 2 by a connection notification. However, it returns to the state 1 again due to the timeout. The state is switched from the state 2 to the state 3 by notifying the channel. In addition, the disconnection request returns from state 3 to state 1. When there is an allocation request from the station in the connected state, the allocation evaluation state of state 4 is entered. In the state 4, the assignable channels are obtained from the matrices 25, 26 and 27, the channel having the best quality evaluation is assigned, and then the state 6 is entered.

Now, in the state 4, when the channel to be assigned is in use and is in the variable assignment class, the channel conflict state of the state 5 is entered. In the state 5, the station pair or group using the channel is searched from the station state matrix 24 for another assignable channel, and it is determined whether or not the channel escape is possible. If channel escape is possible, the state is further changed to the reallocation state of state 7 and the channel is reallocated. This makes it possible to dynamically and optimally perform channel allocation according to the situation. When there is no empty channel in the state 4 and the class is the fixed allocation class, the state returns to the connection state of the state 3. In the state 5, if the channel escape is impossible, the state returns to the connection state of the state 3. When the allocation is completed, the state transits to the communication state of state 6, and when the communication ends, the state transits to the state of allocation release of state 8.

By the way, the network topology found in CATV and the like is tree-like because the flow of information is unidirectional. On the other hand, broadband LANs adopt a bus-type architecture, and thus the network topology is a single branch, a tree, or a combination of them in a bridge shape.

The IHE is provided with a network configuration control mechanism 5 in order to integrate both and cope with any network topology.

FIG. 6 is a configuration diagram of a main part of the network configuration control mechanism in FIG. 1, and FIG. 7 is a diagram showing its operation function.

In FIG. 6, I ₁ and I ₂ are channel input terminals, O ₁ and O ₂ are output terminals, and G _{1 to} G ₄ are independently operating switches.
The switches G _{1 to} G ₄ have adjacent input terminals I ₁ and I ₂ and output terminals O ₁ and
Open and close the circuit between O ₂ . When opening and closing the circuit,
First, the control command from the execution control unit 21 of FIG. 4 is sent to the network configuration control unit 5 through the network configuration control interface unit 31,
Transmission to the switches G _{1 to} G ₄ causes operation in the four modes shown in FIG. 7. As shown in FIG. 7, mode 1
Then, since only the switch G ₃ is ON and the rest are all OFF, the signal passes from the input terminal I ₂ to the output terminal O ₂ . This is called bypass mode. Next, in mode 2,
Only the switches G ₃ and G ₄ are turned on and the rest are turned off, so that they pass from the input terminal I ₂ to the output terminals O ₁ and O ₃ . This is called the receive mode. Next, in mode 3, only the switches G ₂ and G ₄ are turned on and the rest are turned off. Therefore, from the input terminal I ₁ to the output terminal O ₂ and from the input terminal I ₂ to the output terminal O ₁ , respectively. pass. This is called a send / receive mode. Next, in mode 4, only the switches G ₁ and G ₃ are turned on and the rest are turned off. Therefore, from the input terminal I ₁ to the output terminal O ₁ and the input terminal I ₂
To output terminal O ₂ . This is called local bus mode.

FIG. 8 is a diagram showing the relationship between the network configuration and the operation mode in the present invention. Here, four IHEs are connected in a ring, and each IHE selects one of the modes 1.4 to be in the inactive, active, degenerate, split / collision operating state. .

In FIG. 8A, each IHE is in the mode 1, that is, the bypass mode, and the network in which each branch operates independently is inactive. Next, each IHE has mode 2 or 3
When it shifts to, it becomes active as shown in FIG. 8 (b), and transmission / reception becomes possible. In the degenerate configuration of FIG. 8 (c), the left side 2
By shifting to the mode 2 and the right two to the modes 3 and 4, some IHEs cannot transmit and receive in the network. That is, it is a case where the network constituent channel is temporarily disconnected from the network because it is used as a local channel in its own IHE. Next, FIG. 8 (d) shows a division / collision configuration, and when a plurality of IHEs are in transmission / reception modes, that is, modes 2 and 3, it is necessary to temporarily divide the network or detect collision. Sometimes this is the configuration.

FIG. 9 is a diagram showing various network configuration examples of the present invention. When the network is configured by the IHE device provided in the network configuration control mechanism 5, a network topology that cannot be achieved by the conventional head end can be realized. FIG. 9 (1) shows a single branch, (2) a plurality of branches (star-shaped), (3) a bridge, and (4) a ring, showing IHE connection configurations.

In the single branch of Fig. 9 (1), IHE performs reverse communication at a reverse channel frequency Fr and forward channel frequency Ff at 1: N bidirectional communication, and at (b) at 1: N bidirectional communication. Each IHE with n lines is shown. In the plurality of branches in FIG. 9 (2), (c) one IHE groups both the reverse channel and the forward channel. Here, each group is divided into two groups, and after being received by two reverse channels, they are respectively transmitted by forward channels.
(D) shows a state where two IHEs cross each other. That is, IHE ₁ and IHE ₂ each perform bidirectional communication by grouping, and the other IHE receives a signal that has passed one of the IHEs. In the bridge shape in FIG. 9 (3), (e) shows a bridge connection by bidirectional, same channel, and double-track cables. That is, the two IHEs are connected to each other by a bidirectional relay line of a double-line cable, and the IHEs that receive directly from each other only pass through the IHEs on the bridge-shaped receiving side, so both are the same. You can send and receive using channels. (F) shows a bridge connection by bidirectional, different channel, and single wire cables. That is, the two IHEs are connected to each other by a single-wire cable, and one IHE, here, IHE ₁ side performs all transmission / reception, and the other IHE ₂ only passes both transmission and reception. Therefore, the two channels use different frequencies. (G) shows a bridge connection by a unidirectional, multi-channel, double-track cable. That is, the two IHEs are unidirectional from each other with a double-track cable, here IHE ₂
Since it is interrupted only in the direction to IHE ₁ , one is transmitted / received on the IHE ₂ side, and the other is transmitted / received on the IHE ₁ side, each uses different channels, and multiple channels are used.

In the ring-shaped connection of FIG. 9 (4), a connection in one direction, the same channel, and a single cable is shown. That is, IHE ₁ , IHE ₂ , IHE ₃ , and IHE ₄ respectively select modes 1 to 4 shown in FIG.
The operation mode and network configuration of (c) can be formed.
In this case, a single cable is used between each IHE and the same channel and unidirectional signal are transmitted.

As described above, by using the intelligent head end of the present invention, various operation modes and network configurations are possible, and the optimum channel can be dynamically allocated.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an intelligent head end (IHE) showing an embodiment of the present invention, FIG. 2 is a more specific configuration diagram of the intelligent head end of FIG. 1, and FIG. FIG. 4 is a configuration example diagram of the frequency conversion unit in FIG. 4, FIG. 4 is a configuration example diagram of the IHE control unit in FIG. 2, FIG. 5 is a state transition diagram of dynamic optimal allocation of channels in the present invention, and FIG. FIG. 7 is a configuration diagram of a main part of the network configuration control mechanism, FIG. 7 is an operation explanatory diagram of the network configuration control mechanism of FIG. 6, and FIG. 8 is a mode and network configuration example diagram of the network configuration control mechanism of FIG. FIG. 9 is a diagram showing various network configuration examples in the present invention. 1: Fully symmetric bidirectional N to N communication mechanism, 2: Control device, 3: Storage device, 4: Channel dynamic optimal allocation mechanism, 5: Network configuration control mechanism, 8: Channel selection control interface section, 9: External Interface part, 10: Intelligent headend (IHE), 11: Bidirectional coupler, 12: Amplifier, 13: Distributor, 14: Frequency converter, 15:
Level adjuster, 16: Mixer, 141-14n: Frequency converter, 14
1'-14n ': Channel tuning control unit, 21: Execution control unit, 2
2: Station management part, 23: Channel management part, 24: Station connection matrix, 25: Station status matrix, 26: Transmission channel matrix, 27: Reception channel matrix, 28: Quality evaluation matrix, 29:
Communication control unit, 30: channel selection control unit, 31: network configuration control interface unit.

Claims (3)

[Claims] 1. A head end which is connected to a broadband transmission line such as a coaxial cable or an optical fiber cable and divides a used band into a reverse channel and a forward channel to perform bidirectional communication. Means for separating the reverse channel band signal, means for frequency-converting any channel of the separated reverse channel band into a channel of a forward channel band that is dynamically assigned, and the signal frequency-converted by the frequency converting means A means for sending to the transmission line, a means for obtaining a degree of deterioration of communication quality due to frequency conversion by the frequency conversion means, and a dynamic optimum forward channel to be assigned to the frequency conversion based on the degree of deterioration of communication quality. At least the means for seeking
An intelligent headend that is characterized by performing fully symmetrical bidirectional N-to-N communication. 2. A head end which is connected to a wide band transmission line such as a coaxial cable or an optical fiber cable and divides a used band into a reverse channel and a forward channel to perform bi-directional communication. Input terminals connected to the transmission line, two output terminals annularly arranged between the two input terminals and connected to the third and fourth transmission lines, and input / output arranged annularly At least a single branch or a plurality of branches is provided, which has four connection opening / closing means for opening / closing each connection between terminals, and means for opening / closing controlling each of the four connection opening / closing means in accordance with a designated network configuration. , Bridge,
A means for separating the reverse channel band signal from the transmission path and an arbitrary channel of the separated reverse channel band while interconnecting in various network configurations including a ring are provided.
A means for frequency-converting to a channel of a forward channel band that is dynamically allocated, a means for sending out a signal whose frequency has been converted by the frequency-converting means to the transmission path, and a decrease in communication quality due to frequency conversion by the frequency-converting means. It has means for obtaining a degree and means for dynamically obtaining an optimum forward channel to be assigned to the frequency conversion based on the degree of deterioration of the communication quality. A characteristic intelligent headend. 3. An intelligent headend communication method for performing completely symmetrical bidirectional N-to-N communication by performing frequency conversion from a reverse channel to a dynamically assigned forward channel over the entire band. The degree of communication quality deterioration due to factors including at least interaction and interference between channels due to frequency conversion of the allocation candidate into each forward channel is obtained, and at least the reverse channel frequency, forward order, is obtained corresponding to the communication quality deterioration degree. An evaluation value determined by the channel frequency, the intermediate frequency, and the interference frequency is obtained, and the evaluation value is referred to to obtain the degree of deterioration in communication quality when the above-mentioned forward channels are assigned. Channels are assigned, and if the assigned forward channels are in a blocked state, the channel with the next lowest degree of communication quality degradation is selected. Intelligent headend communication method, characterized by allocating Te fit.