JP2871544B2 - ATM communication control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FTTH (Fiber
To The Home), FTTC (Fiber To The Curve), H
The present invention relates to an ATM (Asynchronous Transfer Mode) communication control method in a bidirectional interactive system configured using an access network such as FC (Hybrid Fiber Coax).

[0002]

2. Description of the Related Art In recent years, in order to realize various broadband services such as a VOD (Video on Demand) service, a system using an HFC network or the like of a CATV (Cable Television, cable television) operator as a platform has attracted attention. ing.

The CATV system connects a server terminal on the office side with user terminals such as a set-top box and a personal computer installed in each home.
This is a two-way interactive system that enables data such as video information to be delivered directly to each home. When such a broadband service is realized by using such a CATV system platform (an access network such as an HFC network). In consideration of the recent trend toward multimedia data communication and the like, adoption of an ATM-based communication control method capable of transmitting large-capacity data at high speed is effective.

[0004]

However, the conventional ATM communication control system has a configuration in which each user terminal occupies one transmission medium (optical fiber cable, coaxial cable, etc.) and is connected to an ATM exchange. Since it is premised on a data communication system provided, no consideration is given to integration with a multi-access control technique used in an access network such as an HFC network.

FIG. 15 shows an ATM-LAN (ATM-Local Area Network) in a practical stage in a private network.
FIG. 2 is a diagram for explaining a configuration of a conventional ATM-based data communication system using the embodiment. FIG.
FIG. 16 is a diagram for explaining a communication protocol hierarchy in the data communication system shown in FIG.

In the conventional ATM-based data communication system shown in FIG. 15, a personal computer 12 and a set-top box 13 installed in each home are provided.
(Referred to as “user terminals”) are connected to the ATM exchange 10 in a one-to-one relationship.

Then, according to the communication protocol layer 21 shown in FIG. 16, the physical layer, the ATM layer, and the AAL (AT
M Adaptation Layer, ATM adaptation layer), data sequentially passes through upper layers, and predetermined processing is performed on each of the passed data, so that ATM-based data communication (“ATM data communication”) is performed. ").

[0008] The above configuration conforms to the contents of the ATM communication control system discussed in standardization organizations such as the ATM Forum (formally, "The ATM Forum"). As long as you adopt
The number of user terminals accommodated in each of the plurality of switch ports provided in the ATM switch 10 is limited to one, and each of the user terminals occupies one transmission medium and performs two-way communication. .

On the other hand, an ATM-based data communication system configured using an access network such as the HFC network described above is as shown in FIG.

In the data communication system using the access network shown in FIG. 13, a plurality of user terminals (personal computers 12 to 12 ⁽ⁿ⁾ ) are connected to one user terminal.
Since these are multiplexed on the optical fiber cable / coaxial cable 16 and accommodated in the switch port of the ATM switch 10, each user terminal and each switch port of the ATM switch 10 correspond one-to-one. Unlike the conventional data communication system, only the switch port to which input / output is performed is different from the ATM switch 10.
It is not possible to identify to which user terminal the data input / output to / from belongs.

The communication protocol hierarchy in the data communication system shown in FIG. 13 is as shown in FIG. 14. As is clear from FIG.
MAC (Medium Access Co) located below the TM layer
Control on the ATM layer and control on the MAC layer need to be considered because they are established on resources provided by the NTL (medium access control) layer.

Therefore, in order to share the limited resources provided by the MAC layer among a plurality of user terminals, it is expected that resource shortage will frequently occur unless some kind of resource operation with high band use efficiency is performed. However, in the conventional ATM communication control system, no appropriate consideration is given to efficient use of resources.

Further, dynamically determining which switch port of the ATM exchange 10 accommodates a user terminal accommodated in an access network can be achieved by a conventional A
No consideration is given to the TM communication control method.

The present invention has been made in view of the above-mentioned problems, and has been made in view of the above-mentioned problems. It is an object of the present invention to provide a new ATM communication control method for realizing it.

[0015]

In order to achieve the above object, the present invention provides a method for connecting one or more user terminals to an access network.
It connects to an ATM exchange via a network and
ATM communication control system for performing one-way communication,
The resources of the access network are stored in the user terminal.
Resource allocation means variably allocated to each of the
The resource allocating means includes:
A plurality of frequency channels and a plurality of
Number of input / output ports
Assigned, assigned by the resource assigning means
Each of the user terminals uses the resources to transmit data.
An ATM communication control method for performing transmission and reception is provided.

[0016] In the ATM communication control system of the present invention, said resource allocation means, a pre-Symbol resource,
At least including an uplink frequency channel, a time slot on the uplink frequency channel, a downlink frequency channel, and an identifier for identifying the user terminal, and transmitting data using the uplink frequency channel and the time slot. Preferably, data reception is performed using the downlink frequency channel and the identifier.

[0017] Further, the present invention provides an ATM connection which does not reserve a band after the resource allocating means allocates at least an uplink frequency channel, and when the data is actually transmitted, according to a transmission condition of the data. The present invention provides an ATM communication control system characterized in that a time slot is allocated.

Further, according to the present invention, the resource allocation means allocates at least an uplink frequency channel and a time slot for a predetermined band, and then reserves a band.
The present invention provides an ATM communication control system characterized in that a TM connection is set and data is transmitted.

Further, according to the present invention, the resource allocating means allocates at least one of an uplink frequency channel and a downlink frequency channel and then reserves an ATM band for which the bandwidth is reserved.
In performing connection setting, a band on the frequency channel is confirmed, and if the band is insufficient, an already allocated frequency channel is changed to another frequency channel. Provides a control scheme.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram for explaining an example of the configuration of a data communication system for performing ATM data communication via an access network, and the configuration of the data communication system shown in FIG. 13 will be described in further detail. Things.

First, a configuration of a data communication system commonly used in first to fourth embodiments of the present invention described later will be described with reference to FIG.

In the data communication system shown in FIG. 1, an access network 40 provided with a plurality of uplink frequency channels and a plurality of downlink frequency channels includes an ATM network.
It has a configuration in which it is connected to a server terminal 11 via an exchange 10.

The ATM switch 10 and the personal computers 12 to 12 ⁽ⁿ⁾ accommodated in the access network 40 (hereinafter simply referred to as “user terminals”)
They are bidirectionally connected via an optical fiber cable / coaxial cable 16, and data multiplexing / demultiplexing (frequency division or time division) is performed by the analog signal multiplexing / demultiplexing device 15.

That is, the downstream transmission signal of each output switch port of the ATM switch 10 is transmitted to the digital modulator 17.
_The signals are digitally modulated at different frequencies by ₁ to 17 _n and multiplexed on an optical fiber cable / coaxial cable 16 by an analog signal multiplexer / demultiplexer 15.

On the other hand, multiplexed transmission signal upstream over access network 40 are separated by the analog signal multiplexing / separation device 15, are digitally demodulated at different frequencies, respectively, by the digital demodulating apparatus 18 ₁ through 18 _n, The data is input to each corresponding input switch port of the ATM switch 10.

In FIG. 1, the user terminal accommodated in the access network 40 receives a UNI (Us
In the ATM switch 10 that provides an er-Network Interface (user-network interface), an output switch port and an input switch port are separately illustrated for convenience of explanation.

As another configuration in FIG. 1, the switch control function module 19 controls the hardware of the ATM switch 10 and manages the ATM connection according to a call setting procedure (signaling).

The resource management function module 20
Performs control and management of resource allocation on the access network 40.

In the data communication system of FIG. 1, both the switch function control module 19 and the resource management function module 20 are mounted on the ATM switch 10. However, the resource management function module 20 does not necessarily need to be mounted on the ATM switch 10, but may be mounted on another dedicated management device or the like.

In this specification and the drawings, “up” means the direction in which data flows from the user terminal to the server terminal 11, and “down” means that data flows from the server terminal 11 to the user terminal in reverse. It means the direction in which data flows toward.

In the data communication system shown in FIG. 1, the uplink physical medium channel provided by the access network 40 is provided by a combination of frequency division multiplexing and time division multiplexing. That is, time-division multiplexing is performed on each frequency-divided frequency channel and shared by a plurality of user terminals. Actually, each user terminal has the VPI assigned by the resource management function module 20.
An ATM cell in which (Virtual Path Identifier) is described is transmitted using a time slot on a frequency channel for uplink ATM data communication.

The uplink frequency channel and the time slot are also allocated from the resource management function module 20. In addition, only the time slots corresponding to the maximum allowable bandwidth that can be transmitted on the uplink frequency channel are prepared.

Here, the reason why one frequency channel is time-division multiplexed and used is to avoid data collision when a plurality of user terminals sharing the same frequency channel transmit data at the same time. .

On the other hand, the downlink physical medium channel is provided only by frequency division multiplexing. A plurality of user terminals sharing the same downlink frequency channel receive only ATM cells each having their own assigned VPI.

Here, each input / output switch port of the ATM switch 10 corresponds to each frequency channel of the access network 40, and accordingly, the maximum allowable band that can be transmitted on each frequency channel corresponds. Set as the maximum bandwidth of the switch port.

A physical medium channel for uplink / downlink initial subscription control common to all user terminals is prepared in advance. As a specific method of realizing this common physical medium channel, there is a form such as preparing a special frequency channel for initial subscription.

FIG. 2 is a view for explaining a configuration example of a resource management table of the access network 40 in which uplink / downlink frequency channel information managed by the resource management function module 20 shown in FIG. 1 is described. It is.

Referring to FIG. 2, resource management table 3
0 is an input-side switch port number (# 2) in addition to a user name (user1) and an uplink frequency channel (10 MH).
z), uplink VPI (43), information related to the uplink direction such as time slot number (T1, T3), output switch port number (# 8), downlink frequency channel (50 MHz), and downlink VPI (18) Information associated with the down direction. Note that an example of each information managed by the resource management table 30 is shown in parentheses.

FIG. 3 is a diagram for explaining an example of the configuration of the ATM connection bandwidth information table managed by the switch control function module 19 shown in FIG. 1 for each switch port.

Referring to FIG. 3, band information table 31
Is the input-side switch port number (# 4), the input-side VPI
/ VCI (6/4), output switch port number (#
5), output VPI / VCI (6/34), band (3M
bps). Note that an example of each information managed by the band information table 31 is shown in parentheses.

Here, VPI, VCI (Virtual Channel)
l Identifier (virtual channel identifier) is an identifier for selecting a communication path of an ATM cell.

As the band information on the uplink / downlink frequency channel, the frequency channel and the switch port uniquely correspond to each other, so that the switch control function module 19 manages the band information of the ATM connection for each switch port. Is used as it is.

Hereinafter, a specific process of the ATM communication control system according to each embodiment of the present invention, which is performed using the above-described data communication system, will be described.

[0045]

[First Embodiment] FIG. 5 is a flowchart for explaining the processing of the ATM communication control system according to the first embodiment of the present invention.

Referring to FIGS. 1 and 5A, a user terminal connectable to access network 40 is an ATM terminal.
An access network 4 from when a request to start data communication is made to when an ATM connection is established.
The procedure for initial joining to 0 will be described.

When the user terminal has a request to start ATM data communication, first, the ATM terminal performs uplink / downlink ATM transmission.
For data communication, assignment of a frequency channel and a time slot provided by the access network 40 and assignment of an unused VPI on the selected frequency channel are received (step A1).

FIG. 6 shows a step A1 shown in FIG.
FIG. 6 is a diagram for explaining the sequence of the processing of FIG.

Referring to FIGS. 1 and 6, the user terminal comprises:
First, an "initial subscription request message" requesting allocation of frequency channels, time slots, and VPIs (collectively referred to as "access network resources") for uplink / downlink ATM data communication is sent to all user terminals. The data is transmitted to the resource management function module 20 via the common initial subscription control physical medium channel.

A receiving the “initial join request message”
The resource management function module 20 of the TM exchange 10
The resource management information of the access network 40 owned by itself and the bandwidth information of the ATM connection for each switch port held by the switch control function module 19 (since one frequency channel corresponds to one switch port, Bandwidth information)
And the frequency channel with the most available bandwidth,
Alternatively, an appropriate uplink / downlink frequency channel is selected based on another algorithm.

At the same time, a time slot on the selected uplink frequency channel is also secured. The reserved time slot is used for transmitting a message for a call setup procedure, transmitting a further message for controlling access-related network resources, and the like.

In the data communication system shown in FIG. 1, since one frequency channel corresponds to one switch port, it is determined which switch port is accommodated at the same time as the frequency channel is allocated. .

After reserving the selected uplink / downlink ATM data communication frequency channel, the resource management function module 20 assigns a unique VPI to the accommodated switch port as a terminal identifier. In addition,
The resource management function module 20 stores the resource management table 30 of the access network 40 owned by itself.
, Select a VPI that is not used in each switch port.

Then, the resource management function module 20
Notifies the switch control function module 19 of the determined switch port and VPI after the reservation of the selected VPI, and requests the internal setting in the ATM switch 10 relating to the notified switch port and VPI. I do.

When the switch control function module 19 notifies the resource management function module 20 of the completion of the internal setting based on this request, an “initial join response message” is sent to the physical medium for initial join control common to all user terminals. It is transmitted to the user terminal via the channel.

Here, the "initial subscription response message" contains the frequency, time slot number, and VPI for uplink / downlink ATM data communication.

The user terminal that has received the “initial join response message” adjusts the network interface of the user terminal to use the assigned frequency channel for uplink / downlink ATM data communication, and transmits the subsequent ATM. In the header of the cell, the assigned uplink V
PI to be included and the assigned downstream V
Only ATM cells with PI are received.

With the adjustment of the network interface, the user terminal that has received the “initial subscription response message” transmits an “initial subscription confirmation message” to the resource management function module 20 as confirmation that the message has been normally received. .

Upon receiving the “initial subscription confirmation message”, the resource management function module 20 recognizes that the allocated resources have begun to be used effectively.

The "initial subscription request message" transmitted to the resource management function module 20 via a special ATM connection set on the physical medium channel for initial subscription control common to all user terminals is a special message. VPI / VCI (special value prepared for the present invention)
Is desirably composed of one cell in which is described in the header.
Here, the reason why one cell is used is to make it easy to distinguish the same ATM cell transmitted from another user terminal.

Next, referring to FIG. 1 and FIG. 5B, the user terminal connected to the access network 40 and performing the ATM data communication stops all the ATM data communication and is shown in FIG. The procedure from when a request to depart from the control of the data communication system is made to when it is completely departed will be described.

When the user terminal has a request to leave the control of the data communication system shown in FIG. 1, first, all ATM connections are released by a standard call release procedure (step B1).

Then, after releasing the ATM connection,
Release access network resources allocated for uplink / downlink ATM data communication (step B)
2).

FIG. 7 is a flowchart showing the operation of step B2 shown in FIG.
FIG. 6 is a diagram for explaining the sequence of the processing of FIG.

Referring to FIG. 1 and FIG. 7, the user terminal
First, a "leaving request message" requesting release of access network resources is transmitted to the resource management function module 20 via a frequency channel for uplink ATM data communication.

The resource management function module 20 that has received the “leave request message” searches the resource management table 30 of the access network 40 owned by itself and confirms that the corresponding user terminal is registered. Transmits a "Leave Response Message" to the user terminal via a frequency channel for downlink ATM data communication.

The user terminal that has received the “leave response message” internally releases the access network resources allocated up to that point.

The user terminal that has received the “leave response message” transmits a “leave confirmation message” to the resource management function module 20 as confirmation that the message has been received normally.

Then, the resource management function module 20, which has received the “leave confirmation message” from the user terminal,
After deleting the registration of the corresponding user terminal, the switch control function module 19 is notified of the switch port and VPI related to the user terminal whose registration has been deleted, and the internal setting of the ATM switch 10 related to the notified switch port and VPI is released. Request to do so.

When the switch control function module 19 is an ATM
When the internal setting of the exchange 10 is released, the completion of the release of the internal setting is notified to the resource management function module 20, and finally, the resource management function module 20 transmits the frequency channel, the time slot, and the V
Release access network resources such as PI.

[0071]

[Embodiment 2] FIG. 8 is a flowchart for explaining the processing of the ATM communication control system according to a second embodiment of the present invention.

Referring to FIG. 1 and FIG.
A user terminal to which a frequency channel for TM data communication has been allocated has a request to newly set up an ATM connection (also referred to as an “ABR (Available Bit Rate) connection”) that does not reserve a band and perform data communication. From now on, the procedure from setting an ATM connection to performing data communication and releasing the ATM connection will be described.

Note that it is assumed that the user terminal is
(A) and according to the processing of step A1 shown in FIG.
Frequency channels for uplink / downlink ATM data communication are allocated.

When a user terminal establishes an ABR connection and performs data communication, it first transmits a SETUP message for requesting the establishment of an ABR connection to the switch control function module 19, and the switch control function module 19 transmits a standard call. An ATM connection (ABR connection) is set according to a setting procedure (signaling) (step C1).

After the ABR connection is set, the user terminal uses the set ABR connection to set the AT
Immediately before transmitting an M cell, a time slot for transmitting an ATM cell is secured (step C2).

Then, data communication is performed using the secured time slot (step C3). After the data communication is completed, the ATM cell can be transmitted even if the transmitting user terminal does not explicitly request the release of the connection. Release the time slot reserved for the transmission of
4).

After the processing in step C4 is completed, if a request to perform data communication using the same ABR connection occurs within a predetermined period without releasing the ABR connection immediately (“Yes” in step C5) In the case of), after the process of step C2 is executed again to secure a time slot, the above-described steps C3 and C
4 is performed.

If "No" in step C5, the ATM connection (A
The BR connection is released (step C6).

FIG. 9 is a diagram for explaining the sequence of the processing of steps C1 to C6 (in particular, steps C2 and C4) shown in FIG.

First, referring to FIG. 1, FIG. 8 and FIG.
The sequence of the process in step C2 will be described.

It is assumed that an ATM connection (ABR connection) has been set by a standard call setting procedure (step C1).

The user terminal first sets the ABR
Immediately before sending an ATM cell using a connection,
A "time slot allocation request message" for requesting a time slot allocation is sent to the resource management function module 20 via a frequency channel for uplink ATM data communication.
Send to

The "time slot allocation request message" includes transmission conditions such as the number of cells to be transmitted and a peak rate.

The resource management function module 20 that has received the “time slot allocation request message” responds to the transmission conditions in the time-division frame on the frequency channel for uplink ATM data communication allocated to the user terminal. After reserving an empty time slot, a "time slot assignment response message" including information on the reserved time slot is transmitted to the user terminal via a frequency channel for downlink ATM data communication.

The user terminal that has received the “time slot assignment response message” receives the “time slot assignment confirmation message” as confirmation that the message has been normally received.
To the resource management function module 20.

After transmitting the "time slot allocation confirmation message", the user terminal transmits an ATM cell using the allocated time slot (step C3).

Next, referring to FIG. 1, FIG. 8 and FIG.
The sequence of the process in step C4 will be described.

First, the user terminal sends a “time slot release request message” requesting release of the time slot allocated for the transmission of the ATM cell to the upstream AT.
The data is transmitted to the resource management function module 20 via the frequency channel for M data communication.

The "time slot release request message" includes information on the time slot for which release is requested.

Upon receiving the “time slot release request message”, the resource management function module 20 searches the resource management table 30 of the access network 40 owned by itself and finds a corresponding time slot for the user terminal. After confirming that the time slot release response message has been transmitted, the time slot release response message is transmitted to the user terminal via the frequency channel for downlink ATM data communication.

The user terminal that has received the “time slot release response message” receives the “time slot release confirmation message” as confirmation that the message has been normally received.
, The time slot previously allocated is internally released.

On the other hand, upon receiving the “time slot release confirmation message”, the resource management function module 20 sets the resource management table 30 of the access network 40.
After deleting the description of the corresponding time slot from, the time slot is released.

FIG. 9 shows a state where the ATM connection (ABR connection) is finally released according to the standard call release procedure (step C).
6).

[0094]

Third Embodiment FIG. 10 is a flowchart for explaining the processing of the ATM communication control system according to a third embodiment of the present invention.

Referring to FIGS. 1 and 10, a user terminal to which a frequency channel for uplink / downlink ATM data communication has been allocated newly sets up an ATM connection for which a band has been reserved in the uplink direction, and performs data communication. A description will be given of a procedure from when a request to perform an ATM connection is made to when an ATM connection is actually set and data communication is performed, and the ATM connection is released.

It is assumed that the user terminal is a
(A) and according to the processing of step A1 shown in FIG.
Frequency channels for uplink / downlink ATM data communication are allocated.

The user terminal first allocates time slots before setting up an ATM connection,
Uplink AT according to bandwidth required by M connection
A time slot on a frequency channel for M data communication is secured (step D1).

Then, using a standard call setup procedure (signaling), the server terminal 11 and the user terminal
An ATM connection that guarantees a bandwidth in the upstream direction is set (step D2).

After the ATM connection is set, the user terminal checks the VPI / VCI of the ATM connection and V
The correspondence of the time slot reserved for the PI / VCI is stored, and the ATM data communication whose band is guaranteed is performed (step D3).

FIG. 4 shows the VPI / V managed by the user terminal.
FIG. 11 is a diagram for describing a configuration example of a CI-time slot number correspondence table.

Referring to FIG. 4, VPI / VCI-time slot number correspondence table 32 stores VPI / VCI (5/12) of the set ATM connection and time slot numbers (T1, T5, T8). Maintain correspondence. Note that the parentheses show examples of each information managed by the VPI / VCI-time slot number correspondence table 32.

In step D2, if the setting of the ATM connection by the standard call setting procedure (signaling) fails for some reason, the setting for the upstream ATM data communication secured prior to the setting of the ATM connection is made. Time slots on frequency channels are released.

After the data communication in step D3 is completed, the ATM connection is not released immediately, and if a request for data communication is made again within a predetermined period (in the case of "Yes" in step D4), Data communication is continuously performed using the time slot secured by the process of step D1.

If "No" in step D4, the ATM connection is released in accordance with the standard call release procedure (step D5), and the time on the frequency channel reserved for the upstream ATM data communication is subsequently released. The slot is released (step D6).

FIG. 11 is a diagram for explaining the sequence of the processing of steps D1 to D6 (in particular, steps D1 and D6) shown in FIG.

First, the sequence of the process in step D1 will be described with reference to FIGS. 1, 10, and 11.

First, the user terminal sends a “time slot allocation request message” requesting the allocation of a time slot according to the band required by the ATM connection, via the frequency channel for uplink ATM data communication to the resource management function module. 20.

The "time slot assignment request message" includes the bandwidth of the ATM connection to be set on the frequency channel for uplink ATM data communication.

The resource management function module 20 that has received the “time slot allocation request message”
(A) and, according to the processing of step A1 shown in FIG. 6, in the time-division frame on the frequency channel for uplink ATM data communication, the number of empty time slots corresponding to the band is reserved, and then the reserved time slot "Time slot assignment response message" containing information about
To the user terminal via the frequency channel for downlink ATM data communication.

The user terminal that has received the “time slot assignment response message” receives the “time slot assignment confirmation message” as confirmation that the message has been normally received.
To the resource management function module 20.

Next, the sequence of the process in step D6 will be described with reference to FIGS. 1, 10, and 11.

After releasing the ATM connection by the standard call release procedure (signaling) (step D5), the user terminal requests release of the time slot allocated for the released ATM connection. Release request message "
The data is transmitted to the resource management function module 20 via the frequency channel for data communication.

The "time slot release request message" includes a time slot number for which release is requested.

Upon receiving the “time slot release request message”, the resource management function module 20 searches the resource management table 30 of the access network 40 owned by itself, and the corresponding time slot is reserved for the user terminal. After confirming that the time slot release response message has been transmitted, the time slot release response message is transmitted to the user terminal via the frequency channel for downlink ATM data communication.

The user terminal that has received the “time slot release response message” receives the “time slot release confirmation message” as confirmation that the message has been normally received.
Is transmitted to the resource management function module 20, and then the time slot allocated so far is internally released.

On the other hand, upon receiving the “time slot release confirmation message”, the resource management function module 20 sets the resource management table 30 of the access network 40.
Deletes the description of the corresponding time slot from, and releases the time slot.

In the present embodiment, a time slot corresponding to a required bandwidth is secured before setting an ATM connection with a reserved bandwidth. However, a time slot is set after setting an ATM connection. In the case where slots are reserved, there is a sufficient band for setting up an ATM connection, but a sufficient time slot can be reserved by a time slot or the like which is always reserved in an ATM connection that does not reserve a band. However, there is a possibility that an abnormal state occurs in which data communication cannot be actually performed although an ATM connection is set.

[0118]

Fourth Embodiment In the third embodiment, even if a time slot on a frequency channel for uplink ATM data communication is normally secured according to the processing of step D1 shown in FIGS. 10 and 11, The processing in step D2, that is, the setting of the ATM connection may fail.

This is because there is a sufficient band on the upstream frequency channel in which the time slot is normally secured, and the input switch port, that is, the upstream ATM data communication, is used in the standard call setup procedure (signaling). The setting of the ATM connection does not fail due to the shortage of the band on the frequency channel of the above, but the setting of the ATM connection may fail due to the shortage of the band on the output switch port, that is, the frequency channel for the downstream ATM data communication. Because there is.

In the third embodiment, the AT
There is a possibility that the process of step D1 shown in FIGS. 10 and 11 may fail because the time slot for the bandwidth required by the M connection cannot be allocated.

Further, A for requesting a band only in the downlink direction
Even in the case of the TM connection, the necessary bandwidth cannot be secured at the standard call setup procedure (signaling) stage, and the setting of the ATM connection may fail.

The switch control function module 19 for managing the ATM connection in accordance with the standard call setup procedure (signaling) is desired due to lack of bandwidth on the input / output switch port, ie, the frequency channel for uplink / downlink ATM data communication. If it is determined that the setting of the ATM connection is impossible, the call setting procedure (signaling) is interrupted, and the status is notified to the resource management function module 20.

The information notified at this time relates to what uplink / downlink bandwidth value the user terminal is going to set the ATM connection. Upon receiving the notification, the resource management function module 20
Select another frequency channel for ATM data communication having an available resource that satisfies the declared bandwidth value and all the bandwidth values of the ATM connection already set by the user terminal. To change to another frequency channel for ATM data communication.

FIG. 12 is a diagram for explaining a sequence of processing for changing a frequency channel.

The switch control function module 19, which has been requested by the user terminal to set up the ATM connection by the standard call setting procedure (signaling), is desirous of the output switch port, that is, the band shortage on the frequency channel for the downstream ATM data communication. If it is determined that the setting of the ATM connection is not possible, the call setting procedure (signaling) is temporarily suspended, and the resource management function module 2
For 0, it declares the uplink / downlink bandwidth value of the ATM connection for which the setting is requested, and requests a change of the frequency channel already allocated to the user terminal.

The resource management function module 20 having received the request refers to the resource management information of the access network 40 held by itself and the bandwidth information of the ATM connection for each switch port held by the switch control function module 19. Search for another frequency channel having free resources capable of accommodating all of the bandwidth reserved for the user terminal and the newly requested bandwidth in the ATM connection, and if necessary, VPI And time slot selection.

The resource management function module 20 issues a "frequency channel change request message" for urging the user to change from the previously allocated ATM data communication frequency channel to a new ATM data communication frequency channel.
To the user terminal via the frequency channel for downlink ATM data communication.

[0128] The "frequency channel change request message" includes the content of the change related to the frequency channel.

The user terminal that has received the “frequency channel change request message” confirms that the message has been normally received, and receives the “frequency channel change response message” as confirmation.
Is transmitted to the resource management function module 20 via the frequency channel for uplink ATM data communication.

Upon receiving the “frequency channel change response message”, the resource management function module 20 transmits the “frequency channel change confirmation message” to the user terminal as confirmation that the message has been normally received, and then has been allocated to the user terminal. In addition to releasing the frequency channel for the ATM data communication, finally, the switch control function module 19 is notified of the changed switch port and VPI to change the internal setting in the ATM switch 10. Response.

The switch control function module 19 changes the internal setting in accordance with the response from the resource management function module 20, and then restarts the temporarily interrupted call setting procedure (signaling).

On the other hand, the user terminal that has received the “frequency channel change confirmation message” transmits and receives ATM cells on a new frequency channel in place of the frequency channel for the ATM data communication that has been allocated so far. Tune the interface.

In this embodiment, the processing for setting the ATM connection with reserved bandwidth has been mainly described. However, the processing shown in FIG. 12 is the same as that shown in FIG. 10 in the third embodiment. The present invention is also applicable to a case where a necessary time slot cannot be secured in the process of step D1.

As described above, according to the present embodiment, it is possible to dynamically change the assignment of the frequency channel (change of the switch port of the ATM exchange 10 accommodating the user terminal).

The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and includes various embodiments according to the principle of the present invention.

[0136]

As described above, according to the present invention, ATM-based data communication can be realized on an access network in which multi-access control is performed.

Further, according to the present invention, the input / output port of the ATM exchange is made to correspond to the frequency channel on the access network, and a user equipment connectable on the access network is provided with a frequency channel if necessary. ,
Since time slots and identifiers are assigned, limited resources of the access network can be effectively shared among many user terminals.

Further, according to the present invention, when setting an ATM connection that does not reserve a band, a fixed time slot is not always allocated, but a time slot required only when data transfer is actually performed is allocated. Therefore, limited resources of the access network can be effectively shared.

Further, according to the present invention, when setting an ATM connection with a reserved band, a data slot with a guaranteed communication quality is performed in order to secure a time slot according to a required band in advance. be able to.

Further, according to the present invention, a frequency channel is dynamically allocated to a user terminal not only during the initial subscription to the access network but also during the subscription.
The limited resources of the access network can be used very effectively.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a configuration of a data communication system that performs ATM data communication via an access network.

FIG. 2 shows a resource management function module 20 shown in FIG.
FIG. 3 is a diagram for explaining an example of the configuration of a resource management table of an access network 40 managed by the system.

FIG. 3 is a switch control function module 19 shown in FIG.
FIG. 6 is a diagram for explaining an example of the configuration of a band information table of an ATM connection managed by the ATM.

FIG. 4 is a diagram for explaining a configuration example of a VPI / VCI-time slot number correspondence table managed by the personal computers 12 to 12 ⁽ⁿ⁾ shown in FIG. 1;

FIG. 5 is a flowchart for explaining processing of the ATM communication control method according to the first embodiment (Embodiment 1) of the present invention.

FIG. 6 is a diagram for explaining the sequence of the process of step A1 shown in FIG.

FIG. 7 is a diagram for explaining the sequence of the process of step B2 shown in FIG. 5 (B).

FIG. 8 is a flowchart illustrating processing of an ATM communication control method according to a second embodiment (Embodiment 2) of the present invention.

FIG. 9 is a diagram for explaining a sequence of processing in steps C1 to C6 shown in FIG. 8;

FIG. 10 is a flowchart for explaining processing of an ATM communication control method according to a third embodiment (Embodiment 3) of the present invention.

FIG. 11 is a diagram for explaining a sequence of processing in steps D1 to D6 shown in FIG. 10;

FIG. 12 is a diagram illustrating a sequence of a process for changing a frequency channel according to a fourth embodiment (Embodiment 4) of the present invention. .

FIG. 13 is a diagram illustrating an example of a configuration of a data communication system that performs ATM data communication via an access network.

FIG. 14 is a diagram illustrating a configuration of a communication protocol layer in the data communication system shown in FIG.

FIG. 15 is a diagram for explaining a configuration of a conventional data communication system using an ATM-LAN mode.

FIG. 16 is a diagram for explaining a configuration of a communication protocol layer in the conventional data communication system shown in FIG.

[Explanation of symbols]

Reference Signs List 10 ATM switch 11 Server terminal 12, 12 ', ..., 12 ⁽ⁿ⁾ Personal computer 13 Set-top box 14 Display 15 Analog signal multiplexing / demultiplexing device 16 Optical fiber cable / coaxial cable 17 Digital modulator 18 Digital demodulator 19 Switch control Function module 20 Resource management function module 21, 22 Communication protocol layer 30 Resource management table 31 Band information table 32 VPI / VCI-time slot number correspondence table 40 Access network

Claims (6)

(57) [Claims] An ATM communication control system for connecting one or a plurality of user terminals to an ATM exchange via an access network and performing bidirectional data communication, wherein resources of the access network are allocated to the user. Resource allocating means for variably allocating to each of the terminals, wherein the resource allocating means allocates the plurality of frequency channels of the access network and the plurality of input / output ports of the ATM switch so as to correspond to each other, The ATM communication control method, wherein each of the user terminals transmits and receives data using the resources allocated by the resource allocating means. 2. An ATM communication control system for connecting one or a plurality of user terminals to an ATM exchange via an access network and performing bidirectional data communication, wherein resources of the access network are allocated to the user. Resource allocating means variably allocated to each of the terminals, and resource releasing means for releasing resources allocated to each of the user terminals, comprising, as the resources, at least an uplink frequency channel; Including a time slot, a downlink frequency channel, and an identifier for identifying the user terminal, transmitting data using the uplink frequency channel and the time slot, and using the downlink frequency channel and the identifier. The resource allocation means, at least Ri to set the ATM connection which does not reserve bandwidth after allocating frequency channels actually allocated the time slot corresponding to the transmission condition of the data when transmitting the data, and,
After allocating at least an uplink frequency channel and a time slot for a predetermined band, setting up an ATM connection for which a band has been reserved and performing data transmission, the resource release unit, when the data transmission is completed, The ATM communication control method, wherein the allocated time slot is released. 3. The resource includes at least an uplink frequency channel, a time slot on the uplink frequency channel, a downlink frequency channel, and an identifier for identifying the user terminal, wherein the uplink frequency channel and the time An ATM connection that transmits data using a slot and receives data using the downlink frequency channel and the identifier, and wherein the resource allocation unit allocates at least an uplink frequency channel and does not reserve a band. settings of, when transmitting the actual data, ATM communication control method according to claim 1, characterized in that to assign the time slots in accordance with the transmission condition of the data. 4. The ATM communication control system according to claim 3 , wherein said allocated time slot is released when said data transmission is completed. 5. The resource includes at least an uplink frequency channel, a time slot on the uplink frequency channel, a downlink frequency channel, and an identifier for identifying the user terminal, wherein the uplink frequency channel and the time While transmitting data using a slot, and receiving data using the downlink frequency channel and the identifier, the resource allocating means allocated at least an uplink frequency channel and a time slot for a predetermined band later,
The ATM communication control method according to claim 1, wherein an ATM connection with a reserved band is set to transmit data. 6. The resource includes at least an uplink frequency channel, a time slot on the uplink frequency channel, a downlink frequency channel, and an identifier for identifying the user terminal, wherein the uplink frequency channel and the time While transmitting data using a slot and performing data reception using the downlink frequency channel and the identifier, the resource allocating means allocated at least one of the uplink frequency channel and the downlink frequency channel Later, when setting up an ATM connection for which a band has been reserved, the band on the frequency channel is checked, and if the band is insufficient, the already allocated frequency channel is changed to another frequency channel. The ATM communication control method according to claim 1, wherein: