JP2000324198A - Variable data rate transmitting device and variable data rate transmitting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable data rate transmitting device which minimizes the rapid drop of the throughput involved by the deterioration of a line and a variable data rate transmitting method. SOLUTION: This device is provided with a RADSL(rate adaptive asymmetric digital subscriber line) modem part 206 whose transmission speed varies in accordance with a line quality situation, a control part 205 reading the current line operation state from the part 206, a physical layer processing art 201 which forcedly generates collision according to control from the part 205, a MAC layer processing part 202 executing collision detection and the confirmation of frame propriety and a MAC address detecting part 207 which detects a self-station address and notifies the part 205 of a frame length when a MAC address is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission control technique, and more particularly to a variable data rate type transmission apparatus and a variable data rate transmission method for minimizing a sharp decrease in communication throughput due to line quality deterioration.

[0002]

2. Description of the Related Art As an example of a high-speed data communication network, ITU
B-ISDN (Broadb
and Integrated Services D
digital network). B-ISDN
The transfer mode used by ATM is Asynchronous
A non-transfer mode (asynchronous transfer mode) in which information is divided into 53-byte packets called cells, and relay connection is made between ATM switches to perform variable bit rate (variable bit-rate) transmission. Multiplexing of calls by service is possible.

[0003] In ATM, AAL (ATM Adaptation) defined by the ITU-T recommendation.
(Layer) 2, 3/4, 5 and other variable speed services enable flexible communication speeds from low to high. In addition, by performing label multiplexing of cells, a statistical multiplexing effect is obtained in which temporal fluctuations in transmission rates of individual calls are absorbed, and economic use of a communication network can be expected.

In a communication network using an ATM, flow control is not performed between nodes, and an ATM switch controls a transmission rate of image data or the like by linear prediction of a transmission amount to be transmitted. However, the form of information generation, the duration of information generation, and the like vary depending on media such as audio and images, applications in which the information is used, and the like, and the amount of generated information varies greatly. For this reason, it is difficult to predict the state of occurrence. When such information is transmitted as data, the degree of multiplexing is low, so that a statistical multiplexing effect cannot be obtained. As a result, temporary network elements such as switches, multiplexers, transmission links, etc. Congestion may occur due to traffic concentration and buffer overflow.

[0005] For this reason, traffic shaving by a transmitting terminal has been conventionally known as one of the measures against congestion in a communication network. This traffic shaving technique is described in IEICE Technical Report, SSE94-6, IN94-6 (1
994-04), The Institute of Electronics, Information and Communication Engineers, Masahiro Inoue et al.
Name, “Study of Variable Rate Video Transmission System Using Traffic Shaving”, p. 31-36.
Traffic shaving is a continuous generation of cells,
In addition, a state in which the transmission rate increases instantaneously is suppressed. To this end, buffering is performed on the cell transmitting side, and cells are transmitted at time intervals to control the band. Such prior art is
Since the transmission rate must be calculated every time input information is generated or at regular intervals, complicated hardware for performing the calculation is required, and there is a problem in that the load on peripheral processing is large.

As a conventional technique for solving such a problem, there is, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 9-8814. That is, JP-A-9-881
In the prior art described in Japanese Patent Laid-Open No. 4 (1994) -204, a data storage unit for storing data to be transmitted, a data output unit for outputting data stored in the data storage unit to a transmission path, and a transmission rate increases with time. A data transmission device comprising a control unit for controlling a data amount per unit time to a transmission line of a data output unit, the data transmission device transmitting data to the transmission line and increasing a transmission rate. Then, the next data is transmitted to the transmission path, and the control means increases the transmission rate at regular intervals or increases the transmission rate at regular intervals. With this, on the data transmitting side, a drastic increase in the amount of information at the start of communication or the like can be suppressed with a simple configuration, so that cell discard due to congestion on the communication network side can be prevented, and high quality transmission and An effect that economical transmission can be performed is disclosed.

[0007]

However, the above prior art has the following problems. First, the first problem is ANSI (American Standards Association) T1.413.
Issue 2 and ITU-T (International Advisory Committee on Radio Communications) 992.1, ITU-TG. 992.2
A transmission apparatus (RADSL (Rate adapti) that changes the transmission rate in accordance with the line quality status specified in
ve Asymmetric Digital Sub
scriber Line) modem)
When the line quality is rapidly deteriorated due to leakage of radio waves or the like, retraining occurs and the line speed is reduced to a line speed according to the current line state.

A second problem is that the conventional transmission apparatus is connected because the line speed is reduced when the terminal side interface conforms to the IEEE (American Institute of Electrical and Electronics Engineers) 802.3 standard. Depending on the amount of data from the terminal, data may be discarded. The third problem is that OSI (Open System)
The UDP (User Data) is added to the network layer in the ems Interconnection reference model.
In the case of using the protocol (gram protocol), the fact that data is discarded means that UDP does not have a function of error control or delivery acknowledgment, and therefore it is necessary for the application to cope with it. The fourth problem is the TCP (Transmission Control).
l Protocol), the end-to-end error assurance by TCP is performed, so that the throughput is greatly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a variable data rate type transmission apparatus capable of minimizing a sharp decrease in communication throughput due to line quality deterioration. And a variable data rate transmission method.

[0010]

The gist of the present invention is a variable data rate type transmission apparatus for minimizing a sharp decrease in communication throughput due to line quality deterioration. A RADSL modem unit whose transmission speed is variable according to a situation, a control unit which reads from the RADSL modem unit a line availability, a current transmission speed, and / or a current line quality as a current line operation state; A physical layer processing unit for forcibly generating a collision according to control from the unit, a MAC layer processing unit for executing collision detection and frame validity confirmation, and a MAC address set by the control unit. A MAC address detection unit for notifying the control unit of the detection of the own station address and the frame length upon detection, and a data frame from the MAC layer processing unit. The data in the buffer sequentially stored to the storage and temporally oldest in buffer RADS
A transmission buffer processing unit for transmitting to the L modem unit in synchronization with the clock of the RADSL modem unit; and a buffer for sequentially storing data frames from the RADSL modem unit in synchronization with the clock of the RADSL modem unit and storing the data frames. A variable data rate type transmission device is provided with a reception buffer processing unit for transmitting data in a buffer to the MAC layer processing unit in ascending order of time. The gist of the invention described in claim 2 is that the control unit has a function of reading a buffer usage rate of the transmission buffer processing unit. Exists in the device. The gist of the invention according to claim 3 is that, when the MAC address detection unit detects the MAC address set by the control unit, the MAC address detection unit notifies the control unit of a notification of detecting the own station address and a frame length. The variable data rate type transmission apparatus according to claim 1, wherein The gist of the invention described in claim 4 is that the physical layer processing unit is an IEEE 80
2. The variable data rate transmission device according to claim 1, further comprising a function of terminating the physical layer of the 2.3 standard and decoding a received data signal into received data. The gist of the invention described in claim 5 is that the physical layer processing unit detects a collision with the MAC layer processing unit and confirms the validity of the frame, decomposes the received frame, and determines the destination address. The variable data rate type transmission apparatus according to claim 1, further comprising a function of determining whether the packet is addressed to the own station, performing an error check, and transmitting a frame to the transmission buffer processing unit. Exist. The gist of the invention described in claim 6 is that the RADSL modem section includes ANSIT1.413 Is
Sue 2 and ITU-TG. 992.1, ITU
-TG. An RADSL modem specified in 992.2, which has a function of constantly measuring the line quality, a function of notifying the terminal device of the line quality of the own station, and an instruction of the control unit when the quality is deteriorated. 2. The variable data rate transmission device according to claim 1, wherein the variable data rate transmission device has at least one of a function of stopping a transmission clock and activating a training based on the transmission quality and providing a transmission speed according to the line quality. The gist of the invention described in claim 7 is that the transmission buffer processing unit has a function of sequentially calculating a buffer usage rate. Exist. The gist of the invention according to claim 8 is that when the line quality is deteriorated and data transmission with a preset quality becomes impossible, the MAC address set by the control unit is sent from the MAC address detection unit. When detecting, the control unit sets the MAC
The layer processing unit is forcibly requested to generate a collision for a time corresponding to the length length, and after the request, requests the RADSL modem unit to stop transmitting the transmission clock and start training. A variable data rate type transmission apparatus according to any one of claims 2 to 7, wherein The gist of the invention according to claim 9 is that the control unit confirms the end of the training of the RADSL modem unit and the transmission speed, monitors the usage rate of the transmission buffer in the transmission buffer processing unit, and the control unit Set the MAC address to the MAC
3. The apparatus according to claim 2, wherein the control section is configured to forcibly cause a collision with the MAC layer processing section for a time corresponding to a length length when the control section detects the address from the address detection section. 9. The variable data rate transmission device according to any one of claims 1 to 8, wherein Claim 10
SUMMARY OF THE INVENTION The gist of the invention described in is a variable data rate transmission method for minimizing a sharp decrease in communication throughput due to line quality deterioration, and a RADSL modem step in which a transmission speed is varied according to the line quality situation. A control step of reading out the availability of the line, the current transmission speed, and / or the current line quality from the RADSL modem step as a current line operation state, and forcibly performing a collision in accordance with the control from the control step. A physical layer processing step that occurs, a MAC layer processing step that executes collision detection and frame validity confirmation, and detects a local address and a frame length when the MAC address set by the control step is detected. A MAC address detection step of notifying the control step, and a data frame from the MAC layer processing step sequentially buffered. A transmission buffer processing step of transmitting the stored data in the buffer in the order of the stored time to the RADSL modem step in synchronization with the clock of the RADSL modem step; A variable data rate transmission characterized by comprising a receiving buffer processing step of sequentially storing data frames from the modem step in a buffer and transmitting the data in the buffer to the MAC layer processing step in the chronological order of the stored time. Be in the way. According to an eleventh aspect of the present invention, there is provided the variable data rate transmission method according to the tenth aspect, wherein the control step includes a step of reading a buffer usage rate in the transmission buffer processing step. The gist of the invention according to claim 12 is that, when the MAC address detecting step detects the MAC address set in the control step, a step of notifying the control step of a notification of detecting the own station address and a frame length. 11. The variable data rate transmission method according to claim 10, comprising: The gist of the invention described in claim 13 is that the physical layer processing step is an IEEE80
The variable data rate transmission method according to claim 10, further comprising a step of terminating a physical layer of the 2.3 standard and a step of decoding received data from a received data signal. The gist of the invention described in claim 14 is that, in the physical layer processing step, a collision detection and a frame validity check are performed in the MAC layer processing step, and a destination address is decomposed by disassembling a received frame. 11. The variable data rate transmission method according to claim 10, further comprising a step of determining whether the packet is addressed to the own station, performing an error check, and transmitting a frame to the transmission buffer processing step. The gist of the invention described in claim 15 is that the RADSL modem step is performed by ANSI T1.4.
13 Issue 2 and ITU-T G.13. 992.
1, ITU-TG. RA specified in 992.2
A step of executing a processing step of the DSL modem, a step of constantly measuring the line quality, a step of notifying the remote station of the line quality of the own station, and a step of notifying based on an instruction of the control step when the quality is deteriorated. 2. The method according to claim 1, further comprising at least one of a step of stopping the transmission clock and activating the training to achieve a transmission speed according to the line quality.
0. The gist of the invention according to claim 16 resides in the variable data rate transmission method according to claim 10, wherein the transmission buffer processing step includes a step of sequentially calculating a buffer usage rate.

[0011]

FIG. 1 is a functional block diagram for explaining a variable data rate type transmission apparatus 102 according to one embodiment of the present invention. 1, reference numeral 201 denotes a physical layer processing unit, 202 denotes a MAC layer processing unit, 203 denotes a reception buffer processing unit, 204 denotes a transmission buffer processing unit, 205 denotes a control unit, 206 denotes a RADSL modem unit, and 207 denotes a MAC.
4 illustrates an address detection unit. Referring to FIG. 1, variable data rate type transmission apparatus 102 of the present embodiment includes a physical layer processing unit 201, a MAC layer processing unit 202, a reception buffer processing unit 203, a transmission buffer processing unit 204, a control unit 20
5, a RADSL modem unit 206 and a MAC address detection unit 207.

The control unit 205 has a RADSL (Rate
adaptive Asymmetric Digit
al Subscriber Line) Modem section 20
6, a function of reading out the current line operation status (line availability, current transmission speed, current line quality), and
The transmission buffer processing unit 204 has a function of reading a buffer usage rate. The physical layer processing unit 201 includes the control unit 20
5 has a function of forcibly generating a collision in accordance with the control from step 5. The MAC layer processing unit 202 has a function of detecting a collision and confirming the validity of a frame. The MAC address detection unit 207 includes the control unit 2
The function of notifying the control unit 205 of the detection of the own station address and the frame length when the MAC address set by the control unit 205 is detected, and the MAC
When an address is detected, the control unit 205 has a function of notifying the control unit 205 of a notification that the own station address has been detected and a frame length. The physical layer processing unit 201 terminates the physical layer (Layer 1) of the IEEE802.3 standard, decodes the received data signal into the received data, and outputs a collision detection and frame detection to the MAC layer processing unit 202. It has a function of checking the validity, decomposing the received frame to determine the destination address, determining whether the frame is addressed to its own station, performing an error check, and transmitting the frame to the transmission buffer processing unit 204. I have. The reception buffer processing unit 203
RAD synchronized with the clock of the RADSL modem unit 206
A function of sequentially storing the data frames from the SL modem unit 206 in the buffer, and transmitting the data in the buffer to the MAC layer processing unit 202 in the order of the stored time, and
It has a function of sequentially calculating the buffer usage rate. The transmission buffer processing unit 204 sequentially stores the data frames from the MAC layer processing unit 202 in a buffer,
In synchronization with the clock of the modem unit 206, the stored data in the buffer is stored in the RADSL modem unit 2 in chronological order.
06 and a function of sequentially calculating the buffer usage rate. RADSL modem section 206
Is the ANSI (American National Standards Institute) T1.413 Iss
ue2 and ITU-T (International Advisory Committee on Radio Communications)
G. FIG. 992.1, ITU-TG. A transmission device (RADSL modem) whose transmission speed is variable in accordance with the line quality status specified in 992.2, a function of constantly measuring the line quality, and indicia for the opposite device.
a function of notifying the line quality of the own station using n bits or the like; and, when the quality is deteriorated, the transmission clock is stopped and training is started based on the instruction of the control unit 205 to perform transmission speed and transmission speed according to the line quality. Function.

In the variable data rate type transmission apparatus 102 having such a hardware configuration, when the line quality is deteriorated and data transmission with a preset quality becomes impossible, the MAC address set by the control unit 205 Is detected from the MAC address detection unit 207, the control unit 205 requests the MAC layer processing unit 202 to forcibly generate a collision for a time corresponding to the length length,
After the request, it requests the RADSL modem unit 206 to stop sending the transmission clock and start training. In addition, the control unit 205 checks the end of the training of the RADSL modem unit 206 and the transmission speed, monitors the usage rate of the transmission buffer in the transmission buffer processing unit 204, and changes the MAC address set by the control unit 205 to M
When the detection is performed from the AC address detection unit 207, the control unit 205 forcibly causes the MAC layer processing unit 202 to collide for a time corresponding to the length length.

FIG. 2 is a network configuration diagram for explaining an embodiment of a communication network to which the variable data rate transmission device 102 of FIG. 1 is applied. In FIG. 2, 101 is a server, A is a center-side transmission device 102 connected by a transmission line 106, B is a remote-side transmission device 102 and 103 connected by a transmission line 106, is a telephone,
104 is a POTS, 105 is a terminal, 106 is a transmission line, 1
Reference numeral 07 denotes an Ethernet line, and reference numeral 102 denotes a variable data rate transmission device according to the present embodiment.

The server 101 is a terminal equipped with an IEEE802.3 interface, and is a 10Base-
The transmission device A (102) on the center side and the transmission device B (10
2) is connected. The telephone 103 is an analog telephone 103 that uses a voice band. POTS104
Is a filter for separating the voice band from the band used by the RADSL modem, and is connected to the transmission line 106.

Next, the operation (variable data rate transmission method) of the variable data rate type transmission apparatus 102 of the present embodiment will be described with reference to FIGS. Now, the transmission device A (102) on the center side and the transmission device B (102) on the remote side
, The transmission speed from the transmission device B (102) on the remote side to the transmission device A (102) on the center side is 1 Mbps, the buffer size of the transmission buffer in the transmission buffer processing unit 204 is 256 Kbytes, 1500 LLC frames
The description proceeds assuming a byte configuration.

At this time, the transmission buffer in the transmission buffer processing unit 204 according to the present embodiment has a buffer capacity for 170 frames. The configuration of the MAC frame is 1526 bytes. Excluding the frame, the MAC frame has 1518 bytes.

The transmission capacity between the transmission device A (102) on the center side and the server 101 and the transmission device B (1) on the remote side
02)-The sum of the transmission capacities between the servers 101 is, on average, within the range of the transmission speeds of the transmission device A (102) on the center side and the transmission device B (102) on the remote side. At this time, the transmission capacity from the transmission device A (102) on the center side and the transmission device B (102) on the remote side to the server 101 is 1 Mbps or less on average, and the transmission device A (102) from the server 101 and the transmission device on the remote side are transmitted from the server 101. Transmission capacity for device B (102) is 6Mb on average
ps or less. However, this may be exceeded at peak times.

Now, consider a case where the line quality of the transmission line 106 suddenly deteriorates and the quality deteriorates from a preset value. At this time, the control unit 205 requests the RADSL modem unit 206 to stop the transmission clock and start training. When the training occurs, the line disconnection occurs until the training ends. The time for this line disconnection is about 10 seconds. When communication is interrupted for 10 seconds in this manner, it is assumed that 60 Mbps data flows into the transmission device A (102) on the center side in 10 seconds, and the number of frames is 60 Mbps / (1518 *).
8) = 4940 frames, and the capacity of the transmission buffer in the transmission buffer processing unit 204 of the transmission device A (102) on the center side is only 170 frames, so 4
770 frames of data will be discarded.

In the present embodiment, the control unit 205 of the transmission device A (102) on the center side transmits the current line operation state (line availability, current transmission speed, current quality) to the transmission device A on the center side. (102) RADSL modem section 20
6 from the transmission line 10 based on a preset value.
It is determined whether the line quality has deteriorated. If the line quality has deteriorated, the transmission clock stop and the training start are requested to the RADSL modem unit 206 of the transmission apparatus A (102) on the center side. When the MAC address is detected from the MAC address detection unit 207 of the transmission device A (102) on the center side, the MAC layer processing unit 2 of the transmission device A (102) on the center side for a time corresponding to the frame length.
02 is forcibly controlled to generate a collision, and the above operation is continued until the line disconnection is released. For example, if the frame length is 1500 bytes,
The collision occurrence time is 1500 bytes * 8 * 0.1
μsec = 1.2 msec. Accordingly, the server 101 can perform retransmission control after confirming that a collision has occurred in the MAC layer.

Next, the training is completed, the transmission speed after completion is reduced, the transmission speed from the center side transmission device A (102) to the remote side transmission device B (102) is 4 Mbps, and the remote side transmission device. It is assumed that the transmission speed from B (102) to transmission device A (102) on the center side has changed to 800 kbps. At this time, the transmission capacity from the center-side transmission device A (102) to the server 101 is 1 Mbps on average, and the transmission capacity from the server 101 to the center-side transmission device A (102) is 6 Mbps on average. A speed difference occurs.

In the transmission device A (102) on the center side, the number of frames generated due to a speed difference per second is 2 Mbps.
/ (1518 * 8) = 165 frames, and the capacity of the transmission buffer in the transmission buffer processing unit 204 is 17
Since there is only 0 frames, the frame data will be discarded if it exceeds 1 second.

In the transmission device A (102) on the center side,
The control unit 205 reads the current line operation status (line availability, current transmission speed, current line quality) from the RADSL modem unit 206, and calculates the difference between the current transmission speed and the transmission speed before the change. , The MAC address of the own station according to the time until the frame generated due to the speed difference is discarded.
When the address is detected from the address detection unit 207, the MAC layer processing unit 202 is controlled to forcibly generate a collision for a time corresponding to the frame length. Accordingly, the server 101 can confirm that a collision has occurred in the MAC layer and perform retransmission control.

Further, when the training is completed and the difference in transmission speed after completion is small, the transmission device A (10
From 2), the transmission speed to the remote-side transmission device B (102) is 5.968 Mbps, and the remote-side transmission device B (102)
Assuming that the transmission rate from (102) to the transmission device A (102) on the center side has changed to 968 kbps, the transmission capacity from the transmission device A (102) on the center side to the server 101 is 1 Mbps on average, and the transmission capacity from the server 101 to the center is average. Since the transmission capacity for the transmission device A (102) on the side is 6 Mbps on average, a speed difference occurs. At this time, in the transmission device A (102) on the center side, 1
The number of frames generated by the speed difference per second is 32 kbps / (1
518 * 8) = 3 frames, and the capacity of the transmission buffer of the transmission buffer processing unit 204 of the transmission device A (102) on the center side is 170 frames, so that frame data discard does not occur until the time exceeds 56 seconds. become.

In the transmission device A (102) on the center side,
The control unit 205 reads the current line operation status (line availability, current transmission speed, current quality) from the RADSL modem unit 206, and calculates the difference between the current transmission speed and the transmission speed before the change, In addition, the usage rate of the transmission buffer processing unit 204 is read. For example, when the usage rate exceeds 95%, when the MAC address detection unit 207 detects the own station MAC address, the MAC layer processing unit 202 is notified of the frame length. Control is performed so that a collision is forcibly generated only for a corresponding time. As a result, the server 101 side
In the MAC layer, it is possible to confirm that a collision has occurred and perform retransmission control.

As described above, according to the above embodiment, the following effects can be obtained. The first effect is O
Even when data is discarded when UDP is used for the network layer in the SI reference model, UDP does not have a function of error control or delivery acknowledgment, so that there is no need for an application to handle it. The second effect is that even in the case of using TCP, since end-to-end errors are guaranteed by TCP, it is possible to solve a case where the throughput is extremely reduced. The third effect is that the training associated with the deterioration of the line quality is executed, so that even if a line disconnection occurs, the state of the line disconnection is confirmed and a collision is forcibly generated. Retransmission control at the layer can be performed, so that discarded frames can be minimized. The fourth effect is that the training associated with the deterioration of the line quality is executed. Therefore, even if the transmission speed is reduced, if the speed difference after the change is large, the current transmission speed is read and the transmission speed before the change is read. And the difference between the calculated speed difference and the time until the frame discard occurs.
A collision can be forcibly generated, and in response to this, the server 101 can execute retransmission control in the MAC layer and can avoid retransmission control in an upper layer protocol, thereby minimizing a decrease in throughput. It is to be suppressed. The fifth effect is that since the training accompanying the line quality deterioration is executed, even if the transmission speed is reduced, if the speed difference after the change is small, the current transmission speed is read and the transmission speed before the change is read. In addition to calculating the difference, the usage rate of the transmission buffer in the transmission buffer processing unit 204 can be read and a collision can be forcibly generated.
As a result that retransmission control is performed in the MAC layer and retransmission control is not performed in a higher-order protocol, a decrease in throughput can be minimized, and a buffer capacity can be minimized. As a result, delay time can be reduced. Can be shortened. The sixth effect is MA
Only when the C-address is detected and the MAC address of the own station is detected, the forced collision can be generated, so that the communication in the LAN is not affected. The seventh effect is that the line quality is constantly monitored, and the transmission clock is stopped even if the transmission quality is deteriorated from a preset value. The data can be rescued, and a collision can be forcibly generated. In response to this, the server 101 performs retransmission control in the MAC layer and does not involve retransmission control in the upper layer protocol. As a result, a decrease in throughput can be minimized.

It should be noted that the present invention is not limited to the above embodiments, and it is clear that the embodiments can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In each drawing, the same components are denoted by the same reference numerals.

[0028]

Since the present invention is configured as described above, the following effects can be obtained. The first effect is O
Even when data is discarded when UDP is used for the network layer in the SI reference model, UDP does not have a function of error control or delivery acknowledgment, so that there is no need for an application to handle it. The second effect is that even in the case of using TCP, since end-to-end errors are guaranteed by TCP, it is possible to solve a case where the throughput is extremely reduced. The third effect is that since the training accompanying the line quality deterioration is executed, even if the line is disconnected, the state of the line disconnection is confirmed and the collision is forcibly generated, and the server side performs the MAC layer operation. Can be performed, and as a result, discarded frames can be minimized. The fourth effect is that the training associated with the deterioration of the line quality is executed. Therefore, even if the transmission speed is reduced, if the speed difference after the change is large, the current transmission speed is read and the transmission speed before the change is read. Can be forcibly generated in accordance with the time until frame discard due to the calculated speed difference, and the server side executes retransmission control in the MAC layer in response to this. As a result, retransmission control in a higher-layer protocol can be avoided, so that a decrease in throughput can be minimized. The fifth effect is that since the training accompanying the line quality deterioration is executed, even if the transmission speed is reduced, if the speed difference after the change is small, the current transmission speed is read and the transmission speed before the change is read. In addition to calculating the difference, the transmission buffer usage rate can be read to force a collision, and in response to this, the server executes retransmission control in the MAC layer,
As a result of avoiding retransmission control in the upper-layer protocol, the decrease in throughput can be minimized,
The buffer capacity can be minimized, and as a result, the delay time can be reduced. A sixth effect is that a forced collision can be generated only when the MAC address is detected and the own station MAC address is detected, so that communication within the LAN is not affected. The seventh effect is that the data in the transmission buffer immediately after the start of training can be rescued by constantly monitoring the line quality and stopping the transmission clock even if the transmission quality is deteriorated below a preset value. As well as being able to forcibly generate a collision, the server 101 responds accordingly to the MAC
The retransmission control is performed in the layer and the retransmission control in the upper layer protocol is not performed. As a result, a decrease in throughput can be minimized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram for explaining a variable data rate transmission device according to one embodiment of the present invention.

FIG. 2 is a network configuration diagram for explaining an embodiment of a communication network to which the variable data rate transmission device of FIG. 1 is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Server 102, A, B ... Variable data rate transmission device 103 ... Telephone 104 ... POTS 105 ... Terminal 106 ... Transmission line 107 ... Ethernet line 201 ... Physical layer processing unit 202 ... MAC layer processing unit 203 ... Reception buffer processing unit 204: transmission buffer processing unit 205: control unit 206: RADSL modem unit 207: MAC address detection unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 3/00 H04L 11/20 G 9A001 11/00 302 102A F-term (Reference) 5K030 GA03 HA08 JA09 KA03 LC01 MA04 MB01 MB15 5K033 AA01 CA08 CB06 5K034 AA05 EE11 HH01 HH02 HH21 5K051 BB02 CC01 FF12 5K101 KK20 TT06 VV01 VV04 9A001 BB03 CC02 CC06

Claims (16)

[Claims] 1. A variable data rate transmission device for minimizing a sharp decrease in communication throughput due to line quality deterioration, comprising: a RADSL modem unit whose transmission speed varies according to the line quality status; The RADSL as the current line operation state, based on the availability of the I / O, the current transmission speed, and / or the current line quality.
A control unit that reads from the modem unit, a physical layer processing unit that forcibly generates a collision in accordance with control from the control unit, a MAC layer processing unit that performs collision detection and performs frame validity confirmation, When detecting the MAC address set by the control unit, the MAC address detection unit that notifies the control unit of the detection of the own station address and the frame length to the control unit, and sequentially stores data frames from the MAC layer processing unit in a buffer. A transmission buffer processing unit for transmitting the stored data in the buffer in chronological order to the RADSL modem unit in synchronization with a clock of the RADSL modem unit; and a transmission buffer processing unit for synchronizing with the clock of the RADSL modem unit.
A variable data rate comprising a reception buffer processing unit for sequentially storing data frames from a DSL modem unit in a buffer and transmitting data stored in the buffer to the MAC layer processing unit in the chronological order of the stored time. Type transmission equipment. 2. The variable data rate transmission device according to claim 1, wherein the control unit has a function of reading a buffer usage rate of the transmission buffer processing unit. 3. The method according to claim 2, wherein the MAC address detection unit has a function of notifying the control unit of a notification of detecting the own station address and a frame length when detecting the MAC address set by the control unit. The variable data rate type transmission device according to claim 1, wherein 4. The physical layer processing unit according to claim 1, further comprising:
3. The variable data rate transmission device according to claim 1, wherein the variable data rate type transmission device has a function of terminating a physical layer of three standards and decoding received data from a received data signal. 5. The physical layer processing unit detects a collision with the MAC layer processing unit and confirms the validity of the frame, decomposes the received frame to determine a destination address, and determines whether the frame is addressed to its own station. 2. The variable data rate type transmission apparatus according to claim 1, further comprising a function of performing an error check by judging an error and transmitting a frame to the transmission buffer processing unit. 6. The RADSL modem unit according to claim 1, further comprising an ANSI modem.
T1.413 Issue 2 and ITU-TG.
992.1, ITU-TG. An RADSL modem specified in 992.2, which has a function of constantly measuring the line quality, a function of notifying the terminal device of the line quality of the own station, and an instruction of the control unit when the quality is deteriorated. 2. The variable data rate transmission device according to claim 1, wherein the variable data rate transmission device has at least one of a function of stopping a transmission clock and activating a training based on the transmission quality and setting a transmission speed according to a line quality. 7. The variable data rate transmission device according to claim 1, wherein the transmission buffer processing unit has a function of sequentially calculating a buffer usage rate. 8. When the MAC address detected by the control unit is detected from the MAC address detection unit when the line quality is degraded and data transmission at a preset quality becomes impossible. The part is the MA
The C layer processing unit is forcibly requested to generate a collision for a time corresponding to the length length, and after the request, requests the RADSL modem unit to stop transmitting the transmission clock and start training. The variable data rate type transmission device according to claim 2, wherein: 9. The control unit confirms the end of training and the transmission speed of the RADSL modem unit,
The usage rate of the transmission buffer in the transmission buffer processing unit is monitored, and when the MAC address set by the control unit is detected from the MAC address detection unit, the control unit sends a length to the MAC layer processing unit. 9. The variable data rate transmission device according to claim 2, wherein a collision is forcibly generated for a time corresponding to the length. 10. A variable data rate transmission method for minimizing an abrupt decrease in throughput of communication due to line quality deterioration, comprising: a RADSL modem step of changing a transmission speed according to a line quality situation; The availability, the current transmission rate, and / or the current line quality as the current line operation state
A control step of reading from the modem step, a physical layer processing step of forcibly generating a collision according to the control from the control step, and a MAC layer processing step of executing collision detection and frame validity confirmation. A MAC address detection step of notifying the control step of the detection of the own station address and a frame length when the MAC address set by the control step is detected, and sequentially storing data frames from the MAC layer processing step in a buffer. The data stored in the buffer is stored in the RADSL modem process in the chronologically oldest order.
A transmission buffer processing step of transmitting in synchronization with a clock of a modem step;
A variable data rate comprising a receiving buffer processing step of sequentially storing data frames from an ADSL modem step in a buffer and transmitting data stored in the buffer to the MAC layer processing step in the chronological order of the stored time. Transmission method. 11. The variable data rate transmission method according to claim 10, wherein said control step includes a step of reading a buffer usage rate in said transmission buffer processing step. 12. The MAC address detection step includes a step of, when detecting the MAC address set in the control step, notifying the control step of a notification of detecting a local station address and a frame length. The variable data rate transmission method according to claim 10. 13. The physical layer processing step may include an IEEE 80
The variable data rate transmission method according to claim 10, further comprising a step of terminating the physical layer of the 2.3 standard and a step of decoding received data from the received data signal. 14. The physical layer processing step includes the steps of: detecting a collision and confirming the validity of a frame in the MAC layer processing step; decomposing a received frame to determine a destination address; 11. The variable data rate transmission method according to claim 10, further comprising a step of determining whether or not an error has occurred and transmitting a frame to the transmission buffer processing step. 15. The RADSL modem process comprises the steps of: ANS
IT1.413 Issue 2 and ITU-T
G. FIG. 992.1, ITU-TG. A step of executing the processing steps of the RADSL modem specified in 992.2, a step of constantly measuring the line quality, a step of notifying the line apparatus of its own station to the line quality, and a case where the quality is deteriorated 11. The variable data rate according to claim 10, further comprising at least one of a step of stopping a transmission clock and starting a training based on an instruction of the control step to achieve a transmission rate according to a line quality. Transmission method. 16. The variable data rate transmission method according to claim 10, wherein said transmission buffer processing step includes a step of sequentially calculating a buffer usage rate.