JPH06261066A - System for recovering lost cell - Google Patents

Abstract

PURPOSE:To reduce information transmission delay time by reducing production of a re-transmission request due to a lost cell in the communications network of the asynchronous transfer mode. CONSTITUTION:A parity code signal generator 3 generates a parity code from each of parallel information signal from each transmission terminal equipment fed respectively via input terminals 1-1-1-3. Each of cell generators 4-1-4-4 produces cells from each parallel information signal series and a parity code signal series while including an error check redundant code corresponding to each signal series and sends the cells in parallel to an ATM communications network 3. Lost cell detection and cell composing devices 7-1-7-4 detect lost cells from the cells sent in parallel. Then a parity check device and lost cell information signal generator 9 estimates and recovers the information signal of the lost cells based on the signal series of plural cells received correctly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the concentration (congestion) of information signals (traffic) to be transmitted in the transmission of information signals using an asynchronous transfer mode (hereinafter abbreviated as "ATM") communication network. ) It relates to a lossy cell reproduction system capable of reducing the transmission delay of an information signal that sometimes occurs.

[0002]

2. Description of the Related Art In recent years, several hundred Mbp have been used by using an ATM communication network.
A high-speed computer communication capable of exchanging information at a transfer rate of s or more has attracted attention. This ATM is a system in which a transmission signal is packed in a device having a fixed number of bytes (this is called a cell) and transmitted. The input / output interface with the outside of the high-speed computer is generally a plurality of parallel information sequences, and how to efficiently transmit these in an ATM communication network is a problem. That is, in an ATM communication network, cell loss may occur due to traffic congestion at multiple nodes (switches, cross-connects, etc.) in the network or bit errors in the transmission line, so that information signals can be received stably and quickly. Need to transmit to the side.

[0003]

As a countermeasure against this, there is a retransmission control method as a method conventionally used. This re-transmission control method is used when the receiving side detects a non-arrival cell from the ATM communication network or a cell containing an error information signal (hereinafter referred to as "loss cell"), that is, during transmission. When the information is lost or erroneous, the receiving side instructs the transmitting side to retransmit the information signal, whereby the transmitting side retransmits the information signal. However, this retransmission control method has a problem that the transmission delay time of the information signal increases if the number of signals to be retransmitted increases due to cell loss. The present invention has been made in view of this problem, and an object thereof is to estimate and reproduce information of a lost cell, reduce the occurrence of a retransmission request due to the lost cell, and reduce the transmission delay time of the information. The purpose of the present invention is to provide a loss cell reproduction method that can achieve this.

[0004]

The present invention has the above-mentioned problems.
In order to solve the problem, access to the communication network of asynchronous transfer mode
Each of a plurality of parallel information signal sequences from the transmitting terminal
And obtained by parity encoding of the parallel information signal sequence
Corresponding to each signal sequence for parity signal sequence
Generate a fixed-length cell containing a redundant code for error detection
And each cell in parallel in an asynchronous transfer mode communication network.
Cell sending means for sending to
Non-arrival cells and error information from each cell transmitted in parallel
Correctly detect lost cells to detect cells containing signals
Multi-cell information signal sequence and parity signal received
From the sequence, including the non-arrival cell and error information signal
A cell reproducing means for reproducing a cell information signal.
It is characterized by.

[0005]

According to the present invention, on the transmitting side, the parallel information signal series to be transmitted and the parity signal series obtained from these signal series are individually cellized and sent to the ATM communication network, while the receiving side is provided. In this case, a lost cell is detected, and a parity check is performed on correctly received information signal sequences and parity code sequences of a plurality of cells, whereby the information signal of the lost cell is estimated and reproduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. It should be noted that, in this figure, three input terminals are provided to simplify the description. In this figure, 1-
1 to 1-3 are input terminals, 3 is a parity code signal generator, 4-1 to 4-4 are cell generators, and 5 is ATM.
Communication network, each of 7-1 to 7-4 is a lost cell detector and cell decomposer, each of 8-1 to 8-4 is a gate, 9 is a parity checker and an information signal generator of a lost cell, 10-1 -10
Each of -4 is an output terminal. Then, the transmitter 2 uses the parity code signal generator 3 and the cell generators 4-1 to 4-.
On the other hand, the receiving unit 6 includes a loss cell detecting and cell disassembling unit 7-1 to 7-4 and gates 8-1 to 8-4.
And a parity checker and an information signal generator 9 for lost cells.

In FIG. 1, information signals to be transmitted, which are supplied from three transmitting terminals (not shown), are input to the transmitting unit 2 via the input terminals 1-1 to 1-3, respectively, and a in FIG.
It is divided into two at points b, c, and one is to the parity code signal generator 3 and the other is to the cell generators 4-1 to 4-1.
4-3 respectively. Here, in FIG.
An example of the information signal sequence supplied to points a to c in FIG. 1 is shown in (c). The parity code signal generator 3 generates a code by the even (or odd) parity of the information signal sequence at the same time points a, b, and c in the figure. This even parity is "1" of the three-series information signal.
Is a method of generating a parity code "1" when the total sum is odd, while generating a parity code "0" when the total sum is even. The odd parity is a method of generating a parity code "0" when the total sum is odd and generating a parity code "1" when the total sum is even. Therefore, as shown in FIG. 2D, the information sequence at the point d in the figure is the information signal at the points a to c at that time.
It becomes "1" when the total sum of 1's is odd, while it becomes "0" when the total sum is even.

The cell generators 4-1 to 4-4 are shown in FIG.
(D) The information signal sequence is divided into predetermined block lengths, a control signal indicating the destination etc. is added to this block signal, error detection coding is performed to generate cells, and these cells are ATM It is sent to the communication network 5 in parallel.

Each cell transmitted via the ATM communication network 5 is input to the receiving unit 6. These cells are supplied to points a ', b', c ', and d'corresponding to points a to d of the transmitter in the figure. Loss cell detection and cell disassembly unit 7-1 to 7-4
Each of the input cells detects an unarrival cell and detects an error bit by decoding an error detection code signal in the cell, that is, detects a lost cell, and further controls an information signal portion of the cell. Separation from the signal part,
The clock speed conversion of the information signal portion is performed and the respective outputs are supplied to the gates 8-1 to 8-4, respectively.

By the way, the loss cell detection and cell disassembly unit 7
Each of -1 to 7-4, when a lost cell is detected,
The cell loss detection signal indicating that is supplied to the corresponding gates 8-1 to 8-4, the parity checker and the information signal generator 9 of the lost cell. Gates 8-1 to 8-4
In each of the above, loss cell detection and cell disassembly 7-
The gate is opened / closed by the cell loss detection signals from 1 to 7-4. That is, the gate is opened when it is detected that the cell is correctly received, and the gate is closed when the cell is not detected.

Information signal sequences at points e, f, g, and h of each gate output are shown in (e), (f), and (f) of FIG. 2, respectively.
Shown in (g) and (h). 2 (e) and 2 (f), the information signal sequences shown in FIG.
Alternatively, the corresponding information signal of the cell that cannot be correctly received by the receiving unit 6 due to the bit error due to the noise on the transmission line is "
These signals are supplied to the next parity checker and the information signal generator 9 of the lost cell. In the parity checker and the information signal generator 9 of the loss cell, the above even parity is used. The generated signal sequence is examined to estimate the information signal "X" of the lost cell, which is realized by the rule that the total number of "1" s is even.
Therefore, the information signal of the cell that cannot be correctly received by the receiving unit 6 is estimated and reproduced, so that the estimated information signal can be obtained at the output terminals 10-1 to 10-3.

According to this embodiment, even if a lost cell occurs, estimated reproduction of the lost cell is performed from the parity check in the correctly received cell, so that the generation of a reproduction request to the transmitting side is reduced. . If two or more lost cells occur in the parallel transmission cells transmitted at the same time, the lost cells are not regenerated.

[0013]

According to the present invention described above, on the transmitting side, the parallel information signal series to be transmitted and the parity signal series obtained from these signal series are individually cellized and sent to the ATM communication network. On the other hand, on the receiving side,
A non-arrival cell from the communication network and a lost cell including an error information signal are detected, and a parity check is performed on the correctly received information signal series and parity code series of a plurality of cells, thereby the information signal of the lost cell. Is estimated and reproduced. Therefore, it is possible to equivalently reduce the loss of the received cell in the ATM communication network, and it is possible to reduce the increase in the transmission delay time due to the retransmission due to the retransmission control.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention.

2A to 2C are respectively a to c in FIG.
6 is an example of an information signal sequence at a point, and FIGS.
Indicates an information signal sequence resulting from (a) to (c).

[Explanation of symbols]

 1-1 to 1-3 Input terminal 2 Transmitter 3 Parity code signal generator 4-1 to 4-4 Cell generator 5 ATM communication network 6 Receiver 7-1 to 7-4 Loss cell detection and cell disassembler 8 -1 to 8-4 Gate 9 Parity checker and loss cell information signal generator 10-1 to 10-3 Output terminal

Claims (1)

[Claims] 1. Each of a plurality of parallel information signal sequences from a transmission terminal accessing a communication network in an asynchronous transfer mode,
A fixed-length packet signal (hereinafter, simply referred to as a "cell") including an error detection redundant code corresponding to each of the signal sequences with respect to the parity signal sequence obtained by the parity encoding of the parallel information signal sequence. Cell transmitting means for generating and transmitting each cell in parallel to the communication network in the asynchronous transfer mode, and each cell transmitted in parallel by the cell transmitting means,
Loss cell detecting means for detecting a cell including a non-arrival cell and an error information signal, and an information signal of a cell including the non-arrival cell and an error information signal from a correctly received information signal sequence and a parity signal sequence of a plurality of cells And a cell regenerating means for regenerating the loss cell.