JPH03179851A - Transfer system for cell provided with delay fluctuation absorption - Google Patents

Abstract

PURPOSE:To improve the data reception quality by activating a delay fluctuation absorbing capability missing prevention function again every time the missing of consecutive reception cell string takes place so as to suppress production of momentary interruption caused in an expanded data string thereby keeping the normal expansion to the expanded data string of a reception cell after the reception cell string. CONSTITUTION:Identification information representing the presence of loss of cell consecution in a received cell string is outputted from an identification information output section 14 for each cell and its identification information is stored in a storage section 16 together with the data information from a cell decomposing section 10. When read identification information represents cell consecution loss information at the readout of the storage section 16 by a readout control section 18, fluctuation absorption delay is given to the readout information from the storage section 16 the same as the output of head identification information from the identification information output section 14. Thus, the loss of the delay fluctuation absorption capability is prevented, the delay fluctuation absorbing capability is continued and the missing of data is prevented.

Description

[Detailed Description of the Invention] (Summary) Regarding a cell transfer method with fluctuation absorption delay that adds a fluctuation absorption delay when reading the first cell in a received cell string or when cell continuity is lost, the present invention relates to a cell transfer method that adds fluctuation absorption delay when reading the first cell in a received cell string or when cell continuity is lost. A cell decomposition unit that extracts data information in each cell in a received cell string and location information of the cell in order to prevent data loss, and data that identifies leading data information in response to the location information. a column head detection section, an identification information output section that outputs identification information indicating the presence or absence of cell continuity loss in the data string being received in response to the position information, and data information output from the cell disassembly section and a storage unit that receives identification information corresponding to the data information outputted from the identification information output unit and saves and stores the input order of each piece of information; and a readout control unit that controls reading of the storage unit. and the read control unit controls reading from the storage unit when the head identification information is output from the identification information output unit or when identification information serving as cell continuity loss information is read from the storage unit. The structure was designed to provide a delay in absorption of fluctuations.

[Industrial Application Field] The present invention relates to a cell transfer system that adds a fluctuation absorption delay when reading a leading cell in a received cell string or when cell continuity is lost.

Conventional packet switching systems are suitable for accommodating and exchanging various types of information because they can freely set the packets that they want to transmit using the time slots formed on the transmission path. Because it is an exchange system, it is not suitable for communications that require very high communication speeds, such as image communications. ATM (
Asynchronous Transfer Mod
e) The communication method is broadband IS, which is the future communication network.
D N (Integrated Service
It is seen as a promising candidate for a communication system for building a D1G1TAL Network. This ATM communication system also has the following problems to be solved.

[Conventional technology]

In the ATV communication system as described above, information cells are assembled on the transmitting side, and cells are disassembled on the receiving side.

ATMs like this! When attempting to transfer information such as audio or moving images under a communication system, while the information is being continuously generated on the transmitting side, the transmitting side is transmitting cells (cells) sent almost periodically. (see Figure 6), if there is no fluctuation in the transfer delay that occurs within the ATM network, the receiving side can receive the cell almost periodically (see (a) in Figure 5).
(1)), even if the data string is expanded as it is, no instantaneous data interruption will occur in the expanded data string (see (2) of (a) in FIG. 4).

However, when fluctuations in transfer delay occur within an ATM network, the fluctuations in transfer delay are applied to cells sent out on the transmitting side and sent to the receiving side via the ATM network. Then, even if the transmitting side sends cells almost periodically, the cells received at the receiving side will not be periodic (
(See (1) in (b) of Figure 4). If we expand such a received cell string as it is into a data string, we get ((b) in Figure 4).
As shown in 2), a momentary data interruption occurs in the expanded data string. This causes noise in voice communication and image disturbance in image communication.

A technical means for absorbing delay fluctuations as described above has already been developed, and as shown in FIG. It is configured by providing a version information analysis section 26 and a readout control section 30. The cell decomposition section 10 includes a user information extraction section 22 and an adaptation information extraction section 24. The cell disassembly section 10
A user information extracting section 22 extracts user information (see FIG. 6) from the cell string received at the cell string, and an adaptation information extracting section 24 extracts position information for each cell in the cell string.

The first cell in the cell string is detected by the adversion information analysis section 26 that responds to the cell position information. In response to the detection of the first cell in the received cell string, the readout control section 30 reads cells from a time delayed by the delay fluctuation absorption time, thereby absorbing the aforementioned delay fluctuation. The delay time for absorbing delay fluctuation is
It is determined by the aforementioned delay fluctuation given to the cell by ATMm.

By doing so, the occurrence of the instantaneous interruption described above can be suppressed (see (1) and (2) in (a) of FIG. 7).

[Problem to be solved by the invention]

However, if cells are discarded in the received cell string (see (1) in (b) of FIG. 7), it is not possible to absorb delay fluctuations even with the conventional means described above. If this is not possible, data will be missing as shown in (2) of (b) in FIG. 7). This also causes the same problem as when there is no means for absorbing delay fluctuations.

The present invention was created in view of such problems, and an object of the present invention is to provide a fluctuation-absorbing delay-adding cell transfer method that can prevent data loss even if cells are discarded. .

[Means for Solving the Problems] FIG. 1 shows a block diagram of the principle of the present invention. As shown in this figure, the present invention includes a cell disassembly unit 10 that extracts data information in each cell in a received cell string and location information of the cell, and identifies leading data information in response to the location information. a data string head detection section 12; an identification information output section 14 that outputs identification information indicating the presence or absence of cell continuity loss in the data string being received in response to the position information; and the cell disassembly section 10.
The data information output from and the identification information output unit 14
A storage unit 1 that receives identification information corresponding to the data information output from the storage unit 1 and stores the input order of each piece of information.
6 and a read control unit 18 that controls reading of the storage unit 16, and the read control unit 1
8 is for reading from the storage unit 16 when the head identification information is output from the identification information output unit 14 or when identification information indicating cell continuity loss information is read from the storage unit 16. The present invention is configured to provide fluctuation absorption delay.

[For production]

Identification information indicating the presence or absence of cell continuity loss in the received cell string is output from the identification information output unit 4 for each cell,
The identification information is stored in the storage section 16 together with the data information from the cell disassembly section 10.

When the readout control unit 18 reads out the storage unit 16, when the readout identification information indicates cell continuity loss information, the identification information output unit 14 outputs the leading identification information in response to the readout from the storage unit 16. Same as when
The fluctuation absorption delay is applied to prevent the loss of the delayed fluctuation absorption ability, and the delayed fluctuation absorption ability is maintained.

〔Example〕

FIG. 2 shows an embodiment of the invention. In this figure, a cell discard detection section 32 (corresponding to the identification information output section 14 in FIG. 1) is added to the components shown in FIG. 5. The cell discard detection section 32 receives the sequential number in the position information within the data string outputted from the adaptation information extraction section 24 and outputs cell discard information. Cell discard information from the cell discard detection unit 32 is supplied to the PIF 028 (corresponding to the storage unit 16 in FIG. 1). The readout control unit 38 (corresponding to the readout control unit 18 in FIG.
corresponds to ) and data string head information from PIF02
The PIF 028 is configured to control readout of the PIF 028 in response to cell discard information from the PIF 028. Cell discard detection section 32
is the sequential number storage unit 34 and the difference calculation unit 36
Consists of. The sequential number storage unit 34 extracts the sequential number one cell before. The cell discard detection unit 32 outputs cell discard information from the sequential number of the human-powered cell and the sequential number of the previous cell. Among the components shown in FIG. 2, the same components as those shown in FIG. 5 are given reference numerals, and a description of the components will be omitted.

The operation of the present invention configured as described above will be explained below.

When delay fluctuation is given to the received cell string input to the cell disassembly unit 10 via the ATM network, but there is no condition causing cell discard in the cell transfer network, the processing for the received cells is as follows in the fifth step. There is no difference from what was explained in the figure. The function of the cell discard detection section 32 in the above state does not have any effect on the above-described processing for the received cell. That is, the sequential number of the input cell in the difference calculation unit 36 and 1
This is because the difference value (cell discard information) from the sequential number before the cell is l. This is because even if this 1 is written to PIF 028 together with the user information of the corresponding cell in FIFO 28 and then read out, there is no change in the user information reading operation in PIF 028.

However, when the difference value becomes a value other than 1 (the third
(See (1) in the figure), the value is written to PIF028 together with user information equivalent data (invalid data) of the corresponding cell, and the difference value of the read value other than l is used to discard the cell in the cell transfer network. This means that the difference between the values other than 1 is PIF0.
When the data corresponding to the cell user information is read from PIF 028, a fluctuation absorption delay is applied to the reading when the user information next to the data corresponding to the cell user information is read from PIF 028 (the third
(See (2) in the figure). The process of the present invention prevents the loss of the conventional delay fluctuation absorbing ability, which is effective until a cell is discarded.

Therefore, it is possible to suppress the occurrence of instantaneous interruptions that occur in the expanded data string,
The received cells subsequent to that cell can be normally expanded into an expanded data string. This helps prevent deterioration in the reception quality of data transferred on each cell.

Although the above embodiment deals with the case of cell discard, the present invention can be applied to a case where no cell discard occurs but a cell continuity loss state occurs in the received cell string. , nothing is lost.

[Effect of the invention] As is clear from the above description, according to the present invention,
Every time the continuity of the received cell string is lost, the delay fluctuation absorption ability loss prevention function is activated again, so that it is possible to suppress the occurrence of momentary interruptions that occur in the expanded data string, and the expanded data string of the received cells after that cell can be suppressed. It is possible to maintain the normal development of data and improve the quality of data reception.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a diagram showing an embodiment of the present invention, Fig. 3 is a diagram explaining the advantages of the present invention, and Fig. 4 is a diagram showing the cell transfer method that occurs in conventional ATV communication. FIG. 5 is a diagram illustrating a conventional fluctuation-absorbing delay-adding cell transfer system. FIG. 6 is a diagram showing a cell format. FIG. 7 is a diagram illustrating a drawback occurring in a conventional fluctuation-absorbing delay-adding cell transfer system. In FIGS. 1 and 2, 10 is a cell decomposition unit, 12 is a data string head detection unit (adaptation information analysis unit 26), 14 is an identification information output unit (cell discard detection unit 32), and 16 is a storage unit. (PIF02B), 18 is a read control unit (read control unit 38). 4 Jyugyokuri Book Map for March, Figure 1

Claims (1)

[Claims] (1) A cell disassembly unit (10) that extracts data information in each cell in a received cell string and position information of the cell; and a data string head detection unit (10) that identifies the head data information in response to the position information. 12); an identification information output unit (14) that outputs identification information indicating whether or not there is a loss of cell continuity in the data string being received in response to the position information; a storage unit (16) that receives data information corresponding to the data information and identification information outputted from the identification information output unit (14), and saves and stores the input order of both pieces of information; (16); and a readout control unit (18) for controlling readout of the identification information output unit (16).
When the leading identification information is output from 4) or when the identification information indicating cell continuity loss information is read from the storage section (16), there is a fluctuation absorption delay with respect to reading from the storage section (16). A fluctuation-absorbing delay-imparting cell transfer method characterized by providing the following.