JPH03250834A - Method for detecting and correcting mis-delivery of missing of cell - Google Patents

Abstract

PURPOSE:To surely detect and correct all forms of cell mis-delivery, or one cell missing or plural cells missing or consecutive occurrence of them by including a reception cell error detection process and a mis-delivery detection process to the method. CONSTITUTION:A cell missing mis-delivery detection and correction circuit is provided with sequence number counters 1-3, a sequence number memory 4, a comparator 5, a cell missing number calculation computing element 6 and a dummy cell production/cell abort switch section 7. The circuit is provided with a reception cell error detection process detecting an error of a received cell and a mis-delivery detection process comparing a sequence number of the cell received at present with the value decrementing one from the count of the sequence number counters 1-3, detecting the mis-delivery of cells depending on the coincidence and detecting a missing cell depending on the dissidence. Thus, all forms of cell mis-delivery, or one cell missing or plural cells missing or consecutive occurrence of them are surely detected and corrected.

Description

[Detailed Description of the Invention] [Summary] Regarding the detection and correction method for cell omission and erroneous delivery in the asynchronous transfer mode in a wideband I5DN network, all forms of cell erroneous delivery, single cell omission, multiple cell omission, and their The purpose of this system is to reliably detect and correct consecutive occurrences.The transmitting side attaches a sequence number to the cells and transmits them, and the receiving side sequentially updates the count value of the sequence number counter and checks the sequence of the received cells. In the method of detecting missing cells and erroneous delivery by comparing the number with the count value of the sequence number counter, the sequence number of the previous received cell is compared with the value obtained by subtracting 1 from the count value of the sequence number counter. Then, when a received cell error detection process detects a received cell error based on the mismatch, and a received cell error detection process detects a received cell error, 1 is decremented from the sequence number of the currently received cell and the count value of the sequence number counter. The method includes a erroneous delivery detection step of comparing the subtracted value and detecting erroneous delivery of a cell based on a match, and detecting a missing cell based on a mismatch.

[Industrial Application Field] The present invention relates to a method for detecting and correcting asynchronous transfer mode (ATM) cell dropout and erroneous delivery in a broadband ISDN network.

Broadband I5DN is being researched and developed as a next-generation communication network that integrates various communication services such as voice, video, and data. Asynchronous transfer mode converts all of that information into fixed-length blocks called cells and transfers it at high speed, regardless of the generation status or communication speed of continuous information such as audio and video images, or burst information such as data. It's technology.

When transmitting continuous information such as audio and video images using this asynchronous transfer mode, there is a risk that cells may be lost due to tilting in the asynchronous transfer mode network, or cells may be mis-delivered due to cell head errors. Therefore, there is a need for a function that can detect and correct these cell omissions and erroneous deliveries.

[Prior art] As a method for detecting and correcting missing cells and erroneous delivery, the sending side adds consecutive sequence numbers to the cells and transmits them, and the receiving side detects errors based on the sequence numbers of the cells sent. There is a way to do it.

FIG. 8 shows a schematic configuration of such a system for detecting and correcting missing cells and erroneous delivery.

In FIG. 8, 51 is a transmitter as an information source, 52 is a transmitter, 53 is a communication network, 54 is a receiver, and 55 is a receiver. Here, the transmitting section 52 includes a data dividing section 41 and a sequence number adding section 42. Further, the receiving section 54 includes a user data extracting section 43 and a user data buffer 44.
, sequence number extraction unit 45. Missing cell erroneous delivery detection and control section 46, dummy cell generation section 47, cell discard switch section 48. It is configured to include a fluctuation absorption buffer 49 and the like.

The operation of this missing cell erroneous delivery detection and correction system will be explained below.

First, on the transmitting side, continuous information of an arbitrary data length sent from the transmitter 51 as an information source is divided into fixed length user data cells in the data dividing section 41, and the sequence number adding section 42 divides the continuous information of arbitrary data length into user data cells. Continuous sequence numbers are sequentially added to the data and sent to the receiving side via the communication network 53.

The frame format of this user data cell is shown in FIG. 9, and as shown, the cell consists of a header field and an information field, within which a sequence number SN (n) is assigned. This sequence number is an integer from 1 to the maximum value N.
The sequence numbers up to 1 are used repeatedly and assigned to cells. Also, the sequence number of the nth cell is SN (n)
It shall be expressed as .

On the receiving side, the information cell sent from the communication network 53 is sent to a user data extraction unit 43 and a sequence number extraction unit 45.
to be distributed. The user data retrieval unit 43 deletes only the sequence number of the information cell, converts it into pure user data, and sends it to the user data buffer 44, where it is stored.

On the other hand, the sequence number extraction section 45 extracts the sequence number from the information cell and passes this sequence number to the cell omission/erroneous delivery detection and control section 46.

The cell dropout and erroneous delivery detection and control unit 46 detects a cell dropout or cell erroneous delivery based on information such as this sequence number, and in the case of a cell dropout, detects the cell dropout in the data from the user data buffer 44. A dummy cell generated by the dummy cell generation unit 47 is inserted into the part, and on the other hand,
In the case of erroneous cell delivery, the erroneously delivered cell part in the data from the user data buffer 44 is discarded by the cell discard switch section 48, and cells are reproduced and discarded for the received cell string, and the fluctuation absorbing buffer is then discarded. 49 to the receiver 55.

Conventionally, as a method of configuring the missing cell erroneous delivery detection and control section 46, etc. in this cell missing erroneous delivery detection and correction system,
For example, there are two methods as follows.

References below: Bruce B, Kittan+s, “C1rcui
t Emulation Performance wi
th DSI and DS3 and Example
es.

in Tl51. l/88-414. ,0ctober
This is the method described in 1988. In this method, a sequence number counter is prepared on the receiving side,
The count value SNC of this sequence number counter is sequentially incremented so as to correspond to the sequence numbers of cells sequentially received during normal operation, and thereby the cell numbers of the received cells and the count value SNC of the sequence number counter are sequentially incremented. They are compared, and if they match, it is determined that the cell with that number was sent correctly without an error.

On the other hand, if there is a mismatch, it is determined that an error such as a missing cell or erroneous delivery has occurred.

FIG. 10 shows a process for detecting and correcting missing cell mis-delivery (corresponding to the process performed by the missing cell mis-delivery detection and control section 46, dummy cell generation section 47, and cell discard switch section 48 in FIG. 8). Processing steps are shown. In the figure, SN (n
), SN (n+1) are the n-th and n+
Let SNC represent the sequence number of the first cell, and SNC represent the current count value of the sequence number counter.

The method shown in FIG. 10 uses two sequence numbers SN (
n), SN (n+1>) and the count value SNC of the sequence number counter using four judgment conditions.
This detects and corrects missing cells and erroneous delivery of one cell.

In FIG. 10, first, the sequence number SN (n) of the received cell and the count value S of the sequence number counter
If the judgment conditions i) match in step S2, the sent cell is judged to be correct, and the count value SNC of the sequence number counter is set to 1.
is added (step 530), and subsequent checks are continued for other cells (step 531).

On the other hand, if there is a mismatch, it is determined that an error has occurred in the received cell, such as missing cells or misdelivery.

If an error is determined, compare the sequence number SN (n) of the currently received cell with the value SNC + 1, which is the count value of the sequence number counter plus 1. Determine whether there is a missing cell or an incorrect delivery. If the comparison results match, it can be determined that a cell is missing, while if they do not match, it can be determined that erroneous delivery has occurred.

If it is determined that a cell is missing, the sequence number SN (n+1) of the next received cell and the count value of the sequence number counter plus 2 (SNC+2) are added.
Step S23
: If the judgment condition 1ii) matches, it is judged that 1 cell is missing, and one dummy cell is inserted in the position of the missing cell.Step 524), and 3 is added to the count value SNC of the sequence number counter (Step 524). 525), and the check continues (step 531).

On the other hand, if they do not match, 2 is added to the count value SNC of the sequence number counter (step 526) and the check is continued (step 531).

In addition, if it is determined that an erroneous delivery has occurred, it is determined whether or not one cell is erroneously delivered by comparing the sequence number 5N (n+1) of the next received cell with the count value SNC of the sequence number counter. (Step S27: Judgment examination iv). If they match, it is determined that one cell has been misdelivered, and the misdelivered cell is discarded (step 328), 1 is added to the count value SNC of the sequence number counter (step 529), and the check is continued (step 529). 531)
. If they do not match, 2 is added to the count value SNC of the sequence number counter (step 526), and the check is continued (step 531).

As described above, if one cell is missing or one cell is mis-delivered in the series of received cells, this can be detected and corrected.

Another method for detecting and correcting cell omission and erroneous delivery is, for example, the method described in Japanese Patent Laid-Open No. 192289/1999. This method uses two sequence numbers SN (n),
The difference is calculated based on the value of SN (n+1), and using a preset threshold, if the difference is 1, the arriving packet is accepted, and if it is 2 or more, it is accepted as [SN (n+1)].
) 5N(n) -1+wod N] pseudo packets are inserted, and if the difference between them is greater than O or the maximum value N of the sequence number, the arriving packet is discarded.

[Problems to be Solved by the Invention] The former cell missing and erroneous delivery detection and correction process shown in FIG. 10 has the following problems.

■If the sequence number of the incorrectly delivered cell is one larger than the current count value SNC of the sequence number counter,
For example, if the cell with sequence number 5 is mis-delivered as shown in FIG. 11, this cannot be detected. That is, in such a case, in step S21, false,
It is false in step s22, false in step S27, and cannot be detected.

■It is not possible to remove cells (it is not possible to deal with cases where multiple cells are removed at once).

■ll If cell omission or multiple cell omission occurs two or more times in a row, for example, as shown in Figure 12,
If the cells with sequence numbers 5 and 7.9 each do not have one cell missing, this cannot be detected or corrected.

Furthermore, the latter method of detecting and correcting cell omission and erroneous delivery has the problem that when erroneous cell delivery occurs, a large amount of necessary cells are also discarded.

The present invention was made in view of the above circumstances, and its purpose is to eliminate all forms of cell mis-delivery,
Another object of the present invention is to provide a cell omission erroneous delivery detection and correction method that can reliably detect and correct one cell omission, multiple cell omissions, and their consecutive occurrences.

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

In one form of the cell omission erroneous delivery detection method according to the present invention, the transmitting side attaches a sequence number to the cell and transmits it, and the receiving side sequentially updates the count value of a sequence number counter while receiving the received cell. In the method of detecting missing cells and erroneous delivery by comparing the sequence number of the previous cell with the count value of the sequence number counter, A reception cell error detection process SL compares the value 5NC-1 obtained by subtracting 1 and detects an error in the reception cell based on the discrepancy, and when an error in the reception cell is detected in the reception cell error detection process, Erroneous delivery detection step S2 which compares the sequence number SN (n) and the value 5NC-1 obtained by subtracting 1 from the count value of the sequence number counter, detects erroneous delivery of a cell based on a match, and detects a missing cell based on non-defeat. It includes.

As another form of the cell missing erroneous delivery detection method according to the present invention, in the above-mentioned form, when a cell missing is detected in the erroneous delivery detection process, the sequence number of the previously received cell is 5N (n-1). ) and the count value SNC of the sequence number counter, and if they match, one cell omission is detected,
The process further includes a cell missing detection step S5 of detecting a plurality of missing cells based on the mismatch.

In still another embodiment of the cell missing erroneous delivery detection method according to the present invention, in the above-mentioned form, in the cell missing detection process, one
When a cell dropout is detected, the sequence number SN (n) of the currently received cell is compared with the value SNC+1, which is the count value of the sequence number counter plus 1, and if they match, the isolated occurrence of one cell dropout is detected. Then, based on the mismatch, continuous occurrence of one cell dropout is detected in l cell dropout single/continuous detection step S6, and when multiple cell dropouts are detected in the cell dropout detection step, the sequence number of the previously received cell is detected. The value 5N (n-1) + 1 added by 1 is compared with the currently received cell sequence SN (n), and if they match, an individual occurrence of multiple cell omissions is detected, and if they do not match, multiple cell omissions occur consecutively. The method further includes a multiple cell omission individual/continuous detection process Sll for detecting a plurality of missing cells.

The cell dropout misdelivery detection and correction method according to the present invention includes, in each of the above embodiments, a misdelivery cell discard step S3 for discarding a misdelivery cell in response to a cell misdelivery; The method further includes dummy cell insertion steps S7, S9, Si2, and S14 for inserting dummy cells at the positions.

[Operation: In the received cell error detection process S1, the sequence number 5N(n-1) of the previous received cell is compared with the value 5NC-1 obtained by subtracting 1 from the count value of the sequence number counter (step S12). Judgment condition engineering). If these match, it can be determined that there was no error in the received cell, in which case the SNC of the sequence number counter is incremented by one (step 516) and the check is continued (step 517).

On the other hand, if the comparison results do not match, it can be determined that an error such as erroneous delivery or missing cells has occurred. In this case, first, in the erroneous delivery detection step S2, it is detected whether or not erroneous cell delivery has occurred. This includes the sequence number 5N (n-1) of the previous cell received and the value 5NC-1, which is the count value of the sequence number counter minus 1.
(Step S2: Condition ■). As a result of this comparison, if they match, it can be determined that the error is erroneous cell delivery.

Now, for example, as shown in FIG.
It is assumed that a cell with sequence number 8 is erroneously delivered between cells 5 and 5. In this case, if the cell with sequence number 5 is the currently received cell, the cell number 5 of the currently received cell is
Since the value 5 obtained by subtracting 1 from the count value 6 of the sequence number counter at that time matches, it can be determined that the previously received cell with the sequence number 8 has been misdelivered.

When it is determined that the delivery was incorrect, the sequence number 5N (
In step S3), the count value of the sequence number counter is incremented by one to discard the cell n-1).
In step S4), the check is continued.

On the other hand, when it is determined in the erroneous delivery detection step S2 that there is no mismatch, it can be determined that a cell omission has occurred. This cell dropout includes one cell dropout, multiple cell dropout, and cases where these occur singly or consecutively, and these are detected by the following procedure.

First, in the cell dropout detection process S5, it is determined whether the cell dropout is one cell dropout or multiple cell dropouts (step S5 second determination condition (2)). To do this, the sequence number 5N (n-1') of the previous cell received is compared with the count value SNC of the sequence number counter. If they match, one cell is dropped, and if they do not match, multiple cells are dropped. It can be determined that it is missing.

Now, for example, as shown in FIG.
Assume that one cell is missing between cells 6 and 6, that is, the cell with sequence number 5. In this case, if the cell with sequence number 7 is the currently received cell, the sequence number 6 of the previously received cell and the count value 6 of the sequence number counter match, so it can be determined that one cell is missing. .

On the other hand 1, for example, as shown in FIG. 4, three cells between sequence numbers 4 and 8, i.e.
If the cell number 7 is missing multiple cells, if the sequence number of the currently received cell is 9, the sequence number 8 of the previously received cell and the count value 6 of the sequence number counter do not match, so It can be determined that multiple cells are missing.

If it is determined that one cell is missing in the cell missing detection process S5, then in the one cell missing individual/continuous detection process S6, the l
It is determined whether the cell omission has occurred only once or continuously. This includes the sequence number SN (n) of the currently received cell and the value SNC+1, which is the count value of the sequence number counter plus 1.
(Step S6: Judgment condition IV). As a result of this comparison, if they match, it is a single occurrence, and if they do not match, it is a continuous occurrence.

For example, in the case of Figure 2, the sequence number 7 of the currently received cell is 1 to the count value 6 of the sequence number counter.
Since it matches the value 7 which is the sum of

On the other hand, in the case of FIG. 5, for example, the cells between sequence numbers 4 and 6 and between sequence numbers 6 and 8 are each 1
Although a cell is missing, the sequence number 8 of the currently received cell does not match the value 7 obtained by adding 1 to the count value 6 of the sequence number counter, so it can be determined that one cell is missing continuously.

If one cell omission occurs alone, a dummy cell is inserted at the position corresponding to the cell with sequence number SN (SNC-1) (step S7), and the count value SNC of the sequence number counter is incremented by +3 (step S7). S8), continue checking.

On the other hand, if one cell omission occurs continuously, a dummy cell is inserted at the position corresponding to the cell with sequence number SN (SNC-1) (step S9), and the count value SNC of the sequence number counter is incremented by +2. (Step 510), and the check continues.

Further, when it is determined that multiple cells are missing in the cell missing detection process S5, whether the multiple cells missing occurs singly or consecutively is determined in the multiple cell missing & 1 single/continuous detection process Sll. To do this, compare the value 5N(n-1)+1, which is the sequence number of the previous cell received plus 1, with the sequence number SN (n) of the currently received cell (Step Sll: Judgment condition ■) . As a result of the comparison, if there are seven matches, it is a single occurrence, and if there are no matches, it is a consecutive occurrence.

For example, in the case of Figure 4 mentioned above, it is a single occurrence, but if the cell with sequence number 9 is the currently received cell, the value 9, which is the sequence number 8 of the previously received cell plus 1, is the currently received cell. Since it matches cell sequence number 9,
Multiple cell omissions can be determined to be a single occurrence.

On the other hand, for example, FIG. 6 shows the continuous occurrence of multiple missing cells, with three missing cells between sequence numbers 4 and 8, and three missing cells between sequence numbers 8 and 12. However, in this case, if the cell with sequence number 12 is the currently received cell, the value 9, which is the sequence number 8 of the previous received cell plus 1, matches the sequence number 12 of the currently received cell. Therefore, it can be determined that multiple cell omissions occur continuously.

If it is determined that a single missing multiple cell has occurred, the number 514). Here, N is the maximum value of the sequence number, and sod represents mode calculation.

After inserting the dummy cell, the count value SNC of the sequence number counter is incremented by (X+1) (step 515), and the check is continued.

Similarly, if it is determined that multiple cells are missing consecutively,
In order to insert X dummy cells determined by the above calculation formula into the missing cell portion, step 512) increment the count value SNC of the sequence number counter by X (step 313) and continue checking.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 7 shows a circuit for performing a method for detecting and correcting cell omission and erroneous delivery as an embodiment of the present invention.

This embodiment circuit is a circuit corresponding to the circuit portions of the cell omission/misdelivery detection and control section 46, dummy cell generation section 47, and cell discard switch section 48 in FIG. It is for carrying out.

In FIG. 7, 1.2.3 is a sequence number counter, sequence number counter 2 outputs the current count value SNC, and sequence number counter 1 outputs the current count value SN,C minus 1, 5NC. -1 is output, and sequence number counter 3 is set to the current count value SNC.
Outputs the value SNC+1, which is the sum of 1 and 1. The outputs of the sequence number counters 1 to 3 are input to the comparator 5, and the output SNC from the sequence number counter 2 is input to the cell omission number calculation unit 6.

4 is a sequence number memory, into which the sequence number SN (n) extracted from the currently received cell by the sequence number extraction unit 45 is input, and by holding this, the sequence number 5N ( of the previously received cell) is inputted. n-1) and the sequence number 5N(n
-1) plus 1 to generate a value 5N(n-1)+1, and send these to the comparator 5.

The comparator 4 performs steps S1, S2, and S2 in FIG.
This is a circuit that performs judgments on the judgment conditions ■ to V in S5, S6, and Sll based on each input signal, and it can be realized in software using a microcomputer, etc., or it can be realized in a hardware circuit that performs logical operations. It can also be achieved.

The cell omission number calculation unit 6 is the sequence number extraction unit 4.
Sequence number SN (n) from 5 and count value SNC from sequence number counter 2 are input,
Based on this, the following formula % formula % is calculated. Here, N is the maximum value of sequence numbers. This calculation result X is output to the dummy cell generation/cell discard switch section 7.

In addition to the calculation result X, the dummy cell generation/cell discard switch section 7 is inputted with the judgment result signal from the comparator 5 and the user data from the user data buffer 44, so that the cell missing portion of the user data string is The user data string is corrected by inserting dummy data and discarding the erroneously delivered data, and the resulting user data is output to the receiver 55.

For the operation of this embodiment circuit, reference can be made to what has been explained with reference to FIG. That is, the comparator 5 receives each input signal, i.e. each count value 5NC-1 of the sequence number counter.
, SNC, SNC+1, sequence numbers of the current and previously received cells SN (n), SN (n-1)
Based on the value 5N(n-1)+1, the judgment conditions ■ to V shown in FIG. If it is an incorrect delivery or a missing cell, or if a cell is missing,
It is determined whether the cell omission is one cell omission or a plurality of cells omission, or whether the cell omission occurs singly or consecutively, and the determination result signal is transmitted to the dummy cell generation/cell discard switch section 7.

As a result, the dummy cell generation/cell discard switch section 7 transmits the user data from the user data buffer 44 to the receiver 55 as is if there is no error in the received cell. On the other hand, if it is determined that there is an erroneous delivery, the data in the erroneously delivered cell portion of the user data from the user data buffer 44 is discarded, and if it is determined that a cell is missing, the user data from the user data buffer 44 is discarded. Dummy data is inserted into the data of the missing cell portion and is transmitted to the receiver 55. In the case of a plurality of missing cells, the number X of missing cells is given by the cell missing number calculation unit 6, and dummy data corresponding to that number is inserted.

[Effects of the Invention] As explained above, according to the present invention, all erroneously delivered cells including erroneously delivered cells having a sequence number one larger than the count value of the sequence number counter can be detected.
In addition, it is possible to reliably detect not only one cell missing, but also one cell missing, multiple cells missing, and the consecutive occurrence of these, and the data can be discarded or discarded for these erroneous deliveries and data with missing cells. By inserting dummy data, error data can be corrected.

This makes it possible to minimize the deterioration in service quality caused by cell dropout and erroneous delivery, which greatly contributes to improving the reliability of such ATM networks.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a diagram explaining detection of one cell mis-delivery, and Fig. 3 is a diagram explaining the principle of the present invention.
Figure 4 is a diagram explaining the detection of missing cells, Figure 4 is a diagram explaining the detection of multiple missing cells, Figure 5 is a diagram explaining the detection of consecutive occurrences of missing cells, and Figure 6 is a diagram explaining the consecutive occurrence of multiple missing cells. FIG. 7 is a diagram illustrating a circuit for detecting and correcting missing cell mis-delivery as an embodiment of the present invention, and FIG. 8 shows a schematic configuration of a missing-cell mis-delivery detection and correction processing system. FIG. 9 is a diagram illustrating a cell frame format. Fig. 10 is a flowchart showing a conventional cell missing erroneous delivery detection and correction procedure, Fig. 11 is a diagram showing an example of erroneous cell delivery, and Fig. 12 is a diagram showing an example of multiple consecutive missing cells. be. In the figure, 1 to 3...-Sequence number counter 4...Sequence number memory 5...Comparator 6...-Cell dropout number calculation calculator 7...-Dummy cell generation/cell discard switch section 41...
・Data division unit 42...Sequence number addition unit 43...User data extraction unit 44...User data buffer 45...Sequence number extraction unit 46...Cell omission/erroneous delivery detection and control unit 47...・Dummy cell generation unit 48...Cell discard switch unit 49...Fluctuation absorption buffer 51...Transmitter 52...Transmission unit 53...Communication network 54...Reception unit 55-...Receiver unit ( 5 5NC-I SNCSrC 1 11? Le board 1y 71 consecutive results, and the treatment of Enoki is shown in Figure 6. Sent, Homaru Dej Maru also correction system tree scolding structure structure ``ヾ

Claims (1)

[Claims] 1. On the transmitting side, a sequence number is attached to the cell and transmitted,
On the receiving side, the count value of the sequence number counter is sequentially updated, and the sequence number of the received cell is compared with the count value of the sequence number counter, thereby detecting missing cells and erroneous delivery. The sequence number of the received cell [SN(n-1
)] and a value obtained by subtracting 1 from the count value of a sequence number counter [SNC-1], and a receiving cell error detection step (step S1) of detecting a receiving cell error based on the mismatch; and the receiving cell error detecting step. When an error is detected in the received cell, the sequence number [SN(
n)] is compared with the value [SNC-1] obtained by subtracting 1 from the count value of the sequence number counter, and a misdelivery detection process (step S2) A cell omission erroneous delivery detection method. 2. When a missing cell is detected in the erroneous delivery detection process, the sequence number of the previous received cell [SN(n-1)]
A cell missing detection process (step S
5) The method for detecting cell omission and erroneous delivery according to claim 1, further comprising: 5). 3. When one cell is detected in the cell missing detection process,
The value obtained by adding 1 to the sequence number [SN(n)] of the currently received cell and the count value of the sequence number counter [
SNC+1], detecting the single occurrence of one cell omission based on the coincidence, and detecting the continuous occurrence of one cell omission based on the mismatch (step S6); When multiple cells are detected in the process,
The sequence number of the previously received cell plus 1 [SN(n-1)+1] is compared with the sequence number of the currently received cell [SN(n)], and if they match, multiple cells are dropped. 3. The cell missing erroneous delivery detection method according to claim 2, further comprising a multiple cell missing individual/consecutive detection step (step S11) of detecting the single occurrence of multiple cell missing and detecting the consecutive occurrence of multiple cell missing based on the mismatch. 4. An erroneously delivered cell discarding process (step S3) in which the erroneously delivered cell is discarded in response to an erroneous cell delivery; and a dummy cell insertion process in which a dummy cell is inserted in the position of the missing cell in response to a missing cell (steps S7 and S9). ,S1
2. The cell omission erroneous delivery detection and correction method according to any one of claims 1 to 3, further comprising: 2.S14).