JPH11215192A - Variable length packet communication method and packet communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to divide a packet into small packets and to retransmit them even when error correction of an automatic repeat request(ARQ) of a selective repeat(SR) system is performed by providing the packet with a retransmission identification flag and setting a sub transmission order number in a retransmission packet. SOLUTION: In executing ARQ error correction of an SR system, a communication packet at the time of normal communication consists of an opening flag, an ending flag, a transmission order number, a retransmission identification flag, data and a CRC error detection code. The communication packet at the time of retransmission consists of the opening flag, the ending flag, the transmission order number, the retransmission identification flag, a sub transmission order number, a retransmission completion flag, the data and the CRC error detection code. That is, a packet is provided with the retransmission identification flag, the retransmission packet is provided with the sub transmission order number so that it is divided into smaller packets by the same order number and can be retransmitted, and the retransmission packet completion flag is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable length packet communication method and a packet communication device effective in a wireless communication network in which an error rate changes every moment like a mobile communication network.

[0002]

2. Description of the Related Art In recent years, second generation mobile communication systems featuring digital communication have been rapidly spreading. For example, PHS (Personal Handy Phone System) is a TDMA / TDD (Time
(Division Multiplex Access / Time Division Duplex) system and 32 kbps transmission capacity in one slot, so it can transmit not only voice, data and still image but also video. It is greatly expected as an infrastructure to be realized.

The ARQ (Automatic Repeater) of the conventional SR system
t Request) An error correction method will be described with reference to the drawings.
FIG. 7 is a diagram showing a conventional packet configuration at the time of normal transmission and a packet configuration at the time of retransmission. Fig. 8 shows GBN (Go Back N)
FIG. 3 is a diagram showing a data flow between a data transmitting side and a data receiving side in the system. FIG. 9 is a diagram showing a data flow between a data transmitting side and a data receiving side of the SR (Selective Repeat) method. FIG. 10 shows a conventional variable-length packet SR (Selec
FIG. 2 is a diagram showing a data flow between a data transmitting side and a data receiving side of a tive repeat) system. FIG. 11 is a diagram showing a flow of data between a data transmission side and a data reception side of the conventional variable length packet GBN (Go Back N) system.

A case will be described in which a conventional ARQ error correction method uses a variable length packet instead of a fixed length packet. Generally, the meaning of using variable length packets is
When the error occurrence rate is low in a communication network, the throughput is gained by increasing the packet size, and when the error occurrence rate is high, the number of retransmission failures is reduced by reducing the packet size. Therefore, when a “retransmission request” is received, it is desirable to determine that the error occurrence rate is high and reduce the packet size.

A case where variable length packet communication is used in the GBN system as shown in FIG. 11 will be described.
If an error occurs in a packet with N (S) = 5, the data receiving side detects a sequence number mismatch at the time of receiving the next packet with a transmission sequence number N (S) = 6, and sends a “reject request” (Reject request). )
Is transmitted to the data transmitting side. Packets with transmission sequence numbers N (S) = 6 to N (S) = 9 received by the data receiving side until the data transmitting side receives the “retransmission request” (Reject) are discarded.

[0006] When the data transmitting side receives the "retransmission request" (Reject), it retransmits the packet with the transmission sequence number N (S) = 5. The packet with the transmission sequence number N (S) = 5 retransmitted at this time is the original transmission sequence number transmitted when the error occurred.
Packets of N (S) = 5 are divided (here, divided into three), and a part of the packets is retransmitted to reduce the packet size.

[0007] The remaining two packets are divided into a packet with a transmission sequence number N (S) = 6 and a transmission sequence number N
(S) = 7 is retransmitted. FIG. 7 shows a state of the division at this time.

[0008] Then, the data transmitting side again divides the packet having the original transmission sequence number N (S) = 5, retransmits the packets with the transmission sequence numbers N (S) = 5 to N (S) = 7, and then again Is transmitted as a packet with the transmission sequence number N (S) = 8.

Similarly, the original transmission sequence number N (S) = 7, N (S) =
8, N (S) = 9 packets are sent with transmission sequence numbers N (S) = 9, N (S) =
10, and transmitted as N (S) = 11. In the GBN (Go BackN) system, such a variable length packet communication has been performed.

As described above, in the GBN system, a new packet can be transmitted without waiting for a delivery confirmation from the data receiving side. When a retransmission request for an erroneous packet arrives, all packets transmitted after the packet are retransmitted, so that control is simple, but transmission efficiency is reduced.

For example, in the example shown in FIG.
When an error occurs in the packet of (S) = 5, the data receiving side detects a sequence number mismatch at the time of receiving the next packet of transmission sequence number N (S) = 6, and “retransmission request” (Reject) Is transmitted to the data transmitting side.

When the data transmitting side receives the "retransmission request" (Reject), it retransmits the packet with the transmission sequence number N (S) = 5, and this is received by the data receiving side. During this time, packets with transmission sequence numbers N (S) = 6 to N (S) = 9 received by the data receiving side are discarded. Then, after retransmitting the packet with the transmission sequence number N (S) = 5, the data transmission side restarts transmission from the transmission sequence number N (S) = 6. Therefore, the retransmission delay time is long, and it takes time to return to the normal communication state.

As another method, an SR (Selecti) shown in FIG.
ve Repeat) method. This SR method can also deliver a new packet without waiting for delivery confirmation from the receiving station.

The SR system differs from the GBN system in that only error frames are retransmitted. Although this is the most efficient method, the control becomes slightly complicated. Transmission order number as shown in FIG.
If an error occurs in a packet with N (S) = 5, the data receiving side detects a sequence number mismatch at the time of receiving the next packet with transmission sequence number N (S) = 6, and sends a “retransmission request” (Selecti
ve Reject) to the data sender.

On the data receiving side, a "retransmission request" (Selective R
eject), the packet with the transmission sequence number N (S) = 5 is retransmitted and received by the data receiving side. During this time, packets with transmission sequence numbers N (S) = 6 to N (S) = 9 received by the data receiving side are temporarily stored. Then, the data transmitting side retransmits only the packet with the transmission sequence number N (S) = 5. Thereafter, the data transmission side restarts transmission from the packet with the transmission sequence number N (S) = 10. Therefore, the retransmission delay is short, and the return to the normal communication state is faster than in the GBN method.

For example, in the example shown in FIG.
If an error occurs in a packet with N (S) = 5, the data receiving side detects a sequence number mismatch at the time of receiving the next packet with transmission sequence number N (S) = 6, and sends a “retransmission request” (Selecti
veReject) to the data transmission side.

[0017] The data transmission side receives a retransmission request (Selective Rejec).
The packets of the transmission sequence numbers N (S) = 6 to N (S) = 9 received on the data receiving side until the reception of t) are temporarily stored. When receiving the retransmission request (Selective Reject), the data transmitting side retransmits the packet of N (S) = 5. At this time, the packet of the transmission sequence number N (S) = 5 retransmitted is obtained by dividing the packet of the original transmission sequence number N (S) = 5 transmitted at the time of occurrence of an error as shown in FIG. ), And the remaining two packets are sent by the transmission sequence number.
The packet is retransmitted as a packet with N (S) = 6 and a packet with transmission sequence number N (S) = 7.

[0018]

However, the conventional S
In the R system, the transmission sequence numbers N (S) = 6 and N (S) = 7 previously transmitted and temporarily stored and the divided and retransmitted transmission sequence numbers N (S) = 6, N (S) The transmission order numbers of the packets of = 7 match, and the following problem occurs.

That is, as shown in FIG. 10, since the packets of N (S) = 6 and N (S) = 7 which have been transmitted normally have already been received by the data receiving side, The retransmitted packets of N (S) = 6 and N (S) = 7 are discarded as sequence number mismatch. Then, there is a possibility that a retransmission request (Selective Reject) with the transmission sequence number N (S) = 10 is transmitted to the data transmitting side. At the same time, the data receiving side concatenates the packet with the transmission sequence number N (S) = 6 that was previously transmitted and temporarily stored after the divided and retransmitted packet with the transmission sequence number N (S) = 5, Data loss may occur.

The present invention solves the above-mentioned problem. By providing a retransmission identification flag in a packet and setting a sub-transmission sequence number in the retransmission packet, an ARQ (Automatic Repeat Request) error correction of the SR (Selective Repeat) method is performed. It is an object of the present invention to provide a variable-length packet communication method and a packet communication device which can be re-transmitted after being divided into small packets even when performing the packet communication.

[0021]

In order to achieve the above object, according to the present invention, a retransmission identification flag is provided for a packet, and a retransmission packet is divided into smaller packets with the same sequence number and retransmitted. Is provided with a sub-transmission sequence number, and a retransmission packet end flag is provided to identify the last retransmission packet having the same sequence number.

According to the present invention, the SR (Selective Rep.
Even when ARQ (Automatic Repeat Request) error correction of the (eat) method is performed, variable-length packet communication can be performed.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an ARQ (Automatic R) of an SR (Selective Repeat) system.
epeatRequest) When performing error correction, the communication packet at the time of normal communication (at the time of non-retransmission), the opening flag,
Ending flag, transmission sequence number, retransmission identification flag,
The communication packet at the time of retransmission includes an opening flag, an ending flag, a transmission sequence number, a retransmission identification flag, a subtransmission sequence number, a retransmission end flag, data, and a CRC error detection code. Activating the retransmission identification flag at the time of retransmission indicates that the packet is a divided retransmission packet.By providing a subtransmission sequence number for each divided data, retransmission with a smaller packet size is enabled. This is a variable length packet communication method that indicates the end of retransmission. When the error rate is low in the communication network, the packet size is increased to increase the throughput, and when the error rate is high, the packet size is reduced to reduce the packet size. If you can reduce the number of failures Cormorant having an effect.

According to a second aspect of the present invention, in the transmission section, a transmission data amount measuring means for measuring a data amount of the transmission data and outputting the transmission data amount, and an error for calculating an error detection code of the transmission data. A detection code calculation unit; packet size determination means for determining a packet size based on the amount of transmission data and the presence / absence of a received retransmission request message; and increasing the number by one each time one packet of transmission data is input and transmitting. A transmission sequence number counter that outputs a sequence number, and a transmission sub-number that increments the number by one each time one packet of transmission data is input, counts up the transmission sub-sequence number by one, and outputs a transmission sub sequence number counter value Sequence number counter, sequence number storage memory for retransmission, and data to be transmitted are stored. Applicable when the sequence number requested for retransmission is input. A data storage memory for retransmission that outputs data of the sequence number as retransmission data, and multiplexes and transmits transmission data, an error detection code, a transmission sequence number, and a transmission sub sequence number based on the packet size output from the packet size determination unit. A multiplexing means for outputting as multiplexed data, a changeover switch for switching data to be given to the multiplexing means as a transmission sequence number, and an RF module, wherein the receiving unit converts the received multiplexed data into an error detection code, received data, A receiving sequence number, a separating unit for separating into a receiving sub-sequence number, an error detecting code calculating unit for calculating an error detecting code based on the received data and outputting an error detecting code calculating result, and a received error detecting code. An error detection code comparator that compares the error detection code operation results and outputs an error detection code comparison result; And a reception sequence number comparator for comparing the reception sequence number of the counter output value with the reception sequence number received, and comparing the received reception sub sequence number and the reception sub sequence number of the counter output value to output a reception sequence number comparison result, A reception sequence number counter that increments the reception sequence number by one each time one packet of data is received while the reception sequence number comparator does not output a retransmission request, and outputs a reception sequence number. A reception sub-sequence number counter that increments the reception sub-sequence number by one each time one packet is received and outputs the reception sub-sequence number, and turns off when the error detection code comparator indicates that there is an error. When the error detection code comparison result indicates no error, the signal is turned on and the switch for transmitting the received data to the next stage is compared with the reception sequence number comparator. A switch that turns off when the result does not match, and turns on when the result of comparison of the reception sequence numbers matches, and that transmits the input reception data to the next stage. When the retransmission identification flag of the received packet indicates "retransmission", the comparison is performed for both the reception sequence number and the reception sub-sequence number, and when the retransmission identification flag indicates "non-retransmission", only the reception sequence number is compared. The packet communication device is characterized by performing the following: when the error rate is low in the communication network, the packet size is increased to increase the packet size, and when the error rate is high, the packet size is decreased to reduce the number of retransmission failures. It has the effect of being able to reduce. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are block diagrams of a transmitting section and a receiving section of a packet communication apparatus according to an embodiment of the present invention. FIG. 3 is a diagram showing a packet configuration at the time of normal transmission and a packet configuration at the time of retransmission in the variable length packet communication method according to the embodiment of the present invention. FIG. 4 shows a format of the N (S) field in the embodiment of the present invention. FIG. 5 shows a format of the sub M (S) field in the embodiment of the present invention. FIG. 6 shows an SR (Selective) of the variable length packet communication method according to the embodiment of the present invention.
FIG. 3 is a diagram showing a data flow between a data transmitting side and a data receiving side of a (Repeat) method.

In the transmission section shown in FIG. 1, reference numeral 23 denotes a changeover switch for switching transmission data. Changeover switch 2
3 outputs the retransmission request message (for transmission) at the first priority, the retransmission data at the second priority, and the quantization index of the new transmission data at the third priority for the three inputs. Switch to

Reference numeral 28 denotes transmission data amount measuring means for measuring the data amount of transmission data (data selected by the changeover switch 23) and outputting the transmission data amount. An error detection code operation unit 29 calculates an error detection code of transmission data (data selected by the changeover switch 23).

Reference numeral 31 denotes a packet size determining means for determining a packet size based on the amount of transmission data and the presence or absence of a received retransmission request message.

Reference numeral 26 denotes a transmission sequence number counter which increments the number by one each time transmission data is input by a given packet size value and outputs a transmission sequence number. 25 denotes an input signal line of the transmission sequence number counter 26. This is the switch inserted in. When sending retransmission data, the switch 25 is turned off, and the transmission data (retransmission data) is
, The transmission sequence number counter 26 does not operate.

A transmission sub-sequence number counter 46 counts up the transmission sub-sequence number by one each time the transmission data selected by the given packet size value is input and outputs it as a transmission sub-sequence number counter output value. It is. Reference numeral 45 denotes a switch inserted in the input signal line of the transmission sub-sequence number counter 46.

Reference numeral 39 denotes a retransmission sequence number storage memory.
Reference numeral 40 denotes a retransmission data storage memory for storing a quantization index of data to be transmitted, and outputting, as retransmission data, data having a corresponding sequence number when a sequence number requested for retransmission is input.

Reference numeral 30 denotes a transmission multiplex which multiplexes transmission data (data selected by the changeover switch 23), an error detection code, a transmission sequence number, and a transmission sub sequence number based on the packet size output from the packet size determination means 31. Multiplexing means for outputting as multiplexed data.

Reference numeral 27 denotes a multiplexing means 30 as a transmission sequence number.
This is a changeover switch for changing data to be supplied to the switch. 47
Is a switch for switching whether or not to transmit the output data from the transmission sub-sequence number counter 46. Reference numeral 24 denotes a switch changeover determining means, which sends a switch changeover signal to the switches 23, 25, 27 and 45.

Reference numeral 32 denotes baseband processing means for converting transmission multiplexed data into baseband data, and reference numeral 33 denotes an RF module.

In the receiving section shown in FIG. 2, reference numeral 34 denotes a demultiplexing means for separating the received multiplexed data into an error detection code, received data, a reception sequence number, and a reception sub-sequence number. 3
Reference numeral 5 denotes an error detection code calculation unit that calculates an error detection code based on the received data and outputs an error detection code calculation result.
36 is a switch.

An error detection code comparator 37 compares the received error detection code with the error detection code operation result and outputs the error detection code comparison result.

Reference numeral 38 denotes a reception sequence number counter for increasing the reception sequence number by one each time one packet of data is received and outputting the reception sequence number. Reference numeral 48 denotes a reception sub-sequence number counter which increases the reception sub-sequence number by one each time one packet of data is received and outputs the reception sub-sequence number only in the case of "retransmission". When the RIF (retransmission identification flag) shown in FIG. 4 indicates “non-retransmission”, the reception sub sequence number counter 48 does not increment the reception sub sequence number. Also, the receiving sequence number comparator 4
While the "retransmission request" from 1 is being input, neither the reception sequence number counter 38 nor the reception sub sequence number counter 48 counts up.

Reference numeral 41 compares the received reception sequence number (output from the demultiplexing unit 34) with the reception sequence number of the counter output value, and compares the received reception sub-sequence number (output from the demultiplexing unit 34) with the counter output value. This is a reception sequence number comparator that compares reception sub sequence numbers and outputs a reception sequence number comparison result. The reception sequence number comparator 41 is provided with the RIF shown in FIG.
When the (retransmission identification flag) indicates "retransmission", comparison is performed for both the reception sequence number and the reception sub-sequence number. When the RIF (retransmission identification flag) indicates "non-retransmission", the reception sequence number is used. Only the comparison is made. 44
Is data type identification means.

Reference numeral 36 denotes OFF when the error detection code comparison result does not match (there is an error), and turns ON when the error detection code comparison result matches (there is no error). This is a switch to send to the stage. Reference numeral 42 denotes a switch that is turned off when the reception order number comparison results do not match, and is turned on when the reception order number comparison results match, and that sends input reception data to the next stage.

First, an ARQ (Automatic Repeat Request) error correction method according to an embodiment of the present invention will be described with reference to FIGS.

As an explanation of terms, the primary station is a station to which data is to be transmitted, and the secondary station is a station that receives data from the primary station and returns a response.

Referring to FIGS. 1 and 2, the operation when no error occurs on the communication network will be described. At this time, in the primary station, no retransmission data or a retransmission request message (for transmission) has been input to the switch 23, and the switch switching determination means 24 outputs a switch switching signal for switching the switch 23 to output new transmission data. Is output. The switch 23 switches based on a switch switching signal.

The switch switching determining means 24 includes a switch switching signal for switching the switch 25 to be turned on, a switch switching signal for switching the switch 27 so as to output the transmission sequence number counter output value, and a switch 45 for the switch 45. A switch switching signal that switches to be turned off is output.

The new transmission data passes through the switch 23,
Switch 25, switch 4 as selected transmission data
5. Retransmission data storage memory 40, transmission data amount measurement unit 28, error detection code operation unit 29, and multiplexing unit 30
Is input to The switch 25 switches based on a switch switching signal.

The selected transmission data passes through the switch 25 and is input to the transmission sequence number counter 26. The transmission sequence number counter 26 counts up the transmission sequence number by one each time the transmission data selected by the given packet size value is input and outputs it as a transmission sequence number counter output value. The selected transmission data is switched 4
5 cannot be transmitted to the transmission sub-sequence number counter 46. The changeover switch 27 is switched based on the above-described switch changeover signal, and outputs the output value of the transmission sequence number counter 26 as the transmission sequence number.

The retransmission data storage memory 40 holds the selected transmission data. The transmission data amount measuring means 28
It measures the amount of input transmission data and outputs the amount of transmission data. The packet size determining means 31 determines the packet size based on the amount of transmission data and the presence / absence of the received “retransmission request”, and outputs the packet size. The error detection code operation unit 29 calculates an error detection code of the selected transmission data and outputs an error detection code.

The switch 47 is turned off here based on the above-mentioned switch switching signal, and the transmission sub-sequence number is not output. The multiplexing means 30 multiplexes the selected transmission data, transmission sequence number, and error detection code based on the input packet size, and outputs the multiplexed data as transmission multiplexed data. The transmission multiplexed data is converted into baseband data by the baseband processing means 32 and is converted into radio waves by the RF module 33.

The radio wave received by the secondary station is converted to baseband data by the RF module 33 and converted to received data by the baseband processing means 32. Next, description will be made with reference to FIG.

The received multiplexed data is input to the demultiplexing means 34 and demultiplexed into received data, a received error detection code, and a reception sequence number. The received data is input to the switch 36 and the error detection code operation unit 35. The error detection code calculation unit 35 calculates an error detection code of the received code and outputs an error detection code calculation result. The error detection code comparator 37 compares the received error detection code with the error detection code calculation result, and if they match, the error detection code comparator 37 outputs "no error" as an error presence / absence signal. At this time, the switch 36 is turned on, and the switch 36 outputs received data.

The received data that has passed through the switch 36 is input to the data type identification means 44 and the switch 43. The data type identification means 44 identifies whether the input received data is a command such as "retransmission request" or normal communication data, and switches the switch 43 based on this.

If the input received data is a command such as "retransmission request", the switch 43 is switched upward, and if it is normal communication data, the switch 43 is switched downward. Here, the received data is not a command but communication data such as an image, so the data type identification means 44 outputs non-command data, the switch 43 switches to the lower side, and the received data passes through the switch 43 and is sent to the switch 42. Can be

The reception sequence number / comparator 41 operates only when the "error-free" signal is output from the error detection code comparator 37 as an error presence / absence signal and the non-command data is output from the data type identification means 44. . Here, when the RIF (retransmission identification flag) shown in FIG. 4 indicates “retransmission”, the reception sequence number / comparator 41 compares both the reception sequence number and the reception sub sequence number. The reception order number / comparator 41 compares only the reception order number when the RIF (retransmission identification flag) indicates “non-retransmission”.

Here, since the data is not retransmission but new data, only the reception sequence number is compared, and the demultiplexing means 34
Sequence number and reception sequence number counter 3 output from
8, the output values of the reception sequence number counters match, and it is determined that data has been normally received, and the reception sequence number / comparator 41 outputs information indicating that retransmission is unnecessary.

In accordance with the information indicating that retransmission is unnecessary from the reception sequence number / comparator 41, the switch 42 is turned on, and the received data is output from the switch 42 and transmitted to the next stage.
At the same time, information indicating that retransmission is unnecessary is performed by the reception sequence number counter 38.
And to the reception sub-sequence number counter 48. FIG.
(Retransmission identification flag) indicates "non-retransmission", the reception sequence number counter 38 counts up the reception sequence number by 1, but the reception sub sequence number counter 48 does not count up the reception sub sequence number. .

Next, referring to FIGS. 1 and 2, the operation when an error occurs on the communication network will be described. In the reception operation of the secondary station, the error detection code comparator 37 compares the received error detection code with the error detection code calculation result, and when they do not match, the error detection code comparator 37 outputs "error present" as an error presence / absence signal. Is output. When the signal of “error exists” is input as the error presence / absence signal, the switch 36 is turned off, and the received data at this time is discarded. The receiving sequence number comparator 41 does not operate when the signal of “error” is input. Thus, the error detection code comparator 3
7 merely outputs a signal indicating that there is an error, the received data is only discarded, and no retransmission request is made. When the output signal of the error detection code comparator 37 transitions from "error present" to "no error", a retransmission request is issued as follows.

When the error detection code received by the error detection code comparator 37 matches the error detection code calculation result and outputs “no error”, the switch 36 is turned on, and the switch 36 outputs received data. You. The received data is input to the data type identification means 44 and the switch 43. At this time, the input data is communication data other than the command. Therefore, the data type identification means 44 outputs non-command data, the switch 43 is switched to the lower side, and the received data passes through the switch 43 and is transmitted to the switch 42. Is entered.

The error detection code comparator 37 outputs "no error" and is not a retransmission. Therefore, the reception sequence number comparator 41 compares only the reception sequence number. Therefore, the reception sequence number comparator 41 compares the reception sequence number output from the demultiplexing means 34 with the reception sequence number counter output value output from the reception sequence number counter 38.

At this time, the previous data has been discarded due to an error, and at this time the count has not been counted up, so that the comparison results do not match. As described above, when the comparison results do not match, the reception sequence number comparator 41 outputs a “retransmission request”.

The operation of the switch 42 to which the “retransmission request” has been input and the handling of the received data at this time are determined by GBN (Go Back
It depends on whether it is N) or SR (Selective Repeat). In the case of the GBN system, the switch 42 is turned off, and the received data at this time is discarded.
2 is turned on, and the received data at this time is stored and used after being linked with the previous data retransmitted.

The “retransmission request” is the reception sequence number counter 38
Is also input to the reception sub sequence number counter 48. While the “retransmission request” is being input, the reception sequence number counter 3
8. The count of any of the reception sub sequence number counters 48 does not count up.

The "retransmission request" is also input to the switch 23 and the switch changeover determining means 24. At this time, the switch changeover determining means 24 is a switch changeover signal that switches to output a “retransmission request” transmitted by the switch 23, a switch changeover signal that switches so that the switch 25 is turned off, and a reception sequence number A switch switching signal that switches so as to output a counter output value and a switch switching signal that switches so that the switch 45 is turned off are output.

The switch 23 is switched to output a "retransmission request" by a switch switching signal. The "retransmission request" to be transmitted passes through the switch 23, and as the selected transmission data, the switch 25, the switch 45, the retransmission data storage memory 40, the transmission data amount measurement unit 28, the error detection code calculation unit 29, and the multiplexing unit. 30 is input.

The switch 25 is turned off by a switch switching signal. The changeover switch 27 switches based on the switch changeover signal, and outputs the output value of the reception sequence number counter as the transmission sequence number. The switch 45 is turned off here by a switch switching signal.

The transmission data amount measuring means 28 measures the data amount of the input transmission data and outputs the transmission data amount. The packet size determining means 31 determines the packet size based on the amount of transmission data and the presence / absence of the received “retransmission request”, and outputs the packet size. The error detection code operation unit 29 calculates an error detection code of the selected transmission data and outputs an error detection code.

The multiplexing means 30 multiplexes the selected transmission data, transmission sequence number, and error detection code based on the input packet size, and outputs the multiplexed data as transmission multiplexed data. The transmission multiplexed data is converted into baseband data by the baseband processing means 32 and is converted into radio waves by the RF module 33. In this way, the “retransmission request” is transmitted from the secondary station to the primary station.

The primary station having received the "retransmission request" operates as follows. The radio wave received by the primary station is converted into baseband data by the RF module 33 and is converted into received data by the baseband processing means 32. The received multiplexed data is input to the demultiplexing means 34 and demultiplexed into received data, a received error detection code, and a reception sequence number. The received data is input to the switch 36 and the error detection code operation unit 35.

The error detection code calculation unit 35 calculates an error detection code of the received code and outputs an error detection code calculation result.
The error detection code comparator 37 compares the received error detection code with the error detection code calculation result, and if they match, the error detection code comparator 37 outputs "no error" as an error presence / absence signal. At this time, the switch 36 is turned on, and the switch 3
6 outputs received data. The received data is input to the data type identification means 44 and the switch 43.

The data type identifying means 44 identifies whether the input received data is a command such as "retransmission request" or normal communication data, and switches the switch 43 based on this. Here, since the input received data is the command “retransmission request”, the switch 43 is switched upward.

The received “retransmission request” is input to the retransmission data storage memory 40, the retransmission sequence number storage memory 39, and the packet size determination means 31. The error detection code comparator 37 outputs a "no error" signal as an error presence / absence signal. However, the reception order number / comparator 41 does not operate because the data type identification means 44 identifies the command data. Therefore, the switch 42 is off.

When the received “retransmission request” is input to the retransmission sequence number storage memory 39, the retransmission data corresponding to the input reception sequence number at this time is output from the retransmission data storage memory 40. As described above, the retransmission sequence number storage memory 39 and the retransmission data storage memory 40 have a one-to-one correspondence.
Is linked to.

The retransmission data is determined by the switch switching determining means 2
4 is input. When retransmission data is input to the switch switching determining means 24, the switch switching determining means 24
Is a switch switching signal for switching the switch 23 to output retransmission data, a switch switching signal for switching the switch 25 to be off, and a switch for switching the switching switch 27 to output the output value of the reception sequence number counter. Switching signal and switch 4
5 is output as a switch changeover signal that is switched to turn on.

The switch 23 is switched to output retransmission data by a switch switching signal. The retransmission data passes through the switch 23, and switches 25, 45, a retransmission data storage memory 40, transmission data It is input to the quantity measuring means 28, the error detection code calculating section 29, and the multiplexing means 30.

The switch 25 is off, the selected transmission data (retransmission data) cannot pass through the switch 25,
The transmission sequence number counter 26 does not operate. The changeover switch 27 outputs a reception sequence number counter output value as a transmission sequence number in accordance with the switch change signal. The switch 45 is turned on by a switch switching signal,
The selected transmission data is output from the switch 45 and sent to the transmission sub-sequence number counter 46.

When transmitting retransmission data, retransmission data storage memory 40 does not perform a rewrite operation. The transmission data amount measuring unit 28 measures the data amount of the input transmission data and outputs the transmission data amount. The packet size determining means 31 determines and outputs the packet size based on the amount of transmission data and the presence or absence of the received retransmission request.

Since the received "retransmission request" has been input, the packet size determining means 31 generally selects a packet size smaller than the previously transmitted packet size. That is, retransmission data is divided to form a retransmission packet, and retransmission is performed. Transmission sub sequence number counter 46
Outputs a transmission sub-sequence number counter output value by incrementing the transmission sub-sequence number by one each time transmission data selected by a given packet size value is input.

The switch 47 is switched on the basis of a switch switching signal. Since the output value of the reception sequence number counter is output from the changeover switch 27, the switch 47 is turned on and the transmission sub sequence number is output.

The error detection code calculation section 29 calculates an error detection code of the selected transmission data and outputs an error detection code. The multiplexing means 30 multiplexes the selected transmission data, transmission sequence number, transmission sub-sequence number and error detection code based on the input packet size, and outputs the multiplexed data as transmission multiplexed data. At this time, the multiplexing means 30
Set the RIF (retransmission identification flag) shown in
If there is retransmission data following the data to be retransmitted at present, REF (retransmission end flag) shown in FIG. 5 is set to “retransmission not completed”. The transmission multiplexed data is converted into baseband data by the baseband processing means 32,
It is converted into radio waves by the module 33.

In this way, the response data to the "retransmission request" is transmitted from the primary station to the secondary station. The transmitting side of the primary station operates similarly until the transmission of a series of retransmission data is completed. By setting the REF (retransmission end flag) shown in FIG. 5 to “retransmission end” when transmitting the last data of the continuous retransmission data, the last packet of a series of divided retransmission data can be transmitted. To the secondary station.

The radio wave received by the secondary station is converted into baseband data by the RF module 33 and converted into received data by the baseband processing means 32. The received multiplexed data is input to the demultiplexing means 34 and demultiplexed into received data, a received error detection code, and a reception sequence number. The received data is input to the switch 36 and the error detection code operation unit 35. The error detection code calculation unit 35 calculates an error detection code of the received code and outputs an error detection code calculation result. The error detection code comparator 37 compares the received error detection code with the error detection code calculation result, and if they match, the error detection code comparator 37 outputs "no error" as an error presence / absence signal. At this time, the switch 36 is turned on, and the switch 36 is turned on.
Output the received data.

The received data is input to the data type identification means 44 and the switch 43. The data type identification means 44 identifies whether the input received data is a command such as "retransmission request" or normal communication data, and switches the switch 43 based on this. Here, since the input received data is not a command, the switch 43 is switched to the lower side, and the received data passes through the switch 43 and is
2 is input.

As described above, only when the error detection code comparator 37 outputs the "no error" signal as the error presence / absence signal and the data type identification means 44 outputs the non-command data, the reception sequence number / comparison The vessel 41 operates. The operation of the reception sequence number / comparator 41 is the same as that shown in FIG.
When the IF (retransmission identification flag) indicates “retransmission”, the reception order number and the reception sub-sequence number are compared, and when the RIF (retransmission identification flag) indicates “non-retransmission”, the reception order is determined. Only the numbers are compared. Here, since the communication data is retransmitted, both the reception sequence number and the reception sub sequence number are compared, and the reception sequence number output from the demultiplexing unit 34 and the reception sequence number output from the reception sequence number counter 38 are output. If the values match and the reception sub-sequence number output from the demultiplexing means 34 matches the reception sub-sequence number counter 48, it is determined that data has been normally received, and the reception sequence number / comparator 4
1 outputs information indicating "retransmission is unnecessary". When the reception sequence number / comparator 41 outputs information indicating “retransmission unnecessary”,
The switch 42 is turned on, and the switch 42 outputs received data.

At the same time, information indicating “retransmission unnecessary” is input to the reception sequence number counter 38 and the reception sub sequence number counter 48. At this time, since the RIF (retransmission identification flag) shown in FIG. 4 indicates "retransmission", the reception sub sequence number counter 48 counts up the reception sub sequence number by one. Further, since the REF (retransmission end flag) shown in FIG. 5 indicates "retransmission not completed", the reception sequence number counter 38 does not count up the reception sequence number.

In this way, retransmission data from the primary station to the secondary station is received. The receiving side of the secondary station operates in the same manner until the reception of a series of retransmission data is completed. And FIG.
When a packet whose REF (retransmission end flag) is set to “retransmission end” is received, it is recognized that the last packet of a series of divided retransmission data has been received.
At this time, the RIF (retransmission identification flag) shown in FIG.
Increments the reception sub-sequence number by one. Also,
Since the REF (retransmission end flag) shown in FIG. 5 indicates "end of retransmission", the reception sequence number counter 38 increments the reception sequence number by one. Thereafter, if no error occurs on the communication network, the state transitions to a normal communication state.

FIG. 6 shows a case where variable length packet communication is performed using the SR method in such an ARQ error correction method.
This will be described with reference to FIG. When an error occurs in the packet with the transmission sequence number N (S) = 5, the data receiving side detects the sequence number mismatch when the next packet with the transmission sequence number N (S) = 6 is received, and requests the retransmission. Selective Reject) to the data sender. The data sending side sends a retransmission request (Selective
The packets of the transmission sequence numbers N (S) = 6 to N (S) = 9 received on the data receiving side until the reception of “Reject” are temporarily stored.

The data transmitting side sends a retransmission request (SelectiveRejec
At the time point t), the packet with the original transmission sequence number N (S) = 5 is divided (here, divided into three), and the transmission sub-sequence numbers M (S) = 0 and M (S) = 1. Add M (S) = 2 and retransmit. FIG. 3 shows a state of the division at this time.

The RIF (retransmission identification flag) of the N (S) field of a packet to be retransmitted after being divided and added with the transmission subsequence number is transmitted with "retransmission" set in a format as shown in FIG. . And M (S) = 0 and M (S) = 1
The REF (retransmission end flag) of the sub-M (S) field of the packet No. is set to “retransmission not completed” in the format shown in FIG. 5, and the sub-M (S) of the packet of M (S) = 2 is set. In the REF (retransmission end flag) of the field, “retransmission end” is set.

The data receiving side checks the RIF of the N (S) field.
It recognizes that retransmission has been started from the time when a packet whose (retransmission identification flag) indicates “retransmission” can be received, and when the REF (retransmission end flag) of the sub M (S) field can receive “retransmission end”. It recognizes that retransmission has ended. The sub-sequence numbers M (S) = 0, M (S) = 1, and M (S) = 2 received during this time are concatenated to form a packet of N (S) = 5. Then, the packet with the sequence number N (S) = 5 is linked to the sequence number N (S) = 4, and the temporarily stored N (S) = 6 to N
The packet of (S) = 9 is concatenated after the packet of N (S) = 5.

As described above, according to the variable length packet communication method of the present invention, the ARQ (Aut
omatic Repeat Request)
Variable length packet communication can be performed.

[0089]

As is apparent from the above description, according to the present invention, an ARQ (Automated Automated Mode) of the SR (Selective Repeat) method is used.
(atic Repeat Request) Even if error correction is performed, variable-length packet communication is enabled.Thus, when the error rate is low in the communication network, the packet size is increased to increase the throughput, and when the error rate is high, the packet is increased. By reducing the size, the number of retransmission failures can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission unit of a packet communication device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a receiving unit of the packet communication device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a packet configuration at the time of normal transmission and a packet configuration at the time of retransmission in the variable length packet communication method according to the embodiment of the present invention.

FIG. 4 is a format diagram of an N (S) field in the variable length packet communication method according to the embodiment of the present invention.

FIG. 5 is a format diagram of a sub M (S) field of the variable length packet communication method according to the embodiment of the present invention.

FIG. 6 is a diagram showing a data flow between a data transmission side and a data reception side of an SR (Selective Repeat) method of a variable length packet communication method according to an embodiment of the present invention.

FIG. 7 is a diagram showing a conventional packet configuration during normal transmission and a packet configuration during retransmission.

FIG. 8 is a diagram showing a data flow between a data transmission side and a data reception side in a conventional GBN (Go Back N) system.

FIG. 9 is a diagram showing a flow of data between a data transmission side and a data reception side of an SR (Selective Repeat) method.

FIG. 10 shows a conventional variable length packet SR (Selective Rep).
diagram showing the flow of data between the data sender and the data receiver using the (eat) method

FIG. 11 shows a conventional variable-length packet GBN (Go Back N).
Diagram showing the data flow between the data sending side and the data receiving side of the system

[Explanation of symbols]

 REFERENCE SIGNS LIST 23 changeover switch 24 switch changeover determination means 25 switch 26 transmission sequence number counter 27 changeover switch 28 transmission data amount measurement means 29 error detection code operation unit 30 multiplexing means 31 packet size determination means 32 baseband processing means 33 RF module 34 separation Means 35 Error detection code operation unit 36 Switch 37 Error detection code comparator 38 Reception sequence number counter 39 Retransmission sequence number storage memory 40 Retransmission data storage memory 41 Reception sequence number / comparator 42 Switch 43 Switch 44 Data type identification means 45 Switch 46 Transmit sub sequence number counter 47 Switch 48 Receive sub sequence number counter

Claims (2)

[Claims] When performing ARQ error correction of the SR method, a communication packet at the time of normal communication, that is, at the time of non-retransmission, includes an opening flag, an ending flag, a transmission sequence number, a retransmission identification flag, data, and a CRC error detection code. The communication packet at the time of retransmission includes an opening flag, an ending flag, a transmission sequence number, a retransmission identification flag, a subtransmission sequence number, a retransmission end flag, data, and a CR.
A retransmission identification flag is activated at the time of retransmission to indicate that the packet is a divided retransmission packet, and a subtransmission sequence number is provided for each divided data to perform retransmission with a smaller packet size. A variable length packet communication method, wherein the retransmission end flag indicates the end of divisional retransmission. 2. A transmission unit, comprising: a transmission data amount measuring means for measuring a data amount of transmission data and outputting the transmission data amount; an error detection code operation unit for calculating an error detection code of the transmission data; A packet size determining means for determining a packet size based on the presence or absence of a received retransmission request message; a transmission sequence number counter for increasing a number by one each time one packet of transmission data is input and outputting a transmission sequence number; Each time one packet of transmission data is input, increments the number by one, increments the transmission sub-sequence number by one, and outputs a transmission sub-sequence number counter value, and stores a retransmission sequence number. Stores the data to be transmitted and the data to be transmitted, and when the sequence number requested for retransmission is entered, retransmits the data with the corresponding sequence number. A transmission data, an error detection code, a transmission sequence number, and a transmission sub-sequence number are multiplexed based on the packet size output from the packet size determination means and output as transmission multiplexed data. A multiplexing means, a changeover switch for switching data to be given to the multiplexing means as a transmission sequence number, and an RF module, wherein the reception section converts the reception multiplexed data into an error detection code, reception data, reception sequence number, reception sub A demultiplexing unit that separates the received error detection code into a sequence number, an error detection code operation unit that calculates an error detection code based on the received data and outputs an error detection code operation result, An error detection code comparator for comparing and outputting an error detection code comparison result, and a reception order number and a reception order of a counter output value A reception sequence number comparator for comparing the received sub sequence number with the reception sub sequence number of the counter output value and outputting a reception sequence number comparison result; and A reception sequence number counter that increments the reception sequence number by one each time one packet of data is received while the data is not output and outputs a reception sequence number, and a reception sub-number each time one packet of data is received only for retransmission data A reception sub-sequence number counter that outputs a reception sub-sequence number by incrementing the sequence number by one, and is turned off when the comparison result of the error detection code comparator indicates that there is an error; If no is indicated, the switch is turned on to send the input received data to the next stage, and if the comparison result of the reception sequence number comparator does not match, And a switch for turning on the received data when the result of comparison of the received sequence numbers is coincident and transmitting the input data to the next stage, wherein the received sequence number comparator includes a retransmission identification flag for the transmitted packet. Is characterized by performing a comparison for both the reception sequence number and the reception sub-sequence number when it indicates `` retransmission, '' and comparing only the reception sequence number when the retransmission identification flag indicates `` non-retransmission. '' Packet communication device.