JPH11177536A - Error control system for radio data link layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of throughput and also to suppress the increase of delay by performing the start/stop switching of the error control for a radio data link layer according to the state of a radio channel. SOLUTION: When it is detected that the channel state is deteriorated compared with its reference value, a radio data link layer A sends an ARQ stop request to a radio data link layer B. Receiving the ARQ stop request, the layer B returns an ARQ stop answer to the layer A and stops the ARQ control of the radio data link layers. If a data transmission error occurred thereafter between the higher order layers C and A, the errors including that occurred on a radio circuit are recovered via the control of the higher order layers. The link layer a monitors the state of the radio channel even when the ARQ control is stopped. Then the link layer A sends an ARQ start request to the link layer B when it is detected that the radio channel state is recovered better than its reference value. Thus, the ARQ control is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an error in transmitted data in data communication.

[0002]

2. Description of the Related Art One of the methods for removing an error occurring during communication is an automatic repeater (ARQ).
t Request, automatic retransmission request) control. AR
The Q control is a control method for retransmitting a data unit (frame) containing an error and removing the error. For the ARQ control, see “Automatic Repeat Request”.
est Error-Control Scheme
s "(Shu Lin et al., IEEE Commun. M.
ag. Vol. 22, no. 12, Dec. '84)
In detail.

FIG. 22 shows an example of a protocol stack in data communication. Data generated in the upper layer C of the fixed terminal station is transmitted to the radio base station through the data link layer C and the physical layer C. The data received by the wireless base station is transmitted to the wireless terminal station through the physical layer B, the data link layer B, the wireless data link layer B, and the wireless physical layer B. The data received by the wireless terminal station is transferred to the upper layer A through the wireless physical layer A, the wireless data link layer A, and the data link layer A. Here, in data communication, ARQ control is performed between the upper layer A and the upper layer C in order to transmit data without error (error-free transmission). Further, when a wireless line is interposed on a communication path, ARQ control is generally performed between the wireless data link layer A and the wireless data link layer B as a means for guaranteeing an error in a wireless line having a poor line condition.

A transmission operation of ARQ control between the upper layer A and the upper layer C will be described with reference to FIG. In the upper layer C, if the delivery confirmation and retransmission request for the already transmitted data is not received after the reference time, the transmission data is retransmitted due to timeout. When the timeout does not occur, when a retransmission request for already transmitted data is received, the transmission data is retransmitted. If the retransmission request has not been received, new transmission data is transmitted if there is new data. If there is no new data, the transmission is stopped.

A receiving operation of ARQ control between the upper layer A and the upper layer C will be described with reference to FIG. If there is no received data in the upper layer A, a transmission confirmation for the latest received data is transmitted. When there is the above-mentioned received data, if there is no error in the received data, a delivery confirmation for the latest received data is transmitted. When an error occurs in the received data, a retransmission request for the received data is transmitted.

The transmission operation of ARQ control between the wireless data link layer A and the wireless data link layer B will be described with reference to FIG. In the wireless data link layer B, when a transmission confirmation and retransmission request for already transmitted data is not received for a time exceeding the reference time, the transmission data is retransmitted due to timeout. When the timeout does not occur, when a retransmission request for already transmitted data is received, the transmission data is retransmitted. If the retransmission request has not been received, new transmission data is transmitted if there is new data. If there is no new data, the transmission is stopped.

A receiving operation of the ARQ control between the wireless data link layer A and the wireless data link layer B will be described with reference to FIG. When there is no received data in the wireless data link layer A, a transmission confirmation for the latest received data is transmitted. When there is the above-mentioned received data, if there is no error in the received data, a delivery confirmation for the latest received data is transmitted. When an error occurs in the received data, a retransmission request for the received data is transmitted.

FIG. 27 shows an example of ARQ control according to the above configuration. The figure shows an example in which no error occurs between the upper layer A and the upper layer C and between the wireless data link layer A and the wireless data link layer B. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided data and reproduces the data.

FIG. 28 shows an example in which an error occurs in a relatively good radio channel condition. The crosses in the figure indicate poor reception. N (a3) indicates a retransmission request for the wireless packet a3. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided data and reproduces the data. Up to this point, it is the same as FIG. In FIG. 28, when a reception failure occurs in the wireless packet a3, the wireless data link layer A returns a retransmission request for the existing data to the wireless data link layer B.
The wireless data link layer B retransmits the wireless packet requested by the retransmission request. As described above, when the line condition is relatively good, the retransmission control converges between the wireless data link layer A and the wireless data link layer B with a small transmission delay.
The degradation of throughput is small, and ARQ between wireless data link layers is effective error control.

FIG. 29 shows an example of a case where an error occurs in a state where the radio channel condition is deteriorated. The crosses in the figure indicate poor reception. N (a3) indicates a retransmission request for the wireless packet a3. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided data and reproduces the data. Up to this point, it is the same as FIG. 27 and FIG. Further, T1 is a timeout time in the upper layer ARQ control. Wireless data link layer A
When errors frequently occur between the wireless data link layer B and the wireless data link layer B, the throughput decreases and the transmission delay increases. In the figure, the delivery to the upper layer data A cannot be confirmed, and the timeout period is exceeded. As a result, the upper layer C transmits the retransmission data of the upper layer data a and the upper layer data a ′. The upper layer A receives the data redundantly. As described above, when the line state between the wireless data links deteriorates and retransmission frequently occurs, the ARQ control mismatch between the upper layer and the wireless data link layer deteriorates the throughput.

FIG. 30 shows an example of transmission throughput characteristics in the upper layer when ARQ control is applied to the upper layer and the wireless data link layer. In the figure, the solid line shows the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer (method 1), and the broken line shows that the ARQ control is performed only for the upper layer. AR
This is a throughput characteristic when Q control is not performed (method 2). In the figure, the horizontal axis represents the line state in the wireless line, and the vertical axis represents the throughput characteristic in the upper layer. In the figure, the throughput of the method 2 is deteriorated from the point (1). This is mainly because, as described above, the ARQ control in the wireless data link layer has a smaller round trip delay, and therefore can be efficiently retransmitted. The throughput of the method 1 is deteriorated from the point (2), and the throughput characteristic is reversed at the point (3). This is because retransmission by ARQ control frequently occurs in the wireless data link layer, and as a result, the upper layer AR
The main cause is that a mismatch occurs with the Q control.

[0012]

In the conventional error control system based on ARQ, retransmission is continued until there is no error in the data so that the data can be transmitted without error between the transmitting station and the receiving station. If there is an error control method in the upper layer and an error control method in the wireless data link layer, each error control method tries to guarantee error-free transmission independently, resulting in an increase in unnecessary retransmissions. Decrease and the delay increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and suppresses deterioration of throughput by switching error control in a wireless data link layer between stop and start in accordance with the state of a wireless channel. The purpose is to suppress an increase in delay.

Another object of the present invention is to provide a method capable of realizing the above-mentioned problem without changing an existing upper-layer protocol.

Another object of the present invention is to provide a method for simplifying the control in order to solve the above problems.

[0016]

According to the first aspect of the present invention, there is provided an error control method for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on the wireless data link layer. In the error control method of the wireless data link layer, a line state monitoring means for monitoring a line state, a retransmission control stop means for stopping retransmission control if the line state monitoring result is degraded from a reference value, Retransmission control starting means for starting retransmission control when the value is restored to a value better than the reference value.

An error control method for a wireless data link layer according to a second aspect of the present invention is an error control method for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on the wireless data link layer. In the control method, a line error rate (Bit Error Rate: BE)
R), BER monitoring means for monitoring according to R), retransmission control stopping means for stopping retransmission control if the BER monitoring result BER is degraded from a reference value, and if the BER monitoring result BER recovers to a value better than the reference value. Retransmission control starting means for starting retransmission control.

In the error control method for a wireless data link layer according to the third invention, the retransmission control stopping means includes a BER.
If the BER has deteriorated from the first reference value, the retransmission control is stopped, and the retransmission control start means starts the retransmission control when the BER exceeds the second reference value better than the first reference value.

An error control method for a wireless data link layer according to a fourth aspect of the present invention is an error control method for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on the wireless data link layer. In the control method, the line state is determined by the number of data block errors (Pack
et Error Rate: PER), retransmission control stopping means for stopping retransmission control when the PER monitoring result PER has degraded from a reference value, and a PER monitoring result PER having a value better than the reference value. And retransmission control starting means for starting retransmission control when the status has been restored to

In the error control method for a wireless data link layer according to the fifth invention, the retransmission control stopping means is PER
If the PER has deteriorated from the first reference value, the retransmission control is stopped, and the retransmission control start means starts the retransmission control if the PER exceeds the second reference value better than the first reference value.

According to a sixth aspect of the present invention, there is provided an error control method for a wireless data link layer, wherein an error in the wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on the wireless data link layer. In the control method, a reception signal level monitoring means for monitoring a line state based on a reception signal level, a retransmission control stop means for stopping retransmission control when the reception signal level monitoring result reception signal level becomes lower than a reference value, Retransmission control starting means for starting retransmission control when the level monitoring result received signal level has recovered to a value better than the reference value.

In the error control method for a wireless data link layer according to a seventh aspect, the retransmission control stopping means stops retransmission control when the received signal level is degraded from a first reference value, and the retransmission control starting means receives the signal. When the signal level exceeds a second reference value better than the first reference value, retransmission control is started.

The error control method of the wireless data link layer according to the eighth invention is an error control method of the wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on the wireless data link layer. In the control method, a throughput monitoring means for monitoring a line state based on a transmission throughput of a wireless section, a retransmission control stopping means for stopping retransmission control when the throughput monitoring result throughput is lower than a reference value, Retransmission control starting means for starting retransmission control when the value is restored to a value better than the reference value.

In the error control system for a wireless data link layer according to a ninth aspect, the retransmission control stopping means stops the retransmission control when the transmission throughput of the radio section has deteriorated below the first reference value, and starts the retransmission control. Starts retransmission control when the transmission throughput of the wireless section exceeds a second reference value better than the first reference value.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a flow of a transmission operation of the wireless data link layer of the error control method according to the present embodiment. A when ARQ control is stopped
When the RQ start request is received, an ARQ start response is transmitted, and A
RQ control is started. If the ARQ start request is not received when the ARQ control is stopped, the ARQ control is not performed. At this time,
If there is new data, new transmission data is transmitted. If there is no new data, the transmission is stopped. When the ARQ stop request is received during the execution of the ARQ control, an ARQ stop response is transmitted, and the ARQ control is stopped. ARQ when executing ARQ control
If the stop request is not received, the operation is similar to the transmission operation of the wireless data link layer shown in FIG.

The reception operation of the wireless data link layer in the present embodiment will be described with reference to FIG. When the ARQ start response is received when the ARQ control is stopped, the ARQ control is started. At this time, when the deterioration of the wireless link condition is detected, ARQ is performed.
Send a stop request. If the state of the wireless link is not degraded, the operation is the same as the reception operation of the wireless data link layer shown in FIG. If the ARQ start response is not received when the ARQ control is stopped, the recovery of the wireless channel state is monitored. here,
When detecting the recovery of the wireless channel state, the mobile station transmits an ARQ start request. When the ARQ stop response is received during the execution of the ARQ control, the ARQ control is stopped, and the recovery of the radio link state is monitored. Here, when the recovery of the wireless channel state is detected, an ARQ start request is transmitted. A during ARQ control
If the RQ stop response is not received, the deterioration of the wireless channel state is monitored. When the deterioration of the wireless link condition is detected, ARQ
Send a stop request. If the state of the wireless link is not degraded, the operation is the same as the reception operation of the wireless data link layer shown in FIG.

FIG. 3 shows the state transition of the error control system in the upper layer and the wireless data link layer of the present embodiment. In the figure, state 1 indicates a state in which the radio link condition is good, and state 2 indicates a state in which the radio link condition has deteriorated. In the state 1 in which the wireless channel state is good, ARQ control is performed for both the upper layer and the wireless data link layer. When the state of the wireless link deteriorates below the reference value, the state shifts to state 2. In state 2, only upper layer AR
Q control is performed, and ARQ control is not performed in the wireless data link layer. When the state of the wireless link recovers to a value better than the reference value, the state shifts to state 1.

FIG. 4 shows an example of ARQ control according to the present embodiment. The crosses in the figure indicate poor reception. Also, N
(A3) indicates a retransmission request for data a3. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. Upper layer A
Then, the divided data is assembled again and the data is reproduced. Further, when a reception failure occurs in the wireless packet a3, the wireless data link layer A returns a retransmission request for the wireless packet a3 to the wireless data link layer B. The wireless data link layer B retransmits the wireless packet requested by the retransmission request. Up to this point, it is the same as FIG. In FIG. 4, when the wireless data link layer A detects that the line condition has deteriorated from the reference value, the wireless data link layer B
Send a Q stop request. Wireless data link layer B is ARQ
Upon receiving the stop request, the mobile station returns an ARQ stop response and stops ARQ control in the wireless data link layer. After this,
If an error occurs in data transmission between the upper layer C and the upper layer A, the error is recovered by ARQ control in the upper layer, including an error that has occurred on the radio link. The wireless data link layer A monitors the state of the wireless link even when the ARQ control is stopped, and transmits an ARQ start request to the wireless data link layer B when detecting that the link state has recovered to a value better than the reference value. Upon receiving the ARQ start request, the wireless data link layer B returns an ARQ start response, and starts ARQ control in the wireless data link layer. As described above, this embodiment can be realized without changing the existing upper layer ARQ control protocol.

FIG. 5 shows an example of the transmission throughput characteristic in the upper layer in this embodiment. In the figure, the thin solid line shows the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer, and the broken line shows that the ARQ control is performed only for the upper layer.
This is a throughput characteristic when Q control is not performed. The thick solid line indicates the throughput characteristic in the present embodiment. The ARQ control in the wireless data link layer has a smaller round-trip delay and, therefore, can be efficiently retransmitted (1).
Perform Q control. Thereafter, if the state of the wireless link further deteriorates, there is a possibility that the ARQ control in the upper layer and the ARQ control in the wireless data link layer may become inconsistent, so the ARQ control in the wireless data link layer is stopped.

Embodiment 2 FIG. The reception operation of the wireless data link layer in the present embodiment will be described with reference to FIG. The transmission operation is the same as in FIG. ARQ
When the ARQ start response is received during the control stop, the ARQ control is started. At this time, when it is sensed that the BER has degraded from the reference value, an ARQ stop request is transmitted. If the BER is better than the reference value, the operation is the same as the reception operation of the wireless data link layer shown in FIG. A when ARQ control is stopped
If the RQ start response is not received, the recovery of the BER characteristic is monitored. Here, when it is detected that the BER has become better than the reference value, an ARQ start request is transmitted. AR
When the ARQ stop response is received during the execution of the Q control, the ARQ control is stopped and the recovery of the BER characteristic is monitored. Here, when it is detected that the BER has recovered to a value better than the reference value, an ARQ start request is transmitted. If the ARQ stop response is not received at the time of executing the ARQ control, the BER characteristic is monitored for deterioration. When detecting that the BER has degraded from a reference value, it transmits an ARQ stop request. If the BER characteristic has not deteriorated, the operation is the same as the reception operation of the wireless data link layer shown in FIG.

FIG. 7 shows an example of ARQ control in the present embodiment. The crosses in the figure indicate poor reception. Also, N
(A3) indicates a retransmission request for data a3. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. Upper layer A
Then, the divided wireless packets are reassembled and the data is reproduced. When a reception failure occurs in the wireless packet a3, the wireless data link layer A becomes the wireless data link layer B.
, A retransmission request for the wireless packet is returned. The wireless data link layer B retransmits the wireless packet requested by the retransmission request. Up to this point, it is the same as FIG. FIG.
When the wireless data link layer A detects that the BER characteristic has deteriorated below the reference value, the wireless data link layer A transmits an ARQ stop request to the wireless data link layer B. Wireless data link layer B is A
When the RQ stop request is received, an ARQ stop response is returned, and ARQ control in the wireless data link layer is stopped. Thereafter, when an error occurs in data transmission between the upper layer C and the upper layer A, the error is recovered by ARQ control in the upper layer, including an error generated on the radio line. The wireless data link layer A monitors the BER characteristics even when the ARQ control is stopped, and transmits an ARQ start request to the wireless data link layer B when detecting that the BER characteristics have recovered to a value better than the reference value. Upon receiving the ARQ start request, the wireless data link layer B returns an ARQ start response, and starts ARQ control in the wireless data link layer. As explained above,
In the present embodiment, the present invention can be realized without changing the existing upper layer ARQ control protocol.

FIG. 8 shows an example of the transmission throughput characteristic in the upper layer according to the present embodiment. In the figure, the thin solid line shows the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer, and the broken line shows that the ARQ control is performed only for the upper layer.
This is a throughput characteristic when Q control is not performed. The thick solid line indicates the throughput characteristic in the present embodiment. The ARQ control in the wireless data link layer has a smaller round-trip delay and, therefore, can be efficiently retransmitted (1).
Perform Q control. After that, if the BER characteristic further deteriorates, there is a possibility that the ARQ control in the upper layer and the ARQ control in the wireless data link layer may be inconsistent, so the ARQ control in the wireless data link layer is stopped.

Embodiment 3 In the present embodiment, as shown in FIG. 9, a reference value for determining BER characteristic recovery is set to a better BER value than a reference value for determining BER characteristic deterioration. As a result, a hysteresis effect occurs, and it is possible to suppress the operation of repeatedly stopping and starting ARQ control that occurs when the BER characteristic fluctuates near the reference value in the second embodiment.

Embodiment 4 The reception operation of the wireless data link layer in the present embodiment will be described using FIG. The transmission operation is the same as in FIG. AR
When the ARQ start response is received when the Q control is stopped, the ARQ control is started. At this time, when it is detected that the PER has deteriorated from the reference value, an ARQ stop request is transmitted. If the PER has not deteriorated from the reference value, the operation is the same as the reception operation of the wireless data link layer shown in FIG. If the ARQ start response is not received when the ARQ control is stopped, the recovery of the PER characteristic is monitored. Here, when it is detected that the PER has recovered to a value better than the reference value, an ARQ start request is transmitted. When an ARQ stop response is received during the execution of the ARQ control, the ARQ control is stopped and the recovery of the PER characteristic is monitored. Here, when it is detected that the PER has recovered to a value better than the reference value, an ARQ start request is transmitted. A
If an ARQ stop response is not received when executing RQ control, P
Monitor the deterioration of the ER characteristic. When detecting that the PER has degraded from a reference value, it transmits an ARQ stop request. P
If the ER characteristics have not deteriorated, the operation is the same as the reception operation of the wireless data link layer shown in FIG.

FIG. 11 shows an example of ARQ control according to the present embodiment. The crosses in the figure indicate poor reception. Also, N
(A3) indicates a retransmission request for data a3. The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the wireless packets received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided wireless packets and reproduces the data. Further, when a reception failure occurs in the wireless packet a3, the wireless data link layer A returns a retransmission request for the wireless packet already transmitted to the wireless data link layer B. The wireless data link layer B retransmits the wireless packet requested by the retransmission request. Up to this point, it is the same as FIG. In FIG. 4, when the wireless data link layer A senses that the PER characteristic has deteriorated from the reference value, it transmits an ARQ stop request to the wireless data link layer B. Upon receiving the ARQ stop request, the wireless data link layer B returns an ARQ stop response, and stops ARQ control in the wireless data link layer. Thereafter, when an error occurs in data transmission between the upper layer C and the upper layer A, the error is recovered by ARQ control in the upper layer, including an error generated on the radio line. Wireless data link layer A is PER even when ARQ control is stopped
When the PER characteristic is monitored to recover to a value better than the reference value, the ARQ is transmitted to the wireless data link layer B.
Send a start request. Upon receiving the ARQ start request, the wireless data link layer B returns an ARQ start response, and starts ARQ control in the wireless data link layer. As described above, this embodiment can be realized without changing the existing upper layer ARQ control protocol.

FIG. 12 shows an example of transmission throughput characteristics in the upper layer according to the present embodiment. In the figure, a thin solid line indicates the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer, and a broken line indicates that ARQ control is performed only for the upper layer, and A in the wireless data link layer.
This is a throughput characteristic when RQ control is not performed. The thick solid line indicates the throughput characteristic in the present embodiment. The ARQ control in the wireless data link layer has a smaller round-trip delay and, therefore, can be efficiently retransmitted (1).
Perform Q control. After that, if the PER characteristic further deteriorates, there is a possibility that the ARQ control in the upper layer and the ARQ control in the wireless data link layer may become inconsistent, so the ARQ control in the wireless data link layer is stopped.

Embodiment 5 In the present embodiment, as shown in FIG.
The PER value is set to a better value than the reference value for determining the characteristic deterioration. As a result, a hysteresis effect occurs, and it is possible to suppress the operation of repeating ARQ control stop / start that occurs when the PER characteristic fluctuates near the reference value in the fourth embodiment.

Embodiment 6 FIG. The reception operation of the wireless data link layer in the present embodiment will be described using FIG. The transmission operation is the same as in FIG. ARQ
When the ARQ start response is received during the control stop, the ARQ control is started. At this time, when it is detected that the received signal level is lower than the reference value, the ARQ stop request is transmitted. If the received signal level is not degraded from the reference value, FIG.
The operation is the same as the reception operation of the wireless data link layer shown in FIG. If the ARQ start response is not received when the ARQ control is stopped, the recovery of the received signal level is monitored. Here, when it is detected that the received signal level has recovered to a value better than the reference value, an ARQ start request is transmitted. When an ARQ stop response is received during the execution of the ARQ control, the ARQ control is stopped and the recovery of the received signal level is monitored. Here, when it is detected that the received signal level has recovered to the reference value or higher, an ARQ start request is transmitted. A during ARQ control
If the RQ stop response is not received, the deterioration of the received signal level is monitored. When detecting that the received signal level has degraded from the reference value, it transmits an ARQ stop request. If the received signal level has not deteriorated, the operation is the same as the reception operation of the wireless data link layer shown in FIG.

FIG. 15 shows an example of ARQ control according to the present embodiment. The crosses in the figure indicate poor reception. Also, N
(A3) indicates a retransmission request for the wireless packet a3.
The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided data and reproduces the data. When a reception failure occurs in the wireless packet a3, the wireless data link layer A becomes the wireless data link layer B.
Returns a retransmission request for the already-received wireless packet. The wireless data link layer B retransmits the wireless packet requested by the retransmission request. Up to this point, it is the same as FIG. In FIG. 4, when the wireless data link layer A detects that the received signal level has degraded from the reference value, the wireless data link layer B
To the ARQ stop request. Upon receiving the ARQ stop request, the wireless data link layer B returns an ARQ stop response,
ARQ control in the wireless data link layer is stopped. Thereafter, when an error occurs in data transmission between the upper layer C and the upper layer A, including an error occurring on the radio line,
The error is recovered by the ARQ control in the upper layer. The wireless data link layer A monitors the received signal level even when the ARQ control is stopped, and when it detects that the received signal level has recovered to a value better than the reference value, the wireless data link layer B sends the ARQ to the wireless data link layer B.
Send a start request. Upon receiving the ARQ start request, the wireless data link layer B returns an ARQ start response, and starts ARQ control in the wireless data link layer. As described above, this embodiment can be realized without changing the existing upper layer ARQ control protocol.

FIG. 16 shows an example of transmission throughput characteristics in the upper layer according to the present embodiment. In the figure, a thin solid line indicates the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer, and a broken line indicates that ARQ control is performed only for the upper layer, and A in the wireless data link layer.
This is a throughput characteristic when RQ control is not performed. The thick solid line indicates the throughput characteristic in the present embodiment. The ARQ control in the wireless data link layer has a smaller round-trip delay and, therefore, can be efficiently retransmitted (1).
Perform Q control. After that, if the received signal level further deteriorates, there is a possibility that the ARQ control in the upper layer and the ARQ control in the wireless data link layer may become inconsistent, so the ARQ control in the wireless data link layer is stopped.

Embodiment 7 FIG. In the present embodiment, as shown in FIG. 17, the reference value for determining the recovery of the received signal level is set to a better received signal level value than the reference value for determining the degradation of the received signal level. As a result, a hysteresis effect occurs, and it is possible to suppress the operation of repeatedly stopping / starting ARQ control that occurs when the received signal level fluctuates near the reference value in the sixth embodiment.

Embodiment 8 The reception operation of the wireless data link layer in this embodiment will be described with reference to FIG. The transmission operation is the same as in FIG. ARQ
When the ARQ start response is received during the control stop, the ARQ control is started. At this time, when it is detected that the transmission throughput has deteriorated from the reference value of the wireless section, an ARQ stop request is transmitted. If the transmission throughput in the wireless section has not deteriorated from the reference value, the operation is the same as the reception operation of the wireless data link layer shown in FIG. If the ARQ start response is not received when the ARQ control is stopped, the recovery of the transmission throughput in the wireless section is monitored. Here, when it is detected that the transmission throughput of the wireless section has been restored to a value better than the reference value, an ARQ start request is transmitted. A during ARQ control
Upon receiving the RQ stop response, the ARQ control is stopped, and the recovery of the transmission throughput in the wireless section is monitored. Here, when it is detected that the transmission throughput of the wireless section has recovered to a reference value or more, an ARQ start request is transmitted. ARQ
If an ARQ stop response is not received at the time of executing the control, deterioration of the transmission throughput in the wireless section is monitored. When it is detected that the transmission throughput of the wireless section has degraded from a reference value, an ARQ stop request is transmitted. If the transmission throughput of the wireless section has not deteriorated, the operation is the same as the reception operation of the wireless data link layer shown in FIG.

FIG. 19 shows an example of ARQ control in the present embodiment. The crosses in the figure indicate poor reception. Also, N
(A3) indicates a retransmission request for the wireless packet a3.
The data a in the upper layer C is divided by the wireless data link layer B into wireless packets a1, a2, and a3 and transmitted to the wireless data link layer A. In the wireless data link layer A, the data received without error are sequentially delivered to the upper layer A. The upper layer A reassembles the divided data and reproduces the data. When a reception failure occurs in the wireless packet a3, the wireless data link layer A becomes the wireless data link layer B.
Returns a retransmission request for the already-received wireless packet. The wireless data link layer B retransmits the wireless packet requested by the retransmission request. Up to this point, it is the same as FIG. FIG.
When the wireless data link layer A detects that the transmission throughput of the wireless section has deteriorated below the reference value, the wireless data link layer A transmits an ARQ stop request to the wireless data link layer B. Upon receiving the ARQ stop request, the wireless data link layer B returns an ARQ stop response, and stops ARQ control in the wireless data link layer. Thereafter, when an error occurs in data transmission between the upper layer C and the upper layer A, the error is recovered by ARQ control in the upper layer, including an error generated on the radio line. The wireless data link layer A monitors the transmission throughput in the wireless section even when the ARQ control is stopped, and when it detects that the transmission throughput in the wireless section has recovered to a value better than the reference value, it issues an ARQ start request to the wireless data link layer B. Send. Upon receiving the ARQ start request, the wireless data link layer B returns an ARQ start response, and starts ARQ control in the wireless data link layer. As described above, this embodiment can be realized without changing the existing upper layer ARQ control protocol.

FIG. 20 shows an example of transmission throughput characteristics in the upper layer according to the present embodiment. In the figure, a thin solid line indicates the throughput characteristics when ARQ control is performed for both the upper layer and the wireless data link layer, and a broken line indicates that ARQ control is performed only for the upper layer, and A in the wireless data link layer.
This is a throughput characteristic when RQ control is not performed. The thick solid line indicates the throughput characteristic in the present embodiment. The ARQ control in the wireless data link layer has a smaller round-trip delay and, therefore, can be efficiently retransmitted (1).
Perform Q control. After that, if the transmission throughput in the wireless section further deteriorates, there is a possibility that the ARQ control in the upper layer and the ARQ control in the wireless data link layer may become inconsistent, so the ARQ control in the wireless data link layer is stopped.

Embodiment 9 FIG. In the present embodiment, as shown in FIG. 21, the reference value for determining the transmission throughput recovery in the wireless section is set to a better transmission throughput value for the wireless section than the reference value for determining the transmission throughput degradation in the wireless section. Is what you do. As a result, a hysteresis effect occurs, and it is possible to suppress the operation of repeatedly stopping and starting ARQ control that occurs when the transmission throughput of the wireless section fluctuates near the reference value in the eighth embodiment.

[0046]

According to the first aspect of the present invention, when the line condition deteriorates, the upper layer performs ARQ control and the radio data link layer performs AR control.
Since the Q control is stopped, the throughput of the line is improved, and an increase in delay can be suppressed. Further, the throughput of the line can be improved without changing the existing upper layer protocol.

According to a second aspect of the present invention, when the BER characteristic is degraded, the upper layer performs ARQ control, and the radio data link layer performs AR control.
Since the Q control is stopped, the throughput of the line is improved, and an increase in delay can be suppressed. Further, the throughput of the line can be improved without changing the existing upper layer protocol.

According to the third aspect of the present invention, since the reference value for judging the BER characteristic recovery is set to a value better than the reference value for judging deterioration, the ARQ control which occurs when the BER characteristic of the radio section fluctuates near the reference value. The operation of repeating stop / start can be suppressed.

According to a fourth aspect of the present invention, when the PER characteristic deteriorates, the upper layer performs ARQ control, and the radio data link layer performs AR control.
Since the Q control is stopped, the throughput of the line is improved, and an increase in delay can be suppressed. Further, the throughput of the line can be improved without changing the existing upper layer protocol.

According to the fifth aspect of the present invention, the reference value for judging the recovery of the PER characteristic is set to a value better than the reference value for judging the deterioration. The operation of repeating stop / start can be suppressed.

According to a sixth aspect of the present invention, when the received signal level is deteriorated, the upper layer performs ARQ control and the wireless data link layer stops ARQ control, thereby improving the throughput of the line and suppressing the increase in delay. it can. Further, the throughput of the line can be improved without changing the existing upper layer protocol.

According to the seventh aspect, the reference value for judging the recovery of the received signal level is set to a value better than the reference value for judging the deterioration. / Repeating the start operation can be suppressed.

According to the eighth aspect, when the transmission throughput is deteriorated, the upper layer performs ARQ control and the wireless data link layer stops ARQ control, so that the throughput of the line is improved. Further, the throughput of the line can be improved without changing the existing upper layer protocol.

According to the ninth aspect of the present invention, the reference value for judging the recovery of the transmission throughput in the radio section is set to a value better than the reference value for judging the deterioration. It is possible to suppress the operation of repeating the ARQ control stop / start that occurs.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flow of a transmission operation of a wireless data link layer of an error control method according to a first embodiment.

FIG. 2 is a diagram showing a reception operation of a wireless data link layer according to the first embodiment.

FIG. 3 is a diagram showing a state transition of an error control method in an upper layer and a wireless data link layer according to the first embodiment.

FIG. 4 is a diagram showing an example of ARQ control according to the first embodiment.

FIG. 5 is a diagram illustrating an example of a transmission throughput characteristic according to the first embodiment.

FIG. 6 is a diagram illustrating a reception operation of a wireless data link layer according to a second embodiment.

FIG. 7 is a diagram illustrating an example of ARQ control according to a second embodiment.

FIG. 8 is a diagram illustrating an example of a transmission throughput characteristic according to the second embodiment.

FIG. 9 is a diagram in which a reference value for judging BER characteristic recovery is a value better than a reference value for judging deterioration.

FIG. 10 is a diagram illustrating a reception operation of a wireless data link layer according to a fourth embodiment.

FIG. 11 is a diagram illustrating an example of ARQ control according to a fourth embodiment.

FIG. 12 is a diagram illustrating an example of a transmission throughput characteristic according to the fourth embodiment.

FIG. 13 is a diagram in which a reference value for determining PER characteristic recovery is a value better than a reference value for determining deterioration.

FIG. 14 is a diagram illustrating a reception operation of a wireless data link layer according to a sixth embodiment.

FIG. 15 is a diagram illustrating an example of ARQ control according to a sixth embodiment.

FIG. 16 is a diagram illustrating an example of a transmission throughput characteristic according to the sixth embodiment.

FIG. 17 shows a reference value for judging recovery of a received signal level,
It is the figure which made the value better than the reference value which judges deterioration.

FIG. 18 is a diagram illustrating a reception operation of the wireless data link layer according to the eighth embodiment.

FIG. 19 is an example of ARQ control according to the eighth embodiment.

FIG. 20 is an example of transmission throughput characteristics according to the eighth embodiment.

FIG. 21 is a diagram in which a reference value for judging recovery of transmission throughput in a wireless section is a value better than a reference value for judging deterioration.

FIG. 22 is a diagram illustrating an example of a protocol stack in data communication.

FIG. 23 shows a conventional AR between an upper layer A and an upper layer C;
It is a figure which shows the transmission operation | movement of Q control.

FIG. 24 shows a conventional AR between an upper layer A and an upper layer C;
It is a figure which shows the reception operation | movement of Q control.

FIG. 25 is a diagram showing ARQ control between a conventional wireless data link layer A and a conventional wireless data link layer B.

FIG. 26 shows a conventional AR between an upper layer A and an upper layer C;
It is a figure which shows the reception operation | movement of Q control.

FIG. 27 is a diagram illustrating an example of normal ARQ control.

FIG. 28 is a diagram illustrating an example of a case where an error occurs in a relatively good wireless channel state.

FIG. 29 is a diagram illustrating an example of a case where an error occurs in a state where a wireless channel state is deteriorated.

FIG. 30 shows a case where A is added to the conventional upper layer and wireless data link layer.
FIG. 9 is a diagram illustrating an example of a transmission throughput characteristic when RQ control is applied.

[Explanation of symbols]

 a, b, c Upper layer data a1, a2, a3, b1, b2, b3, wireless packet N (a3) Request for retransmission of wireless packet a3

Claims (9)

[Claims] A line state monitoring means for monitoring a line state in a wireless data link layer error control system in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on a wireless data link layer. Retransmission control stopping means for stopping retransmission control when the line condition monitoring result is degraded from a reference value; retransmission control starting means for starting retransmission control when the line condition monitoring result is restored to a value better than the reference value And a wireless data link layer error control method. 2. An error control method for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on a wireless data link layer, wherein a line state is determined by a bit error rate (Bit Error Rate).
e: BER) monitoring means, BER monitoring means, retransmission control stopping means for stopping retransmission control when the BER monitoring result BER is lower than a reference value, and recovering the BER monitoring result BER to a value better than the reference value. And a retransmission control start means for starting retransmission control if necessary. 3. The retransmission control stopping means stops retransmission control if the BER is degraded from a first reference value, and the retransmission control starting means stops the retransmission control when the BER is better than the first reference value.
3. The wireless data link layer error control method according to claim 2, wherein the retransmission control is started when the reference value is exceeded. 4. An error control system for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on a wireless data link layer, wherein a line state is determined by a data block per predetermined time. PER monitoring means for monitoring by the number of errors (Packet Error Rate: PER); retransmission control stopping means for stopping retransmission control when the PER monitoring result PER is degraded from a reference value; and when the PER monitoring result PER is higher than the reference value. And a retransmission control start means for starting retransmission control when the value has been restored to a good value. 5. The retransmission control stopping means stops retransmission control if the PER has degraded from a first reference value, and the retransmission control starting means has a second PER with a better PER than the first reference value.
5. The error control method of the wireless data link layer according to claim 4, wherein the retransmission control is started when the reference value exceeds the reference value. 6. An error control system for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on a wireless data link layer, wherein a line state is monitored by a received signal level. Signal level monitoring means; retransmission control stopping means for stopping retransmission control when the received signal level monitoring result received signal level is degraded from a reference value; and a value at which the received signal level monitoring result received signal level is better than the reference value. And a retransmission control start means for starting retransmission control when the error has been recovered. 7. The retransmission control stopping means stops retransmission control when a received signal level is degraded from a first reference value, and the retransmission control starting means stops the retransmission control when the received signal level is higher than the first reference value. 7. The error control method of the wireless data link layer according to claim 6, wherein retransmission control is started when the reference value exceeds 2. 8. An error control method for a wireless data link layer in data transmission between a transmitting and receiving station having an upper layer for performing retransmission control on a wireless data link layer, wherein a line state is monitored by a transmission throughput in a wireless section. A retransmission control stopping means for stopping retransmission control if the throughput monitoring result throughput is degraded from a reference value, and starting a retransmission control if the throughput monitoring result throughput is restored to a value better than the reference value. Error control method for the wireless data link layer, comprising: 9. The retransmission control stopping means stops retransmission control if the transmission throughput of the radio section is degraded from a first reference value, and the retransmission control start means sets the transmission throughput of the radio section to the first reference value. 9. The wireless data link layer error control method according to claim 8, wherein the retransmission control is started when the value exceeds a better second reference value.