JP2000216813A - Error compensation method and error compensation device using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cancel a packet where excessive delay time occurs by managing it to be a transmission abnormal state that delay time is a prescribed value, ignoring the retransmission request of the packet in control information while the state is restored to normal one and sequentially transmitting the packets which are in the middle of accumulation and whose normal reception is not recognized yet. SOLUTION: Delay time is managed by using a time stamp shown by the repetition of a value from '0' to M-1 as a modulo M. Delay time δT obtained from a difference between the input time of a packet and present time takes an integer value from '0' to M-1. When δT becomes TI>=δ>=0 against a prescribed threshold T1, delay time is considered to be an allowable value and retransmission control for compensating an error by retransmission is executed on the packet where the code error occurs as a normal state. When the abnormality of a delay state where δT exceeds the threshold and becomes δT<=T1 is detected, the transmission state is considered to be abnormal and is managed. Retransmission control is temporarily stopped and the transmission of the packet in a transmission buffer is speedily completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system and a communication apparatus for continuously transmitting packets and continuously communicating in a system for connecting a transmitting station and a receiving station via a wire or wirelessly. The present invention relates to a technique for compensating for a code error by retransmitting the packet when the code error occurs on a road. The present invention is used particularly in a wireless communication system such as a wireless ATM.

[0002]

2. Description of the Related Art In a wireless ATM, an ATM cell requiring high transmission quality is transferred through a radio channel having a severe propagation environment. In particular, in services that require real-time properties in addition to low cell loss rate characteristics, code errors that occur in the radio section are limited to the radio section and efficiently and promptly retransmitted to compensate for the error. There is a need to.

As a retransmission control method, a sequence number, which is a serial number, is assigned to a fixed-length packet to be transferred,
The receiving station notifies the transmitting station of the sequence number of the packet received without any code error, or notifies the sequence number of the next packet expected to be received from the continuity of the sequence numbers as control information relating to the retransmission request. On the other hand, the transmitting station determines the next packet to be transmitted based on this information.

FIG. 13 shows a processing flow at the time of receiving control information on the transmitting station side in the conventional system. Upon receiving the control information necessary for retransmission control (S100), the transmitting station searches the control information for a packet that has not been normally received by the receiving station, and determines a packet to be transmitted next (S101). The process ends (S102).

FIG. 14 shows a processing flow at the time of packet reception on the receiving station side in the conventional system. Upon receiving the packet (S103), the receiving station checks whether there is any code error in the packet (S104). If there is no code error, the receiving station acquires the sequence number RSN assigned to the received packet (S105), The arrival of the packet with the sequence number RSN is recorded in the reception status management table that manages the
106), the packet is stored in the reception buffer (S107), and the process ends (S109). If a code error is detected (S104), the packet is discarded (S108), and the process ends (S109).

FIG. 15 shows a processing flow at the time of transmitting control information of a receiving station in the conventional system. When receiving the control information transmission instruction (S110), the receiving station refers to the reception state management table, generates retransmission request information notifying the reception state of the packet on the receiving station side (S111), and transmits the retransmission request information. The stored control information is transmitted (S112), and the process ends (S113).

[0007] There are various ways of describing retransmission request information depending on the system, such as Go Back N (GBN) system, Selective Repeat.
A method such as the (SR) method is widely used. In the case of the SR method, when the receiving station successfully receives a packet, the receiving station returns an acknowledgment (ACK) signal indicating normal reception to the transmitting station, and the transmitting station selects only the packet for which the ACK was not received. And resend. In this case, the management of the arrival state for each packet is performed on the transmitting station side, and the receiving station does not need to manage the packet receiving state. However, in the case of the GBN system, the receiving station monitors the continuity of the sequence number assigned to the normally received packet, and in the case of discontinuity, identifies the missing sequence number as a negative acknowledgment.
This is notified as edgement (NAK), and requests retransmission of the packet.

FIG. 16 shows a functional block diagram of an error compensating apparatus on the transmitting station side in the conventional system. In the figure, 101 is a sequence number assignment circuit, 102 is a transmission buffer, 103 is a transmission packet management circuit, 104 is a control information reception circuit, and 105 is an error detection code assignment circuit.

When a packet is input to the sequence number assigning circuit 101, a sequence number, which is a serial number, is assigned to the packet, and is temporarily stored in the transmission buffer 102. In the transmission packet management circuit 103, the control information receiving circuit 1
Based on the retransmission request information in the control information received at 04,
Next, a packet to be transmitted is determined, and a transmission instruction is issued together with the sequence number of the packet to be transmitted to the transmission buffer 102 at the packet transmission timing. A packet output from the transmission buffer 102 is further provided with a code error detection code by an error detection code providing circuit 105, and the packet is transmitted.

FIG. 17 shows a functional block diagram of an error compensating device on the receiving station side in the conventional system. In the figure, 106 is a code error detection circuit, 107 is a control information transmission circuit, 108 is a reception state management table, 109 is a sequence number reference circuit, 110
Denotes a packet output control circuit, and 111 denotes a reception buffer.

When a receiving station receives a packet, it first detects a code error in a code error detection circuit 106, and if a code error is detected in the packet, discards the packet. On the other hand, the packet having no code error is transferred to the sequence number reference circuit 109, and the sequence number of the normally received packet acquired by the sequence number reference circuit 109 is output to the reception state management table 108, and is temporarily stored in the reception buffer 111. You. The reception state management table 108 manages the sequence numbers of successfully received packets, checks the continuity of the sequence numbers, and searches for the sequence numbers of the missing packets. Note that once the receive buffer
The packet accommodated in 111 is transmitted to a packet output control circuit 110.
Is output at an appropriate timing in accordance with the instruction.

[0012]

In a high-speed communication system, such as a wireless ATM, in which a large amount of short packets must be processed in a short time, simple processing is required for error compensation by retransmission. ing. The SR method generally has a large amount of processing, and therefore, for the wireless ATM, the GBN method and Japanese Patent Application Laid-Open No. H10-117182 entitled "Error Compensation Method and Apparatus and Medium Stored with Error Compensation Program" by the same inventor are suitable. However, in these systems, the receiving side monitors the continuity of the sequence number assigned to the received packet, and if any sequence number that has not been received is detected, an infinite number of retransmission requests are made. Will be.

On the other hand, in the wireless ATM, services requiring real-time properties are also handled, so that a packet whose transmission delay time has exceeded a certain value may be discarded on the transmission side while avoiding excessive retransmissions. preferable. In fact, in a wireless environment, it is easy for the transmission quality to rapidly deteriorate due to shadowing, fading, and the like. However, in a system using the GBN scheme or the like, when a packet on which excessive delay has occurred is discarded on the transmitting side, it is difficult for the receiving side to recognize this situation and continue processing.

In the case of the SR system, unlike the GBN system or the like, even if a packet on which excessive delay has occurred is discarded on the transmitting side, there is no problem that the receiving side requires infinite retransmission. In other words, it is possible to measure the delay time for each packet on the transmitting side and cancel transmission of the packet in which excessive delay has occurred. In this case, the transmitting station is required to have a time stamp counter for managing the current time, refer to a time stamp counter value when a packet is input, and record the value in association with the packet.

FIG. 18 shows a processing flow for discarding a packet in which an excessive delay has occurred on the transmitting station side. When there is a packet transmission instruction in the transmitting station (S114), a packet to be transmitted next is searched (S115), and the delay time is measured (calculated) from the difference between the input time of the packet and the current time (S116). Then, it is determined whether the delay time is within a predetermined allowable value (S117). If the allowable delay has been exceeded (S117), the packet is discarded (S118), and the process returns to the search for the next packet to be transmitted (S115). On the other hand, when the delay time is within the allowable value (S117), the packet is transmitted (S119), and a series of processing ends (S120).

In this processing flow, if the state in which the determination result is No in the condition determination in S117 continues for reasons such as shadowing, etc., S115 → S116 → S117 → S118 → S115
Is repeated, and depending on the number of loops, the search for the packet to be transmitted may not be completed by the predetermined packet transmission timing. Further, since the maximum number of processing loops is not deterministic, it is difficult to realize the processing by hardware processing without software, and as a result, it is not suitable for a wireless ATM transmission station apparatus requiring high-speed processing.

Accordingly, an object of the present invention is to enable a transmitting station to discard a packet having an excessive delay time even when managing a packet to be retransmitted on a receiving side such as a GBN system. An object of the present invention is to provide an error compensation method capable of easily realizing packet delay time management in the above method and an error compensation apparatus using the method.

[0018]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a system for continuously transmitting packets between a transmitting station and a receiving station via a wire or wirelessly. A sequence number is given, and the receiving station notifies the transmitting station of control information on the packet receiving state on the control line, and the transmitting station temporarily stores the input packet in a transmission buffer, and responds to the control information. In an error compensation method for retransmitting a packet or transmitting a new packet, the transmitting station includes a time stamp counter having a modulo M cycle for managing a current time,
The input time of the packet with the sequence number i is recorded together with the packet as a time stamp value TS (i), and the oldest packet whose normal reception at the receiving station has not been confirmed or transmitted at a predetermined period or at an appropriate timing is transmitted. The time stamp value TS (k) of the packet to be performed is obtained, and the delay time δT, which is the difference between the time stamp value TS (k) and the current time Tc, is calculated as δT = Tc−TS (k) or δT =
ΔT where M> δT ≧ 0 of Tc−TS (k) + M
When δT> T1 with respect to a predetermined threshold value T1 where M>T1> 0, the state is managed as a transmission abnormal state, and until the transmission state recovers to a normal state. Temporarily, ignoring the retransmission request for the packet described in the control information received from the receiving station, and transmitting the unacknowledged packet and the untransmitted new packet, which are stored in the transmission buffer and whose normal reception has not been confirmed, most frequently. Main features.

The conventional method extracts and inspects only the oldest packet whose normal reception at the receiving station has not been confirmed or the delay time of the packet scheduled to be transmitted from now on at a long cycle interval different from the packet transmission timing. As a result, the processing load on the transmitting station side is reduced, and
The difference is that high-speed processing can be realized by hardware processing by avoiding the repetition of the loop of S115 → S116 → S117 → S118 → S115 shown in FIG.

In the transmitting station, the input time of the packet having the sequence number i is determined by a time stamp value TS.
(I) is recorded together with the packet, and at a predetermined cycle or at an appropriate timing, the time stamp value TS (k) of the oldest packet whose normal reception at the receiving station has not been confirmed or the packet to be transmitted from now on is determined. The delay time δT, which is the difference between the time stamp value TS (k) and the current time Tc, is calculated as δT = Tc−TS (k) or δT = Tc−T
The delay time is calculated by δT that satisfies M> δT ≧ 0 of S (k) + M, and this delay time is a predetermined threshold T2 that satisfies M>T2> 0
If δT> T2, it is also preferable to discard all or a part of the unacknowledged packets and the unsent new packets accumulated in the transmission buffer.

This proposes a simple realizing method for quickly and quickly discarding packets having an excessive delay time accumulated in a buffer on the transmission side in a short time.

Further, the transmitting station notifies the receiving station of the transmission state of the transmitting station by adding a status indication bit indicating whether the transmission state is normal or abnormal to the packet and transmitting the packet. Is also preferred.

In addition, when the control information is transmitted from the receiving station to the transmitting station via the control line, the content of the transmission status indication bit added to the received packet is added to the control information to transmit the control information. At the transmitting station, the calculated delay time δT is δT> T1 or δT
When a delay abnormal state where T> T2 is once detected, state management is performed assuming that the transmission state is abnormal, and when the control information is received, determination of the return of the transmission state from the abnormal state to the normal state is made. Under the condition that the content of the transmission status indication bit added to the control information indicates an abnormality and the delay state has recovered to δT ≦ T1 and δT ≦ T2 at this time. It is also preferable to return to the normal state.

[0024] This is because even if an arbitrary packet is discarded as needed at the transmitting station side, errors due to retransmission by managing the receiving state of the packet at the receiving side such as the GBN system without stacking at the receiving side. It proposes a simple realization method applying a compensation method.

On the other hand, in order to realize all or a part of the above error compensation method on a device, in the present invention, in the transmitting station, a control information receiving circuit for receiving control information transmitted by the receiving station; A sequence number assigning circuit that assigns a sequence number to the input packet, a transmission buffer that stores the packet, a time stamp counter that manages the current time, and a time when the packet was input as a time stamp value along with the packet. A packet input time management circuit to manage, and calculate a delay time δt of a packet whose input time is the oldest at a predetermined cycle by a difference between a time stamp value t at the time of inputting the packet and a current time stamp value tc; A delay time determination circuit for determining whether or not this value is equal to or greater than a predetermined threshold T; and a transmission buffer to be initially transmitted or retransmitted. Packets are managed in the order of the oldest input time, and if the determination result from the delay time determination circuit is normal, a new transmission packet or a retransmission packet is selected according to the control information received by the control information reception circuit. In the meantime, if the determination result from the delay time determination circuit is abnormal, the retransmission request in the control information received by the control information receiving circuit is temporarily ignored and / or A transmission packet management circuit for discarding all or a part of the packets stored in the transmission buffer, and an error detection code adding circuit for adding an error detection code to the packet to be transmitted are provided.

The conventional device comprises: a delay time determining circuit for calculating a delay time δt of an oldest packet at a predetermined period and determining whether or not the input time is equal to or greater than a predetermined threshold T;
If the result of the determination from the delay time determination circuit is abnormal, the retransmission request in the received control information is temporarily ignored, or the transmission that discards all or part of the packets stored in the transmission buffer is performed. The difference is that a packet management circuit is provided.

Further, in the transmitting station, a control information receiving circuit for receiving control information transmitted by the receiving station, a sequence number assigning circuit for assigning a sequence number to the input packet, and a transmission buffer for accumulating the packet. A time stamp counter that manages the current time, a packet input time management circuit that manages the time when the packet was input as a time stamp value together with the packet,
Delay time δ of the packet whose input time is the oldest for each predetermined period
a delay time determining circuit that calculates t from the difference between the time stamp value t at the time of packet input and the current time stamp value tc, and determines whether the value is equal to or greater than a predetermined threshold T; A transmission state management circuit that determines whether the current transmission state is normal or abnormal based on the history of the determination result from the circuit and the control information received from the receiving station; and a packet in a transmission buffer to be initially transmitted or retransmitted. In the transmission state management circuit, if the transmission state is normal, select a new transmission packet or a retransmission packet according to the control information received by the control information reception circuit, and instruct output. On the other hand, if the transmission state is abnormal in the transmission state management circuit, temporarily ignore the retransmission request in the control information received by the control information receiving circuit and Or, a transmission packet management circuit for discarding all or a part of the packets stored in the transmission buffer, a transmission status indication bit adding circuit for adding a transmission status indication bit for indicating a current transmission status to the packet, and a packet to be transmitted. An error detection code adding circuit that adds an error detection code to the receiving station, the receiving station determines whether there is a code error in the received packet, and a code error detection circuit that discards the received packet when a code error is detected. A transmission status indication bit reference circuit that determines whether the display of the transmission status indication bit given to the normally received packet is normal or abnormal, and a sequence number reference circuit that acquires the sequence number given to the normally received packet. And recording the sequence number acquired by the sequence number reference circuit to determine the transmission state of the packet. And simultaneously manages the sequence number of the oldest packet that has not been normally received, and furthermore, if the acquired transmission status indication bit indicates an abnormality, the sequence number of the received packet is normally received. The reception state management table, which is managed by replacing with the oldest sequence number that has not been transmitted, and the reception state management table when transmitting the control information, refer to the reception state management table, A control information transmitting circuit for generating and transmitting control information including information indicating a packet expected to be received through the sequence number and the content of the transmission status indication bit assigned to the received packet. Is also preferred.

The conventional apparatus is different from the conventional apparatus in that the input time is the oldest packet delay time δt
And a delay time determination circuit for determining whether or not this value is equal to or greater than a predetermined threshold value T. A current transmission based on a history of determination results from the delay time determination circuit and control information received from the receiving station. A transmission state management circuit that determines whether the state is normal or abnormal, and whether the retransmission request in the control information received by the control information reception circuit is temporarily ignored when the transmission state is abnormal in the transmission state management circuit A transmission packet management circuit for discarding all or a part of the packets stored in the transmission buffer, and a transmission status indication bit addition circuit for adding a transmission status indication bit indicating the current transmission status to the packet, In the receiving station, a transmission status indication bit reference circuit for determining whether the display of the transmission status indication bit given to the normally received packet is normal or abnormal, and a transmission status table If the bit is not to display the abnormality, the reception state management table for managing replacement at the value of properly received and have not the oldest sequence number sequence number has been assigned to the received packet management values,
When transmitting control information, in addition to the conventional retransmission request information,
The difference is that a control information transmitting circuit for generating and transmitting control information including the content of the transmission status indication bit added to the received packet is provided.

In the present invention, the delay time of the oldest packet whose normal reception at the receiving station has not been confirmed or the packet scheduled to be transmitted from now on is sampled and inspected at intervals of a long cycle different from the packet transmission timing, When an excessive delay is detected, the error compensation by retransmission is temporarily suspended until the state is restored to a normal state, or a part or all of the packets in the transmission buffer are discarded. Therefore, it is possible to obtain an effect that the excess delay packet on the transmission side can be promptly discarded by simple control.

In the present invention, a transmission status indication bit is added to a packet to be transmitted, and the receiving side also has means for grasping the status of the transmitting side based on this information. Even if there is a packet whose retransmission has been unilaterally canceled, it is possible to obtain an effect that a stack of processing can be avoided in an error compensation method of managing the arrival state of the packet on the receiving side such as the GBN system.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing the operation in one embodiment of the present invention. In the present invention, the delay time is managed using a time stamp represented by repetition of a value from 0 to M-1 as the modulo M. The delay time δT obtained from the difference between the packet input time and the current time is from 0 to M−1
Take an integer value up to. When this δT becomes T1 ≧ δT ≧ 0 with respect to a predetermined threshold T1, the delay time is regarded as an allowable value, and retransmission control for performing error compensation by retransmission for a packet in which a code error has occurred is performed in a normal state. It is carried out as. On the other hand, if an abnormality in the delay state where δT exceeds the threshold and δT> T1 is detected, the transmission state is managed as abnormal,
The retransmission control is suspended, and the transmission of the packet in the transmission buffer is completed immediately. The suspension of the retransmission control means that the process proceeds assuming that all transmission packets have been normally received, regardless of the retransmission request in the control information transmitted from the receiving station.

Here, the abnormal state of the "transmission state" is different from the abnormal state of the "delay state" which simply means an instantaneous state, and the "transmission state" is determined by the history of the "delay state" in the past. You. Specifically, the transmission state transitions to the abnormal state by detecting the abnormality of the delay state once, but the condition for the transmission state to return from the abnormal state to the normal state includes the condition that the delay state is normal. In general, various conditions will be added. An example of the return condition is defined in claim 5.

FIG. 2 shows a flow of a delay state judging process according to an embodiment of the present invention. When a fixed-length packet (for example, an ATM cell) is used, packet arrival intervals vary depending on the transmission speed. For example, in order to achieve a transmission rate of 10 Mbit / s using ATM cells, the packet arrival interval is about 40 μsec. However, in the present invention, sampling inspection of the delay time of a packet is performed at a relatively long cycle different from the arrival intervals of these packets. In the processing flow of FIG. 2, when it is the sampling inspection timing of the delay time (S1), first, it is searched whether or not there is a packet whose transmission has not been completed in the transmission buffer (S2).
If there is an unsent packet, search for the packet with the oldest input time among unsent packets (S3).
The difference δT between the input time of the packet and the current time is taken (S4). When this δT is 0 or less (S5), δT is M
(S6) to calculate the delay time δT. The calculated delay time δT is compared with a predetermined threshold T1 (S7), and δT
If the value exceeds the threshold T1, the transmission state is managed as an abnormal state (S8), and the process is terminated (S9). Here, if there is no untransmitted packet in the condition determination S2, the processing is terminated without performing the above processing (S9).

FIG. 3 shows a processing flow at the time of receiving control information on the transmitting station side in one embodiment of the present invention. Unlike the processing flow of the conventional method shown in FIG. 13, when control information is received (S10), the transmission state described with reference to FIG. 2 is referred to, and when it is determined that the transmission state is abnormal (S11), The retransmission request information in the received control information is discarded (S12), and the process proceeds assuming that all subsequent transmission packets have been transmitted normally without a code error.
After that, the next packet to be transmitted is determined (S13),
A series of processing ends (S14).

FIG. 4 shows a flow of processing for determining a transmission state according to an embodiment of the present invention. At the delay sampling sampling timing (S15), the processing from S2 to S6 in FIG. 2 is executed to calculate the delay time δT of the oldest untransmitted packet, and this δT exceeds a predetermined threshold value T2. If it has been (S16), the transmission state is managed as an abnormal state (S8), the packet in the transmission buffer is discarded (S17), and a series of processing ends (S18). If δT is equal to or smaller than T2 in the condition determination S16, the packet is not discarded, and the process ends. The simplest example of the packet discarding process in process S17 is
This is to discard all the packets in the transmission buffer, but it is also possible to select and discard only some of the packets whose delay time has elapsed. By this processing, excess delay packets accumulated in the transmission buffer at the transmitting station due to shadowing or the like are discarded in a short time, and a valid packet input with a small delay time thereafter is promptly transmitted. Making it possible.

FIG. 5 is a conceptual diagram showing the operation of the third embodiment of the present invention. Here, the packet delay time δT is classified into three areas. When T1 ≧ δT ≧ 0, normal retransmission control is performed. When T2 ≧ δT> T1, retransmission control is temporarily stopped. Is large, and if δT> T2, part or all of the packets in the transmission buffer are discarded, and an attempt is made to quickly recover from the excessive delay occurrence state. This is a combination of the contents of claims 1 and 2, and the condition of T2> T1 is provided between the threshold values.

FIG. 6 shows a flow of a transmission state determination process according to an embodiment of the present invention. The processing from S2 to S8 is performed in the same manner as the processing in FIG. 2. After the processing in S8 in which the delay mode is managed as an abnormal state, it is determined whether or not the delay time δT exceeds the threshold T2 (S16). Only when the packet is present, the packet in the transmission buffer is discarded (S17), and a series of processing ends (S20).

In the above description, the process in which the communication state changes from normal to abnormal has been described. If Yes is selected in the condition determination of S7 of FIGS. 2 and 6 and S16 of FIG. 4, the system detects the delay abnormality and manages the transmission state as an abnormal state. Did not specify. Claims 4 and 5
Shows one method for performing recovery from the transmission state abnormality.

FIG. 7 shows a processing flow at the time of transmitting a packet according to an embodiment of the present invention. When receiving a packet transmission instruction (S21), the transmitting station searches for a packet to be transmitted (S22) and checks whether the transmission state is abnormal (S23). If the transmission state is abnormal, an abnormal state (for example, represented by "1") is added to the packet as a transmission state indication bit and the packet is transmitted (S25). If the transmission state is normal, the transmission state display bit is displayed. A normal (for example, represented by “0”) is added to the packet as a bit and transmitted (S24), and the process is terminated (S26).

FIG. 8 shows a processing flow at the time of receiving a packet in the receiving station according to one embodiment of the present invention. When the receiving station receives the packet (S27), it checks whether there is a code error (S28). If there is no code error, the receiving station refers to the sequence number of the received packet (S29). The packet of the RSN is treated as normal reception (S30). Further, referring to the transmission status indication bit, if an abnormal status is indicated (S31), all packets before the RSN are changed to normal reception handling (S32), and the last received transmission status indication bit is abnormal. Is managed (S33). On the other hand, condition judgment S31
If the transmission status indication bit of the received packet indicates normal, the management unit 209 manages the transmission status indication bit received last as normal (S34). Thereafter, the packet is stored in the reception buffer (S35), and the process is terminated (S35).
37). If a code error is detected in the first code error detection (S28), the packet is discarded (S3
6), end the processing (S37).

As in the conventional system shown in FIG. 15, the receiving station transmits control information to the transmitting station at an appropriate period. However, in the present invention according to claim 5, the control information is added to the retransmission request information in addition to the retransmission request information. , S33 or S34, and returns the status indication bit attached to the last received packet.

FIG. 9 shows a processing flow when control information is received by the transmitting station according to one embodiment of the present invention. When the control information is received (S38), the transmission state on the transmitting station side is checked first. If the transmission state is managed as abnormal (S39), whether the delay state is abnormal, that is, the last δT and T1 Alternatively, the result of the magnitude comparison with T2 is checked (S40). If the delay state is normal, it is checked whether the return value of the transmission status indicator bit contained in the received control information indicates an error (S41), and if the return value of the transmission status indicator bit is abnormal Then, the transmission state is returned from the abnormal state to the normal state (S42). If the result of the determination in either the condition determination S40 or S41 is No, the transmission state is not restored, and the retransmission request information in the control information is discarded as a transmission state abnormality (S43). If the transmission state on the transmitting station side is normal in the condition judgment S39, the processing from S40 to S43 is omitted. Through the above processing, the processing of the received control information is completed, a packet to be transmitted is determined thereafter (S44), and a series of processing ends.

FIG. 10 is a functional block diagram of a transmitting station side error compensator according to an embodiment of the present invention. In the figure, 1 is a sequence number assigning circuit, 2 is a time stamp counter, 3 is a packet input time management circuit, 4 is a delay state determination circuit, 5 is a transmission buffer, 6 is a transmission packet management circuit, 7 is a control information receiving circuit, Reference numeral 8 denotes an error code detection circuit.

When a packet is input to the transmitting station side error compensator, a sequence number SN, which is a serial number, is assigned to the packet by the sequence number assigning circuit 1, and the packet to which the sequence number is assigned is temporarily stored in the transmission buffer 5. Stored. At this time, the input of the packet with the sequence number SN is notified to the time stamp counter 2 that manages the current time, and the correspondence between the sequence number SN and the input time Tc is managed by the packet input time management circuit 3. On the other hand, the packet input to the transmission buffer 5 is managed by the transmission packet management circuit 6. When the transmitting station receives the control information returned from the receiving station, the control information receiving circuit 7 analyzes the content of the received control information and notifies the transmission packet management circuit 6 of retransmission request information and the like. The transmission packet management circuit 6 manages not only untransmitted packets but also transmission completed unacknowledged packets that may have been transmitted but may be retransmitted, and indicates normal reception of the packet included in the retransmission request information on the receiving station side. The management information of the communication state of the packet is updated with reference to the ACK signal or the NAK signal of the non-reception notification. Here, packets that are candidates for transmission or retransmission are managed in sequence number order. The delay state determination circuit 4 determines the delay state at a predetermined cycle. At the time of the determination, first, a packet that is a candidate for transmission or retransmission managed by the transmission packet management circuit 6 is transmitted. From the transmission packet management circuit 6. Then, the input time of the packet with this sequence number is called from the packet input time management circuit 3, the time is compared with the current time in the time stamp counter 2, and the determination result is notified to the transmission packet management circuit 6. The transmission packet management circuit 6 stops the retransmission control of the packet to be transmitted or discards the packet in the transmission buffer 5 when the transmission state abnormality is notified as a result of the determination.
To instruct. As a result of the above series of processing, the packet instructed to be transmitted by the transmission packet management circuit 6 is output from the transmission buffer 5, and the code error detection code adding circuit 8 adds the code error detection code to the packet. Is done.

Here, the packet input time management circuit 3 has a circuit configuration independent of the transmission buffer 5. However, depending on the system, a packet to be transmitted may be transferred with a time stamp added to the sequence number. In this case, the time stamp value may be collectively stored in the transmission buffer 5, and the packet input time management circuit 3 and the transmission buffer 5 may be combined.

The error compensator on the receiving side is shown in FIG.
The conventional type shown in FIG. 16 can be used.

FIG. 11 is a functional block diagram of the transmitting station side error compensating apparatus according to one embodiment of the present invention. In the figure, the circuits 1 to 8 are the same as those of FIG.
Has been added. The basic processing content is similar to that of FIG. 10, but the biggest difference is that the transmission state management circuit 10 does not directly notify the determination result of the delay state determination circuit 4 to the transmission packet management circuit 6 but the transmission state management circuit 10 The transmission state is controlled from the abnormal state by the content of the control information and the control information, and the transmission state is added to the packet by the transmission state display bit adding circuit 9 and transmitted. Details of this processing flow have been described with reference to FIGS. Note that the control information receiving circuit 11 in FIG.
In addition to the function of the control information receiving circuit 7, the function of extracting the return value of the transmission status indication bit from the control information and notifying the transmission status management circuit 10 is added.

FIG. 12 is a functional block diagram of the receiver-side error compensator according to an embodiment of the present invention. In the figure, 12 is a code error detection circuit, 13 is a transmission state indication bit reference circuit, 14 is a sequence number reference circuit, 15
Indicates a reception state management table, 16 indicates a control information transmission circuit, 17 indicates a reception buffer, and 18 indicates a packet output control circuit. When the receiving station receives the packet, the code error detection circuit 12 checks for the presence or absence of a code error in the received packet, and transfers only the packet in which no code error has been detected to the transmission status indication bit reference circuit 13. The packet input to the transmission status display bit reference circuit 13 refers to the transmission status indication bit assigned by the transmission status indication bit reference circuit 13 and also refers to the sequence number assigned by the sequence number reference circuit 14. Then, it is stored in the reception buffer 17.
The sequence number acquired by the sequence number reference circuit 14 is regarded as normal reception completion in the reception state management table 15, but acquired when the transmission state display bit reference circuit 13 detects a transmission state abnormality. The reception status management table 15 manages all reception statuses of packets older in time than the packet of the sequence number as normal reception. Further, the transmission status indication bit referred to by the transmission status indication bit reference circuit 13 is also transferred to the control information transmission circuit 16, and the control information transmission circuit 16 sequentially updates the information of the input transmission status indication bit, Whether the last input transmission status indication bit is abnormal or normal is stored. When the control information is returned from the receiving station to the transmitting station, the control information transmitting circuit 16 refers to the reception state management table 15, creates retransmission request information according to the reception state of the packet, and generates the last received packet. , And generates control information and returns it to the transmitting station. Packets stored in the reception buffer 17 can reverse the arrival order of the packets due to retransmission control.Therefore, the packet output control circuit 18 controls the output of the packets while sorting the order while grasping the reception state. Do.

The embodiments described above are all illustrative of the present invention and not restrictive, and the present invention can be embodied in other various modifications and alterations. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0051]

As described above in detail, according to the present invention, the packet delay time of the entire system is managed without managing the delay time on a packet basis, and the delay time of a packet waiting to be transmitted increases. Can temporarily suspend retransmission control or discard packets. As a result, it is possible to quickly remove excessively delayed packets from the transmission buffer. Furthermore, even with a method of managing the reception state of a packet on the receiving station side such as the GBN method, it becomes possible to apply control of retransmitting or abandoning a packet whose transmission has not been confirmed on the transmitting side, The delay time management on the transmission side can be performed without depending on the applied retransmission control method.

[Brief description of the drawings]

FIG. 1 is a diagram showing an operation conceptual diagram according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flow of processing for determining a delay state in one embodiment of the present invention described in claim 1;

FIG. 3 is a diagram showing a processing flow at the time of receiving control information on the transmitting station side in one embodiment of the present invention described in claim 1;

FIG. 4 is a diagram showing a transmission state determination processing flow in one embodiment of the present invention described in claim 2;

FIG. 5 is a diagram showing an operation conceptual diagram in one embodiment of the present invention described in claim 3;

FIG. 6 is a diagram showing a transmission state determination processing flow in an embodiment of the present invention described in claim 3;

FIG. 7 is a diagram showing a processing flow at the time of transmitting a packet in the embodiment of the present invention described in claim 4;

FIG. 8 is a diagram showing a processing flow at the time of receiving a packet in a receiving station according to an embodiment of the present invention described in claim 5;

FIG. 9 is a diagram showing a processing flow when control information is received by a transmitting station according to an embodiment of the present invention described in claim 5;

FIG. 10 is a functional block diagram of a transmitting station side error compensator according to an embodiment of the present invention described in claim 6;

FIG. 11 is a functional block diagram of a transmitting station side error compensator according to an embodiment of the present invention described in claim 7;

FIG. 12 is a functional block diagram of a receiving-station-side error compensator according to an embodiment of the present invention.

FIG. 13 is a diagram showing a processing flow at the time of receiving control information on the transmitting station side in the conventional system.

FIG. 14 is a diagram showing a processing flow at the time of receiving a packet on the receiving station side in the conventional system.

FIG. 15 is a diagram showing a processing flow at the time of transmitting control information of a receiving station in a conventional method.

FIG. 16 shows a functional block diagram of an error compensating device on the transmitting station side in the conventional system.

FIG. 17 shows a functional block diagram of an error compensating device on the receiving station side in the conventional system.

FIG. 18 is a diagram showing a processing flow for discarding a packet in which an excessive delay has occurred on the transmitting station side.

[Explanation of symbols]

 1 Sequence Number Assignment Circuit 2 Time Stamp Counter 3 Packet Input Time Management Circuit 4 Delay Status Judgment Circuit 5 Transmission Buffer 6 Transmission Packet Management Circuit 7 Control Information Receiving Circuit 8 Error Code Detection Circuit 9 Transmission Status Display Bit Addition Circuit 10 Transmission Status Management Circuit 11 Control information reception circuit 12 Code error detection circuit 13 Transmission status display bit reference circuit 14 Sequence number reference circuit 15 Reception state management table 16 Control information transmission circuit 17 Reception buffer 18 Packet output control circuit 101 Sequence number assignment circuit 102 Transmission buffer 103 Transmission Packet management circuit 104 Control information reception circuit 105 Error detection code assignment circuit 106 Code error detection circuit 107 Control information transmission circuit 108 Reception state management table 109 Sequence number reference circuit 110 Packet output control circuit 111 Receive buffer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoichi Matsumoto 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Masahiro Umehira 3-19, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation F term (reference) 5K014 AA03 BA01 DA02 EA05 FA03 5K030 GA12 HA10 HB15 HC15 JA05 JL01 KA13 LA02 LA04 LB11 LC11 MB02 MB13 5K033 AA05 AA07 CB04 CB06 CC01 DB14 DB16 EA06

Claims (7)

[Claims] In a system for continuously transmitting packets between a transmitting station and a receiving station via a wired or wireless communication, a sequence number is given to a transmitted packet,
The receiving station notifies the transmitting station of control information on the reception state of the packet on the control line, and the transmitting station temporarily stores the input packet in a transmission buffer and retransmits the packet or transmits a new packet according to the control information. Wherein the transmitting station includes a time stamp counter having a modulo M cycle for managing the current time, and the input time of the packet of sequence number i is used as the time stamp value TS (i). The time stamp value TS (k) of the oldest packet whose normal reception at the receiving station has not been confirmed or the packet scheduled to be transmitted from now on is acquired at a predetermined cycle or at an appropriate timing. The delay time δT, which is the difference between the stamp value TS (k) and the current time Tc, is defined as δT = Tc-TS (k) or δT = Tc-TS (k). +
The delay time is calculated based on δT that satisfies M> δT ≧ 0, and the delay time is determined by δT with respect to a predetermined threshold T1 where M>T1> 0.
If> T1, the state is managed as a transmission abnormal state, and a retransmission request for a packet described in the control information received from the receiving station is temporarily provided until the transmission state is restored to a normal state. An error compensating method characterized by ignoring the above, and sequentially transmitting a packet whose normal reception accumulated in the transmission buffer has not been confirmed and a new packet which has not been transmitted. 2. A system for continuously transmitting packets between a transmitting station and a receiving station via a wired or wireless network, wherein a transmitted packet has a sequence number,
The receiving station notifies the transmitting station of control information on the reception state of the packet on the control line, and the transmitting station temporarily stores the input packet in a transmission buffer and retransmits the packet or transmits a new packet according to the control information. Wherein the transmitting station includes a time stamp counter having a modulo M cycle for managing the current time, and the input time of the packet of sequence number i is used as the time stamp value TS (i). The time stamp value TS (k) of the oldest packet whose normal reception at the receiving station has not been confirmed or the packet scheduled to be transmitted from now on is acquired at a predetermined cycle or at an appropriate timing. The delay time δT, which is the difference between the stamp value TS (k) and the current time Tc, is defined as δT = Tc-TS (k) or δT = Tc-TS (k). +
The delay time is calculated based on δT that satisfies M> δT ≧ 0, and the delay time is δT with respect to a predetermined threshold T2 where M>T2> 0.
If> T2, the state is managed as a transmission abnormal state, and all or a part of the unacknowledged packets and the untransmitted new packets accumulated in the transmission buffer are discarded. Method. 3. The error compensation method according to claim 1, wherein said threshold values T1 and T2 are M>T2>T1>.
An error compensation method characterized by being 0. 4. The error compensation method according to claim 1, wherein the transmitting station adds a status indication bit indicating whether the transmission state is normal or abnormal to the packet to the packet. An error compensating method comprising: notifying the receiving station of the transmission state of the transmitting station by transmitting the data. 5. The error compensation method according to claim 4, wherein when the receiving station transmits control information to the transmitting station via a control line, the content of the transmission status indication bit added to the received packet. Is added to the control information to notify the transmitting station that the calculated delay time δT is δT> T1
Alternatively, when a state where δT> T2 is once detected, the transmission state is shifted to an abnormal state and managed, and when the control information is received, the transmission state is determined to return from the abnormal state to the normal state. Under the condition that the content of the transmission status indication bit added to the control information indicates abnormal and the delay status has recovered to δT ≦ T1 and δT ≦ T2, the transmission status changes from the abnormal status to the normal status. An error compensation method characterized by returning to a state. 6. In a system for continuously transmitting packets between a transmitting station and a receiving station via a wired or wireless communication, a sequence number is given to a transmitted packet,
The receiving station notifies the transmitting station of control information on the reception state of the packet on the control line, and the transmitting station temporarily stores the input packet in a transmission buffer and retransmits the packet or transmits a new packet according to the control information. 4. An error compensating apparatus using the error compensating method according to claim 1, wherein the transmitting station transmits control information, wherein the transmitting station receives control information transmitted by the receiving station. A circuit, a sequence number assigning circuit that assigns a sequence number to the input packet, a transmission buffer that stores the packet, a time stamp counter that manages the current time, and a time stamp value that indicates the time when the packet was input. A packet input time management circuit that manages packets together with packets, and a packet whose input time is the oldest at predetermined intervals or at appropriate timing. Calculates the delay time δt of the packet to be transmitted from the difference between the timestamp value t at the time of inputting the packet and the current timestamp value tc, and determines whether or not this value is equal to or greater than a predetermined threshold T. The delay time determination circuit and the packets in the transmission buffer to be initially transmitted or retransmitted are managed in the order of the oldest input time, and when the determination result from the delay time determination circuit is normal, the control information receiving circuit In response to the received control information, a new transmission packet or a retransmission packet is selected and output is instructed. On the other hand, if the determination result from the delay time determination circuit is abnormal, the control information reception circuit A transmission packet management circuit for temporarily ignoring the retransmission request in the received control information and / or discarding all or a part of the packets stored in the transmission buffer; An error compensating device comprising: an error detection code adding circuit that adds an error detection code to a packet to be transmitted. 7. In a system for continuously communicating packets between a transmitting station and a receiving station via a wired or wireless connection, a sequence number is assigned to a transmitted packet,
The receiving station notifies the transmitting station of control information on the reception state of the packet on the control line, and the transmitting station temporarily stores the input packet in a transmission buffer and retransmits the packet or transmits a new packet according to the control information. 5. An error compensating apparatus using the error compensation method according to claim 4, wherein the transmitting station comprises: a control information receiving circuit for receiving control information transmitted by the receiving station; A sequence number assigning circuit for assigning a sequence number, a transmission buffer for storing the packet, a time stamp counter for managing the current time, and a packet input time for managing the time when the packet was input as a time stamp value together with the packet The management circuit and a packet having the oldest input time or a packet to be transmitted from now on at a predetermined cycle or at an appropriate timing. The delay time δt of the packet is calculated from the difference between the time stamp value t at the time of inputting the packet and the current time stamp value tc, and a delay time determining circuit for determining whether or not this value is equal to or greater than a predetermined threshold T And a transmission state management circuit that determines whether the current transmission state is normal or abnormal based on the history of the determination result from the delay time determination circuit and the control information received from the receiving station, and a target for initial transmission or retransmission. The transmission state management circuit manages the packets in the transmission buffer in ascending order of input time, and when the transmission state is normal in the transmission state management circuit, a new transmission packet or retransmission according to the control information received by the control information reception circuit. A packet is selected and output is instructed. On the other hand, when the transmission state is abnormal in the transmission state management circuit, retransmission of the control information received by the control information reception circuit is required. A transmission packet management circuit for temporarily ignoring the request and / or discarding all or a part of the packet stored in the transmission buffer, and a transmission status for adding a transmission status indication bit indicating the current transmission status to the packet. A display bit addition circuit, and an error detection code addition circuit for adding an error detection code to a packet to be transmitted, wherein the receiving station determines whether the received packet has a code error,
A code error detection circuit that discards a received packet when a code error is detected, a transmission status indication bit reference circuit that determines whether the indication of a transmission status indication bit added to a normally received packet is normal or abnormal, and a normally received packet. And a sequence number reference circuit for acquiring the sequence number assigned to the packet, and managing the history of the packet transmission state by recording the sequence number acquired by the sequence number reference circuit. Performs management of the sequence number of the packet, and furthermore, when the acquired transmission status indication bit indicates an abnormality, the oldest sequence number management value that has not been normally received is changed to the value of the sequence number of the received packet. A reception state management table to be replaced and managed; and a reception state management table when transmitting the control information. Refer to the information that the packet that the loss due to the code error is confirmed or the packet that the receiving station expects to receive next through the sequence number, and the contents of the transmission status indication bit given to the received packet An error compensating apparatus comprising a control information transmitting circuit for generating and transmitting control information including: