KR101043105B1 - Data unit receiver and transmitter control method - Google Patents

Abstract

A method of controlling a data unit receiver or data unit transmitter is described. The data unit receiver or transmitter includes a gap response procedure that responds to a gap in the sequence of data units received at the receiver. A readjustment detection procedure S12 is provided that detects a readjustment indication indicative of a potential readjustment of the data unit during transmission from the transmitter to the receiver, and a gap response procedure is adapted in response to the detection of the readjustment indication.

Data Unit Receivers, Data Unit Transmitters, Gap Detectors, Reconditioning Detectors, Adapters

Description

DATA UNIT RECEIVER AND SENDER CONTROL METHOD}

The present invention relates to a method of controlling a data unit receiver, a method of controlling a data unit transmitter, and a corresponding data unit receiver and transmitter.

The present invention relates generally to the field of communications via data unit transmission. In data unit communications, a stream of data symbols (e.g., bits or bytes) is divided by the transmitter into a number of units and transmitted to the receiver via an appropriate transmission network, which receiver receives the data symbol stream based on the received data unit. Reconstruct Normally this is done in connection with a hierarchy scheme such as the OSI scheme. That is, a transmitting peer of a given protocol is executed when receiving a data symbol stream from an upper layer, generating a data unit according to a given protocol attached by the transmitting peer, and transmitting the generated data unit to a lower layer. . On the receiving side, the receiving peer receives the data unit from the lower layer, reconstructs the data symbol scheme, and sends the reconstructed data symbol stream to the upper layer. The concept of splitting a data symbol stream into data units and the concept of layers are known in the art, where no further explanation is required.

Such subdivision of data consists of various names such as, for example, packets, segments, frames, protocol data units, service data units, and the like. In connection with the present specification and claims, the term “data unit” is generally used to refer to such subdivision of such data for communication.

In order for the data unit receiver to reconstruct the data symbol stream, the data units are transmitted in a predetermined sequence to provide each data unit with a sequence location identifier so that the receiver can arrange the received data units in the sequence determined by the transmitter. It is known to do. It is also known to provide gap detection and response procedures to data unit receivers to monitor sequence position identifiers within received data units to detect and respond to gaps between received data units for a given sequence. For example, a mechanism known from TCP checks whether a received data unit is exactly within the next sequence for the last data unit received in the sequence, otherwise the response procedure is a feedback message type to the data unit transmitter. Send a so-called duplicate acknowledgment (DUPACK) for the last data unit exactly received in the sequence.

It is also known to implement a corresponding gap response procedure at the data unit transmitter to respond to the gap reported by the data unit receiver. For example, in TCP, the data unit transmitter counts the number of DUPACKs and retransmits the data units associated with the gap (in the case where the TCP immediately follows the data unit identified in the DUPACK). As can be seen, the occurrence of a gap in the received data unit for the sequence is understood as an indication that the corresponding data unit is probably lost or significantly damaged in the process of transmitting from the transmitter to the receiver.

It is known that gaps in data units received for the sequence do not necessarily result in data unit loss, but can also reorder so-called data units. For example, since a previously transmitted data unit is excessively delayed in the network, it is readjusted that a later transmitted data unit precedes a previously transmitted data unit. As a result, the data unit receiver can receive the lost data unit causing the gap to be detected, without the data unit transmitter necessarily having to retransmit the lost data unit. This is precisely the reason why the data unit transmitter in TCP waits for the above-mentioned threshold of DUPACK before performing retransmission.

It is an object of the present invention to provide an improved method of gap detection and gap response in data unit based communication.

This object is solved by the main problem of the independent claim. Preferred embodiments are described in the dependent claims.

According to the present invention, it is proposed to provide a clear readjustment detection procedure for the data unit receiver and / or the data unit transmitter. The readjustment detection procedure is adapted to detect a readjustment indication indicating a potential readjustment of the data unit during transmission from the transmitter to the receiver. In addition, in response to the readjustment indication, it is proposed to adapt the gap detection and response procedure to the data unit receiver and / or to adapt the gap response procedure to the data unit transmitter.

The readjustment indication is some information that is appropriate to indicate that a readjustment will occur or has already occurred, so that the gap is not suitable for blaming the data unit loss. Thus, the gap detection and response procedure or the gap response procedure may determine that one or more gaps associated with the readjustment will be readjusted as indicated by the readjustment indication, such that the response of the portion of the data unit receiver and / or the data unit transmitter is readjusted. The indication is done in a different way than in the case where no indication is detected, in which case it will be assumed that the gap or multiple gaps will most likely be returned to loss.

In other words, by clearly monitoring the readjustment indication, by appropriately adapting the gap detection and response procedure to the receiver and / or the gap response procedure to the transmitter, the performance can be greatly improved compared to the prior art, where the data unit always transmits. Arriving in the same order as it was, it was assumed that the gap always turned to data unit loss. By monitoring and detecting the readjustment indication, the present invention allows the data unit receiver and / or the transmitter to be made aware of the readjustment so that the receiver and / or the sender can change their response by inferring that the gap is mainly due to the readjustment. Thus, by more appropriately responding to the most possible reason for the gap, the overall performance can be improved.

The readjustment indication may be set in any suitable or appropriate manner. For example, it may be based on a switch occurring in the path where the data unit is transmitted. In particular, an environment in which the data unit receiver and / or the transmitter is aware of a change in the path through which the data unit is transmitted, for example, has a number of paths or channels available to the transmitter to monitor the path by monitoring the transmission parameters (especially delays) of the path. In a properly selectable environment, the transmitter and / or receiver may evaluate whether a change in path will enable or necessarily rebalance.

The path change is observed by the transmitter or receiver, but is evenly observed by nodes in the network that transmit data units from the transmitter to the receiver (user plane nodes) and / or nodes that control the transmission (control plane nodes). It can be seen that. In the latter case, the network node will properly signal the path change to the receiver and / or the transmitter.

Optionally, the transmitter and / or receiver of the data unit communication may observe the history of the communication, in which case if the readjustment is made periodically due to some problem in the transmission network, for example, periodic repetition of the readjustment Can be observed. In this case, the transmitter and / or receiver may monitor the system time, and when the system time is within a range associated with the predicted repetitive readjustment, this may be determined as a readjustment indication.

The adaptation in response to the detection of the readjustment indication may be done in any suitable or preferred manner. For example, it can simply disable the gap response procedure. In other words, even if a gap is detected, nothing responds. Taking a TCP receiver as an example, this means that the DUPACK is not leaked. Disabling of the gap response on the transmitter side means, for example, that it is not counted in consideration of determining whether a received DUPACK has exceeded a DUPACK threshold.

As an alternative to the transmitter using the gap response procedure according to the DUPACK threshold, one can increase the DUPACK threshold as a response to the detection of the readjustment indication.

On the data unit receiver side, preferably, the adaptation of the gap detection and response procedure divides the received data unit into two or more groups according to the readjustment indication, so as to separate the gap detection and response procedure into two groups separately. Apply. "Individually" means that the receiver expects a gap in each group rather than between groups. Such a mechanism is preferable to completely disabling gap detection and response, but avoids response to gaps that may possibly be readjusted but do not result in data unit loss.

The above and other advantages and aspects of the present invention will be further understood from the study of the detailed embodiments provided below with reference to the accompanying drawings.

1 is a flow diagram of a method embodiment for controlling a data unit receiver.

2 is a flow diagram of a method embodiment for controlling a data unit transmitter.

3 schematically illustrates a transmitter and receiver capable of communicating over multiple paths to detect readjustment indications based on path switching.

4 is a flowchart of an example of detecting a readjustment indication based on a path switch.

5 shows a schematic embodiment of a data unit receiver.

6 shows a schematic embodiment of a data unit transmitter.

Although some of the following examples relate to certain layers, such as the link layer, network layer or transport layer, and certain protocols, such as TCP, the present invention is in no way limited to any particular communication layer or any particular protocol. The present invention can be applied in connection with any data unit based communication in which data units are transmitted in a defined sequence and gap detection and response procedures are used.

1 is a flowchart of a control method of a data unit receiver. Only this flowchart shows the components relating to the invention, and further conventional and known components for the control method of the data unit receiver are not shown so as not to obscure the subject matter of the invention. The method of FIG. 1 includes a gap detection and response procedure S11 that monitors the sequence location identifier of the received data unit and detects and responds to gaps between the received data units for the order sequence.

The gap detection procedure can be selected in any suitable or preferred manner. For example, it determines whether the currently received data unit is within the next sequence for the last received data unit before the currently received data unit, and the currently received data unit is the last received data unit before the currently received data unit. The gap can be detected if it is not in the next sequence for. This procedure may also be modified by determining whether the currently received data unit is in the next sequence for the data unit last received in the sequence before the currently received data unit, and detecting the gap if this is not the case. .

Another possibility of performing gap detection on the received data unit may be to wait for the reception of a predetermined number of data units to check whether the predetermined number of data units are contiguous for the predetermined sequence. For example, if the predetermined number is four and the data unit receiver receives four data units having the following order, that is, sequence position identifiers of 3, 4, 6 and 5, the data unit receiver is configured to receive these four received data units. It can be determined that there is no gap when arranged in this successive subsequence. On the other hand, the above-described method of checking whether a previously received data unit is within the next sequence with respect to the last data unit received is because a data unit having a sequence position identifier 6 follows a data unit having a sequence position identifier 4 Determine the gap.

The gap response procedure executed by the data unit receiver may also be selected in any suitable or preferred manner. Preferably, it sends an appropriate feedback message to the data unit transmitter to inform the data unit transmitter of the detected gap. For example, this can be done by sending a DUPACK, as described above.

The dotted lines above and below step S11 in FIG. 1 indicate that the control method generally includes additional steps and procedures, but is not relevant to the present invention and is not intended to be described any further.

1 also has a readjustment detection procedure S12. The readjustment detection procedure S12 is adapted to detect a readjustment indication indicating a potential readjustment of the data unit during transmission from the transmitter to the receiver. The readjustment indication may be selected in any suitable or preferred manner. For example, it may be information transmitted to the receiver by the network node or data unit transmitter involved in transmitting the data unit from the transmitter to the receiver. Likewise, the receiver itself can monitor certain communication parameters and derive a readjustment indication therefrom.

An example of this will be described with reference to FIG. 4. The flowchart of FIG. 4 illustrates method steps that may be executed by the readjustment detection procedure S12 of FIG. 1. The example of FIG. 4 relates to a state in which a receiver receives data units via two or more different paths, so that switching can occur between these paths. At this time, the readjustment indication may be caused by the switching of the path. In a first step S41, it is determined whether path switching has occurred. If YES, decision step S42 checks whether the readjustment is due to switching. This can be done, for example, by analyzing the delay associated with the two paths. In general, when switching from a path with a high delay (low speed path) to a path with a low delay (high speed path), data units transmitted over the high speed path may outperform previously transmitted data units on the low speed path. It can be seen that. That is, under certain conditions readjustment can be expected. Conditions for expected rebalancing are, for example, dslow > F * dfast, where dslow and dfast are the estimated transmission delays for the slow channel and the fast channel, respectively. f is a predetermined factor that sets the threshold above the threshold the receiver can expect to cause the switching from the slow path to the fast path to be reconditioned. As a result, in order to execute decision step S42 of FIG. 4, the data unit receiver may evaluate the delay through the available transmission paths. Such delay information may include, for example, a feedback message (eg, an acknowledgment message; ACK) that reports the transmission of a given data unit and the correct reception of the data unit, and that the data unit transmitter regularly reports the delay to the data unit receiver. Can be regularly measured by the data unit transmitter based on the time that elapses between receipts of the < RTI ID = 0.0 > Dedicated delay measurement techniques can also be used, such as echoing, which is treated as so-called ping.

If the result of step S42 indicates that a readjustment can be expected, step S43 determines the presence of a readjustment indication, and step S44 also determines that there is no readjustment indication.

The procedure of FIG. 4 is preferably implemented at the transmitter side when the transmitter can determine that the expected recalibration is given when tslow + dslow> tfast + dfast, where tslow and tfast are the slow channel and the fast, respectively. The moment of the last data unit transmission on the channel, dslow and dfast are the estimated transmission delays for the slow channel and the fast channel, respectively. The transmitter not only monitors both time tslow and tfast, but can also maintain a constant evaluation of the delays dslow and dfast. If the procedure of FIG. 4 is implemented at the transmitter side, step S43 may further include transmitting an appropriate signal or message to the receiver, whereby the receiver may determine receipt of a readjustment indication as detection. For example, such a readjustment indication may be set as a predetermined bit or bit string in the protocol header of the data unit. In addition, the readjustment indication may be signaled to the receiver in some other manner, eg, via a dedicated signal transmission connection.

3 schematically illustrates an example of a state in which a transmitter and a receiver may communicate over multiple paths that may have different delay characteristics. The transmitter 31 of the predetermined layer LX transmits a data unit to its peer 32. Layer LX may be, for example, link layer L2, network layer L3 or transport layer L4. The transmitter 31 receives the stream of data symbols from the higher layer LX + 1. The transmitter 31 includes a processor for controlling a data unit generating portion 310, eg a buffer, and a control portion 311, eg, a data unit generating portion 310. Moreover, it is assumed that there are a number of channels 33 for the lower layer LX-1, and the transmitter 31 includes a switching portion 312 that selects the channel. Layer LX-1 (and perhaps layer below LX-1) provides a connection 35 to receiver 32, where the data unit arrives through channel 34 corresponding to channel 33. As a result, the receiver 32 has a switching portion 322 which receives data units from the appropriate channel 34, which data units are adapted to assist in reconstructing the data symbol stream under the control of the control portion 321. 320). The reconstructed data symbol stream is passed to the upper layer LX + 1.

For example, if LX is link layer L2, then multiple channels 33, 34 may be connected to various WCDMA (wideband code division multiple access) connections, HSDPA (high speed downlink packet access) connections, Global System for Mobile communication (GSM), for example. It may be associated with a variety of different physical communication paths, such as connections, wireless local area network (WLAN) connections, or any other type of other wireless connection. The control method of the invention can then be implemented at a layer above the channel, for example at the so-called universal link layer (GLL).

Although it is a preferred embodiment to apply the concepts of the present invention to the general-purpose link layer, the present invention is in no way limited to this. The present invention applies equally to any reliable transmission protocol that can transmit over multiple paths, such as SCTP (Stream Control Transmission Protocol), or any suitable new version of Transmission Control Protocol (TCP) that provides multipath transmission. It is appropriate to.

In FIG. 4, step S42 includes, for example, the recording of a delay for the channel 34 where the control portion 321 can be measured, for example, by the transmitter 31 and regularly reported to the receiver. Can be implemented in the receiver 32, and whenever switching occurs in the switching element 322, the control portion 321 compares the delay on the old channel with the delay on the new channel, If the delay is less than the delay on the old channel by a predetermined threshold, the presence of the readjustment indication is determined.

Similarly, the method of FIG. 4 is implemented in the control element 311 of the transmitter 31, where step S42 is used to determine whether or not a readjustment indication is present or not as described above. It can be determined whether tfast + dfast.

In addition to the transmitter or receiver determining the presence of the readjustment indication, the network node involved in the processing of the data unit may provide the readjustment indication to the receiver and / or the transmitter. That is, switching between different available paths occurs in the network, and one or more network nodes can track the delay status on the available paths. Similarly to the above considerations, the network node may then determine the presence of the readjustment indication and notify the receiver and / or the transmitter. This can be done, for example, by setting a dedicated bit or bit stream in the data unit transmitted by the node or via a dedicated signal transmission connection. If the information is transmitted by setting a bit or bit stream in the data unit to which it is transmitted, the information can be transmitted from the receiver to the transmitter via mirroring. That is, the receiver receives a bit or bit stream and sets it in a feedback message (eg ACK) directed to the transmitter.

In FIG. 1, when step S13 determines that a readjustment indication exists, the procedure branches to step S14 where the gap detection and response procedure executed in step S11 is suitably adapted. This adaptation can be done in any suitable or preferred manner and will generally depend on the nature of the gap detection and response procedure S11. In general, this adaptation will, for example, make a response executed by S11 to a gap suitable for readjustment instead of the data unit loss that is the cause of the gap.

For example, this adaptation may simply disable the response to detection of the gap. This disabling can be maintained for a predetermined time, and if no longer a readjustment indication is detected to be present during this time, the gap detection and response procedure may be used to process the detected gap as a possible data unit loss. Normal "). As an example, if the response to the detection of the gap in S11 transmits the DUPACK, disabling means that during the particular time period the DUPACK is not transmitted if the gap is detected.

Preferably, the adaptation is done in a less coarse fashion by dividing the received data unit into two or more groups according to the readjustment indication, and using the gap detection and response procedures individually in this group.

"Individually" means expecting a gap in each group, not between groups.

The readjust indication may be associated with a given data unit. This association is given, for example, in that the readjustment indication is a particular marker in a given data unit and identifies the given data unit as the first data unit transmitted over the fast path (path with low delay), whereby the receiver Considers the data unit received before the given data unit to belong to the first group, and considers the given data unit and then the received data unit to belong to the second group. The gap detection procedure will then expect a gap in the first group or the second group rather than between the two groups. For example, data units with sequence position identifiers 2, 3, 4, and 5 are transmitted via the slow path, while data units with sequence position identifiers 6, 7, 8, ... are transmitted via the fast path, The data unit transmitter may display the data unit number 6 by the readjustment indication. Then, after the receiver receives the data unit with the sequence identifiers 2 and 3, when receiving the data unit with the sequence position identifier 6, it receives the first group terminating at the sequence position identifier 5 and the sequence position identifier 6 It is possible to distinguish the starting second group. In this way, for example, after receiving a data unit with sequence position identifiers 7, 8 and 9, if slow data units 4 and 5 arrive, a gap is detected when each subsequence in the two groups is arranged. It doesn't work. On the other hand, for example, after receiving the high speed data units 7, 8 and 9, the receiver receives the data unit 5 but not the data unit number 4, so that a gap in the first group can be detected.

In the above example, it can be seen that the association between the given data unit and the readjustment indication is made by the fact that the readjustment indication is included in the given data unit. Optionally, this association also serves temporarily, ie as a delimiter in which the arrival time or detection time of the readjustment indication defines the first and second groups. In other words, the first data received after this delimiting time is considered as the first data unit of the second group.

Another possibility of dividing a received data unit into two or more groups is to associate a readjustment indication with a range of sequence position identifiers, to consider a data unit having a sequence position identifier within this range as belonging to the first group, It can be given by dividing a received data unit into two or more groups by considering a data unit having a sequence position identifier outside this range as belonging to one or more second groups. For example, a transmitter may send a signal to a receiver that can arrange and receive a range of data units at some time (especially when a switch in a channel or path occurs). This range can be identified, for example, by the first sequence position identifier and the last sequence position identifier that are delimiters of this range. Naturally, ranges within these several sequences can be specified. The receiver then adapts the response procedure by finding a gap only within a range in the sequence that is not outside the border or such a range. For example, if the ranges {7-10} and {1-6} in the sequence are specified, the readjustment causes the data units to be in order {0, 7, 8, 9, 10, 1, 2, 3, 4, 5, 6}. Is received, the gap detection procedure does not detect the gap. (In contrast, the conventional approach interprets the reception of data unit 7 as a loss of data units 1-6.) On the other hand, if data unit 8 and / or 4 are lost, for example, the gap detection procedure indicates that a gap exists. Determine. The detection of this gap then triggers a response of the transmission of the feedback message, which also preferably reports only on the ranges in the sequence.

2 shows an example of a method of controlling a data unit transmitter in accordance with the principles of the invention. Similar to what has been described above in connection with FIG. 1, FIG. 2 shows only the components related to the invention, and other conventional control steps and procedures are not shown. This is indicated by the dotted line. The method of FIG. 2 includes a gap response procedure S21 that responds to a gap between data units received at the receiver for a cleaned up sequence. The gap response procedure may include, for example, analyzing a feedback message received from a receiver and, for example, after receiving a predetermined number of feedback messages identifying a particular gap in the sequence, and then selecting a data unit corresponding to the gap under a predetermined condition. Responding by retransmitting.

The method of FIG. 2 further includes a readjustment detection procedure S22 for detecting a readjustment indication indicating potential readjustment of the data unit during transmission from the transmitter to the receiver. The readjustment detection procedure S22 may be adapted in the manner described above with respect to step S12 of the receiver control method. That is, step S22 may be implemented by the method of FIG. 4 at the transmitter, where, in the case of a path switch, by the comparison between tslow + dslow and tfast + dfast of the described scheme, the presence or absence of a readjustment indication exists. It is determined whether or not. Preferably, step S22 is implemented in such a way that the data unit transmitter tracks the communication status and appropriately determines when readjustment can be expected. Moreover, the data unit transmitter may receive a readjustment indication from the data unit receiver or from a network node involved in processing the data unit. Then, as a result of the readjustment detection procedure S22, step S23 determines the presence of the readjustment indication, and the gap response procedure is adapted to step S24.

The adaptation executed in step S24 is, for example, disabling the response executed by the gap response procedure S21 into the gap between the received data units. For example, this response counts the DUPACK, meaning that disabling the response is not counted in consideration of possible retransmissions after the DUPACK has received a DUPACK of a predetermined threshold. Optionally, disabling may not cause retransmission. As with the implementation of the disabling feature at the data unit receiver, the implementation at the data unit transmitter is also preferably done in such a way that disabling is done for a predetermined time, provided that no further readjustment indication is received within this time. The gap response procedure returns to the "normal" state and again responds to the gap by presuming that the gap will be associated with data unit loss.

Optionally, the gap response procedure S21 counts the number of feedback messages identifying a gap in the sequence, comparing this counted number to a threshold, and, if exceeding the threshold, one or more data associated with the gap. In the case of including retransmitting the unit, the adaptation performed in step S24 preferably includes increasing the threshold in response to the detection of the readjustment indication. For example, in a data unit transmitter operating similar to TCP with a DUPACK threshold of 3, by detection of the readjustment indication, the DUPACK threshold is increased to a predetermined high value, such as 10, for example. In other words, if a timer is set and no further readjustment indication is detected within a predetermined time, the threshold is returned to its original value, which is preferably set as a presumption that the gap is related to data unit loss.

The concept of the present invention has been described so far with respect to a control method for a data unit receiver or a data unit transmitter. As such, the invention may also be practiced as a computer program product comprising a computer program that, when executed on a data unit transmitter or data unit receiver, performs all the steps and procedures of the method described above.

The invention may also be practiced in the form of a data unit receiver or a data unit transmitter. 5 shows a data unit receiver 50 that connects to a network (not shown) via a connection 53 and receives a data unit 54 from a transmitter via the network. The transmitter is configured to transmit the data units 54 in a given sequence, where each data unit 54 includes a sequence location identifier to allow the receiver 50 to position the data units in the correct order of the sequence. The receiver 50 includes a data unit processing portion 51 (similar to portion 320 of FIG. 3) and a control portion 52 (similar to portion 321 of FIG. 3). The control portion 52 includes, in particular, a gap detector 520 that monitors the sequence position identifier of the received data unit to detect and respond to gaps between the received data units for a given sequence. Moreover, the control portion 52 includes a readjustment detector 522 that detects a readjustment indication that indicates a potential readjustment of the data unit during transmission from the transmitter to the receiver and further includes a gap detector 520 in response to the detection of the readjustment indication. Adapter 521 that adapts to < RTI ID = 0.0 > After reconstructing the original data stream from the received data unit 54, this data stream can be transmitted via the connection 55 to the upper layer.

It will be appreciated that the gap detector 520, readjustment detector 522, and adapter 521, as well as the control portion 52, can be provided in hardware, software, or any suitable combination of hardware and software. Preferably, control portion 52 is a programmable processor and gap detector 520, readjustment detector 522, and adapter 521 are code portions of a computer program running on this processor.

Similarly, FIG. 6 shows a schematic example of a data unit transmitter 60 that connects to a network (not shown) via a connection 63 and transmits the data unit 65 to a receiver via the network. . The transmitter 60 is configured to transmit the data units 65 in a predetermined sequence, where each data unit 65 includes a sequence location identifier. The receiver sends a feedback message 66 back to the transmitter 60, which provides information on the gap for a given sequence among the data units received at the receiver. Transmitter 60 includes a data unit generation portion 61 (similar to portion 310 of FIG. 3) and a control portion 62 (similar to control portion 311 of FIG. 3). Control portion 62 includes a gap responder 620 that responds to a gap between data units received at the receiver for a given sequence, a readjustment detector that detects a readjustment indication indicating a potential readjustment of the data unit during transmission from the transmitter to the receiver; 622 and an adapter 621 that adapts to the gap responder 620 in response to the detection of the readjustment indication.

It will be appreciated that the gap responder 620, readjustment detector 622 and adapter 521, as well as the control portion 62, may be provided in hardware, software, or any suitable combination of hardware and software. Preferably, control portion 62 is a programmable processor, and gap responder 620, readjustment detector 622 and adapter 621 are code portions of a computer program executing on this processor.

Although the present invention has been described in connection with specific embodiments, these embodiments are merely for thorough understanding and are not intended to be limiting. Rather, the scope of the invention is determined by the appended claims. Reference signs in the claims are intended to make the claims easier to read and are not intended to have any limiting effect.

Claims (16)

A method of controlling a data unit receiver 50 configured to receive a data unit 54 from a transmitter over a network, wherein the transmitter is configured to transmit the data unit 54 in a predetermined sequence, each data unit 54. ) Contains the sequence location identifier, In the data unit receiver 50, a gap detection and response procedure (S11) for monitoring the sequence position identifier in the received data unit, detecting a gap between data units received for the determined sequence, and responding to the gap. In the control method of a data unit receiver comprising: In the data unit receiver 50, a readjustment detection procedure (S12) for detecting a readjustment indication indicating whether or not a readjustment of a data unit has occurred during transmission from the transmitter to the receiver; And a step (S14) of adapting the gap detection and response procedure in response to the detection of the readjustment indication. The method of claim 1, The gap detection and response procedure S11 determines whether a currently received data unit is within a next sequence of the last received data unit before the currently received data unit, and the currently received data unit is currently received. Detecting a gap if not within the next sequence of data units last received before the data unit. The method according to claim 1 or 2, The receiver (50) is configured to receive the data unit (54) via two or more paths, and the readjustment indication is made by switching between the two or more paths (S41). The method according to claim 1 or 2, And the readjustment indication is signaled to the receiver (50) by one or both of the transmitter and the nodes of the network. The method according to claim 1 or 2, The procedure of adapting the gap detection and response procedure disables the response to the gap between the received data units for the given sequence. The method according to claim 1 or 2, The procedure of adapting the gap detection and response procedure includes dividing the received data unit into two or more groups according to the readjustment indication, and applying the gap detection and response procedure individually to the group. The control method of the data unit receiver characterized by the above-mentioned. The method of claim 6, The readjustment indication is associated with a given data unit, and wherein the step of dividing the received data unit into two or more groups considers the data unit received before the given data unit to belong to a first group and the given data And a unit of the data unit received after the given data unit as belonging to a second group. The method of claim 7, wherein And the readjustment indication is a predetermined marker in the given data unit. The method of claim 6, The readjustment indication is related to a range of sequence position identifiers, and wherein the step of dividing the received data unit into two or more groups considers a data unit having a sequence position identifier within the range to belong to a first group, And considering a data unit having a sequence location identifier outside the range as belonging to at least one second group. The method of claim 9, And the range of the sequence position identifier is signaled by the transmitter to the receiver. A method of controlling a data unit transmitter (60) configured to transmit a data unit (65) to a receiver via a network, wherein the transmitter (60) is configured to transmit the data unit in a predetermined sequence, each data unit being a sequence A location identifier, the receiver sends a feedback message 66 to the transmitter 60, the feedback message 66 providing information on the gap for the determined sequence between data units received at the receiver. to do, In the data unit transmitter (60), in the control method of the data unit transmitter comprising a gap response procedure (S21) for responding to the gap between the received data unit for the predetermined sequence, In the data unit transmitter 60, a readjustment detection procedure (S22) for detecting a readjustment indication indicating whether or not a readjustment of a data unit has occurred during transmission from the transmitter to the receiver; And a step (S24) of adapting the gap response procedure in response to the detection of the readjustment indication. The method of claim 11, The procedure of adapting the gap response procedure disables the response to the gap between the received data units for the determined sequence. 13. The method according to claim 11 or 12, The gap response procedure includes counting the number of feedback messages identifying a gap in the sequence, comparing the counted number with a threshold, and retransmitting one or more data units associated with the gap if the threshold is exceeded. Include, The procedure of adapting the gap response procedure includes increasing the threshold in response to the detection of the readjustment indication. 13. The method according to claim 11 or 12, And the readjustment indication is signaled to the transmitter by one or both of the receiver and the nodes of the network. A data unit receiver 50 connectable to receive a data unit 54 from a transmitter via a network, the transmitter being configured to transmit the data unit 54 in a predetermined sequence, each data unit 54 being a sequence position Contains an identifier, A data unit receiver comprising a gap detector 520 for monitoring the sequence location identifier in the received data unit, detecting a gap between the received data units for the given sequence and responding to the gap; A readjustment detector 522 for detecting a readjustment indication indicating whether or not a readjustment of a data unit has occurred during transmission from the transmitter to the receiver; And an adapter (521) adapted to the gap detector in response to the detection of the readjustment indication. A data unit transmitter 60 connectable to transmit a data unit 65 to a receiver via a network, wherein the transmitter 60 is configured to transmit the data unit 65 in a predetermined sequence, each data unit 65. Includes a sequence location identifier, the receiver sends a feedback message 66 to the transmitter 60, which feedback message 66 is on a gap for the determined sequence between the data units received at the receiver. Provide information, A data unit transmitter comprising a gap responder 620 responsive to a gap between the received data units for the given sequence, A readjustment detector 622 for detecting a readjustment indication indicating whether or not a readjustment of a data unit has occurred during transmission from the transmitter to the receiver; And an adapter (621) adapted to the gap responder in response to the detection of the readjustment indication.

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