CN105072637A - Transmission layer high-efficiency communication method facing time-varying wireless channel - Google Patents
Transmission layer high-efficiency communication method facing time-varying wireless channel Download PDFInfo
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- CN105072637A CN105072637A CN201510380918.8A CN201510380918A CN105072637A CN 105072637 A CN105072637 A CN 105072637A CN 201510380918 A CN201510380918 A CN 201510380918A CN 105072637 A CN105072637 A CN 105072637A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/04—Arrangements for maintaining operational condition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/0289—Congestion control
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Abstract
The invention discloses a transmission layer high-efficiency communication method facing a time-varying wireless channel, and the method combines with a network-facing scheme and an end-to-end scheme. Through the judgment of the state of a link, the method determines the type of a network fault, and then employs a corresponding control strategy. The method can distinguish the states of wireless links more accurately, and employs the corresponding processing strategy in a targeted manner according to the states of the links, thereby improving the accuracy of link fault elimination, and improving the transmission layer efficiency.
Description
Technical field
The present invention relates to wireless communication technology field, particularly relate to a kind of transport layer efficient communication method towards time-variant wireless channel.
Background technology
TCP is one and controls the self adaptive transmission agreement of its bearing load (by adjusting its window size) according to effective network bandwidth, and a kind of connection-oriented reliable transport-layer protocol, designs for cable network at first.Conventional TCP thinks that the reason of packet loss is because network congestion caused.
In the wireless network, the high bit-error of wireless link and node high-speed mobile etc. can cause packet loss, and Multi-path route and node-routing switching etc. can cause out of order.And TCP does not consider the out of order and packet loss caused by non-congested factor, with improvement conventional TCP is applied in wireless network if do not added, it also can be used as out of order for non-congested and packet loss is that network congestion causes, thus enter congestion control mechanism mistakenly, this will cause network throughput to reduce, hydraulic performance decline, has a strong impact on the usefulness of network.
In the wireless network, node location change causes network topology change, and routing relation is not fixed, and the error rate of wireless channel own is high in addition, and it is very general phenomenon that packet loss occurs, and can not determine because network congestion causes.
If according to wired TCP congestion control mechanism, above reason is all thought congested, seriously will reduce the throughput of network, waste link circuit resource.The key of wireless tcp optimization is accurately judging, on the basis of current transmission link state, to take suitable measure.
According to the source of state information, existing scheme can be classified as two large classes, a class is the improvement project of network-oriented (network-oriented), and a class is the improvement project of end-to-end (endtoend).
1), the scheme of network-oriented
The feature of the program is that state information derives from low layer or other nodes, and the transport layer of source node regulates transmission policy according to this state information, illustrates for TCP-F:
Source distinguishes route aging and network congestion by the RFN that intermediate node feeds back, and recovers normal transmission by RRN rerouting notice.
After the source of TCP receives the RFN routing failure notice of lower floor, snooze doze state will be entered.In this state, TCP stops the transmission of packet and freezes self some variablees (as cwnd, ssth) and timer RTO.
When after the notice packet receiving route RRN rerouting notice, TCP source could exit from this state and each variate-value before utilizing route to interrupt recovers the transmission of data.
The advantage of this solution is: cross layer design, and condition adjudgement is more accurate; Model is simple, is easy to modeling and simulating; Along with the rerouting time increases, promote successful.Deficiency is: cannot distinguish the state outside congested and route aging, such as channel error and route are unreachable.
2), scheme end to end
Feature: directly improve in the transport layer of transmit leg and recipient, keeps the end-to-end semanteme (note: confirm as semanteme) connected, and does not need amendment low layer and intermediate node.
As shown in Figure 1, be described for ADTCP:
ADTCP scheme, by detecting the multiple parameter of node, can distinguish that 4 state: CON residing for current connection are congested, the change of CHERR channel error, RTCHG route and DISC disconnection.
As shown in Figure 2, the adjacent packet delay difference of each transmission success statistics IDD, computing formula is: IDD=(rcvTime [i+1] – sndTime [i+1]) – (rcvTime [i] – sndTime [i]);
Every cycle T statistics STT short time throughput, computing formula is: bag number/time cycle that STT=confirms;
Every cycle T statistics PLR packet loss ratio, computing formula is: the bag number of bag number/transmission that PLR=1 – confirms;
Every cycle T statistics POR packet disorder ratio, computing formula is: the bag number of bag number/transmission that POR=is out of order;
It is congested that IDD adjacent packet delay difference and STT short time throughput two parameters can be used for judging whether network occurs, and upon occurrence of the congestion, IDD is adjacent, and packet delay difference must increase, and STT short time throughput must reduce.
When route changes, POR packet disorder ratio can increase.During Burst Channel mistake, PLR packet loss ratio can increase.
Present transmission link state can be judged according to the argument sequence of statistics when TCP source receives ACK or the RTO timer expiry of 3 repetitions.Sequence sorts from big to small.
The advantage of end-to-end solution is the information not relying on intermediate node or lower floor, only needs transport layer to judge; Very high for identifying of congestion situation.But also having it not enough, is namely easily be mistaken for congested for route aging or the inaccessible situation of route.
Summary of the invention
In view of this, the invention provides a kind of transport layer efficient communication method towards time-variant wireless channel, accurately can distinguish the state of wireless link, and take suitable control strategy, improve transport layer efficiency.
A kind of transport layer communication means towards time-variant wireless channel of the present invention, comprises the steps:
Step 0, initial condition in TCP transmission, i.e. slow turn-on state, arranges the length initial value of congestion window and the initial value of Slow start threshold;
Step 1, control transmitting terminal send packet within the scope of current congestion window, start corresponding timer while often sending a packet;
Step 2, in the process sending packet, judge the confirmation message ACK of corresponding data bag whether transmitting terminal received receiving terminal and feed back before each timer expiry:
1) if receive confirmation message ACK, then again judge whether have at least 3 all to indicate same lost data packets in confirmation message ACK:
1. if then judge the relation between current congestion window and current Slow start threshold:
If the Slow start threshold that the current congestion window < of A is current, judge currently to be in slow turn-on state, forward step 3 to;
If the Slow start threshold of the current congestion window of B >=current, judge currently to be in Congestion Avoidance state, forward step 4 to;
If not, then judge whether satisfied following condition 2.:
Current adjacent packet delay difference IDD to come before all adjacent packet delay difference IDD recorded by rank from big to small within 30%, and short time throughput STT come by rank from big to small all short time throughput STT recorded rear 30% within:
If met, then judge currently to be in queue burst error state, forward step 5 to; Wherein, current adjacent packet delay difference IDD refers to the transmission time difference of current packet and a upper packet; Short time, throughput STT referred to: the quantity of the packet be correctly received in the unit interval;
If do not met, judge currently to be in channel burst error condition, forward step 6 to;
2) if transmitting terminal does not receive the confirmation message ACK of receiving terminal feedback yet when timer expiry, judge that current being in transmits timeout treatment state, then forward step 7 to;
Step 3, expand congestion window to original 2 times, transmitting terminal continues to send packet within the scope of current congestion window, jumps to step 2;
Step 4, by the value of congestion window increase 512B, transmitting terminal continues within the scope of current congestion window transmission packet, jump to step 2;
Step 5, the half of current congestion window length that Slow start threshold is become, congestion window length is increased the message segment maximum length MSS of 3 times, resend the lost data packets indicated by confirmation message ACK, restart the timer that this lost data packets is corresponding simultaneously, transmitting terminal continues to send packet in order within the scope of current congestion window, jumps to step 2;
The length of step 6, maintenance Slow start threshold and congestion window is constant, resends the lost data packets indicated by confirmation message ACK, restarts the timer that this lost data packets is corresponding simultaneously, jump to step 2;
Step 7, maintenance Slow start threshold and congestion window are constant, and transmitting terminal suspends transmission data, and time out is greater than the routing update time, after the EOT end of timeout, and the routing state of destination node in table of query and routing:
1) if route can reach, then resend the lost data packets indicated by confirmation message ACK, restart the timer that this lost data packets is corresponding, and etc. confirmation message ACK to be feedback, then continue to judge:
If 1. confirmation message ACK can be received, then keep Slow start threshold and congestion window constant, jump to step 2;
If 2. can not receive confirmation message ACK, the value of Slow start threshold is become the half of current congestion window, congestion window value is become the message segment maximum length MSS of 1 times, enter slow turn-on state, jump to step 2;
2) if route is unreachable, then TCP transmission process is directly exited.
Preferably, the initial value of described congestion window is set to 512B.
Preferably, the initial value of described Slow start threshold is set to 64KB.
Preferably, the length of described message segment maximum length MSS is 512B.
The present invention has following beneficial effect:
Faying face of the present invention, to network plan and end-to-end scheme, can be distinguished the state of wireless link more accurately, take corresponding processing policy targetedly according to Link State, improves the accuracy getting rid of link failure thus, improves transport layer efficiency.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of existing end-to-end scheme.
Fig. 2 is that adjacent packet delay difference IDD calculates schematic diagram.
Fig. 3 is method flow diagram of the present invention.
Embodiment
To develop simultaneously embodiment below in conjunction with accompanying drawing, describe the present invention.
In the present invention, transmission link state is classified as following five kinds of states, as shown in table 1:
The definition of table 1, transmission link state
Wherein, packet loss refers to: TCP sends and adopts sliding window mechanism, if source receives 3 identical confirmation message ACK, or sliding window exhausts until timer expiry does not receive confirmation message ACK yet, then think and there occurs packet loss.
Based on above-mentioned five kinds of states, the invention provides condition adjudgement foundation, as shown in table 2:
The basis for estimation of table 2, transmission link state
Wherein, High represents that the rank of the parameter value of the last time in statistical parameter is higher than 70%.
Low represents that the rank of the parameter value of the last time in statistical parameter is lower than 30%.
In conjunction with above-mentioned condition adjudgement foundation, the transport layer efficient communication method that the present invention proposes, as shown in Figure 3, comprises the steps:
Step 0, initial condition in TCP transmission, i.e. slow turn-on state, arranges the initial value of congestion window, is generally 512B, arranges the initial value of Slow start threshold, is generally 64KB;
Step 1, control transmitting terminal send packet within the scope of current congestion window, start corresponding timer while often sending a packet;
Step 2, while transmission packet, judge whether transmitting terminal received the confirmation message ACK of packet corresponding to each timer that receiving terminal feeds back before each timer expiry:
1) if receive confirmation message ACK, then again judge whether have 3 packets all indicating same loss at least in confirmation message ACK:
1. if then judge the relation between current congestion window and current Slow start threshold:
If the Slow start threshold that the current congestion window < of A is current, illustrate and be currently in slow turn-on state, forward step 3 to;
If the Slow start threshold of the current congestion window of B >=current, illustrate and be currently in Congestion Avoidance state, forward step 4 to;
If not, then judge whether satisfied following condition 2.:
Current adjacent packet delay difference IDD to come before all adjacent packet delay difference IDD recorded by rank from big to small within 30%, and short time throughput STT come by rank from big to small all short time throughput STT recorded rear 30% within:
If met, then judge currently to be in queue burst error state, forward step 5 to; Wherein, current adjacent packet delay difference IDD refers to the transmission time difference of current packet and a upper packet; Short time, throughput STT referred to: the quantity of the packet be correctly received in the unit interval.
If do not met, illustrate and be currently in channel burst error condition, forward step 6 to;
2) if transmitting terminal did not receive the confirmation message ACK of receiving terminal feedback before timer expiry, illustrate that current being in transmits timeout treatment state, then forward step 7 to;
Step 3, slow turn-on state: congestion window is expanded to original 2 times, transmitting terminal continues to send packet within the scope of current congestion window, jumps to step 2.
Step 4, Congestion Avoidance state: the value of congestion window is increased 512B, continue within the scope of transmitting terminal congestion window in the updated to send packet, jump to step 2.
Step 5, queue burst error state: half Slow start threshold being become current congestion window value, congestion window is increased the message segment maximum length MSS of 3 times, resend the packet of the loss indicated by confirmation message ACK, start the timer that this lost data packets is corresponding simultaneously, within the scope of transmitting terminal congestion window in the updated, continuation sends packet in order, jumps to step 2.
Step 6, channel burst error condition: keep the value of Slow start threshold and congestion window constant, resend the lost data packets indicated by confirmation message ACK, start the timer that this lost data packets is corresponding simultaneously, jump to step 2;
Step 7, transmission timeout treatment state:
Keep Slow start threshold and congestion window constant, transmitting terminal suspend send data, time out is greater than the routing update time, after the EOT end of timeout, the routing state of destination node in table of query and routing:
1) if route can reach, then resend the lost data packets indicated by confirmation message ACK, start the timer that this lost data packets is corresponding, and etc. confirmation message ACK to be feedback, then continue to judge:
If 1. confirmation message ACK can be received, then illustrate that route there occurs change, and recovers, then keep Slow start threshold and congestion window constant, jump to step 2;
If 2. can not receive confirmation message, then illustrate and there occurs heavy congestion, the value of Slow start threshold is become the half of current congestion window, congestion window value is become the message segment maximum length MSS of 1 times, enter slow turn-on state, jump to step 2;
2) if route is unreachable, then TCP transmission process is directly exited.
In the present invention, parameter interpretation is as shown in table 3:
Table 3, parameter interpretation
In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (4)
1., towards a transport layer communication means for time-variant wireless channel, it is characterized in that, comprise the steps:
Step 0, initial condition in TCP transmission, i.e. slow turn-on state, arranges the length initial value of congestion window and the initial value of Slow start threshold;
Step 1, control transmitting terminal send packet within the scope of current congestion window, start corresponding timer while often sending a packet;
Step 2, in the process sending packet, judge the confirmation message ACK of corresponding data bag whether transmitting terminal received receiving terminal and feed back before each timer expiry:
1) if receive confirmation message ACK, then again judge whether have at least 3 all to indicate same lost data packets in confirmation message ACK:
1. if then judge the relation between current congestion window and current Slow start threshold:
If the Slow start threshold that the current congestion window < of A is current, judge currently to be in slow turn-on state, forward step 3 to;
If the Slow start threshold of the current congestion window of B >=current, judge currently to be in Congestion Avoidance state, forward step 4 to;
If not, then judge whether satisfied following condition 2.:
Current adjacent packet delay difference IDD to come before all adjacent packet delay difference IDD recorded by rank from big to small within 30%, and short time throughput STT come by rank from big to small all short time throughput STT recorded rear 30% within:
If met, then judge currently to be in queue burst error state, forward step 5 to; Wherein, current adjacent packet delay difference IDD refers to the transmission time difference of current packet and a upper packet; Short time, throughput STT referred to: the quantity of the packet be correctly received in the unit interval;
If do not met, judge currently to be in channel burst error condition, forward step 6 to;
2) if transmitting terminal does not receive the confirmation message ACK of receiving terminal feedback yet when timer expiry, judge that current being in transmits timeout treatment state, then forward step 7 to;
Step 3, expand congestion window to original 2 times, transmitting terminal continues to send packet within the scope of current congestion window, jumps to step 2;
Step 4, by the value of congestion window increase 512B, transmitting terminal continues within the scope of current congestion window transmission packet, jump to step 2;
Step 5, the half of current congestion window length that Slow start threshold is become, congestion window length is increased the message segment maximum length MSS of 3 times, resend the lost data packets indicated by confirmation message ACK, restart the timer that this lost data packets is corresponding simultaneously, transmitting terminal continues to send packet in order within the scope of current congestion window, jumps to step 2;
The length of step 6, maintenance Slow start threshold and congestion window is constant, resends the lost data packets indicated by confirmation message ACK, restarts the timer that this lost data packets is corresponding simultaneously, jump to step 2;
Step 7, maintenance Slow start threshold and congestion window are constant, and transmitting terminal suspends transmission data, and time out is greater than the routing update time, after the EOT end of timeout, and the routing state of destination node in table of query and routing:
1) if route can reach, then resend the lost data packets indicated by confirmation message ACK, restart the timer that this lost data packets is corresponding, and etc. confirmation message ACK to be feedback, then continue to judge:
If 1. confirmation message ACK can be received, then keep Slow start threshold and congestion window constant, jump to step 2;
If 2. can not receive confirmation message ACK, the value of Slow start threshold is become the half of current congestion window, congestion window value is become the message segment maximum length MSS of 1 times, enter slow turn-on state, jump to step 2;
2) if route is unreachable, then TCP transmission process is directly exited.
2. a kind of transport layer communication means towards time-variant wireless channel as claimed in claim 1, it is characterized in that, the initial value of described congestion window is set to 512B.
3. a kind of transport layer communication means towards time-variant wireless channel as claimed in claim 1, it is characterized in that, the initial value of described Slow start threshold is set to 64KB.
4. a kind of transport layer communication means towards time-variant wireless channel as claimed in claim 1, it is characterized in that, the length of described message segment maximum length MSS is 512B.
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| WO2017185353A1 (en) * | 2016-04-29 | 2017-11-02 | 华为技术有限公司 | Method, device and system for transmitting transmission control protocol (tcp) packet |
| CN109309928A (en) * | 2017-07-26 | 2019-02-05 | 华为技术有限公司 | D2D chain circuit detecting method, relevant apparatus and system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2017185353A1 (en) * | 2016-04-29 | 2017-11-02 | 华为技术有限公司 | Method, device and system for transmitting transmission control protocol (tcp) packet |
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| CN109309928B (en) * | 2017-07-26 | 2021-01-29 | 华为技术有限公司 | D2D link detection method, related device and system |
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Application publication date: 20151118 |