CN102111820B - Method for realizing scheduling control of network encoding perceived by transmission control protocol in wireless network - Google Patents
Method for realizing scheduling control of network encoding perceived by transmission control protocol in wireless network Download PDFInfo
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Abstract
The invention relates to a method for realizing the scheduling control of network encoding perceived by a transmission control protocol (TCP) in a wireless network, which comprises the following steps of: establishing a wireless network encoding model, a wireless channel model and a TCP model; assessing the channel quality of a wireless network system and the dynamic performance of the TCP; allocating a channel rate encoding mode in real time; encoding a group of TCP data packets selected from an intermediate node; and responding to a sender of the group of TCP data packets and forwarding the encoded data packets. By adopting the method for realizing the scheduling control of the network encoding perceived by the TCP in the wireless network, the change of channels can be known correctly, and an acknowledgement message is further sent to the sender of the data packets quickly and effectively, so network congestion is reduced, the transmission performance is improved, band width can be utilized effectively to allow the network to have higher throughput, the utilization rate of the band width is improved, wireless resources can be better utilized, the working performance is stable and reliable, and the application range is wide.
Description
Technical field
The present invention relates to wireless communication field, particularly TCP transmission performance optimization technical field in wireless communication procedure, specifically refers to that a kind of wireless network realizes the method that transmission control protocol sensing network coded scheduling is controlled.
Background technology
The mode that traditional communication network transmits data is that node forwards, and except sending node and the node receiving node of data are only responsible for route, and data content is not done to any processing, and intermediate node is being played the part of the role of transponder.For a long time, people generally believe on intermediate node the data of transmission are processed and do not had any income, yet the network code theory that the people such as RAhlswede proposed in 2000 has thoroughly been overthrown this traditional view.
Network code (NC) has brought huge benefit, especially in wireless communication field.Network code can be considered to the extension of traditional Routing Protocol aspect intermediate point and the packets of information of hopping.The basic conception of network code is that many packets of information, by the clever packets of information that is encoded into a coding, and then are broadcasted away on an intermediate node.Not only the transmission in network being beneficial to of this processing, and can enrich the information of transmission.In addition, thus use the effective rate of utilization that can improve bandwidth after network code to improve the throughput of network.In wireless communication field, the limited people of making of bandwidth resources have given the concern of height to network code.
But, in the prior art, in the research of network code, also do not consider the dynamic of TCP and the research of wireless random schedule and occur.
Meanwhile, in legacy network coding, when a node obtains the chance of transmission, first it find any utilizable code machine meeting.It only uses the reception obtaining from neighbors to report.In other words, such a node does not have the information of transmitting channel aspect.And it does not change the information of TCP parameter variation aspect for adaptive channel.Therefore, this just make querying node to a lot of code machines can be all false, this just means because channel error expection recipient can not receive the bag of maybe can not decoding.Result is that TCP retransmits and the overtime performance that makes reduces.
Moreover, in conventional method, also has a slightly improved network code scheme.In this scheme, when a node obtains the chance of transmission, it is by employing a more senior algorithm to search code machine meeting.In this more senior method, consider the reception report and the channel condition that from adjacent cell, receive and decide which packet encoder to put together.This method has guaranteed that local bag is included in encoded packets, the link-quality that coding is surrounded by.It is high a lot of that this just means that recipient receives the success rate of bag.Equally, it is by employing rate adapted to utilize transient link condition.Yet it is introduced random data speed when link-quality is poor and reduces by half until link-quality improves.This has just caused the overtime event of frequent TCP vacation, thereby has reduced TCP performance.And, if when TCP transmission rate is very high, when link-quality channel speed low and that distribute is low, can occur congested, thereby reduce TCP performance.
Summary of the invention
The object of the invention is to have overcome above-mentioned shortcoming of the prior art, provide a kind of can in wireless communication procedure, make TCP transmission performance optimum, improve network throughput, improve the utilance of bandwidth, better utilize Radio Resource, stable and reliable working performance, the scope of application comparatively widely wireless network realize the method that transmission control protocol sensing network coded scheduling is controlled.
In order to realize above-mentioned object, the method that wireless network of the present invention is realized the control of transmission control protocol sensing network coded scheduling is as follows:
In this wireless network, realize the method that transmission control protocol sensing network coded scheduling is controlled, its main feature is that described method comprises the following steps:
(1) in Radio Network System, set up Wireless Network Coding model, wireless channel model and transmission control protocol model;
(2) according to wireless channel model and transmission control protocol model, respectively the channel quality of Radio Network System and transmission control protocol dynamic property are carried out to evaluation process;
(3) according to the result of evaluation process, the channel speed coded system in Radio Network System is configured in real time;
(4) intermediate node in Radio Network System is determined the processing of encoding of one group of tcp data bag according to Wireless Network Coding Model Selection;
(5) described intermediate node responds the sender of this group tcp data bag, and the packet after coding is processed carries out forward process.
In this wireless network, realize and set up Wireless Network Coding model in the method that transmission control protocol sensing network coded scheduling controls, comprise the following steps:
(11) in the intermediate node of Radio Network System, set up local data packet buffer, in described local data packet buffer, store this intermediate node from wireless network monitoring reception to packet and by this intermediate node oneself, produced and the packet at free interval;
(12) in the intermediate node of Radio Network System, set up lower-priority data packet buffer, in described lower-priority data packet buffer, store this intermediate node from wireless network monitoring reception to not need to send to the packet of other node.
The local data packet buffer realizing in this wireless network in the method that transmission control protocol sensing network coded scheduling controls is also carried out following processing operation:
(111) by described intermediate node institute monitoring reception to the processing of decoding of the packet crossed of coding;
(112) situation of the packet arriving according to this intermediate node institute monitoring reception creates and receives report, and shares to the node adjacent with this intermediate node.
In this wireless network, realize the wireless channel model of setting up in the method that transmission control protocol sensing network coded scheduling controls, be specially:
According to following Formula wireless channel model P
e:
Wherein,
K
1and k
2be the factor of coding criterion, N
retransfor sending times, N
frfor the frame number of packet, L
frthe frame length of packet, BER is error rate.
In this wireless network, realize, in the method that transmission control protocol sensing network coded scheduling controls, the channel quality of Radio Network System and transmission control protocol dynamic property carried out to evaluation process, comprise the following steps:
(21) according to wireless channel model, obtain signal and interference and the noise ratio SINR of the channel of Radio Network System;
(22) at the sending node of Radio Network System, judge the relation between TCP congestion window state parameter η, α, β and the current state n of TCP congestion window responding, wherein:
1≤η < α < β≤N, N is the size of TCP send window.
In this wireless network, realize the channel speed coded system in Radio Network System is configured in real time according to the result of evaluation process in the method that transmission control protocol sensing network coded scheduling controls, comprise the following steps:
(31) if β < is n≤N, TCP transmission rate is very high, and Radio Network System is configured to high channel rate coding mode;
(32), if α < is n≤β, Radio Network System is configured to minimum channel rate coding mode;
(33), if η < is n≤α, Radio Network System is configured to the coded system that channel speed is not less than QPSK;
(34) if 1≤n≤η is configured to Radio Network System the coded system that channel speed is not less than BPSK.
The high channel rate coding mode realizing in this wireless network in the method that transmission control protocol sensing network coded scheduling controls is QAM64 coded system.
The minimum channel rate coding mode realizing in this wireless network in the method that transmission control protocol sensing network coded scheduling controls is QAM16 coded system.
In this wireless network, realize and according to Wireless Network Coding Model Selection, determine the processing of encoding of one group of tcp data bag in the method that transmission control protocol sensing network coded scheduling controls, comprise the following steps:
(41) described intermediate node is based on Wireless Network Coding model, and the reception report and the default screening rule that according to adjacent node, send screen received tcp data bag;
(42) described intermediate node determines according to the channel speed coded system of the instant channel condition of the TCP transmission rate of each tcp data bag, all relevant wireless links and configuration in real time one group of tcp data bag will encoding and process;
(43) to the processing of encoding of this group tcp data bag, and obtain corresponding coded data packet.
The default screening rule of realizing in this wireless network in the method that transmission control protocol sensing network coded scheduling controls comprises:
(411) bag being produced by described intermediate node oneself can not be encoded as one group of packet;
(412) having the packet that the identical next one jumps a little can not encode as one group of packet;
(413) if the next one of packet transmits the channel quality of link lower than the requirement of the coded system of lowest channel speed, by this data packet discarding.
In this wireless network, realize in the method that transmission control protocol sensing network coded scheduling controls to the processing of encoding of this group tcp data bag, be specially:
With XOR bit arithmetic symbol, this group tcp data bag is encoded.
In this wireless network, realize code rate that the carrying out coding in the method that transmission control protocol sensing network coded scheduling controls the processes speed for requiring this locality that speed is minimum to wrap in this group packet.
In this wireless network, realize in forwarding information packet header of the coded data packet in the method that transmission control protocol sensing network coded scheduling controls and there is local data package informatin, the recipient information of each local packets, the reception report information of this intermediate node, reporting quantities field and the group/cording quantity field after coding.
In this wireless network, realize and set up transmission control protocol model in the method that transmission control protocol sensing network coded scheduling controls, be specially:
Based on TCP Reno algorithm, set up transmission control protocol model.
Adopted the wireless network of this invention to realize the method that transmission control protocol sensing network coded scheduling is controlled, due to wherein based on existing feasibility study network code performance limited, utilized the chance dispatching algorithm in mobile radio network, on the intermediate node of wireless network, consider which decides aspect the dynamic of TCP and link condition two be coatedly encoded into an encoded packets and use what data rate coding, thereby can in unpredictable link condition, know accurately that thereby any channel-changing can send acknowledge message ACK fast and effectively to the sender of TCP bag, reduced network congestion, especially the present invention has considered that congestion window size (a TCP parameter) and the condition of wireless channel improve TCP transmission performance, thereby can make network have higher throughput thereby can make bandwidth be used more effectively, improved the utilance of bandwidth, can better utilize Radio Resource, stable and reliable working performance, the scope of application is comparatively extensive.
Accompanying drawing explanation
Fig. 1 is the forwarding information packet header frame structure schematic diagram that wireless network of the present invention is realized the coded data packet in the method that transmission control protocol sensing network coded scheduling controls.
Embodiment
In order more clearly to understand technology contents of the present invention, especially exemplified by following examples, describe in detail.
Refer to shown in Fig. 1, realize the method that transmission control protocol sensing network coded scheduling is controlled in this wireless network, its main feature is that described method comprises the following steps:
(1) in Radio Network System, set up Wireless Network Coding model, wireless channel model and transmission control protocol model; Set up Wireless Network Coding model, comprise the following steps:
(a) in the intermediate node of Radio Network System, set up local data packet buffer, in described local data packet buffer, store this intermediate node from wireless network monitoring reception to packet and by this intermediate node oneself, produced and the packet at free interval; This local data packet buffer is also carried out following processing operation:
(i) by described intermediate node institute monitoring reception to the processing of decoding of the packet crossed of coding;
(ii) situation of the packet arriving according to this intermediate node institute monitoring reception creates and receives report, and shares to the node adjacent with this intermediate node;
(b) in the intermediate node of Radio Network System, set up lower-priority data packet buffer, in described lower-priority data packet buffer, store this intermediate node from wireless network monitoring reception to not need to send to the packet of other node;
Set up wireless channel model, be specially:
According to following Formula wireless channel model P
e:
Wherein,
K
1and k
2be the factor of coding criterion,
N
retransfor sending times, N
frfor the frame number of packet, L
frthe frame length of packet, BER is error rate;
Set up transmission control protocol model, be specially:
Based on TCP Reno algorithm, set up transmission control protocol model;
(2) according to wireless channel model and transmission control protocol model, respectively the channel quality of Radio Network System and transmission control protocol dynamic property are carried out to evaluation process, comprise the following steps:
(a) according to wireless channel model, obtain signal and interference and the noise ratio SINR of the channel of Radio Network System;
(b) at the sending node of Radio Network System, judge the relation between TCP congestion window state parameter η, α, β and the current state n of TCP congestion window responding, wherein:
1≤η < α < β≤N, N is the size of TCP send window;
(3) according to the result of evaluation process, the channel speed coded system in Radio Network System is configured in real time, comprises the following steps:
(a) if β < is n≤N, TCP transmission rate is very high, and Radio Network System is configured to high channel rate coding mode; This high channel rate coding mode can be QAM64 coded system, can be also other suitable coded system;
(b), if α < is n≤β, Radio Network System is configured to minimum channel rate coding mode; This minimum channel rate coding mode can be QAM16 coded system, can be also other suitable coded system;
(c), if η < is n≤α, Radio Network System is configured to the coded system that channel speed is not less than QPSK;
(d) if 1≤n≤η is configured to Radio Network System the coded system that channel speed is not less than BPSK;
(4) intermediate node in Radio Network System is determined the processing of encoding of one group of tcp data bag according to Wireless Network Coding Model Selection, comprises the following steps:
(a) described intermediate node is based on Wireless Network Coding model, and the reception report and the default screening rule that according to adjacent node, send screen received tcp data bag; This default screening rule comprises:
(i) bag being produced by described intermediate node oneself can not be encoded as one group of packet;
(ii) having the packet that the identical next one jumps a little can not encode as one group of packet;
(iii) if the next one of packet transmits the channel quality of link lower than the requirement of the coded system of lowest channel speed, by this data packet discarding;
(b) described intermediate node determines according to the channel speed coded system of the instant channel condition of the TCP transmission rate of each tcp data bag, all relevant wireless links and configuration in real time one group of tcp data bag will encoding and process;
(c) to the processing of encoding of this group tcp data bag, and obtain corresponding coded data packet, be specially: with XOR bit arithmetic symbol, this group tcp data bag is encoded;
The code rate of this processing of encoding is for requiring the speed of this locality bag that speed is minimum in this group packet; In the forwarding information packet header of coded data packet, there is local data package informatin, the recipient information of each local packets, the reception report information of this intermediate node, reporting quantities field and group/cording quantity field after coding;
(5) described intermediate node responds the sender of this group tcp data bag, and the packet after coding is processed carries out forward process.
In the middle of reality is used, the correlation model in method of the present invention is as follows:
In algorithm of the present invention, the model that need to use, comprises network code model, wireless channel model, and TCP model:
(1) network code model:
In order to make coding there is randomness, the packets of information in the random monitoring network of intermediate node.The packets of information that crawl listens to and it is deposited in a local buffer (local data packet buffer) that is named as packetPool.In packetPool, storage, except the packets of information of monitoring, is also stored by node oneself and is produced the packets of information that has the special time interval.Packets of information in packetPool is used for doing two things: the one, and, decoding passes the packets of information of crossing into the coding of node; The 2nd,, create reception report and share to neighbors.No matter when node has obtained the chance of a transmission, and it all will receive report add in the bag sending the information with other nodes sharing.When other neighbors listens to such bag, they extract and receive report and upgrade local information.Each node also has another one in lowPriorityBuffer buffer (lower-priority data packet buffer).Those that in the buffer of lowPriorityBuffer, storage listens to are not the packets of information that will issue certain node.This has just guaranteed that traditional interface queue can not flooded by the packets of information of coming from network.This has also reduced those in addition the potential extra process load that may reduce the node life-span.In addition, this has been avoided unnecessary forwarding bag to impact network.Only have the bag of node oneself generation and the bag forwarding by node can pass through IFQ (fair queuing algorithm).Bag in lowPriorityBuffer only have and the packet encoder by IFQ after just can be transmitted, otherwise be dropped after a specific time interval.
Suppose that node all shared their reception report.When a node has data to transmit, first scheduler program checks that the reception report coming from neighbors decides which bag coding of putting together.Note, those bags that produced by node oneself will be weaved into one group of bag never.Reason is not have neighbors to monitor such bag.In addition, there is bag that the identical next one jumps a little coding of also not putting together.If so done, recipient's its this locality bag of can not decoding so.ρ ∈ ψ={ P
1, P
2..., P
lit is the combination of the one group of bag that will encode.Scheduler program is used the channel information of the decision radio link quality of collecting to determine which coated top that adds.If bag ρ, its link-quality is very poor, even if poor lowest modulation strategy all can not be used, such bag will remove from combination ψ.According to the TCP transmission rate of each bag, considered the instant channel condition of all relevant wireless links, scheduler program distributes best data rate to the encoded packets producing from combination ψ.When final decision after the one group of bag that will encode, with XOR bit arithmetic, accord with encoding.In the forwarding information packet header of encoded packets (referring to shown in Fig. 1), we annotate the information of this locality bag in the bag after coding and their recipient, so recipient just can know the recipient whether they expect.Equally, it can help which bag of receiver decision will be used to decode.Reception also will be added before being reported in bag transmission.In Fig. 1, receive reporting quantities (Report num) and group/cording quantity (Encoded num) territory and all distributed a byte.Here supposition:
● a node is due to internal memory, and the reasons such as limitation of power and calculating can not keep (or processing) to surpass 256 monitoring bags in packetPool.
● a node can not be encoded and be surpassed 256 local bags.
Equally, other nodes are also such abilities, and this just means that forwarding information packet header can produce.Therefore, wrap oversizely, this is to reduce network performance.Should be noted that and use local search network code algorithm to replace detailed search algorithm.These are all that hypothesis node resource limited and detailed inquiry may be introduced unwarranted unnecessary delay and causes reducing network throughput.
Strategy of the present invention is to use different unicast mode methods.Suppose collective's information content that bag P carries each bag, P={P
1, P
2..., P
l.Bag P can only send in the numerous recipients of these encoded packets to.The benefit of this method has been minimized confirmation bag in network, and if not this method, each recipient will return to one and confirms will reduce so effective utilization of bandwidth by bag so.Equally, because encoded packets only comprises this locality bag that wireless link is good, bag transmits successful possibility and the successful possibility of decoding will be very high.
If K is the number of local bag in encoded packets, for can successfully decoded, the recipient of expection must have wherein K-1 local bag.In the process of decoding, with the bag in local packetPool, encoded packets is carried out to XOR bit arithmetic.If some node that is not expection recipient listens to such bag and also have K-1 to be used for the bag of decoding bag P, it can extract this locality bag that it does not have and store in packetPool so.
(2) channel model:
In the scope of a square kilometre, the present invention uses TwoRayGround model as propagation model.The error rate of setting bag in the present invention is that 0.01.MAC layer number of retransmissions is 6. for object simple and simulation, and the size of TCP bag is set as 100 bytes.Through-put power is 100 watts.Suppose that channel estimating is desirable.Suppose that sender receives channel information there from recipient.Use following formula (1), (2), (3), the present invention determines the SINRs (Signal to Interference plus Noise Ratio signal and interference and noise ratio) (as shown in the following Table 1) that will use in different modulation strategies as required:
K wherein
1and k
2the a series of contents in coding criterion.Especially, N
retransthe number of times of retransmitting, N
frframe number, L
frbe frame length, and BER is error rate.
Table 1 modulation strategy and Signal to Interference plus Noise Ratio
| Modulation strategy | The SINR (dB) requiring |
| BPSK | 6.549 |
| QPSK | 8.471 |
| QAM16 | 10.989 |
| QAM64 | 16.13 |
(3) TCP model
In method of the present invention, use TCP Reno algorithm, it is most popular algorithm in Transmission Control Protocol version.TCPReno algorithm comprises slow startup, Congestion Avoidance and re-transmission fast, fast quick-recovery stage.When a TCP session establishment gets up, we say that TCP is in slow start stage.In this stage, the double growth of the size of congestion window while often receiving an ACK acknowledge message.The size of congestion window is transmitting terminal to be received to the restriction of a transmitting terminal of the maximum amount of data that confirmation (ACK) can transmit to network before.Until the size of congestion window surpasses thresholding or detects when congested, stop carrying out slowstart algorithm, proceed to congestion avoidance phase.Congestion window size starts linear growth.When receiving terminal is received an out-of-sequence datagram, can beam back immediately a repeat ACK, the object of this ACK is to inform that transmitting terminal receives an out-of-sequence datagram and its desired sequence number of accepting is described.From the angle of transmitting terminal, repeat ACK may cause by many network problems.First, they are likely to cause because of packet loss.In the case, all data segments after this data segment all can trigger repeat ACK.Secondly, repeat ACK may be because network causes the rearrangement of data segment.Finally, repeat ACK is likely that ACK or data segment are caused by network copy.In addition, when receiving terminal partial or complete filled up sequence number vacancy and should send immediately an ACK, can notify more in time transmitting terminal like this, it is recovered rapidly from retransmission state.
Receiving that 3 repeat ACKs (are 4 continuous identical ACK, indicate that 1 data segment loses) time, TCP does not wait the overtime just re-transmission immediately of retransmission timer to it seems that the data segment of having lost enters the fast quick-recovery stage and carries out new transfer of data, at this moment retransmission timer duration doubles, transmission rate reduces by half, ever since in this stage until 1 non-repeat ACK arrive.Forward again afterwards the avoid congestion stage to, after timer expiry, then forward slow start stage to.Even if this strategy is good than early stage TCP version, when only having at least one lost package of recipient, efficiency is still very low.Therefore, in wireless network environment, its performance is poorer.
What the present invention proposed is a TCP sensing network coding method for more healthy and stronger random schedule more comprehensively.In this method, which coated coding the dynamic property (using the TCP model of B joint explanation) and the channel quality (using the channel model of C joint explanation) that consider TCP decide and use what data rate.Thereby this method can be known accurately any channel-changing and can respond fast and effectively the sender of TCP bag in unpredictable link condition.Especially, at transmitting terminal, establish TCP send window size for N, 1≤η < α < β≤N, η wherein, α and β are the parameters that determines equally TCP congestion window state.If n ∈ N is the state of current congestion window, β < n≤N, represents that TCP transmission rate is very high.Therefore, scheduler program can be ignored link quality distribution high channel rate coding mode (QAM64).The reason that can so do is if when TCP speed is very high, and bad channel quality and channel speed can be inevitably due to the congested packet losses that causes when low.The benefit of distributing in this case high channel speed is that the node that other link qualities are good can obtain medium fast.The advantage of so doing is to share by efficient resource.Yet transmission can cause high bit error rate on the channel of an employing high modulation strategy and bad channel quality.This just needs to adopt adaptive coding to guarantee this special bit error rate.And just in case because the reason expection recipient of bad channel quality has lost bag, the node that other links are good can listen to such bag and can be transmitted to expection recipient by network code.When α < n≤β, adopt minimum channel speed coded system QAM16, if channel quality is fine, can distribute QAM64.So do and can guarantee that TCP can utilize obtainable bandwidth fast.For η < n≤α, allocated channel rate coding mode is at least QPSK.When if channel quality becomes very good, can adopt the channel coding method with 1≤n≤η, as BPSK.
Regular, wireless link meeting deep fading, this just means that minimum modulation strategy all can not be used.In this case, allocated channel not.Therefore, do not transmit any data.So many benefits are saving powers and avoid impacting other node.Yet TCP can be overtime when can not receive acknowledge message ACK.Node does not transmit data and just means that neighbors can not receive that receiving report upgrades the information of monitoring bag, and at this moment the chance of coding will be little a lot.For fear of this situation, allow certain channel qualities such as delay to improve to recover transmission.In the time of bad channel quality, enabling to transmit, is also to receive report and monitor bag in order to provide to the good neighbors of link-quality.So can increase code machine meeting.On intermediate node, the bag of encoding or non-coding bag are all the data rates determining according to the TCP transmission rate of forwarding information packet header subscript knowledge.When having a code machine meeting, intermediate node selects one group of suitable bag to encode according to method discussed above.Notice that final one group of bag selecting may require different code rates to encode.In order to obtain best data rate, our strategy is the speed of selecting to require in this group bag the minimum local bag of speed.Even if this selection can not meet the requirement of the bag that those speed are high, but be to have considered that the dynamic of TCP and the requirement of link condition two aspects have guaranteed performance.
Adopted above-mentioned wireless network to realize the method that transmission control protocol sensing network coded scheduling is controlled, due to wherein based on existing feasibility study network code performance limited, utilized the chance dispatching algorithm in mobile radio network, on the intermediate node of wireless network, consider which decides aspect the dynamic of TCP and link condition two be coatedly encoded into an encoded packets and use what data rate coding, thereby can in unpredictable link condition, know accurately that thereby any channel-changing can send acknowledge message ACK fast and effectively to the sender of TCP bag, reduced network congestion, especially the present invention has considered that congestion window size (a TCP parameter) and the condition of wireless channel improve TCP transmission performance, thereby can make network have higher throughput thereby can make bandwidth be used more effectively, improved the utilance of bandwidth, can better utilize Radio Resource, stable and reliable working performance, the scope of application is comparatively extensive.
In this specification, the present invention is described with reference to its specific embodiment.But, still can make various modifications and conversion obviously and not deviate from the spirit and scope of the present invention.Therefore, specification and accompanying drawing are regarded in an illustrative, rather than a restrictive.
Claims (11)
1. in wireless network, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described method comprises the following steps:
(1) in Radio Network System, set up Wireless Network Coding model, wireless channel model and transmission control protocol model;
The described Wireless Network Coding model of setting up, comprises the following steps:
(11) in the intermediate node of Radio Network System, set up local data packet buffer, in described local data packet buffer, store this intermediate node from wireless network monitoring reception to packet and by this intermediate node oneself, produced and the packet at free interval;
(12) in the intermediate node of Radio Network System, set up lower-priority data packet buffer, in described lower-priority data packet buffer, store this intermediate node from wireless network monitoring reception to not need to send to the packet of other node;
The described wireless channel model of setting up, is specially:
According to following Formula wireless channel model P
e:
Wherein,
K
1and k
2be the factor of coding criterion, N
retransfor sending times, N
frfor the frame number of packet, L
frthe frame length of packet, BER is error rate;
The described transmission control protocol model of setting up, is specially:
Based on TCP Reno algorithm, set up transmission control protocol model;
(2) according to wireless channel model and transmission control protocol model, respectively the channel quality of Radio Network System and transmission control protocol dynamic property are carried out to evaluation process;
(3) according to the result of evaluation process, the channel speed coded system in Radio Network System is configured in real time;
(4) intermediate node in Radio Network System is determined the processing of encoding of one group of tcp data bag according to Wireless Network Coding Model Selection;
(5) described intermediate node responds the sender of this group tcp data bag, and the packet after coding is processed carries out forward process.
2. in wireless network according to claim 1, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described local data packet buffer is also carried out following processing operation:
(111) by described intermediate node institute monitoring reception to the processing of decoding of the packet crossed of coding;
(112) situation of the packet arriving according to this intermediate node institute monitoring reception creates and receives report, and shares to the node adjacent with this intermediate node.
3. in wireless network according to claim 1, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described carries out evaluation process to the channel quality of Radio Network System and transmission control protocol dynamic property, comprises the following steps:
(21) according to wireless channel model, obtain signal and interference and the noise ratio SINR of the channel of Radio Network System;
(22) at the sending node of Radio Network System, judge the relation between TCP congestion window state parameter η, α, β and the current state n of TCP congestion window responding, wherein:
1≤η < α < β≤N, N is the size of TCP send window.
4. in wireless network according to claim 3, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described configures the channel speed coded system in Radio Network System in real time according to the result of evaluation process, comprises the following steps:
(31) if β < is n≤N, TCP transmission rate is very high, and Radio Network System is configured to high channel rate coding mode;
(32), if α < is n≤β, Radio Network System is configured to minimum channel rate coding mode;
(33), if η < is n≤α, Radio Network System is configured to the coded system that channel speed is not less than QPSK;
(34) if 1≤n≤η is configured to Radio Network System the coded system that channel speed is not less than BPSK.
5. in wireless network according to claim 4, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described high channel rate coding mode is QAM64 coded system.
6. in wireless network according to claim 4, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described minimum channel rate coding mode is QAM16 coded system.
7. in wireless network according to claim 2, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described according to Wireless Network Coding Model Selection, determine the processing of encoding of one group of tcp data bag, comprise the following steps:
(41) described intermediate node is based on Wireless Network Coding model, and the reception report and the default screening rule that according to adjacent node, send screen received tcp data bag;
(42) described intermediate node determines according to the channel speed coded system of the instant channel condition of the TCP transmission rate of each tcp data bag, all relevant wireless links and configuration in real time one group of tcp data bag will encoding and process;
(43) to the processing of encoding of this group tcp data bag, and obtain corresponding coded data packet.
8. in wireless network according to claim 7, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described default screening rule comprises:
(411) bag being produced by described intermediate node oneself can not be encoded as one group of packet;
(412) having the packet that the identical next one jumps a little can not encode as one group of packet;
(413) if the next one of packet transmits the channel quality of link lower than the requirement of the coded system of lowest channel speed, by this data packet discarding.
9. in wireless network according to claim 7, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, described to the processing of encoding of this group tcp data bag, be specially:
With XOR bit arithmetic symbol, this group tcp data bag is encoded.
10. in wireless network according to claim 7, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that, the code rate that described carrying out coding is processed is for requiring the speed of this locality bag that speed is minimum in this group packet.
In 11. wireless networks according to claim 7, realize the method that transmission control protocol sensing network coded scheduling is controlled, it is characterized in that in the forwarding information packet header of described coded data packet, thering is local data package informatin, the recipient information of each local packets, the reception report information of this intermediate node, reporting quantities field and group/cording quantity field after coding.
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