CN101098173A - Method for dynamic regulating business service quality of transmission in wireless network - Google Patents

Abstract

The invention discloses a method for dynamically adjusting service quality transmitted in network, which arranges dynamic adjustment strategy in the network device with service transmission. And the method comprises that network device recognizes the priority of report in the transmitted report, according to the preset dynamic adjustment strategy, adjusting the priorities of all or part reports or/and throwing out all or part reports after preset transmission times. The invention can confirm the service quality of different services when transmits different services.

Description

Dynamically adjust the method for the QoS that transmits in the wireless network

Technical field

The present invention relates to the technology of transport service in wireless network, the method for the QoS (QoS) that transmits in particularly a kind of dynamic adjustment network.

Background technology

Over nearly 10 years, the wireless network that comprises wireless lan (wlan), wireless Mesh netword and mobile Ad hoc network has been obtained numerous achievements in research, wherein the research at medium access control (MAC) agreement mainly is to solve problems such as concealed terminal and raising access capability, the 802.11s agreement that above-mentioned network MAC agreement mainly contains 802.11e and customizing at present, and the double-channel scheme of MACA agreement, control channel and data channel division, based on the MAC agreement of directional antenna, based on the MAC agreement of transceiver etc.

The standardization body that two responsible video encodings are arranged in the world, one is the video coding expert group (VCEG) under the Union of International Telecommunication, another is the Motion Picture Experts Group (MPEG) under the International Standards Organization, the correlative coding standard that these two standardization bodies formulate has all obtained to use widely, H.261 standard has (video compression standard that is chosen to be video conference by Union of International Telecommunication), H.262 (this standard is just the same with MPEG-2, be the compression standard of VCEG with combined coding expert group (JVT) formulation of MPEG composition, H.262 what VCEG issued is, that MPEG issues is MPEG-2), H.263 (H.263+ this standard is had the enhancement mode version by the video compression standard that Union of International Telecommunication is chosen to be video telephone, H.263++), H.264 (this standard be in May, 2002 VCEG be the standard that interactive video communication of new generation is formulated).The standard that MPEG formulates has MPEG-1, MPEG-2, MPEG-4, MPEG-7 and MPEG-21, the MPEG-1 compression standard is adopted by VCD, the compression standard of MPEG-2 is that DVD adopts, MPEG-4 is the compression standard of formulating for the interactive multimedia communication, and MPEG-7 is the compression standard of formulating for the internet video retrieval.

H.26x, the compression standard that VCEG formulates all is at the single rectangular object video, and it pursues higher compression efficiency.MPEG-4 is based on a plurality of compressed encoding standards of looking audio object, and this is very suitable for the multimedia application on the Internet.

MPEG-4 has adopted the compression algorithm of content-based correlation.For compressing in the frame, utilize the correlation of image self mainly to take transition coding technology based on DCT (Discrete Cosine Transform), be called the I frame, be used to reduce spatial redundancy information; The compression algorithm of interframe mainly is at motion prediction and motion compensation, is called P frame or B frame, and wherein, what comprise in the P frame is the increment of present frame for forerunner's frame; The B frame is a color and background category information that constitutes on the picture.The I frame has important status as the reference frame, and the disappearance of reference frame will cause that the sequence of quoting this frame can not normally restore, and video quality is sharply descended.Therefore must take measures necessary to protect the I frame.MPEG-4 is based on object, and each scene is made up of the object video (VO) of absolute coding, and each VO is made of video object layer (VOL), and each VOL is made up of the object video platform of arranging in order (VOP).The cataloged procedure of each VOP and other standard such as MPEG-1, H.263 closely similar based on the frame level provide motion and text code to each VOP.MPEG-4 adopts fixedly GOP (Group ofPicture) structure, and the order of arrangement is generally: IBBPBBPBBPBB.

In 802.11 agreements, if a business does not obtain transmission opportunity in competition process, it can not abandoned on the MAC layer yet, but to make this business continue to participate in the competition, that is to say that a business can repeatedly participate in the competition within the specific limits, thereby obtain transmission opportunity, generally the number of times that participates in the competition of this business is 7 times.This transmission means of competing has again guaranteed reliability of service transmission to a certain extent, but for the business that real-time is had relatively high expectations, can increase its time delay to a certain extent.

In order in 802.11 agreements, to support QoS, IEEE 802 worker's group groups have been formulated the MAC agreement of a kind of 802.11e of being called, multiple step format coordination function (DCF) agreement in original 802.11 is strengthened, the multiple step format coordination function (EDCF) that is called enhancing, the 802.11s standard of formulating has been continued to use EDCF mechanism, but renames as the distributed coordination access (EDCA) of enhancing.802.11e/802.11s realize QoS is supported by introducing class of service (TC).EDCF/EDCA provides 4 access classification (AC) differentiable, distributed access channel, corresponding different respectively TC for website.Have 4 kinds of AC to support user's priority (UP) in each website, one of them AC can apply one or more UP for the user.A website need insert formation according to the AC of data to be transferred frame, and table 1 has provided the mapping relations of TC to AC.

Table 1

Each AC is the enhancing variant of DCF, uses one group of EDCF/EDCA channel access parameter to remove to compete send opportunity (TXOP), and TXOP represents to work as a period of time interval that a website is got permission to initiate to the EDCF/EDCA channel transmission.The designated littler competition window of AC (CW) with high priority, to guarantee that high priority preferentially sends than the AC of low priority, to obtain this access preferential by AC being provided with CW gauge (minimum competition window: CWmin[AC], maximum contention window: CWmax[AC]).Distinguish in order further to carry out QoS, different AC adopts different frame periods (IFS).802.11e/802.11s middle regulation, if website will begin the process of transmitting of a Frame, must satisfy DIFS in the time channel keep idle; In EDCF/EDCA, DIFS is by AIFS[AC] replace general AIFS[AC] 〉=DIFS.AIFS[AC] computing formula is as follows:

AIFS[AC]＝SIFS+AIFSN[AC]×aSlotTime (1)

AIFSN[AC wherein] be a positive integer, aSlotTime is the slot length relevant with physical layer.

If one is used the website of EDCF/EDCA to find the EDCF/EDCA channel busy when being ready for sending, then begin to postpone sending, up to the EDCF/EDCA channel idle, postponement is waited for AIFS[AC after finishing again] time, start a backoff procedure then.Backoff interval is [0, CW[AC]] an interior random number.CW[AC] be calculated as follows:

CW[AC]=min ((former CW[AC]+1) * 2-1, CWmax[AC]) (2)

The sending order timing diagram of EDCF/EDCA frame as shown in Figure 1.

In an EDCF/EDCA website, each AC is similar to a virtual website, by competing access channel independently, also usually claims AC to be one and keeps out of the way entity.When listening to AIFS[AC] channel idle in the time, the just backoff procedure of startup oneself.When having a plurality of AC to be ready for sending simultaneously in the website, will produce so-called " virtual collision ", the way of dealing with problems is that the website that has limit priority will obtain TXOP, and sends and need keep out of the way as conflict has really taken place on channel from the data of low priority AC.Be illustrated in figure 2 as with reference to implementation model.

802.11e/802.11s realized support to QoS by introducing TC, the transmission of Medium Access Control (MAC) Service Data Unit (MSDU) realizes by a plurality of transmission processes in the website, each transmission process is all used the parameter relevant with TC, and typical qos parameter is as shown in table 2.

AC	CWmin	CWmax	AIFSN
				0 1 2 3	CWmin CWmin (CWmin+1)/2-1 (CWmin+1)/4-1	CWmax CWmax CWmin (CWmin+1)/2-1	2 1 1 1

Table 2

802.11e/802.11s EDCF/EDCA has defined a kind of optional delivery plan, is referred to as contention free burst (CFB, Contention Free Burst).If website is provided with this function, obtain TXOP by competition, it can send a plurality ofly from the same Frame of keeping out of the way in the entity during this period continuously so, and the time interval between these Frames and the acknowledgement frame is SIFS.But stipulate that total channel occupancy time can not surpass TXOP, also will discharge channel even without using up whole TXOP.Represented among Fig. 3 that in a TXOP transmission of two Frames can see that therefrom the actual channel holding time is less than TXOP.Because there is this restriction, so when adopting the CFB function, can't have a strong impact on the delay performance of network.When selecting the TXOP that is fit to, also can increase the total throughput of system, satisfy the requirement of other performance index simultaneously.

Though EDCF/EDCA has proposed the thought of service priority and provided priority parameter is set at present, thereby provide QoS to guarantee to different business.But the realization of this priority thought is a prerequisite in the sacrifice mode, and promptly the business of high priority obtains the business of TXOP much larger than low priority, and this has lost the fairness of Network Transmission to low priority traffice.

Along with WLAN, WMN and mobile Ad hoc networks development and the demand that merges with 3G network, in the access control of MAC layer, must introduce a large amount of multimedia services, as voice Internet protocol (VoIP) business and real-time video traffic etc., these business are had relatively high expectations to real-time, therefore must give higher priority.But when network load is big, in the time of a large number of services intensified competition just, the particularly existence of real-time video traffic, when further worsening the network competition because of its professional particularity own, competition has consumed a large amount of network bandwidth resources, even high-priority service also begins frequent re-transmission, real-time has lost assurance, caused low priority traffice can't obtain TXOP simultaneously, a large amount of packet losses have a strong impact on the QoS that transmits all kinds of business in the network.

The another kind of technical scheme that transmits service with different priority levels also is provided here.In this scheme, mainly be the scheme that proposes a kind of dynamic value at CWmax and these two parameters of CWmin.

Dynamically adjust the CWmax scheme and be meant the size of reasonably adjusting its CWmax at an AC, establish here:

AC[i]: a certain class AC;

I: span is 0 to 7, and limit priority is 7, and minimum is 0;

CWmax[i]: AC[i] CWmax;

CW[i]: AC[i] CW;

NewCWmax[i]: dynamic adjusted AC[i] CWmax.

The key issue of dynamically adjusting the CWmax scheme is if the CWmax[i that establishes] too little, the AC back off time is just very short so, and the number of times of keeping out of the way will increase, and in competition more relatively collision will take place like this, causes the increase of time-delay and shake.If the CWmax[i that establishes] too big, the AC back off time again can be long, and it is too small to keep out of the way number of times, particularly in the system of high traffic load, may cause bigger time-delay and shake.So rationally adjust CWmax[i] size to adapt to different traffic loads, can reduce to a great extent the time-delay and the shake.

In 802.11e/802.11s, each AC has a fixing CWmax and CWmin.After transmission was finished, the CW of AC can adjust, and adopted formula CW[i]=min ((former CW[i]+1) * 2-1, CWmax[i]).At this formula, this scheme is before CW adjusts, and recomputates to produce a new CWmax[i], and the newCWmax[i of this new generation] be exactly the value of a continuous dynamic change, it is as follows that it calculates sampling process, and insert successfully back two kinds of situations with competition after being divided into the competition access failure.

The adjustment of competition failure back CW

f _Curr ^jThe average collision rate of network; f _Avg ^j: instantaneous collision rate.P: mobile node;

Numb (date_sentj[p]): in the j section time, the number-of-packet that mobile node p sends;

Numb (collisionsj[p]): in the j section time, the number-of-packet of the competition collision that mobile node p takes place; DCWmax[i]: the variable in the calculating.

After the competition failure, newCWmax[i] value want complicated relatively, at first introduce the notion of average collision rate f, each node can calculate the average collision rate f of network in time T _Curr ^jf _Curr ^jCan obtain by following formula: $f_{\mathrm{curr}}^j=\frac{\mathrm{Numb}\left(\mathrm{collisionsj}\right[p\left]\right)}{\mathrm{Numb}(\mathrm{data}\_\mathrm{sentj}[p\left]\right)}$

In scheme, expectation can obtain f by calculating _Avg ^jEstimated value, suppose the factor-alpha of an obeys index distribution, the excursion of α is [0,1], then $f_{\mathrm{avg}}^j=(1-\mathrm{\α})\×f_{\mathrm{curr}}^j+\mathrm{\α}\×f_{\mathrm{avg}}^{j-1},$ Obtaining f _Avg ^jAfter, just can further calculate newCWmax[i by following formula].Establish an intermediate variable DCWmax[i that in calculating, will use earlier], the formula that calculates this variable is as follows:

$\mathrm{DCW}\max \left[i\right]=(8-i)\×{\left(f_{\mathrm{avg}}^j\right)}^{2i-9}\×\left(\mathrm{CW}\max \right[i]-\mathrm{CW}\min [i\left]\right)$

newCWmax[i]＝2 ^10-i×CWmin[i]+DCWmax[i]

But, newCWmax[i] and be subjected to the restriction of physical layer, therefore:

newCWmax[i]＝min(newCWmax[i]，maxPHYCWlim)

Wherein maxPHYCWlim is the maximum CW that physical layer can allow.

The adjustment of CW after transmission is finished

Through top calculating, can obtain a node after the competition bust this, how its maximum CW obtains optimum setting, and obtain next step and keep out of the way window CWnew[i]=max[newCWmax[i], 2 * CWprev[i]+1], the CWnew[i that obtains here] be node competition failure back the CW value that should adjust.When node completed successfully a transmission, how this is provided with it was kept out of the way window so, specifically described below.

A node must provide TXOP for continuously such business in order to guarantee professional QoS, so at this moment just must adjust the CW of AC, and scheme provides different CW account forms at different AC, and these calculating are still based on EDCF/EDCA's.On calculating, divide concrete computing formula such as table 3 according to the priority of AC.

Class of service	Access category	The CW computing formula
			1 1 2 2 3 4 5 5 5 6 7 7	0 0 1 2 3 4 5 5 5 6 7 7	Min ((former CW[i]+1) * 2-1, CWmax[i]) min ((former CW[i]+1) * 2-1, CWmax[i]) min ((former CW[i]+1) * 2-1, CWmax[i]) min ((former CW[i]+1) * 2-1, CWmax[i]) min ((former CW[i]+1) * 2-1, CWmax[i]) CWmin[i] CWmin[i] CWmin[i] CWmin[i] CWmin[i] CWmin[i] CWmin[i]

Table 3

The business that can clearly see high priority from formula table 3 has a smaller CW, can guarantee the acquisition TXOP that it is continuous, finishes stable, a professional transmission efficiently.

This scheme still is based on the improvement project of 802.11e, is equally to have kept priority, also is that purpose is will reach the business that makes high priority can access transmission channel the priority consideration of putting in the first place in the scheme implementation procedure.As seen this scheme is not also considered the transmission balance of each business in professional type and the network, can not solve the competitive advantage that under the situation of limited bandwidth, how to effectively reduce high-priority service, can't guarantee the competition transmission of low priority traffice, can not make in the whole network each business that a reasonably transmission balance is arranged, influence the QoS that transmits all kinds of business in the network.

Summary of the invention

In view of this, main purpose of the present invention is to provide the method for the QoS of survice that transmits in a kind of dynamic adjustment network, and this method can guarantee the QoS of different business when the transmission different business.

According to above-mentioned purpose, technical scheme of the present invention is achieved in that

The method of the QoS that transmits in a kind of dynamic adjustment network is provided with dynamic adjustment strategy in the network equipment of transport service, this method also comprises:

Priority of messages in the transport service is wanted in network equipment identification, adjusts all or part of priority of messages in this business or/and abandon all or part of message in this business behind the number of transmissions of setting according to the dynamic adjustment strategy that is provided with.

Describedly adjust all or part of priority of messages in this business or/and behind the number of transmissions of setting, abandon the process of all or part of message in this business and be according to the dynamic adjustment strategy that is provided with:

Two threshold value P1 and P2 are set,

When the bust this number of wanting transport service greater than threshold value P1 during smaller or equal to threshold value P2, this professional priority that raises reduces part priority of messages in other business of the current transmission of the network equipment; When the bust this number of wanting transport service during, this professional priority that raises, part priority of messages in other business of the current transmission of the network equipment is reduced and behind the number of transmissions of setting, abandon automatically greater than threshold value P2.

Threshold value P1 is 100, and threshold value P2 is 200.

Described losing is that number of retransmissions is set to 0.

Described abandoning is to adopt the mode that reduces number of retransmissions to carry out.

Described two threshold value P1 and P2 determine according to the network analog result;

The number of transmissions of described setting is determined according to the network analog result.

Described business is the special transmission of constant proportion CBR business, speech business or data service, and the part message is the non-key frame in other business in other business of the current transmission of the described network equipment.

Non-key frame in described other messages is the B frame in the special transmission of the no-load voltage ratio VBR business.

From such scheme as can be seen, the present invention is provided with dynamic adjustment strategy in the equipment of transmission miscellaneous service, want the part or all of priority of messages in the transport service or/and behind the number of transmissions of setting, abandon all or part of message in this business according to set dynamic adjustment strategy adjustment, thereby make the present invention when the transmission different business, guarantee the QoS of different business.Further, the present invention is owing to dynamically adjust the part or all of priority of messages in the transport service or/and abandon all or part of message in this business behind the number of transmissions of setting, can reduce the competition conflict between each business, improve the bandwidth availability ratio of wireless network.Not only guarantee the high real-time transmission of the business that the high priority real-time is high, and guaranteed effective transmission of low priority traffice in the wireless network.Particularly in the network that speech business and video traffic are only arranged, adopt method provided by the invention can increase the number of users of speech business.

Description of drawings

Fig. 1 is the sending order timing diagram of EDCF/EDCA frame;

Fig. 2 is that EDCF/EDCA is with reference to implementation model;

Fig. 3 is two sequence timing figure that Frame sends in the prior art;

Fig. 4 dynamically adjusts the method flow diagram of the QoS of survice that transmits in the network for the present invention;

Fig. 5 is the schematic diagram of the embodiment of the invention;

Fig. 6 is the implementation procedure figure of the embodiment of the invention;

Fig. 7 is a wireless Mesh netword emulation topology diagram of the present invention;

Fig. 8 is the total throughput comparative analysis curve chart of network after the enforcement scheme provided by the invention;

Fig. 9 is a speech business throughput comparative analysis curve chart after the enforcement scheme provided by the invention;

Figure 10 is a VBR business throughput rate comparative analysis curve chart after the enforcement scheme provided by the invention;

Figure 11 is a CBR business throughput rate comparative analysis curve chart after the enforcement scheme provided by the invention;

Figure 12 is a VBR traffic delay comparative analysis curve chart after the enforcement scheme provided by the invention;

Figure 13 is for implementing after the scheme provided by the invention when network only has voice service and VBR professional voice service throughput comparative analysis curve chart;

Figure 14 is for implementing after the scheme provided by the invention when network only has voice service and VBR professional VBR business throughput rate comparative analysis curve chart.

Embodiment

In order to make the purpose, technical solutions and advantages of the present invention clearer, below lift specific embodiment and, the present invention is described in more detail with reference to accompanying drawing.

The present invention can accomplish to be associated with the characteristic of service with different priority levels for the access control that realizes the MAC layer, in transmission course, guarantee the qos requirement of service with different priority levels, thereby guarantee the reasonable fairness of priority service, the business that real-time is had relatively high expectations reduces time-delay, and the less demanding business of real-time obtains transmission bandwidth.

In traditional 802.11e and the present 802.11s that is customizing, because the business of high priority is occupied great advantage in competition, increase along with traffic load in the network, network is owing to professional competition has consumed a large amount of bandwidth on the one hand, on the other hand because limited bandwidth, make and to obtain transmission bandwidth as the special transmission of constant proportion (CBR) business by low priority traffice.The present invention is directed to the professional characteristic of the special transmission of no-load voltage ratio (VBR), clocklike abandon some messages of its business under certain condition and reduce and retransmit professional number of times, reduce the expense of competition, improve professional real-time own, meanwhile, give the CBR service access chance in the network, the cost of its sacrifice is dwindled, guarantee under the network state of high load capacity, still can reach a reasonable QoS and guarantee, and the speech business throughput of also giving high priority is with to a certain degree raising.

In order to satisfy the QoS of service with different priority levels when transmitting in the network, improve the throughput of network, the present invention adopts dynamic priority mode and restriction re-transmission mode to transmit service with different priority levels.

Fig. 4 is the method flow diagram that the present invention dynamically adjusts the QoS of survice that transmits in the network, supposes that a business has a plurality of messages, and each message has different priorities according to the difference of its importance, and its concrete steps are:

Step 400, dynamic adjustment strategy is set in network.

Step 401, when transport service, the recognition of devices in the network goes out a plurality of priority of messages that this business comprises.

Equipment in step 402, the network is adjusted a plurality of priority of messages that this business comprises or/and the re-transmission of message is done dynamically to adjust according to dynamic adjustment strategy is set.

In the present invention, it is exactly in order to abandon the part message that this business comprises that the re-transmission of message is done dynamically to adjust, promptly abandon all or part of message in this business behind the number of transmissions of setting, the mode that abandons is to reset the number of retransmissions of all or part of message in this business.

Below lifting specific embodiment describes.

Characteristics such as along with the digitlization and the networking of conventional video industry, the demand of carrying out video transmission on network is more and more, and video traffic has real-time and has relatively high expectations, and the big and occupied bandwidth resource of data transmission rate is many.In wireless network, be the video traffic main standard at present with the MPEG-4 compression coding mode.Stipulate in the MPEG-4 standard: piece image is made up of a plurality of Frames, there is certain dependence between each Frame, general piece image is made up of the IBBPBBPBBPBB frame structure, wherein the I frame is as the reference frame, the disappearance of reference frame information will cause that the sequence of quoting this frame can not normally restore, and video quality is sharply descended; I frame or P frame that the P frame relies on the front use prediction algorithm to form, and what it comprised is the increment of present frame for forerunner's frame, is a very crucial Frame; The B frame is by contrast, and just seeming is not very important, and it mainly is a color and background category information that has constituted on the picture, under the limited situation of the network bandwidth, can abandon this Frame on one's own initiative by certain principle.

In the present invention, different Frames is provided with different priority, thereby alleviates the pressure that low priority can't obtain the network bandwidth to a certain extent.

The schematic diagram of the embodiment of the invention as shown in Figure 5.

Suppose to be provided with dynamic adjustment strategy in the equipment in network, this equipment normal transmission CBR business, VBR business and speech business, should dynamically adjust strategy starts when CBR service competition mortality reaches certain thresholding, this thresholding is divided into two situations, a kind of situation is if the professional transmission failure rate of CBR when higher, when just network traffic load is big, the professional bust this number of CBR＞100 and≤200 o'clock, only start the dynamic priority mode of dynamically adjusting in the strategy; Another kind of situation is when the professional bust this of CBR is very high, and promptly bust this number＞200 of CBR business o'clock then start the dynamic priority mode and limit the re-transmission mode.In the present invention, should dynamically adjust decision threshold that strategy starts obtains by network analog repeatedly, promptly when the CBR service competition frequency of failure reaches a thresholding, illustrate that at this moment network load has reached certain degree, must start dynamic adjustment strategy.It is simply effective that this dynamically adjusts tactful start-up criterion, and realizability is very high.

When the Network initialization, the priority of voice service is made as 0 for the highest, the priority of VBR business is made as 1 for time high, the priority of CBR business is minimumly to be made as 2, the competition the number of transmissions of each business is 4 times, promptly refer to when the service competition transmission channel,, then carry out 4 constantly competitions again if can not be successful.

The implementation process of the embodiment of the invention as shown in Figure 6.

After dynamically adjusting the strategy startup, at first miscellaneous service is through the frame recognition function of MAC layer, and the miscellaneous service that obtains receiving is the Frame of which kind of type, and identification information is inserted in the mac layer frame control field.Then, VBR priority professional and the CBR business no longer is during according to the network initial launch, changeless by the priority of each professional type setting, that is to say that the priority that the B frame of VBR business has is not 1, the priority that the CBR business has is not 2, but each Frame in the business is reset.Specific implementation is: when the professional bust this number of CBR＞100 and≤200 the time, be not reduced to 2 in the VBR business with competitive channel at this moment for the B frame priority of key frame, the priority of the CBR business that participates in the competition is equally risen to 1, just unessential Frame B frame priority in the VBR business and this CBR service priority that participates in the competition are constantly exchanged.B frame in the VBR business is because the reduction of priority like this, in competition, just lost original advantage, the chance that competition is obtained channel has given CBR business, thereby has guaranteed the professional acquisition of CBR transmission bandwidth to a certain extent, and then has increased the access capacity of network.

But under the very high situation of network traffic load, bust this number＞200 of CBR business o'clock, because the employing of dynamic priority technology, make the B frame of VBR business often can not get transmission opportunity when once competing, and will continue on channel, to be at war with, but the VBR business is that a class is to very sensitive business of time, if the picture that the user sees can not get upgrading in a period of time, generally all can disconnect existing connection, again make a call, B frame grouping once sends unsuccessful and continues to repeat the competitive channel resource and just lose meaning in the VBR business like this.At this situation, the present invention just adds the competition number of retransmissions mode of restriction VBR business on the dynamic priority mode, if promptly the professional B frame of VBR once compete unsuccessful after, just change the VBR service competition number of retransmissions on the MAC layer into 0, no longer allow this grouping reenter channel competition, automatically abandon this and be not the B frame of key frame, make its packet loss by force.So originally, the piece image of 12 frames may just only be the 5-7 frame what user side was received, and the reduction of frame number herein can't influence user's video calling time-delay, only is the decline that has caused image quality.Thereby the present invention improved the efficiency of transmission of this VBR business to a certain extent, strengthened the real-time of VBR business, and improved the transmission opportunity of CBR business, guaranteed the qos requirement of non-real-time service.

Realization of the present invention makes 802.11e/802.11s press close to business more, lay the foundation for WLAN, wireless Mesh netword and mobile Ad hoc network and the network integrations such as NGN, 3G, make the priority parameters setting in original cavity more flexible, not only improved the real-time of real time business, also increased simultaneously the transmission opportunity of non-real-time service, guarantee the fairness of Network Transmission service with different priority levels, especially under the bigger situation of network load, more can embody advantage of the present invention.

For the beneficial effect that shows that the present invention brings, below be example with MPEG-4 encoding stream medium, be given in network the statistic property result who obtains in the emulation under voice service, VBR business and the data service condition is arranged, resulting result is an example with most typical high-load condition, points out the optimization that the present invention brings for network; Simultaneously in order to show that the present invention can be brought by network provides more voice user to insert, be example still with MPEG-4 encoding stream medium, being given in network has only under voice service and the VBR professional qualification and (has only the data service of minute quantity, substantially can ignore, but start thresholding in order to obtain strategy, so only add minute quantity) the statistic property result that obtains in the emulation, resulting result is an example with most typical high-load condition, points out the optimization that the present invention brings for network.

At first, simulated environment of the present invention is set, and as shown in Figure 7, Fig. 7 is a wireless Mesh netword emulation topology diagram of the present invention: comprise access point (AP), website 1, website 2 and website n, wherein, website 1 to n is to AP transmission VBR business, speech business and data service.

Table 4 is the parameter and the parameter type of site configuration.

Parameter name	Parameter type
		channel type	Channel/WirelessChannel
radio-propagation model	Propagation/TwoRayGround
		network interface type	Phy/WirelessPhy
MAC type	MAC/802_11e/802_11s
		interface queue type	Queue/DTail/PriQ
routing protocol	AODV

Table 4

The business that table 5 is provided with for website.

Table 5

Table 6 is a physical layer parameter.

Parameter	Numerical value
		SlotTimc CCATime RxTxTurnaroundTime SIFSTime PreambleLength PLCPHeaderLength PLCPDataRate PropagationDelay basicRate dataRate	9us 4us 2us 16us 120bits 40bits 6Mbit/s 1us 1Mbit/s 1Mbit/s

Table 6

The meaning of each parameter is as follows in the table 6:

SlotTime: slot time, MAC defines IFS between the various frames with it;

During access service, the judgement business is busy or idle needed minimum time to CCATime:CCA mechanism in each time slot;

RxTxTurnaroundTime: transfer needed maximum time of transmission first sign-on PHY to from reception;

SIFSTime:Short IFS, short interFrameGap;

PreambleLength: the preamble length of current PHY;

PLCPHeaderLength: the PLCP head length degree of current PHY;

PLCPDataRate: the transmission rate of PLCP head in medium of current PHY;

PropagationDelay: transmission signals desired time from the cell site to the receiving station;

BasicRate: the packet header of transferring data frames and control, the speed that management frames adopted for the network that makes simulation reaches capacity fast, thereby are made as 1Mbit/s in this emulation;

DataRate: the speed that payload adopted of transferring data frames for the network that makes simulation reaches capacity fast, thereby is made as 1Mbit/s in this emulation.

Have in voice service, VBR business and the emulation of data service high load capacity at network, setting simulation time is 10 minutes, 12 sending nodes, an AP, each sending node all has 3 kinds of business in the network, be respectively voice service, VBR business and data service, wherein voice service adopts the ON/OFF model modeling; VBR is professional to adopt the modeling of MPEG-4 mode, and strictly observes MPEG-4 encoding compression framing method; Data service then uses the original CBR service source of NS2 to produce, and service parameter all is provided with according to predetermined data service parameter rule in the internet; Only have in voice service and the professional high load capacity emulation of VBR at network, setting simulation time is 1 minute, 12 sending nodes, an AP, each sending node all has 2 kinds of business in the network, is respectively voice service, VBR business, and wherein voice service adopts the ON/OFF model modeling; VBR is professional to adopt the modeling of MPEG-4 mode, and strictly observes MPEG-4 encoding compression framing method.

After adopting the present invention, because under certain conditions, reduced the priority of VBR business, reduced the bandwidth consumption that access contention brought to a certain extent, the dynamic priority that while is dynamically adjusted in the strategy is adjusted being used in combination of mode and dynamic re-transmission mode, the professional number of retransmissions of VBR is reduced, initiatively abandoned some unessential Frame, this has reduced the competition bandwidth consumption that re-transmission is brought again to a certain extent, thereby can from Fig. 8, can clearly see the raising of the total throughput of network, wherein, the total throughput of network of scheme provided by the invention is not adopted in 3 expressions; The total throughput of network after the dynamic priority mode in the 2 expression employings scheme provided by the invention; The total throughput of network after 1 expression adopts dynamic priority mode in the scheme provided by the invention in conjunction with restriction re-transmission mode.

The throughput that Fig. 9 has described voice service under the voice service throughput that adopts under the dynamic adjustment strategy provided by the invention and the 802.11e/802.11s relatively.As we can see from the figure, use voice service (representing with 1 among the figure) throughput of dynamic adjustment strategy provided by the invention the highest, and it is less to fluctuate, this is because the reduction of VBR service competition makes voice service have bigger advantage to obtain the network bandwidth.Simultaneously, be that each curve has a fluctuation about 20-30s on can also discovery figure in the time, this fluctuation is to cause intensified competition that the channel available bandwidth is reduced because a large number of services starts, throughput sharply descends; But adopted its setback of curve of dynamic adjustment strategy provided by the invention less, because this finds that constantly the network bandwidth reduces, optimisation strategy promptly starts, and rapidly service competition is reduced, and has protected available transmission bandwidth.Wherein, 3 expressions is the curve chart that does not adopt scheme transmitting voice service provided by the invention; 2 expressions be the curve chart that adopts dynamic priority mode transmitting voice service in the scheme provided by the invention.

Figure 10 has shown the packet loss of Frame on different levels that makes the VBR business with method provided by the invention really, article three, the curve setback maximum (representing with 3 among the figure) of 802.11e/802.11s in the curve, can draw thus under the situation of bandwidth anxiety, professional its real-time of the VBR under the 802.11e/802.11s can not get guaranteeing at all; And adopted the VBR business (representing with 2 lines among the figure) of dynamic priority mode provided by the invention because the reduction of some Frame priority, make number of retransmissions increase, only need once competition just can insert by original same class, become and to carry out 6-7 unwarranted competition re-transmission, so the real-time of its VBR business has also lost certain guarantee; But the mode (representing with 1 among the figure) that has adopted dynamic priority mode provided by the invention and dynamic re-transmission mode to combine, initiatively abandon carrying out 6-7 unwarranted competition re-transmission VBR Frame, like this when the user perceives the image quality decrease of oneself watching, can disconnect connection voluntarily, again make a call, therefore this programme has not only improved the efficiency of transmission of VBR business, also improved simultaneously its real-time, certainly inevitably lost the picture quality of VBR business, thereby made throughput that certain decline be arranged.But this when being lost in network condition and worsening, be very important.

Figure 11 embodies the deterioration result of CBR business under the 802.11e/802.11s clearly, and it can not get transmission opportunity substantially when the network bandwidth is not enough for this non real-time business, and throughput is 0 substantially.And rationally effectively " sacrifices " of the professional because VBR business of the CBR that has adopted this programme makes the CBR business throughput rate rise significantly, thus the active of the VBR business picture viewing effect loss of paying be useful also be necessary.Wherein, 2 expressions is the curve chart that the dynamic priority mode is transmitted the CBR business in the employing scheme provided by the invention; 1 expression be adopt dynamic priority mode in the scheme provided by the invention and dynamically the mode that combines of re-transmission mode transmit the curve chart of CBR business; The curve chart of scheme transmission CBR business provided by the invention is not adopted in 3 expressions.

After having adopted the present invention as can see from Figure 12, the time delay of VBR business has had very big improvement.Wherein the mode that dynamic priority mode and dynamic re-transmission mode combine in the 1 expression employing scheme provided by the invention is transmitted the delay figure of VBR business; 2 expressions be to adopt dynamic priority mode in the scheme provided by the invention to transmit the delay figure of VBR business; 3 expressions be the delay figure that does not adopt scheme provided by the invention transmission VBR business.

As can be seen from Figure 13, adopted the technology of the present invention when in network as only existing voice service and VBR professional after, the throughput of voice service has had very big improvement.Wherein the throughput curve chart of voice service of the present invention is not adopted in 3 expressions, and its throughput mean value is 9.53kbit/s; 2 expressions be to adopt dynamic priority mode transporting speech business throughput rate curve chart in the scheme provided by the invention, its throughput mean value is 16.69kbit/s, than not adopting the present invention to improve 75.11%; 1 expression be to adopt the dynamic priority mode in the scheme provided by the invention and the dynamic curve chart of the mode transporting speech business throughput rate that combines of re-transmission mode, its throughput mean value is 18.72kbit/s, than not adopting the present invention to improve 96.44%.

As can be seen from Figure 14, when in network as only existing voice service and VBR professional, adopted the technology of the present invention after, the throughput of VBR business has had certain decline.Wherein the throughput curve chart of VBR business of the present invention is not adopted in 3 expressions, and its throughput mean value is 10.93kitb/s; 2 expressions be to adopt in the scheme provided by the invention the dynamic priority mode to transmit VBR business throughput rate curve chart, its throughput mean value is 10.44kbit/s, than not adopting the present invention only to descend 4.5%; 1 expression be adopt dynamic priority mode in the scheme provided by the invention and dynamically the mode that combines of re-transmission mode transmit the curve chart of VBR business throughput rate, its throughput mean value is 9.11kbit/s, than not adopting the present invention to descend 16.65%.

We can also find from Figure 13 and 14, if (data service seldom when network only has voice service and VBR business, substantially can ignore), after having adopted the technology of the present invention, though can bring decline seldom to the throughput of VBR business, but the throughput that but can bring voice service improves in a large number, thereby can allow more voice user join network.

In based on the emulation that the present invention implemented, realized the modeling that each is professional, and simulated the network condition under the multiple condition that the gained result has all verified feasibility of the present invention and validity.

The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being made within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1, the method for the QoS that transmits in a kind of dynamic adjustment network is characterized in that, dynamic adjustment strategy is set in the network equipment of transport service, and this method also comprises:

Priority of messages in the transport service is wanted in network equipment identification, adjusts all or part of priority of messages in this business or/and abandon all or part of message in this business behind the number of transmissions of setting according to the dynamic adjustment strategy that is provided with.

2, the method for claim 1 is characterized in that, describedly adjusts all or part of priority of messages in this business or/and abandon the process of all or part of message in this business be behind the number of transmissions of setting according to the dynamic adjustment strategy that is provided with:

Two threshold value P1 and P2 are set,

When the bust this number of wanting transport service greater than threshold value P1 during smaller or equal to threshold value P2, this professional priority that raises reduces part priority of messages in other business of the current transmission of the network equipment; When the bust this number of wanting transport service during, this professional priority that raises, part priority of messages in other business of the current transmission of the network equipment is reduced and behind the number of transmissions of setting, abandon automatically greater than threshold value P2.

3, method as claimed in claim 2 is characterized in that, threshold value P1 is 100, and threshold value P2 is 200.

4, method as claimed in claim 2 is characterized in that, described losing is that number of retransmissions is set to 0.

5. method as claimed in claim 2 is characterized in that, described abandoning is to adopt the mode that reduces number of retransmissions to carry out.

6, method as claimed in claim 2 is characterized in that, described two threshold value P1 and P2 determine according to the network analog result;

The number of transmissions of described setting is determined according to the network analog result.

7, method as claimed in claim 2 is characterized in that, described business is the special transmission of constant proportion CBR business, speech business or data service, and the part message is the non-key frame in other business in other business of the current transmission of the described network equipment.

8, method as claimed in claim 7 is characterized in that, the non-key frame in described other messages is the B frame in the special transmission of the no-load voltage ratio VBR business.

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