CN102685468B - Method and device for transmitting video packets - Google Patents

Abstract

The invention provides a method and a device for transmitting video packets. The method includes the steps: determining the priority level of the video packets and estimating transmission delay of the video packets; distributing counters for the video packets and determining initial values of the counters according to the priority level of the video packets and/or the transmission delay of the video packets; and transmitting the video packets according to count values of the counters and adjusting count values corresponding to the video packets which are not transmitted. By the aid of the method and the device, more important video packets in video data can be ensured, so that video transmission quality is improved.

Description

The transmission method of video packets and equipment

Technical field

The present invention relates to wireless communication technology, relate in particular to a kind of transmission method and equipment of video packets.

Background technology

WLAN (wireless local area network) (Wireless Local Area network, WLAN) conventionally adopt distributed coordination function (Distributed Coordination Function, DCF) agreement, according to DCF agreement, each node in network is avoided the competitive access wireless channel of mode of (Carrier SenseMultiple Access with Collision Avoidance, CSMA/CA) with the access/conflict of carrier sense multiple spot.The flow process of competitive access wireless channel roughly comprises: when node has data to send, first carry out channel and intercept, if channel idle waits for that distributed frame spacing (DistributedInterframe Space, DIFS) sends data after the time; If channel busy, starts backoff counter, the initial value of backoff counter is a value of getting at random on interval [0, W], and W is called as competition window, and the value of W is dynamically to change, the min-window value W of in-system define _minwith max-window value W _maxbetween.Continue afterwards to intercept channel, often listen to channel idle one time, the value of backoff counter subtracts one, if listen to channel busy, keeps the value of backoff counter constant.When the value of backoff counter is kept to 0, show that this node competes successfully, start to send data.

In wlan network, in order to support service quality (Quality of Service, the QoS) demand of application in real time, enhancing distributed channel access (Enhanced Distributed ChannelAccess, EDCA) agreement has been proposed.The access style (Access Category, AC) of having introduced 4 different priorities in EDCA agreement, is respectively AC_VO, AC_VI, AC_BE and AC_BK.Different AC adopts different access parameters, and access parameter for example comprises min-window value W _minwith max-window value W _max.

While adopting wlan network transmission of video bag, can calculate the probability of the video packets of every type in prior art, the probable value obtaining according to dynamic calculation, is mapped to video packets in different AC queues.But, this mode can not embody the character of video packets itself, can not guarantee that important video packets is preferentially transmitted, and the video packets that for example priority is high is not necessarily preferentially sent, or may send the video packets that exceeds delay requirement, thereby reduce the quality of transmission of video.

Summary of the invention

The embodiment of the present invention provides a kind of transmission method and equipment of video packets, in order to improve the quality of transmission of video.

The embodiment of the present invention provides a kind of transmission method of video packets, comprising:

Determine the priority of video packets, and the transmission delay of estimation video packets;

For video packets is distributed counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets;

According to the count value transmission of video bag of described counter, and adjust the not count value corresponding to video packets of transmission.

The embodiment of the present invention provides a kind of transmission equipment of video packets, comprising:

Determination module, for determining the priority of video packets, and the transmission delay of estimation video packets;

Counter distribution module, is used to video packets to distribute counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets;

Processing module, for according to the count value transmission of video bag of described counter, and adjusts the not count value corresponding to video packets of transmission.

As shown from the above technical solution, the embodiment of the present invention is by distributing counter for video packets, and count value is relevant with the priority of video packets and/or the transmission delay of video packets, can realize the preferential high video packets of priority that sends in the transmitting procedure of video packets, or preferential transmission is about to overtime video packets, thereby improve the quality of transmission of video.

Accompanying drawing explanation

Fig. 1 is the schematic flow sheet of transmission method one embodiment of video packets of the present invention;

Fig. 2 is the schematic flow sheet of another embodiment of transmission method of video packets of the present invention;

Fig. 3 is the schematic flow sheet of another embodiment of transmission method of video packets of the present invention;

Fig. 4 is the structural representation of transmission equipment one embodiment of video packets of the present invention;

Fig. 5 is the structural representation of another embodiment of transmission equipment of video packets of the present invention.

Embodiment

Fig. 1 is the schematic flow sheet of transmission method one embodiment of video packets of the present invention, comprising:

Step 11: determine the priority of video packets, and the transmission delay of estimation video packets;

Wherein, in transmission of video process, dissimilar video packets has different significance levels, for example, according to importance order from high to low, video packets can be divided into: I-frame video bag, P frame video packets and B frame video packets.Therefore, the priority that can preset I-frame video bag is the highest, is secondly P frame video packets, is finally B frame video packets.

Be understandable that, not distinguishing under the scene of I-frame video bag, P frame video packets and B frame video packets, also can adopt other dividing mode, and define corresponding priority for the video packets of every type.

The transmission delay of video packets can be according to the transmission delay of setting above the video packets of number of the character of the communication media of physical layer and current video bag, and estimation obtains, and the character of the communication media of physical layer is such as being propagation rate, propagation delay etc.

Step 12: for video packets is distributed counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets;

Wherein, this initial value can with priority and/or the transmission delay relation that is inversely proportional to, the priority of video packets transmission delay higher and/or estimation is larger, this initial value is just less.Or optional, the initial value of count value also can be proportional with priority and/or transmission delay, the priority of video packets transmission delay higher or estimation is larger, and this initial value is just larger.

Step 13: according to the count value transmission of video bag of described counter, and adjust the not count value corresponding to video packets of transmission.

For example, the relation if initial value and priority and/or transmission delay are inversely proportional to, so preferentially sends the video packets that count value is little, and after sending video packets, count value corresponding to video packets not sending is reduced to 1.Or, if initial value and priority and/or transmission delay are proportional, the so preferential large video packets of transmitting counter, and after sending video packets, the count value that the video packets not sending is corresponding increases by 1.

Optionally, before distributing counter for video packets, can first judge that whether video packets is overtime, for example, when the transmission delay of estimation is less than the delay requirement of setting, show not overtime, otherwise for overtime, when video packets is carried out the follow-up operations such as distribution counter after not overtime again.

In the present embodiment, because the priority of video packets is higher, show that video packets is more important, so just should preferentially send the video packets that priority is high; In addition, because the transmission delay of the video packets of estimating is larger, just show that this video packets approaches overtime, in order to meet the demand of low delay, this video packets just needs be transmitted the soonest so.In the present embodiment, according to priority and/or transmission delay, count value is set, and according to count value transmission of video bag, can guarantees the prioritised transmission of the video packets that priority is high or transmission delay is large, thereby improve video transmission quality.

Further, referring to Fig. 2, the present invention provides another kind of embodiment, and this embodiment can avoid the collision between video packets as far as possible.

As described in the background art, when the value of backoff counter is kept to 0, node just can send data.So, if there is the backoff counter of two or more nodes to reduce to 0 simultaneously, these nodes will send data simultaneously, and now channel will bump, and node cannot correctly receive data.Detect after collision, sending node starts retransmission processes, and this node increases the value of competition window, and reenters backoff procedure.If number of retransmissions surpasses the maximum of system regulation, abandon this bag, enter the process of transmitting of next packet.

In addition, the window value of different AC queues is different, specific as follows: W _min[AC_VO]=7, W _max[AC_VO]=15; W _min[AC_VI]=15, W _max[AC_VI]=31; W _min[AC_BE]=31, W _max[AC_BE]=1023; W _min[AC_BK]=31, W _max[AC_BK]=1023.

W due to AC_VO and AC_VI _minand W _maxbetween spacing less, for the video packets in AC_VO and these two queues of AC_VI, will more easily bump so.

In order to reduce collision probability, the present embodiment comprises:

Step 21: different video packets is assigned in different AC queues.

Wherein, video packets can be divided into according to importance: I-frame video bag, P frame video packets and B frame video packets, I-frame video bag is most important, is secondly P frame video packets, is finally B frame video packets.

So, I-frame video bag and P frame video packets can be assigned in the AC queue of higher priority, for example, be assigned in AC_VI queue; B frame video packets is assigned in the AC queue of lower priority, for example, is assigned in AC_BE queue.

Optionally, due in some agreements, video packets can not be divided into I-frame video bag, P frame video packets and B frame video packets, can distribute AC queue according to the priority of video packets so, for example, the video packets of higher priority is assigned in the AC queue of higher priority, the video packets of lower priority is assigned in the AC queue of lower priority.

Step 22: the video packets in the AC queue of setting is transmitted according to count value.

Wherein, the AC queue of setting can be the AC queue that priority is higher, for example, in above-mentioned steps, video packets is distributed to respectively to AC_VI queue and AC_BE queue, and the AC queue of setting so just refers to AC-VI queue.

Afterwards the video packets in this AC_VI queue is transmitted according to count value, idiographic flow can be referring to a upper embodiment.

In the present embodiment, according to priority and/or transmission delay, count value is set, and according to count value transmission of video bag, can guarantees the prioritised transmission of the video packets that priority is high or transmission delay is large, thereby improve video transmission quality.In addition, the present embodiment is by being assigned to different video packets in different AC queues, there are so a plurality of video user simultaneously during transmitting video data, can reduce the number of the video packets in the AC queue that is assigned to higher priority, and then can reduce the probability conflicting in network, improve network effective throughput.

Fig. 3 is the schematic flow sheet of another embodiment of transmission method of video packets of the present invention, and the present embodiment be take and video packets distributed to AC_VI and AC-BE queue is example, and the present embodiment comprises:

Step 31: for video packets arranges priority.

For example, represent the priority of video packets p with prio (p), the priority of video packets can be set to:

$\mathrm{prio}\left(p\right)=\left\{\begin{array}{cc}1,& I\\ 2,& P\\ 3,& B\end{array}\right.$

Above formula shows: the priority value of I-frame video bag is that the priority value of 1, P frame video packets is that the priority value of 2, B frame data bag is 3.

Afterwards, can in the packet header of video packets, carry the priority of video packets, for example, at network abstraction layer unit (the Network Abstract Layer Unit of video packets, NALU) in NRI (Nal_ref_dc) field of head, carry, occurrence can be expressed as:

$\mathrm{NRI}=\left\{\begin{array}{cc}00,& \mathrm{prio}\left(p\right)=3\\ 01,& \mathrm{prio}\left(p\right)=2\\ 10,& \mathrm{prio}\left(p\right)=1\end{array}\right.$

Above formula shows: the value of the NRI field of the video packets that priority value is 3 is 00, and the value of the NRI field of the video packets that priority value is 2 is 01, and the value of the NRI field of the video packets that priority value is 1 is 10.

Be understandable that, the value of the priority of above-mentioned setting and the value of NRI are a kind of example, also can adopt other modes that priority is set.

Step 32: according to the priority of video packets, video packets is assigned in corresponding queue.

For example, if prio (p)=3, the queue end of this video packets being inserted to AC_BE, otherwise the queue end of inserting AC_VI.

Be understandable that, the AC queue that the present embodiment distributes is a kind of example, also can be assigned in the AC queue of alternate manner.

According to the method for salary distribution of the present embodiment, I-frame video bag and P frame video packets will be assigned in AC_VI queue, and B frame data bag will be assigned in AC_BE queue.

Step 33: the transmission delay of video packets in estimation AC_VI queue.

Computing formula can be as follows: ${\hat{E}}_L=\frac{E_{L,\min }+E_{L,\max }}{2}$

Wherein,

$E_{L,\min }=(1+\stackrel{\‾}{R})(\mathrm{\α}+{\mathrm{\β}}_{\min }+{\stackrel{\‾}{T}}_{\mathrm{pause}}\×L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\δ})$

$E_{L,\max }=(1+\stackrel{\‾}{R})(\mathrm{\α}+{\mathrm{\β}}_{\max }+{\stackrel{\‾}{T}}_{\mathrm{pause}}\×L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\δ})$

$\mathrm{\α}=\underset{j=1}{\overset{L}{\mathrm{\Σ}}}{T}_{j,\mathrm{trans}},$

$T_{j,\mathrm{trans}}=\mathrm{AIFS}[\mathrm{AC}\_\mathrm{VI}]+\frac{S_{j,\mathrm{data}}+S_{\mathrm{header}}}{\mathrm{\υ}}+\mathrm{\δ}+\mathrm{SIFS}+\mathrm{\δ}$

${\mathrm{\β}}_{\min }=\frac{\mathrm{aSlotTime}\×W_{\min }[\mathrm{AC}\_\mathrm{VI}]\×L}{2}$

${\mathrm{\β}}_{\max }=\frac{\mathrm{aSlotTime}\×W_{\max }[\mathrm{AC}\_\mathrm{VI}]\×L}{2}$

${\stackrel{\‾}{T}}_{\mathrm{pause}}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{t}_{-k,\mathrm{pause}}$

$\stackrel{\‾}{R}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{r}_{-k}$

$T_{\mathrm{ACK}}=\frac{S_{\mathrm{ACK}}}{\mathrm{\υ}}$

Wherein, transmission delay for estimation; S _{j, data}it is the size of j bag in AC_VI queue; S _headerit is the size of MAC layer header; S _aCKit is the size of ACK bag; t _{-k, pause}be k the break period of wrapping in backoff procedure above of the video packets of current estimation, namely when listening to channel busy, backoff counter keeps the constant time of count value; r _-kk the bag number of retransmissions above of the video packets of current estimation; υ is the transmission rate of physical layer, δ is the propagation delay of physical layer, M is the number of wrapping above of the video packets of the current estimation of choosing set, AIFS[AC_VI]=2, aSlotTime is DCF system time constant, and the carrier detect of channel and data send all take this constant as basic time unit.T in above-mentioned parameter _{-k, pause}and r _-kcan obtain by the transmission situation of video packets above of statistics current video bag, all the other parameters are set point or agreement setting.

Step 34: after the video packets in AC_VI queue is not overtime, for video packets is distributed counter, and the initial value of count value is set.

Wherein, suppose that τ is the delay requirement of setting, when the transmission delay of estimation while being less than τ, showing not overtimely, otherwise is overtime.After video packets is overtime, can abandon this video packets.

The computing formula of the initial value arranging can be:

$c_0=\left\{\begin{array}{cc}0,& \mathrm{prio}\left(p\right)=2\\ \frac{2\&times;c_{\min }\&times;{\hat{E}}_L}{\mathrm{\&tau;}},& \mathrm{prio}\left(p\right)=\mathrm{land}{\hat{E}}_L<\frac{\mathrm{\&tau;}}{2}\\ c_{\min },& \mathrm{prio}\left(p\right)=\mathrm{land}{\hat{E}}_L\&GreaterEqual;\frac{\mathrm{\&tau;}}{2}\end{array}\right.$

And,

Wherein, τ is the delay requirement of setting;

F is frame per second;

it is the number that an average frame is divided into video packets;

N is the number of all frame of video in a picture group (Group ofPicture, GOP);

N _pit is the number of P frame in a GOP;

expression rounds up.

In above-mentioned parameter can obtain by statistics, all the other parameters are the value of agreement regulation or the value of setting.

Step 35: if the video packets of transmission AC_VI queue is selected the video packets transmission of count value c minimum.

Wherein, in avoidance mechanism, node is that the count value in backoff counter is kept at 0 o'clock and shows that competition is to the channel right to use.Due to W corresponding to different AC queues _minand W _max, so corresponding each AC queue can arrange a backoff counter, and the count value of the backoff counter which AC queue is corresponding is first kept to 0, just shows to transmit the video packets of this AC queue.

Step 36: after video packets transmission, the count value of the remaining video bag by AC_VI in queue subtracts one.

In addition, if the video packets of transmission AC_BE queue can be transmitted according to putting in order of video packets in AC_BE queue.

The present embodiment, by the video packets of different priorities being distributed to different AC queues, can reduce the probability conflicting in network, improves network effective throughput; By in AC_VI queue according to priority and transmission delay count value, and according to count value transmission of video bag, can guarantee the prioritised transmission of important video packets, for example, the video packets that prioritised transmission priority is high, or prioritised transmission more approaches the video packets of delay requirement, thereby improved the quality of transmission of video.

Fig. 4 is the structural representation of transmission equipment one embodiment of video packets of the present invention, and this equipment can be the equipment of carrying out said method, and this equipment comprises determination module 41, counter distribution module 42 and processing module 43; Determination module 41 is for determining the priority of video packets, and the transmission delay of estimation video packets; Counter distribution module 42 is used to video packets to distribute counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets; Processing module 43 is for according to the count value transmission of video bag of described counter, and adjusts the not count value corresponding to video packets of transmission.

Referring to Fig. 5, this equipment can also comprise: queue assignment module 44, for according to the priority of video packets, is assigned to the video packets of different priorities in different AC queues.

Optionally, described queue assignment module 44, specifically for the video packets with the first priority is assigned in AC_VI queue, is assigned to the video packets with the second priority in AC_BE queue, and wherein the first priority is higher than the second priority; Described determination module 41 is specifically for the video packets estimation transmission delay in AC_VI queue.

Optionally, described determination module 41 specifically for: according to the transmission situation of setting above the video packets of number of the character of physical layer transmission medium and the current video packets that will estimate, the transmission delay of estimation video packets.

Optionally, described processing module 43 specifically for:

The relation if the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are inversely proportional to, the little video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission subtracted to 1; Or,

If the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are proportional, the large video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission added to 1.

Optionally, the computing formula of the transmission delay of described determination module 41 estimation video packets is:

${\hat{E}}_L=\frac{E_{L,\min }+E_{L,\max }}{2},$

Wherein,

$E_{L,\min }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\min }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$E_{L,\max }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\max }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$\mathrm{\&alpha;}=\underset{j=1}{\overset{L}{\mathrm{\&Sigma;}}}{T}_{j,\mathrm{trans}},$

$T_{j,\mathrm{trans}}=\mathrm{AIFS}[\mathrm{AC}\_\mathrm{VI}]+\frac{S_{j,\mathrm{data}}+S_{\mathrm{header}}}{\mathrm{\&upsi;}}+\mathrm{\&delta;}+\mathrm{SIFS}+\mathrm{\&delta;},$

${\mathrm{\&beta;}}_{\min }=\frac{\mathrm{aSlotTime}\&times;W_{\min }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\mathrm{\&beta;}}_{\max }=\frac{\mathrm{aSlotTime}\&times;W_{\max }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{t}_{-k,\mathrm{pause}},$

$\stackrel{\&OverBar;}{R}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{r}_{-k},$

$T_{\mathrm{ACK}}=\frac{S_{\mathrm{ACK}}}{\mathrm{\&upsi;}},$

Wherein, transmission delay for estimation; S _{j, data}it is the size of j bag in AC_VI queue; S _headerit is the size of MAC layer header; S _aCKit is the size of ACK bag; t _{-k, pause}be k the break period of wrapping in backoff procedure above of the video packets of current estimation, namely when listening to channel busy, backoff counter keeps the constant time of count value; r _-kk the bag number of retransmissions above of the video packets of current estimation; υ is the transmission rate of physical layer; δ is the propagation delay of physical layer; M is the number of wrapping above of the video packets of the current estimation of choosing set; AIFS[AC_VI]=2, aSlotTime is DCF system time constant.

Optionally, described in there is the first priority video packets comprise that priority is the video packets that 1 video packets and priority are 2, the computing formula of the initial value of the counter of described module assigns is:

$c_0=\left\{\begin{array}{cc}0,& \mathrm{prio}\left(p\right)=2\\ \frac{2\&times;c_{\min }\&times;{\hat{E}}_L}{\mathrm{\&tau;}},& \mathrm{prio}\left(p\right)=\mathrm{land}{\hat{E}}_L<\frac{\mathrm{\&tau;}}{2}\\ c_{\min },& \mathrm{prio}\left(p\right)=\mathrm{land}{\hat{E}}_L\&GreaterEqual;\frac{\mathrm{\&tau;}}{2}\end{array}\right.$

And,

Wherein,

Prio (p) represents priority; τ is the delay requirement of setting; F is frame per second; it is the number that an average frame is divided into video packets; N is the number of all frame of video in a GOP; N _pit is the number of P frame in a GOP; expression rounds up.

In the present embodiment, according to priority and/or transmission delay, count value is set, and according to count value transmission of video bag, can guarantees the prioritised transmission of the video packets that priority is high or transmission delay is large, thereby improve video transmission quality.

One of ordinary skill in the art will appreciate that: all or part of step that realizes above-mentioned each embodiment of the method can complete by the relevant hardware of program command.Aforesaid program can be stored in a computer read/write memory medium.This program, when carrying out, is carried out the step that comprises above-mentioned each embodiment of the method; And aforesaid storage medium comprises: various media that can be program code stored such as ROM, RAM, magnetic disc or CDs.

Finally it should be noted that: each embodiment, only in order to technical scheme of the present invention to be described, is not intended to limit above; Although the present invention is had been described in detail with reference to aforementioned each embodiment, those of ordinary skill in the art is to be understood that: its technical scheme that still can record aforementioned each embodiment is modified, or some or all of technical characterictic is wherein equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution depart from the scope of various embodiments of the present invention technical scheme.

Claims (9)

1. a transmission method for video packets, is characterized in that, comprising:

Determine the priority of video packets, and the transmission delay of estimation video packets;

For video packets is distributed counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets;

According to the count value transmission of video bag of described counter, and adjust the not count value corresponding to video packets of transmission;

The transmission delay of described estimation video packets, comprising:

According to the transmission situation of the video packets of number of setting above of the character of physical layer transmission medium and the current video packets that will estimate, the transmission delay of estimation video packets;

The computing formula of the transmission delay of described estimation video packets is:

${\hat{E}}_L=\frac{E_{L,\min }+E_{L,\max }}{2},$

Wherein,

$E_{L,\min }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\min }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$E_{L,\max }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\max }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$\mathrm{\&alpha;}=\underset{j=1}{\overset{L}{\mathrm{\&Sigma;}}}{T}_{j,\mathrm{trans}},$

$T_{j,\mathrm{trans}}=\mathrm{AIFS}[\mathrm{AC}\_\mathrm{VI}]+\frac{S_{j,\mathrm{data}}+S_{\mathrm{header}}}{\mathrm{\&upsi;}}+\mathrm{\&delta;}+\mathrm{SIFS}+\mathrm{\&delta;},$

${\mathrm{\&beta;}}_{\min }=\frac{\mathrm{aSlotTime}\&times;W_{\min }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\mathrm{\&beta;}}_{\max }=\frac{\mathrm{aSlotTime}\&times;W_{\max }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{t}_{-k,\mathrm{pause}},$

$\stackrel{\&OverBar;}{R}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{r}_{-k},$

$T_{\mathrm{ACK}}=\frac{S_{\mathrm{ACK}}}{\mathrm{\&upsi;}},$

Wherein, transmission delay for estimation; S _{j, data}it is the size of j bag in AC_VI queue; S _headerit is the size of MAC layer header; S _aCKit is the size of ACK bag; t _{-k, pause}be k the break period of wrapping in backoff procedure above of the video packets of current estimation, namely when listening to channel busy, backoff counter keeps the constant time of count value; r _-kk the bag number of retransmissions above of the video packets of current estimation; υ is the transmission rate of physical layer; δ is the propagation delay of physical layer; M is the number of wrapping above of the video packets of the current estimation of choosing set; AIFS[AC_VI]=2, aSlotTime is DCF system time constant, W _min[AC_VI] is the min-window value of AC_VI queue, W _max[AC_VI] is the max-window value of AC_VI queue, and L is a set point.

2. method according to claim 1, is characterized in that, also comprises:

Different video packets is assigned in different access style AC queues;

The transmission delay of described estimation video packets, comprising: to the video packets estimation transmission delay in the AC queue of setting.

3. method according to claim 2, is characterized in that,

Described different video packets is assigned in different AC queues, comprises: the video packets with the first priority is assigned in AC_VI queue, the video packets with the second priority is assigned in AC_BE queue, wherein the first priority is higher than the second priority;

Described to the video packets estimation transmission delay in the AC queue of setting, comprising: to the video packets estimation transmission delay in AC_VI queue.

4. according to the method described in claim 1-3 any one, it is characterized in that, described according to the count value transmission of video bag of described counter, and adjust the not count value corresponding to video packets of transmission, comprising:

The relation if the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are inversely proportional to, the little video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission subtracted to 1; Or,

If the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are proportional, the large video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission added to 1.

5. method according to claim 3, is characterized in that, described in there is the first priority video packets comprise that priority is the video packets that 1 video packets and priority are 2, the computing formula of the initial value of described counter is:

$c_0=\left\{\begin{array}{cc}0,& \mathrm{prio}\left(p\right)=2\\ \frac{2\&times;c_{\min }\&times;{\hat{E}}_L}{\mathrm{\&tau;}},& \begin{array}{ccc}\mathrm{prio}\left(p\right)=1& \mathrm{and}& {\hat{E}}_L<\frac{\mathrm{\&tau;}}{2}\end{array}\\ c_{\min },& \begin{array}{ccc}\mathrm{prio}\left(p\right)=1& \mathrm{and}& {\hat{E}}_L\&GreaterEqual;\frac{\mathrm{\&tau;}}{2}\end{array}\end{array}\right.$

And,

Wherein,

Prio (p) represents priority;

τ is the delay requirement of setting;

F is frame per second;

it is the number that an average frame is divided into video packets;

N is the number of all frame of video in a GOP;

N _pit is the number of P frame in a GOP;

expression rounds up.

6. a transmission equipment for video packets, is characterized in that, comprising:

Determination module, for determining the priority of video packets, and the transmission delay of estimation video packets;

Counter distribution module, is used to video packets to distribute counter, and the initial value of described counter is to determine according to the transmission delay of the priority of described video packets and/or described video packets;

Processing module, for according to the count value transmission of video bag of described counter, and adjusts the not count value corresponding to video packets of transmission;

Described determination module specifically for: according to the transmission situation of setting above the video packets of number of the character of physical layer transmission medium and the current video packets that will estimate, the transmission delay of estimation video packets;

The computing formula of the transmission delay of described estimation video packets is:

${\hat{E}}_L=\frac{E_{L,\min }+E_{L,\max }}{2},$

Wherein,

$E_{L,\min }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\min }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$E_{L,\max }=(1+\stackrel{\&OverBar;}{R})(\mathrm{\&alpha;}+{\mathrm{\&beta;}}_{\max }+{\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}\&times;L)-(T_{\mathrm{ACK}}+\mathrm{SIFS}+\mathrm{\&delta;}),$

$\mathrm{\&alpha;}=\underset{j=1}{\overset{L}{\mathrm{\&Sigma;}}}{T}_{j,\mathrm{trans}},$

$T_{j,\mathrm{trans}}=\mathrm{AIFS}[\mathrm{AC}\_\mathrm{VI}]+\frac{S_{j,\mathrm{data}}+S_{\mathrm{header}}}{\mathrm{\&upsi;}}+\mathrm{\&delta;}+\mathrm{SIFS}+\mathrm{\&delta;},$

${\mathrm{\&beta;}}_{\min }=\frac{\mathrm{aSlotTime}\&times;W_{\min }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\mathrm{\&beta;}}_{\max }=\frac{\mathrm{aSlotTime}\&times;W_{\max }[\mathrm{AC}\_\mathrm{VI}]\&times;L}{2},$

${\stackrel{\&OverBar;}{T}}_{\mathrm{pause}}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{t}_{-k,\mathrm{pause}},$

$\stackrel{\&OverBar;}{R}=\frac{1}{M}\underset{k=1}{\overset{M}{\mathrm{\&Sigma;}}}{r}_{-k},$

$T_{\mathrm{ACK}}=\frac{S_{\mathrm{ACK}}}{\mathrm{\&upsi;}},$

Wherein, transmission delay for estimation; S _{j, data}it is the size of j bag in AC_VI queue; S _headerit is the size of MAC layer header; S _aCKit is the size of ACK bag; t _{-k, pause}be k the break period of wrapping in backoff procedure above of the video packets of current estimation, namely when listening to channel busy, backoff counter keeps the constant time of count value; r _-kk the bag number of retransmissions above of the video packets of current estimation; υ is the transmission rate of physical layer; δ is the propagation delay of physical layer; M is the number of wrapping above of the video packets of the current estimation of choosing set; AIFS[AC_VI]=2, aSlotTime is DCF system time constant, W _min[AC_VI] is the min-window value of AC_VI queue, W _max[AC_VI] is the max-window value of AC_VI queue, and L is a set point.

7. equipment according to claim 6, is characterized in that, also comprises:

Queue assignment module, for according to the priority of video packets, is assigned to the video packets of different priorities in different access style AC queues.

8. equipment according to claim 7, is characterized in that,

Described queue assignment module, specifically for the video packets with the first priority is assigned in AC_VI queue, is assigned to the video packets with the second priority in AC_BE queue, and wherein the first priority is higher than the second priority;

Described determination module is specifically for the video packets estimation transmission delay in AC_VI queue.

9. according to the equipment described in claim 6-8 any one, it is characterized in that, described processing module specifically for:

The relation if the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are inversely proportional to, the little video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission subtracted to 1; Or,

If the priority of the initial value of described counter and described video packets and/or the transmission delay of described video packets are proportional, the large video packets of prioritised transmission count value, and the count value corresponding to video packets of not transmission added to 1.