Self-adaptive service quality ensuring method in the multicast environment
Technical field
The present invention relates to the procotol communication technical field, particularly relate to the Adaptive QoS (Quality-of-Service in a kind of multicast environment, service quality) ensuring method, especially a kind ofly initiate mechanism and the recipient initiates the Adaptive QoS ensuring method that mechanism combines by transmit leg, the recipient initiates mechanism in the video quality of adjusting the recipient in real time according to network condition and being received, start transmit leg in due course and initiate mechanism, consult dynamically to adjust overall video quality by transmit leg utilization sampling, not only can control and optimize video quality and network utilization on the whole, the part that influenced by network congestion in the multicast group can also be isolated, for different user provides different video qualities.
Background technology
Traditional IP (Internet Protocol) communication has dual mode: first kind is to carry out i.e. clean culture (unicast) between a source IP main frame and a purpose IP main frame; Second kind is to carry out between all other the IP main frame in a source IP main frame and network, i.e. broadcasting (broadcast).And ip multicast (multicast), certain that also claims multicast to be meant in IP network packet is sent in the network with the form of do one's best (best-effort) is determined the node subclass, this subclass is called multicast group (multicast group).The basic thought of ip multicast is, source host only sends a piece of data, and the destination address in this piece of data is the multicast group address; All recipients in the multicast group can receive same data copy, and have only the main frame (destination host) in the multicast group can receive these data, and other main frame can not be received in the network.And IP QoS is meant the service quality of IP, just refers to the performance when IP traffic passes through network.It has a cover tolerance index, comprises service availability, delay, variable delay, throughput and packet loss or the like.
QoS in the multicast environment guarantees that mechanism can be divided into two classes substantially: a class is to utilize resource reservation to come guaranteed qos, also can be called the hard assurance of QoS.Its core is that the user submits request to, is given security by network, mainly finishes by resource reservation.The advantage of this method is that QoS assurance end to end can be provided on IP network.But the requirement to router is very high, and when the data traffic in the network was very big, the storage of router and disposal ability can run into very big pressure.Therefore extensibility is very poor, is difficult to implement at core network.In addition, RSVP can't reserved resource also and be not equal to and do not have enough resources on the network, and reserved resource also might not all can be used by this user constantly, so it is not high to introduce the resource utilization of network of resource reservation, and can't be according to the change dynamics adjustment of network environment to obtain the service quality of the appreciable the best of user.Therefore, Adaptive QoS also can be called the soft assurance of QoS, more and more comes into one's own.The core of Adaptive QoS is that the user dynamically adjusts demand parameter, adapts to current network condition, so that under current network condition, obtains the service quality of the appreciable the best of user.This method be fine-grained, can reflect user's individual demand better, mainly act on terminal.
Adaptive QoS assurance mechanism in the present existing multicast environment mainly contains two kinds: transmit leg is initiated mechanism (sender-initiated schemes) and the recipient initiates mechanism (receiver-initiated schemes).
It is to be responsible for the congestion situation of monitoring network and to be taked corresponding reclamation activities by transmit leg that transmit leg is initiated mechanism.Wherein to the monitoring of network congestion, mainly be that periodically the packet loss sent of statistics and analysis recipient or the data report of time delay are finished by transmit leg.When the not good recipient's of reception condition quantity surpassed the ratio that is allowed in the multi-casting communication of setting in advance, the sender will reduce the quality and the speed of whole video transmission.Its advantage is to realize simply also not needing to rely on special coding techniques.Its major defect is to be not suitable for isomery multicast environment, that is to say, as long as some recipient has run into bigger packet loss in the multicast group, all recipients will be forced to accept the reduction of video quality in the then multicast group.Therefore can only satisfy single transmission rate request, the recipient can not satisfy simultaneously to the different requirements of bandwidth.And traditional transmit leg initiates mechanism and requires all recipients that feedback information all is provided in real time, so that analyze and adjust the transmission rate of transmit leg in real time.Thereby should the mechanism autgmentability poor, under the situation of recipient's One's name is legion, be easy to produce feedback implosion.
It is to be responsible for the congestion situation of monitoring network and the quality of reception of adjustment oneself by the recipient that the recipient initiates mechanism.Such as layered multicast, the most frequently used exactly recipient initiates mechanism.Its basic thought is to encode video into the basic layer bit stream that can decode separately and one or more enhancement layer bitstream that can block in any place, wherein basic layer bit stream adapts to the minimum network bandwidth, and enhancement layer bitstream is used for the dynamic range of overlay network bandwidth change.Every layer all is assigned with a different multicast address, thereby makes video flowing transmission in several different multicasts connect of layering.Each recipient adds multicast group as much as possible according to s own situation and network condition, receives enhancement layer bitstream as much as possible, thereby obtains better video quality.Compare with transmit leg initiation mechanism, the main advantage that the recipient initiates mechanism is that it can will be isolated by the part of network congestion in the multicast group, makes this part selection to video quality not influence other members of multicast group.Yet this mechanism also has the shortcoming of self.At first, this mechanism is to the coding requirement height, and each recipient tends to influence each other to the adjusting of the quality of reception, is difficult to coordinate.In the layered multicast mode, the adjusting fineness ratio of hierarchical coding is thicker, generally can only support few in number which floor, because layering too much can increase coding difficulty and control information amount, also can consume the state table on a large amount of routers.In addition, dynamically add or withdraw from the multicast group and also can increase expense.And because each layer bit stream is all propagated on a diverse multicast tree, these multicast trees even may not share identical bottleneck link in this case, are removed a layer bit stream and perhaps can not be solved congested.In addition, if network congestion just occurs near the sender the link in fact, though most recipient does not receive high level data, the sender still can encode and sends with the highest picture quality.This is to the system resource of transmit leg, with and near the network bandwidth, all be great waste.
Summary of the invention
An object of the present invention is to provide and initiate mechanism and the recipient initiates the Adaptive QoS ensuring method that mechanism combines by transmit leg in a kind of multicast environment, its recipient initiates mechanism in the video quality of adjusting the recipient in real time according to network condition and being received, start transmit leg in due course and initiate mechanism, consult dynamically to adjust overall video quality by transmit leg utilization sampling, thereby not only can control and optimize video quality and network utilization on the whole, the part that influenced by network congestion in the multicast group can also be isolated, for different user provides different video qualities.Also can utilize key-course in due course, send an application of regulating the QoS grade, start transmit leg and initiate mechanism to transmit leg.
Another object of the present invention provides the Adaptive QoS ensuring method in a kind of multicast environment, transmit leg utilization sampling consults dynamically to adjust overall video quality, when controlling on the whole and optimizing video quality and network utilization, avoided feedback implosion.
Another object of the present invention provides the Adaptive QoS ensuring method in a kind of multicast environment, transmit leg is in the process that sampling is consulted, can carry out state-detection to the recipient who does not return feedback information, to confirm whether this recipient is in state of activation, thereby real-time update group membership's information and state recording are so that effectively manage and charge.
Another object of the present invention provides the Adaptive QoS ensuring method in a kind of multicast environment, do not need by intermediate node and router, adjust demand parameter by terminal, adapt to current network condition, so that under the current network condition, make each recipient all can obtain satisfied video quality.
Another object of the present invention provides the Adaptive QoS ensuring method in a kind of multicast environment, initiating mechanism by the transmit leg initiation is machine-processed and recipient combines, the scope that QoS is regulated is wideer, and the adjusting granularity is thinner, can satisfy how different user's needs simultaneously.
Technical scheme
Transmit leg is initiated mechanism and recipient initiates mechanism and combines, both had the advantage that transmit leg is initiated mechanism, has the advantage that the recipient initiates mechanism again, not only can control and optimize service quality and network utilization on the whole, the part that influenced by network congestion in the multicast group can also be isolated, make this part selection not influence other members of multicast group, for different user provides different service quality to service quality.
Description of drawings
Fig. 1 is the network diagram of the Adaptive QoS ensuring method in the multicast environment of the present invention.
Fig. 2 is recipient's process chart of the Adaptive QoS ensuring method in the multicast environment of the present invention.
Fig. 3 is the transmit leg process chart of the Adaptive QoS ensuring method in the multicast environment of the present invention.
Embodiment
At this, proposed to initiate mechanism and the recipient initiates the Adaptive QoS ensuring method that mechanism combines by transmit leg in a kind of multicast environment.
Fig. 1 has provided the network diagram of this Adaptive QoS ensuring method.As we can see from the figure, transmit leg has only one, and is a plurality of but the recipient has.On each recipient, all recipient's handling procedure to be moved, and on transmit leg, the transmit leg handling procedure will be moved.
Recipient's handling process is mainly finished the function that the recipient initiates mechanism as shown in Figure 2, and starts transmit leg initiation mechanism in due course.Concrete steps are as follows:
S1: the deterioration/improvement of network is monitored and judged to parameters such as the packet loss of recipient by real-time statistics and analysis Real-time Transport Protocol (Real-time TransportProtocol, RTP), delay.
S2: the recipient regulates the video quality that receives voluntarily according to the monitoring result among the S1.The video quality that reduces recipient's reception under the situation of network impairment adapts to the variation of network, is exactly the multicast group that withdraws from one or more enhancement layer bitstreams in layered multicast; Under the situation that network takes a turn for the better, improve the video quality that the recipient receives, in layered multicast the multicast group that adds one or more enhancement layer bitstreams.
Only adopting the recipient to initiate under the situation of mechanism, if network congestion just occurs near the link of sender in fact, though most of recipients have reduced the quality of reception, but the sender still can encode and sends with the highest picture quality, has caused system resource and waste of network resources.In fact in this case, the sender should suitably reduce image compression quality, as selecting occupied bandwidth image compression algorithm still less, reduces image resolution ratio etc., or reduce transmission rate and carry out integrally-regulatedly, rather than simply allow single recipient carry out the adjusting of picture quality from row.Address this problem, just need to introduce transmit leg and initiate mechanism.
Traditional transmit leg is initiated mechanism and is required all recipients that feedback information all is provided in real time, so that the transmission rate of real-time analysis and adjustment transmit leg.This implementation autgmentability is poor, under the situation of recipient's One's name is legion, is easy to produce feedback implosion.Especially under the situation of network congestion, a large amount of feedback informations is further blocking network not only, also may be because losing of feedback information causes the result of voting in the multicast group to lose efficacy.Such as all finding network congestion most recipients, when wishing that the sender reduces whole transmission rate, these recipients can send the application that reduces QoS to the sender.But because near the network these recipients has taken place congested, a large amount of applications that they send are lost possibly, the degradation application that causes the sender to receive does not reach the passing ratio of voting, thereby refuses the video quality and the transmission rate of integral body are adjusted.At this situation, in the Adaptive QoS ensuring method in the multicast environment that the present invention proposes, the recipient is under the situation that monitors network impairment/improvement, except adjusting the video quality that oneself receives voluntarily, also can send the adjusting application of a reduction/raising QoS grade to transmit leg, start transmit leg and initiate mechanism.Transmit leg is initiated mechanism and is then utilized the sampling negotiation method dynamically to adjust the utilance of overall video quality, optimization network.Specific practice is, will apply for that all the sender just can know recipient's sum like this to the sender before at first requiring each recipient to add the multicast Video Applications, also knows each recipient's unicast address.Need set up a key-course in addition, just be exclusively used in the multicast group of control information, all recipients must add this multicast group.The recipient withdraws from and also should notify transmit leg before multicast is used, and makes data and recipient's list information of the scale that it can the relevant multicast group of real-time update.Regulate application and adopt the inhibition transmit mechanism.Concrete steps are as follows:
S3: the recipient starts one and sends the delay timer of regulating application, and it is set to the random value in the certain limit.
S4: if before timer expiry, this recipient has received the adjusting application that other recipient sends, and then cancels the timer of oneself and regulates application, has so just suppressed to regulate the transmission that repeats of application.
S5: timer expiry, then this recipient will regulate application by key-course and send to transmit leg and all recipients with the multicast form.
S6: jump to the S1 circulation and carry out.
The handling process of transmit leg is mainly finished the function that transmit leg is initiated mechanism as shown in Figure 3.Concrete steps are as follows:
S1: the adjusting application message that transmit leg is sent in key-course monitoring reception side;
S2: after receiving the adjusting application, transmit leg adopts the sampling negotiation method, a part of object as the sampling inquiry of picked at random from recipient's tabulation.Sampling proportion is decided on the scale of multicast group.
S3: the target sample that sending direction is chosen sends message, inquires its video reception situation.Sampling is inquired and is replied and all adopt the clean culture form to carry out.Because the inquiry sample is a picked at random, so can characterize recipient's integral status.
S4: transmit leg is analyzed according to the recipient's who is selected feedback information, adjusts the total quality and the transmission rate of video in real time.Thereby when controlling on the whole and optimizing video quality and network utilization, avoided feedback implosion.In the process that each sampling is consulted with and subsequent certain hour in, transmit leg will abandon other that receive during this period and regulate application, to avoid regulating the reprocessing of application and the fluctuation of service quality.The random sampling negotiation method can reduce feedback information volume greatly, thereby has reduced the taking of Internet resources, and has effectively avoided feedback implosion.
The recipient should notify transmit leg before withdrawing from the multicast Video Applications, makes data and recipient's list information of the scale that it can the relevant multicast group of real-time update.But some recipients might be improper withdrawing from.In this case, transmit leg can't obtain it and withdraw from message, and this management and charging of using to multicast has caused very big difficulty.In order to address this problem, transmit leg does not return any feedback information if find certain recipient who is pumped in the process that random sampling is consulted, then can start the node state detection module, whether is in state of activation to confirm this recipient.Thereby real-time update group membership's information and state recording are so that effectively manage and charge.If the node state detection module is repeatedly inquired this recipient and is not all received response, this recipient will be removed from recipient's tabulation, upgrade various management information simultaneously.
S5: jump to the S1 circulation and carry out.
Adaptive QoS ensuring method in the multicast environment that we propose goes for various multimedia application, for it provides real-time detection, controlling mechanism, makes it possess the feature of Adaptive QoS.Do not need by intermediate node and router, adjust demand parameter, adapt to current network condition,, obtain best service quality so that under current network condition by terminal.Transmit leg is initiated mechanism and recipient initiate mechanism and combine, not only can control and optimize video quality and network utilization on the whole, the part that influenced by network congestion in the multicast group can also be isolated, for different user provides different video qualities.Has the advantage that the recipient initiates mechanism, the part that influenced by network congestion in the multicast group can be isolated, make this part selection not influence other members of multicast group to video quality, simultaneously can be according to each recipient's actual conditions and individual demand, for different user provides different video qualities.The recipient except adjusting the video quality that oneself receives voluntarily, also can utilize key-course under the situation that monitors network impairment/improvement, to the adjusting application of a reduction/raising QoS grade of transmit leg transmission, start transmit leg and initiate mechanism.Regulate application and adopted the inhibition transmit mechanism, to avoid regulating the transmission that repeats of application.Transmit leg receives that regulating the application back utilizes sampling to consult dynamically to adjust overall video quality, control on the whole and optimize video quality and network utilization, not only avoided feedback implosion, also simultaneously craft personal information and state recording are so that effectively manage and charge.In addition, by two kinds of mechanism are combined, the scope that QoS is regulated is wideer, and the adjusting granularity is thinner, thereby is more suitable for isomery multicast environment.