Summary of the invention
In the isomery complete IP network, realize the quick switching problem of video stream traffic, the present invention proposes a kind of triggering method based on the quick handover mechanism of mobile IP v 6 (FMIPv6), specific implementation the link layer triggers signaling of IEEE 802.21 definition, reduce handover delay, guaranteed professional real-time.
The present invention proposes a kind of triggering method, comprise step based on the quick handover mechanism of mobile IP v 6:
(1) mobile node of transmitting video-frequency flow detects the received signal intensity (RSS) of current service network signal, when described detected received signal intensity is lower than predetermined thresholding, mobile node triggers the address assignment of FMIPv6, and wherein this thresholding is definite relevant with factors such as network transmitting power, communication environments, FMIPv6 signaling propagation delay times;
(2) mobile node frequently detects the received signal intensity of current service network, judges the mutual alignment relation between itself and the base station;
(3) judge it when the edge of current service network moves at mobile node, mobile node triggers quick Binding Update and the tunnel of FMIPv6 and sets up signaling procedure;
(4) when receiving the Binding Update affirmation, mobile node detects anti-shake buffer memory, and when the data volume in buffer memory met the demands, mobile node switched to another network.
Preferably, step (1) also comprises step:
When described detected received signal intensity was lower than predetermined thresholding, the link layer of mobile node sent Link_Quality_Cross_Threshold (quality of connection surmounts thresholding) signal to its network layer, triggered the address assignment of FMIPv6.
Preferably, step (2) also comprises step:
The mobile node link layer frequently detects the received signal intensity of current service network, by the detected value average of calculating and obtaining more at every turn, judges the mutual alignment relation between itself and the base station.
Preferably, step (3) also comprises step:
Judge it when the edge of current service network moves at mobile node, then the mobile node link layer sends Link_going_down (quality of connection is gradually bad) signal to network layer, triggers quick Binding Update of FMIPv6 and tunnel and sets up signaling procedure.
Preferably, step (4) also comprises step:
Detect data volume in the buffer memory when not enough at mobile node, continue to detect anti-shake buffer memory,, receive Link_down (connect and disconnect) signal, show that link layer connects to disconnect, then switch to another network from link layer if in the wait process.
Preferably described current service network is a wlan network, and described another network is a 3G network.
Preferably, step (1) also comprises step:
Can insert at the wlan network adjacent with described current service network, and when the received signal intensity of described adjacent wlan network surpasses predetermined thresholding, the link layer of mobile node sends Better_Signal_Quality_AP_Available (access point with better signal quality can be used) to its network layer, shows the wlan network that existence can insert;
If the mobile node network layer never receives the Better_Signal_Quality_AP_Available signal, show that adjacent area does not have the wlan network that can insert.
Preferably, step (1) also comprises step:
Current service network at mobile node is a wlan network, and when not having the adjacent wlan network that inserts, whether be lower than predetermined thresholding by the received signal intensity that detects current wlan network, decision sends former WLAN Link_Quality_Cross_Threshold, switches address assignment with the trigger network layer;
When having the adjacent wlan network that can insert, whether be higher than predetermined thresholding by the received signal intensity that detects adjacent wlan network, decision sends new WLANLink_Quality_Cross_Threshold, switches address assignment with the trigger network layer.
Preferably, after mobile node sends Link_Quality_Cross_Threshold, more frequently detect current network RSS, assay intervals is shortened to assay intervals before triggering
M gets 3~5.
Preferably, also comprise step:
When mobile node receives first received signal intensity level of current service network, described value is buffered in the buffer;
When mobile node receives second received signal intensity level of current service network, obtain the average of first and second received signal intensity level, so with buffer memory in first received signal intensity level relatively;
After receiving k received signal intensity level, obtain average with the average of preceding k-1 received signal intensity level, and the average of k-1 received signal intensity level relatively before in the average of described k received signal intensity level and the buffer memory, output is noted the result of each comparison, can draw the mutual alignment relation of mobile node and base station.
Preferably, when the received signal intensity level of receiving n ascendant trend continuously, show that mobile node moves to the direction near the base station, do not need to switch to other networks or subnet this moment, keeps original connection;
When the received signal intensity level of receiving n downward trend continuously, show that mobile node moves to the direction away from the base station, in the moment on the horizon, mobile node need switch to other networks or subnet, and sends Link_going_down and trigger the received signal intensity level;
After receiving continuously less than n received signal intensity level that descends, begin to receive rising received signal intensity level, perhaps the received signal intensity level is constant substantially, shows that then mobile node does not temporarily need the trigger network layer to switch;
Wherein the value of n can be according to the speed decision of mobile node, and the speed of mobile node is big more, and value is more little, and the speed of mobile node is more little, and value is big more.
Preferably, in step (4), mobile node detects anti-shake buffer memory and carries out according to following formula:
B_full=max{T_delay,T_accept}
Wherein, anti-shake data cached reproduction time is during greater than the B_full value, data volume in the expression buffer memory meets the demands, T_delay represents the link layer handover delay, promptly be connected to the time that connects with new network from mobile node and the disconnection of current service network, T_accept represents the time delay that business can be tolerated.
Preferably, the data volume in detecting buffer memory meets the demands, and mobile node repeatedly triggers when switching, and sends the Link_down signal at once, forces link layer to switch in advance and takes place;
When the data volume in detecting buffer memory can not meet the demands, detect buffer memory once more after waiting for certain hour,, then carry out link layer and switch if network layer is received Link_down signal from link layer during this period.
According to basic design of the present invention,, and belong to the class real-time service because video stream traffic needs big bandwidth, according to this business features, require video stream traffic to utilize express network as much as possible, as complete when overlapping when wlan network and cellular network, selection is linked into wlan network.Method of the present invention may further comprise the steps:
The mobile node (MN) that is linked into wlan network detects network signal---received signal intensity (RSS), if find new inserted wlan network, triggers Better_Signal_Quality_AP_Available; If no, then continue to detect.
When the RSS signal of current service network was lower than specific thresholding, the mobile node link layer was to its upper strata---and network layer sends the Link_Quality_Cross_Threshold signal, triggers FMIPv6 address assignment (being finished by signaling RtSolPr and PrRtAdv).
After Link_Quality_Cross_Threshold triggered, the mobile node link layer frequently detected network RSS, by the detected value average of calculating and obtaining more at every turn, judged the mutual alignment relation between mobile node and the base station.
If judge that mobile node moves to the WLAN coverage edge, then the mobile node link layer sends the Link_going_down signal to the upper strata, triggers quick Binding Update of FMIPv6 (FBU) and tunnel and sets up signaling procedure (HI and HAck).
When receiving Binding Update affirmation (FBack), mobile node detects anti-shake buffer memory, if data volume meets the demands in the buffer memory, then the compulsion links layer switches generation at once.
If data volume deficiency in the buffer memory then continues to detect anti-shake buffer memory, if in the wait process, receive Link_down signal from link layer, show that the link layer connection disconnects, and switches and takes place.
Embodiment
Describe video stream traffic FMIPv6 handoff procedure between WLAN and 3G network in complete IP network in detail below in conjunction with Fig. 1.All link layer triggers among the present invention all belong to local and trigger, and promptly send triggering signal by link-local course local network layer.
Video stream traffic is preferentially selected the broadband high-speed Network Transmission, in Fig. 1, be wlan network, but wlan network limited coverage area, shift out the wlan network that is connected when mobile node, and when not having to supply other wlan networks of access, need switch to the network that covers a wide range to keep communication continuity, Fig. 1 is an example with the 3G network, thinks that Wide Area Network can insert everywhere.
Concrete steps are as follows:
The every 300ms of mobile node link layer detects a link layer information.As: the WLAN network interface card detects the RSS of current and adjacent wlan network, and the 3G network interface card detects the RSS of 3G network.
Mobile node does not detect the signal of adjacent wlan network among the figure, and the RSS of current wlan network is lower than specific thresholding, network layer is not being received under the situation that Better_Signal_Quality_AP_Available triggers, directly receive the Link_Quality_Cross_Threshold of former WLAN, show that mobile node may be in network edge or the more weak zone of signal, and do not have switchable other wlan network, might need to switch in the 3G network.
After the mobile node network layer receives that Link_Quality_Cross_Threshold triggers, to current WLAN access point interconnected router request broker message (RtSolPr) and agent router notice message (PrRtAdv) with address acquisition information.
After link layer sends Link_Quality_Cross_Threshold simultaneously, think that the possibility of switching increases, need the frequent network change that detects, every 100ms detects a link layer information.When testing result satisfies the Link_going_down decision algorithm, send Link_going_down to network layer and trigger.Show that further mobile node will switch.
After network layer receives that Link_going_down triggers, send quick binding update messages, the mutual switching initiates and acknowledge message (HI and Hack) for current wlan network access point and 3G network access point (NodeB), set up the tunnel of the two, and send quick binding acknowledgement message (FBack) to mobile node.
After mobile node is received binding acknowledgement message, detect anti-shake data in buffer amount.The full degree of the sky of anti-shake buffer memory is defined as follows:
B_full=max{T_delay,T_accept}
Wherein, anti-shake data cached reproduction time is during greater than the B_full value, expression " expiring ", T_delay represents the link layer handover delay, and promptly mobile node disconnects with former network and being connected, to the time span that connects with new network, T_accept represents the time delay that business can be tolerated, for example speech business is generally 50ms, and video stream traffic is 250ms, and the interactive video business is 150ms etc.
If detecting anti-shake buffer memory " expires ", and owing to there is aforesaid repeatedly triggering, can think that the probability that switches generation is very big, then send the Link_down signal at once, forcing link layer to switch in advance takes place, in this case, according to definition above, then can not produce the time delay of user's perception; After detect the buffer memory sky, then waiting for certain hour, detect buffer memory once more,, show that link layer switches the beginning of having to, then may produce time delay this moment if network layer is received Link_down signal from link layer during this period.
Link layer switch finish after, Link_up signal indicating network layer this moment can be used link layer communications, mobile node sends quick neighbor advertisement message (FNA) to new access point, communicates with new network.
Fig. 2 is a mobile node end FMIPv6 handover trigger judging process.As shown in the figure, judge and switch to which kind of network by whether receiving the Better_Signal_Quality_AP_Available signal.If switch to 3G network, then when the RSS of former WLAN is lower than thresholding, trigger the address and prepare; If switch to new wlan network, then when the RSS of new WLAN is higher than certain threshold, trigger the address and prepare.And, the link layer handover delay difference of heterogeneous networks, therefore the judgement standard difference of anti-shake buffer memory.
The decision algorithm of Link_going_down signal is described in conjunction with Fig. 3.According to the definition of IEEE802.21, comprise two types triggering signal: event mode and forecasting type.Link_going_down belongs to the forecasting type signal, need provide confidence level and trigger parameter effective time.Mobile node is by measure R SS variation tendency, and the direction of motion of judgement mobile node is further judged and switched the possibility that takes place.Because the existence of decline, only therefore the individual signals judgment signal variation tendency by receiving need be judged by the average of a plurality of signals.Decision mechanism as shown in Figure 3, concrete steps are as follows:
After mobile node sent Link_Quality_Cross_Threshold, every 100ms detected a current network RSS, when receiving first signal, this value was buffered in the buffer among Fig. 3;
After detecting second signal, obtain the average of first and second signal, and then compare with first signal;
After receiving k signal, obtain average with the average of a preceding k-1 signal, and the average of the average of this k signal and a preceding k-1 signal is relatively, output is noted the result of each comparison, can draw variation tendency.
In order to reduce the measurement shake, when defining the signal that n variation tendency of reception is identical continuously, the variation tendency of ability decision network signal.
When the signal of receiving n ascendant trend continuously, think that mobile node moves to the direction near access point, do not need to switch to other networks or subnet this moment, therefore keep original connection;
When the signal of receiving n downward trend continuously, think that mobile node moves to the direction of principle access point, in the moment on the horizon, mobile node may need to switch to other networks or subnet, therefore can send the Link_going_down triggering signal;
Under other situations, for example: receive continuously less than behind n the signal that descends, begin to receive rising signals, perhaps signal is constant substantially, and it is smaller to think that then mobile node shifts out the possibility of network, does not temporarily need the trigger network layer to switch.
The value of n can be according to the speed decision of mobile node.Speed is big more, and value is more little, and speed is more little, and value is big more, triggers too early when avoiding the low speed situation.
Table 1 provides and relatively adjudicates the output result among Fig. 3.
Table 1