CN106376041B - A kind of name data network mobility switching method predicted using ELM - Google Patents
A kind of name data network mobility switching method predicted using ELM Download PDFInfo
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- CN106376041B CN106376041B CN201610872562.4A CN201610872562A CN106376041B CN 106376041 B CN106376041 B CN 106376041B CN 201610872562 A CN201610872562 A CN 201610872562A CN 106376041 B CN106376041 B CN 106376041B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
- H04W36/0016—Hand-off preparation specially adapted for end-to-end data sessions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/12—Reselecting a serving backbone network switching or routing node
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Abstract
The present invention proposes a kind of name data network mobility switching method predicted using ELM, the shift position of the producer is predicted by introducing ELM extreme learning machine prediction algorithm, and pass through pre-configured network, when the producer switches, consumer can still enjoy seamless content delivery service.Original forwarding table in the network architecture is reconstructed in method, devise control packet, to realize the pre-configuration to network, router is set for the response mode of different type control packet, and the pre-configuration of network is saved or restored according to the success or not of prediction result, it is transparent that this method makes the mobile handoff of the producer satisfy the needs of consumers.By introducing prediction process, this method is different from the subsequent adjustable strategies of existing mobility switching method, the network equipment is pre-configured progress synchronous with content transmission before the handover, promotes response speed of the content to user with low bandwidth cost, reduces because mobility switching brings the extra latency of content response.
Description
Technical field
The present invention relates to producer's terminal in name data network (Named_Data Networking, NDN) environment is mobile
Property switching problem, in particular to it is a kind of introduce ELM position prediction algorithm switching occur before pre-switch method.
Background technique
1, NDN background
With the development of cybertimes, people are gradually changed into information from initial fixed service for the application of network
Acquisition and content distribution, since the existing network architecture based on ip increasingly shows its deficiency, then from eighties of last century 50
The exploration for new network framework is risen from age, ICN (Information Centric Networking, in information
Heart network) thought be suggested.Based on ICN thought, the researchers of different regions propose a variety of different network racks
Structure, CCN (Content_Centric Networking, content center network) are a wherein important branches, are passed through again later
It crosses development and forms NDN (Named_Data Networking) framework.
2, mobility switching background and common switching method under NDN scene
Terminal mobility support is one of the main problem studied under NDN framework.Terminal mobility (Mobility) divides again
For consumer end (Consumer) mobility and two kinds of mobility of producer end (Producer).For the former, customer requests
It is moved after content, data packet traces back to the previous position of consumer and cannot be received by consumer, solves this problem only
Consumer is needed to retransmit content interest packet, which can find content in network-caching or producer end.For
The latter, since consumer and network node cannot perceive the movement at producer end, the request that consumer sends is routed to life
The original position of production person and corresponding content cannot be found, such case continues to that the movement at producer end is perceived by network node
And the routing table of router node is modified.
Up to the present, there are the solutions of at least two producer end mobility problems, are based on rally point respectively
The mobility support scheme of (rendeznous point) and the mobility support for being based on indirection point (indirtecion point)
Scheme.In previous scheme, rally point server is responsible for persistently tracking the location information of the producer, and in customer requests' failure
Information is informed into consumer, the program is larger because of switching bring time delay；In latter scheme, indirect point server is responsible in matching
Hold the position of prefix and producer's access point, consumer can lead in the case where ignoring producer's access point with the producer
Believe, the process of encapsulation and the deblocking of data packet increases the complexity of repeating process in the program, and the normal communication time is caused to become
It is long.And above two scheme is all the later Configuration network in the movement of producer end, the communication of the person of resuming production and consumer,
Belong to passive countermeasure.
3, extreme learning machine (ELM) algorithm brief introduction
The problems such as extreme learning machine is a kind of feedforward neural network, can be used for feature learning, classification, cluster, recurrence.Due to
Its succinct structure and higher arithmetic speed, while local optimum can be fallen into avoid result, it has obtained in recent years wider
Using, and extend to complex field.
ELM algorithm model is as follows:H β=T can be denoted as.Wherein H
For hidden layer output matrix, β is output layer weight, and has β=H'T, and wherein H' is the Moore-Penrose generalized inverse matrix of H.
ELM algorithm generally comprises three steps:
Given training set N={ (xi,ti)|xi,∈Rn,ti∈Rm.i=1 ..., N }, activation primitive g (z) and hidden layer section
Point amount fi,
Step 1: assigning input weight ω and bias bi(i=1 ..., N)) any initial value；
Step 2: calculating hidden layer output matrix H；
Step 3: calculating output layer weight beta.
After training, that is, the ELM network generated can be used to be predicted.
Summary of the invention
It is an object of the invention to propose a kind of application ELM prediction for the mobility switching problem in NDN network environment
Name data network mobility switching method, this method by introduce ELM prediction algorithm producer position is predicted,
Network is pre-configured before switching to cope with imminent switching, belongs to active countermeasure, to the maximum extent
Reduce the mobile time delay for bringing consumer of the producer.
In order to achieve the above object, the invention adopts the following technical scheme:
Predict producer's terminal in the position of subsequent time according to the historical position information of producer's terminal using ELM algorithm
It sets；If determining that producer's terminal will switch according to prediction result, using control packet to the FIB of router in network into
Row is pre-configured, and retains existing content forward-path L by being pre-configured to be inNOn the basis of establish and the obtained producer's terminal of prediction
The corresponding content forward-path L in positionN+1, and content forward-path L is kept before subsequent time reachesNAnd LN+1It carries out simultaneously
The forwarding of interest packet；If prediction result is correct, the pre-configuration of network is saved, by saving content forward-path by LN
Switch to LN+1If prediction result mistake, network pre-configuration is restored, by restoring content forward-path by LN+1It cuts
Shift to LN。
The switching method specifically includes the following steps:
1) former access point router uses ELM algorithm, predicts the position of producer's terminal subsequent time；Former access point route
Device, which predicts producer's terminal, will switch to new access point, generate pre- modification packet and route via core router to new access point
Device forwarding is modified the FIB of each router on pre- modification packet forward-path by modifying packet in advance, in advance so that interest packet
It can be forwarded simultaneously to former access point router and new access point router；Wherein, former access point router is producer's terminal
In the edge router of current time access, new access point router is that producer's terminal routes at the edge that new access point accesses
Device；
If 2) producer's terminal occurs mobile and obtains connection with the new access point router in the subsequent time,
Modification confirmation packet is generated by the new access point router, and according to the path opposite with pre- modification packet forward-path via core
Router is sent to former access point router, will be turned by the core router to former access point router by modification confirmation packet
Hair path is deleted from the FIB of corresponding router, and by the forward-path by the core router to new access point router
It is stored in the FIB of corresponding router, so that interest coating is forwarded at new access point router；
If 3) producer's terminal does not move in the subsequent time, still attach on the former access point router,
Modification is then generated by former access point router and cancels packet, and according to pre- modification packet forward-path forwarding, cancelling packet by modification makes
It obtains each router on the path and cancels the operation modified in advance, network configuration is restored to before pre-configuration, and interest packet is still turned
It is dealt at the former access point router.
The step 1) specifically includes the following steps:
1.1) edge router is according to producer's terminal historical position information, using ELM algorithm, predicts producer's terminal
The position of subsequent time；
1.2) when edge router predicts producer's terminal and will switch, pre- modification packet Pre_modify is generated,
And forwarded to core router, it include the prefix of the provided content of producer's terminal in pre- modification packet Pre_modify, and
Mark position 0；
1.3) intermediate router between former access point router and core router searches pre- modification packet Pre_ in FIB
The arrival port numbers of pre- modification packet are moved to Pre_ by Face_list list item by the corresponding list item of content prefix in modify
In face list item；
1.4) core router searches the corresponding list item of content prefix in pre- modification packet Pre_modify in FIB, will
The arrival port numbers of pre- modification packet move to Pre_face list item by Face_list list item, and add court in Pre_face list item
The port numbers of new access point router forwarding；Core router will continue behind the mark position 1 of pre- modification packet Pre_modify to
The forwarding of new access point router；
1.5) intermediate router between core router and new access point router searches pre- modification packet in fib table
The corresponding list item of content prefix in Pre_modify adds the end forwarded towards new access point router in Pre_face list item
Slogan；
1.6) after new access point router receives pre- modification packet Pre_modify, forwarding successfully letter is returned by original route
Number, pre- process of modifying is completed, and interest packet is turned simultaneously according to the port numbers in Face_list list item and Pre_face list item
Hair.
The step 2) specifically includes the following steps:
If producer's terminal and new access point router obtain connection, success is predicted, carry out step 2.1) extremely
2.5):
2.1) new access point router generates modification confirmation packet Modify_confirm, by mark position 1 in packet, and to original
Access point router forwarding；
2.2) intermediate router between core router and new access point router receives modification confirmation packet Modify_
After confirm, the port numbers in Pre_face list item are moved into Face_list list item；
2.3) after core router receives modification confirmation packet Modify_confirm, by the arrival port numbers of the packet by Pre_
Face_list list item is moved in face list item, deletes remaining port numbers in Pre_face list item, and modification confirmation is wrapped
The mark position 0 of Modify_confirm；
2.4) intermediate router between former access point router and core router receives modification confirmation packet Modify_
After confirm, the port numbers in Pre_face list item are deleted；
2.5) it after former access point router receives modification confirmation packet, returns and forwards successful signal, modification confirmation process is complete
At；It is present that interest packet according to the Face_list list item in modified corresponding router fib table is routed to producer's terminal
Position.
The step 3) specifically includes the following steps:
If producer's terminal does not move, still attaches on former access point router, then prediction of failure, walked
It is rapid 3.1) to 3.5):
3.1) former access point router generates modification and cancels packet Modify_cancel, by mark position 1 in packet, and to new
Access point router forwarding；
3.2) intermediate router between former access point router and core router receives modification cancellation packet Modify_
After cancel, the port numbers in Pre_face list item are moved in Face_list list item；
3.3) after core router receives modification cancellation packet Modify_cancel, by the arrival port numbers of the packet by Pre_
It is moved in face list item in Face_list list item, deletes remaining port numbers in Pre_face list item, and packet is cancelled into modification
The mark position 0 of Modify_cancel；
3.4) intermediate router between core router and new access point router receives modification cancellation packet Modify_
After cancel, the port numbers in Pre_face list item are deleted；
3.5) new access point router receives modification cancellation packet Modify_cancel, returns and forwards successful signal, completes
Modify cancellation process；Interest packet is routed to producer's terminal original position according to Face_list list item in corresponding router FIB.
Edge router is repaired in advance when being predicted the position of subsequent time producer terminal using ELM algorithm, predicting switching
Change network configuration and confirmation or cancel modification, is carry out synchronous with the normal communication of producer's terminal.
Edge router acquires producer's terminal location coordinate with time interval t, is sat using the position of n-hour before the terminal
It is denoted as predicting the position coordinates at terminal N+1 moment for the input of ELM network；After prediction, the terminal is in N+1
The actual position coordinate at quarter is added in real time in the input value of ELM network, enables the prediction result of subsequent time with this
The current state of terminal and update.
Increase pre- modification port list item Pre_face in the FIB of the name data network, pre- port list item of modifying is used
The fib table of corresponding router is temporarily modified in the handoff predictions result of response terminal, and is different from original forwarding port
List item；Pre- modification port can be saved according to the correctness of prediction result as interim forwarding port, in future or
It is cancelled.
The network configuration that the control packet is switched based on realization towards mobility is designed, including modifies packet Pre_ in advance
Packet Modify_cancel is cancelled in modify, modification confirmation packet Modify_confirm and modification；It is included at least in pre- modification packet interior
Hold three prefix, flag bit and locator fields, modification confirmation packet and modification cancel packet and include at least content prefix and flag bit
Two fields.
The pre- modification packet is pre-configured for being pre-configured router, modification confirmation packet for saving when predicting successfully, modification
Cancel packet for cancelling pre-configured operator when prediction of failure；Locator fields in pre- modification packet are used to position core router,
The core router is connected with access point router after the switching of former access point router and prediction；Router is according to flag bit word
Section value determines the movement or additions and deletions to pre- modification port.
The invention has the following advantages:
Switching predict by introducing ELM prediction algorithm in the present invention, to shift to an earlier date before handover takes place
Configuration network provides possibility, belongs to the adjustable strategies in advance of active, to solve the problems, such as that the mobility support under NDN framework provides
New thinking；Present invention application ELM prediction algorithm makes network configuration adjustment can be between consumer and the producer just
Normal communication synchronization carries out, may be implemented handover operation satisfy the needs of consumers it is transparent.The method of the present invention is different from existing mobility switching
The subsequent adjustable strategies of method, network equipments configuration is synchronous with content transmission before the handover to be carried out, in the promotion of low bandwidth cost
Hold the response speed to user, reduces because mobility switching brings the extra latency of content response.
Detailed description of the invention
Fig. 1 is the name data network mobility switching method flow chart predicted using ELM；
Fig. 2 is the flow chart that producer shift position is predicted using ELM algorithm；
Fig. 3 is three kinds of packet formats of modified fib table format and invention；
Fig. 4 is the name data network mobility switching method analysis model predicted using ELM；
Fig. 5 is the timing diagram for the name data network mobility handoff procedure predicted using ELM；
Fig. 6 is the simulation result that producer's movement and switching are predicted using ELM.
Specific embodiment
In order to which the contents of the present invention, effect and advantage is more clearly understood, with reference to the accompanying drawings and examples to this
Invention is described in detail.
Network configuration modification after existing method all occurs based on the switching of producer's terminal is cut to adapt to mobility
Bring variation is changed, a kind of passively subsequent adjustable strategies are belonged to, for example, either rally point solution or indirection point solution
Certainly scheme is all to carry out configuration adjustment to network after switching occurs, there is time delay, cannot achieve really seamless
Switching.And the present invention is the switching method of limits of application learning machine algorithm forecasting mechanism, becomes passive reply and copes with into active.This hair
The bright specific method for providing complete limit of utilization learning machine algorithm prediction result and carrying out network configuration, it is former including modification
Fib table is wrapped with three kinds of controls are devised, and sets response of the router for three kinds of control packets.Referring to Fig. 1, the present invention passes through
ELM prediction algorithm is introduced in the mobility support problem of name data network, having broken existing method can only adjust after handover
Whole limitation, to realize that real seamless switching provides possibility.Strategic process of the invention is illustrated in Fig. 1, passes through prediction
The movement of producer's terminal modifies network according to prediction result to predict the switching that will occur in advance, it is contemplated that pre-
The accuracy problem of method of determining and calculating is determined according to prediction success or failure to pre- modification content preservation or revocation.This method advantage be no matter
Predict success or not, do not affect consumer and normally obtain content so that switching satisfy the needs of consumers it is transparent.
(1) edge router predicts its subsequent time position according to producer's terminal current location
Prediction process includes the following steps, referring to fig. 2:
1) position coordinates of producer's terminal are obtained using constant duration mode.Setting time interval t, for certain all one's life
Production person's terminal is collected its primary position coordinates every time t and is stored, storage N item (i.e. top n moment) terminal location coordinate coexists
(interval time t is arranged in the factors such as computing capability according to producer's moving velocity of terminal and edge router and terminal location is sat
Mark quantity N).Remember that the i-th moment terminal location coordinate is (xi,yi), i=1,2 ... N, wherein xiFor horizontal axis relative coordinate or latitude
Coordinate, yiFor longitudinal axis relative coordinate or longitude coordinate, then N position coordinates can be denoted as matrix:
2) using position coordinates matrix X as the input of ELM network, the position coordinates of terminal described in the N+1 moment are predicted
X'N+1, i.e. (x'N+1,y'N+1)。
3) it calculates and the coordinate (X'N+1) apart from nearest router R (if predicting successfully, using the router as the producer
The access point router of terminal).
4) after interval time t, the actual conditions (switching judging and execution according to network itself that are switched according to terminal
Strategy), the new position coordinates (x of collection terminalN+1,yN+1), i.e. actual position coordinate (the X at N+1 momentN+1), and this coordinate is added
Enter position coordinates matrix, simultaneously because the position coordinates that N number of moment is used only are predicted, therefore, removes position coordinates matrix
The earliest position coordinates of middle acquisition time, to complete the update of matrix.
5) step 2) is repeated to step 4), uses the position coordinates of updated Matrix prediction subsequent time terminal.
(2) original FIB (Forwards Forwarding table) structure is modified
The switching of producer's terminal can cause the variation of router forwarding port, the port meeting forwarded towards former terminal position
It is moved out of FIB, FIB can be added into simultaneously towards the port of new terminal position forwarding.It is determined to meet according to prediction success or failure
Pre- modification content is saved or cancelled, referring to fib table structure modified in Fig. 3, the present invention increases pre- modification end in former FIB
Mouth (Pre_face) list item, the port which needs to change for temporarily storing router pre-configuration (i.e. modification in advance) process.
In pre-provisioning procedure, router will connect the port in former access point router direction by the Face_list table of specific content prefix
Item moves in Pre_face list item, and deletes from FIB when predicting successfully；Router will connect new access point router direction
Port be added in the Pre_face list item of specific content prefix, and moved in Face_list list item when predicting successfully.It is special
Determine content and refers to content provided by the producer of prediction switching.In former FIB, Face_list list item is for storing corresponding content
Forwarding port numbers.
The structure of the control packet of (three) three kinds of modification network configurations, generates position, pass-through mode and effect at formation condition
Referring to Fig. 3, the structure of pre- modification packet (Pre_modify) includes: 1. content names (Content_prefix) that is, will
The title of the provided content of producer's terminal to switch.2. flag bit (Flag), router is according to Packet type and the field
Value determines the movement or additions and deletions to pre- modification port.3. locator (Locator), for positioning particular core router,
It is connected with access point router after the switching of former access point router and prediction.4. optional part (Nonce), opens up for function
Exhibition.Modification is cancelled packet (Modify_cancel) and is forwarded along the forward-path of pre- modification packet, modification confirmation packet (Modify_
Confirm it) is forwarded along the reverse path of pre- modification packet forwarding, therefore there is no locator (Locator) field in both packets.
1, it pre- modification packet (Pre_modify): when predicting the switching of producer's terminal, is given birth to by former access point router
At, the new access point router predicted is sent to via core router, it is pre- to the FIB progress of the all-router of forwarding process
It modifies to handle the handoff procedure of prediction.
2, modification confirmation packet (Modify_confirm): when predicting successfully, producer's terminal takes with new access point router
It must connect, be generated by new access point router, former access point router is sent to via core router, to the router in path
Pre- modification content saved.
3, packet (Modify_cancel) is cancelled in modification: when prediction of failure, producer's terminal does not switch, is accessed by original
Point router generates, and the access point new router of prediction is sent to via core router, and the router in path is made in cancellation
Pre- modification.
(4) response of the intermediate router for three kinds of control packets
If 1, the flag bit in packet is 0:
(1) Pre_modify packet is received, receiving port is numbered by Content_prefix corresponding table item Face_ in FIB
List is moved in Pre_face；
(2) Modify_confirm packet is received, receiving port is numbered by Content_prefix corresponding table item in FIB
It is deleted in Pre_face；
(3) Modify_cancel packet is received, receiving port is numbered by Content_prefix corresponding table item in FIB
It is deleted in Pre_face；
If 2, the flag bit in packet is 1:
(1) Pre_modify packet is received, receiving port number is added to Content_prefix corresponding table item in FIB
In Pre_face；
(2) Modify_confirm packet is received, receiving port is numbered by Content_prefix corresponding table item in FIB
Pre_face is moved in Face_list；
(3) Modify_cancel packet is received, receiving port is numbered by Content_prefix corresponding table item in FIB
Face_list is moved back into Pre_face；
Port from interest packet to Pre_face and Face_list middle port in processing mobility handoff procedure by turn simultaneously
Hair.It is the port that will be deleted or the new port that Face_list will be added in Pre_face list item, and simultaneously to all
The pass-through mode of port forwarding interest packet makes no matter when producer's terminal moves, interest packet can in former access point or
Corresponding contents are found at person's new access point without extra latency.
(5) the seamless switching process of ELM algorithm is used
Referring to fig. 4, consumer Consumer is requesting content/para/1.avi of producer Producer, original access
Point router R_old calculates the position of Producer subsequent time by ELM algorithm, if obtaining the producer according to the position prediction
New access point router R_new will be switched to by former access point router R_old, R_old generates Pre_modify packet, packet at this time
Middle content is entitled/para/1.avi, mark position 0, the content of locator is the core router that can connect R_old and R_new
R_core forwards the Pre_modify packet through R_core to R_new:
301, intermediate router R_middle1 receives after the Pre_modify packet lookup/para/ in the FIB of oneself
The corresponding list item of 1.avi, then modifies the FIB of oneself, i.e., by packet arrival port (number 2) from/para/1.avi
Corresponding Face_list is moved to/the corresponding Pre_face of para/1.avi in；
302, after core router R_core receives the Pre_modify packet will packet in mark position 1, and oneself
The corresponding list item of lookup/para/1.avi in FIB, then modifies the FIB of oneself, i.e., by packet arrival port, (number is
2) be moved to from/corresponding the Face_list of para/1.avi/the corresponding Pre_face of para/1.avi in, and in the Pre_
The port (number 1) that addition is forwarded and (forwarded towards R_new) in face；
303, after intermediate router R_middle2 receives the Pre_modify packet in the FIB of oneself lookup/para/
The corresponding list item of 1.avi, then modifies the FIB of oneself, i.e., adding in/corresponding the Pre_face of para/1.avi needs
Forward and (forward towards R_new) port numbers (number 2) of the packet；
R_new is received after the Pre_modify packet by the original route return success signal for forwarding the Pre_modify packet
To R_old, so far modification process is completed in advance.
If predicting successfully, i.e. Producer and R_new obtain connection, then generate Modify_confirm packet (packet by R_new
Middle mark position 1), and forwarded into net.After intermediate router R_middle2 receives the Modify_confirm packet, to oneself
FIB modify, i.e., the port that the number added in step 303 is 2 is moved to the/corresponding Face_ of para/1.avi
In list；Core router R_core receive after the Modify_confirm packet will mark position 0 in packet, and by the FIB of oneself
In receive the port numbers 1 (port that the number added in step 302 is 1) of the packet by the/corresponding Pre_ of para/1.avi
Face is moved to/the corresponding Face_list of para/1.avi in, delete remaining raw content forwarding port in the Pre_face
(port that the number moved in step 302 is 2)；After intermediate router R_middle1 receives the Modify_confirm packet
The FIB of oneself is modified, i.e. the port that number is 2 in the corresponding Pre_face of general/para/1.avi is (i.e. in step 301
The port that mobile number is 2) it deletes, R_old is received after the Modify_confirm packet by the forwarding Modify_confirm
The original route of packet returns to success signal to R_new, completes modification confirmation process.Producer is switched to new edge router
(referred to R_new), interest packet are routed to the present position Producer according to modified fib table (after mobile).
If prediction of failure, Producer is not moved, is still attached to R_old, is then generated Modify_ by R_old
Cancel packet (mark position 1 in packet), and forwarded into net.Intermediate router R_middle1 receives the Modify_cancel packet
The FIB of oneself is modified afterwards, i.e., port (the i.e. step for being 2 by the number in the/corresponding Pre_face of para/1.avi
The port that the number moved in 301 is 2) be moved back into/the corresponding Face_list of para/1.avi in；Core router R_core
Receive after the Modify_cancel packet will mark position 0 in packet, and the port that the number of the packet is 2 will be received in the FIB of oneself
Be moved back into by/corresponding the Pre_face of para/1.avi/the corresponding Face_list of para/1.avi in, remove the Pre_face
In remaining forwarding port (number 1, i.e., the port that the number added in step 302 is 1)；Intermediate router R_middle2
After receiving the Modify_cancel packet, the FIB of oneself is modified, is i.e. is compiled in the corresponding Pre_face of general/para/1.avi
Number for 2 port (port that the number added in step 303 is 2) delete；After R_new receives the Modify_cancel packet
Modification cancellation process is completed by forwarding the original route of the Modify_cancel packet to return to success signal R_old.Producer
It still attaches on former edge router (referred to R_old), before interest packet is routed to Producer prediction according to former fib table
Position.
If predicting movement, but shift position prediction error, such case possibility occurrence be it is smaller, if it happens
It can be handled according to existing subsequent strategy.
So far, the primary complete seamless switching process using ELM algorithm is completed.
(6) using the timing of the NDN mobility handoff process of ELM prediction
Referring to Fig. 5, wherein 401,402,403 illustrate when being in the different phase for the treatment of process, for Consumer
Interest packet Interest Different treatments:
401, after completing pre- modification process, R_ is simultaneously forwarded to according to fib table after Interest packet arrival R_core
Old and R_new always has the Interest in place at one to be responded so that no matter whether Producer has been carried out switching,
Data packet is returned to Consumer, and Consumer is not relevant for whether Producer has occurred and that switching；
If 402, predicting that successfully, after completing to modify confirmation process, Producer is connect with R_new at this time, and net
The content that FIB in network also provides Producer has been directed toward R_new, so the Interest packet meeting that Consumer is issued at this time
R_new is forwarded to by R_core and obtains content from Producer；
If 403, prediction of failure, after completing to modify cancellation process, network configuration is reduced, and Consumer is still pressed
It is communicated according to the path before prediction with Producer, i.e. the Interest packet that Consumer is issued can be forwarded to R_ by R_core
Content is obtained at old and from Producer.
(7) emulation experiment
Referring to Fig. 6, in virtual production person's Producer moving projection, mobility model uses random walk model
(Random Walk Mobility Model), the producer is with stochastic variable speed speed and direction direction from present bit
It sets mobile to the next position, wherein speed speed obeys being uniformly distributed on section [speedmin, speedmax], direction
Direction obeys being uniformly distributed on section [0,2 π].Present speed and direction and the speed of last time calculating and direction are only
It is vertical.If the producer is moved to simulating area edge, rebound according to next moving direction.Producer position is every time interval t
It calculates primary.
Mobility model is generated using BonnMotion emulation platform, is carried out using MATLAB r2014b based on ELM algorithm
Prediction calculates.For the sake of drawing simplicity, the movement of a producer is only emulated every time.In Fig. 6, solid line, which is that the producer is practical, to be moved
Track, dotted line are the producer's motion track predicted using ELM algorithm, and dot is router, and regular hexagon is router covering
Cell boarder.
Simulation parameter design is as shown in the table:
| Simulation parameter | Parameter value configuration |
| Traverse range | 1000m |
| Vertically move range | 1000m |
| Producer's maximum movement speed | 15m/s |
| Producer's minimum translating velocity | 5m/s |
| Position counting period t | 10s |
| Radius of society | 144m |
| The producer moves times N | 600 times |
| ELM network the number of hidden nodes | 2000 |
It is N that note, which calculates the mobile total degree of the producer, then the accuracy rate of handoff predictions
Wherein NeFor the number of prediction error, prediction error includes mistakenly predicting whether to switch and be switched to mistake
Cell.
Simulation training predictablity rate is 99.41%, reaches higher accuracy rate.
In short, the invention proposes the name data networks of application ELM prediction by introducing forecasting mechanism in handoff procedure
Network mobility switching method, effectively improves switching efficiency, firstly, edge router operating limit learning machine algorithm, according to
The current location information of terminal, predicts the position of its subsequent time, and edge router connects predicting with it according to prediction result
Certain terminal connect will switch when will leave its range, and terminal and new router is made to establish connection.By introducing prediction process,
Allow router to make handover operation in advance to the movement of terminal, effectively reduce the flow loss in handoff procedure, saves
About bandwidth, shortens time delay.
The present invention introduces ELM extreme learning machine prediction algorithm in name data network mobility switching problem research,
The shift position of the producer is predicted, and by pre-configured network, when the producer switches, consumer can still be enjoyed
By seamless content delivery service.It is reconstructed original forwarding table in the network architecture in method, devises and is repaired for network configuration
The control packet changed sets router for the response mode of different type control packet to realize the pre-configuration to network, and
The pre-configuration of network is saved or restored according to the success or not of prediction result, this method makes the mobile handoff of the producer
It satisfies the needs of consumers transparent.By introducing prediction process, this method is different from the subsequent adjustable strategies of existing mobility switching method,
The network equipment is pre-configured progress synchronous with content transmission before the handover, promotes response speed of the content to user with low bandwidth cost
Degree is reduced because mobility switching brings the extra latency of content response.
Claims (3)
1. it is a kind of using ELM predict name data network mobility switching method, it is characterised in that: the switching method include with
Lower step:
Predict producer's terminal in the position of subsequent time according to the historical position information of producer's terminal using ELM algorithm；
If determining that producer's terminal will switch according to prediction result, carried out using FIB of the control packet to router in network
It is pre-configured, retains existing content forward-path L by being pre-configured to be inNOn the basis of establish the producer terminal obtained with prediction
The corresponding content forward-path L in positionN+1, and content forward-path L is kept before subsequent time reachesNAnd LN+1It carries out simultaneously emerging
Interest packet forwarding；If prediction result is correct, pre-configuration is saved, by saving content forward-path by LNIt switches to
LN+1If prediction result mistake, restores pre-configuration, by restoring content forward-path by LN+1Switch to LN；
The switching method specifically includes the following steps:
1) former access point router uses ELM algorithm, predicts the position of producer's terminal subsequent time；Former access point router is pre-
New access point will be switched to by measuring producer's terminal, be generated pre- modification packet and be turned via core router to new access point router
Hair modifies the FIB of each router on pre- modification packet forward-path by modifying packet in advance in advance, so that interest packet can be with
It is forwarded simultaneously to former access point router and new access point router, realizes and be pre-configured；Wherein, former access point router is production
The edge router that person's terminal accesses at current time, new access point router are producer's terminals on the side that new access point accesses
Edge router；
2) if producer's terminal occurs mobile and obtains connection with the new access point router in the subsequent time, by institute
It states new access point router and generates modification confirmation packet, and routed according to the path opposite with pre- modification packet forward-path via core
Device is sent to former access point router, will be by the forwarding road of the core router to former access point router by modification confirmation packet
Diameter is deleted from the FIB of corresponding router, and will be stored in by the forward-path of the core router to new access point router
The FIB of corresponding router, so that interest coating is forwarded at the new access point router；
If 3) producer's terminal does not move in the subsequent time, still attach on the former access point router, then by
Former access point router generates modification and cancels packet, and according to pre- modification packet forward-path forwarding, cancels packet by modification so that should
Each router on path cancels the operation modified in advance, and network configuration is restored to before pre-configuration, and interest packet is still forwarded to
At the original access point router；
The step 1) specifically includes the following steps:
1.1) edge router is according to producer's terminal historical position information, using ELM algorithm, predicts one under producer's terminal
The position at moment；
1.2) when edge router predicts producer's terminal and will switch, pre- modification packet Pre_modify is generated, and to
Core router forwarding, the prefix in Pre_modify comprising the provided content of producer's terminal is wrapped in pre- modification, and is indicated
Position 0；
1.3) intermediate router between former access point router and core router searches pre- modification packet Pre_modify in FIB
In the corresponding list item of content prefix, the arrival port numbers of pre- modification packet are moved into Pre_face list item by Face_list list item
In；
1.4) core router searches the corresponding list item of content prefix in pre- modification packet Pre_modify in FIB, will repair in advance
The arrival port numbers for changing packet move to Pre_face list item by Face_list list item, and in Pre_face list item addition towards newly connecing
The port numbers of access point router forwarding；Core router will continue behind the mark position 1 of pre- modification packet Pre_modify to newly connecing
The forwarding of access point router；
1.5) intermediate router between core router and new access point router searches pre- modification packet Pre_ in fib table
The corresponding list item of content prefix in modify adds the port forwarded towards new access point router in Pre_face list item
Number；
1.6) it after new access point router receives pre- modification packet Pre_modify, is returned by original route and forwards successful signal, in advance
Modification process is completed, and interest packet is forwarded simultaneously according to the port numbers in Face_list list item and Pre_face list item；
The step 2) specifically includes the following steps:
If producer's terminal and new access point router obtain connection, success is predicted, carry out step 2.1) to 2.5):
2.1) new access point router generates modification confirmation packet Modify_confirm, accesses by mark position 1 in packet, and to original
Point router forwarding；
2.2) intermediate router between core router and new access point router receives modification confirmation packet Modify_
After confirm, the port numbers in Pre_face list item are moved into Face_list list item；
2.3) after core router receives modification confirmation packet Modify_confirm, by the arrival port numbers of the packet by Pre_face
Face_list list item is moved in list item, deletes remaining port numbers in Pre_face list item, and modification is confirmed into packet Modify_
The mark position 0 of confirm；
2.4) intermediate router between former access point router and core router receives modification confirmation packet Modify_confirm
Afterwards, the port numbers in Pre_face list item are deleted；
2.5) it after former access point router receives modification confirmation packet Modify_confirm, returns and forwards successful signal, modification
Confirmation process is completed；Interest packet is routed to the producer according to the Face_list list item in modified corresponding router fib table
The present position of terminal；
The step 3) specifically includes the following steps:
If producer's terminal does not move, still attach on former access point router, then prediction of failure, carries out step
3.1) to 3.5):
3.1) packet Modify_cancel is cancelled in former access point router generation modification, accesses by mark position 1 in packet, and to new
Point router forwarding；
3.2) intermediate router between former access point router and core router receives modification cancellation packet Modify_cancel
Afterwards, the port numbers in Pre_face list item are moved in Face_list list item；
3.3) after core router receives modification cancellation packet Modify_cancel, by the arrival port numbers of the packet by Pre_face
It is moved in list item in Face_list list item, deletes remaining port numbers in Pre_face list item, and packet Modify_ is cancelled into modification
The mark position 0 of cancel；
3.4) intermediate router between core router and new access point router receives modification cancellation packet Modify_cancel
Afterwards, the port numbers in Pre_face list item are deleted；
3.5) new access point router receives modification cancellation packet Modify_cancel, returns and forwards successful signal, completes to modify
Cancellation process；Interest packet is routed to producer's terminal original position according to Face_list list item in corresponding router FIB；
Increase pre- modification port list item Pre_face in the FIB of the name data network, pre- port list item of modifying is for ringing
It answers the handoff predictions result of terminal temporarily to modify the fib table of corresponding router, and is different from original forwarding port list item；
Pre- modification port can be saved or be taken in future as interim forwarding port according to the correctness of prediction result
Disappear；
The network configuration that the control packet is switched based on realization towards mobility is designed, including modifies packet Pre_ in advance
Packet Modify_cancel is cancelled in modify, modification confirmation packet Modify_confirm and modification；It is included at least in pre- modification packet interior
Hold three prefix, flag bit and locator fields, modification confirmation packet and modification cancel packet and include at least content prefix and flag bit
Two fields；
The pre- modification packet is pre-configured for being pre-configured router, modification confirmation packet for saving when predicting successfully, and modification is cancelled
Packet is for cancelling pre-configured operator when prediction of failure；Locator fields in pre- modification packet are for positioning core router, the core
Heart router is connected with access point router after the switching of former access point router and prediction；Router takes according to flag bit field
Value determines the movement or additions and deletions to pre- modification port.
2. a kind of name data network mobility switching method predicted using ELM, feature exist according to claim 1
In: edge router using ELM algorithm prediction subsequent time producer terminal position, predict switching when modify network in advance
Modification is cancelled in configuration and confirmation, is carry out synchronous with the normal communication of producer's terminal.
3. a kind of name data network mobility switching method predicted using ELM, feature exist according to claim 1
In: edge router acquires producer's terminal location coordinate with time interval t, is made using the position coordinates of n-hour before the terminal
For the input of ELM network, the position coordinates at terminal N+1 moment are predicted；After prediction, the terminal is at the N+1 moment
Actual position coordinate is added in real time in the input value of ELM network, enables the prediction result of subsequent time with the terminal
Current state and update.
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| CN108092899B (en) * | 2018-01-05 | 2020-07-28 | 北京工业大学 | Routing strategy updating method based on named data network under MANET environment |
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