CN106790638B

CN106790638B - Name data transmission method and system based on active cache in data network

Info

Publication number: CN106790638B
Application number: CN201710015863.XA
Authority: CN
Inventors: 芮兰兰; 邱雪松; 杨穗佳; 李文璟; 王颖
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2017-01-10
Filing date: 2017-01-10
Publication date: 2019-10-11
Anticipated expiration: 2037-01-10
Also published as: CN106790638A

Abstract

The embodiment of the invention provides data transmission methods and system based on active cache in a kind of name data network, this method comprises: being applied to terminal, when terminal starts mobile, obtain the first strength time sequence and first rate time series.According to the first strength time sequence, the switching time started that terminal and first node disconnect is determined.It according to switching time started and first rate time series, determines that terminal has requested that, but is unable to complete before node switching starts received to cache contents.Sending first interest packet of the mark to cache contents to first node will be cached in the corresponding Node subsets of first node so that first node receives and according to the first interest packet to cache contents.After terminal switching is connected to second node, send to second node for requesting the second interest packet to cache contents.Receive by second node according to the second interest packet, obtain and send from the corresponding Node subsets of first node to cache contents.

Description

Name data transmission method and system based on active cache in data network

Technical field

The present invention relates to radio computer network fields of communication technology, are based on actively more particularly to naming in data network The data transmission method and system of caching.

Background technique

NDN (Named Data Networking names data network) is a kind of new network frame for being different from IP network Structure defers to the design philosophy of ICN (Information-Centric Networking, information centre's network).NDN with data and Centered on information, hierarchical to numerical nomenclature with take replace current internet in IP address, and use content consumer with The operation of contents producer is driven in time and the publish/subscribe mode being spatially separating, all communications by content consumer.NDN In only Interest Message (interest packet) and two kinds of data groupings of Content Object (content packet).Request certain number According to when, consumer by terminal send carry data name interest packet, by NDN routing node multicast outward forwarding, press Title finds data；When the data name of contents producer is matched with interest packet, corresponding content packet will press the forwarding of interest packet Route reversely reaches the content consumer (terminal) for issuing request.In addition, NDN uses caching, content packet meeting in general net By way of node along road cache, interest packet is before reaching the producer, it is possible to which having had arrived at can matched content packet pair This node improves network response speed to reduce the time delay for obtaining data.

NDN supports data transmission of the terminal under moving condition.It is directed to terminal mobility problem in the prior art, at end End node switching be when will start, and transmission types are the request message of " consumer's movement starts " to its former access node, simultaneously Terminal stops sending interest packet；For terminal original access node according to the request of " consumer's movement starts ", it is in situ that caching is sent to terminal The data-message set；After the completion of terminal node switching, former access node updates and the data-message of forwarding cache is new to terminal The node of access.

In the prior art, node switching front and back loss of data in order to prevent, terminal send " consumer's movement starts " After request message, stop sending interest packet.But it is will lead to after the request message that terminal sends " consumer's movement starts " in this way, And before terminal and former access node disconnect, new data can not be received, will cause whole handoff procedure when Prolong increase, in addition, terminal, which is moved to behind new position, does not complete received data from the acquisition of former access node, when equally will cause Prolong, therefore the time delay that data are transmitted in prior art node handoff procedure is high.

Summary of the invention

The embodiment of the present invention is designed to provide the transmission side data based on active cache in a kind of name data network Method and system, to realize the time delay for shortening data transmission in node handoff procedure.Specific technical solution is as follows:

Data transmission method based on active cache in a kind of name data network is applied to terminal, comprising:

When terminal starts mobile, the first strength time sequence and first of the first signal strength and time formation is obtained The first rate time series that transmission rate and time are formed, wherein first signal strength is the terminal and first segment The signal strength connected between point, first transmission rate transmit the speed of data between the terminal and the first node Rate, the first node is by the preceding node connected of terminal node switching；

According to the first strength time sequence, the switching for determining that the terminal is disconnected with the first node starts Time；

According to the switching time started and the first rate time series, determine that the terminal has requested that, but saving Point switching is unable to complete received to cache contents before starting；

The mark first interest packet to cache contents is sent to the first node, so that the first node receives And according to the first interest packet, it is cached to described in the corresponding Node subsets of the first node to cache contents；

After terminal switching is connected to second node, Xiang Suoshu second node sends described wait in caching for requesting The the second interest packet held；

It receives by the second node according to the second interest packet, is obtained from the corresponding Node subsets of the first node It takes and sends described to cache contents.

Data transmission method based on active cache in a kind of name data network is applied to network-side, comprising:

First interest packet of the mark that reception and basis are sent by terminal to cache contents, the content for determining that needs cache are It is described to cache contents, wherein it is described to cache contents be the terminal have requested that, but node switching start before be unable to complete Received content；

It obtains and according to the signal intelligence of entire name data network, determines the corresponding Node subsets of first node, wherein The first node is by the preceding node connected of terminal node switching；

According to the first interest packet, caching it is described to cache contents into the corresponding Node subsets of the first node, So that second node is used to request the second interest packet to cache contents according to what is sent by the terminal, in the first node In corresponding Node subsets, obtain and send it is described to cache contents so that the terminal receive it is described to cache contents, In, the node that connects after the second node is switched by the terminal node.

Data transmission system based on active cache in a kind of name data network is applied to terminal, comprising:

Time series obtains module, for when terminal starts mobile, obtaining the first signal strength and the time is formed the The first rate time series that one strength time sequence and the first transmission rate and time are formed, wherein first signal is strong The signal strength connected between the terminal and first node is spent, first transmission rate is the terminal and described first The rate of data is transmitted between node, the first node is by the preceding node connected of terminal node switching；

Time started computing module, for determining the terminal and described first according to the first strength time sequence The switching time started that node disconnects；

To cache contents determining module, it is used for according to the switching time started and the first rate time series, really The fixed terminal has requested that, but is unable to complete before node switching starts received to cache contents；

First interest packet sending module, for sending mark first interest to cache contents to the first node Packet is cached to the first segment to cache contents for described so that the first node receives and according to the first interest packet In the corresponding Node subsets of point；

Second interest packet sending module, for the terminal switching be connected to second node after, Xiang Suoshu second node It sends for requesting the second interest packet to cache contents；

To cache contents receiving module, for receiving by the second node according to the second interest packet, from described the What is obtained and send in the corresponding Node subsets of one node is described to cache contents.

Data transmission system based on active cache in a kind of name data network is applied to network-side, comprising:

Interest packet receiving module, the first interest packet for receiving and according to the mark sent by terminal to cache contents, Determine that needing the content cached is described to cache contents, wherein it is described to be had requested that cache contents for the terminal, but saving Point switching is unable to complete received content before starting；

Node subsets determining module determines first segment for obtaining and according to the signal intelligence of entire name data network The corresponding Node subsets of point, wherein the first node is by the preceding node connected of terminal node switching；

Cache module, for according to the first interest packet, caching to be described corresponding to the first node to cache contents Node subsets in so that second node according to by the terminal send for requesting the second interest packet to cache contents, In the corresponding Node subsets of the first node, obtain and send it is described to cache contents so that described in the terminal receives To cache contents, wherein the node that the second node connects after being switched by the terminal node.

Data transmission method and system in name data network provided in an embodiment of the present invention based on active cache, terminal Send first interest packet of the mark to cache contents to network-side, and receive data and disconnect to connecting, compared with the prior art in Terminal stops receiving data in advance, on the basis of preventing loss of data, reduce that data in node handoff procedure transmit when Prolong；The node that terminal can may be switched to by network-side simultaneously is cached as Node subsets to cache contents to Node subsets In, terminal passes through the content of Node subsets acquisition request after the completion of switching, can shorten data in node handoff procedure and transmit Time delay.In addition, terminal sends the first data packet to first node, node is facilitated to be cached according to the switching time started wait in caching Hold, has saved cache resources；Caching cost is considered when determining Node subsets, can reduce the expense of caching.Certainly, implement Any product of the invention or method must be not necessarily required to reach all the above advantage simultaneously.

Detailed description of the invention

In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with It obtains other drawings based on these drawings.

Fig. 1 is the schematic diagram of application scenarios of the embodiment of the present invention；

Fig. 2 is the data transmission method based on active cache in the name data network of the embodiment of the present invention, is applied to eventually The flow diagram at end；

Fig. 3 is the data transmission method based on active cache in the name data network of the embodiment of the present invention, is applied to net The flow diagram at network end；

Fig. 4 is a kind of flow diagram of method of the Node subsets of the determination node i of the embodiment of the present invention；

Fig. 5 is the flow diagram of another method of the Node subsets of the determination node i of the embodiment of the present invention；

Fig. 6 is the schematic diagram of the tertiary structure network of the embodiment of the present invention；

Fig. 7 is that the data transmission system based on active cache is applied to terminal in the name data network of the embodiment of the present invention Schematic diagram；

Fig. 8 is that the data transmission system based on active cache is applied to network in the name data network of the embodiment of the present invention The schematic diagram at end.

Specific embodiment

Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other Embodiment shall fall within the protection scope of the present invention.

NDN supports data transmission of the terminal under moving condition, if the switching of node occurs in moving process, terminal is even Request packet is retransmitted after connecing recovery.But biggish time delay, clock synchronization can be generated until establishing to re-request again after connection with new node Prolonging sensitive application will receive larger impact, including teleconference, game on line and currently a popular network video are straight Broadcast equal real time business.Especially in a network not the copy of the data of terminal request when, interest packet must be forwarded to the producer, eventually End obtains data from the producer, causes apparent time delay.Therefore, it is mobile to need to establish a set of more efficiently terminal in NDN Support scheme efficiently reduces the delay problem generated when node switching.

It is the schematic diagram of application scenarios of the embodiment of the present invention referring to Fig. 1, Fig. 1, comprising: 1 node 01 of layer, 2 node 02 of layer are interior Hold consumer 03, contents producer 04.1 node 01 of layer is NDN network edge, the node that terminal device can be directly connected to.1 layer 2 nodes 02 are connected with multiple 1 nodes 01 of layer, farther (communication forwarding hop count is more) apart from terminal device.Node level can be into One step increases, and more high-rise node provides more extensive service.In actual network structure, the position of each node, resource are simultaneously It is not exactly the same, it can be understood as with different levels network structure, the node of high-level can be understood as the gateway in real network ISP (Internet Service Provider, the Internet Service Provider) section that node or low-level nodes connect jointly Point.Entire scene the following steps are included:

Step 101: content consumer 03 (terminal) is participating in real time business (such as network direct broadcasting), is still in position 1, and Data (constantly sending interest packet to the node) is obtained from 1 node 01 of layer currently connected, is forwarded to the outside multicast of the node Interest packet reaches contents producer 04, is matched to corresponding data packet, and the return of data packet hop-by-hop reaches content consumer 03.

Step 102: content consumer 03 starts to move, before not completing all data having requested that of reception, wireless signal Intensity reaches lower threshold, and content consumer 03 is disconnected the connection of the front nodal point of sum.

Step 103: content consumer 03 is moved to position 2 and new 1 node 01 of layer establishes connection, completes switching.

Step 104: content consumer 03 sends interest packet to new 1 node 01 of layer, including does not receive data packet before and return Multiple interest packet and the interest packet newly requested, are restored to normal condition identical with step 101.

Due to contents producer 04 with content consumer 03 apart from remote and closer apart from content consumer 03 in network Repeating transmission interest packet will cause obviously after not having the data packet copy of live broadcast service, content consumer 03 to be connected to new node at node Time delay, influence consumer experience.

The embodiment of the invention provides a kind of based on active cache and the mobile support policy of the terminal of time prediction, and will put down It is multilevel structure that the cache node structure in face, which is expanded, when terminal request data, in the case where node switching occurs, when reduction Prolong and cache expense, minimizes mobile cost.Specifically, the embodiment of the present invention, which is directed to terminal, has issued interest packet, but The scene of node switching just occurs before the reception for completing corresponding data packet.

Referring to fig. 2, Fig. 2 is the data transmission method based on active cache in the name data network of the embodiment of the present invention, Flow diagram applied to terminal, comprising:

S201 obtains the first strength time sequence of the first signal strength and time formation when terminal starts mobile, and The first rate time series that first transmission rate and time are formed, wherein the first signal strength be terminal and first node it Between the signal strength that connects, the first transmission rate transmits the rate of data between terminal and first node, and first node is eventually The node connected before end node switching.

It in name data network, is communicatively coupled between terminal and first node, when terminal is communicated to first node When the edge of covering is mobile, the signal strength connected between terminal and first node starts to weaken, corresponding terminal and first segment Transmission rate between point also reduces simultaneously.

The corresponding relationship for obtaining the first signal strength and time obtains the first transmission speed as the first strength time sequence The corresponding relationship of rate and time, as first rate time series.

S202 determines the switching time started that terminal and first node disconnect according to the first strength time sequence.

According to the first strength time sequence, application time sequential forecasting models, prediction switching time started.Actual conditions In, signal strength will appear shake, interference signal, therefore can carry out wavelet transformation first, then carry out sequence prediction.Time herein Sequence Description model is the arbitrary model for meeting the embodiment of the present invention.Time series preset model includes: autoregression model, index Smoothing model and ash box prediction.

S203 determines that terminal has requested that according to switching time started and first rate time series, but opens in node switching It was unable to complete before beginning received to cache contents.

According to first rate time series, application time sequential forecasting models, the change of the first transmission rate of prediction at any time Change.It is changed with time according to switching time started and the first transmission rate of prediction, before determining node switching, terminal can be from Received data capacity at first node.And then determine terminal have requested that, but node switching start before be unable to complete it is received Content.

S204 sends first interest packet of the mark to cache contents to first node, so that first node receives and basis First interest packet will be cached in the corresponding Node subsets of first node to cache contents.

By the mark of the name to cache contents in the first interest packet, and the first interest Bao Zhi is sent before connection disconnects One node.

S205 is sent to second node for requesting the to cache contents after terminal switching is connected to second node Two interest packets.

After the completion of node switching, terminal sends the second interest packet to second node, to request to cache contents.Second interest The form of packet is the common version in existing NDN.

S206, receives by second node according to the second interest packet, obtains from the corresponding Node subsets of first node concurrent Send to cache contents.

Certainly, terminal can also send other interest packets in addition to the first interest packet and the second interest packet to second node, To request the other content in addition to cache contents, details are not described herein again.

In embodiments of the present invention, terminal receives data to disconnection is connected, and middle terminal stops in advance compared with the prior art Data are received, reduces the time delay that data are transmitted in node handoff procedure, has saved Internet resources.In addition, terminal is to network-side First interest packet of the mark to cache contents is sent, network-side is chosen cache contents according to the first data packet, can be effectively prevent The loss of data in handoff procedure.

Optionally, first interest packet of the mark to cache contents is sent to first node, comprising:

Step 1, obtains mobile terminal just in the data capacity of received data packet, as a comparison capacity.

Step 2 is greater than to specific capacity, node switch before terminal can also from first node received data capacity When, mark is sent to cache contents and the first interest packet of mark switching time started to first node, wherein when switching starts Between time for being disconnected for terminal and first node.

Being less than data-quantity threshold to specific capacity, (terminal received data can also be held from first node before node switches Amount), terminal is indicated before disconnecting with first node, can complete the reception just in received data packet, and terminal is completed Then the reception of the data packet judges next data packet.Data threshold is greater than to specific capacity, indicates terminal and first Before node disconnects, it is unable to complete the reception just in received data packet, terminal sends the first interest packet to first node. Compared to the interest packet in existing NDN, the first interest packet is added to mobile messaging, and the first interest packet identify it is to be cached to slow Deposit content.Optionally, the first interest packet is as shown in table 1:

Table 1

Content Name
	Selector
Nonce
	Handover information

Wherein, Content Name is used to identify to cache contents (name of the record to cache contents), Handover Information is for identifying the switching time started.

The Selector in Selector and Nonce and prior art interest packet in first interest packet is identical as Nonce, For auxiliary route and repeating process.

In embodiments of the present invention, the concrete methods of realizing that terminal sends the first interest packet is given, small to specific capacity The first interest packet is sent when data-quantity threshold, what is identified in the first interest packet is more quasi- to cache contents and switching time started Really, this is because the first strength time sequence and first rate time series that terminal obtains are longer, prediction result is more accurate, and The time of prediction, prediction result was more accurate closer to current time.Network-side carries out the caching of data according to the first interest packet, When cache contents and more accurate switching time started, the cache resources that network-side occupies are fewer, saved Internet resources.

The of subsequent time period is predicted by preset time series predicting model according to the first strength time sequence The sequence that one signal strength and time are formed, and determine the switching time started.According to first rate time series, by preset Time series predicting model, the sequence that the first transmission rate and time for predicting subsequent time period are formed, and determine data volume Threshold value.Time series preset model described herein is the arbitrary model for meeting the embodiment of the present invention, such as exponential smoothing model, ash Box prediction, common autoregression model, linear autoregressive models, hyperbolic function autoregression model and exponential function autoregression mould Type, details are not described herein again.

Optionally, according to the first strength time sequence, the switching time started that terminal and first node disconnect is determined, Include:

Step 1 determines the second strength time sequence by autoregression model according to the first strength time sequence.

The signal strength that terminal is connect with first node when t moment in second strength time sequence is

Autoregression model described herein is common autoregression model.It certainly, herein can also be according to other times sequence Column preset model, such as exponential smoothing model, ash box prediction, hyperbolic function autoregression model or exponential function autoregression model, Determine the switching time started, details are not described herein again.

Step 2 determines third strength time sequence by linear autoregressive models according to the second strength time sequence.

The signal strength that terminal is connect with first node when t moment in third strength time sequence is

The 4th strength time sequence is calculated according to the second strength time sequence and third strength time sequence in step 3 Column.

According toDetermine the 4th intensity time series, whereinFor the 4th strength time Sequence, a_tFor modeling parameters, andb_tFor modeling parameters, andM is positive integer, T₁To determine the second strength time sequence by autoregression model When, the quantity for the numerical value chosen from the first strength time sequence.

Step 4, when the signal strength indication and four intensity that are connect according to preset terminal with first node when disconnecting Between sequence, determine switching the time started.

Obtain signal strength indication X when preset terminal connect disconnection with first node_threshold, according toDetermine the switching time started.

When the signal strength of prediction be reduced to connection disconnect when signal strength indication when, node switching start, at this time when Between be switching the time started.

In embodiments of the present invention, the circular for determining the switching time started is given, according to autoregression model And linear autoregressive models predict the 4th intensity time series, so that it is determined that the switching time started, than autoregression mould is used alone Type or linear autoregressive models, the predicted value for switching the time started are more accurate.

Optionally, in the name data network of the embodiment of the present invention in the data transmission method based on active cache, root It according to switching time started and first rate time series, determines that terminal has requested that, but is unable to complete and connects before node switching starts Receive to cache contents, comprising:

Step 1 determines the second rate time sequence by autoregression model according to first rate time series.

In second rate time sequence, transmission rate when t moment between terminal and first node is

Step 2 determines third speed time series by linear autoregressive models according to the second rate time sequence.

In third speed time series, transmission rate when t moment between terminal and first node is

Fourth rate time sequence is calculated according to the second rate time sequence and third speed time series in step 3 Column.

According toDetermine fourth rate time series, whereinFor the fourth rate time Sequence, c_tFor modeling parameters, andd_tFor modeling parameters, andM is positive integer.T₂To determine the second rate time sequence by autoregression model When, the quantity for the numerical value chosen from first rate time series.

Step 4 determines data-quantity threshold according to switching time started and fourth rate time series.

According toDetermine data-quantity threshold, whereinFor data volume threshold Value, T_ΔFor each message transmission rate corresponding unit time, n indicates that the current time distance switching time started also needs by n A unit time.

Step 5 obtains the data capacity for the data packet being currently being received, in the number for the data packet being currently being received When being greater than data-quantity threshold according to capacity, terminal being had requested that, received content still, which has not been completed, is determined as to cache contents.

In embodiments of the present invention, the specific method determined to cache contents is given, according to autoregression model and linearly Autoregressive model prediction fourth rate time series, so that it is determined that cache contents, than autoregression model or linear is used alone Autoregression model, what is determined is more accurate to cache contents.

The present invention is specifically described application scenarios first, the first interest packet, switching time started has then been determined and to slow Deposit content.The implementation process of network-side will be illustrated below.The movement of real-time monitoring terminal in NDN of the embodiment of the present invention State determines the Node subsets for carrying out active cache, and dynamic updates, while considering time delay and caching expense, and by plane Buffer structure is improved to multi-level buffer structure, is further reduced mobile cost.

It is the data transmission method based on active cache in the name data network of the embodiment of the present invention referring to Fig. 3, Fig. 3, The flow diagram of network-side applied to name data network, comprising:

S301, reception and the first interest packet according to the mark sent by terminal to cache contents determine what needs cached Content be to cache contents, wherein had requested that cache contents for terminal, but node switching start before be unable to complete it is received Content.

First node receives the first interest packet sent by terminal, and the first interest packet mark needs to cache interior wait cache Hold, the switching time started that certain first interest packet can also identify terminal and first node disconnects.

S302, obtains and according to the signal intelligence of entire name data network, determines the corresponding Node subsets of first node, Wherein, first node is by the preceding node connected of terminal node switching

According to the historical record of the signal intelligence of name data network, the node that may be switched to of terminal is chosen, as the The corresponding Node subsets of one node.

S303 is cached according to the first interest packet to cache contents into the corresponding Node subsets of first node, so that second Node is used to request the second interest packet to cache contents according to what is sent by terminal, in the corresponding Node subsets of first node In, it obtains and sends to cache contents, so that terminal is received to cache contents, wherein second node is after terminal node switches The node connected.

Terminal completes node switching, establishes connection with new node (second node), terminal sends second to second node Interest packet.Second node according to the second interest packet, obtained in the corresponding Node subsets of first node caching to cache contents, And it sends to terminal to cache contents.

In embodiments of the present invention, network-side determines the corresponding Node subsets of first node, and will cache to cache contents To in the corresponding Node subsets of first node, when terminal is requested when cache contents to second node, second node is from first It obtains in the corresponding Node subsets of node to cache contents, and is sent to terminal, reduce data in node handoff procedure and transmit Time delay.

Optionally, it according to the first interest packet, caches when cache contents are into first node corresponding Node subsets, when When reaching preset caching stop condition, stop caching to cache contents.

If handoff procedure is longer, i.e., terminal is longer in the time disconnected, the corresponding Node subsets of first node A large amount of contents may be cached, to waste cache resources, it is therefore desirable to setting caching stop condition.Cache stop condition packet Include: the data capacity to cache contents of caching reaches buffer memory capacity threshold value C_pre, to cache contents all caching complete and node Finishing switching (terminal is connected to new node).

In embodiments of the present invention, caching stop condition is given, the waste of cache resources is effectively prevented, has saved net Network resource.

When terminal starts movement and switches start node, specific information will be sent to current connected first node (the first interest packet), informing network end switch the time started and to cache contents.Network-side is switched to first node according to terminal Neighbor node transition probability, select the corresponding Node subsets active cache of first node to wait for cache contents, so that terminal is complete After being connected to second node at node switching, directly acquire to cache contents.It in embodiments of the present invention, can be directly by terminal The node that may be switched to all is added in the corresponding Node subsets of first node, the section that can also may be switched to from terminal At least one node is chosen in point as the corresponding Node subsets of first node.

Optionally, it receives and the first interest packet according to the mark sent by terminal to cache contents, determination needs to cache Content be to cache contents, comprising:

Step 1, what reception was sent by terminal, the first interest packet to cache contents and mark switching time started is identified, Wherein, the switching time started is terminal and the time that first node disconnects.

Step 2, according to the switching time started in the first interest packet, determination starts to cache the time to cache contents.

Network-side can formulate the time that caching starts according to the switching time started.Such as the switching time started is established as delaying It deposits the time of beginning, or was set as the time that caching starts for first 0.1 second that switches the time started.

Step 3, according to, to cache contents, the content that determining needs cache is to cache contents in the first interest packet.

In embodiments of the present invention, the first interest packet identifies simultaneously starts to cache contents and mark switching, according to first Interest packet determines when which kind of content cached, and the message that terminal transmission is received compared to one begins to be cached, and shortens slow The time for depositing occupancy can reduce caching cost, save Internet resources.

Optionally, it obtains and according to the signal intelligence of entire name data network, determines corresponding node of first node Collection, comprising:

After step 1, acquisition terminal and first node disconnect, each node in terminal and network-side establishes connection Transition probability, wherein first node is by the node that connects before terminal node switching.

It can determine terminal from the node connected at present the analysis of terminal behavior (such as: mobile trajectory data) according in NDN It is moved to the transition probability of other nodes.Obtaining the method for transition probability herein is to meet any means of the embodiment of the present invention, The method for calculating transition probability in the prior art is suitable for the embodiment of the present invention.Such as:

Terminal is completed once from node r_iTo node r_jSwitching after, to r_jSend r_iMark.According to the mark, r_jTo r_i It sends message informing this time to shift, establishes e=(r_i,r_j).Each node respectively collection terminal from itself being switched to other nodes Number, r_iThe related data of middle storage is expressed as Transition (r_i)={ (r_j,n_ij)|r_j∈V,(r_i,r_j) ∈ e, wherein Transition(r_i) it is that node switches storage function, V is the set for naming all nodes in data network, n_ijIt is terminal from r_i It is switched to r_jNumber.Handover(r_i) it is eventually It holds from r_iIt is switched to the total degree of other nodes.Often receive the message of primary notice transfer, r_iMiddle Handover (r_i) increase by 1. If receiving from non-acquisition node r_xTransfer Message, in Transition (r_i) one new element (r of middle addition_x,n_ix=1), Handover(r_i) value increase by 1.Terminal is from r_iIt is transferred to r_jTransition probability be P_ij=n_ij/Handover(r_i)。

With the accumulation of terminal node switching behavior, change, the transition probability from a node to another node can move State updates.When network just brings into operation, the node that node switching occurs is collected not yet, not about transfer in each node The related data of probability, therefore do not have that node is selected to carry out active cache, network is to ambulant support and primary at this time NDN is identical.With the acquisition of data, processing, the judgement of transition probability can tend to be accurate and stablize, and choose Node subsets accordingly The scheme for carrying out active cache will gradually come into force.In addition, the calculating due to transition probability comes from and a large amount of historical datas, low frequency Wrong data (for example user has actively closed network, shutdown, it is mobile it is far after just access again) influence to result can be with Ignore.

Step 2 obtains the data delay that terminal obtains data from each node in network respectively.

Step 3, obtain and according to the caching situation of each node in network, respectively determine network in each node Caching cost.

Total spatial cache of node j isThe space occupied isThen the caching cost of node j isμ^jFor the Buffer Utilization of j node, and

Step 4 determines the corresponding Node subsets of first node according to transition probability, data delay and caching cost.

In embodiments of the present invention, give the method for the corresponding Node subsets of determining first node, it is contemplated that caching at This, reduces the expense of caching, has saved Internet resources.

Optionally, according to transition probability, data delay and caching cost, the corresponding Node subsets of first node is determined, are wrapped It includes:

According toDetermine time delay totle drilling cost, In, L_totalFor time delay totle drilling cost, P_ijFor the probability that the terminal in transition probability is connect with j node,For in data delay Terminal obtains the time delay of data from j node,L_missIt is the terminal in data delay to cache contents The producer obtain data time delay, j node be the corresponding Node subsets of first node in node.

J ∈ S ' expression j node is the node in the corresponding Node subsets of first node.

According toDetermine caching totle drilling cost, wherein C_totalTo cache totle drilling cost,For J nodal cache in caching cost waits for the cost of cache contents, and j node is the node in the corresponding Node subsets of first node.

According to Cost_total=w_lL_total+w_cC_total, determine overall situation totle drilling cost, wherein Cost_totalFor global totle drilling cost, L_totalFor time delay totle drilling cost, C_totalTo cache totle drilling cost, w_lFor the first default weight, w_cFor the second default weight, and w_lWith w_c? For preset coefficient.

w_lWith w_cIt is set according to the specific signal intelligence of NDN, when cache resources anxiety in NDN, increases w_cNumber Value reduces w_lNumerical value.When cache resources leave unused more in NDN, increase w_lNumerical value, reduce w_cNumerical value.Specifically, can To be set asOr it is smaller,Or it is smaller.

According toJudge to name whether the node in data network belongs to first respectively The corresponding Node subsets of node, ifThen node k belongs to the corresponding node of first node Subset, whereinIndicate global totle drilling cost when the corresponding Node subsets of first node are empty set.

Indicate global totle drilling cost when the corresponding Node subsets of first node are empty set, i.e. terminal is from life Production person locates to obtain the global totle drilling cost to cache contents；Cost_total(k) indicate that the corresponding Node subsets of first node are only saved by k Global totle drilling cost when point is constituted, i.e. terminal obtain the global totle drilling cost to cache contents from k node or the producer.After abbreviation, it may finally indicate are as follows:

In practical NDN, by node setting position influenced, the communication distance between node not necessarily with physical distance Match, therefore after node switching occurs for terminal, the new node of connection and the communication distance of origin node may a more than jumps.Therefore in this hair By neighbor node in bright embodiment is defined as: when terminal carries out minor node switching, node switches latter linked new node and is, saves The neighbor node of the origin node connected before point switching.

In the actual operation process, digraph G=(V, E) is defined, wherein V={ r₁,r₂…,r_nIt is all sections in network The set of point, and the node in V has the name of hierarchical (similar with interest packet).Occurred in a network from r_iTo r_jCut It changes, then claims r_jIt is r_iNeighbor node, with e=(r_i,r_j) indicate, this relationship between all nodes constitutes set E={ e₁, e₂,…,e_i}.Node r_iNeighbor node be expressed as Neighbor (r_i)={ r_j|r_j∈V,(r_i,r_j)∈E}。

Optionally, the corresponding Node subsets of first node are determined, comprising:

Step A obtains the neighbor node set of first node.

Step B obtains a node k in the neighbor node set of first node at random.

Step C, judge k whether satisfactionIf meetingK is added in the corresponding Node subsets of first node, and from first node K is removed in neighbor node set, if being unsatisfactory forDirectly from the neighbor node of first node K is removed in set.

Step D judges whether the neighbor node set of first node is empty set, if the neighbor node set of first node is not It is that empty set return step B is continued to execute, if the neighbor node set of first node is empty set, the corresponding node of output first node Subset.

In embodiments of the present invention, the corresponding Node subsets of first node, phase are determined in the neighbor node of first node Than reducing the complexity of network-side operation, having saved net in choosing the corresponding Node subsets of first node from all nodes Network resource.

Optionally, the corresponding Node subsets of output first node, comprising:

Step E obtains all nodes in the corresponding Node subsets of first node, as to packet node；

Step F determines the father node to packet node respectively, will be to there is the node of identical father node to be divided into packet node Into a grouping, at least one set of grouping to be determined is obtained；

Step G carries out the judgement of father node cost: randomly selecting one group of to be determined point for not carrying out father node cost judgement Group judges the sum of the global totle drilling cost of all nodes in the grouping to be determined chosen, if greater than in the grouping to be determined of selection The global totle drilling cost of the father node of node, if choose grouping to be determined in all nodes global totle drilling cost sum, be greater than select The father node of the grouping interior joint to be determined of selection is added the global totle drilling cost of the father node of the grouping interior joint to be determined taken Into the corresponding Node subsets of first node, and from the grouping to be determined for deleting selection in the corresponding Node subsets of first node Node；

Step H judges whether there are also the groupings for not carrying out father node cost judgement at least one set of grouping to be determined, if at least There is the grouping for not carrying out father node cost judgement in one group of grouping to be determined, return step G is continued to execute, if at least one set is wait sentence Do not have not carry out the grouping of father node cost judgement in fixed grouping, the corresponding Node subsets of output first node.

In embodiments of the present invention, NDN is expanded into secondary structure by planar structure.Reducing terminal node handover delay On the basis of, caching expense is further reduced, Internet resources have been saved.

Certainly in embodiments of the present invention, can according to actual needs, the N-1 E that repeats the above steps is to step H, in turn NDN is extended to N (N is positive integer) level structure.

Referring to fig. 4, Fig. 4 is a kind of flow diagram of method of the Node subsets of the determination node i of the embodiment of the present invention, Include:

S401 determines that the node that terminal occurs to connect before node switching is node i.

S402 obtains the neighbor node set S of node i, wherein the neighbor node of node i is the section adjacent with node i Point.

In embodiments of the present invention, the neighbors of a node refers to that with the node communication distance be a node jumped.

S403, the Node subsets for initializing node i are empty set.

S404 obtains the arbitrary node k in set S.

S405 is judged whether there isIfIt holds Row step S406, ifExecute step S407.

Node k is added in the Node subsets of node i by S406.

S407 removes node k from set S.

S408 judges whether set S is empty set, if set S is that empty set executes step S409, if set S does not hold for empty set Row step S404.

S409 judges whether terminal is static, disconnects the connection with node i or reach buffer memory capacity with the data volume prefetched Threshold value executes step S402, if the Node subsets of output node i if not.

In embodiments of the present invention, the specific method of determining Node subsets is given, for that will store to cache contents to section Idea concentration provides technical support.

Referring to Fig. 5, Fig. 5 is the process signal of another method of the Node subsets of the determination node i of the embodiment of the present invention Figure, comprising:

S501 determines that the node that terminal occurs to connect before node switching is node i.

S502 obtains the neighbor node set S of node i, wherein the neighbor node of node i is the section adjacent with node i Point.

S503, the Node subsets for initializing node i are empty set.

S504 obtains the arbitrary node k in set S.

S505 judges whether to meet 1 decision condition of layer:If there is execution step S506, if without step S507 is executed.

Node k is added in the Node subsets of node i by S506.

S507 removes node k from set S.

S508 judges whether set S is empty set, if executing step S509, executes step S504 if not.

S509 chooses in the Node subsets of node i, there is the node of identical father node.

Referring to Fig. 6, Fig. 6 is the schematic diagram of the tertiary structure network of the embodiment of the present invention, and each node of layer 1 is in layer 2 1 node under, i.e., corresponding 1 father node of multiple child nodes, each node of layer 2 are under layer 3.

The father node duplicate removal set of the Node subsets S ' of node i is represented with ▽ S '.By taking Fig. 6 as an example, if S '={ w, e, r }, Then ▽ S '={ u, v }.S ' is enabled to be split as by each father node | ▽ S ' | a subset S '_i, | ▽ S ' | it is the number of elements in ▽ S ', i.e., Father node number, there is S '₁={ q, w }, S '₂={ e, r, t, y }.

S510 judges to meet 1 decision condition of layer:

If holding Row step S511, thens follow the steps S512 if not.

Terminal is expressed as from the time delay cost that a 2 node j of layer obtains a content itemNodal cache is accordingly interior Hold item caching cost beThe node k of corresponding layer 1,WithBecome forWith

If being prefetched to each S '_i(i=1,2 ..., | ▽ S ' |) totle drilling cost be greater than and be prefetched to the cost of its father node, then its Father node replaces the S_i′.The discriminate that 2 node m of layer are selected in S ' is as follows:

S511 deletes the node for having identical father node from the Node subsets of node i, its father node is added.

S512, it is determined whether there are also the nodes not judged, if executing step S509, then follow the steps S513 if not.

S513 judges whether terminal is static, disconnects the connection with node i or reach buffer memory capacity with the data volume prefetched Threshold value executes step S502, if the Node subsets of output node i if not.

Certainly, on the basis of above-mentioned secondary structure, executing S501 to S513 again can be extended NDN by secondary structure To tertiary structure, and then it is extended to N (N is the positive integer greater than 3) level structure.In the NDN of reality, the grade of practical application structure Number can be according to signal intelligence sets itself, when cache resources anxiety in NDN, and the series setting of structure is larger.When being cached in NDN When resources idle is more, the series setting of structure is smaller.Specifically, can be level-one (planar structure) or more by structure setting Greatly, second level or bigger.

Planar structure (primary structure) in the embodiment of the present invention, which refers to, only considers that the node at the edge NDN (only considers layer 1 In node), do not consider the father node of any node.Secondary structure refers to other than considering 1 node of layer, it is also necessary to consider layer 1 In node father node (node in layer 2).N level structure refers to the whole nodes for considering that layer 1 arrives layer N.

Referring to Fig. 6, in embodiments of the present invention by taking three-level meshed network as an example, illustrate to select in its layer 1 and 2 node of layer Prefetch the partial routine of Node subsets.It is calculated to simplify, it is assumed that each node has identical caching cost in the structure C_cache, node requests data from terminal to layer 1 time delay costTime delay cost to the node requests data of layer 2 isAnd w_c/w_l=0.5.If 1 node of given layer is the neighbor node of terminal present node i.Known terminal is moved to 1 node set S=of layer after starting switching Transition probability in { q, w, e, r, t, y } is { P_ik(k∈s)}={ 0.2,0.4,0.1,0.05,0.1,0.15 }, then present node i Node subsets selection strategy it is as follows:

Step 1: the node i that terminal is currently connected to is obtained, its neighbor node set S={ q, w, e, r, t, }, y are obtained Initialize the Node subsets of node i

Step 2: a node is arbitrarily selected in S, it is assumed that be q.

Step 3: judgement

Step 4: node q is selected into the Node subsets of node i, i.e. S '={ q }.

Step 5: node q, i.e. S={ w, e, r, t, y } are removed from set S.

Step 6: there are also nodes in judgement set S, repeat S404 to S408, untilObtain S '=q, w}。

Step 7: the Node subsets that selects from layer 1 of processing obtain ▽ S '={ u }, | ▽ S ' |=1, then S ' only one divide Group S '={ q, w }, takes 2 node u of layer；

Step 8:

Step 9: 2 node u of layer is not selected, and the Node subsets of active cache are S '={ q, w }.Do not judge Node.

Step 10: terminal has disconnected the connection with node i.

Step 11: algorithm terminates.

In embodiments of the present invention, the practical determining process of secondary structure interior joint subset is given, for will be wait in caching It stores storage and provides technical support into Node subsets.

It should be noted that the system in the embodiment of the present invention is applied in above-mentioned name data network based on active cache Data transmission method system, then in above-mentioned name data network the data transmission method based on active cache all implementations Example is suitable for the system, and can reach the same or similar beneficial effect.

Referring to Fig. 7, Fig. 7 is that the data transmission system based on active cache is answered in the name data network of the embodiment of the present invention Schematic diagram for terminal, comprising:

Time series obtains module 701, for when terminal starts mobile, obtaining what the first signal strength was formed with the time The first rate time series that first strength time sequence and the first transmission rate and time are formed, wherein the first signal strength The signal strength connected between terminal and first node, the first transmission rate transmit data between terminal and first node Rate, first node is by the preceding node connected of terminal node switching.

Time started computing module 702, for determining that terminal and first node disconnect and connecting according to the first strength time sequence The switching time started connect.

To cache contents determining module 703, for determining terminal according to switching time started and first rate time series Have requested that, but node switching start before be unable to complete it is received to cache contents；

First interest packet sending module 704, for sending first interest packet of the mark to cache contents to first node, with Make first node receive and according to the first interest packet, will be cached to cache contents in the corresponding Node subsets of first node.

Second interest packet sending module 705, for sending and using to second node after terminal switching is connected to second node In second interest packet of the request to cache contents.

It is corresponding from first node for receiving by second node according to the second interest packet to cache contents receiving module 706 Node subsets in obtain and send to cache contents.

Optionally, time started computing module 702, comprising:

Second strength time sequence computational submodule is used for according to the first strength time sequence, true by autoregression model Fixed second strength time sequence.

Third strength time sequence computational submodule, for passing through linear autoregression mould according to the second strength time sequence Type determines third strength time sequence.

4th intensity time series computational submodule, for according to the second strength time sequence and third strength time sequence Column, are calculated the 4th intensity time series.

The switching time started determines submodule, the letter for being connect according to preset terminal with first node when disconnecting Number intensity value and the 4th intensity time series determine the switching time started.

Referring to Fig. 8, Fig. 8 is that the data transmission system based on active cache is answered in the name data network of the embodiment of the present invention Schematic diagram for network-side, comprising:

Interest packet receiving module 801, the first interest for receiving and according to the mark sent by terminal to cache contents Packet determines that needing the content cached is to cache contents, wherein have requested that cache contents for terminal, but open in node switching Received content was unable to complete before beginning.

Node subsets determining module 802 determines first for obtaining and according to the signal intelligence of entire name data network The corresponding Node subsets of node, wherein first node is by the preceding node connected of terminal node switching.

Cache module 803, for caching to cache contents to the corresponding Node subsets of first node according to the first interest packet In, so that second node is used to request the second interest packet to cache contents according to what is sent by terminal, it is corresponding in first node Node subsets in, obtain and send to cache contents so that terminal receive to cache contents, wherein second node is terminal The node connected after node switching.

It should be noted that the data transmission system based on active cache is answered in the name data network of the embodiment of the present invention For network-side, then each node also has other than caching, forwarding data grouping and receives mobile message, calculated, select to save The function of point subset.Certainly in actual deployment, it can use additional server also to realize some or all of above-mentioned function Can, details are not described herein again.

Optionally, Node subsets determining module 802, comprising:

Transition probability acquisition submodule, for obtaining terminal and after first node disconnects, in terminal and network-side Each node establishes the transition probability of connection, wherein first node is by the preceding node connected of terminal node switching.

Data delay acquisition submodule, when for obtaining data of the terminal from each node acquisition data in network respectively Prolong.

Caching cost acquisition submodule determines respectively for obtaining and according to the caching situation of each node in network The caching cost of each node in network.

Node subsets choose submodule, according to transition probability, data delay and caching cost, determine that first node is corresponding Node subsets.

Optionally, Node subsets choose submodule, comprising:

Time delay totle drilling cost computing unit is used for basis

Determine time delay totle drilling cost, wherein L_totalFor time delay totle drilling cost, P_ijFor the probability that the terminal in transition probability is connect with j node,For the end in data delay The time delay that data are obtained from j node is held,L_missIt is the terminal in data delay to cache contents The producer obtains the time delay of data, and j node is the node in the corresponding Node subsets of first node.

Totle drilling cost computing unit is cached, basis is used forDetermine caching totle drilling cost, wherein C_totalTo cache totle drilling cost,The cost of cache contents is waited for for the j nodal cache in caching cost, j node is first segment Node in the corresponding Node subsets of point.

Global totle drilling cost computing unit, for according to Cost_total=w_lL_total+w_cC_total, determine overall situation totle drilling cost, In, Cost_totalFor global totle drilling cost, L_totalFor time delay totle drilling cost, C_totalTo cache totle drilling cost, w_lFor the first default weight, w_c For the second default weight, and w_lWith w_cIt is preset coefficient.

Comparing unit is calculated, basis is used forRespectively in judgement name data network Node whether belong to the corresponding Node subsets of first node, ifThen node k belongs to The corresponding Node subsets of first node, whereinIndicate that the corresponding Node subsets of first node are empty set.

Optionally, comparing unit is calculated, comprising:

Neighbor node obtains subelement, for obtaining the neighbor node set of first node.

Node randomly chooses subelement, the node k in neighbor node set for obtaining first node at random.

Node selection and exclude subelement, for judge k whether satisfactionIf full FootK is added in the corresponding Node subsets of first node, and from first node K is removed in neighbor node set, if being unsatisfactory forDirectly from the neighbor node of first node K is removed in set.

First output subelement, for judging whether the neighbor node set of first node is empty set, if first node Neighbor node set is not that empty set return node random selection subelement continues to execute, if the neighbor node set of first node is Empty set, the corresponding Node subsets of output first node.

Optionally, the first output subelement, is further used for:

Step E obtains all nodes in the corresponding Node subsets of first node, as to packet node.

Step F determines the father node to packet node respectively, will be to there is the node of identical father node to be divided into packet node Into a grouping, at least one set of grouping to be determined is obtained.

Step G carries out the judgement of father node cost: randomly selecting one group of to be determined point for not carrying out father node cost judgement Group judges the sum of the global totle drilling cost of all nodes in the grouping to be determined chosen, if greater than in the grouping to be determined of selection The global totle drilling cost of the father node of node, if choose grouping to be determined in all nodes global totle drilling cost sum, be greater than select The father node of the grouping interior joint to be determined of selection is added the global totle drilling cost of the father node of the grouping interior joint to be determined taken Into the corresponding Node subsets of first node, and from the grouping to be determined for deleting selection in the corresponding Node subsets of first node Node.

Optionally, interest packet receiving module 801, comprising:

First interest packet acquisition submodule, for receiving by terminal transmission, mark is opened to cache contents and mark switching The first interest packet of time beginning, wherein the switching time started is terminal and the time that first node disconnects.

Cache-time determines submodule, for according to the switching time started in the first interest packet, determine start caching to The time of cache contents.

Cache contents determine submodule, for according to, to cache contents, determining needs cache interior in the first interest packet Hold for cache contents.

It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to Non-exclusive inclusion, so that the process, method, article or equipment including a series of elements is not only wanted including those Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or equipment Intrinsic element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that There is also other identical elements in process, method, article or equipment including the element.

Each embodiment in this specification is all made of relevant mode and describes, same and similar portion between each embodiment Dividing may refer to each other, and each embodiment focuses on the differences from other embodiments.Especially for system reality For applying example, since it is substantially similar to the method embodiment, so being described relatively simple, related place is referring to embodiment of the method Part explanation.

The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the scope of the present invention.It is all Any modification, equivalent replacement, improvement and so within the spirit and principles in the present invention, are all contained in protection scope of the present invention It is interior.

Claims

1. the data transmission method based on active cache in a kind of name data network, which is characterized in that be applied to terminal, packet It includes:

When terminal starts mobile, the first strength time sequence and the first transmission of the first signal strength and time formation are obtained The first rate time series that rate and time are formed, wherein first signal strength be the terminal and first node it Between the signal strength that connects, first transmission rate transmits the rate of data between the terminal and the first node, The first node is by the preceding node connected of terminal switching；

According to the first strength time sequence, when the switching for determining that the terminal and the first node disconnect starts Between；

According to the switching time started and the first rate time series, determine that the terminal has requested that, but cut in node Change beginning before be unable to complete it is received to cache contents；

The mark first interest packet to cache contents is sent to the first node, so that the first node receives and root According to the first interest packet, it is cached to described in the corresponding Node subsets of the first node to cache contents；

After terminal switching is connected to second node, Xiang Suoshu second node sends described to cache contents for requesting Second interest packet；

It receives by the second node according to the second interest packet, is obtained simultaneously from the corresponding Node subsets of the first node What is sent is described to cache contents.

2. determining institute the method according to claim 1, wherein described according to the first strength time sequence State the switching time started that terminal is disconnected with the first node, comprising:

According to the first strength time sequence, the second strength time sequence is determined by autoregression model；

According to the second strength time sequence, third strength time sequence is determined by linear autoregressive models；

According to the second strength time sequence and the third strength time sequence, the 4th intensity time series is calculated；

Signal strength indication and the 4th strength time when being disconnected according to the preset terminal and the first node Sequence determines the switching time started.

3. the data transmission method based on active cache in a kind of name data network, which is characterized in that be applied to network-side, packet It includes:

The first interest packet simultaneously according to the mark sent by terminal to cache contents is received, determines that it is described for needing the content cached To cache contents, wherein it is described to be had requested that cache contents for the terminal, but reception is unable to complete before node switching starts Content；

It obtains and according to the signal intelligence of entire name data network, determines the corresponding Node subsets of first node, wherein described First node is by the preceding node connected of terminal switching；

According to the first interest packet, caching it is described to cache contents into the corresponding Node subsets of the first node so that Second node is used to request the second interest packet to cache contents according to what is sent by the terminal, corresponding in the first node Node subsets in, obtain and send it is described to cache contents so that the terminal receive it is described to cache contents, wherein institute State the node connected after second node is switched by the terminal.

4. according to the method described in claim 3, it is characterized in that, described obtain and according to the communication of entire name data network Situation determines the corresponding Node subsets of first node, comprising:

It obtains the terminal and after the first node disconnects, each node in the terminal and network-side establishes connection Transition probability, wherein the first node is by the node that connects before terminal switching；

The data delay that the terminal obtains data from each node in the network-side is obtained respectively；

Obtain and according to the caching situation of each node in the network-side, determine each node in the network-side respectively Caching cost；

According to the transition probability, the data delay and the caching cost, corresponding node of the first node is determined Collection.

5. according to the method described in claim 4, it is characterized in that, it is described according to the transition probability, the data delay and The caching cost determines the corresponding Node subsets of the first node, comprising:

According toDetermine time delay totle drilling cost, wherein The L_totalFor the time delay totle drilling cost, the P_ijJ node is transferred to from i-node for the terminal in the transition probability Probability, it is describedThe time delay of data is obtained from j node for the terminal in the data delay, it is describedThe L_missNumber is obtained from the producer to cache contents for the terminal in the data delay According to time delay, the j node be the corresponding Node subsets of the first node in node, the S ' be first node it is corresponding Node subsets；

According toDetermine caching totle drilling cost, wherein the C_totalIt is described for the caching totle drilling costFor the cost described in the j nodal cache in the caching cost to cache contents, the j node is the first node Node in corresponding Node subsets；

According to Cost_total=w_lL_total+w_cC_total, determine overall situation totle drilling cost, wherein the Cost_totalFor the global assembly This, the L_totalFor the time delay totle drilling cost, the C_totalFor the caching totle drilling cost, the w_lFor the first default weight, institute State w_cFor the second default weight, and the w_lWith the w_cIt is preset coefficient；

According toJudge to name whether the node in data network belongs to described first respectively The corresponding Node subsets of node, ifThen it is corresponding to belong to the first node by node k Node subsets, wherein describedIndicate global assembly when the corresponding Node subsets of the first node are empty set This.

6. according to the method described in claim 5, it is characterized in that, the corresponding Node subsets of the determination first node, Include:

Step A obtains the neighbor node set of the first node；

Step B obtains a node k in the neighbor node set of the first node at random；

Step C, judges whether the k meetsIf meetingThe k is added in the corresponding Node subsets of the first node, and from described The k is removed in the neighbor node set of first node, if being unsatisfactory forDirectly from described The k is removed in the neighbor node set of first node；

Step D judges whether the neighbor node set of the first node is empty set, if the neighbor node collection of the first node Conjunction is not that empty set return step B is continued to execute, if the neighbor node set of the first node is empty set, exports the first segment The corresponding Node subsets of point.

7. according to the method described in claim 6, it is characterized in that, the corresponding Node subsets of the output first node, Include:

Step E obtains all nodes in the corresponding Node subsets of the first node, as to packet node；

Step F determines the father node to packet node, by described to there is the node of identical father node in packet node respectively It is divided into a grouping, obtains at least one set of grouping to be determined；

Step G carries out the judgement of father node cost: randomly selecting one group of grouping to be determined for not carrying out father node cost judgement, sentence The sum of the global totle drilling cost of all nodes in the disconnected grouping to be determined chosen, if greater than being saved in the grouping to be determined of the selection Point father node global totle drilling cost, if in the grouping to be determined of the selection the global totle drilling cost of all nodes sum, be greater than The global totle drilling cost of the father node of the grouping interior joint to be determined of the selection, by the grouping interior joint to be determined of the selection Father node is added in the corresponding Node subsets of the first node, and is deleted from the corresponding Node subsets of the first node The grouping interior joint to be determined of the selection；

Step H, judging at least one set grouping to be determined, whether there are also the groupings for not carrying out the father node cost judgement, if Having in at least one set grouping to be determined and does not carry out the grouping that the father node cost determines, return step G is continued to execute, if Do not have not carry out the grouping that the father node cost determines in at least one set grouping to be determined, exports the first node pair The Node subsets answered.

8. according to the method described in claim 3, it is characterized in that, described receive and identified according to what is sent by terminal wait cache First interest packet of content determines that needing the content cached is described to cache contents, comprising:

What reception was sent by the terminal, the mark first interest packet for switching the time started to cache contents and mark, In, the switching time started is the terminal and the time that the first node disconnects；

According to the switching time started in the first interest packet, determines and start the caching time to cache contents；

It is described to cache contents according to the content for cache contents, determining that needs cache in the first interest packet.

9. the data transmission system based on active cache in a kind of name data network, which is characterized in that be applied to terminal, packet It includes:

Time series obtains module, the last the first for when terminal starts mobile, obtaining the first signal strength and the time is formed Spend time series and the first transmission rate and first rate time series that the time is formed, wherein first signal strength is The signal strength connected between the terminal and first node, first transmission rate are the terminal and the first node Between transmit the rates of data, the first node is for the preceding node connected of terminal switching；

Time started computing module, for determining the terminal and the first node according to the first strength time sequence The switching time started disconnected；

To cache contents determining module, for determining institute according to the switching time started and the first rate time series Terminal is stated to have requested that, but node switching start before be unable to complete it is received to cache contents；

First interest packet sending module, for sending the mark first interest packet to cache contents to the first node, So that the first node receives and according to the first interest packet, the first node pair is cached to cache contents by described In the Node subsets answered；

Second interest packet sending module, for after terminal switching is connected to second node, Xiang Suoshu second node to be sent For requesting the second interest packet to cache contents；

To cache contents receiving module, for receiving by the second node according to the second interest packet, from the first segment It obtains and sends described to cache contents in the corresponding Node subsets of point.

10. the data transmission system based on active cache in a kind of name data network, which is characterized in that it is applied to network-side, Include:

Interest packet receiving module, the first interest packet for receiving and according to the mark sent by terminal to cache contents, determines The content for needing to cache is described to cache contents, wherein it is described to be had requested that cache contents for the terminal, but cut in node Received content is unable to complete before changing beginning；

Node subsets determining module determines first node pair for obtaining and according to the signal intelligence of entire name data network The Node subsets answered, wherein the first node is by the preceding node connected of terminal switching；

Cache module, for according to the first interest packet, caching to be described to cache contents to the corresponding section of the first node Idea is concentrated, so that second node is used to request the second interest packet to cache contents according to what is sent by the terminal, in institute State in the corresponding Node subsets of first node, obtain and send it is described to cache contents so that the terminal receive it is described to slow Deposit content, wherein the node that the second node connects after being switched by the terminal.