CN110099410A - For facing the DTN distributed caching method and equipment of empty wagons earth mat - Google Patents
For facing the DTN distributed caching method and equipment of empty wagons earth mat Download PDFInfo
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- CN110099410A CN110099410A CN201910451298.0A CN201910451298A CN110099410A CN 110099410 A CN110099410 A CN 110099410A CN 201910451298 A CN201910451298 A CN 201910451298A CN 110099410 A CN110099410 A CN 110099410A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/50—Queue scheduling
- H04L47/62—Queue scheduling characterised by scheduling criteria
- H04L47/625—Queue scheduling characterised by scheduling criteria for service slots or service orders
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/90—Buffering arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/90—Buffering arrangements
- H04L49/9084—Reactions to storage capacity overflow
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/50—Network services
- H04L67/56—Provisioning of proxy services
- H04L67/568—Storing data temporarily at an intermediate stage, e.g. caching
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/0284—Traffic management, e.g. flow control or congestion control detecting congestion or overload during communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/0289—Congestion control
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Abstract
The embodiment of the present invention provides a kind of for facing the DTN distributed caching method and equipment of empty wagons earth mat, and this method includes whether detection first node occurs congestion information；If occurring, according to preset rules in the mean exposure frequency meter of the first node, the second node that current time and the first node are in contact is searched；It forwards intensity to select forwarding information according to the message of message each in the first node, and the forwarding information is sent to the second node, so that the forwarding message is sent to destination node by the second node.The embodiment of the present invention can alleviate network node congestion, realize the normal transmission of data；Neighbor node can be communicated by making full use of in network, dispersed the pressure of congested node, increased network utilization；The transmission success rate for improving message, reduces the mean transit delay of message.
Description
Technical field
The present embodiments relate to Data cache technology field more particularly to a kind of DTN distributions for facing empty wagons earth mat
Formula caching method and equipment.
Background technique
With near space dirigible (aerostatics), unmanned plane and earth moving equipment (such as automobile, train) etc. for node
The abortive haul network that faces be a kind of novel dynamic network, there are the advantages such as region overlay, flexible deployment, become a research in recent years
Hot spot.In facing abortive haul network, due to aerostatics-unmanned plane, unmanned plane-unmanned plane and aerostatics (unmanned plane)-ground moving
The complexity of dynamic and communication channel between node, leads to that network topology is changeable, link frequently interrupts, or even occurs of short duration
Network not connection situation in time, these are all to face the group-net communication of abortive haul network to bring difficulty.Specifically, link down mainly produces
Life is at the contour dynamic node of unmanned plane node and user node.Before encountering next-hop node, what is forwarded disappears node
Breath can have been stored in the caching of this node, but the cache resources of node are limited, when node for a long time can not be with next-hop section
When point meets, stored message can be more than nodal cache, generate congestion, influence the reception of subsequent message.
It in the prior art, can only being known based on Indigenous knowledge or network according to formulation when message congestion occurs for node
The message drop policy of knowledge, the message in node is abandoned, to alleviate congestion situation.
Although message abandons can be serious however, above-mentioned strategy can alleviate the congestion situation of node to a certain extent
The success rate of message transmission is influenced, communication quality is reduced.
Summary of the invention
The embodiment of the present invention provide it is a kind of for facing the DTN distributed caching method and equipment of empty wagons earth mat, with improve disappear
Transmission success rate is ceased, communication quality is improved.
In a first aspect, the embodiment of the present invention provide it is a kind of for facing the DTN distributed caching method of empty wagons earth mat, comprising:
Whether detection first node occurs congestion information；
If occur, according to preset rules in the mean exposure frequency meter of the first node, search current time with
The second node that the first node is in contact；
It forwards intensity to select forwarding information according to the message of message each in the first node, and the forwarding information is sent out
It send to the second node, so that the forwarding message is sent to destination node by the second node.
In a kind of possible design, it is described according to preset rules in the mean exposure frequency meter of the first node,
Before the second node that lookup current time is communicated with the first node, further includes:
Create the mean exposure frequency meter of the first node；The contact frequency table includes the caching of the first node
Capacity information；
Detect whether that there are third nodes and the first node to be in contact；
If it exists, then the history frequency of exposure of first node described in current time Yu third node is obtained；
The mean exposure frequency between the first node and the third node is calculated according to the history frequency of exposure；
And the contact frequency table is updated with the mean exposure frequency.
In a kind of possible design, in the mean exposure frequency meter include be in contact with the first node it is each
Mean exposure frequency between node and the first node, it is described according to preset rules the first node mean exposure
In frequency meter, the second node that current time and the first node are in contact is searched, comprising:
Each mean exposure frequency descending arrangement in the mean exposure frequency meter of the first node is obtained into first list；
According to the sequence of the first list, successively detect whether each node occurs at current time and the first node
Contact, until getting the node for the preset quantity being in contact with the first node；
Using the node of the preset quantity as the second node.
It is described that the selected forwarding of intensity is forwarded according to the message of message each in the first node in a kind of possible design
Information, comprising:
The message for obtaining each message of first node described in current time forwards intensity；
The message forwarding intensity of each message is arranged according to descending；
The capacity summation that each message in first ranking to N ranking is occupied, obtains total capacity；
Judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released；
If it is not, the capacity for then occupying each message in the first ranking to N+1 ranking is summed, total capacity is obtained；
Repeat it is described judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released,
If it is not, the step of then capacity of each message occupancy in the first ranking to N+1 ranking is summed, obtains total capacity, until institute
It states total capacity and presets amount of ram to be released more than or equal to the first node；
If so, using each message in the first current ranking to N+1 ranking as forwarding message.
It is described that the selected forwarding of intensity is forwarded according to the message of message each in the first node in a kind of possible design
Information, and the forwarding information is sent to before the second node, further includes:
Judge whether the buffer memory capacity information of the second node meets preset condition；
It is described to forward intensity to select forwarding information according to the message of message each in the first node, and the forwarding is believed
Breath is sent to the second node, comprising:
If satisfied, then selecting forwarding information according to the second preset rules, and the forwarding information is sent to described second
Node.
In a kind of possible design, the buffer memory capacity information includes the residual caching capacity of the second node and total
Whether the ratio between buffer memory capacity, the buffer memory capacity information for judging the second node meet preset condition, comprising:
Judge whether the ratio is greater than preset threshold；
If more than then the buffer memory capacity information of the second node meets preset condition.
It is described that the selected forwarding of intensity is forwarded according to the message of message each in the first node in a kind of possible design
Information, and the forwarding information is sent to after the second node, further includes:
After the congestion information of the first node is alleviated, judge whether the first node occurs with the second node
Contact；
If so, fetching control signal so that the second node returns the forwarding information to second node transmission
It is back to the first node；
The forwarding information is sent to destination node by the first node.
Second aspect, the embodiment of the present invention provide a kind of for facing the DTN distributed caching equipment of empty wagons earth mat, comprising:
Detection module, for detecting whether first node occurs congestion information；
Searching module is used for when congestion occurs for the first node, according to preset rules in the flat of the first node
In equal contact frequency table, current time is searched and second node that the first node is in contact；
Sending module, for forwarding intensity to select forwarding information according to the message of message each in the first node, and will
The forwarding information is sent to the second node, so that the forwarding message is sent to target section by the second node
Point.
The third aspect, the embodiment of the present invention provide a kind of for facing the DTN distributed caching equipment of empty wagons earth mat, comprising:
At least one processor and memory；
The memory stores computer executed instructions；
At least one described processor executes the computer executed instructions of memory storage so that it is described at least one
Processor executes method described in the various possible designs of first aspect and first aspect as above.
Fourth aspect, the embodiment of the present invention provide a kind of computer readable storage medium, the computer-readable storage medium
Computer executed instructions are stored in matter, when processor execute the computer executed instructions when, realize first aspect as above with
And method described in the various possible designs of first aspect.
It is provided in this embodiment for facing the DTN distributed caching method and equipment of empty wagons earth mat, this method passes through the
When congestion information occurs for one node, selected part information is sent to as forwarding information from each information cached in first node
From second node of the current time found in mean exposure frequency meter in first node communication coverage, so that this turn
Photos and sending messages are sent to destination node by second node.The DTN distributed caching provided in this embodiment for being used to face empty wagons earth mat
Method can alleviate network node congestion, realize the normal transmission of data；Neighbor node can be communicated by making full use of in network, dispersion
The pressure of congested node, increases network utilization；The transmission success rate that message can be improved, reduces the mean transit delay of message.
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 this hair
Bright some embodiments for those of ordinary skill in the art without any creative labor, can be with
It obtains other drawings based on these drawings.
Fig. 1 is the configuration diagram for facing abortive haul network that one embodiment of the invention provides；
Fig. 2 is that the process for the DTN distributed caching method for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to；
Fig. 3 is that the process for the DTN distributed caching method for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to；
Fig. 4 is that the structure for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to；
Fig. 5 is that the structure for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to；
Fig. 6 is the hardware knot for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides
Structure schematic diagram.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without creative efforts, shall fall within the protection scope of the present invention.
Fig. 1 be one embodiment of the invention provide face the configuration diagram of abortive haul network, as shown in Figure 1, facing abortive haul network and including
Dirigible node, unmanned plane node, ground tiny node and earth moving equipment node；The dirigible node can be aerostatics,
The earth moving equipment node can be the transit equipments such as automobile, train.During practical communication, above-mentioned each node is being sent out
It can communicate between two nodes of raw contact, wherein the position of dirigible node and ground tiny node is relatively fixed, they
Between the communication that can keep relative stability in most times, unmanned plane node and earth moving equipment node are high dynamic
Node, and the message of earth moving equipment node transmission is mostly voice, short-sighted frequency, information etc., so that business has largely
Property and it is sudden the features such as.For each node before encountering next-hop node, the message to be sent received can have been stored in this
In the caching of node, but the cache resources of node are limited, stored when node can not meet for a long time with next-hop node
Message can be more than nodal cache, generate congestion, influence the reception of subsequent message.Therefore, it is necessary to efficient buffer memory management methods to come
Alleviate congestion.
In the prior art, have for the research of cache management strategy and be much broadly divided into two classes: the plan based on Indigenous knowledge
Summary and the strategy based on network knowledge.When nodal cache is filled up by message, the former does not need the knowledge in network range, only according to
The Indigenous knowledge that message carries in caching, such as arrival time (arriving time), TTL (Time-To-Live), message
The decisions such as size (size) abandon which of caching message, and the message newly to arrive concedes space.Latter strategy is in determination
In caching when message loss priority, the included Indigenous knowledge of message is not only considered, it is also contemplated that network range is partly or completely
Whole knowledge, to make the message discard decision that can satisfy certain optimal performance index.
Specifically, the strategy based on Indigenous knowledge includes:
1. DL (Drop Last): when nodal cache is filled up by message, the message finally reached will be discarded,
When using FIFO (First In First Out) scheduling strategy, DL can guarantee that the data for being introduced into buffer queue have more
Repeater-transmitter meeting.
2. DF (Drop Front): when nodal cache overflows, the message for coming front end in buffer queue will be dropped,
When according to FIFO scheduling strategy, the message for reaching caching in queue at first will be dropped.In most cases, queue is come
The maximum probability that the message of front end has had copy to be transmitted to other nodes, therefore turn to improve the entirety of message in caching
Ratio is sent out, DF strategy abandons the message of queue front end.
3. DO (Drop Oldest): when nodal cache is filled up by message, abandon generation time in nodal cache is earliest
Oldest message, since oldest message has been survived the long period in a network, then producing a large amount of copy storage
Other nodes in a network, thus it is maximum a possibility that this kind of message has arrived at destination, it abandons it and causes this message not
It is minimum that destination node possibility can be successfully arrived at.
4. DY (Drop Youngest): corresponding with DO drop policy, DY strategy is when nodal cache is filled up by message
Abandon the i.e. minimus message of nearest time generation.
5. DR (Drop Random): the message when nodal cache overflows, in random drop buffer queue.
Specifically, the strategy based on network knowledge includes:
1. the cache management based on partial parameters priority: such as MOFO (evict Most Forwarded first), when
When cache congestion, strategy abandons the most message of hop count at first；According to the popularity (popularity) of message come really
Determine message drop policy, when caching is full, popularity is low to be first dropped.
2. optimizing cache management: according to a certain performance standard, such as time delay, delivery ratio, derive one about caching
In all message utility function, the corresponding effectiveness gain of each message, when two nodes meet, the message in caching is pressed
Message gain is maximum first to be sent, when nodal cache has been expired, by the smallest message of gain to abandoning, to make all disappear
The overall utility gain of breath is maximum.
3. adaptive cache management: being met information using nodes history, abandon the big message of collision probability.
4. cooperative caching management: regarding the caching of meet two nodes as an entirety, carried out according to certain rule
Distribution caching etc..
Time delay tolerant network (Delay Tolerant Networks, DTN) network is due to using " storage-carrying-forwarding "
Mode can solve the problems, such as the link down of high dynamic network, while (BP layers) of its unique beam layer designs very well, can shield
The otherness of lower-layer protocols, communication these cache management strategies between adapted to isomerous network can be alleviated to a certain extent
The congestion situation of DTN nodes has respective benefit and limitation, but the overwhelming majority has selected to lose in node congestion
A part of message is abandoned to alleviate congestion, there is lower message Successful transmissions rate.
In order to solve the above technical problems, the application provide it is a kind of for facing the DTN distributed caching method of empty wagons earth mat.This
Field technical staff is appreciated that distributed caching is used in computer system mostly, and client is asked to server-side transmission
When asking, if many time can be wasted by inquiring again from database every time, then some memories, there are multiple clients
In the memory of node, request is all first inquired in memory every time later, if not searching from database again, is substantially increased whole
The operational paradigm of body.In conjunction with above-mentioned technical problem, distributed caching management in this application specifically needs to consider following ask
Topic: 1. before distributed forwarding message temporarily stores, it is to be understood that the topology and caching situation of neighbor node；2. selection is suitable
Message carry out transfer storage, for message by certain rule settings forward intensity；3. according to the caching feelings of known neighbor node
The information such as condition and link and bandwidth select suitable node to carry out the forwarding of message；4. after the congestion relief of this node, such as
What fetches the message transferred from the neighbor node of temporary cache.
How to be solved with technical solution of the specifically embodiment to technical solution of the present invention and the application below above-mentioned
Technical problem is described in detail.These specific embodiments can be combined with each other below, for the same or similar concept
Or process may repeat no more in certain embodiments.Below in conjunction with attached drawing, the embodiment of the present invention is described.
Hereinafter, first in the application part term and symbol be explained, in order to those skilled in the art
Understand:
(1) it contacts (contact): in a network, when a node and another node meet and can communicate, claiming
It contacts.DTN nodes be it is dynamic, the contacts of two nodes will not last very long, and bandwidth in DTN network
It is limited, too many message can not be transmitted in the short time, so the contact frequency of two nodes determines the message transmitted each other
Amount, when contact frequency is higher, the transferable size of message of two nodes also can be more.When the history contact frequency of two nodes is very high
When, it can think that the two following nodes can meet again quickly with maximum probability, this is the forward node for selecting temporal cache message
Premise.
(2) symbol description:
A, b: any two node in network；
N: nodes total number；
t0: certain moment in network；
nt0(a, b): node a and node b are in t0The history frequency of exposure at moment；
T: time interval (T is sufficiently large, has statistical significance)；
nt0+T(a, b): node a and node b are in t0The history frequency of exposure at+T moment；
nΔT(a, b): in Δ T time section, node a and node b frequency of exposure (△ T=T)；
fT(k)(a, b): mean exposure frequency of the node a and node b within kth (k=1,2,3 ...) a period；
fMTI: message forwards intensity, and it is big to calculate a possibility that certain message is forwarded away in node congestion according to index
It is small.
(3) mean exposure frequency (ACF, Average Contact Frequency): setting and share N number of node in network,
Certain moment t0The history frequency of exposure that Shi Tongji obtains node a and node b is nt0(a, b), (T is sufficiently large, tool after T time
Have statistical significance), the history frequency of exposure of node a and node b are nt0+T(a, b), then in T time, the contact time of two nodes
Number is nΔt(a, b)=nt0+kT(a,b)-nt0+(k-1)T(a, b), Δ t=T, node are recalculating and other sections after T time
The frequency of exposure n of pointΔT(a, b), (a ≠ b, and 1≤b≤N-1), if contactless with some nodes, for initial value 0.Node a
With the calculation formula of mean exposure frequency of the node b within kth (k=1,2,3 ...) a period are as follows:
It further derives, by the e in contact matrixt(a, b) indicates contact situation of the node a with node b in t moment, et
(a, b)=1 indicates that two nodes have contact, e in t momentt(a, b)=0 item indicates that two nodes are contactless in t moment, wherein t0+(k-
1)T<t<t0+ kT, (k=1,2,3 ...).Then in a period interior nodes a of kth (k=1,2,3 ...) and the contact of node b time
The sum of number can indicate are as follows:
It can be derived by above two formula:
(4) message forwarding intensity (MTI, Message Transmit Intensity): if the maximum value of all message
For msg_size_max, the life cycle of message is msg_live, and the size of current message is msg_size, and remaining life cycle is
It is as follows to can define forwarding strength formula by msg_live_remain:
Message forwards intensity bigger, then it is assumed that in node congestion, the message is transmitted to other nodes as forwarding message
Possibility is bigger.fMTIIt can be used as and be attached to message header with the attribute that message carries.
Fig. 2 is that the process for the DTN distributed caching method for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to.As shown in Fig. 2, this method comprises:
201, whether detection first node occurs congestion information.
In practical application, the executing subject of the present embodiment is first node or the control equipment that first node is arranged in.
The first node can be DTN network node, for example, the first node can be to face dirigible (floating in space in abortive haul network
Device), unmanned plane etc..
Specifically, each node in DTN network is before encountering next-hop node, from other nodes it is received to be transmitted to
The message of destination node can have been stored in the caching of this node, but the cache resources of node are limited, when node long-time nothing
When method and next-hop node meet, stored message can be more than nodal cache, generate congestion, influence the reception of subsequent message.
It is alternatively possible to detect first segment by the way that whether the information content that judges first node storage is more than the buffer memory capacity of the node
Whether point occurs congestion information, determines first node if the information content of node storage is more than the buffer memory capacity of the node
Congestion information determines that information does not occur and gathers around for first node if the information content that the node stores is without departing from the buffer memory capacity of the node
Plug.
Optionally, facing abortive haul network and can use delay/interruption tolerable network where first node in the present embodiment
(Delay/Disruption-Tolerant Network, DTN), DTN network use " storage-carrying-forwarding " mode, can be with
The link down of high dynamic network, while (BP layers) of its unique beam layer designs are solved the problems, such as very well, can shield lower-layer protocols
Otherness, the communication between adapted to isomerous network.
If 202, occurring, according to preset rules in the mean exposure frequency meter of the first node, when searching current
Carve the second node being in contact with the first node.
It can be to face each node (unmanned plane, aerostatics, earth moving equipment) in abortive haul network to establish averagely in practical application
Contact frequency table, with count and record each node being in contact with first node respectively with the mean exposure of the first node frequency
Rate.By the foundation and maintenance of the mean exposure frequency meter, it will appreciate that interaction is frequent in each node contacted with first node
Degree interacts frequent good cache node with first node as second node consequently facilitating selecting, is conducive to subsequent incite somebody to action
The information retrieval of unloading or the information for directly sending unloading to destination node by the second node.
Optionally, from the mean exposure frequency meter of the first node search second node institute according to preset rules can
To be to look for the maximum node of mean exposure frequency in table, the specific steps of lookup may include: by the first node
Each mean exposure frequency descending arrangement in mean exposure frequency meter obtains first list；According to the sequence of the first list,
It successively detects whether each node is in contact at current time and the first node, is sent out until getting with the first node
The node of the preset quantity of raw contact；Using the node of the preset quantity as the second node.
Specifically, traversing the ACF table of this node (first node) maintenance, arranged according to ACF value descending in table.Search ranking
Whether first node contacts with this node at current time, and cache node is used as if having, if it is contactless search it is next
It is a.Settable most cache node numbers are L.Cache node number is fewer, and when subsequent retrieval message is more convenient.
203, it forwards intensity to select forwarding information according to the message of message each in the first node, and the forwarding is believed
Breath is sent to the second node, so that the forwarding message is sent to destination node by the second node.
In practical application, when message congestion occurs for first node, need to remove the information of part from caching, ability
Reserve the message that enough spaces receive the subsequent transmission of other nodes.Which message is specifically selected as forwarding information, Ke Yiyou
Various ways, such as can be according to the successive of information deposit, it can also be according to the storage location of information, it can also be according to information
Popularity.It is not limited this in the present embodiment.
Optionally, intensity is forwarded by message to have in much in the way of select forwarding message, such as can choose message
Forward the message of maximum intensity as forwarding message.The specific implementation step of which may include:
2031, the message for obtaining each message of first node described in current time forwards intensity；
2032, the message forwarding intensity of each message is arranged according to descending；
2033, the capacity for occupying each message in the first ranking to N ranking is summed, and obtains total capacity；
2034, judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released；
2035, if it is not, the capacity for then occupying each message in the first ranking to N+1 ranking is summed, total capacity is obtained；
2036, step 2034 and step 2035 are repeated, until the total capacity is more than or equal to the first node
Preset amount of ram to be released；
2037, if so, using each message in the first current ranking to N+1 ranking as forwarding message.
Specifically, being arranged according to the MTI value descending of message, successively conduct when congestion occurs for this node (first node)
Forward message.Forwarding message institute releasing memory size may be configured as the x% (x is less than 50) of this nodal cache.If coming first
Institute's releasing memory then continues to forward second message, until meeting x% less than x% after message forwarding.
Optionally, in such a way that the forwarding information is sent to destination node by second node can there are many, for example,
The forwarding information directly can be sent to by target section by second node when second node and destination node are in contact
Forwarding information can also be returned to first node by second node by point, when being destination node contact by first node, hair
Give destination node.The present embodiment does not limit this.
The DTN distributed caching method provided in this embodiment for being used to face empty wagons earth mat, by believing in first node
When ceasing congestion, selected part information is sent to as forwarding information from mean exposure frequency from each information cached in first node
Second node of the current time found in rate table in first node communication coverage, so that the forwarding information passes through the
Two nodes are sent to destination node.DTN distributed caching method provided in this embodiment for facing empty wagons earth mat can protected
Congestion information is released under the premise of full information integrality, improves message transmission success rate, to improve communication quality, is promoted and is used
Family experience.Specifically, according to the thought of distributed caching and the network characteristics for facing empty wagons earth mat, it is provided in this embodiment for facing
The DTN distributed caching method of empty wagons earth mat has the advantage that 1) alleviation network node congestion, realizes the normal biography of data
It is defeated；2) neighbor node can be communicated by making full use of in network, dispersed the pressure of congested node, increased network utilization；3) it can be improved
The transmission success rate of message, reduces the mean transit delay of message.
Fig. 3 is that the process for the DTN distributed caching method for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to.As shown in figure 3, on the basis of the above embodiments, the present embodiment has carried out more complete description, the party to whole flow process
Method includes:
301, the mean exposure frequency meter of first node is created, and the mean exposure frequency meter is updated.
Optionally, step 301 can specifically include:
3011, the mean exposure frequency meter of the first node is created；The contact frequency table includes the first node
Buffer memory capacity information.
Specifically, one ACF table of each node maintenance at the beginning of network is established, the original state of the table only have FB (free
Buffer) information.It is as follows:
ACF information comprising all nodes crossed with the node contact, format are as follows:
3012, detect whether that there are third nodes and the first node to be in contact.
3013, the history frequency of exposure of first node described in current time Yu third node if it exists, is then obtained.
3014, the mean exposure between the first node and the third node is calculated according to the history frequency of exposure
Frequency；And the contact frequency table is updated with the mean exposure frequency.
Specifically, in the maintenance and renewal process of ACF table,
For the update of FB information: when this node and other nodes contact, no matter whether other nodes had before
Contact, all update FB information.
For F (a, x) information: one new node of every contact increases a line ACF information (F (a, x)), and calculation formula is public
Formula (3) is described；If the node of contact once contacted, does not increase new ACF information, in having that corresponding ACF information, press
The statistics frequency of exposure.Finally formed ACF sheet format is as follows:
It is alternatively possible to refresh F (a, x) information in ACF table according to the frequency of exposure counted every T time.
302, whether detection first node occurs congestion information.
If 303, occurring, according to preset rules in the mean exposure frequency meter of the first node, when searching current
Carve the second node being in contact with the first node.
In the present embodiment, step 302 and step 303 are similar with step 201 in above-described embodiment and step 202, herein
It repeats no more.
304, judge whether the buffer memory capacity information of the second node meets preset condition.
Optionally, judgment method can there are many kinds of, for example, the buffer memory capacity information includes the surplus of the second node
Ratio between remaining buffer memory capacity and total buffer memory capacity, judgment method can specifically include:
Judge whether the ratio is greater than preset threshold.
If more than then the buffer memory capacity information of the second node meets preset condition.
Specifically, being communicated with cache node (second node), the remaining cache (FB) in query caching node ACF table
Situation.If FB is more than or equal to the p% (p is the minimum value that the step can be performed) that the cache node always caches, send messages to
The node, and the node number of the node is recorded, so as to subsequent retrieval message；If FB is less than the p% that the node always caches, this is abandoned
Node can select next cache node in the way of described in step 102.If the message forwarded in this step is less than first segment
Point releasing memory size, then can increase a cache node in the way of step 102, continue to forward message.Until all slow
The capacity for depositing node can reach the memory size of first node release.
305, if satisfied, forwarding intensity to select forwarding information according to the message of message each in the first node, and by institute
It states forwarding information and is sent to the second node, so that the forwarding message is sent to destination node by the second node.
Step 305 is similar with step 203 in above-described embodiment in the present embodiment, and details are not described herein again.
306, the forwarding information is sent to by destination node by second node.
Optionally, in such a way that the forwarding information is sent to destination node by second node can there are many, for example,
The forwarding information directly can be sent to by target section by second node when second node and destination node are in contact
Forwarding information can also be returned to first node by second node by point, when being destination node contact by first node, hair
Give destination node.The present embodiment does not limit this.
Specifically, forwarding information is returned to first node so that forwarding information is sent to destination node by second node
Method, can specifically include following steps:
Judge whether the first node is in contact with the second node；
If so, fetching control signal so that the second node returns the forwarding information to second node transmission
It is back to the first node；
The forwarding information is sent to destination node by the first node.
The DTN distributed caching method provided in this embodiment for being used to face empty wagons earth mat, by believing in first node
When ceasing congestion, selected part information is sent to as forwarding information from mean exposure frequency from each information cached in first node
Second node of the current time found in rate table in first node communication coverage, so that the forwarding information passes through the
Two nodes are sent to destination node.DTN distributed caching method provided in this embodiment for facing empty wagons earth mat can protected
Congestion information is released under the premise of full information integrality, improves message transmission success rate, to improve communication quality, is promoted and is used
Family experience.
Fig. 4 is that the structure for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to.As shown in figure 4, the DTN distributed caching equipment 40 for being used to face empty wagons earth mat includes: detection module 401, searching module
402 and sending module 403.
Detection module 401, for detecting whether first node occurs congestion information.
Searching module 402 is used for when congestion occurs for the first node, according to preset rules in the first node
In mean exposure frequency meter, the second node that current time and the first node are in contact is searched.
Sending module 403, for forwarding intensity to select forwarding information according to the message of message each in the first node, and
The forwarding information is sent to the second node, so that the forwarding message is sent to target section by the second node
Point.
The DTN distributed caching equipment provided in this embodiment for being used to face empty wagons earth mat, by detection module in first segment
Point occur congestion information when, sending module from each information cached in first node selected part information as forwarding information simultaneously
Searching module is sent to from being found in mean exposure frequency meter at current time in first node communication coverage
Second node, so that the forwarding information is sent to destination node by second node.It is provided in this embodiment to be used for facing empty wagons
The DTN distributed caching method of net can release congestion information under the premise of saving information integrity from damage, improve message transmission
Success rate promotes user experience to improve communication quality.
Fig. 5 is that the structure for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides is shown
It is intended to.As shown in figure 5, this is used to face the DTN distributed caching equipment 40 of empty wagons earth mat further include: creation module 404, first are sentenced
Disconnected module 405 obtains module 406, processing module 407.
Optionally, the equipment further include:
Creation module 404, for creating the mean exposure frequency meter of the first node；The contact frequency table includes institute
State the buffer memory capacity information of first node.
First judgment module 405, for detecting whether there are third nodes and the first node to be in contact；
Module 406 is obtained, for obtaining current time institute when being in contact there are third node and the first node
State the history frequency of exposure of first node Yu third node.
Processing module 407, for according to the history frequency of exposure calculate the first node and the third node it
Between mean exposure frequency；And the contact frequency table is updated with the mean exposure frequency.
Optionally, the searching module is specifically used for: will be each average in the mean exposure frequency meter of the first node
The arrangement of contact frequency descending obtains first list；According to the sequence of the first list, whether each node is successively detected current
Moment is in contact with the first node, until getting the node for the preset quantity being in contact with the first node；
Using the node of the preset quantity as the second node.
Optionally, the sending module is specifically used for:
The message for obtaining each message of first node described in current time forwards intensity.
The message forwarding intensity of each message is arranged according to descending.
The capacity summation that each message in first ranking to N ranking is occupied, obtains total capacity.
Judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released.
If it is not, the capacity for then occupying each message in the first ranking to N+1 ranking is summed, total capacity is obtained.
Repeat it is described judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released,
If it is not, the step of then capacity of each message occupancy in the first ranking to N+1 ranking is summed, obtains total capacity, until institute
It states total capacity and presets amount of ram to be released more than or equal to the first node.
If so, using each message in the first current ranking to N+1 ranking as forwarding message.
Optionally, the equipment further include:
Second judgment module, for judging whether the buffer memory capacity information of the second node meets preset condition.
The sending module, specifically for when the buffer memory capacity of the second node meets preset condition, according to second
Preset rules select forwarding information, and the forwarding information is sent to the second node.
Optionally, the buffer memory capacity information includes between the residual caching capacity of the second node and total buffer memory capacity
Ratio；Second judgment module is specifically used for:
Judge whether the ratio is greater than preset threshold.
If more than then the buffer memory capacity information of the second node meets preset condition.
Optionally, the equipment further include:
Third judgment module, for whether judging the first node after the alleviation of the congestion information of the first node
It is in contact with the second node.
Module is fetched, for when the first node and the second node are in contact, Xiang Suoshu second node to be sent out
It send and fetches control signal so that the forwarding information is back to the first node by the second node, to pass through described first
The forwarding information is sent to destination node by node.
The DTN distributed caching equipment provided in an embodiment of the present invention for being used to face empty wagons earth mat, can be used for executing above-mentioned
Embodiment of the method, it is similar that the realization principle and technical effect are similar, and details are not described herein again for the present embodiment.
Fig. 6 is the hardware knot for the DTN distributed caching equipment for facing empty wagons earth mat that further embodiment of this invention provides
Structure schematic diagram.As shown in fig. 6, provided in this embodiment for face the DTN distributed caching equipment 60 of empty wagons earth mat to include: at least
One processor 601 and memory 602.This further includes communication component for facing the DTN distributed caching equipment 60 of empty wagons earth mat
603.Wherein, processor 601, memory 602 and communication component 603 are connected by bus 604.
During specific implementation, at least one processor 601 executes the computer execution that the memory 602 stores and refers to
It enables, so that at least one processor 601 executes as above for facing use performed by the DTN distributed caching equipment 60 of empty wagons earth mat
In the DTN distributed caching method for facing empty wagons earth mat.
When the first node of the present embodiment sends forwarding information to other nodes, which can will be forwarded
Information is sent to the nodes such as second node or destination node.
The specific implementation process of processor 601 can be found in above method embodiment, and it is similar that the realization principle and technical effect are similar,
Details are not described herein again for the present embodiment.
In above-mentioned embodiment shown in fig. 6, it should be appreciated that processor can be central processing unit (English:
Central Processing Unit, referred to as: CPU), can also be other general processors, digital signal processor (English:
Digital Signal Processor, referred to as: DSP), specific integrated circuit (English: Application Specific
Integrated Circuit, referred to as: ASIC) etc..General processor can be microprocessor or the processor is also possible to
Any conventional processor etc..Hardware processor can be embodied directly in conjunction with the step of invention disclosed method to have executed
At, or in processor hardware and software module combination execute completion.
Memory may include high speed RAM memory, it is also possible to and it further include non-volatile memories NVM, for example, at least one
Magnetic disk storage.
Bus can be industry standard architecture (Industry Standard Architecture, ISA) bus, outer
Portion's apparatus interconnection (Peripheral Component, PCI) bus or extended industry-standard architecture (Extended
Industry Standard Architecture, EISA) bus etc..Bus can be divided into address bus, data/address bus, control
Bus etc..For convenient for indicating, the bus in illustrations does not limit only a bus or a type of bus.
The application also provides a kind of computer readable storage medium, and calculating is stored in the computer readable storage medium
Machine executes instruction, and when processor executes the computer executed instructions, realizes as above distributed for facing the DTN of empty wagons earth mat
The DTN distributed caching method for being used to face empty wagons earth mat that buffer memory device executes.
The application also provides a kind of computer readable storage medium, and calculating is stored in the computer readable storage medium
Machine executes instruction, and when processor executes the computer executed instructions, realizes as above distributed for facing the DTN of empty wagons earth mat
The DTN distributed caching method for being used to face empty wagons earth mat that buffer memory device executes.
Above-mentioned computer readable storage medium, above-mentioned readable storage medium storing program for executing can be by any kind of volatibility or non-
Volatile storage devices or their combination realize that, such as static random access memory (SRAM), electrically erasable is only
It reads memory (EEPROM), Erasable Programmable Read Only Memory EPROM (EPROM), programmable read only memory (PROM) is read-only to deposit
Reservoir (ROM), magnetic memory, flash memory, disk or CD.Readable storage medium storing program for executing can be general or specialized computer capacity
Any usable medium enough accessed.
A kind of illustrative readable storage medium storing program for executing is coupled to processor, to enable a processor to from the readable storage medium storing program for executing
Information is read, and information can be written to the readable storage medium storing program for executing.Certainly, readable storage medium storing program for executing is also possible to the composition portion of processor
Point.Processor and readable storage medium storing program for executing can be located at specific integrated circuit (Application Specific Integrated
Circuits, referred to as: ASIC) in.Certainly, processor and readable storage medium storing program for executing can also be used as discrete assembly and be present in equipment
In.
Those of ordinary skill in the art will appreciate that: realize that all or part of the steps of above-mentioned each method embodiment can lead to
The relevant hardware of program instruction is crossed to complete.Program above-mentioned can be stored in a computer readable storage medium.The journey
When being executed, execution includes the steps that above-mentioned each method embodiment to sequence；And storage medium above-mentioned include: ROM, RAM, magnetic disk or
The various media that can store program code such as person's CD.
Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Pipe present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that: its according to
So be possible to modify the technical solutions described in the foregoing embodiments, or to some or all of the technical features into
Row equivalent replacement；And these are modified or replaceed, various embodiments of the present invention technology that it does not separate the essence of the corresponding technical solution
The range of scheme.
Claims (10)
1. a kind of for facing the DTN distributed caching method of empty wagons earth mat characterized by comprising
Whether detection first node occurs congestion information；
If occur, according to preset rules in the mean exposure frequency meter of the first node, search current time with it is described
The second node that first node is in contact；
It forwards intensity to select forwarding information according to the message of message each in the first node, and the forwarding information is sent to
The second node, so that the forwarding message is sent to destination node by the second node.
2. the method according to claim 1, wherein being averaged in the first node according to preset rules
In contact frequency table, before the second node that lookup current time is communicated with the first node, further includes:
Create the mean exposure frequency meter of the first node；The contact frequency table includes the buffer memory capacity of the first node
Information；
Detect whether that there are third nodes and the first node to be in contact；
If it exists, then the history frequency of exposure of first node described in current time Yu third node is obtained；
The mean exposure frequency between the first node and the third node is calculated according to the history frequency of exposure；And with
The mean exposure frequency is updated the contact frequency table.
3. the method according to claim 1, wherein including and the first segment in the mean exposure frequency meter
Mean exposure frequency between the point each node and the first node that are in contact, it is described according to preset rules described first
In the mean exposure frequency meter of node, the second node that current time and the first node are in contact is searched, comprising:
Each mean exposure frequency descending arrangement in the mean exposure frequency meter of the first node is obtained into first list；
According to the sequence of the first list, successively detect whether each node connects at current time and the first node
Touching, until getting the node for the preset quantity being in contact with the first node；
Using the node of the preset quantity as the second node.
4. the method according to claim 1, wherein the message according to message each in the first node turns
It sends out intensity and selectes forwarding information, comprising:
The message for obtaining each message of first node described in current time forwards intensity；
The message forwarding intensity of each message is arranged according to descending；
The capacity summation that each message in first ranking to N ranking is occupied, obtains total capacity；
Judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released；
If it is not, the capacity for then occupying each message in the first ranking to N+1 ranking is summed, total capacity is obtained；
Repeat it is described judge that whether the total capacity be more than or equal to the first node presets amount of ram to be released, if
The step of no, then the capacity occupied each message in the first ranking to N+1 ranking is summed, and obtains total capacity, until described
Total capacity presets amount of ram to be released more than or equal to the first node；
If so, using each message in the first current ranking to N+1 ranking as forwarding message.
5. the method according to claim 1, wherein the message according to message each in the first node turns
It sends out intensity and selectes forwarding information, and the forwarding information is sent to before the second node, further includes:
Judge whether the buffer memory capacity information of the second node meets preset condition；
It is described to forward intensity to select forwarding information according to the message of message each in the first node, and the forwarding information is sent out
It send to the second node, comprising:
If satisfied, then selecting forwarding information according to the second preset rules, and the forwarding information is sent to the second node.
6. according to the method described in claim 5, it is characterized in that, the buffer memory capacity information includes the surplus of the second node
Ratio between remaining buffer memory capacity and total buffer memory capacity, it is pre- whether the buffer memory capacity information for judging the second node meets
If condition, comprising:
Judge whether the ratio is greater than preset threshold；
If more than then the buffer memory capacity information of the second node meets preset condition.
7. method according to claim 1-6, which is characterized in that described according to message each in the first node
Message forwarding intensity select forwarding information, and the forwarding information is sent to after the second node, further includes:
After the congestion information of the first node is alleviated, judge whether the first node connects with the second node
Touching；
If so, fetching control signal so that the forwarding information is back to by the second node to second node transmission
The first node, the forwarding information is sent to destination node by the first node.
8. a kind of for facing the DTN distributed caching equipment of empty wagons earth mat characterized by comprising
Detection module, for detecting whether first node occurs congestion information；
Searching module, for being connect in being averaged for the first node according to preset rules when congestion occurs for the first node
It touches in frequency meter, the second node that lookup current time is in contact with the first node；
Sending module, for forwarding intensity to select forwarding information according to the message of message each in the first node, and will be described
Forwarding information is sent to the second node, so that the forwarding message is sent to destination node by the second node.
9. a kind of for facing the DTN distributed caching equipment of empty wagons earth mat characterized by comprising at least one processor and
Memory；
The memory stores computer executed instructions；
At least one described processor executes the computer executed instructions of the memory storage, so that at least one described processing
Device executes as described in any one of claim 1 to 7 for facing the DTN distributed caching method of empty wagons earth mat.
10. a kind of computer readable storage medium, which is characterized in that be stored with computer in the computer readable storage medium
It executes instruction, when processor executes the computer executed instructions, realizes as described in any one of claim 1 to 7 be used for
Face the DTN distributed caching method of empty wagons earth mat.
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