CN107786941B - File cooperation downloading method based on prefetching - Google Patents
File cooperation downloading method based on prefetching Download PDFInfo
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- CN107786941B CN107786941B CN201710910561.9A CN201710910561A CN107786941B CN 107786941 B CN107786941 B CN 107786941B CN 201710910561 A CN201710910561 A CN 201710910561A CN 107786941 B CN107786941 B CN 107786941B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/02—Services making use of location information
- H04W4/023—Services making use of location information using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
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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
- H04L67/01—Protocols
- H04L67/06—Protocols specially adapted for file transfer, e.g. file transfer protocol [FTP]
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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
- H04L67/5681—Pre-fetching or pre-delivering data based on network characteristics
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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
- H04L67/60—Scheduling or organising the servicing of application requests, e.g. requests for application data transmissions using the analysis and optimisation of the required network resources
- H04L67/63—Routing a service request depending on the request content or context
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Abstract
The invention discloses a file cooperation downloading method based on prefetching, which comprises the following steps of 1: data prefetching, which occurs when a target vehicle just enters a communication range set by a road; step 2: downloading data, which occurs when the target vehicle and the reverse cooperative vehicle are within the coverage of the road arrangement; and step 3: data forwarding occurs when a target vehicle and cluster members meet in a blind area; the invention combines the data pre-fetching and carrying-forwarding mechanism, can further reduce the blind area, indirectly expand the coverage area of the RSU, meet the requirement of large-scale content downloading, improve the file downloading quality, meet the user requirement, can be used for the communication between vehicles and road facilities and between vehicles, and solves the problems of small communication coverage area and large communication blind area caused by the sparse distribution of the RSU and the rapid movement of the vehicles on the expressway.
Description
Technical Field
The invention belongs to the technical field of communication, and mainly relates to a file downloading method in a vehicle self-organizing network, which can be used for communication between vehicles and road facilities and between vehicles.
Background
Vehicle ad hoc networks are the basis for the development of intelligent transportation systems, aiming to provide drivers and passengers with a large number of safety and entertainment applications. For any type of application, efficient data transfer is the basis. In particular, many applications include multimedia content of the type of pictures, music, and video. These contents can provide data visualization, further enhancing the driving experience of the user. Thus, its downloading and distribution is becoming increasingly important and worthy of study. Multimedia files are typically large and the download of the file can be achieved from vehicle to vehicle and from communication between the vehicle (V2V) and the infrastructure (V2I). For V2V, the high speed mobility of the vehicle, severe channel fading and strong mutual interference cause communication instability, so that it can only provide a small file download capacity. The V2I communication also cannot satisfy the downloading requirement of large files, mainly because of the following two aspects: on the one hand, the high maintenance cost of the road layout makes its distribution sparse, and therefore, there are many areas on the road without signals. On the other hand, the high speed mobility of the vehicle makes the time during which it can stay within the coverage of the road infrastructure very short. Therefore, a reasonable vehicle-to-road setup, large file download mechanism in vehicle-to-vehicle communication is very important to improve the user experience.
In the existing file downloading mechanisms, most of the files are downloaded cooperatively only by considering cooperation between vehicles. Typical mechanisms are an assisted data distribution mechanism CCDSV and a content cooperative distribution strategy among a plurality of road facilities based on cooperative game theory. The CCDSV mechanism increases the diversity of content flow patterns in the vehicle ad hoc network by distributing data to the moving target vehicles with higher efficiency by considering mobility prediction of the vehicles, resource storage of the AP sites, and content sharing distribution. The cooperative game theory-based content cooperative distribution strategy among the multiple road facilities firstly considers the difference of data circulation sharing rates caused by the difference of factors such as density and speed of vehicle nodes in different areas of a bottom layer V2V network, and carries out level division on a large amount of data in the network based on the difference. On the basis, the problem of cooperatively distributing data by a plurality of routers is regarded as a cooperative game problem, and a distributed algorithm is proposed for realizing. However, none of the content distribution mechanisms based on the V2V communication technology can cope with the problems of intermittent and frequent network accesses to the road equipment by vehicles in a Drive-thru network, so recent research focuses mainly on joint communication between vehicles and road equipment.
Disclosure of Invention
The invention aims to provide a large file downloading method in vehicle-to-road installation and vehicle-to-vehicle communication aiming at the defects of the prior art so as to improve the file downloading quality and meet the user requirements.
In order to achieve the purpose, the invention adopts the following technical scheme:
a file collaboration downloading method based on prefetching comprises the following steps:
1a) registering the characteristic information of the vehicle, and randomly selecting a communication range of a road device with the nearest distance for the target vehicle to enter;
1b) the target vehicle sends a downloading request to a remote data server;
1c) the target vehicle sends a request for appropriately prefetching the residual part of the file to the next two adjacent road devices;
step 2, data downloading stage: when the target vehicle and the reverse cooperative vehicle are within the coverage of the road arrangement;
2a) by adopting a priority mechanism, the target vehicle directly downloads data from the nearest road arrangement through V2I communication;
2b) the next two adjacent road arrangements respectively select a plurality of vehicles to form a cluster, and the cluster members also adopt the mode in 2a) to download part of files for the target vehicles from the adjacent road arrangements in a cooperation manner;
step 3, data forwarding stage: when the target vehicle and the cluster member meet in the blind area;
3a) the target vehicle receives data from multiple clusters via V2V communication.
As a further aspect of the invention, wherein in step 2a) the amount of data E [ D ] that the target vehicle can receive from the road infrastructure in one cycle is calculatedI]The calculation formula is as follows:
wherein: m is the number of intervals divided according to the communication rate, and the communication rate of the M intervals can be expressed as: w ═ W1,W2,...,WM}，τiIndicating the time the target vehicle lingers in the ith zone.
As a further aspect of the present invention, wherein the target vehicle is calculated to be [0, t ] in the step 2b)]Average amount of data D that can be downloadedaveThe calculation formula is as follows:
wherein: p is a radical of0Indicating a probability of at least one cooperating vehicle being present in a coverage area of the roadway; p is a radical ofcRepresenting the probability that c cooperative vehicles exist in the coverage area of the road arrangement at the same time; m represents that the road arrangement coverage area is divided into M areas; wiThe transmission rate of the ith area in the routing coverage range is represented; lambda [ alpha ]wIs a parameter when an inverted vehicle arrives in poisson; t isiIs the target vehicle's sojourn time in the ith zone; t is the time required by the target vehicle to drive through two adjacent roads at a constant speed, and is also the cycle time.
As a further aspect of the present invention, wherein the data amount E [ D ] that can be obtained when the target vehicle passes through the blind area is calculated in said step 3a)V]The calculation formula is as follows:
wherein: e [ L ]c]Is the length of the ideal cluster, E [ L ]inter]Is the ideal spacing between two clusters, r is the communication distance between vehicles, ve,vwThe traveling speeds of the forward vehicle and the reverse vehicle, respectively, and w is the vehicle-to-vehicle communication rate.
The invention has the beneficial effects that: the invention designs a simple analysis framework for the throughput of downloaded files, combines a data prefetching mechanism and a carrying-forwarding mechanism, can further reduce blind areas, indirectly expand the coverage area of RSUs to meet the requirement of large-scale content downloading, improve the file downloading quality, meet the requirement of users, can be used for communication between vehicles and road facilities and between vehicles, and solve the problems of small communication coverage area and large communication blind area caused by the sparse distribution of the RSUs and the rapid movement of the vehicles on a highway.
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FIG. 1 is a diagram of a scenario in which the present invention is used;
fig. 2 is a flow chart of an implementation of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
The overall design of the invention is as follows: randomly selecting a target vehicle to enter a road set RSU closest to the vehicleiThe communication range of (1) sending a request for downloading data to a remote data server, sending a request for prefetching data to a plurality of selected RSUs, then selecting reverse vehicles to form linear clusters, and downloading partial file contents respectively when cluster members drive through the selected RSUs in sequence. And finally, when the target vehicle and the cluster member meet in the blind area, the cluster member forwards the downloaded data to the target vehicle, so that the blind area is reduced, and the data downloading amount is increased.
Referring to fig. 1, the present invention uses a scenario in which two vehicles running in opposite directions are distributed on a section of a road, and the road is regularly distributed on a road on one side of the two lanes by a distance d. Wherein R is the wireless communication range of a certain road device, 2R is the road length that the vehicle can directly communicate with the certain road device,
are all areas uncovered by road installations (blind areas), in which
Is the front half of the blind area,
is the rear half part of the blind area,
length of (1) and
are equal.
Referring to fig. 2, the detailed implementation steps of the present invention are as follows:
step 1: and (6) data prefetching.
1a) Registering feature information of a vehicle
The characteristic information can be represented by a three-dimensional array < idi,vi,tiIs represented by, wherein idiIs an identifier of the vehicle, viIs the speed of the vehicle, tiIs the current time;
1a) randomly selecting a target vehicle to enter the RSUiCommunication range of
Assuming that vehicles arrive in an approximate poisson process and the traffic flow densities in one direction are all constant rho, the arrival rate lambda of the vehicles is:
wherein: v. offIs the maximum speed, p, allowed for the vehiclejamIs the traffic jam density at which the traffic flow tends to stop;
1b) target vehicle sends download request to remote data server
Broadcasting own idle state information when the router service finishes one request; when a node with a downloading requirement listens the idle state information, sending request information to the router;
1c) the target vehicle gives two adjacent Road Sets (RSU)i+1,RSUi+2) A request is issued to appropriately prefetch the remaining portion of the file, respectively.
Step 2: and (6) downloading data.
2a) With the prioritization mechanism, the target vehicle communicates directly from the RSU via V2IiTo download data
It is assumed that the priority of communication between the vehicle and the road device is higher than the priority of communication between the vehicle and the vehicle, i.e., the target vehicle cannot communicate with other vehicles when downloading data from the road device. And assuming that the communication speed between the vehicle and the road arrangement is only dependent on the distance between the target vehicle and the corresponding road arrangement, the data quantity E [ D ] that the target vehicle can receive from the road arrangement in one periodI]Comprises the following steps:
wherein: m is the number of intervals divided according to the communication rate, and the communication rate of the M intervals can be expressed as: w ═ W1,W2,...,WM}，τiTo representThe time that the target vehicle lingers in the ith zone;
2b)RSUi+1and RSUi+2Selecting a number of vehicles to form a cluster, respectively, the cluster members likewise taking the form of 2a) for the target vehicle from the RSUi+1Or RSUi+2Process collaborative download of partial files
On-highway VANET networks are prone to intermittent connectivity, so it is necessary to assemble cooperating vehicles into a linear cluster. Target vehicle is at [0, t]Average amount of data D that can be downloadedaveComprises the following steps:
wherein: p is a radical of0Indicating a probability of at least one cooperating vehicle being present in a coverage area of the roadway; p is a radical ofcRepresenting the probability that c cooperative vehicles exist in the coverage area of the road arrangement at the same time; m represents that the road arrangement coverage area is divided into M areas; wiThe transmission rate of the ith area in the routing coverage range is represented; lambda [ alpha ]wIs a parameter when an inverted vehicle arrives in poisson; t isiIs the target vehicle's sojourn time in the ith zone; t is the time required by the target vehicle to drive through two adjacent roads at a constant speed, and is also the cycle time.
And step 3: and (6) forwarding the data.
3a) Target vehicles receive data from multiple clusters via V2V communication
Cooperating vehicles tend to be clustered, with vehicles in successive clusters typically moving a relatively large distance apart. The amount of data that the target vehicle can obtain via V2V communication depends on the one hand on the number of clusters that the target vehicle can encounter; on the other hand, it is also limited by the amount of data that the cluster can transmit to the target vehicle. The amount of data E D that can be obtained when the target vehicle passes through the blind zone, assuming that sufficient data is available for each cluster to transmit to the target vehicleV]Comprises the following steps:
wherein: e [ L ]c]Is the length of the ideal cluster, E [ L ]inter]Is the ideal spacing between two clusters, r is the communication distance between vehicles, ve,vwThe traveling speeds of the forward vehicle and the reverse vehicle, respectively, and w is the vehicle-to-vehicle communication rate.
The invention combines the data pre-fetching and carrying-forwarding mechanism, can further reduce the blind area, indirectly expand the coverage area of the RSU, meet the requirement of large-scale content downloading, improve the file downloading quality, meet the user requirement, can be used for the communication between vehicles and road facilities and between vehicles, and solves the problems of small communication coverage area and large communication blind area caused by the sparse distribution of the RSU and the rapid movement of the vehicles on the expressway.
The foregoing is a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that variations, modifications, substitutions and alterations can be made in the embodiment without departing from the principles and spirit of the invention.
Claims (6)
1. A file collaboration downloading method based on prefetching is characterized by comprising the following steps:
step 1: data prefetching, which occurs when a target vehicle just enters a communication range set by a road;
1a) registering the characteristic information of the vehicle, and randomly selecting a communication range of a road device with the nearest distance for the target vehicle to enter;
1b) the target vehicle sends a downloading request to a remote data server;
1c) the target vehicle sends a request for appropriately prefetching the residual part of the file to the next two adjacent road devices;
step 2: downloading data, which occurs when the target vehicle and the reverse cooperative vehicle are within the coverage of the road arrangement;
2a) by adopting a priority mechanism, the target vehicle directly downloads data from the nearest road arrangement through V2I communication;
2b) the next two adjacent road arrangements respectively select a plurality of vehicles to form a cluster, and the cluster members also adopt the mode in 2a) to download part of files for the target vehicles from the adjacent road arrangements in a cooperation manner;
and step 3: data forwarding occurs when a target vehicle and cluster members meet in a blind area;
3a) the target vehicle receives data from a plurality of clusters via V2V communication, wherein an amount of data E D available when the target vehicle passes through the blind zone is calculatedV]The calculation formula is as follows:
wherein: e [ L ]c]Is the length of the ideal cluster, E [ L ]inter]Is the ideal spacing between two clusters, r is the communication distance between vehicles, ve,vwThe driving speeds of a forward vehicle and a reverse vehicle are respectively, w is the communication speed between the vehicles, d is the distance of a road arrangement regularly distributed on a road on one side of two lanes, and R is the wireless communication range of a certain road arrangement.
2. The prefetch-based file cooperative downloading method according to claim 1, wherein the amount of data E [ D ] that the target vehicle can receive from the road infrastructure in one cycle is calculated in step 2a)I]The calculation formula is as follows:
wherein: m is the number of intervals divided according to the communication rate, and the communication rate of the M intervals can be expressed as: w ═ W1,W2,...,WM}，τiIndicating the time the target vehicle lingers in the ith zone.
3. The prefetch-based file collaborative downloading method according to claim 1, wherein the target vehicle is calculated to be [0, t ] in the step 2b)]Average amount of data D that can be downloadedaveThe calculation formula is as follows:
wherein: p is a radical of0Indicating a probability of at least one cooperating vehicle being present in a coverage area of the roadway; p is a radical ofcRepresenting the probability that c cooperative vehicles exist in the coverage area of the road arrangement at the same time; m represents that the road arrangement coverage area is divided into M areas; wiThe transmission rate of the ith area in the routing coverage range is represented; lambda [ alpha ]wIs a parameter when an inverted vehicle arrives in poisson; t isiIs the target vehicle's sojourn time in the ith zone; t is the time required by the target vehicle to drive through two adjacent roads at a constant speed, and is also the cycle time.
4. The prefetch-based file collaboration download method as recited in claim 1, wherein the registering of the vehicle characteristic information in step 1 is performed using a three-dimensional array < idi,vi,tiIs represented by, wherein idiIs an identifier of the vehicle, viIs the speed of the vehicle, tiIs the current time.
5. The file collaborative downloading method based on prefetching as in claim 1, wherein in step 1, the arrival rate of the vehicle randomly selecting the communication range where the target vehicle enters the nearest road infrastructure is: assuming that vehicles arrive in an approximate poisson process and the traffic flow densities in one direction are all constant rho, the arrival rate lambda of the vehicles is:
wherein: v. offIs the maximum speed, p, allowed for the vehiclejamIs the traffic jam density at which the traffic flow tends to stop.
6. The prefetch-based file collaboration downloading method as claimed in claim 1, characterized in that said step 1b) is embodied to broadcast its own idle state information when the router has served a request; when a node with a downloading requirement listens the idle state information, request information is sent to the router.
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| CN109495561B (en) * | 2018-11-07 | 2022-03-15 | Oppo广东移动通信有限公司 | Application program downloading method, device, terminal and storage medium |
| CN109600715B (en) * | 2018-11-29 | 2020-11-20 | 哈尔滨工程大学 | Internet of vehicles V2X communication auxiliary file downloading method |
| CN110519345B (en) * | 2019-08-14 | 2022-04-08 | 杭州师范大学 | Internet of vehicles information safety cooperation downloading method based on multi-assistance vehicle autonomous selection |
| CN112566070B (en) * | 2020-12-09 | 2022-08-09 | 重庆邮电大学 | Cooperative data transmission method in Internet of vehicles environment |
| CN117376848A (en) * | 2023-12-07 | 2024-01-09 | 南昌大学 | Road city sensing system based on expressway vehicle network |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103491186A (en) * | 2013-09-30 | 2014-01-01 | 中国石油大学(华东) | Vehicle internet assisting downloading method based on dynamic time slot |
| CN104601667A (en) * | 2014-12-23 | 2015-05-06 | 武汉大学 | Gapless vehicle networking assist downloading method |
| CN105430616A (en) * | 2015-12-04 | 2016-03-23 | 深圳北航新兴产业技术研究院 | Data scheduling method based on vehicle collaboration in urban scene |
| CN105871831A (en) * | 2016-03-28 | 2016-08-17 | 江苏大学 | Data fragmenting and downloading service method in vehicular network |
-
2017
- 2017-09-29 CN CN201710910561.9A patent/CN107786941B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103491186A (en) * | 2013-09-30 | 2014-01-01 | 中国石油大学(华东) | Vehicle internet assisting downloading method based on dynamic time slot |
| CN104601667A (en) * | 2014-12-23 | 2015-05-06 | 武汉大学 | Gapless vehicle networking assist downloading method |
| CN105430616A (en) * | 2015-12-04 | 2016-03-23 | 深圳北航新兴产业技术研究院 | Data scheduling method based on vehicle collaboration in urban scene |
| CN105871831A (en) * | 2016-03-28 | 2016-08-17 | 江苏大学 | Data fragmenting and downloading service method in vehicular network |
Non-Patent Citations (1)
| Title |
|---|
| MobTorrent:A Framework for Mobile Internet Access from Vehicles;BinBin Chen;《IEEE INFOCOM 2009》;20090425;摘要，正文第3节 * |
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