阅读说明：本技术 一种基于车载网络的数据下发方法及装置 (Data issuing method and device based on vehicle-mounted network ) 是由 徐连明 王莉 费爱国 崔鹤文 田泽宇 魏青 于 2021-06-07 设计创作，主要内容包括：本发明提供一种基于车载网络的数据下发方法及装置,包括：利用纠删码编码技术将热点内容编码成多个分片,对分片进行冗余编码获取多片内容分片,并分别缓存至簇中的各VU；接收车载网络中目标VU对热点内容的加载请求,向目标VU发送内容分片,控制其它k’辆VU将各自缓存的内容分片发送给目标VU,直至目标VU根据接收到的k个内容分片解码生成热点内容。本发明提供的基于车载网络的数据下发方法及装置,利用RSU对热点资源进行缓存,并采用分布式编码缓存技术将内容进行编码分片以缓存至各VU中,保证了内容传输的鲁棒性,提升了缓存节点空间利用率,减小了网络负荷和回程链路压力,在缓解基站压力的同时降低车辆获取内容资源的时延。(The invention provides a data issuing method and a device based on a vehicle-mounted network, comprising the following steps: encoding the hot spot content into a plurality of fragments by using an erasure code encoding technology, performing redundant encoding on the fragments to obtain a plurality of content fragments, and respectively caching the content fragments to each VU in the cluster; receiving a loading request of a target VU to hot spot content in a vehicle-mounted network, sending content fragments to the target VU, and controlling other k' vehicle VUs to send the cached content fragments to the target VU until the target VU decodes the received k content fragments to generate the hot spot content. According to the data issuing method and device based on the vehicle-mounted network, the hot spot resources are cached by the RSU, and the content is coded and partitioned by adopting a distributed coding caching technology to be cached into each VU, so that the robustness of content transmission is ensured, the space utilization rate of a cache node is improved, the network load and the pressure of a return link are reduced, and the time delay of a vehicle for acquiring the content resources is reduced while the pressure of a base station is relieved.)

1. A data issuing method based on a vehicle-mounted network is characterized by comprising the following steps:

coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment;

the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene;

receiving a loading request of any target VU in the vehicle-mounted network to the hot spot content, and sending a content fragment to the target VU;

after the road side unit RSU sends the content fragments with the number of k-k 'to the target VU, if the sending of the content fragments to the target VU is stopped, other k' VUs send the content fragments cached respectively to the target VU until the target VU decodes the k received content fragments to generate the hot spot content.

2. The vehicle-mounted network-based data delivery method according to claim 1, before caching the content segments to the vehicle users VU in a cluster, further comprising:

dividing all VUs in the cluster into strong users and weak users according to channel conditions;

pairwise grouping the strong users and the weak users to obtain a plurality of NOMA user pairs; each of said NOMA user pairs consisting of a strong user and a weak user;

the strong users in the pair of NOMA users are regarded as NOMA strong users, the weak users in the pair of NOMA users are regarded as NOMA weak users, and the remaining strong or weak users which cannot be grouped are regarded as V2I users.

3. The vehicle-mounted network-based data delivery method according to claim 1, wherein the caching the content segments to each vehicle user VU in one cluster respectively comprises:

sending the content slices to each of the NOMA strong users, each of the NOMA weak users, and each of the V2I users using a V2I link.

4. The vehicle-mounted network-based data delivery method according to claim 3, wherein the controlling other k 'vehicle VUs to send the content fragments cached by the other k' vehicle VUs to the target VU comprises:

when the target VU is a NOMA strong user or a NOMA weak user, any other NOMA strong user or any other NOMA weak user sends the content fragments to the target VU in a NOMA communication mode, and the total number of any other NOMA strong user and any other NOMA weak user is k';

accordingly, in the case that the target VU is a V2I user, the roadside unit RSU continues to transmit the content fragment to the target user using the V2I link.

5. The data issuing method based on the vehicle mounted network according to claim 3, characterized by further comprising:

the method comprises the following steps that (1) between NOMA strong users and NOMA weak users in the same sub-cluster, interactive transmission of content fragments is carried out in a frequency spectrum multiplexing mode;

the number of VUs in the sub-cluster is greater than or equal to 2.

6. The vehicle-mounted network-based data delivery method according to claim 1, wherein before encoding any hot content into multiple segments by using erasure coding technology, performing redundant coding on all segments to obtain multiple content segments, and caching the content segments to each vehicle user VU in one cluster, the method further comprises:

constructing a data issuing optimization model by taking the minimized total time delay as a target;

solving the data issuing optimization model to obtain the condition of the optimal VU forming user pair, beta_gThe formed user pairs are aligned to an optimal power distribution factor matrix, an optimal transmitting content fragmentation condition matrix between VUs, an optimal RB distribution condition matrix, an optimal transmission power distribution matrix in the V2V process, the number of k and the number of k';

wherein, beta_gIndicating that the g-th user pair is a NOMA user pair.

7. The vehicle-mounted network-based data delivery method according to claim 6, wherein the solving of the data delivery optimization model comprises:

obtaining position information of each VU and a maximum value of transmission power

Dividing all VUs in a cluster into strong users and weak users according to channel conditions, calculating the sum of communication time delays of NOMA (non-orthogonal multiple access) users formed by each strong user and each weak user, and determining the weight of each strong user and each weak user according to the communication time delays of all strong users and the communication time delays of all weak users;

based on Hungarian algorithm, matching x by taking the strong and weak user weight values under the condition that the traversing rate of all VUs and the maximum user pair are met as the maximum user weight values₁(ii) a Matching x according to the user maximum weight₁Calculating the time delay t of each VU₁；

Two groups of same VUs are used as two point sets, and when the two point sets are the same VU, the edge weight value is assigned to be infinite; when the two point sets are different VUs, setting the edge weight value as the time delay of the two VUs for transmitting the message;

obtaining minimum weight matching x by using many-to-many matching algorithm₂To determine all VU receive delays and the smallest V2V link pair case;

taking all VUs as a set, and calculating the time delay when any two VUs in the set multiplex resources; if the time delay is larger than the sum of the time delays of the VUs when the resource is used independently, constructing an edge between points corresponding to every two VUs, and thus obtaining a traditional graph;

coloring the traditional graph based on a hypergraph coloring algorithm, wherein two points with edges are colored in different colors, and points corresponding to the same resource are colored in the same color;

according to the coloring result, acquiring the resource reuse condition x₃And according to x₃Calculating V2V communication time delay t of each VU₂；

According to t₁、t₂Calculating the total time delay t of all VUs in a sending-down stage and a communication stage;

method for solving the maximum value based on single variable, combining x₁、x₂、x₃To P_V2VAnd P_RSUThe optimization is performed such that the total time delay t is minimized.

8. A data issuing device based on a vehicle-mounted network is characterized by comprising:

the system comprises a content issuing unit, a data processing unit and a data processing unit, wherein the content issuing unit is used for encoding any hot content into a plurality of fragments by using an erasure code encoding technology, performing redundant encoding on all the fragments to obtain a plurality of content fragments, and respectively caching the content fragments to each vehicle user VU in one cluster; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene;

a first data issuing unit, configured to receive a loading request of any target VU in the vehicle-mounted network for the hot content, and send a content fragment to the target VU, so that the target VU decodes the content fragment to generate the hot content;

and the second data issuing unit is used for controlling other k ' vehicle VUs to send the content fragments cached by the other k ' vehicle VUs to the target VU if the content fragments are stopped being sent to the target VU after the RSU sends the content fragments to the target VU in the number of k-k ' until the target VU generates the hot spot content according to the received k content fragments by decoding.

9. A non-transitory computer-readable storage medium, on which a computer program is stored, wherein the computer program, when being executed by a processor, implements the steps of the data distribution method based on the vehicular network according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, on which a computer program is stored, wherein the computer program, when being executed by a processor, implements the steps of the data distribution method based on the vehicular network according to any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of communication, in particular to a data issuing method and device based on a vehicle-mounted network.

Background

With the popularization of public transportation, more and more families with private cars are provided, and cars even play an indispensable role in the life of the present invention. However, with the dramatic increase in the number of vehicles, existing roadway infrastructure has not been able to meet these vehicle user demands. When a large number of vehicle nodes send requests for the same hot content, the phenomenon of repeated downloading of resources occurs, and wireless link resources are wasted. Also, repeated transmission of large amounts of hot content can further increase network load and backhaul link pressure, causing peak network congestion. Compared with a mobile handheld device end, the roadside unit and the vehicle have better data storage capacity, content files are cached on the devices, data transmission efficiency can be effectively improved, and pressure of a return link is reduced.

Therefore, in the prior art, hot spot resources are cached on surrounding vehicles and roadside units in advance, so that the hot spot resources and the roadside units can realize close-range content sharing, thereby alleviating the pressure of a base station and reducing the time delay of the vehicles for acquiring the content resources.

However, due to rapid changes in the topology of the vehicle-mounted network and the quality of the communication link, complete content may not be completely transmitted in a short time, so that a user cannot completely download a large-volume file.

Disclosure of Invention

Aiming at the problems in the prior art, the embodiment of the invention provides a data issuing method and device based on a vehicle-mounted network.

In one aspect, the present invention provides a data issuing method based on a vehicle-mounted network, including: coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene; receiving a loading request of any target VU in the vehicle-mounted network to the hot spot content, and sending a content fragment to the target VU; after the road side unit RSU sends the content fragments with the number of k-k ' to the target VU, if the sending of the content fragments to the target VU is stopped, other k ' vehicle VUs are controlled to send the content fragments cached by the other k ' vehicle VUs to the target VU until the target VU generates the hot spot content according to the received k content fragments.

On the other hand, the invention also provides a data issuing device based on the vehicle-mounted network, which comprises: the system comprises a content issuing unit, a data processing unit and a data processing unit, wherein the content issuing unit is used for encoding any hot content into a plurality of fragments by using an erasure code encoding technology, performing redundant encoding on all the fragments to obtain a plurality of content fragments, and respectively caching the content fragments to each vehicle user VU in one cluster; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene; a first data issuing unit, configured to receive a loading request of any target VU in the vehicle-mounted network for the hot content, and send a content fragment to the target VU, so that the target VU decodes the content fragment to generate the hot content; and the second data issuing unit is used for controlling other k ' vehicle VUs to send the content fragments cached by the other k ' vehicle VUs to the target VU if the content fragments are stopped being sent to the target VU after the RSU sends the content fragments to the target VU in the number of k-k ' until the target VU generates the hot spot content according to the received k content fragments by decoding.

In another aspect, the present invention further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement any of the above steps of the data distribution method based on the in-vehicle network.

In another aspect, the present invention further provides a non-transitory computer readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements the steps of the data issuing method based on the vehicular network according to any one of the above.

According to the data issuing method and device based on the vehicle-mounted network, the hot spot resources are cached by the RSU, and the content is coded and partitioned by adopting a distributed coding caching technology to be cached into each VU, so that the robustness of content transmission is ensured, the space utilization rate of a cache node is improved, the network load and the pressure of a return link are reduced, and the time delay of a vehicle for acquiring the content resources is reduced while the pressure of a base station is relieved.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic flow chart of a data issuing method based on a vehicle-mounted network according to the present invention;

FIG. 2 is a diagram of a distributed content delivery scenario assisted by a non-orthogonal multiple access technique according to the present invention;

FIG. 3 is a schematic diagram of a process for solving a user pairwise problem based on a matching theory according to the present invention;

FIG. 4 is a schematic diagram of a process for solving a V2V link by using a matching theory according to the present invention;

FIG. 5 is a schematic diagram of a process for solving resource allocation using graph coloring algorithm provided by the present invention;

FIG. 6 is a flow chart of a resource allocation and user pairing scheme based on matching theory provided by the present invention;

FIG. 7 is a schematic diagram of the bisection algorithm provided by the present invention;

FIG. 8 is a schematic structural diagram of a data issuing device based on a vehicle-mounted network according to the present invention;

FIG. 9 is a schematic diagram of the distribution of Vus and RSU provided by the present invention;

fig. 10 is one of the schematic diagrams of the average delay of all users according to the number of users provided by the present invention;

FIG. 11 is one of the schematic diagrams of the average traversal rate of all users according to the number of users provided by the present invention;

FIG. 12 is a schematic diagram illustrating the variation of the average traversal rate of all users with the number of users and the upper and lower limits;

FIG. 13 is a schematic diagram of the variation of the average delay of all users with the number of users and the encoding parameters provided by the present invention;

FIG. 14 is a graph illustrating the variation of average spectral efficiency with the number of users provided by the present invention;

FIG. 15 is a second schematic diagram of the distribution of Vus and RSU provided by the present invention;

fig. 16 is a second schematic diagram illustrating the variation of the average delay of all users with the number of users provided by the present invention;

FIG. 17 is a second schematic diagram illustrating the variation of the average traversal rate of all users with the number of users according to the present invention;

fig. 18 is a schematic structural diagram of an electronic device provided by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The existing Vehicle networking data is generally issued by caching hot spot resources on a Road Side Unit (RSU) and issuing the hot spot resources to a Vehicle User (VU) by the RSU, but due to rapid changes of Vehicle network topology and communication link quality, complete content may not be completely transmitted in a short time.

The data issuing method based on the vehicle-mounted network considers that a distributed coding caching technology is introduced, content is firstly coded and fragmented by utilizing erasure codes before content data is issued, then the coded content fragments are stored in a vehicle cache node in advance, when a content request vehicle (called as a target VU) initiates a request for certain hot spot content, a plurality of peripheral VUs send the respective cached content fragments to the target VU so as to assist the target VU to realize downloading of the hot spot content together. After the content requesting vehicle obtains a certain number of content slices, the complete content can be obtained by decoding.

In view of this, the two stages of content deployment (deployment of content slices) and content slice transmission (transmission of content slices) are crucial for vehicle encoding caching.

In the content deployment stage, when the content fragments are transmitted by adopting the traditional Orthogonal Multiple Access (OMA), the content fragments need to be sequentially transmitted to different content cache vehicle nodes, and the problem of low spectral efficiency and energy efficiency exists.

Secondly, in the content transmission phase, how the vehicle selects a communication link to acquire content fragmentation and how to plan resource usage in the two phases also has a great influence on the performance of the system.

Finally, the decision problem in the whole process takes time, and how to make the target VU make a quick decision is also an important problem.

Currently, many research works only consider the deployment of content fragments, but do not consider the content fragment issuing and transmitting processes at the same time, and do not consider the time problem consumed by the decision problem.

Therefore, the invention is based on the whole process of content deployment and content transmission, and comprehensively considers the communication condition of the VUs in the two processes and reasonably manages resources so that all the VUs in a scene can recover to obtain the required complete content as soon as possible.

The following describes a data issuing method and device based on a vehicle-mounted network according to an embodiment of the present invention with reference to fig. 1 to 18.

Fig. 1 is a schematic flow diagram of a data issuing method based on a vehicle-mounted network, as shown in fig. 1, including but not limited to the following steps:

step 101: coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU stores only one piece of content clips.

The cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene;

step 102: and the RSU receives a loading request of any target VU in the vehicle-mounted network to the hot spot content and sends a content fragment to the target VU.

Step 103: after the RSU sends the content fragments to the target VU by the road side unit RSU, if the sending of the content fragments to the target VU is stopped, the RSU controls other k' VUs to send the content fragments cached by the RSU to the target VU until the target VU generates the hot spot content according to the received k content fragments.

The invention assumes that there are U RSUs with the buffer function in the scene, and defines the index of the RSUs asMeanwhile, a certain number of VUs exist in a scene.

In step 101, in each time slot, according to the position of each VU and the request situation of the hot spot content in the scene, all VUs are divided into a plurality of clusters (assuming that vehicles in each cluster are traveling in the same direction), and all RSs (r & s) are used for determining the hot spot content in the sceneThe U stores all hot point contents required by all VUs in the scene, and defines the hot point contents asSuppose that the size of the f-th content is C_f。

The hot spot content is generally larger content such as a road condition high-definition map, each RSU issues content for all VUs in a current cluster, and it is assumed that the number of VUs in a vehicle cluster served by the u-th RSU at a certain time slot is K_u。

Because of the mobility of vehicles, issuing complete hot content to a target VU within the communication coverage range of the RSU is often difficult to realize, so that at the RSU side, the RSU firstly divides the hot content into k pieces by using an erasure code coding technology, then obtains n pieces of content fragments by redundant coding, and then issues the content fragments to any target VU needing content downloading in a scene by using a NOMA technology and combining a V2I communication technology according to the communication link condition.

After receiving the content fragments, the target VU sends the content fragments cached by itself to the target VU (or to other VUs at the same time) according to the content fragment conditions owned by itself and the surrounding VUs (i.e. the set formed by multiple VUs), and acquires the required content fragments from other VUs, if a certain target VU has different content fragments with k pieces, the required complete content can be recovered by decoding.

The erasure code coding technology may be (n, k) Maximum Distance Separable (MDS) coding technology, and specifically, n pieces of redundant content fragments are obtained by coding the content and stored in different VUs, so that the cache size of each vehicle user for one content is reduced, and meanwhile, any target VU that needs to download the content can obtain the original content by decoding only by obtaining any k pieces of the n pieces of content fragments.

Specifically, in step 102, a certain target RSU issues content fragments to VUs in its corresponding cluster, and for any target VU, since the target VU is always in a running state, it is assumed that after receiving k-k' content fragments sent by the RSU, it no longer belongs to the cluster where the target RSU is located, and the target RSU terminates sending content fragments to the target VU (or fails to send), and then the process proceeds to step 103.

In step 103, after the RSU sends content fragments to the target VU in a number of k-k ', if the sending of content fragments to the target VU is terminated, the base station controls other k' VUs to send the content fragments cached by the respective VUs to the target VU until the target VU receives k content fragments in total. At this time, the target VU may generate the hot content according to the received k content slice decoding.

According to the data issuing method based on the vehicle-mounted network, the hot spot resources are cached by the RSU, and the content is coded and partitioned by adopting a distributed coding caching technology to be cached in each VU, so that the robustness of content transmission is ensured, the space utilization rate of a cache node is improved, the network load and the pressure of a return link are reduced, and the time delay of a vehicle for acquiring the content resources is reduced while the pressure of a base station is relieved.

Based on the content of the foregoing embodiment, as an optional embodiment, before caching the content segments at each vehicle user VU in one cluster, the method further includes:

dividing all VUs in the cluster into strong users and weak users according to channel conditions;

pairwise grouping the strong users and the weak users to obtain a plurality of NOMA user pairs; each of said NOMA user pairs consisting of a strong user and a weak user;

the strong users in the pair of NOMA users are regarded as NOMA strong users, the weak users in the pair of NOMA users are regarded as NOMA weak users, and the remaining strong or weak users which cannot be grouped are regarded as V2I users.

The data issuing method based on the vehicle-mounted network also considers the problem of low frequency spectrum utilization rate caused by the fact that a vehicle singly uses a special frequency spectrum in the communication process, and therefore the NOMA technology is adopted to assist in issuing the data.

Fig. 2 is a scene diagram of distribution of content delivery under the assistance of the non-orthogonal multiple access technology provided by the present invention, as shown in fig. 2, it is assumed that, in a time slot, VUs in the same cluster apply for the same hot content. The complete communication process is shown in fig. 1, and the (4, 3) coding is taken as an example in fig. 2, and the complete process is shown.

Firstly, considering the channel condition, dividing the VUs in each cluster into three types of users, namely a NOMA strong user, a NOMA weak user and a V2I user, and then sending the content fragments to the NOMA strong user, the NOMA weak user and the V2I user in different modes according to the classification condition of the VUs.

Then, the VUs in the scene shares its own content shards to other VUs according to the received content shard condition and the V2V link condition between the surrounding VUs, and receives other content shards from other VUs to recover the complete content through decoding, so that the VUs in the whole cluster can obtain the required content.

(1) Regarding the content issuing stage (hereinafter referred to as the first stage):

the invention firstly considers using NOMA technology in the process of content sending, namely, how to divide Vus in a cluster into the following parts in the process of content sending: the NOMA strong user, the NOMA weak user and the V2I user, so that the RSU issues the content fragments to each VU in different ways.

Specifically, consider first the u-th RSU and the corresponding cluster, consider K in the cluster_uVehicle VU, notedRemember h_iFor the channel power gain of the RSU sending messages to the ith VUs, considering that the channel obeys rayleigh distribution, the channel power gain can be expressed as:

h_i＝δ_id_i ^-α；

wherein d is_iDistance, δ, of RSU to ith Vus_iFor this purpose, the channel fading coefficients from RSU to i-th VUs, α is the path loss exponent.

According to the channel condition, dividing the VUs in the cluster into two parts of strong user and weak user, such as the VU with the channel intensity larger than a certain threshold valueDividing the VU less than or equal to the threshold value into strong users, and dividing the VU less than or equal to the threshold value into weak users, which are respectively marked asWhereinSatisfy M + N ═ K_u. There are two paired methods between the strong and weak users:

a) NOMA pairs: the strong and weak users, which are respectively the strong and weak users in the NOMA pair, i.e. operating in NOMA strong user mode and NOMA weak user mode, can use the same spectrum resources in the presence of interference.

b) And virtual pair: i.e., when the number of strong users is greater than the number of weak users, or the number of weak users is greater than the number of strong users, there will be some pairs of VUs with another type of VUs that there is no way for some VUs to form NOMA pairs, and the remaining strong or weak users that cannot be grouped are treated as V2I users (as V2I users operating in V2I mode), i.e., the V2I users receive content fragments directly from the RSU over the V2I link.

Based on the content of the foregoing embodiment, as an optional embodiment, the caching the content segments to each vehicle user VU in one cluster respectively includes:

sending the content slices to each of the NOMA strong users, each of the NOMA weak users, and each of the V2I users using a V2I link.

Further, the controlling other k 'vehicle VUs to send the content fragments cached by the other k' vehicle VUs to the target VU includes:

when the target VU is a NOMA strong user or a NOMA weak user, any other NOMA strong user or any other NOMA weak user sends the content fragments to the target VU in a NOMA communication mode, and the total number of any other NOMA strong user and any other NOMA weak user is k'; accordingly, in the case that the target VU is a V2I user, the roadside unit RSU continues to transmit the content fragment to the target user using the V2I link.

In addition, the content fragments are interactively sent by adopting a multiplexing frequency spectrum mode between NOMA strong users and NOMA weak users in the same sub-cluster; the number of VUs in the sub-cluster is greater than or equal to 2.

Note the bookThe index of user pairs formed for strong and weak users,and satisfies G ═ max { M, N }.

Assuming that a frequency spectrum is divided into Resource Blocks (RBs) with the same bandwidth, and the total bandwidth of the frequency spectrum resources is B, assuming that, in a data distribution stage (a first stage), a V2I link does not multiplex the frequency spectrum, the frequency spectrum resources are divided into G RBs, and the bandwidth of each RB is B/G. Remember h_g，SAnd h_g，WThe channel power gains of the communication links between the RSU and the strong and weak users in the g-th user pair respectively are as follows:

h_g，S＝δ_g，Sd_g，S ^-α (1a)

h_g，W＝δ_g，Wd_g，W ^-α (1b)

wherein d is_g，S、d_g，WRespectively the distance, delta, from the RSU to the strong or weak user in the g-th user pair_g，S、δ_g，WThe channel fading coefficients of the strong and weak users in the RSU to g-th user pairs respectively and obey rayleigh fading.

Definition of gamma_g，SAnd gamma_g，WThe received Signal-to-Noise ratios (SINRs) of the strong and weak users in the g-th user pair respectively, the Signal-to-Interference plus Noise Ratio (SINR) from the RSU to the strong and weak users in the g-th user pair for transmitting content fragmentation is respectively as follows:

wherein beta is_gE (0, 1/2) is the power allocation factor, P, in the g-th user pair_RSUIs the total power, σ, of the RSU in sending messages to each user pair²Is Additive White Gaussian Noise (Additive White Gaussian Noise AWGN).

When the g-th user pair is a virtual pair, if the VU in the g-th user pair is a strong user, the beta value is beta_gIf VU is weak, then β is equal to 1_g0. The rates of the strong and weak users in the g-th NOMA pair are respectively:

defining variablesRepresenting whether the VU is in the g-th user pair (the variable X is the case that the VU forms the user pair), if the q-th VUs are in the g-th user pair, X_q，g1, otherwise x_q，g0, wherein

Assuming that the required content in the cluster is f, after (n, k) encoding, the size of each content slice is C_fK, in order to fully utilize the performance superiority of the content issued by the RSU, the k-k' piece of content fragmentation is issued in the issuing process, and meanwhile, the issuing process needs to be at t₁And is finished within time.

(2) Regarding the V2V communication phase (hereinafter referred to as the second phase):

taking the scenario shown in fig. 2 as an example, the whole process of content delivery and sharing is described with (4, 3) coding as an example (i.e. n is 3, k is 3), and as can be seen from fig. 2, in the content delivery process, the VUs selects different modes of receiving content slices, i.e. NOMA strong user, NOMA weak user, and V2I user, where NOMA strong user, NOMA weak user, and V2I user all receive content slices from RSU.

After the content is sent out, when the content sharing process is started, because the target VU already receives k-k ' content fragments from the RSU, the complete content can be recovered by decoding only by receiving the content fragments from another k ' VUs having fragments different from the k ' content fragments.

Considering that the f-th hot spot content required by the VUs in the cluster is coded by using erasure codes to obtain n pieces of content fragments, which are marked as n pieces of content fragmentsRecording variablesThe storage condition of Vus to content fragment after the content fragment is issued to RSU, if the q-th Vus receives the content fragment j from RSU, y_qj1, otherwise y_qj0, wherein

It is assumed that each VU can acquire a desired piece of content shard to any different VU. Recording variablesRepresenting the situation of sharing content segments among the VUs, if the q-th VUs transmit content segments to the i-th VUs, z_qi1, otherwise z_qi0, wherein

When the q-th vehicle VUs transmit the content clips to the i-th vehicle VUs, the content clips are recorded in h_qiThe channel power gain when the content slices are transmitted to the ith vehicle VUs for the qth vehicle VU can be expressed as:

h_qi＝δ_qid_qi ^-α (4)

wherein d is_qiIs the distance between the q-th and i-th vehicle Vus, δ_qiIs the channel fading coefficient between the qth vehicle VUs and the ith vehicle VUs.

Optionally, in the data delivery method based on the vehicle-mounted network provided by the present invention, in order to improve the spectrum utilization, it is assumed that when the content sharing stage V2V is in communication, the VUs and the content delivery stage use the same spectrum resource, and the spectrum resource is subdivided into RBs with equal bandwidth, and in the V2V process, the RBs can be multiplexed between the VUs.

Considering that all VUs in the current cluster are clustered again according to the interference relationship among the VUs, the obtained VUs in the same sub-cluster use the same RB, wherein the number of the VUs in each sub-cluster is not more than 2, the VUs are assumed to be divided into R sub-clusters in total, and the sub-clusters are recorded as a setDefine variable A ∈ {0, 1}^Q×RRepresenting the situation that the VUs are divided into sub-clusters, if the q-th VUs are divided into the r-th sub-cluster when the content fragments are sent by the q-th VUs, a_qr1, otherwise a_qr＝0。

Definition of gamma_qiThe received SINR when the q-th VUs transmits the content fragment to the i-th VUs may be expressed as:

wherein p is_qiFor the transmission power, g, when the q-th VU transmits content slices to the i-th VU_q′i′For the interference channel power gain to the i ' th vehicle VUS when the q ' th vehicle VUS sends the content fragmentation to the i ' th vehicle VUS, then p_q′i′The power at which the q 'th vehicle VU transmits the content slices to the i' th vehicle VU.

Therefore, the rate at which the ith vehicle VU receives content slices is:

based on the content of the foregoing embodiment, as an optional embodiment, before encoding any hot content into multiple segments by using erasure coding technology, performing redundant coding on all the segments to obtain multiple content segments, and caching the content segments to each vehicle user VU in one cluster, the method further includes:

constructing a data issuing optimization model by taking the minimized total time delay as a target; solving the data issuing optimization model to obtain the condition of the optimal VU forming user pair, beta_gThe formed user pairs are aligned to an optimal power distribution factor matrix, an optimal transmitting content fragmentation condition matrix between VUs, an optimal RB distribution condition matrix, an optimal transmission power distribution matrix in the V2V process, the number of k and the number of k'; wherein, beta_gIndicating that the g-th user pair is a NOMA user pair.

Specifically, the present invention utilizes traversal rate to evaluate communication delay. To minimize the maximum value of all VUs communication delays in both phases, the problem can be modeled. Note T_i(pair)For the communication delay of the ith VU in the first stage, T_i(pair)The expression of (a) is:

accordingly, the data rate of the ith VU in the first stage can be defined as R_i(pair)And the communication time delay of the ith VU in the second stage is T_i(V2V)The data rate is R_i(V2V). In the first stage, the VU has already received the content slices of k-k 'slices from the RSU, so in the second stage, it only needs to receive one content slice from each of the other VUs of k' to decode and obtain the complete content, then T_i(V2V)The expression of (a) is:

to a maximum extentMinimizing the total time delay of all VUs in two stages, the invention models the problem as

P_RSU＞P_V2V (9l)

k-k′≥k′ (9m)

Specifically, in formula (9), the case where the user pair is composed of VUs is optimized; optimizing variablesThe storage condition of VU to content fragment after transmitting content fragment for RSU, if q-th VU receives content fragment j from RSU, y_qj1, otherwise y_qj0; the optimization variable beta is composed of_gForming a user centering power distribution factor matrix; the optimization variable Z is a matrix for indicating the situation of transmitting content fragments between VUs; the optimization variable A is an RB allocation condition matrix; the optimization variable P is the transmission power allocation matrix in the V2V process.

Specifically, the constraint (9a) of the above optimization problem indicates that each VU can only be in one user pair; constraint (9b) indicates that there is at most one strong user in each user pair; constraint (9c) indicates that there is at most one weak user in each user pair; the constraint (9d) indicates that if the g-th user pair is a NOMA pair, the transmission power allocation factor is greater than 0 and less than 1/2; constraint (9e) indicates that the first stage content delivery phase is to be at t₁Is finished within time; the constraint (9f) indicates that the second stage V2V communication stage is to be at t₂Is finished within time; the constraint condition (9g) indicates that each VU can only be in one sub-cluster when transmitting the content fragments; the constraint (9h) indicates that there are at most two Vus in each sub-cluster; the constraint (9i) indicates that the VU of the second stage V2V process has a transmit power less than P_V2V(ii) a Constraint (9j) tableIndicating that the VU can receive the content fragments from k' users in the second stage so as to obtain enough content fragments for decoding to obtain complete content; the constraint (9k) representing the emission power P of the first phase VU_RSUEmission power P of VU associated with the second stage V2V process_V2VThe sum ofThe constraint (91) representing the emission power P of the first phase VU_RSUIs larger than the transmission power P of VU of the second stage V2V process_V2V(ii) a The constraint (9m) indicates that the number of content fragments delivered in the first phase is greater than the number of content fragments received in the second phase, so as to ensure that the VU can obtain the required number of fragments.

As an alternative embodiment, after the data delivery optimization model shown in formula (9) is constructed, the invention decomposes the problem related to formula (9), including but not limited to the following steps:

obtaining position information of each VU and a maximum value of transmission powerDividing all VUs in a cluster into strong users and weak users according to channel conditions, calculating the sum of communication time delays of NOMA (non-orthogonal multiple access) users formed by each strong user and each weak user, and determining the weight of each strong user and each weak user according to the communication time delays of all strong users and the communication time delays of all weak users; based on Hungarian algorithm, matching x by taking the strong and weak user weight values under the condition that the traversing rate of all VUs and the maximum user pair are met as the maximum user weight values₁(ii) a Matching x according to the user maximum weight₁Calculating the time delay t of each VU₁(ii) a Two groups of same VUs are used as two point sets, and when the two point sets are the same VU, the edge weight value is assigned to be infinite; when the two point sets are different VUs, setting the edge weight value as the time delay of the two VUs for transmitting the message; obtaining minimum weight matching x by using many-to-many matching algorithm₂To determine all VU receive delays and the smallest V2V link pair case; calculate all VUs as a setTime delay when any two VUs in the set multiplex resources; if the time delay is larger than the sum of the time delays of the VUs when the resource is used independently, constructing an edge between points corresponding to every two VUs, and thus obtaining a traditional graph; coloring the traditional graph based on a hypergraph coloring algorithm, wherein two points with edges are colored in different colors, and points corresponding to the same resource are colored in the same color; according to the coloring result, acquiring the resource reuse condition x₃And according to x₃Calculating V2V communication time delay t of each VU₂(ii) a According to t₁、t₂Calculating the total time delay t of all VUs in a sending-down stage and a communication stage; method for solving the maximum value based on single variable, combining x₁、x₂、x₃To P_V2VAnd P_RSUThe optimization is performed such that the total time delay t is minimized.

Specifically, the solution can be performed by dividing equation (9) into two sub-problems according to content distribution (first stage) and content sharing (second stage).

First, considering the content delivery process, a first sub-problem can be obtained:

s.t. constraint (9a) to constraint (9e) (12a)

In sub-problem one, one can first maximize by optimizing X and β

When X to exp (θ), P is constant, one can obtain:

wherein the content of the first and second substances,is an exponential integration function. Assuming strong user channel fading complianceRayleigh distribution with mean lambda_SWeak user channel fading obeys Rayleigh distribution and has an average value of lambda_WDefinition of μ_g，S＝λ_Sd_g，S ^-α/σ²，μ_g，W＝λ_Wd_g，W ^-α/σ². When rayleigh fading, the traversal rates of strong and weak users in the g-th user pair are respectively:

the total traversal rate of the g-th user pair is r_g＝r_g，S+r_g，W。

If the g-th user pair is a virtual pair and the VU in the g-th user pair is a strong user, then beta_gIf VU in this virtual pair is a weak user, β is 1_g＝0。

As can be seen from the reference, when the channel fading follows rayleigh distribution, in order to reduce the complexity of solving the traversal rate, the upper and lower limits of the traversal rate may be relaxed, and are defined as follows:

wherein:

therefore, the invention can obtain the following upper and lower limits of the strong user respectively:

the upper and lower limits of the weak user are respectively:

FIG. 3 is a schematic diagram of a process for solving the user pairwise problem based on the matching theory according to the present invention, as shown in FIG. 3, the weights between the strong and weak users are calculated according to the above equations (18a) - (18b) and the equations (19a) -19 b; then, a user pair is formed between users by using a matching algorithm to solve the formula (12) by using a matching theory.

Further, the present invention considers the process of sharing content fragmentation (second phase), which can be called problem two:

s.t. constraint (9f) -constraint (9j) (19a)

In sub-problem two, one may first go through optimization Z, A, P to maximize

When allocating spectrum resources for VUs, a graph coloring algorithm may be used, first, an edge is established according to a data rate condition when two VUs simultaneously use the same spectrum resource, when the qth VU sends a message to the ith VU, the same resource block is used as the qth VU sends a message to the ith VU, and when the qth VU sends a message to the ith VU, if the data rate is less than a threshold, an edge is constructed between the qth VU and the qth 'VU, and the data rates of the qth VU and the qth' VU are respectively:

according to the reference, when X₁～exp(α₁)，X₂～exp(α₂) Then, one can obtain:

whereinAssuming channel power gainThe data rates of the qth VU and the qth' VU can be written as:

fig. 4 is a schematic diagram of a process for solving a V2V link by using a matching theory provided by the present invention, fig. 5 is a schematic diagram of a process for solving resource allocation by using a graph coloring algorithm provided by the present invention, which is used as a weight when matching a V2V link and an edge weight relationship in a conventional graph, and the matching theory shown in fig. 4 is used to solve a V2V link, and the graph coloring algorithm shown in fig. 5 is used to solve a resource allocation situation, so as to solve formula (19).

FIG. 6 is a flow chart of the resource allocation and user pairing scheme based on matching theory provided by the present invention, and in summary, the present invention utilizes a one-to-one matching algorithm for solving equation (12), and then solves equation (19) with a graph coloring algorithm.

Fig. 7 is a schematic diagram of the bisection algorithm provided by the present invention, and as shown in fig. 7, the whole solving process includes:

firstly, looking the strong users and the weak users as two point sets, and calculating the traversal rate sum of the user pairs of each strong user and each weak user in the process of forming the user pairs. When solving the traversal rate sum, since R_g，SIs associated with beta_gMonotonically increasing, R_g，WIs associated with beta_gMonotonically decreasing, with the sum of traverse rates being with β_gMonotonically increasing, the present invention can use the bisection algorithm shown in FIG. 7 for β_gOptimized and then optimized by optimizing beta_gAnd maximizing the sum of the traversal rates in the g-th user pair, and taking the sum of the traversal rates as an edge weight between two users.

The Hungarian algorithm is then used to find the maximum weight match to decide on the NOMA pairwise case.

Further, consider the VUs set as two point sets, each point set containing all VUs, assuming that one set is the set of transmitting users and the other set is the set of receiving users. Since each receiving user needs to receive content fragments from k' sending users, which is a many-to-many problem, a many-to-many matching algorithm can be used to find the minimum weight matching to decide the V2V communication link formation condition.

And calculating the traversal rate when the q-th VU and the q '-th VU multiplex the resource block based on the V2V link forming condition, and if the traversal rate is smaller than a threshold value, determining that an edge exists between the q-th VU and the q' -th VU, so as to construct the traditional graph.

Then, a graph coloring algorithm is used for solving so as to obtain the multiplexing situation of power between VUs. In the above process, the invention divides the power into P_RSUAnd P_V2VThen, according to the pairing situation of the user, the link forming situation of V2V and the resource multiplexing situation, the method of using single variable to find the maximum value is used to perform P under the constraint condition (9k) to the constraint condition (9m)_V2V、P_RSUAnd optimizing to minimize the communication time delay of the Vus in the whole process.

Fig. 8 is a schematic structural diagram of a data issuing device based on a vehicle-mounted network according to the present invention, as shown in fig. 8, the data issuing device mainly includes: a content issuing unit 81, a first data issuing unit 82, and a second data issuing unit 83, wherein:

the content issuing unit 81 is mainly configured to encode any hot content into multiple segments by using erasure coding technology, perform redundant coding on all the segments to obtain multiple content segments, and cache the content segments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene.

The first data issuing unit 82 is mainly configured to receive a loading request of any target VU in the vehicle-mounted network for the hot spot content, and send a content fragment to the target VU, so that the target VU decodes the content fragment to generate the hot spot content.

The second data issuing unit 83 mainly controls other k ' vehicle VUs to send the content fragments cached by the other k ' vehicle VUs to the target VU if the sending of the content fragments to the target VU is terminated after the road side unit RSU sends the number of the content fragments to the target VU is k-k ', until the target VU generates the hot spot content by decoding the received k content fragments.

It should be noted that, during specific operation, the data issuing device based on the vehicle-mounted network according to the embodiment of the present invention may execute the data issuing method based on the vehicle-mounted network according to any of the foregoing embodiments, which is not described in detail in this embodiment.

In order to fully show the beneficial effects of the data issuing method and device based on the vehicle-mounted network, the invention verifies the performance of the invention through experimental simulation results.

Specifically, in fig. 6, the hungarian matching algorithm is adopted, the HK algorithm and the GS algorithm are used as the reference in the simulation verification, the total time delay and the running time of all vehicle users using the three matching algorithms are compared based on different vehicle distribution scenes, and the advantages and the disadvantages of the different matching algorithms in the scene considered in this chapter are compared.

When the matching algorithm is used for the first time, the two matching parties are a strong channel Vus and a weak channel Vus. When the GS algorithm is used, the preference list of the strong channel Vus to the weak channel Vus is set as the transmission time delay of the strong channel VU when the strong VU and the weak VU form user time synchronization; the preference list of the strong channel Vus by the weak channel Vus is set as the transmission time delay of the weak channel VU when the strong VU and the weak VU form user time synchronization.

For the HK algorithm, because the edge weight value relationship of the two matched parties is not considered, and only the connectivity of the two parties is considered, the edge weight value between each strong VU and each weak VU is set to be a logic value 1, which represents that the two sides can be communicated. Aiming at the minimization of the sum of weights of the Hungarian algorithm, when the Hungarian algorithm is used, the sum of the transmission time delays of strong and weak users is set as the sum of the edge weights between the strong channel Vus and the weak channel Vus.

When the matching algorithm is used for the second time, both matching parties are all VUs, when the GS algorithm is used, if the VUs on the two sides are the same VU, the preference is set to be negative infinity, the matching is represented as not capable of being matched, if the VUs on the two sides are not the same VU, the preference is set to be transmission delay, and the preference list matrixes of the VUs on the two sides are in a transposition relation. When the HK algorithm is used, edge weight values between different VUs on two sides are set to be logic values 1 which represent that the VUs can be communicated, and logic values 0 are set between the same VUs which represent that the VUs cannot be communicated. When the Hungarian algorithm is used, the edge weight values between different VUs on two sides are set as transmission time delay, the edge weight values between the same VUs are set to be negative infinity, and the edge weight values cannot be matched.

In order to simplify the experimental process, the invention considers the condition that only one cluster exists in the scene, and respectively aims at different maximum values of the transmitting powerPerforming comparison while settingPath loss factor α is 3 and white gaussian noise power is σ²The data rate threshold of the vehicle user forming the NOMA pair is the data rate when the vehicle user works in the OMA state, the threshold of the data rate of the vehicle user in the V2V process is the data rate when the vehicle user does not multiplex resource blocks with other users, the current result is (3, 2) encoding (namely n is 3, k is 2), and k' is 1, and the simulation result and the simulation analysis are as follows:

when the RSUs are distributed on one side of the lane:

fig. 9 is a schematic diagram of VUs and RSU distribution provided by the present invention, considering that the width of a lane is 20m and the length is 80m, and the RSU is located at the middle position of one side of the lane, wherein considering the vehicle size and the safety distance between vehicles, considering that the distance of the center of each vehicle is 8m long and 5m wide, and the RSU is located at the coordinate (40, 0) position, in which case the vehicle and RSU distribution is as shown in fig. 9.

Fig. 10 is a schematic diagram of changes in average time delay of all users along with the number of users provided by the present invention, as shown in fig. 10, a triangular dotted line is a case of the hungarian matching algorithm used by the present invention, an open circle is a case of using the GS matching algorithm, a solid circle is a case of using the HK matching algorithm, and a solid line represents a corresponding current time delayIn the case of (1), the dotted line bar represents the correspondingThe situation of time.

From simulation analysis, it can be seen that the Hungarian algorithm is superior to other matching algorithms in use in the proposed scheme. In thatUnder the condition, the Hungarian algorithm is averagely reduced by 14.4% compared with the GS algorithm in the aspect of average time delay, and is averagely reduced by 39.7% compared with the HK algorithm in the aspect of average time delay. In thatUnder the condition, the Hungarian algorithm is averagely reduced by 19.9% compared with the GS algorithm in average time delay, and is averagely reduced by 50.3% compared with the HK algorithm in average time delay.

Fig. 11 is one of schematic diagrams illustrating changes in average traversal rates of all users according to the number of users provided by the present invention, and as shown in fig. 11, the hungarian algorithm used by the present invention is superior to other matching algorithms. In thatUnder the condition, the Hungarian algorithm is improved by 4.7% relative to the GS algorithm in the aspect of the traversal rate, and is improved by 58.9% relative to the HK algorithm in the aspect of the traversal rate. In thatUnder the condition, the Hungarian algorithm is improved by 6.8% relative to the GS algorithm in the aspect of the traversal rate, and is improved by 83.9% relative to the HK algorithm in the aspect of the traversal rate.

FIG. 12 is a schematic diagram illustrating the variation of the average traversal rate of all users with the number of users and the upper and lower limits, as shown in FIG. 12, by comparing the case of using the upper and lower limits to calculate the traversal rate in the first stage, the simulation experiment of this time usesThe triangle lines adopt a Hungarian matching algorithm and do not use upper and lower limits; the hollow round line is the case of using the Hungarian matching algorithm and using the upper limit in the first stage; the solid round bar is the case when the hungarian matching algorithm is used, and the case when the lower limit is used. As can be seen from simulation analysis, the results of using the relaxed upper and lower limits are not much different from those of the unused upper and lower limits. The result using the lower bound to calculate the traversal rate differs by 4.6% compared to the result without the upper and lower bounds. The upper bound calculation was used to calculate the traversal rate with a 3.7% difference compared to the results without the upper and lower bounds.

Fig. 13 is a schematic diagram of changes in average time delay of all users along with the number of users and the coding parameters, which are provided by the present invention, and the hungarian algorithm is used in the simulation experiment. Wherein the triangle lines representIn the case of k 2 and k' 1, the open circle representsIn the case where k is 4 and k' is 1, the solid circle representsk 2, k' 0, i.e. only the first stage V2I communication, the solid lines represent the corresponding onesIn the case of (1), the dotted line represents the correspondingThe situation of time.

From simulation analysis, it can be seen that the delay is minimal when k is 2 and k' is 1. In thatIn the case where k is 2 or k ' is 1, the delay time is reduced by 19.6% with respect to the case where k is 4 or k ' is 1, and the delay time is reduced by 32.6% with respect to the case where k is 2 or k ' is 0. In thatIn the case where k is 2 or k ' is 1, the delay time is reduced by 22.7% with respect to the case where k is 4 or k ' is 1, and the delay time is reduced by 37.0% with respect to the case where k is 2 or k ' is 0.

Fig. 14 is a schematic diagram of the change of the average spectral efficiency with the number of users, the average spectral efficiency is represented by a ratio of the total spectral efficiency to the number of users, and the hungarian algorithm is used in the simulation experiment. The triangle line represents the average spectral efficiency issued by the first stage using the NOMA technology, the solid circle line represents the average spectral efficiency issued by the first stage using the OMA technology, and the solid line represents the corresponding current timeIn the case of (1), the dotted line represents the correspondingThe situation of time.

From simulation analysis, it is known that the NOMA issue is more advantageous than the OMA issue in terms of average spectral efficiency. In thatUnder the condition, the average spectral efficiency of the NOMA issuing is improved by 4.9 percent compared with that of the OMA issuing. In thatUnder the condition, the average spectral efficiency of the NOMA issuing is improved by 4.7 percent compared with that of the OMA issuing.

Two) when the RSUs are equally distributed on both sides of the lane:

the vehicle and RSU distribution in this case is shown in fig. 14.

Fig. 15 is a schematic diagram of another VUs and RSU distribution provided by the present invention, considering that the width of the lane is 20m and the length is 80m, the RSU is located at the middle position of the lane, considering that the vehicle size and the safety distance between the vehicles, considering that the distance between the centers of each vehicle is 8m and the width is 5m, and the RSU is located at the coordinate (40, 10) position, in which case the vehicle and RSU distribution is as shown in fig. 15.

Fig. 16 is a schematic diagram of the change of the total time delay of all users along with the number of users provided by the present invention, as shown in fig. 16, a triangular dotted line is a case of the hungarian matching algorithm used by the present invention, an open circle is a case of using the GS matching algorithm, a solid circle is a case of using the HK matching algorithm, and a solid line represents a corresponding current time delayIn the case of (1), the dotted line bar represents the correspondingThe situation of time.

Analysis from simulationIt is known that the use of the hungarian algorithm in the proposed scheme is superior to other matching algorithms. In thatUnder the condition, the Hungarian algorithm is averagely reduced by 10.1% compared with the GS algorithm in average time delay, and is averagely reduced by 42.1% compared with the HK algorithm in average time delay. In thatUnder the condition, the Hungarian algorithm is averagely reduced by 16.4% compared with the GS algorithm in average time delay, and is averagely reduced by 54.0% compared with the HK algorithm in average time delay.

Fig. 17 is a schematic diagram of the change of the average traversal rate of all users along with the number of users provided by the present invention, and as shown in fig. 17, the use of the hungarian algorithm is superior to other matching algorithms. In thatUnder the condition, the Hungarian algorithm is improved by 4.5% relative to the GS algorithm in the traversing speed, and is improved by 54.1% relative to the HK algorithm in the traversing speed. In thatUnder the condition, the Hungarian algorithm is improved by 6.4% relative to the GS algorithm in the aspect of the traversal rate, and is improved by 75.8% relative to the HK algorithm in the aspect of the traversal rate.

In summary, compared with the results of different vehicle distributions, it can be seen that the difference in the position of the RSU has a significant effect on the total delay in the first stage, because the vehicle and RSU distributions have no effect on the V2V link, and only have an effect on the distance between the vehicle and the RSU, that is, the effect on the link for issuing content segments by the RSU is greater, so the resulting trends of the two vehicle distributions are the same.

Fig. 18 is a schematic structural diagram of an electronic device provided in the present invention, and as shown in fig. 18, the electronic device may include: a processor (processor)810, a communication Interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication Interface 820 and the memory 830 communicate with each other via the communication bus 840. The processor 810 may call logic instructions in the memory 830 to perform a data delivery method based on an in-vehicle network, the method including: coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene; receiving a loading request of any target VU in the vehicle-mounted network to the hot spot content, and sending a content fragment to the target VU; after the road side unit RSU sends the content fragments with the number of k-k ' to the target VU, if the sending of the content fragments to the target VU is stopped, other k ' vehicle VUs are controlled to send the content fragments cached by the other k ' vehicle VUs to the target VU until the target VU generates the hot spot content according to the received k content fragments.

In addition, the logic instructions in the memory 830 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In another aspect, the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, when the program instructions are executed by a computer, the computer being capable of executing the data issuing method based on the vehicular network provided by the above methods, the method including: coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene; receiving a loading request of any target VU in the vehicle-mounted network to the hot spot content, and sending a content fragment to the target VU; after the road side unit RSU sends the content fragments with the number of k-k ' to the target VU, if the sending of the content fragments to the target VU is stopped, other k ' vehicle VUs are controlled to send the content fragments cached by the other k ' vehicle VUs to the target VU until the target VU generates the hot spot content according to the received k content fragments.

In still another aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program is implemented by a processor to execute the in-vehicle network-based data issuing method provided in the foregoing embodiments, and the method includes: coding any hot content into a plurality of fragments by using an erasure code coding technology, performing redundant coding on all the fragments to obtain a plurality of content fragments, and caching the content fragments to each vehicle user VU in one cluster respectively; each VU only stores one piece of content fragment; the cluster is determined by dividing all VUs according to the positions of all VUs in the vehicle-mounted network and the request information of all VUs for hot spot contents in the scene; receiving a loading request of any target VU in the vehicle-mounted network to the hot spot content, and sending a content fragment to the target VU; after the road side unit RSU sends the content fragments with the number of k-k ' to the target VU, if the sending of the content fragments to the target VU is stopped, other k ' vehicle VUs are controlled to send the content fragments cached by the other k ' vehicle VUs to the target VU until the target VU generates the hot spot content according to the received k content fragments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.