Cross-operator v2v video content sharing method based on consortium blockchain

Abstract

A cross-operator V2V video content sharing method based on alliance blockchain, first constructs a double-layer alliance blockchain framework, maintains and verifies the consensus of the content transaction ledger in the chain, and manages the identity of participants and stores and executes smart contracts between the chains. Under this framework, combined with scalable video coding technology SVC, an optimal vehicle group selection algorithm based on comprehensive matching degree is proposed, which maximizes the reduction of service cost under the constraints of vehicle reputation, V2V connection duration and achievable transmission rate. At the same time, a cross-operator V2V contract calling mechanism is adopted. By issuing rewards to the base station, the base station is encouraged to upload transaction data quickly, thereby reducing the contract calling delay and avoiding transaction interruption due to the excessive response time of cross-operator video content transactions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of network, and particularly relates to a cross-operator V2V video content sharing method based on alliance block chain. BACKGROUND

[0002] The fifth generation wireless network (5G, 5th Generation Mobile Communication Technology) brings unprecedented connection speed and performance to the Internet of Vehicles (IoV, Internet of Vehicles), promoting the rapid development of video applications such as automatic driving environment perception and road entertainment. Due to the scarcity of radio spectrum, it is difficult for 5G base stations to support large-scale vehicle-mounted video services. Another problem is that the frequent switching of vehicle-to-infrastructure (V2I, Vehicle To Infrastructure) connection caused by high-speed vehicle movement reduces the stability of video services. Vehicle-to-vehicle (V2V, Vehicle to Vehicle) video content delivery helps to alleviate the storage and communication burden of fixed infrastructure, expand the video content transmission range, and reduce the content delivery delay [4].

[0003] The goal of cross-operator V2V content sharing is to build an open, secure and agile vehicle interaction architecture, break down the barriers between operators, and deeply integrate vehicle content services of different operators through blockchain and V2X technology, so as to improve the flexibility and coverage of vehicle content services and reduce the communication pressure of network infrastructure.

[0004] However, a large number of transaction records will be generated in multi-operator V2V video content distribution. If the traditional single-block chain architecture is adopted, the distributed nodes of the system will bear a large storage and query burden

[11] . Compared with public chains, the data management strategy of alliance chains has customizability, which is reflected in that the data processing capacity and the number of nodes participating in transaction verification can be upgraded and expanded according to demand. With this advantage, alliance chains can provide customized data support capabilities for cross-operator V2V video content delivery. In addition, the alliance chain architecture helps to manage the multi-party trust problem under collaborative V2V video transactions [3]. Unlike public chains, users accessing the alliance chain need to be authenticated, which provides a prerequisite for realizing mutual trust between on-chain members. The tamper-proof nature of alliance block chains ensures the traceability of security incidents, thereby regulating the transaction behavior between participants [5, 6].

[0005] Although alliance chains have many potential advantages in solving multi-operator V2V video content transactions, there are still some challenging problems to be solved:

[0006] (1) The base station and the vehicle can only transact with the video published by their own operator. The transaction between vehicles of different operators cannot be verified, and it is difficult to realize value exchange across operators.

[0007] (2) Compared with single-operator V2V video services, cross-operator V2V video services provide more choices for content requesters. How to choose the optimal decision scheme to maximize the service cost savings for requesters becomes one of the problems to be considered.

[0008] (3) The transaction request between vehicles of different operators depends on the base station for uploading and contract calling. If the base station cannot assist the vehicle in cross-operator transaction uploading and verification within the effective time, it will inevitably lead to the interruption of subsequent content transactions.

[0009] Due to the high mobility and network dynamics in the Internet of Vehicles, V2V video content delivery is prone to transmission interruption, unstable video quality, and low cache hit rate. Literature [5] proposes an enhanced user datagram protocol that uses unequal protection of video frame types to improve video transmission quality in vehicle-mounted networks. Literature [6] proposes an effective video streaming mechanism that reduces interference by selecting the smallest subset of relay vehicles and achieves high-quality video propagation in VANET. Literature [7] proposes an adaptive video streaming scheme based on scalable layered video coding technology (SVC, Scalable Video Coding) to support video services in highway scenarios. Through vehicle relaying, requesters can obtain video data from adjacent cars or multi-hop paths to the base station.

[0010] The alliance chain architecture can be designed and customized according to actual needs, and can provide flexible architectural support for the Internet of Vehicles. Literature [8] proposes a collaborative credential management scheme based on blockchain for anonymous authentication in space-air-ground integrated Internet of Vehicles. This scheme builds an alliance blockchain between service providers to collaboratively manage user subscriptions for authenticated network access and service charging. Literature [9] designs a two-layer distributed software-defined network technology (SDN, Software Defined Networks) controlled vehicle edge computing network architecture, and realizes the trusted sharing of network topology information between distributed SDN controllers based on alliance chain, thereby preventing information leakage. A blockchain-based V2V transaction model is proposed in literature

[10] , which is based on the idea of forming an alliance of electric vehicles to conduct V2V power transactions in specific locations, and designs an alliance entry strategy and matching mechanism for V2V power transactions. SUMMARY

[0011] Video content service in vehicle network is one of the main applications to improve passenger travel experience, but there are problems of large resource consumption, long transmission duration, strict quality of service (QoS, Quality of Service) requirements and difficulty in realizing safe and reliable content sharing of vehicles belonging to different operators. Therefore, the present application proposes a cross-operator V2V video content distribution method based on alliance chain, aiming to break the barriers between different operators. In order to improve the efficiency of data management, the present application builds a double-layer alliance block chain based on the block chain framework. The main design is to maintain the content transaction ledger and consensus verification within the chain, and to manage the identity of participants and store and execute smart contracts between chains.

[0012] Under this framework, the present application designs an optimal vehicle group selection algorithm based on comprehensive matching degree based on scalable video coding technology (SVC, Scalable Video Coding). The algorithm can minimize service cost under the constraints of vehicle reputation, V2V connection duration and achievable transmission rate.

[0013] At the same time, a cross-operator V2V contract calling mechanism is proposed. By issuing rewards to the base station, the base station is encouraged to upload transaction data quickly, thereby reducing contract calling delay and avoiding transaction interruption due to excessive response length of cross-operator video content transaction. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic diagram of an alliance (block) chain model;

[0015] Figure 2 is a schematic diagram of information interaction between the main chain and the sub-chain;

[0016] Figure 3 is a schematic diagram of vehicle group selection (case 1);

[0017] Figure 4 is a schematic diagram of vehicle group selection (case 2);

[0018] Figure 5 is a schematic diagram of cross-operator transaction processing example;

[0019] Figure 6 is a schematic diagram of the change of base station upload reward;

[0020] Figure 7 is a schematic diagram of average delivery delay comparison under different schemes;

[0021] Figure 8 is a schematic diagram of service cost comparison under different methods;

[0022] Figure 9 is a schematic diagram of service cost comparison under different methods;

[0023] Figure 10 is an average service fee cost schematic diagram in different modes;

[0024] Figure 11 is a service fee cost and delay ratio schematic diagram. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] 1SUMMARY

[0027] In view of the transaction gap problem between different operators, the present application proposes a cross-operator V2V video content distribution method based on alliance chain, which realizes safe V2V content sharing and value exchange between different operators. The main contributions include:

[0028] First, in view of the problem (1) mentioned in the background art, a multi-chain architecture of alliance chain is designed, which reduces the data redundancy of the alliance chain system while realizing cross-operator value exchange.

[0029] Second, in view of the problem (2) mentioned in the background art, an optimal vehicle group selection algorithm based on comprehensive matching degree is developed, which helps the requester to find the optimal decision among many alternative vehicles, and maximizes the service cost saving on the basis of meeting the video service quality.

[0030] Third, in view of the problem (3) mentioned in the background art, a cross-operator V2V contract calling mechanism is proposed. By issuing rewards to the base station, the base station is encouraged to upload transaction data quickly. Thus, the contract calling delay is reduced, and the transaction interruption caused by the too long response time of cross-operator video content transaction is avoided.

[0031] Security analysis and simulation experiments prove the feasibility and superiority of the proposed method.

[0032] 2Design of multi-operator cooperative architecture based on alliance chain

[0033] Figure 1 The designed cross-operator V2V architecture is shown, which is mainly divided into content delivery layer, information management layer and transaction consensus layer.

[0034] 1) Content delivery layer: composed of vehicles and base stations with cache and communication capabilities, responsible for realizing cross-operator video content delivery. The function of this layer is to complete transaction uploading while ensuring stable transmission of video content in the cross-operator V2V transaction environment.

[0035] 2) Information management layer: This layer is responsible for identity authentication and security check of vehicles to ensure that the vehicles meet the requirements of safety and communication protocols. In addition, this layer also needs to record and store the release information of video content and the results of transaction execution to prevent video content from being tampered with.

[0036] 3) Transaction consensus layer: responsible for consensus verification of cross-operator V2V video content transactions to realize value exchange between vehicles of different operators. The transaction consensus layer stores the smart contract for executing content transactions and the vehicle reputation value that needs to be frequently read and written for transaction verification. The nodes participating in transaction consensus must reach a consensus on content delivery to ensure that all transactions are trustworthy.

[0037] 2.1 Hierarchical multi-chain structure design

[0038] As shown in Figure 1 , the proposed architecture contains two types of chains:

[0039] 1) Operator sub-chain: Under the cross-operator V2V architecture, video content delivery will generate a large number of transaction records. Each operator maintains a sub-chain to record the video content and related transactions published by itself, realizes content-centered transaction data shunt storage, and reduces the storage burden of the cross-operator transaction main chain. At the same time, operators can also quickly query content flow information through transaction records in the sub-chain.

[0040] 2) Cross-operator transaction main chain: The main chain is co-built by the interest alliance composed of multiple operators, responsible for the deployment of smart contracts and the recording of reputation values. Operators set and deploy smart contracts according to alliance rules. Video content and contracts are authorized by operators to the main chain and broadcasted to the Internet of Vehicles environment through base stations. V2V video content transactions need to reach transaction consensus on the main chain, thereby ensuring the global consistency of transaction processing results. After the completion of content transaction initiated by the vehicle, the reputation value of the transaction party is updated to the main chain. At the same time, the content transaction result verified through the main chain will be stored in the sub-chain corresponding to the transaction content through cross-chain interaction.

[0041] 2.2 Cross-chain data trusted interaction

[0042] In order to ensure the authenticity of value exchange, a verification mechanism based on signature and Merkle hash tree is designed. At the same time, the main chain and the sub-chain are equipped with a proof module to verify the authenticity of cross-chain interaction information, which is used to verify the identity of the node and the source of the data, and realizes the trusted query and update of the data.

[0043] As shown in Figure 2 , taking the transaction query from the main chain to the sub-chain as an example, the information interaction process mainly includes the following steps:

[0044] Step 1: When a node needs to query the transaction information in the subchain of operator A, it can send a transaction record query by calling the smart contract in the main chain. The identifier of the query is q.

[0045] Step 2: The proof module of the main chain assigns an authorization identifier ε to the query, and then packages and signs the relevant information as Sign(q, ε) and sends it to the subchain of operator A.

[0046] Step 3: After receiving the information Sign(q, ε), the proof module on the subchain of operator A is responsible for verifying the authenticity of the signature information Sign(q, ε).

[0047] Step 4: If the authentication is passed, the query request q will be queried in the data record of the subchain A.

[0048] Step 5: After obtaining the query result Info(q), in order to prove the authenticity of the query result, the subchain of operator A needs to provide additional proof information, denoted as P(Info(q)), representing the Merkle verification path of Info(q) in the subchain A. And send the signed query result Sign(Info(q), P(Info(q))) to the main chain.

[0049] Step 6: After Sign(Info(q), P(Info(q))) is verified by the proof module of the main chain, the smart contract will obtain the transaction query result Info(q).

[0050] 3 Cross-operator V2V video content distribution method

[0051] This section designs a cross-operator V2V video content distribution method.

[0052] First, for the problem of video content distribution in vehicle networking between vehicles and base stations, a fair reward allocation strategy is developed.

[0053] Second, the cross-operator minimum service cost problem is modeled and a solution algorithm based on comprehensive matching degree is designed.

[0054] Finally, a contract invocation strategy for cross-operator transactions is designed to verify transactions between vehicles of different operators.

[0055] 3.1 Fair reward allocation

[0056] Through SVC technology, video content n is encoded into M layers, and the set of video layer indexes is denoted as The video quality is related to the number of video layers. is denoted as the set of video contents in the system, where is the index of the video content. c n,mThe m-th layer is represented as content n. The utility that a content requester can obtain is proportional to the popularity and size of the received video. When the requester receives video layer c from vehicle j... n,m At that time, the utility gained is calculated as follows:

[0057]

[0058] Where f n,m Content c n,m popularity, s n,m c is obtained by the requester from vehicle j. n,m size, Let χ,δ be the average size of the video layer in the vehicle-to-everything (V2X) network. τ and τ are adjustable parameters.

[0059] The set of neighboring vehicles of vehicle i The set of vehicle indices carrying video content n is represented as follows: Requester i via vehicle After obtaining video content n, the utility generated is calculated as follows:

[0060]

[0061] The service fees a vehicle can earn are positively correlated with its credit score. Vehicle i from Get c n,m Service fee generated κ j,n,m Calculated as:

[0062]

[0063] Where t i,j,n,m This indicates that the base station is for vehicle j to upload video layer c. n,m The time point of the transaction, t i ' ,j,n,m For vehicles The time point at which the transaction request is initiated, r j p represents the reputation value of vehicle j. n,m It is the video layer c n,m The price λ is an adjustable parameter.

[0064] Another possibility is that the neighboring vehicle did not have a cache. n,m At this point, vehicle i has to obtain c from base station b at a higher cost. n,m The service fee generated is calculated as follows:

[0065]

[0066] in, This is an adjustable parameter.

[0067] 3.2 Problem Modeling and Algorithm Design

[0068] To facilitate understanding, this invention constructs a case scenario (see Figure 3 Vehicles 1, 2, and 3 belong to operator A, and vehicles 4 and 5 belong to operator B. Assume that the reputation of these vehicles meets the requirements, and each vehicle has sufficient communication resources to deliver only one video layer at a time. Vehicles 1-5 are all adjacent to vehicle i and all carry the video layer information for video c1. Assume that vehicle i of operator A initiates a quality level υ request for video c1. i,1 =4 requests. In the case of V2V video content distribution limited to within the operator, vehicle 1, vehicle 2, and vehicle 3 become c 1,1 c 1,2 c 1,3 Content providers, such as Figure 3 As shown. Due to limitations in caching and communication resources, c 1,4 Lacking a content provider for the vehicle, vehicle i must obtain c from the base station. 1,4 It is evident that the single-carrier model limits the improvement of V2V performance. To broaden the range of video content providers, it is necessary to explore a multi-carrier collaborative V2V video content distribution mechanism.

[0069] Next, we will model the vehicle selection problem under a multi-operator collaborative model. Let a be a binary decision variable. i,j,n,m =1 means vehicle i selects vehicle. Provide video layer c n,m For a vehicle i to request content n, the content provider selection problem is modeled as follows: Essentially, it involves solving the problem under video quality constraints. Minimize service fees as much as possible.

[0070]

[0071] Subject to:

[0072]

[0073]

[0074] t i,j,n,m ≤t′ i,j,n,m +t0 (5c)

[0075] a i,j,n,m ∈{0,1} (5d)

[0076] If vehicle i cannot obtain the required information via V2V, it must resort to V2I. In this case, Service cost reaches the highest level If all the video layers can be obtained by relying on the V2V mode, The objective function is transformed into

[0077]

[0078] At this time, the problem is equivalent to finding a set of vehicles that can minimize the service cost from .

[0079] Constraint (5a) ensures that the providers of c n,m meet the minimum reputation requirements, α is used to adjust the reputation value, β is the weight factor of content popularity, r j represents the reputation value of vehicle j. Under constraint (5b), content provider j must complete the delivery of c i,j in the period d n,m that can be sustainedly connected, where w j represents the transmission rate that vehicle j can achieve. Before the video content transaction, the content provider vehicle needs to upload the transaction request to the main chain through the base station to call the transaction contract. If the base station uploads the transaction for a long time (calculated as t i,j,n,m -t′ i,j,n,m ) exceeds the specified time limit t0, it will cause the subsequent vehicle content transaction to be terminated. If vehicle is selected as the provider of c n,m , then t i,j,n,m must satisfy (5c).

[0080] In order to solve the problem This section designs a vehicle group selection algorithm based on comprehensive matching degree, see Algorithm 1, and the specific implementation details are as follows:

[0081] (1) Global variables Min and are used to record the total service cost required to obtain content n and the optimal content provider set, respectively.

[0082] (2) Update the set of selectable content providers c n,m according to the reputation value, sustainable connection time, and delay of uploading transactions (line 2). If the quality requirements of content requester i have been met (line 3), compare the current total service cost with Min (line 4). If the current total service cost is smaller, update Min and record the current decision scheme.

[0083] (3) When the quality requirements of content requester i have not been met, judge the number of vehicles of the current layer selectable content providers. If c n,m has no provider (line 8), it needs to be provided by the base station.

[0084] (4) If cn,m If there are vehicles available as content providers, iterate through all possible decision options. Try making an available vehicle the content provider and update the temporary decision (line 14). For c n,m After selecting the content provider vehicle, the next content provider in the next layer is selected (line 16). When backtracking through other decision options, some variables need to be restored to their previous state (lines 17-18).

[0085] (5) Finally, after searching all possible strategies, the solution that minimizes service fees will be updated to...

[0086]

[0087] Within the proposed cross-carrier framework, vehicles belonging to carrier B can also provide the necessary content to vehicle i of carrier A. For ease of understanding, Algorithm 1 will be applied... Figure 3 In the scenario shown, the calculation results are as follows: Figure 4 As shown, vehicles 1, 5, 4, and 3 form c. 1,1 c 1,2 c 1,3 c 1,4 The content provider. Vehicles do not need to obtain content through V2I, saving service fees.

[0088] 3.3 Contract calls for cross-carrier transactions

[0089] Before the transaction contract is executed, the vehicle, acting as the content provider, needs to upload transaction information via a base station. This section proposes an incentive strategy to encourage the base station to expedite the uploading of transaction requests, thereby preventing transaction interruptions.

[0090] Assume base station b is a vehicle Uploaded video layer c n,m Transaction information. The contribution of this base station to this video request is calculated as follows:

[0091]

[0092] When base station b uploads transaction requests for content n from other video layers, its contribution can continue to accumulate.

[0093] Once the transaction is completed, the reward amount that base station b, which assisted in uploading the transaction data, can receive from the operator is calculated as follows:

[0094]

[0095] where g is an adjustable parameter. The shorter the interval time for the base station to upload transactions, the higher the reward that can be obtained. If the base station fails to upload the transaction to the main chain within the effective time limit to, no income can be obtained.

[0096] The transaction processing flow in the cross-operator scenario is explained below. It is assumed that the vehicle j of operator A caches the video layer c n,m from operator B When the vehicle i is provided with the content c n,m , the submitted transaction needs to go through the processing steps as shown in Figure 5 :

[0097] Step ①: The vehicle j, as the content provider, signs the contract address information sent by the vehicle i c n,m and uploads the transaction signature to the base station of operator A;

[0098] Two signatures are represented, the first signature uses the private key K S of i, and the second signature uses the private key K i of j S ; i

[0099] Step ②: The base station of operator A uploads the transaction request initiated by both parties to the main chain;

[0100] Step ③: The proof module in the main chain acquires the signature information, calls and executes the corresponding smart contract

[0101] Step ④: The main chain, as the blockchain that maintains the global reputation value, updates the reputation value of the vehicles;

[0102] Step ⑤: After the main chain completes the transaction verification, it transmits the transaction result to the subchain of operator B, thereby realizing the content-centric transaction record storage;

[0103] Step ⑥: The subchain of operator B verifies the credibility of the result sent by the main chain through the proof module;

[0104] Step ⑦: After the transaction verification is completed, the operator updates and stores the transaction record related to c n,m .

[0105] The transaction contract calling process is shown in Algorithm 2. After the requester i initiates the transaction with the content provider j, the content provider j sends the transaction information with the signature to the base station, which uploads the transaction to the main chain. After the related contract in the main chain is successfully called, the pre-deduction is automatically performed on the accounts of the two parties of the transaction. After the transaction consensus verification is completed, the smart contract will issue rewards to the participants according to the collected transaction scores and transaction proof vouchers. The execution result of the smart contract is submitted to the subchain, so as to realize content-centered transaction storage.

[0106]

[0107] 4Security analysis

[0108] · Trusted cross-chain information transmission: the present application encrypts and verifies the interaction information through the proof module.

[0109] If the cross-chain information is tampered with, the method can find untrusted data through signature and proof information. · Prevention of double-spend fraud: there is a risk of double payment in cross-operator V2V video transactions. Attackers can

[0110] initiate content transactions belonging to different subchains at the same time to obtain improper benefits. The pre-deduction locking mechanism based on the smart contract can prevent vehicles from initiating video requests for content published by different operators at the same time using the same handling fee, thereby destroying the fairness of transactions.

[0111] · Prevention of content tampering: vehicles in cross-operator transactions can implant malicious links in content

[0112] outside the jurisdiction of their operators to obtain illegal benefits. Under the content-centered cross-operator transaction ledger maintenance, the transaction record will be stored in the subchain where the video content is published after consensus verification on the main chain. Even if the video content is tampered with by vehicles of other operators, content tracing can be performed through the transaction ledger of the subchain.

[0113] · Prevention of transaction forgery: when vehicle j provides content c n,m to vehicle i, both parties must sign the contract address related to c n,m , namely , as a transaction request voucher. At the same time, the path voucher upload based on the Merkle verification mechanism can prevent vehicles from maliciously brushing scores through forged transaction records for cross-operator V2V transactions.

[0114] 5Simulation experiment and result analysis

[0115] The simulation experiment simulates a vehicle networking environment where multiple operators coexist. In order to obtain a more realistic simulation effect, the simulation randomly generates 100 video contents according to the literature

[15] , and each video content uses SVC to achieve a video quality of M=4. Each vehicle caches the content with higher popularity in the 100 video contents. At the same time, the content request will be randomly initiated according to the Zipf distribution. The values of the simulation parameters λ、 g are set to 0.0135, 0.0001, 0.015, and 0.15, respectively.

[0116] To facilitate the analysis of the impact of the proposed scheme on video content delivery delay and service cost, this section selects the following two video delivery methods:

[0117] • Baseline Method 1

[12] : is a collaborative video delivery method, but the optional range of its content providers is limited to vehicles under the same operator.

[0118] • Baseline Method 2

[13]

[14] : is a non-collaborative video transmission method. The requester selects a unique vehicle to provide all the required video content.

[0119] 5.1 Analysis of upload rewards across base stations under different operators

[0120] This subsection examines the change of the transaction forwarding reward obtained by the base station with the upload interval time when the contribution of the transaction upload is 1 / 4, 1 / 2, 1 respectively (the definition of contribution is given in formula (6)). It can be known from Figure 6 that the higher the contribution of the base station to a single video request, the higher the reward it can obtain. In addition, timely uploading of the transaction request of the vehicle can also bring higher income to the base station. The upload interval time of the transaction is inversely proportional to the upload reward obtained by the base station. If the upload interval time approaches the time limit t0 that the video transaction can tolerate, the reward will approach 0.

[0121] 5.2 Influence of cache space on average delivery delay

[0122] Figure 7The average delivery delay of different methods is compared when the video quality requirement is 4. It is assumed that the average cache size of vehicles is in the range of [5, 35] GBs, and the size of video content is in the range of [0.2, 0.8] GBs. The video content requested by vehicles has been uniformly cached in each vehicle, and the requester does not need to obtain the content from the base station. According to the different cache space of video content, the number of alternative providers of video content will also be different. Large cache space is conducive to improving cache hit rate, thereby reducing the average delivery delay. The benchmark method 1 has lower average delivery delay than the benchmark method 2. This is because the benchmark method 2 relies on a single vehicle to deliver the entire video, which takes a long time. Using the benchmark method 1, the requester can obtain different video layers from multiple adjacent vehicles, thereby shortening the video delivery time. The proposed method has lower average delivery delay than the benchmark method 1. This is because when the requester needs to obtain a certain content, the number of alternative content providers under a single operator is limited. The adjacent vehicle may have the required content, but temporarily does not have enough resources, and the requester has to wait. The proposed method expands the range of alternative providers, so the time the requester needs to wait in line will also be reduced accordingly. As can be seen, even in the case of small vehicle cache space, the proposed scheme can take advantage of multi-operator cooperation to find potential cross-operator content providers and reduce the communication pressure of network infrastructure.

[0123] 5.3 Comparison of service fees under different methods

[0124] Figure 8 The service fees of different methods are shown when the popularity of the requested content is increasing (quality level is 4). There are fewer alternative vehicles under a single operator, and they may not be able to hit all the content required by the requester, at which time the vehicle has to obtain the missing video layer from the base station at high cost. Therefore, the service fee generated by the proposed method is lower than that of the benchmark method 1. The cross-operator V2V video content delivery mode has a wider selection range, and the overall service fee is less. As shown in Figure 9 , under the same conditions, the proposed method can save more service fees for the requester. In order to better simulate the content request of vehicles, we initiated 100 Zipf-distributed requests for video content of different levels, and the average service fees under the two video content delivery modes are shown in Figure 10 . As can be seen, the proposed method expands the set of alternative vehicles, which can save more service fees for the requester.

[0125] It is assumed that the video content is randomly cached in each vehicle in the region. Figure 11The ratio of service cost to delay is compared under different methods when the popularity of the requested content is increasing. Under a single operator, the requester has a higher probability of obtaining content through V2I, which means a higher service cost needs to be paid. Under the proposed cross-operator V2V content sharing framework, although the content delivery speed of vehicles is slower than that of base stations, it can provide most of the content to the requester at a lower service cost.

[0126] 6Summary

[0127] This paper proposes a cross-operator V2V video content distribution method based on alliance chain. In view of the problem of cross-operator video content delivery, a hierarchical multi-chain alliance chain architecture combining cross-operator transaction main chain and operator sub-chain is designed, aiming to break the transaction barriers between different operators and realize content-centered transaction record management. At the same time, an optimal vehicle group selection algorithm based on comprehensive matching degree is designed under the cross-operator mode to select the vehicle set that best meets the conditions and can save the requester's cost to the greatest extent. Considering that the content transaction of cross-operator vehicles depends on the transaction upload and contract call of base stations, a cross-operator V2V contract call mechanism is proposed. By issuing rewards to base stations, the base stations are encouraged to upload transaction data quickly. Thus, the contract call delay is reduced, and the transaction interruption caused by the excessive response time of cross-operator video content transaction is avoided. Finally, the performance of the proposed method is verified by simulation experiments, and the results show the superiority and feasibility of the proposed method.

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Claims

1. A cross-carrier V2V video content sharing method based on consortium blockchain, characterized by: include: Step 1) Construct a cross-carrier V2V architecture based on a consortium blockchain; Step 2) Under the cross-carrier V2V architecture, the optimal vehicle group selection algorithm based on comprehensive matching degree is adopted. Under the constraints of vehicle reputation, V2V connection duration and achievable transmission rate, the content with the lowest service fee cost is selected to provide vehicles. In step 1), the cross-carrier V2V architecture includes: a content delivery layer, an information management layer, and a transaction consensus layer; Content delivery layer: Composed of vehicles and base stations with caching and communication capabilities, it is responsible for delivering video content across operators; the function of this layer is to complete the transaction upload while ensuring stable transmission of video content in a cross-operator V2V transaction environment. Information Management Layer: This layer is responsible for vehicle authentication and security checks to ensure that vehicles meet security and communication protocol requirements; this layer also records and stores information on video content releases and transaction execution results. Transaction Consensus Layer: This layer is responsible for consensus verification of cross-carrier V2V video content transactions to realize value exchange between vehicles of different carriers; this layer stores the smart contracts that execute content transactions and vehicle reputation information that needs to be frequently read and written for transaction verification; nodes participating in transaction consensus must reach a consensus on content delivery to ensure that all transactions are trustworthy; In step 2), the design process of the optimal vehicle group selection algorithm is as follows: 2.1) Analyze the associated conditions for the service fee generated by the vehicle requesting the content: According to the Scalable Video Coding (SVC) technique, video content n is encoded into M layers, and the set of video layer indices is represented as... Video quality is related to the number of video layers; This represents a collection of video content, where... It is an index of video content, c n This represents the content of the nth video; Use c n,m This represents the m-th video layer of video content n; The utility that a content request vehicle can obtain is related to the popularity and size of the resulting video: When the content requesting vehicle receives the video layer c from the content providing vehicle j. n,m At that time, the utility ω obtained j,n,m Calculated as: Where f n,m c n,m popularity, s j,n,m This indicates that the vehicle requested c was obtained from the vehicle j that provided it. n,m size, χ,δ, represents the average size of the video layer in the vehicle-to-everything (V2X) network. Both τ and τ are adjustable parameters; The set of neighboring vehicles of vehicle i The set of vehicle indices carrying video content n is represented as follows: Request vehicle i to pass through vehicle After obtaining video content n, the utility generated is calculated as follows: ω j,n,m This indicates that c is obtained through vehicle j. n,m The utility; The service fees a vehicle can earn are positively correlated with its credit score: Vehicle i from Get c n,m Service fee generated κ j,n,m Calculated as: Where t i,j,n,m This indicates that the base station is for vehicle j to upload video layer c. n,m The time point of the transaction, t i ' ,j,n,m For vehicles The time point at which the transaction request is initiated, r j p represents the reputation value of vehicle j. n,m It is the video layer c n,m The price λ are all adjustable parameters; If the nearby vehicle has no cache c n,m At this time, vehicle i only obtains c from the base station. n,m Vehicle i obtains c from base station b n,m The service fee generated is calculated as follows: in, ω is an adjustable parameter. x,n,m This indicates that c is obtained through the base station. n,m The utility; 2.2) Model and solve the vehicle selection problem under a multi-operator cooperation model: 2.2.1) Let the binary decision variable a i,j,n,m =1 represents the content request vehicle i selects the content to provide vehicle. Provide video layer c n,m ; For a vehicle i to request video content n, the content provider vehicle selection problem is modeled as follows: The essence is to solve under video quality constraints. To minimize service fees, among which, This indicates the optimal set of vehicles provided; Constraints: t i,j,n,m ≤t′ i,j,n,m +t0 (5c) a i,j,n,m If vehicle i cannot obtain the required content through V2V mode, then V2I mode is used to obtain the required content. Service fees reached their highest level. If the V2V mode is used, all video layers can be obtained. The objective function is transformed into The problem at this time Equivalent to from Find a set of vehicles that minimizes the service fee; Under constraint (5a), ensure c n,m The vehicles provided meet the minimum reputation requirements; α is used to adjust the reputation value, β is a weighting factor for content popularity, and r j Represents the reputation value of vehicle j; Under constraint (5b), the content-providing vehicle j maintains a connection for the duration d of the period. i,j Inside, c must be completed. n,m The delivery; where w j This represents the achievable transmission rate for vehicle j. Before video content transactions can take place, the content provider vehicle needs to upload a transaction request to the main chain via a base station to invoke the transaction contract; if the base station takes t minutes to upload the transaction... i,j,n,m -t′ i,j,n,m Exceeding the specified time limit t0 will result in the termination of subsequent vehicle content transactions; if the vehicle Selected as C n,m If the vehicle is provided, then t i,j,n,m Constraint (5c) must be satisfied; 2.2.2) A vehicle selection algorithm based on comprehensive matching degree is used to solve the problem. The steps include: (1) Global variables Min and These are used to record the total service fee required to obtain content n and the optimal set of vehicles providing the content, respectively. (2) Based on reputation score, sustained connection time, and transaction upload latency, c n,m The optional content provides a set of vehicles for updating; if the quality requirements of the content request vehicle i have been met, the current total service fee is compared with Min; if the current total service fee is smaller, Min is updated and the current decision is recorded. (3) If the video quality requirements of the content requesting vehicle i are not yet met, determine the number of vehicles providing the optional content in the current layer. If c n,m If no vehicle is provided, the base station will provide it. n,m ; (4) If c n,m If there are other vehicles available as content providers, then iterate through all possible decision-making options; try using the available vehicles as content providers and update the temporary decision-making options; in the case of c n,m After selecting the content provider vehicle, the next level of content provider vehicles is selected; when backtracking through other decision options, some variables need to be restored to their previous state. (5) Finally, after searching all possible strategies, the solution that minimizes service fees will be updated to...

2. The cross-carrier V2V video content sharing method based on consortium blockchain according to claim 1, characterized in that: In step 2), an incentive mechanism is also used to encourage base stations to quickly upload transaction data.

3. The cross-carrier V2V video content sharing method based on consortium blockchain according to claim 1 or 2, characterized in that: The design of the cross-carrier V2V architecture includes: I. Layered Multi-Chain Structure Design: Cross-Carrier V2V Architecture has two types of chains: 1) Carrier Subchain: In the cross-carrier V2V architecture, video content delivery will generate a large number of transaction records; each carrier maintains a subchain to record its own published video content and related transactions, realizing content-centric transaction data distribution and storage; carriers can quickly query content flow information through the transaction records in the subchain; 2) Cross-operator transaction main chain: The main chain is jointly built by an alliance of multiple operators, responsible for deploying smart contracts and recording reputation values. Operators set up and deploy smart contract video content according to the alliance rules. After the contract is authorized and published to the main chain by the operator, it is broadcast to the vehicle-to-everything (V2V) environment via base stations. V2V video content transactions require consensus to be reached on the main chain to ensure global consistency of transaction processing results. After a vehicle-initiated content transaction is verified, the reputation value of the transacting parties is updated to the main chain. Simultaneously, the content transaction results verified by the main chain will be stored in the sub-chain corresponding to the transaction content through cross-chain interaction. II. Trusted Cross-Chain Data Interaction Design: Both the main chain and sub-chains are equipped with proof modules to verify the authenticity of cross-chain interaction information. A verification mechanism based on signatures and Merkle hash trees is used to verify the identity of verification nodes and the source of data. The process of exchanging transaction query information from the main chain to the child chain includes the following steps: Step 1: When a node needs to query transaction information in the operator's subchain, it sends a transaction record query by calling the smart contract in the main chain. The query identifier is q. Step 2: The main chain's proof module assigns an authorization identifier ε to the query, then packages the relevant information, signs it as Sign(q,ε), and sends it to the operator's sub-chain; Step 3: After receiving the information Sign(q,ε), the proof module on the operator's subchain verifies the authenticity of the signature information Sign(q,ε); Step 4: If authentication is successful, the query request q will search the data records in the subchain; Step 5: After obtaining the query result Info(q), in order to prove the authenticity of the query result, the operator's subchain needs to provide additional proof information, represented as P(Info(q)), which represents the Merkle verification path of Info(q) in the subchain; and send the signed query result Sign(Info(q),P(Info(q))) to the main chain; Step 6: After Sign(Info(q), P(Info(q))) passes the verification by the main chain proof module, the smart contract will obtain the transaction query result Info(q); The process of a subchain interacting with the main chain to query transaction information is the same as the process of the main chain interacting with the subchain to query transaction information; however, the roles of the two parties are reversed in the process.

4. The cross-carrier V2V video content sharing method based on consortium blockchain according to claim 2, characterized in that... In step 2), the incentive mechanism is a cross-carrier V2V contract call mechanism; Before the transaction contract is executed, the vehicle providing the content needs to upload transaction information via a base station. In this process, a cross-carrier V2V contract call mechanism is used to incentivize the base station to speed up the upload of transaction requests by issuing rewards, thereby avoiding transaction interruption. Assume base station b is a vehicle Uploaded video layer c n,m Transaction information: Base station b's contribution to this video request is calculated as follows: When base station b uploads transaction requests for other video layers related to content n, its contribution continues to accumulate; Once the transaction is completed, the reward amount received by base station b, which assisted in uploading the transaction data, from the operator is calculated as follows: Where g is an adjustable parameter; the shorter the interval between base station uploading transactions, the higher the reward; if the base station cannot upload the transaction to the main chain within the valid time limit t0, it will not receive any reward. Suppose that vehicle j of operator A caches video layer c from operator B. n,m When the vehicle Provide content to vehicle i n,m At that time, the submitted transaction undergoes the following processing steps: Step ①: Vehicle j, acting as the content provider vehicle, sends c to vehicle i. n,m Sign the contract address information The transaction signature is then uploaded to Operator A's base station; This indicates two signatures; the first signature uses i's private key K. S i The second signature uses j's private key K. S i ; Step 2: Operator A's base station uploads the transaction requests initiated by both parties to the main chain; Step 3: The proof module in the main chain obtains the signature information, calls and executes the corresponding smart contract. Step 4: The main chain, as the blockchain that maintains the global reputation value, updates the relevant vehicle reputation value; Step 5: After the main chain completes transaction verification, it transmits the transaction results to the sub-chain of operator B, thereby realizing content-centric transaction record storage; Step 6: Operator B's subchain verifies the credibility of the result sent by the main chain through the proof module; Step 7: After transaction verification is completed, the operator will process the relevant data. n,m The transaction records are updated and stored; The transaction contract invocation process is as follows: After vehicle i initiates a transaction with content provider vehicle j, content provider vehicle j sends the signed transaction information to the base station, and the base station uploads the transaction to the main chain; after the relevant contract in the main chain is successfully invoked, pre-deductions are executed from the accounts of both parties to the transaction; after the transaction consensus verification is completed, the smart contract will distribute rewards to participants based on the collected transaction scores and transaction proof certificates; the smart contract SmartCon... cn,m The execution results are submitted to the subchain, thereby achieving content-centric transaction storage.

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