CN107371211B - An opportunistic network routing method with low overhead and high transaction success rate - Google Patents

Abstract

The invention proposes an opportunistic network routing method with low overhead and high transaction success rate. It consists of node operations in three stages: node encounter perception, game and data packet delivery, and transaction settlement, which are logically sequenced, including "adaptive reduced packet summaries", "adaptive merging of SV-DP messages and purchase requests". There are three new mechanisms: "message" and "comprehensive consideration of buying and selling income when gaming", all of which work in the gaming and data packet delivery stages. The new routing method reduces the transmission of control information in the routing process by eliminating redundant packet summaries in SV-DP messages, adaptively combining SV-DP messages and packet buy messages, and comprehensively calculating the payoffs of node buying and selling operations in a game. , improve the success rate of nodes reaching transactions through games, and increase the chance of data packets being forwarded in the network, thereby improving the success rate of data transmission and network throughput, reducing control overhead and data end-to-end delay.

Description

An opportunistic network routing method with low overhead and high transaction success rate

technical field

The invention belongs to the technical field of Opportunistic Networks, and in particular relates to an occasion where an economic game theory method is adopted in an opportunistic network containing selfish nodes to motivate selfish nodes to participate in network data forwarding.

Background technique

Opportunistic network is a wireless ad hoc network that can tolerate delay and split. Its typical feature is that it does not require a complete link between the source node and the destination node, and uses the encounter opportunities brought by the mobility of nodes to achieve communication. Because it is difficult to establish a fully connected network in many application fields, the traditional wireless ad hoc network protocol cannot be used normally, and this feature of the opportunistic network enables it to better meet these needs. In recent years, opportunistic networks have become one of the important research directions of wireless ad hoc networks, and have been widely used. For example, the SNC (SamiNomadic Connectivity) network connectivity project launched in Finland has effectively solved the problem of inconvenient Internet access in remote areas; In terms of wildlife monitoring, ZebraNet, a wildlife tracking project proposed by Princeton University based on Opportunity Network, uses zebras’ living habits to collect data by placing sensors on zebras. Similar applications include SWIM (SWIM) ( Shared Wireless Infostation Mode) project, etc.

An opportunistic network is a wireless self-organizing network in which each node in the network has limited resources, such as battery, memory, CPU, and network bandwidth. In order to protect its own resources, the nodes in the network will refuse to consume their own resources to forward data for other nodes. This selfish behavior will hinder the forwarding of data packets in the network. A large number of literatures have proved through theory and experiment that the existence of selfish nodes will seriously affect the performance of opportunistic networks.

For the selfish behavior of nodes, researchers have proposed a variety of solutions. One of the feasible solutions is to introduce the game strategy in economics into the chance network, and simulate the nodes in the network as players in the game. According to the game strategy, nodes often choose strategies that maximize their own interests during the game process. By designing punishment and incentive mechanisms, the short-term benefits of nodes due to selfishness are lower than the long-term benefits of cooperative forwarding, forcing selfish nodes to adopt cooperative strategies. , so that the optimal revenue strategy of the node is consistent with the optimal performance of the network, so as to avoid the waste of precious communication resources due to the selfish behavior of the node.

The mechanism of Marti et al. to deal with the problem of selfish nodes in the network earlier is the watchdog&pathrater (see Reference [1]: Sergio Marti, T J Giuli, Kiven Lai, Mary Baker. Mitigating routing misbehavior in mobile ad hoc networks [C ]. The 6th Annual International Conference on Mobile Computing And Networking (MobiCom 2000), 2000: 255-265). The mechanism uses monitoring to detect the behavior of other nodes in the network. After the current node sends the data packet to the next-hop node, it monitors whether the next-hop node forwards the data packet. If the next hop node forwards the data packet unchanged within the specified time, it means that the next hop has cooperated; otherwise, it means that the next hop has uncooperative behavior. The watchdog is used to detect nodes that behave selfishly, and the pathrater is responsible for avoiding these nodes when making next-hop node selection. The watchdog has a relatively obvious effect in the network where the node position is fixed, but in the opportunistic network, due to the random movement of the node and the uncertainty of the link status in the network, the node behavior is often difficult to detect by monitoring, and the current node is often unable to detect. Correctly determine whether the next hop node forwards the data packet.

In the follow-up research, on the basis of the existing technology, Tang et al. proposed a selfish node detection mechanism based on reputation value maintenance - 2-ACK (see reference [2]: Tang Xiao, Yuan Yijia, Dong Yongqiang, Wu Guoxin .An Opportunistic Network Selfish Node Detection Mechanism Based on Reputation Value Maintenance [J]. Journal of Communications, 2012, 33(z2): 217-221). The mechanism uses two-hop ACK response data packets to determine whether the node has selfish behavior, uses the monitoring information to calculate the reputation value of the node, and uses the comprehensive reputation value as the basis for judging whether the node is selfish. Each node in the network maintains and calculates a list of comprehensive reputation values for other nodes, and sets a reputation value threshold. Nodes with a reputation value higher than this threshold are identified as non-selfish nodes, while nodes with a reputation value lower than the secondary threshold are identified as non-selfish nodes. It is identified as a selfish node, and the comprehensive reputation value is affected by the direct reputation value and the indirect reputation value. After the next-hop node of the current node encounters the previous-hop node, it provides the previous-hop node with ACK information that proves that the current node has forwarded the data packet. According to the ACK information, the previous hop node increases the reputation value of the current node. This method reduces the listening behavior of the next-hop node, but the encounter probability of the current node's next-hop node and the previous-hop node will seriously affect the previous-hop node's judgment of the selfishness of the current node.

Shuzhen Xu et al. proposed a method to introduce game theory into an opportunistic network with selfish nodes to stimulate selfish nodes to actively participate in network collaboration---CRGTD (Credit-based Repeated Game model applied in Transfer Decision, see Reference [3]: Shuzhen Xu, Mingchu Li, Yuanfang Chen, Lei Shu, Xin Gu. A cooperation scheme based on reputation for opportunistic networks [C]. 2013 International Conference on Computing, Management, and Telecommunications (ComManTel 2013), 2013: 289-294). The approach is a credit and repeated game-based solution that typically operates in conjunction with an infection routing mechanism, exchanging control information and data packets as nodes meet. The CRGTD scheme introduces a credit cooperation mechanism, improves the single-stage game into a repeated game process within the network running time, and punishes nodes with selfish behavior by setting punishment measures and punishment cycles, and refuses to forward from or to such node's packets. In this way, rational selfish nodes have to reduce selfish behavior in order to obtain greater benefits, which is beneficial to the improvement of the success rate of data packet transmission in the network. The CRGTD scheme sets the rules for nodes to select trading strategies. If a node selects a trading strategy according to the rules, it is considered to be a non-selfish node. Otherwise, it is judged to have selfish behavior and will be punished accordingly. The punished node can pass the penalty cycle. 's cooperative behavior releases itself from the punished state. The CRGTD mechanism can effectively reduce the selfish behavior of nodes, but the failure of the game due to a single selfish behavior is not enough to judge a node as a selfish node, so it converges slowly in the judgment of a selfish node.

In order to reduce the number of packet copies in the network, Fan Wu et al. proposed a game method based on probabilistic routing - GSCP (A Game-Theoretic Approach to Stimulate Cooperation for Probabilistic Routing in Opportunistic Networks, see reference [4]: Fan Wu, TingtingChen,Sheng Zhong,Chunming Qiao,Guihai Chen.A game-theoretic approach tostimulate cooperation for probabilistic routing in opportunistic networks[J].IEEE Transactions on Wireless Communications,2013,12(4):1573-1583). In GSCP, when two nodes carrying data packets meet, they will exchange each other's SV (Summary Vector, whose main content is a summary list of data packets carried by the current node. The data packet summary usually includes the source node of the data packet, Destination node, serial number, length and other information) and the delivery probability (Delivery Predictability, DP) list (a table composed of the predicted probability of encountering the current node and other nodes, also known as the DP list); After the SV and DP are listed (installed in an SV-DP message), the current node can determine the data package that it needs to buy from the other party through calculation, and can calculate the price reported to the other party node. The price x is calculated by the following formula:

Among them, T(m) and P(m) are the transmission and reception overhead of data packet m respectively (related to the length of the data packet, which can be set as a uniform, small constant coefficient × data packet length for the entire network), V _i (m) is the value of the data packet m for the game participating node i, which is defined by the following formula:

_Vi (m)=ω·P _i,d (2)

where ω is the fee paid by the source node of the data packet m to successfully forward m to the destination node (the entire network node uses the same ω value), and P _i,d is the encounter probability between node i and the destination node d of the data packet m. The node that wants to buy the data package m (that is, the buyer node) uses the following formula to calculate the profit u _B after it reaches the transaction through the game:

u _B =V _B (m)-P(m)-xC _B (γ) (3)

where x is the offer price, and C _B (γ) is the cost of the buyer node in each round of bargaining game. The buyer node judges that if u _B is less than 0, it does not purchase the data package m from the opposite node; if u _B is > 0, it needs to purchase the data package m from the opposite node, and then sends the purchase request to the opposite node (ie, the seller node). information. If a node receives the message m from the encounter node, it is the seller node, and it uses the following formula to calculate its own profit u _S after reaching the transaction through the game:

u _S =xV _S (m)-T(m)-C _S (γ) (4)

where x is the offer price and C _S (γ) is the cost of the seller in each round of bargaining game. The seller node judges that if u _S is < 0, it will not sell the data packet m to the opposite node; if u _S is > 0, it will sell the data packet m to the opposite node, and then send the data packet to the opposite node (that is, the buyer node). m. For each transaction of buying and selling data packets between nodes, the transaction fee settlement agency in the network - the transaction settlement center CCC will charge the seller node a transaction fee X(m,x), the size of which is related to the transaction price of the seller node , the calculation formula is as follows:

Among them, γ≤(V _B (m)-V _S (m)-T(m)-P(m))/2-σ is a small basic transaction cost, and the transaction cost factor σ is a preset Parameter, 0≤σ≤(V _B (m)-V _S (m)-T(m)-P(m))/2; transaction cost parameter k=2-2γ/(V _B (m)-V _S (m)-T(m)-P(m)) is the transaction cost coefficient when the seller's node transaction price is higher than the optimal price.

The GSCP method regards the exchange of control messages and data packets between nodes in probabilistic routing as a bargaining game, and the typical message interaction and data packet transmission process is shown in Figure 1 of the specification; Route transmission with increasing probability, which helps to improve the success rate of data packet transmission; but the node-to-node game it defines is based on the condition that the difference between the forwarding probability of buyers and sellers is higher than a certain threshold, which has It may make the game strategy of cooperative forwarding unable to be achieved when the difference between the forwarding probability between buyers and sellers is small, which may waste the opportunity of data packet forwarding.

In addition, in the existing related routing methods represented by GSCP, the one-way transfer of data packets affects the increase of forwarding probability, the dependence on virtual currency for transactions weakens the purchasing power of nodes, and there are redundant interactions in the data packet transaction process. designed an efficient game method - HLPR-MG (High-throughput and low-overhead probability routing based on multi-player bargaining game) (see references: Ren Zhi, Suo Jianwei, Liu Wenpeng, Lei Hongjiang, Chen Qianbin. High-throughput and low-overhead probabilistic routing algorithm for opportunistic networks based on multi-party bargaining game [J]. Journal of Communications, 2017, 36(6): 41-48). This mechanism expands the two-way game of nodes to a multi-party game to speed up the improvement of the probability of data packet forwarding. At the same time, it introduces a "barter" method to enhance the purchasing power of nodes, and improves the existing interaction mechanism to reduce the number of games, so as to improve the network throughput. and reduce the control overhead.

To sum up, people have conducted in-depth research on opportunistic network routing methods with selfish nodes, especially the game theory method introduced into economics, and some progress has been made in stimulating selfish nodes to actively participate in packet forwarding, but Through in-depth research, we found that the existing opportunistic network routing methods based on game theory have the following problems:

1. In the existing game-based probabilistic routing methods (such as GSCP), the revenue of a single game will affect the possibility of both parties to the game reaching a transaction. In a single game, only when the revenue of both parties is not less than 0, both parties A transaction will be reached and a cooperative forwarding strategy will be adopted; such a processing method does not consider that the seller may have made a profit when the data packet is bought, which reduces the ratio of the two sides of the game to reach a transaction (ie, the transaction is successful) and adopt a cooperative forwarding strategy.

2. Before the node forwards the data packet, it needs to exchange the SV-DP message, which contains the summary vector SV and the Delivery Predictability (DP) list (a table composed of the predicted encounter probability between the current node and other nodes, also may be called a DP list). When two nodes meet, after the DP list interaction is completed, the node that receives the DP list can know the probability of encountering the two nodes to other nodes; at this time, if the node meets the probability of encountering the destination node of some data packets in the SV higher than the encountering node, the encountering node will not be able to purchase these data packets (because the income after the purchase will be less than 0), so there is no need to send the summary of these data packets to the encountering node. However, the existing mechanism SV-DP message In the interactive process, the summary of such data packets will still be added to the SV and sent to the encountering nodes, thus resulting in redundancy of the data packet summary and unnecessary control overhead.

3. There are redundant control messages in the process of data packet transactions. In the existing related method, when the data package is traded between two nodes, the purchase message requesting to purchase the data package needs to be sent by the buyer node to the seller node separately. Through research, it is found that the source and destination nodes of the purchase message are the same as the source and destination nodes of the SV information, so the SV-DP messages can be combined and sent together, but sending the purchase message alone will make the control message redundant.

4. Each data packet in the opportunistic network is set with a positive integer field of "lifetime", which indicates the number of times the data packet can be forwarded; when the life time = 0, the data packet can no longer be forwarded and will be discarded ; However, in the process of data packet interaction, the node cannot know the value of the lifetime field of the data packet through the control message (including the hello message and the SV message), so that the node may purchase the data packet with the lifetime field value of 1; here In this case, the lifetime value of the data packet purchased by the node will become 0, so the node has to discard the data packet, resulting in unnecessary forwarding overhead and operations.

The existence of the above problems makes the transaction success rate of both parties in the opportunistic network with selfish nodes low, resulting in fewer opportunities for data packet transmission, the success rate of data packet transmission will decrease and the transmission delay will increase. The extra control overhead increases the load and energy consumption of the network. In order to solve the above problems and improve the transmission performance of opportunistic networks with selfish nodes, it is necessary to propose new methods to solve them. The present invention will propose practical solutions to these problems.

SUMMARY OF THE INVENTION

In order to solve the problem that the above-mentioned SV-DP message contains redundant data packet summaries, in some cases, the buyer node sends a special purchase message to bring redundant overhead, after purchasing a data packet with a lifetime of 1, it cannot be forwarded, and the purchase price is calculated separately. In order to solve the four problems that the transaction is not easy to succeed due to the income, the present invention proposes an opportunistic network routing method with low overhead and high transaction success rate; There are three new mechanisms: "message" and "comprehensive consideration of buying and selling income during gaming". By eliminating redundant summaries in SV messages, piggybacking buying information in SV messages, and comprehensively calculating the returns of node buying and selling operations in the game, it reduces control over the routing process. The transmission of information improves the success rate of nodes reaching transactions through games, and increases the chance of data packets being forwarded in the network, thereby improving the success rate of data transmission and network throughput, and reducing control overhead and data end-to-end delay.

(1) The basic idea and main operation of the new mechanism proposed by the present invention

The basic ideas and main operations of the three new mechanisms of "self-adaptive and simplified data packet digest", "self-adaptive merging of SV-DP messages and purchase messages" and "comprehensive consideration of buying and selling income during gaming" proposed by the present invention are described in detail below.

1. Adaptive Reduced Packet Summary

The new mechanism of "Adaptive Reduced Packet Digest" solves the following two problems:

(1) The SV-DP message used by the existing related opportunistic network routing methods includes the SV (which contains the summaries of all data packets) and the DP list; The node can know the probability of encounter between the nodes of both parties to other nodes. At this time, if the probability of encounter between the node and the destination address of some data packets in the SV is higher than that of the encounter node, the encounter node cannot request to purchase these data packets (because after purchase The benefit will be less than 0), however, the existing related routing methods still add the summary of this type of data packet to the SV, which will bring unnecessary control overhead.

(2) Each data packet in the network is set with a lifetime field, which records the number of hops that the data packet can be transmitted. The hop value is reduced by 1 each time it is forwarded. When the hop value is reduced to 0, the data packet can no longer be forwarded. . In the process of SV-DP message exchange, since the node cannot know the current hop value of the data packet, the node may request the data packet whose hop value has been reduced to 1. In this case, if the current node is not a data packet The destination node will bring unnecessary forwarding overhead; because the data packet can no longer be forwarded, the node can only delete the data packet after receiving it.

The basic idea of the new mechanism of "Adaptive Reduced Packet Digest" is as follows:

The node is sending the SV-DP or DP-SV-BUY message (a new control message proposed by the present invention, including the DP list, SV, and the summary of the data package requested to purchase, which is essentially the original SV-DP message. The message that is merged with the purchase message, the message header is provided with a field (the default recommended length is 16 bits) to store the number of data packet summaries in the DP-SV-BUY message. For the specific structure, please refer to Figure 2 in the description. Before entering the summary of the data packet, first determine whether the value of the lifetime field of the data packet is > 1 and whether the probability of encountering itself with the destination node of the data packet < the probability of encountering the encounter node and the destination node of the data packet; only when the value of the "lifetime field" Whether > 1" and "whether the encounter probability between the current node and the destination node of the packet is < the encounter probability between the encounter node and the destination node of the packet", the current node will load the summary of the packet into SV-DP or DP-SV -BUY message, thus avoiding loading useless packet digests and eliminating the redundant control information brought by it.

The basic process of the new mechanism of "Adaptive Reduced Packet Digest" is shown in Figure 3 of the specification. The main operations are as follows:

(1) Each node independently judges whether it has received the hello message broadcast by other nodes; if so, execute the next step; if not, execute step (4).

(2) The current node generates an SV-DP message.

(3) The current node judges whether there is a data packet summary that needs to be loaded into the SV-DP message; if not, the operation of this mechanism is ended; if so, judge whether the lifetime field value of the data packet is > 1; if so, Then load the digest of the packet; if not, do not load, and then loop through this step.

(4) The current node judges whether it has received the SV-DP message sent by other nodes; if so, execute the next step (the node that sends the SV-DP message is the encounter node at this time); if not, turn to the ( 1) step.

(5) The current node generates a DP-SV-BUY message (distinguished from other data packets by the value of the "type" field of the data packet).

(6) The current node judges whether there is a data packet digest that needs to be loaded into the DP-SV-BUY message; if not, then end the operation of this mechanism; if there is, then judge whether the lifetime field value of the data packet is >1; If yes, go to the next step; if not, execute this step in a loop.

(7) current node judges whether the probability of encounter of oneself and the destination node of the data packet < the probability of encountering the node and the destination node of the data packet; if yes, then load the summary of this data packet, then go to step (6); if not, If it is not loaded, go to step (6).

2. Adaptively merge SV-DP message and buy message

In the existing opportunistic network-related routing methods, when the encountering nodes exchange information, the mechanism used is to first exchange the SV and DP lists of the two parties; after the nodes receive the other party's SV and DP lists, they will Make a purchase request and send a purchase message. Since the source and destination nodes of the purchase message are the same as the SV-DP message, they can be combined and transmitted without exceeding the maximum length limit of the packet. In this case, when a node sends the SV-DP message and the purchase message respectively, a control message redundancy.

In order to solve this problem, the present invention proposes a new mechanism of "adaptively combining SV-DP message and purchase message". Its basic idea is: if the current node receives the other party's SV-DP message before sending its own SV-DP message, DP message, then generate a DP-SV-BUY message and load the DP list and data packet summary into the message; then, judge whether the DP-SV-BUY message can hold the next data packet purchase information (including the data packet source node) , serial number and quotation), that is, judge whether the length of the header of the DP-SV-BUY message + DP list + SV + a data packet purchase information is less than the maximum length limit of the control message; The destination node of the package, the probability of encountering the destination node in the other party's DP list, and the probability of encountering the destination node in its own DP list, determine whether to purchase the other party's data package; if you want to purchase, calculate the data to be purchased. The optimal price of the package under the game equilibrium; next, the data package purchase information is loaded into the DP-SV-BUY message (as much as can be loaded without exceeding the maximum length limit of the control message), so as to The overall reduction in the number of packet-purchase messages.

The basic process of the new mechanism of "adaptively combining SV-DP message and purchase message" is shown in Figure 4 of the description, and the main operations are as follows:

(1) A node judges whether it has received the SV-DP message sent by another node; if so, execute the next step; if not, end the operation of this mechanism.

(2) The current node generates a DP-SV-BUY message and loads the DP list and the packet digest in the SV.

(3) The current node judges whether the DP-SV-BUY message can hold the purchase information of the next data packet; if so, execute the next step; if not, end the operation of this mechanism.

(4) The current node judges whether to purchase the data package of the opposite node (the node that sent the SV-DP message); if so, execute the next step; if not, end the operation of this mechanism.

(5) The current node loads the information of a purchase data packet (including the source node address, sequence number, and quotation of the data packet) into the DP-SV-BUY message (placed behind the SV and loaded one by one), and then goes to (3) step.

3. Comprehensive consideration of trading income when gaming

According to the existing opportunistic network routing method based on bargaining game, when buyers and sellers play a game, only when the income of both sides of the game (the income is related to the probability of encountering the node and the destination node, the loss of sending and receiving data packets, the game loss, etc.) When it is not less than 0, the two parties will reach a transaction (that is, the transaction is successful), and thus adopt a cooperative forwarding strategy. The seller will calculate its own profit after receiving the buyer's offer for the data package. If the calculated profit is less than 0, it will refuse to accept the offer, so the transaction cannot be completed, the game will fail, and the data packet will not be forwarded. Losing the game has potentially adverse effects on the transmission of packets. In order to solve this problem, we propose a new mechanism of "comprehensive consideration of buying and selling income when gaming". The basic idea of this new mechanism is as follows:

When a node purchases a data package through the game, it will save the income at the time of purchase (referred to as "revenue at the time of purchase"; a field of "revenue at the time of purchase" is added to the entry corresponding to the data package in SV for storage "Benefit when buying"; do not send "revenue when buying" when sending a packet summary to other nodes); when other nodes want to buy the data packet and send a quotation, the current node calculates the income from selling the packet according to the quotation (referred to as is "sell-time income"), and then judge whether the buy-time income + sell-time income > 0; if so, accept the buyer's node offer and agree to the transaction; otherwise, reject the transaction (the existing relevant method is whether the sell-time income > 0 agree to the transaction). In this way, since the income of buying and selling data packets is comprehensively calculated in the game process, the requirements for the income when selling are reduced under the condition of ensuring whether the total income of the current node is > 0, and the opportunity for the buyer and seller to reach a transaction is increased. It can improve the transaction success rate and increase the chance of data packets being forwarded, thereby promoting the increase of network throughput and the reduction of the average end-to-end delay of data packets.

The basic process of the new mechanism of "comprehensive consideration of buying and selling income when gaming" is shown in Figure 5 of the description. The main operations are as follows:

(1) After each node purchases the data package of another node, it stores the purchase income in the "purchase income" field of the corresponding entry of the data package in the SV.

(2) The node judges whether there are other nodes seeking to purchase data packets; if so, execute the next step; if not, end the operation of this mechanism.

(3) The node takes out the offer value in the received purchase information of the data packet, and calculates the "sell-time income" of the data packet.

(4) The node calculates and judges whether the income at the time of buying + the income at the time of selling is > 0; if so, accept the offer from the buyer node, agree to the transaction, and send a data packet to the buyer node; if not, reject the transaction and reply to the buyer node with a "" Transaction rejected" message, then ends the operation of the mechanism.

(2) Main operations of the opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention

The opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention is composed of node operations in three stages logically sequenced: node encounter perception, game and data packet transmission, and transaction settlement. There are three new mechanisms, namely “Summary”, “Adaptive Merging of SV-DP Messages and Purchasing Messages”, and “Comprehensive Consideration of Buying and Selling Profits in Gaming”, all of which work in the stages of gaming and data packet delivery, as shown in Figure 6 of the specification.

The low overhead and high transaction success rate opportunistic network routing method proposed by the present invention has the following presets:

(1) When the network starts running, each node has the same virtual currency value.

(2) When each node obtains data packets from other nodes, it needs to use a certain amount of virtual currency to purchase. During the purchase, the two nodes use the form of game to negotiate the price; the virtual currency value owned by the node after buying the data packet will be determined according to the price. The transaction price is reduced by paying the virtual currency to the other party. If the node's remaining virtual currency value is not enough to buy a data package, it cannot get the data package.

(3) In the process of each transaction data packet, there will be transmission and reception overhead, and the buyer and seller nodes will generate game costs, which need to be deducted from the virtual currency value of the buyer or seller node.

(4) There is a special node with a fixed (or mobile) location in the network - the Credit Clearance Center (CCC) as a transaction fee settlement agency. For each transaction of buying and selling data packets between nodes, CCC will charge A transaction fee for the seller node.

The main operations of the new routing method proposed by the present invention are introduced in stages below.

1. Node encounter perception

The basic operation process of the node encounter perception stage is shown in Figure 7 of the specification, and the main operation steps are as follows:

P1-S1: Nodes in the network periodically broadcast hello messages to announce their existence.

P1-S2: If a node receives a hello message broadcast by other nodes, it first extracts the source node address of the message; then, in the DP list, it queries whether the encounter probability value with the node is 0 (the encounter probability value is 0). Indicates that it has never met); if it is 0, modify the encounter probability value to the initial value of the encounter probability (the default recommendation is set to 0.5); if it is not 0, modify the encounter probability value with the node according to the following formula:

P _(s,b) =P _(s,b)old +(1-P _(s,b)old )×P _init (6)

In the formula, P _(s,b) and P _(s,b)old represent the latest and previous encounter probability values of nodes s and d, respectively; P _init represents the initial value of the encounter probability. Finally, the current node generates an SV-DP message, loads the SV and DP list and other information into it, and then sends it to the opposite node.

P1-S3: If a node receives an SV-DP message from another node, it first extracts the source node address of the message; next, it queries the DP list to see if the encounter probability value with the node is 0; if it is 0 , then modify the encounter probability value to the initial value of the encounter probability (the default recommendation is set to 0.5); if it is not 0, modify the encounter probability value with the node according to formula (6).

2. Gaming and packet delivery

The basic operation process of the game and data packet transmission stage is shown in Figure 8 of the specification, and the main operation steps are as follows:

P2-S1: Each node independently judges whether it has received SV-DP messages from other nodes; if so, it modifies the corresponding encounter probability value, and then executes the next step; if not, executes steps P2-S8: .

P2-S2: The current node adopts the new mechanism of "adaptively combining SV-DP message and purchase message" proposed by the present invention to generate a DP-SV-BUY message; then, the DP list is loaded into the DP-SV-BUY message.

P2-S3: The current node loads the digests of the data packets into the DP-SV-BUY message one by one, and uses the new mechanism of "adaptive and simplified data packet digest" proposed by the present invention in the process of loading, and loads the digest of a data packet into the DP -Before the SV-BUY message, it judges whether the value of the lifetime field of the data packet is > 1; if so, execute the next step; Steps P2-S5:.

P2-S4: The current node judges whether the encounter probability between itself and the destination node of the data packet < the encounter probability between the encounter node and the destination node of the data packet; if so, load the summary of the data packet into the DP-SV-BUY message, and then go to the step P2-S3:; if not, go to step P2-S3: directly.

P2-S5: The current node judges whether to request a purchase message from the opposite node; if yes, execute the next step; if not, send the DP-SV-BUY message to the opposite node, and then go to step P2-S8:.

P2-S6: The current node judges whether the DP-SV-BUY message can be loaded with a data packet purchase information (including the source address, serial number, and quotation of the data packet (the quotation is calculated according to formula (1)); The data packet purchase information is loaded into the DP-SV-BUY message (it is recommended to be placed after the SV by default), and then go to steps P2-S5:; if not, send the DP-SV-BUY message to the opposite node (that is, send the node for SV-DP messages).

P2-S7: The current node loads all the data packet purchase information that cannot be loaded by the DP-SV-BUY message into a purchase message, and then sends the message to the opposite node.

P2-S8: The current node judges whether it has received the DP-SV-BUY message sent by other nodes; if yes, execute the next step; if not, go to step P2-S10:.

P2-S9: The current node retrieves and stores the DP list, SV and purchase information from the DP-SV-BUY message (the length of the DP list is proportional to the total number of nodes in the network; the number of packet summaries contained in the SV is in the DP-SV-BUY There are records in the corresponding fields of the message header, and the length of each data packet summary and each purchase information is a fixed value); then, the quoted value is extracted from the purchase information and the sales revenue of the data packet is calculated based on it (the time of sale). The income is calculated according to formula (4)); then, using the new mechanism of "comprehensive consideration of trading income when gaming" proposed by the present invention, it is judged whether the buying income + selling income of the data package is > 0; if so, the transaction is agreed, and the The data packet is sent to the other party; if not, the transaction is rejected and no sending operation is performed.

P2-S10: The current node judges whether it has received a purchase message from other nodes; if yes, execute the next step; if not, go to steps P2-S12:.

P2-S11: The current node extracts the quoted value from the purchase information contained in the purchase request message and calculates the sale-time income of the data package based on it; Whether the income at the time of buying + the income at the time of selling is > 0; if so, agree to the transaction and send the data packet to the other party; if not, reject the transaction and do not do the sending operation.

P2-S12: The current node judges whether it has received data packets from other nodes; if so, store the data packets, and create a data packet summary corresponding to the data packet in the SV (including the source node of the data packet, the destination node, serial number, income at the time of purchase, etc.); then, generate a payment message (including the seller's node address, data package serial number, data package transaction price, etc.) and send the payment message to the data package's seller node; Next, Subtract the amount spent for purchasing the data package (that is, the transaction price of the data package) from your own virtual currency value; Enter the "revenue when buying" field of the data packet summary in the SV; if no data packets from other nodes are received, go to the next step.

P2-S13: The current node judges whether it has received a payment message from other nodes that corresponds to a data package sold by itself; if so, it generates a "data package sales record" message to record the transmission of the data package and receiving overhead, the value of the data packet to the buyer and seller nodes, and then store the “data packet sale record” in the pre-established “data packet sale record table”; go to step P2-S1:; if no other For the payment message sent by the node, go directly to step P2-S1:.

3. Transaction settlement stage

The core operation of the transaction settlement stage is that the transaction settlement center node CCC deducts the account of the seller node for each completed transaction. The basic operation processes of CCC and ordinary nodes (nodes other than CCC) are shown in Figure 9 and As shown in Figure 10, the main operation steps are as follows:

P3-S1: CCC periodically broadcasts a hello message, and the message contains its address.

P3-S2: If a node receives a hello message broadcast by CCC, it will determine whether it has a "packet sale record" that has not been reported to CCC; " into a newly generated "packet sell message", which is then sent to CCC; if not, no further action is performed.

P3-S3: If CCC receives a "packet selling message" from a node, it will take out all "packet selling records" from the message, and then use formula (5) to calculate the deducted amount according to these records. The cost is loaded into a newly generated "cost deduction message", and then the message is sent to the opposite node; and the deducted cost is added to the opposite node in the pre-established "node cost deduction table". In the corresponding "Total Expenses Deducted" table entry value.

P3-S4: If a node receives a "cost deduction message" sent by CCC, it will take out the cost value to be deducted carried in the message, and deduct the cost value from its remaining virtual currency value; if it does not receive it, Do not operate.

(3) Beneficial effects of the present invention

The beneficial effects of the invention are mainly as follows: the transmission of control information is reduced, the success rate of nodes reaching transactions through games is improved, and the forwarding opportunity of data packets in the network is increased, thereby improving the transmission success rate and throughput of data packets, reducing Control overhead and packet average end-to-end delay.

The beneficial effects of the present invention come from the following three aspects:

(1) By adopting the new mechanism of "adaptive reduced packet digest", the digests of data packets that cannot be forwarded by transactions and lifetime field values are removed, thereby reducing the redundant control brought by these data packet digests transmission of information.

(2) By adopting the new mechanism of "adaptively combining SV-DP message and purchase message", part of the purchase message is reduced, and the header of this part of the purchase message does not need to be transmitted (although the data packet summary quantity field is added, this field The default length is only 16 bits, which is significantly smaller than the length of the purchase message header), thus reducing the control overhead.

(3) By adopting the new mechanism of "comprehensive consideration of trading income during the game", the sum of the income at the time of buying and the time of selling is used to replace the original income at the time of selling to make a positive judgment (that is, whether to judge whether it is greater than 0), so that some original transactions cannot be reached. The game can also reach a transaction, thereby improving the transaction success rate, increasing the chance of data packets being forwarded in the network, thus improving the success rate and throughput of data packet transmission, and reducing the average end-to-end delay of data packets.

Description of drawings

Fig. 1 is a typical message interaction and data packet transmission process in the GSCP method. It can be seen from this that the SV, DP list and the purchase information of the data packet m are transmitted in different control messages.

Figure 2 shows the structure of the DP-SV-BUY message. The DP-SV-BUY message is a new control message proposed by the present invention, which includes the DP list, the data packet summary in the SV, and the summary of the data packet requested to be purchased. After the messages are merged, the header of the message is provided with a field for storing the number of data packet summaries in the SV (the default recommended length is 16 bits).

Figure 3 is the basic flow of the new mechanism of "adaptive reduced packet digest".

Fig. 4 is the basic flow of the new mechanism of "adaptively combining SV-DP message and purchase message".

Figure 5 shows the basic process of the new mechanism of "comprehensive consideration of trading income when gaming".

6 is a schematic diagram of the composition of the opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention. The new routing method consists of logically sequential node encounter perception, game and data packet transmission, and transaction settlement. It consists of three new mechanisms, including "adaptive reduction of packet summaries", "adaptive merging of SV-DP messages and buying messages", and "comprehensive consideration of buying and selling income during gaming", all of which work in the gaming and packet delivery stages .

FIG. 7 is the basic operation flow of the low overhead and high transaction success rate opportunistic network routing method proposed by the present invention in the node encounter perception stage.

FIG. 8 is a basic operation flow of a node in the stage of game and data packet transmission in the opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention.

FIG. 9 is the basic operation flow of CCC in the transaction settlement stage in the opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention.

FIG. 10 is the basic operation flow of the common node in the transaction settlement stage in the opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention.

Detailed ways

(1) Preset

The low overhead and high transaction success rate opportunistic network routing method proposed by the present invention is preset as follows:

(1) When the network first started running, each node was set to have the same virtual currency value - 10000.

(2) When each node obtains data packets from other nodes, it needs to use a certain amount of virtual currency to purchase. During the purchase, the two nodes use the form of game to negotiate the price; the virtual currency value owned by the node after buying the data packet will be determined according to the price. The transaction price is reduced by paying the virtual currency to the other party. If the node's remaining virtual currency value is not enough to buy a data package, it cannot get the data package.

(3) In the process of each transaction data packet, there will be transmission and reception overhead, and the buyer and seller nodes will generate game costs, which need to be deducted from the virtual currency value of the buyer or seller node.

(4) There is a special node with a fixed location in the network - the transaction settlement center CCC as the transaction fee settlement agency. For each transaction of buying and selling data packets between nodes, CCC will charge the seller node a transaction fee.

(5) The initial value of the node encounter probability P _init = 0.5, the cost that the source node of each data packet pays for successfully forwarding the data packet to the destination node ω = 1, the maximum packet length L _max = 4096 bits, the transmission overhead of the data packet m T(m)=L _max /40960

, the receiving cost of data/packet m P(m)=L _max /40960, the cost of the buyer node in each round of bargaining game C _B (γ)=0.1, the cost of the seller node in each round of bargaining game C _S ( γ)=0.1, transaction cost factor σ=(V _B (m)-V _S (m)-T(m)-P(m))/2.2, transaction cost γ=(V _B (m)-V _S ( m)-T(m)-P(m))/2-σ, transaction cost parameter k=2-2γ/(V _B (m)-V _S (m)-T(m)-P(m)) .

(2) Implementation

The opportunistic network routing method with low overhead and high transaction success rate proposed by the present invention is composed of three stages of operations: node encounter perception, game and data packet transmission, and transaction settlement, which have a logical sequence relationship, including "adaptive and simplified data packet summary". , "adaptive merging of SV-DP messages and buying messages", "comprehensive consideration of buying and selling income when gaming" three new mechanisms, all of which work in the gaming and data packet delivery stages.

1. Node encounter perception

The main operations of the node encounter awareness phase are as follows:

P1-S1: Nodes in the network periodically broadcast hello messages to announce their existence, and the broadcast period is T _hello =3s.

P1-S2: If a node receives a hello message broadcast by other nodes, it first extracts the source node address of the message; then, in the DP list, it queries whether the encounter probability value with the node is 0 (the encounter probability value is 0). means never met); if it is 0, modify the encounter probability value to the initial value of the encounter probability P _init ; if it is not 0, modify the encounter probability value with the node according to formula (6). Finally, the current node generates an SV-DP message, loads the SV and DP list and other information into it, and then sends it to the opposite node.

P1-S3: If a node receives an SV-DP message from another node, it first extracts the source node address of the message; next, it queries the DP list to see if the encounter probability value with the node is 0; if it is 0 , then modify the encounter probability value to the initial value of the encounter probability P _init ; if it is not 0, modify the encounter probability value with the node according to formula (6).

2. Gaming and packet delivery

The main operations in the game and packet delivery phases are as follows:

P2-S1: Each node independently judges whether it has received SV-DP messages from other nodes; if so, it modifies the corresponding encounter probability value, and then executes the next step; if not, executes steps P2-S8: .

P2-S2: The current node adopts the new mechanism of "adaptively combining SV-DP message and purchase message" proposed by the present invention to generate a DP-SV-BUY message; then, the DP list is loaded into the DP-SV-BUY message.

P2-S3: The current node loads the digests of the data packets into the DP-SV-BUY message one by one, and uses the new mechanism of "adaptive and simplified data packet digest" proposed by the present invention in the process of loading, and loads the digest of a data packet into the DP -Before the SV-BUY message, it judges whether the value of the lifetime field of the data packet is > 1; if so, execute the next step; Steps P2-S5:.

P2-S4: The current node judges whether the encounter probability between itself and the destination node of the data packet < the encounter probability between the encounter node and the destination node of the data packet; if so, load the summary of the data packet into the DP-SV-BUY message, and then go to the step P2-S3:; if not, go to step P2-S3: directly.

P2-S5: The current node judges whether to request a purchase message from the opposite node; if yes, execute the next step; if not, send the DP-SV-BUY message to the opposite node, and then go to step P2-S8:.

P2-S6: The current node judges whether the DP-SV-BUY message can be loaded with a data packet purchase information (including the source address, serial number, and quotation of the data packet (the quotation is calculated according to formula (1)); The data packet purchase information is loaded into the DP-SV-BUY message (placed behind the SV and placed one by one), and then goes to steps P2-S5:; if not, the DP-SV-BUY message is sent to the opposite node (that is, sent node for SV-DP messages).

P2-S7: The current node loads all the data packet purchase information that cannot be loaded by the DP-SV-BUY message into a purchase message, and then sends the message to the opposite node.

P2-S8: The current node judges whether it has received the DP-SV-BUY message sent by other nodes; if yes, execute the next step; if not, go to step P2-S10:.

P2-S9: The current node retrieves and stores the DP list, SV and purchase information from the DP-SV-BUY message (the length of the DP list is proportional to the total number of nodes in the network; the number of packet summaries contained in the SV is in DP-SV-BUY There are records in the corresponding fields of the message header, and the length of each data packet summary and each purchase information is a fixed value); then, the quoted value is extracted from the purchase information and the sales income of the data packet is calculated based on it (the time of sale). The income is calculated according to formula (4)); then, using the new mechanism of "comprehensive consideration of trading income during gaming" proposed by the present invention, it is judged whether the buying income + selling income of the data package is > 0; if so, the transaction is agreed, and the The data packet is sent to the other party; if not, the transaction is rejected and no sending operation is performed.

P2-S10: The current node judges whether it has received a purchase message from other nodes; if yes, execute the next step; if not, go to steps P2-S12:.

P2-S11: The current node extracts the quoted value from the purchase information contained in the purchase request message and calculates the sale-time income of the data package based on it; Whether the income at the time of buying + the income at the time of selling is > 0; if so, agree to the transaction and send the data packet to the other party; if not, reject the transaction and do not do the sending operation.

P2-S12: The current node judges whether it has received data packets from other nodes; if so, store the data packets, and create a data packet summary corresponding to the data packet in the SV (including the source node of the data packet, the destination node, serial number, income at the time of purchase, etc.); then, generate a payment message (including the seller's node address, data package serial number, data package transaction price, etc.) and send the payment message to the data package's seller node; Next, Subtract the amount spent for purchasing the data package (that is, the transaction price of the data package) from your own virtual currency value; Enter the "revenue when buying" field of the entry corresponding to the data packet in the SV; if no data packets from other nodes are received, go to the next step.

P2-S13: The current node judges whether it has received a payment message from other nodes that corresponds to a data package sold by itself; if so, it generates a "data package sales record" message to record the transmission of the data package and receiving overhead, the value of the data packet to the buyer and seller nodes, and then store the “data packet sale record” in the pre-established “data packet sale record table”; go to step P2-S1:; if no other For the payment message sent by the node, go directly to step P2-S1:.

3. Transaction settlement stage

The main operations in the transaction settlement stage are as follows:

P3-S1: CCC periodically broadcasts a hello message, the message includes its address, and the broadcast period is T _CCC =3s.

P3-S2: If a node receives a hello message broadcast by CCC, it will determine whether it has a "packet sale record" that has not been reported to CCC; " into a newly generated "packet sell message", which is then sent to CCC; if not, no further action is performed.

P3-S3: If CCC receives a "packet selling message" from a node, it will take out all "packet selling records" from the message, and then use formula (5) to calculate the deducted amount according to these records. The cost is loaded into a newly generated "cost deduction message", and then the message is sent to the opposite node; and the deducted cost is added to the opposite node in the pre-established "node cost deduction table". In the corresponding "Total Expenses Deducted" table entry value.

P3-S4: If a node receives a "cost deduction message" sent by CCC, it will take out the cost value to be deducted carried in the message, and deduct the cost value from its remaining virtual currency value; if it does not receive it, Do not operate.

Claims (1)

1. An opportunistic network routing method with low overhead and high transaction success rate, characterized in that: it is composed of node operations in three stages of logically sequential node encounter perception, game and data packet transmission, and transaction settlement; The main operation of the node in the encounter perception stage is to perceive the encounter with other nodes by receiving hello or SV-DP message. SV-DP message is a kind of message formed by connecting the content of existing SV message and DP message; game The main operation of nodes in the stage of and data packet delivery is to conduct a bargaining game and transfer data packets after reaching a transaction; the main operation of nodes in the transaction settlement stage is to calculate and collect node fees according to the concluded transaction; the above game and data packet delivery stage also includes three Mechanisms: adaptively simplifying data packet summaries, adaptively combining SV-DP messages and buying messages, and comprehensively considering buying and selling income when gaming; The self-adaptive and simplified data packet digest mechanism is specifically as follows: before the node loads the data packet digest into the SV-DP or DP-SV-BUY message, the DP-SV-BUY message is to combine the existing SV message, DP message and Data packet purchase message - a message formed by concatenating the contents of the BUY message, first determine whether the value of the lifetime field of the data packet is > 1 and whether the probability of encountering itself with the destination node of the data packet is < the encountering node and the data packet. The encounter probability of the destination node; only when the "lifetime field value>1" and "the encounter probability between the current node and the data packet destination node < the encounter probability between the encounter node and the data packet destination node", the current node will the data packet The digest is loaded into the SV-DP or DP-SV-BUY message, so as to avoid loading the useless data packet digest and eliminate the redundant control information brought by it; The mechanism of the adaptive merging of SV-DP message and purchase message is as follows: if the current node receives the other party's SV-DP message before sending its own SV-DP message, it generates a DP-SV-BUY message and lists the DPs. , the data packet summary is loaded into this message; Then, judge whether the DP-SV-BUY message can hold the next data packet purchase information, that is, judge the header+DP list+SV+a data packet purchase information of the DP-SV-BUY message Whether the length of the control message is less than the maximum length limit of the control message; if it is, according to the destination node of the data packet in the other party's SV-DP message, the probability of encountering the destination node in the other party's DP list, and the relationship between the destination node and the destination node in its own DP list Encounter probability, determine whether to buy the other party's data package; if you want to buy, calculate the optimal price of the data package to be purchased under the game equilibrium; next, load the data package into the DP-SV-BUY message for purchase information, as much as can be loaded without exceeding the maximum length limit of the control message, thereby reducing the number of data packet purchase messages as a whole; The mechanism of comprehensive consideration of buying and selling income during the game is as follows: when a node purchases a data package through the game, it will save the income at the time of purchase, referred to as "buy-time income", which is essentially the cost of purchasing the data package, Its value is < 0; when other nodes want to buy the data package and send a quotation, the current node calculates the income of selling the data package according to the quotation, which is referred to as "sell income", and its value is > 0; then judge the buy income + Whether the income when selling is > 0; if so, accept the offer from the buyer node and agree to the transaction; otherwise, reject the transaction; in this way, since the income from buying and selling data packets is comprehensively calculated during the game, the total income of the current node is guaranteed. In the case of >0, it reduces the requirement for the profit when selling, increases the chances of the buyer and the seller to reach a transaction, can improve the transaction success rate, and increase the chance of data packets being forwarded, thereby promoting the increase of network throughput and the average end-to-end of data packets. end delay reduction.

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