CN101895954B - Opportunistic network routing method based on incremental transmission of packet index - Google Patents

Abstract

The present invention relates to an opportunistic network routing method based on packet index incremental transmission, including seven steps in the two stages of node not meeting and node meeting, wherein: the node not meeting stage includes a step: periodic broadcast of Hello message; node The encounter phase includes six steps: node encounter perception, data packet sending with the destination node as the opposite node, SV message sending, Request message sending, data packet sending and processing, and Hello message broadcasting on demand. In the process of sending the data packet index information during the node encounter, the present invention only sends the incremental information of the packet index, thereby reducing resource consumption; it can not only reduce the end-to-end delay of the data packet, but also reduce the risk of packet loss ; No need for special control packets to realize the release of data packet information that has reached the destination node, avoiding the redundant overhead of global broadcasting and periodic sending of control packets; at the same time, by deleting the data packets that have reached the destination node, reducing storage overhead.

Description

A Routing Method for Opportunistic Networks Based on Packet Index Incremental Transfer

technical field

The present invention belongs to the field of using opportunistic network technology, and in particular relates to an opportunistic network that adopts a routing technology based on an epidemic mechanism and assigns an independent identifier to each node in the network.

Background technique

An opportunistic network is a self-organizing network that does not require a complete path between the source node and the destination node, and utilizes the encounter opportunities brought about by node movement to achieve communication, delay and fracture tolerance; it can Completing data transmission tasks in the case of network splitting is not only a specific form of networking, but also a new network communication technology. It is regarded as an important direction for the development of mobile Ad Hoc networks, and it is the realization of future ubiquitous networks (Ubiquitous Networks). and development are important.

Routing technology is a challenging and important part of opportunistic network architecture. So far, people have proposed a variety of routing methods with opportunistic network as the background condition, and these methods can be divided into four types: redundancy-based, utility-based, redundant-utility hybrid and active movement-based. As a subclass of redundancy-based routing methods, infection mechanism-based routing methods have attracted widespread attention in recent years and have been more and more deeply researched and applied. The main idea of the infection mechanism is to use the opportunity of nodes meeting in motion to transmit data packets hop by hop. The basic steps are as follows: 

(1) When node A and node B in the network meet ("encounter" refers to entering the communication range of each other), A uses SV (Summary Vector) message ("message" refers to an independent and complete information unit in the opportunistic network) The transmitted control packet or data packet, the SV message is used to load the index information of the data packet) to send B the index information of the data packet stored by itself ("the index information of the packet" refers to the symbolic information that can uniquely represent a packet);

(2) After receiving the SV message, B compares the data packet index information in it with the index information of its stored data packets, and determines the index information of the data packets that it has not yet stored;

(3) B loads the index information of the unexisted data packets into the Request message, sends the message to A, and requests A to send the data packets that it does not have;

(4) After receiving the Request message from B, A finds the data packet that B has but does not have according to the packet index information in the message, and then sends it to B.

Opportunistic network nodes using the infection mechanism need to use the "store-carry-forward" method to process data packets. When they do not meet other nodes, they will not delete the data packets, but carry them to move together.

The basic idea of the infection mechanism was originally proposed by Demers et al. . Epidemic Algorithms for Replicated Database Maintenance[C]. Proceedings of the Sixth Symposium on Principles of Distributed Computing, 1987:1-12), used for the management and maintenance of database information of different nodes in the network. Later, Vahdat and Becker improved the original infection mechanism to make it suitable for the discontinuous connection characteristics of opportunistic network topology, and based on this, they proposed the Epidemic Routing protocol (see literature: A. Vahdat, D. Becker. Epidemic Routing for partially connected ad hoc networks[R]. Technical Report CS-200006, Duke University, Durham, 2000), the infected routing protocol uses the "store-carry-forward" method to process packets, and uses the IMEP (Internet MANET Encapsulation Protocol) protocol (See literature: M. S. Corson, S. Papademetriou, P. Papadopoulos, V. Park, A. Qayyum. An Internet MANET Encapsulation Protocol (IMEP) specific-

ation[R].(draft-ietf-manet-imep-spec-01.txt,1999) As a node-meeting perception mechanism, when the nodes meet, the transmission of group index information and the forwarding of data packets are used to realize the data transfer in the network Hop-by-hop transfer can reliably transmit data in opportunistic networks without the help of prior topology information, and the end-to-end delay of packets is small. Based on the infection routing protocol, Ramanathan et al. proposed a prioritized infection (Prioritized Epidemic) routing protocol (see literature: R. Ramanathan, R. Hansen, P. Basu, R. Rosales-Hain, R. Krishnan. Prioritized Epidemic Routing for Opportunistic Networks[C]. Proceedings of the 1st ACM International MobiSys Workshop on Mobile opportunistic Networking, San Juan, 2007:62-66), using the calculated path cost to prioritize the data messages stored by the nodes, and according to Priority adopts different deletion and transmission strategies for data messages, and reduces network load by discarding relatively useless messages. Matsuda and Takine designed (p,q) infected ((p,q)-Epidemic) routing protocol (see literature: T. Matsuda, T. Takine. (p,q)-Epidemic Routing for Sparsely Populated Mobile Ad Hoc Networks[ J]. IEEE Journal on Selected Areas in Communications, Vol. 26, No. 5, 2008:783-793), using 2-Hop forwarding and traditional infection routing algorithm according to the network status, and adopting a method called The mechanism of "VACCINE" (see literature: Z. Haas, T. Small. A New Networking Model for Biological Applications of Ad Hoc Sensor Networks[J]. IEEE/ACM Trans. Networking, 2006, 14(1): 27-40 ) Eliminate packets that have reached the destination node in the node cache by broadcasting control packets to reduce storage overhead. Wang Xin et al proposed ARER (Adaptive Randomized Epidemic Routing) - an adaptive randomized infection routing protocol (see literature: Wang Xin, Shu Yan-Tai, Jin Zhi-Gang, Pan Qing-Fen, Lee Bu-Sung . Adaptive Randomized Epidemic Routing for Disruption Tolerant Networks[C]. Proceedings of the 5th International Conference on Mobile Ad-hoc and Sensor Networks, 2009:424-429), the protocol uses the expression W _ij = C ₁ · R _i ( T _s )+C ₂ p _ij +C ₃ TTL _ij calculates the weight value W _ij of data packet i after j -hop transfer (wherein, R _i ( T _s ) is the replication density, p _ij is the forwarding probability, TTL _ij is the survival time parameter, C ₁ , C ₂ , and C ₃ are preset constants), and according to the weight W _ij , the data packets are sorted in the process of forwarding and deletion to improve performance such as delay, and at the same time, the Hello message carries the arrived The grouped information of the destination node can be used by the meeting node to clean up the cache, but increasing the periodical Hello message will bring additional overhead. Li Feng and Wu Jie added the community structure detection function to the traditional infection routing protocol (see literature: Li Feng, Wu Jie. LocalCom: A Community-based Epidemic Forwarding Scheme in Disruption-tolerant Networks[C]. Proceedings of the 6th Annual IEEE Communications Society Conference on sensor, Mesh and Ad Hoc Communications and Networks, 2009:1-9), using local information to detect community structure and use it to improve data packet forwarding efficiency, but the difference in community structure will affect routing performance.

Judging from the content of the above literature and the current research status, since the infection routing protocol was proposed, research on its improvement and expansion has been going on, in the forwarding and management of data packets, the combination with other forwarding methods, and the expansion of network application scenarios. Some progress has been made in such aspects, but there are still redundant overheads in the links of encountering node perception, control packet sending, data packet forwarding, and node cache management, and this problem has not been effectively solved so far, and it has a great impact on the adoption of infection The performance of the routing method of the mechanism has an important influence, so there is a need for further research and improvement, and the present invention will propose an innovative solution to this problem.

To sum up, the existing infection mechanism-based opportunistic network routing methods have the following problems:

(1) When two nodes meet, they use the IMEP protocol to realize the meeting node perception function, using control messages such as Hello and Echo and two handshake mechanisms, which bring a certain amount of redundant overhead;

(2) When a node sends an SV message to the meeting node, the index information of the node cache group is indiscriminately loaded into the SV message, which may contain information that has been told to the other party, so the repeated sending and receiving of information will bring redundancy. extra expenses;

(3) When nodes meet, the operation sequence of the infection mechanism is to send SV message-send Request message-send the data packet requested by the other party. Since the sending of the data packet is arranged in the last link, it may bring some additional delay; In addition, nodes meet during movement for a limited duration, which also poses a potential risk of losing data packets;

(4) When publishing the information of the group that has arrived at the destination node, the existing routing method adopts the method of broadcasting a special control group or using the existing periodic control group (such as Hello message) to piggyback information, resulting in a certain degree of control Overhead redundancy.

In view of the above four problems, this patent application proposes to send only the increment of the group index information after the nodes meet, to send data packets first in the operation after the nodes meet, to use the Request message to carry the information of the destination node group as needed, and to use the hello message Four new mechanisms, such as the perception of nodes encountered, reduce the control overhead of nodes and wireless channel resources, shorten the end-to-end transmission delay of data packets, and reduce the storage overhead of nodes.

Contents of the invention

The object of the present invention is to propose an opportunistic network routing method based on packet index incremental transmission, in which the packet index incremental transmission is adopted, data packets are sent preferentially, and the information of the destination node packet is carried in the Request message as needed 4 new mechanisms, such as information and hello messages for meeting node perception, solve the problem of redundant overhead in the existing routing method based on infection mechanism in the process of meeting node perception and information transmission after node meeting, and reduce the packet end-to-end time Delay, and clear the data packet cache of the node to reduce the storage cost of the node.

The technical solution adopted to achieve the above purpose is as follows, that is, an opportunistic network routing method based on group index incremental transmission, including seven steps in the two stages of node not meeting and node meeting, in which: the node not meeting stage Contains one step: periodic broadcast of Hello messages; the node encounter phase includes six steps: node encounter awareness, data packet sending with the destination node as the opposite node, SV message sending, Request message sending, data packet sending and processing, and Hello message on demand broadcast; the seven steps are as follows:

1), the periodic broadcast of the Hello message is specifically:

a. The network layer of the node generates a Hello message, and loads the network address of its own network layer into the Hello message;

b. According to the set broadcast period, the node repeatedly broadcasts the Hello message with the network address of its own network layer within the range of 1 hop;

2). The node encounter awareness includes one of the following situations:

a. If a node receives the Hello message broadcast by another node, it determines that it has met the node;

b. If a node receives a data packet from another node whose destination node is its own, it determines that it meets the node; in this case, the MAC layer of the receiving node will share the MAC address of the sending node across layers to Its own network layer; the network layer of the receiving node searches out and stores the network address of the sending node according to the MAC address-network address correspondence;

c. If a node receives the SV (Summary Vector) message sent to itself by another node, it determines to meet the node;

3) The sending of the data packet in which the destination node is the opposite node is specifically:

a. After a node determines that it has encountered another node, it immediately searches the data packet whose destination node is the other party in the packet cache;

b. The node sends the searched data packets whose destination node is the other party to the other party one by one until the sending is completed, and then enters the next step; if no data packet is found whose destination node is the other party, then directly enters the next step;

4) The sending of the SV message is specifically:

a. After a node encounters another node and completes the destination node’s data packet sending step for the other node, it judges whether new data has been stored since the last encounter with the node according to the location flag in its own data packet cache group;

b. If a new data packet is stored, the node generates an SV message at the network layer and loads the index information of the newly stored data packet into the SV message and sends it to the other node; at the same time, record the latest stored The location of the data packet is used as a sign for the next judgment; (the location of the data packet can be indirectly represented by the index information of the data packet, or directly represented by the address of the cache space occupied by the packet.)

c. If no new data packet is stored, no SV message is sent;

5), the specific steps of sending the Request are:

a. After a node receives the SV message, by comparing the index information of the data packet, it searches out the index information of the data packet that the other node has but does not have, or/and the other node has but has reached the destination node;

b. The node generates a Request message at the network layer, and loads the searched index information of the above-mentioned data packet into the Request message and sends it to the other node; if the index information of the above-mentioned data packet is not found, the Request message is not generated and sent ;

6), the sending and processing of the data packets are as follows:

a. After receiving the Request message, a node sends the data packet requested by the other party to the other party according to the data packet index information in it; if the other node does not request to send the data packet, no data packet is sent;

b. According to the index information of the data packet provided in the Request message, the node deletes the data packet that has reached the destination node from the packet cache, but retains the index information of the deleted data packet, which is used to judge whether the node encountered in the future There are data packets that have reached the destination node;

7) The on-demand broadcast of the Hello message is as follows:

a. After a node perceives that it has encountered another node through step 2), and executes the above steps 3), 4), 5), and 6) in sequence, it will judge whether it has sent a data packet whose destination node is the other party, SV message, or Request message;

b. If the node does not send any data packets or control messages (including SV messages and Request messages) to the other node after performing steps 2) to 6), it will broadcast a message containing its own network address within 1 hop. Hello message to the peer node to report its own appearance.

The essence of the operation of the present invention in the node meeting stage is to send SV messages, Request messages and data packets during the node meeting period. There are the following three characteristics in the process of sending SV messages and data packets:

(1) The SV message only carries the increment of the data packet index information, that is, only the increment is sent;

(2) The data packet whose destination node is the other node is first sent to the other node after the nodes meet;

(3) The Request message sent by the node contains the index information of the data packets that have arrived at the destination node but are still stored in the cache area of the other node.

The main innovation of the opportunistic network routing method based on packet index incremental transmission proposed by the present invention lies in the design of packet index incremental transmission, priority transmission of data packets, carrying information and user information of packets that have reached the destination node in the Request message as needed Hello message implements 4 new mechanisms such as meeting node perception. The principles and operations of these new mechanisms are as follows:

(1) Incremental transmission of group index

In each SV message received by an opportunistic network node using the infection mechanism, only the difference between the content of the SV message received from the same node last time, that is, the increment of the group index, is essentially useful information. According to this principle, in the present invention, when a node sends an SV message to another node, record the position of the data grouping of the latest storage at present; After the SV message is sent for the first time, the index information of the new group is stored; in this way, only the increment of the group index can be transmitted, thereby shortening the length and quantity of the SV message (the SV message will not be sent when there is no new data group stored), And reduce the calculation amount of the other node's comparison operation, and reduce the overhead of wireless channels and node resources;

(2) Data packets are sent first

Due to the movement of nodes, the duration of node encounters in opportunistic networks is limited, which has a potential negative impact on the completion of the data packet sending process. In order to transmit as many data packets as possible within a limited meeting time, a mechanism of "data packet priority transmission" is proposed here, that is, when a node meets other nodes, it will immediately send the data packets whose destination node is the other node. to the other party, and then send the SV message to carry out the subsequent information transmission process. In this way, the limited node meeting time can be used to transmit data packets as much as possible, which can not only reduce the end-to-end transmission delay of the packet, but also help reduce the risk that the data packet cannot be sent due to insufficient node meeting time, and improve the success rate of packet transmission;

(3) Carry the index information of the group that has reached the destination node in the Request message as needed

Deleting packets that have arrived at the destination node from the data packet cache is an important way for nodes to manage the cache and reduce storage overhead, but before deleting a data packet, it must first be determined whether it has reached the destination node. At present, there are methods such as broadcasting and Hello message piggybacking in publishing the information of the node group that has reached the destination, but the globality of broadcasting and the periodicity of Hello messages will increase the control overhead.

In order to reduce the control overhead generated by publishing the data packet information that has arrived at the destination node, in the present invention, a mechanism that uses the Request message to carry the index information of the data packet that has reached the destination node on demand is proposed to publish the data packet information that has arrived at the destination node , so that no special control group is needed, and the problems of global broadcast and periodic transmission are also avoided. The specific implementation of this mechanism is as follows: After a node successfully receives the data grouping of the destination node sent by the meeting node, it will send the index information of these groups to the other party in the subsequent Request message, and the other party receives the index information After deleting these groups, but retaining their index information is used to judge whether the nodes encountered later have data packets that have reached the destination node; when a node receives the SV message sent by another node, it will compare the group index information, Find out the data packets that have reached the destination node; if it finds that the other node still has packets that have reached the destination node, it will inform the other party in the Request message. This can not only delete the data packets that have reached the destination node, save the storage space of the node; but also reduce the unnecessary transmission of control information and reduce the control overhead;

(4) Use the Hello message to perceive the meeting node

The existing routing method based on the infection mechanism uses the IMEP protocol as the default encounter node perception mechanism. This protocol uses control messages such as Hello and Echo and operations such as two handshakes, and there is a certain amount of redundant overhead. We found through research that, in fact, the Echo message is not necessary in the process of node encounter perception. A node receives other packets sent by another node, such as data packets, and can also perceive the occurrence of node encounter events. Based on this principle, we no longer use the IMEP protocol in the present invention, but only use periodic hello messages to sense the encounter nodes. The specific sensing process is as follows: when the network is running, the nodes periodically broadcast Hello messages locally. The period is T _Hello ; if a node receives the Hello message broadcast by another node, it judges that it has encountered the other party, so it starts the sending process of data packets and SV messages; if a node receives the destination node sent by another node is Its own data packet or SV message can also determine that it has encountered the other party, thereby starting the process of sending the data packet and SV message. If a node receives the Hello message but has no data packet and SV message to send to the other node, it broadcasts a Hello message to report its own appearance to the other node.

In the process of the specific application of the present invention, the opportunistic network based on packet index incremental transmission proposed by the present invention can be realized through software programming combined with hardware conditions according to the rules and methods determined in the above-mentioned 2 stages and 7 steps routing method.

The present invention has the following beneficial effects:

1. During the transmission of data packet index information during the node encounter, only the incremental information of the packet index is sent, which reduces the amount of information sent, thereby reducing the consumption of wireless channel bandwidth and node resources;

2. After a node encounters other nodes, it first sends data packets whose destination node is the other node, which can not only reduce the end-to-end delay of data packets, but also reduce the risk of packet loss due to the limited encounter time, which helps to improve transmission success rate;

3. Use the Request message to carry the index information of the data packet that has reached the destination node as needed, and can realize the release of the data packet information that has reached the destination node without special control packets, and also avoid the redundancy of global broadcasting and periodic sending of control packets. At the same time, by deleting the data packets that have reached the destination node, the number of data packets in the packet cache is reduced, and the storage overhead is reduced;

4. The hello message is used for encounter node perception instead of the Echo message. On the premise of ensuring the function and effect of encounter node perception, the types and quantities of control groups are reduced, and the control overhead is reduced.

Description of drawings

Figure 1 is a schematic diagram of the infection mechanism.

After node A meets node B, it first sends the SV message containing the data packet index information to B; B receives the SV message and obtains the index information of the data packet to be transmitted by A through comparison operation: Request=SV _A + SV _B ; then load these index information into a Request message and send it to A; A sends the data packet corresponding to the index information therein to B after receiving the Request message.

Fig. 2 is a schematic diagram of the steps of an opportunistic network routing method based on packet index incremental transmission.

The opportunistic network routing method based on group index incremental transmission is composed of 7 operation steps in two alternate stages of node not meeting and node meeting. These 7 steps are: ①Hello message periodic broadcast; The destination node is the data packet sending of the meeting node; ④SV message sending; ⑤Request message sending and processing; ⑥Data packet sending; ⑦Hello message broadcasting on demand.

FIG. 3 is a flow chart of node encounter perception designed in the present invention.

In the present invention, a node can perceive and determine that it has encountered other nodes by receiving the broadcast Hello message, receiving the data packet from the destination node for itself, and receiving the SV message sent to itself.

Fig. 4 is a flow chart of processing and sending of data packet index increment information.

The processing and sending operation of the incremental information of the data packet index mainly includes the steps of judging whether there is a new data packet stored, sending the new packet index information, and recording the position of the latest packet in the data packet cache.

Fig. 5 is a flow chart of sending a Request message.

After the node compares the data packet index information loaded in the SV message with the data packet index information stored by itself, it can obtain the index information of the data packet that needs to be sent and deleted by the other party; then, the node loads these information into the Request message and Send to the other party; if there is no information, the Request message will not be sent.

FIG. 6 is a flow chart of an on-demand broadcast operation of a Hello message.

The purpose of the on-demand broadcast of the Hello message is to inform the other node of its own appearance in time. When you receive the Hello message broadcast by the other node, but you have no destination node for the other party's data packet or SV message to send to the other party, you will broadcast a Hello message to let the other node perceive your own appearance, and provide subsequent data for the other node. Packet sending provides conditions.

Detailed ways

The invention is applicable to the field of opportunistic networks adopting routing technology based on infection mechanism. A specific implementation method is: in an opportunistic network using infection-based routing technology with no less than 3 nodes, the nodes are in intermittent or long-term motion, and there is data to be transmitted between them. In the process of data transmission, the opportunistic network routing method based on packet index incremental transmission proposed by the present invention can be used, through the incremental transmission of packet index designed by the present invention, priority transmission of data packets, and on-demand carrying of Request messages to achieve the purpose Mechanisms such as node grouping information and meeting node perception using Hello messages reduce control overhead, reduce data packet end-to-end delay, and reduce node storage overhead while achieving successful data packet transmission. In the present invention, the value of the broadcast period T _Hello of the Hello message can be set according to specific _network conditions. The save value can be set to 1 second.

Claims (1)

1. An opportunistic network routing method based on packet index incremental transmission, characterized in that: seven steps in two stages including node not meeting and node meeting, wherein: node not meeting stage includes a step: Hello message periodicity Broadcasting; the node encounter phase includes six steps: node encounter awareness, data packet sending with the destination node as the opposite node, SV message sending, Request message sending, data packet sending and processing, and Hello message broadcast on demand; the seven steps are as follows: 1), the periodic broadcast of the Hello message is specifically: a. The network layer of the node generates a Hello message, and loads the network address of its own network layer into the Hello message; b. According to the set broadcast period, the node repeatedly broadcasts the Hello message with the network address of its own network layer within the range of 1 hop; 2). The node encounter awareness includes one of the following situations: a. If a node receives the Hello message broadcast by another node, it determines that it has met the node; b. If a node receives a data packet from another node whose destination node is its own, it determines that it meets the node; in this case, the MAC layer of the receiving node will share the MAC address of the sending node across layers to Its own network layer; the network layer of the receiving node searches out and stores the network address of the sending node according to the MAC address-network address correspondence; c. If a node receives the SV (Summary Vector) message sent to itself by another node, it determines to meet the node; 3) The sending of the data packet in which the destination node is the opposite node is specifically: a. After a node determines that it has encountered another node, it immediately searches the data packet whose destination node is the other party in the packet cache; b. The node sends the searched data packets whose destination node is the other party to the other party one by one until the sending is completed, and then enters the next step; if no data packet is found whose destination node is the other party, then directly enters the next step; 4) The sending of the SV message is specifically: a. After a node encounters another node and completes the destination node’s data packet sending step for the other node, it judges whether new data has been stored since the last encounter with the node according to the location flag in its own data packet cache group; b. If a new data packet is stored, the node generates an SV message at the network layer and loads the index information of the newly stored data packet into the SV message and sends it to the other node; at the same time, record the latest stored The location of the data grouping is used as a sign for the next judgment; c. If no new data packet is stored, no SV message is sent; 5), the specific steps of sending the Request are: a. After a node receives the SV message, by comparing the index information of the data packet, it searches out the index information of the data packet that the other node has but does not have, or/and the other node has but has reached the destination node; b. The node generates a Request message at the network layer, and loads the searched index information of the above-mentioned data packet into the Request message and sends it to the other node; if the index information of the above-mentioned data packet is not found, the Request message is not generated and sent ; 6), the sending and processing of the data packets are as follows: a. After receiving the Request message, a node sends the data packet requested by the other party to the other party according to the data packet index information in it; if the other node does not request to send the data packet, no data packet is sent; b. According to the index information of the data packet provided in the Request message, the node deletes the data packet that has reached the destination node from the packet cache, but retains the index information of the deleted data packet, which is used to judge whether the node encountered in the future There are data packets that have reached the destination node; 7) The on-demand broadcast of the Hello message is specifically: a. After a node perceives that it has encountered another node through step 2), and executes the above steps 3), 4), 5), and 6) in sequence, it will judge whether it has sent a data packet whose destination node is the other party, SV message, or Request message; b. If the node does not send any data packets or control messages including SV messages and Request messages to the other node after performing steps 2) to 6), it will broadcast a message containing its own network address within the range of 1 hop. Hello message, to report its own appearance to the other node.

Images