KR101264908B1 - Data delivery method of Law-power 6LoWPAN protocol - Google Patents

Abstract

The present invention relates to a data transfer method of a low-power 6LoWPAN protocol, which enables active routing considering the energy of all sensor nodes, and ensures reliability by sending a response message without overhead. When delivering fragment packets to all nodes on the hop, the ID-based fragment packet transmission method can be used to reduce the number of transmissions by reducing the number of transmitted packets by increasing the available data space using simplified header information and reducing the number of transmissions. By using the LOAD routing protocol that is considered, it is possible to obtain the information of neighboring nodes in one routing without depleting the energy of a specific node, which not only saves the energy consumed for one-hop data transmission but also has severe energy constraints. Very suitable for wireless sensor network environment It is a useful invention that has one advantage.

Description

Data delivery method of Law-power 6LoWPAN protocol

The present invention relates to a data transfer method of the 6LoWPAN protocol, and more particularly, in the routing process, active routing can be considered in consideration of energy of all sensor nodes, and reliability is ensured by sending a response message that does not incur overhead. In addition, the low power 6LoWPAN protocol data transmission method saves transmission energy by increasing the available data space and reducing the number of transmitted packets by using simplified header information when delivering fragmented packets to all nodes on one-hop or multi-hop. It is about.

The development of information communication technology and the revolution of new information technology called ubiquitous computing have increased the necessity of wireless sensor network. The wireless sensor network is used as a medium for collecting various information after numerous sensor nodes with memory, battery, and hardware resources with limited computing capability are installed in a specific environment to form a network.

Recently, research is being actively conducted on IP-based USN (Ubiquitous Sensor Networks), which is highly compatible with existing Internet networks based on wireless sensor networks. IP-USN is one of the ubiquitous technologies for the purpose of providing continuous service by connecting a network to all things anytime, anywhere. It is a base technology that collects environmental information through sensors and collects / manages real-time information through IP-USN. 6LoWPAN is a representative technology among IP-USN technologies. 6LoWPAN, a low-power, low-cost IP-USN technology based on IEEE 802.15.4, aims to upload IPv6 addresses and lightweight IP protocols to sensor nodes. It is a suitable technique.

As the main function of 6LoWPAN, fragment and recombination techniques have been proposed to use large amounts of IPv6 data in wireless sensor networks, but many fragment transmissions occur due to the nature of fragmentation transmission, which seriously affects power loss of sensor nodes. Therefore, in addition to reducing the load on the sensor node, we consider the method of reducing the number of fragment packet transmissions to save energy.

Another feature provided by 6LoWPAN is the LOAD routing protocol. This protocol performs the operation of searching and determining the path to deliver the data sensed by the sensor node to the destination node, and only the destination node receives the path response message for the path selection method by the shortest distance and for the purpose of reducing head. send. Although the path setting is simplified and optimized, the selected path is almost unchanged, and the energy consumption imbalance occurs at the level of the entire sensor network because only specific nodes are transmitted during data transmission. This can lead to energy depletion of certain nodes as well as disruption of the network as a whole, requiring efficient management of sensor node energy distribution and proposals of energy decision-making methods and reliable routing methods for reliable data transmission. do.

Fragmentation divides large sized data into several pieces.Fragmentation function provided by Adaptation Layer applying 6LoWPAN protocol divides large sized IPv6 data into size that meets IEEE 802.15.4, and transmits fragmented frame at receiving side. Combining this refers to the ability to recover to complete data. Datagram Size, Datagram Tag, and Datagram Offset are used for single-headed header information for delivering fragmented packets and recombination. The Datagram Size represents the size of the complete IPv6 data before the fragment occurs, and the Datagram Tag represents the fragment unique number. The Datagram Offset is determined after the fragmentation occurs to ensure the order of the packets delivered in the wireless sensor network environment in which the fragmented packets have connectionless characteristics, and to prevent duplicate reception.

1 shows the structure of a fragment header defined in RFC4944. Fragmentation provided by the adaptation layer performs the process of dividing and recomposing data and delivering the fragmented packet to the destination. In the overall process, the Adaptation Layer on the sending side is in a waiting state until receiving data from the IP layer. If an IPv6 data delivery request is received, the Adaptation Layer is divided into sizes that fit the payload space used for the entire IPv6 data. After adding the Firsc fragment header to the data, it is transmitted using the path information recorded in the routing table. After the first transmission, the remaining fragment fragments are also transmitted using the sequence fragment header. Even in the Adaptation Layer on the receiving side, the receiver waits until it receives data from the MAC layer. If the fragment packet having the First fragment header and the Sequence fragment header is repaired out of order, the recombination process is performed. For the recombination process, it is necessary to be able to identify what the original data of the fragmented cut is, to determine which part of the fragment, and to set an appropriate recombination time. Complete data can be recovered through the datagram tag and datagram offset value of the received header, which must be performed within a set time. Otherwise, all processing will be considered a failure and all data recombining will be discarded.

LOAD (6LoWPAN Ad hoc Routing Protocol) is a representative routing protocol suitable for ad hoc networks. It is a protocol that simplifies and optimizes the Ad-hoc On demand Distance Vector (AODV) protocol first proposed in the IETF intemet draft in 1997 to 6LoWPAN characteristics. . It is a request-based protocol that creates a route only when data needs to be sent to its destination. It uses EUI-64 or 16-bit addresses. Compared to AODV, the process of finding the route is simplified without using the destination sequence number to reduce the size of the control message. Also, to prevent message looping, only destination node sends RREP (Route Reply) message for RREQ (Route Reque st) message.

Figure 2 shows the message delivery flow of the LOAD routing protocol operating on 6LoWAN. The actual data is processed at the application layer of the source node or the edge node, but the intermediate nodes participating in the path setup or data transfer process reduce the overhead of sensor nodes because all operations are performed at the adaptation layer. The routing operation is performed to set a path when a node to which data is to be transmitted does not know path information of a destination node to receive data. If the source node does not have route information for delivery to the destination node, before transmitting data, the source node broadcasts a Route Request message (FIG. 3) to inform that the route information of the destination node is needed.

The Route Request message contains the RREQ ID, Route cost, and Originator / Destination Address information. The RREQ ID is used for message identification, and the route cost is increased by 1 for each hop delivered to the value required for the shortest route selection. Originator / Destination Address indicates the link layer address and destination link layer address of the requesting node.

Neighbors that receive this message look at the RREQ ID to determine if the message was previously delivered. If the message is received for the first time, determine who the destination is, and if not, create / record the Route Request Table and increase the route cost by 1 to perform the next transmission.

If the message has been received before, compare it with the route cost of the table, discard the larger one, and update the table information if it is smaller. This process is repeated until the destination node receives the Route Reque st message and stops transmitting when the destination node receives the Route Request.

The destination node sends a response by adding its information to the Route Reply message (FIG. 4). The Route Reply message is delivered in a unicast manner through the route selected by the Route Request message, and the intermediate nodes that receive this message search the table through the RREQ ID and find the source node with the recorded information. For route reply message forwarding, only nodes with route request table with the same RREQ ID will participate and create / record routing table using message information. This process is also performed until the source node receives a Route Reply message, and when the source node receives the message, the node knows the path of a possible destination node for data transmission.

The fragmentation scheme provided in the existing 6LoWPAN protocol not only has a drawback in that it consumes a lot of energy due to the nature of fragment packet transmission, but also sets up once if the sensor node cannot communicate when routing using the existing LOAD routing protocol. The path does not change. This is a problem that the proper energy distribution is not made, causing energy depletion of the specific node and affect the entire network.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances to solve various shortcomings and problems caused by the fragmentation scheme provided in the conventional 6LoWPAN protocol. The object of the present invention is to reduce the number of transmissions by adopting an ID-based fragment packet transmission method. The present invention provides a data transmission method of a low power 6LoWPAN protocol.

Another object of the present invention is to use the LOAD routing protocol in consideration of energy distribution in the ID-based fragment packet transmission method to obtain the information of neighbor nodes in one routing without depleting the energy of a specific node. It is to provide a data transfer method of the low power 6LoWPAN protocol to save energy consumed by the system.

It is another object of the present invention to provide a data transfer method of a low power 6LoWPAN protocol which is well suited for a wireless sensor network environment with high energy constraints.

The data transmission method of the low-power 6LoWPAN protocol of the present invention for achieving the above object comprises the steps of: a source node transmitting a Route Request message to an intermediate node; Generating, by the intermediate node receiving the Route Request message, a routing table and a Route Request table; Transmitting, by the intermediate node, a Route Request + Ack message to a source node; Transmitting, by the intermediate node, a Route Request message to a destination node; Generating, by the source node, a neighbor table; Generating, by the destination node, a routing table; Transmitting, by the destination node, a Route Reply + Table id message to an intermediate node; The intermediate node updating a routing table; Transmitting, by the intermediate node, a Route Reply + Table id message to a source node; Updating, by the source node, a routing table; Sending, by the source node, the first fragment to an intermediate node; The intermediate node generating a fragment table; Sending, by the quasi-node node, a first fragment to a destination node; Generating, by the destination node, a fragment table; Sending, by the source node, a second fragment to an intermediate node; Sending, by the intermediate node, a second fragment to a destination node; Sending, by the source node, the remaining fragments to an intermediate node; The intermediate node is characterized by comprising the step of transmitting the remaining fragments to the destination node.

According to the present invention, the ID-based fragment packet transmission method can be used to reduce the number of transmissions, and by using the LOAD routing protocol considering energy distribution, information of neighbor nodes can be obtained in one routing without depleting the energy of a specific node. This not only saves the energy consumed in one-hop data transmission, but also makes it particularly suitable for wireless sensor network environments with severe energy constraints.

1 is a diagram showing the structure of a fragment header defined in RFC4944,
2 is a diagram illustrating a data transfer flow in a routing process;
3 is a format diagram of a Route Request message;
4 is a format diagram of a Route Reply message;
5 is a format diagram of a Route Request message according to the present invention;
6 is a format diagram of a Route Reply message according to the present invention;
7 is a view showing a Route Request + Ack message delivery process according to the present invention;
8A is a diagram illustrating a route request process according to the present invention;
8b is a view showing a path response process according to the present invention;
9 is a view showing the structure of a fragment header according to the present invention;
10 is a flowchart illustrating a data transfer method of the low power 6LoWPAN protocol according to the present invention;
11 is a graph comparing the fragment packet transmission results of the present invention protocol and the existing protocol;
12 is a graph comparing energy change according to the present protocol and the existing protocol.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the data transfer method of the low power 6LoWPAN protocol of the present invention.

5 is a format diagram of a Route Request message according to the present invention, FIG. 6 is a format diagram of a Route Reply message according to the present invention, FIG. 7 is a diagram illustrating a Route Request + Ack message delivery process according to the present invention, and FIG. 8 is a diagram illustrating a route request process according to the present invention, FIG. 8b is a diagram illustrating a route response process according to the present invention, FIG. 9 is a diagram showing the structure of a fragment header according to the present invention, and FIG. 10 is a data of the present invention, a low power 6LoWPAN protocol. Transfer method operation flowchart, Figure 11 is a graph comparing the fragment packet transmission results of the present invention protocol and the existing protocol, Figure 12 is a graph comparing the energy change according to the present invention protocol and the existing protocol, the low power 6LoWPAN protocol of the present invention The data delivery method includes the steps of: a source node transmitting a Route Request message to an intermediate node; Generating, by the intermediate node receiving the Route Request message, a routing table and a Route Request table; Transmitting, by the intermediate node, a Route Request + Ack message to a source node; Transmitting, by the intermediate node, a Route Request message to a destination node; Generating, by the source node, a neighbor table; Generating, by the destination node, a routing table; Transmitting, by the destination node, a Route Reply + Table id message to an intermediate node; The intermediate node updating a routing table; Transmitting, by the intermediate node, a Route Reply + Table id message to a source node; Updating, by the source node, a routing table; Sending, by the source node, the first fragment to an intermediate node; The intermediate node generating a fragment table; Sending, by the quasi-node node, a first fragment to a destination node; Generating, by the destination node, a fragment table; Sending, by the source node, a second fragment to an intermediate node; Sending, by the intermediate node, a second fragment to a destination node; Sending, by the source node, the remaining fragments to an intermediate node; The intermediate node transmits the remaining fragments to the destination node.

Next, the data transfer method of the low power 6LoWPAN protocol of the present invention made as described above will be described in detail as an embodiment.

The routing protocol that uses the shortest path selection method in the data transfer of the existing 6LoWPAN protocol has a problem of causing energy consumption intensively only for specific sensor nodes due to the characteristics that the first selected path does not change easily. In addition, due to the nature of fragment packet transmission, it is necessary to deliver several to several tens of packets in order to send one IP data, which causes huge energy consumption to the node frame on the selected path and, in serious cases, stops the operation of a specific node, thereby preventing network fragmentation. It may be caused. In the data transmission method of the low power 6LoWPAN protocol of the present invention, active routing can be considered in consideration of energy of all sensor nodes in the routing process, and reliability is ensured by sending a response message without overhead. In addition, when forwarding fragment packets to all nodes on one hop or multi-hop, the simplified header information is used to increase the available data space and reduce the number of packets, thereby saving transmission energy. The data transfer method of the low power 6LoWPAN protocol of the present invention uses the messages shown in FIGS. 5 and 6.

Added A flag, Link Layer Self Address, Table id, and Remaining Energy to the existing Route Request message. The A flag is added when the route request message rate is received again as a bit indicating an Ack message. By using the characteristics of broadcasting that all neighboring nodes can receive the message in one transmission, when the node 1 of FIG. 1 receives the Route Request message and retransmits it to the next suction, it sets the A flag of the Route Request message. It retransmits by adding its own address, its created table id and energy level information. At this time, the S-node receiving the Route Request message containing Ack1 should know that the message was sent by the same RREQ ID and Route cost.However, if the A flag is set, it determines whose Ack is through the address of the Link Layer Self Address. Create / record the neighbor table shown in Table 1 below with Link Layer Self Address and Table id.

 Neighbor table        Item            Explanation  Table ID      Table unique number  Neighbor address      The address of the neighbor node

The node that sent the Route Request can know the neighbor's information without any additional routing process, and the neighbor table's information can be transmitted by using the table id information of the neighbor table without putting an address in the header when the fragment packet is to be transmitted one-hop. This also reduces the size of the fragment headers.

Nodes on the next hop that receive the same message at the same time know that this is the first message received because there is no Route Request information for the RREQ ID. Creates and records the route request table for the first node and the routing table as shown in Table 2 below. If additional messages with the same RREQ ID are received through different routes, the route cost and the remaining energy information are compared to the same cost. Select the node with the most remaining energy in the table and update the Route Request table. In this process, nodes that already have a low energy level are actively excluded from the path selection, and the Route Reply message can be directed to the source node through more energy nodes.

 Routing table        Item                     Explanation  Table ID  Table unique number  Destination address  Link layer address of the destination node  Next hop Address  Link layer address of the next node in the path to the destination  Status  Status information of the route  Lift time  Valid time before deleting or expiring a route (ms)

When the destination node receives the Route Request message, it adds a table id to the Route Reply message for the response and sends it to the source node. This information is recorded in all node routing tables on the selected route.

FIG. 8 illustrates an operation of routing the low power 6LoWPAN protocol of the present invention. FIG. 8A illustrates a path request process and FIG. 8B illustrates a path response process.

This table id is information used to create a fragment table after receiving the first fragment packet when the fragment packet is to be transmitted in multi-hop. By using the table id information of the routing table without sending an address in the fragment header transmitted through multi-hop, not only the fragment header size but also the number of transmissions can be reduced.

When the routing process is completed and the fragment packet needs to be transmitted, the first fragment packet is transmitted using the header defined in 6LoWPAN as it is, and the nodes receiving the packet have information on the fragment header to be omitted from the second fragment packet. It is used to generate the fragment table shown in Table 3.

       Fragment table       Item                 Explanation  Table ID          Table unique number  Datagram Size   Packet size before fragmentation (only destination node)  Datagram Tag        Identical identifiers between fragmented packets  Datagram Count  Information on the number of fragmented packets (Datagram Size ÷ Payload Size

FIG. 9 shows a header format proposed for transmitting fragment packets, and FIG. 10 shows the overall operation flow of the data delivery method of the low-power 6LoWPAN protocol of the present invention. The second and subsequent fragment packets are set by setting the dispatch value to OxFO. Used to convey. To compose this packet, omit the Mesh header used when transmitting fragment packet in multi-hop, indicate whether it is multi-suction or one-hop by M f1ag, and add by adding table id of Routing table.

In this case, the space of the omitted mesh header is used as payload, so the number of fragments and the number of transmissions can be reduced. After receiving this packet, the node in the path sees the M bit and refers to the routing table because if it is 0, one-hop transmission is required. The table id and datagram tag values are used to identify the packet, and the datagram offset and datagram size values are used when the destination node recombines. Datagram Count represents the total number of fragmented packets. Whenever fragment packet is delivered, it decreases by 1 and when it becomes 0, fragment table is deleted.

Next, in order to evaluate the performance of the data transmission method of the low-power 6LoWPAN protocol of the present invention, after implementing the 6LoWPAN protocol in the C language, IEEE 802.15.4 is mounted on the UTRC-SN110 sensor node manufactured by the ubiquitous new technology research center, and an adaptation layer Added. As a result of transmitting the IP data five times through the fragmentation scheme provided by the existing 6LoW PAN protocol and the low power 6LoWPAN protocol of the present invention, as shown in FIG. 11, the number of transmissions was reduced. When the address of the sensor node is used as the 16-bit address, the present invention reduces the number of transmission by about 7%, and when using the 64-bit address, more payload space can be secured, and the number of transmission is reduced by about 22%.

In order to evaluate the performance of the data transfer method of the low-power 6LoWPAN routing protocol of the present invention, the scenarios shown in Table 4 below were set, and the energy consumption of each transmission was quantitatively analyzed. Based on the power model of the simulator-based sensor node presented in Park, Jae-bok, "Development of Power Model of Sensor Network Node," the equation (battery available current-current consumed during transmission / reception) was used to calculate the residual energy.

The amount of available battery current is approximately 500mA. Based on the values measured in Park Jae-bok, "Development of the power model of the sensor network node," the average value is 17mA for transmission and 20mA for reception. This value is a relative value and was used to analyze the difference in energy consumption between the existing routing protocol and the present protocol.

      Evaluation item and analysis result   Packet   Transmission time   Number of data transfers   Selected path   Data 1    10:02          4   1-3-6-8-9   Data 2    10:09          5   1-4-6-8-9   Data 3    10:15          3   1-2-5-8-9   Data 4    10:25          4   1-2-6-7-9   Data 5    10:32          4   1-3-5-8-9   Data 6    10:40          5   1-4-6-7-9   Data 7    10:51          3   1-2-5-8-9   Data 8    10:59          4   1-3-6-7-9   Data 9    11:10          4   1-4-5-8-9

In the scenario set for the quantitative evaluation, each node maintains the routing table as 5 minutes, and each time Packet (x) is delivered, routing is performed to select a new route. Once the path is set, the data is transmitted as many times as the number of transmissions recorded in the table. As a result of applying the energy consumption according to the transmission / reception, the following energy consumption occurs according to the routing method.

In the existing LOAD routing protocol, the selected path was unchanged as long as the sensor node did not stop working even though the routing process was performed several times. As shown in FIG. 12, intensive energy consumption of specific nodes 2, 5, and 8 was performed. Could see. However, in the routing protocol of the present invention, it could be seen that the energy of all sensor nodes becomes equal as data transmission is performed.

While the present invention has been described as a preferred embodiment, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

Claims (1)

The source node sending a Route Request message to the intermediate node; Generating, by the intermediate node receiving the Route Request message, a routing table and a Route Request table; Transmitting, by the intermediate node, a Route Request + Ack message to a source node; Transmitting, by the intermediate node, a Route Request message to a destination node; Generating, by the source node, a neighbor table; Generating a routing table by the destination node; 10. A method for delivering data in a low power 6LoWPAN protocol, comprising: sending a Route Reply + Table id message to an intermediate node by a destination node;
The intermediate node updating a routing table; Transmitting, by the intermediate node, a Route Reply + Table id message to a source node; Updating, by the source node, a routing table; Sending, by the source node, the first fragment to an intermediate node; The intermediate node generating a fragment table; Sending, by the intermediate node, a first fragment to a destination node; Generating, by the destination node, a fragment table; Sending, by the source node, a second fragment to an intermediate node; Sending, by the intermediate node, a second fragment to a destination node; Sending, by the source node, the remaining fragments to an intermediate node; The intermediate node further comprises the step of transmitting the remaining fragments to the destination node.

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