KR102024578B1 - Method for scheduling duty cycle for underwater wireless sensor networks - Google Patents

Abstract

A method for adjusting the duty cycle in an underwater wireless sensor network is disclosed. In the method, the first wake-up transmitting node that wakes up first among the plurality of transmitting nodes receives the remaining energy amount information of each of the remaining transmitting nodes, and generates the remaining energy table using the received remaining energy amount information. Receiving, by a receiving node, the residual energy table from the first wake-up transmitting node, organizing a transmission schedule of the remaining transmitting nodes using the residual energy table; Each of the remaining transmitting nodes includes transmitting a data packet to the receiving node according to the transmission schedule.

Description

METHOD FOR SCHEDULING DUTY CYCLE FOR UNDERWATER WIRELESS SENSOR NETWORKS

An embodiment according to the concept of the present invention relates to a method for adjusting a duty cycle in an underwater wireless sensor network, and more particularly, to a method for avoiding packet collision in an underwater wireless sensor network.

The underwater wireless sensor network includes sensor nodes performing wireless communication using sound waves underwater and sink nodes communicating using sound waves and electromagnetic waves at the surface. The sensor nodes transmit the information detected by the sound wave to the sink node on the surface, and the sink node transmits the information received from the sensor nodes to the control tower on the ground using electromagnetic waves. When the sensor node does not exist in its communication range, the sensor node transmits the detected information over several hops to the sink node using a nearby sensor node.

 Since transmission characteristics in water, which are denser than air, have a narrow bandwidth, high attenuation, and a slow propagation speed, communication using sound waves is mainly used. However, communication using sound waves underwater does not include propagation delay, available bandwidth limitations, doppler spread, multipath, noise, high path loss, and low battery. There are limitations like power.

Due to this limitation, packet collisions in underwater networks are more deadly than packet collisions in terrestrial networks. For example, when performing additional recovery procedures such as packet retransmission due to packet collision, the slow propagation speed degrades the real-time of communication and causes more power consumption.

Korean Patent Laid-Open Publication No. 10-0810661 discloses an invention in which a radio resource allocation apparatus allocates time slots to transmission nodes using the residual energy amount of the transmission nodes. However, the prior art document still has a packet collision problem in an underwater network.

Patent Application Publication No. 10-0810661

The present invention has been made to solve the above problems, and the method for adjusting the duty cycle in the underwater wireless sensor network of the present invention is that the receiving node in consideration of the amount of energy remaining of each of the transmitting nodes in the vicinity The purpose is to determine the transmission schedule of the nodes.

A method for adjusting the duty cycle in the underwater wireless sensor network of the present invention for achieving the above object is the first wake-up of the plurality of transmitting nodes, the first wake-up transmitting node is the remaining of each of the remaining transmission nodes; Receiving energy amount information, generating a residual energy table using the received residual energy amount information, receiving node receiving the residual energy table from the first wake-up transmitting node, and receiving the receiving node; Composing a transmission schedule of the remaining transmission nodes using the residual energy table, and each of the remaining transmission nodes transmitting a data packet to the receiving node according to the transmission schedule.

The generating of the residual energy table by the first wake-up transmitting node may include: transmitting node ID from each of the remaining transmitting nodes whenever the first wake-up transmitting node wakes up each of the remaining transmitting nodes. And receiving a wake-up beacon packet including residual energy amount information, and generating, by the first wake-up transmitting node, the residual energy table using the wake-up beacon packet.

The receiving node receiving the residual energy table may include: receiving a wake-up beacon packet from the first wake-up beacon packet, meaning that the receiving node may receive a packet after the receiving node wakes up; Transmitting to the receiving node, the first wake-up transmitting node transmitting the residual energy table to the receiving node in response to the receiver wake-up beacon packet, and the receiving node receiving the residual energy table. It includes a step.

The transmitting of the residual energy table to the receiving node by the first wake-up transmitting node piggybacks and transmits a data packet together with the residual energy table.

The receiving node organizing the transmission schedule may include: receiving, by the receiving node, sorting the residual energy table in ascending order according to the remaining energy amount of the remaining transmitting nodes; Broadcasting a receiver wake-up beacon packet comprising, from the transmitting node in the entry, the corresponding transmitting node ID in turn as the next sender ID.

Each of the remaining transmitting nodes transmits a data packet to the receiving node according to the transmission schedule, wherein each of the remaining transmitting nodes receives the receiver wake-up beacon packet from the receiving node, and the receiver wake-up. Comparing the next sender ID included in the up- beacon packet with its own ID, and each of the remaining transmitting nodes transmits a data packet to a receiving node if the next sender ID and its ID match. .

Each of the remaining transmitting nodes further includes transitioning to a sleep mode if the next sender ID and its ID do not match.

The method for adjusting the duty cycle in the underwater wireless sensor network of the present invention means that when the receiving node is in sleep mode, the first transmitting node may receive a packet after the first transmitting node wakes up. Transmitting a wake-up beacon packet, and when the first transmitting node receives the wake-up beacon response packet from the second transmitting node, the first transmitting node determines that the first transmitting node is the first wake-up transmitting node. And the first transmitting node receives the ID of the second transmitting node and the remaining energy amount information of the second transmitting node from the second transmitting node, and receives the second transmitting node and the remaining energy amount information. Generating a residual energy table.

The method includes transmitting a receiver wake-up beacon packet to the first transmitting node, meaning that the receiving node can receive a packet after the receiving node wakes up; Transmitting the residual energy table to the transmitting node in response to the receiver wake-up beacon packet; receiving the residual energy table from the first transmitting node; and receiving the residual Organizing a transmission schedule of the second transmission node using an energy table, and transmitting the data packet to the receiving node according to the transmission schedule.

The method further includes transitioning to sleep mode if the receiving node does not receive a data packet from the transmitting node.

In the underwater wireless sensor network of the present invention as described above, the method for adjusting the duty cycle, the receiving node determines the transmission schedule of the transmitting nodes in consideration of the remaining energy amount of each of all the transmitting nodes in the vicinity, Even if they want to transmit packets at the same time, it is possible to provide an effect of avoiding packet collision.

In addition, avoiding packet collisions can increase the data throughput and reduce the energy consumption, thereby providing the effect of increasing the overall network life.

The detailed description of each drawing is provided in order to provide a thorough understanding of the drawings cited in the detailed description of the invention.
1 is a conceptual diagram illustrating packet collision in RI-MAC.
2 is a view showing the structure of an underwater wireless sensor network according to an embodiment of the present invention.
3 is a time table for explaining a method for adjusting a duty cycle in an underwater wireless sensor network according to an embodiment of the present invention.
4 illustrates a beacon signal and a data packet according to an embodiment of the present invention.
5 shows a residual energy table according to an embodiment of the present invention.
6 to 8 are flowcharts illustrating a method for adjusting a duty cycle in an underwater wireless sensor network according to an embodiment of the present invention.
9 is a flowchart illustrating an operation of a receiving node in an underwater wireless sensor network according to an embodiment of the present invention.

1 is a conceptual diagram illustrating packet collision in RI-MAC. Referring to FIG. 1, a receiver-initiated MAC (RI-MAC) is an asynchronous duty cycle scheme that adjusts wake-up schedules of transmitting nodes based on the wake-up time of a receiving node A. FIG. . In RI-MAC, the transmitting node (B, C, or D) always listens to the channel before transmitting the packet. If the receiving node (A) wakes up and transmits a beacon, the transmitting node (B, C, or D) receives the beacon and forwards the packet.

At this time, when multiple transmission nodes B, C, and D simultaneously transmit packets, packet collision may occur.

The present invention provides a method for adjusting a receiver-based dynamic duty cycle in which a receiving node can avoid packet collision by adjusting a transmission schedule of the transmitting nodes in consideration of the amount of remaining energy of each of the neighboring transmitting nodes in the underwater wireless sensor network. It is about.

In the present specification, the amount of remaining energy means the amount of energy remaining at the transmitting node at the present time.

Hereinafter, with reference to the embodiment and the drawings according to the present invention, the present invention will be further described.

2 is a view showing the structure of an underwater wireless sensor network according to an embodiment of the present invention. Referring to FIG. 2, the underwater wireless sensor network 10 uses a plurality of sensing nodes, namely, receiver nodes R and a plurality, arranged to provide information detected in a selected area using underwater acoustic links. It consists of the sender nodes (S1 to S8) of.

3 is a time table for explaining a method for adjusting a duty cycle in an underwater wireless sensor network according to an embodiment of the present invention. Referring to FIG. 3, network communication according to an embodiment of the present invention may be divided into two parts: a reception node sleep mode and a reception node wake-up mode.

Receive Node Sleep Mode

When the receiving node R is in the sleep mode, the first transmitting node A among the transmitting nodes A, B, and C having a packet to transmit to the receiving node R is the clear channel assessment (CCA). After)), if the channel is empty, it broadcasts a wake-up beacon (WB) packet.

4 illustrates a beacon signal and a data packet according to an embodiment of the present invention. Referring to FIG. 4, the WB packet may include a frame control field, a sender ID field, a receiver ID field, and a residual energy field. For example, the size of the frame control field is 2 octets, and the frame control field has a frame type, a fragmentation offset, a fragmentation start, a fragmentation end, and security information. It may include.

The size of the sender ID field is 1 octet and the sender ID field may include a transmitting node ID for identifying the transmitting node (A). The receiver ID field has a size of 1 octet, and the receiver ID field may include a reception node ID for identifying the reception node R. The size of the residual energy field is 1 octet, and the residual energy field may include residual energy amount information of the transmitting node A itself.

Referring again to FIG. 3, if there is a transmitting node that occurred earlier than the transmitting node A, the transmitting node A receives a wake-up beacon reply (WBR) packet from the first transmitting node. Can be received.

However, if the transmitting node A does not receive the WBR packet, the transmitting node A becomes the first transmitting node, that is, the first wake-up node, and generates a residual energy (RE) table. do. The first wake-up node A then collects the WB packets of the transmitting nodes B, C to wake up and updates the residual energy table.

As shown in FIG. 4, the WBR packet may include a frame control field, a sender ID field, a receiver ID field, and a first wake-up node ID field. For example, the sender ID field may include a transmitting node ID for identifying the transmitting node A, and the receiver ID field may include a receiving node ID for identifying the receiving node R. FIG. The size of the first wake-up ID node field is 1 octet, and the first wake-up node ID field may include a transmission node ID for identifying the transmission node A that occurred first.

5 shows a residual energy table according to an embodiment of the present invention. Referring to FIG. 5, the RE table may include a sender ID field, a receiver ID field, and a residual energy field corresponding to the sender ID. The first wake-up node A receives the remaining energy amount information of the transmitting nodes B and C targeting the same receiving node R, and generates an RE table based on the received remaining energy amount information. Manage network-wide schedules.

Referring back to FIG. 3, when the transmitting node B broadcasts the WB packet, the first wake-up node A updates the RE table with the sender ID, receiver ID, and remaining energy amount information stored in the WB packet. And transmits the WBR packet to the transmitting node (B).

For example, the WB packet may include a sender ID (e.g., an ID for identifying a transmitting node B), a receiver ID (e.g., an ID for identifying a receiving node R), and remaining amount of energy information (e.g., a transmitting node (e.g., The remaining energy amount information of B), and the WBR packet includes frame control information, a sender ID (e.g., an ID of a transmitting node A), and a receiver ID (e.g., an ID for identifying a receiving node R). ), And a first wake-up node ID (eg, ID of transmitting node A).

When the transmitting node C broadcasts the WB packet, the first wake-up node A updates the sender ID, the receiver ID, and the remaining energy amount information stored in the WB packet in the RE table and transmits the WBR packet to the transmitting node ( Send to C).

For example, the WB packet may include a sender ID (e.g., an ID of a transmitting node C), a receiver ID (e.g., an ID for identifying a receiving node R), and remaining energy amount information (e.g., a transmitting node C). Residual energy amount information), and the WBR packet includes frame control information, a transmitting node ID (e.g., an ID of a transmitting node A), and a receiving node ID (e.g., a receiving node R). ID), and a first wake-up node ID (eg, ID of transmitting node A).

The operation of updating the RE table by the first wake-up node A may include receiving the receiver wake-up beacon (RWB) packet from the receiving node R by the receiving node R. Until it is done.

Receive Node Wake-Up Mode

When the receiving node R wakes up, the receiving node R performs a CCA, and then broadcasts an RWB packet when the channel is empty.

As shown in FIG. 4, the RWB packet may include a frame control field, a sender ID field, a receiver ID field, a residual energy field, and a next sender ID. For example, the sender ID field may include an ID for identifying the transmitting node A, and the receiver ID field may include an ID for identifying the receiving node R. The size of the next sender ID field may be 1 octect, and the next sender ID field may be initially set to '-1'.

When the receiving node R broadcasts the RWB packet, the first wake-up node A piggybacks the data packet along with the RE table and transmits it to the receiving node R. As shown in FIG. 4, the data packet may include a frame control field, a sender ID field, a receiver ID field, and data. For example, the sender ID field may include an ID for identifying the transmitting node A, and the receiver ID may include an ID for identifying the receiving node R.

The receiving node R organizes the transmission schedules of the transmitting nodes B and C using the RE table transmitted from the first wake-up node A and transmits the organized schedule to the transmitting nodes B and C. ). Thus, the receiving node R communicates with the transmitting nodes B and C according to the schedule.

For example, the RE table is sorted in ascending order according to the remaining energy amount of each transmitting node, and the transmitting node at the top entry is required to transmit data first.

At this time, a transmitting node having a smaller amount of residual energy has a higher priority than a transmitting node having a higher amount of energy. If there are several transmitting nodes with the same amount of residual energy, the transmitting node first registered in the RE table has a higher priority.

By sequentially transmitting data from the transmitting node with a small amount of residual energy and going to sleep mode, the transmitting node optimizes its duty cycle according to a schedule while balancing the remaining energy amount of the transmitting nodes, It has the effect of reducing energy consumption.

The receiving node R, which has received data from the first wake-up node A, broadcasts an RWB packet containing the ID of the next transmitting node, in order to respond that it has received the data normally.

For example, in the RWB packet, the sender ID field may include an ID for identifying the transmitting node B, and the receiver ID field may include an ID for identifying the receiving node R. The size of the next sender ID field may be 1 octect, and the next sender ID field may be set to an ID for identifying the transmitting node C.

The first wake-up node A switches to the sleep mode in response to the RWB packet transmitted from the receiving node R. Among the transmitting nodes B and C that have received the RWB packet, the transmitting node (for example, the transmitting node B) that matches the next transmitting node ID transmits the data packet to the receiving node R.

The receiving node R, which has received the data packet from the transmitting node B, broadcasts an RWB packet containing the ID of the next transmitting node, in order to respond that it has normally received the data.

The transmitting node B switches to the sleep mode in response to the RWB packet transmitted from the receiving node R. Among the transmitting nodes B and C that have received the RWB packet, the transmitting node (e.g., transmitting node C) matching the next transmitting node ID transmits the data packet to the receiving node R.

The receiving node R, which has received the data packet from the transmitting node C, broadcasts an RWB packet containing the ID of the next transmitting node, in order to respond that it has normally received the data.

The transmitting node C switches to the sleep mode in response to the RWB packet transmitted from the receiving node R. The communication ends when the receiving node R no longer receives the data packet.

6 through 8 illustrate a flowchart for describing a method for adjusting a duty cycle in an underwater wireless sensor network according to an exemplary embodiment of the present invention. Referring to Fig. 6, the transmitting node wakes up (S100), listens for a channel to detect whether the channel is busy (S200), and if the channel is empty, broadcasts a WB packet to the channel. (S300).

After broadcasting the WB packet and listening to the channel (S400), if the WBR packet is not received (NO in S500), it is determined that the first node wakes up, that is, the first wake-up transmitting node (S600). The first wake-up transmitting node operates as shown in FIG. However, when the WBR packet is received (YES in S500), the remaining transmission nodes other than the first wake-up transmitting node operate as shown in FIG.

Referring to Fig. 7, the first wake-up transmitting node generates a RE table and listens to the channel (S620) and receives a WB packet from another transmitting node (YES in S630) based on the WB packet. The RE table is updated (S640). The first Wake-up transmitting node transmits the WBR packet (S650) and listens to the channel (S620).

However, if the first wake-up transmitting node does not receive the WB packet from another transmitting node (NO in S630), and receives the RWB packet (YES in S660), the first wake-up transmitting node receives data together with the RE table. The packet is transmitted to the receiving node (S670). When the first 'wake-up transmitting node receives the' RWB 'packet from the transmitting node (S680), it switches to the' sleep 'mode (S690).

Referring to FIG. 8, when the transmitting node receives the WBR packet in FIG. 6 and listens to the channel (S510) and receives the RWB packet (S520), the transmitting node compares its own ID with the next transmitting node ID included in the RWB packet. (S530). As a result of the comparison, if the next transmission node 'ID' and its 'ID' do not match (NO in S530), the channel continues to listen (S510). However, if the next transmission node ID and its ID match (YES in S530), the transmission node transmits the data packet to the reception node (S540) and listens to the channel (S550). When the transmitting node receives the " RWB " packet (S560), the transmitting node switches to the " sleep mode "

9 is a flowchart illustrating an operation of a receiving node in an underwater wireless sensor network according to an embodiment of the present invention. Referring to FIG. 9, when the receiving node wakes up (S710), listening to the channel (S720), and if the channel is empty, the receiving node wakes up a receiver wake-up beacon packet, which means that the receiving node can receive the packet. Broadcast (S730).

When the receiving node listens to the channel (S740) and receives a data packet from the first wake-up transmitting node (YES in S750), the receiving node includes a next transmitting node ID to respond that the data packet is normally received. -Broadcasts up beacon packets.

If the receiving node does not receive the data packet from the transmitting nodes for a predetermined time (NO in S750), the receiving node switches to the sleep mode (S770). The predetermined time may vary depending on the application service to be run in the network. For example, the predetermined time may be a value properly set by the network designer according to network characteristics.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

A, B, C; Sending node
R; Receiving node

Claims (10)

Receiving, by the first wake-up transmitting node which first wake-up from among the plurality of transmitting nodes, the remaining energy amount information of each of the remaining transmitting nodes, and generating a residual energy table using the received remaining energy amount information;
Receiving, by a receiving node, the residual energy table from the first wake-up transmitting node in a manner of piggybacking and transmitting a data packet together with the residual energy table;
The receiving node organizing a transmission schedule of the remaining transmitting nodes using the remaining energy table; And
Each of the remaining transmitting nodes transmitting a data packet to the receiving node in accordance with the transmission schedule. The method of claim 1,
The generating of the residual energy table by the first wake-up transmitting node may include:
Receiving, by the first wake-up transmitting node, a wake-up beacon packet including a transmission node ID and residual energy amount information from each of the remaining transmitting nodes each time each of the remaining transmitting nodes wakes up; And
Generating, by the first wake-up transmitting node, the residual energy table using the wake-up beacon packet. The method of claim 1,
The receiving node receiving the residual energy table,
After the receiving node wakes up, sending a receiver wake-up beacon packet to the first wake-up transmitting node, meaning that the receiving node can receive the packet;
The first wake-up transmitting node transmitting the residual energy table to the receiving node in response to the receiver wake-up beacon packet; And
And the receiving node receiving the residual energy table. delete The method of claim 1,
The receiving node organizing the transmission schedule,
The receiving node sorting the remaining energy table in ascending order according to the remaining amount of energy of the remaining transmitting nodes; And
In response to the receiving node, broadcasting a receiver wake-up beacon packet including a corresponding transmitting node ID in sequence from a transmitting node at the top entry of the residual energy table as a next transmitting ID; Method for adjusting the duty cycle. The method of claim 5,
Each of the remaining transmitting nodes transmits a data packet to the receiving node according to the transmission schedule.
Each of the remaining transmitting nodes receiving the recipient wake-up beacon packet from the receiving node and comparing its ID with the next sender ID included in the receiver wake-up beacon packet; And
And transmitting, by each of the remaining transmitting nodes, a data packet to a receiving node if the next sender ID and its ID coincide with each other. The method of claim 6,
And each of the remaining transmitting nodes transitions to a sleep mode if the next sender ID and its ID do not match. When the receiving node is in sleep mode, transmitting a wake-up beacon packet, which means that the first transmitting node may receive the packet after the first transmitting node wakes up;
If the first transmitting node does not receive a wake-up beacon response packet from the second transmitting node, the first transmitting node determines that it is the first transmitting node to wake up;
The first transmitting node receives the ID of the second transmitting node and the remaining energy amount information of the second transmitting node from the second transmitting node, and uses the second transmitting node and the remaining energy amount information to determine the remaining energy. Creating a table;
After the receiving node wakes up, sending a recipient wake-up beacon packet to the first transmitting node, indicating that the receiving node can receive the packet; And
The first transmitting node piggybacking and transmitting a data packet along with the residual energy table to the receiving node in response to the receiver wake-up beacon packet;
Method for adjusting the duty cycle in the underwater wireless sensor network comprising a. The method of claim 8,
The receiving node receiving the residual energy table from the first transmitting node;
The receiving node organizing a transmission schedule of the second transmitting node using the remaining energy table; And
And sending, by the second transmitting node, a data packet to the receiving node according to the transmission schedule. The method of claim 9,
Transitioning to a sleep mode if the receiving node does not receive a data packet from a transmitting node; further comprising: a duty cycle in an underwater wireless sensor network.

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