KR20160049919A - Method for managing coordinator in wireless sensor network for minimizing sensor data losses - Google Patents

Abstract

Disclosed is a method for managing a coordinator in a wireless sensor network to minimize loss of sensor data. The method for managing a coordinator in a wireless sensor network according to an embodiment of the present invention comprises the steps of: determining a state of a main coordinator managed by a PAN coordinator; and starting, by the PAN coordinator, wireless communication with an auxiliary coordinator instead of the main coordinator when it is determined that the main coordinator is in an abnormal state.

Description

[0001] The present invention relates to a method for managing coordinator in a wireless sensor network for minimizing sensor data loss,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless transmission technology, and more particularly to wireless sensor network technology.

A wireless sensor network is a network that senses object recognition information and surrounding environment information through a sensor device of a sensor device and processes and manages sensor data by connecting the sensor device to the outside. to be. For example, it remotely senses and manages various status and environmental information such as temperature, humidity, illumination, and pressure. Particularly, it is useful for the management of areas or objects requiring human accessibility or constant measurement, monitoring, and control.

IEEE 802.15.4 LR-WPANs (Low Rate Wireless Personal Area Networks), one of the standards of wireless sensor networks, is a private area network (PAN) standard protocol for low-speed communication using low power. The standard defines a physical layer (PHY) and a media access control sub-layer (MAC). The IEEE 802.15.4 standard is a simple packet data protocol for simple wireless networks that supports data rates such as 250kbps and supports a star or peer-to-peer topology. It also supports Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) for channel access and supports 64-bit or 16-bit addresses.

According to one embodiment, a coordinator management method in a wireless sensor network is proposed to minimize sensor data loss.

A method of managing a coordinator in a wireless sensor network according to an exemplary embodiment includes a step of determining a state of a primary coordinator managed by a private area network (PAN) coordinator, , The fan coordinator starts wireless communication with the auxiliary coordinator instead of the main coordinator.

The step of determining the state of the main coordinator according to an embodiment of the present invention includes the steps of transmitting a control message for checking the state of the main coordinator to the main coordinator when the fan coordinator does not receive sensor data from the main coordinator for a predetermined interval A step of retransmitting a control message if the PAN coordinator fails to receive a response message for the control message from the main coordinator for a predetermined time, and if the number of retransmissions of the control message exceeds a predetermined maximum number of transmissions , And the fan coordinator determines that the main coordinator is in an abnormal state.

At this time, the control message may be a device keep-alive message. The control message may be a medium access control message transmitted from the medium access control layer. The control message may be a command frame whose command frame identifier is 0x0a.

According to another aspect of the present invention, there is provided a method of managing a coordinator in a wireless sensor network, the method comprising: transmitting a control message to an auxiliary coordinator managed by the fan coordinator when the pan coordinator determines that the state of the main coordinator is abnormal; The auxiliary coordinator transmits a response message to the fan coordinator and switches to the active mode; receiving and collecting sensor data from the sensor devices managed by the auxiliary coordinator switched to the active mode; And transmitting the sensor data collected by the auxiliary coordinator to the fan coordinator.

The control message is a message for controlling the auxiliary coordinator to start transmitting a beacon message to sensor devices, and may be a beacon transfer start message. The control message may be a medium access control message transmitted from the medium access control layer. The control message may be a command frame whose command frame identifier is 0x0b.

The coordinator management method in the wireless sensor network further includes a step of notifying the management server of an abnormal state of the main coordinator by the pan coordinator and a step of deleting information of the main coordinator after the pan coordinator transmits the control message to the auxiliary coordinator .

According to another aspect of the present invention, there is provided a method of managing a coordinator of a fan coordinator in a wireless sensor network, the method comprising: receiving sensor data during a period in which a pan coordinator is allocated to a main coordinator; checking whether sensor data exists in a receiving buffer; The method comprising: initializing a response message reception waiting time and a control message retransmission count value if sensor data does not exist; transmitting a control message to the main coordinator and increasing a control message retransmission count; Determining whether a response message is received from the main coordinator within a waiting time, and determining that the state of the main coordinator is normal upon receiving a response message within a maximum response message reception wait time.

The main coordinator state determination method of the fan coordinator includes checking whether the control message retransmission number exceeds the maximum control message transmission number if the pan coordinator does not receive a response message from the main coordinator within the maximum response message reception waiting time, And retransmitting the control message to the primary coordinator if the number of control message retransmissions does not exceed the maximum number of control message transmissions and determining that the primary coordinator is abnormal if the control message maximum number of transmissions is exceeded.

According to one embodiment, in a wireless sensor network environment sensitive to sensor data, the fan coordinator quickly detects an abnormal state of the main coordinator, and instead of the main coordinator, the auxiliary coordinator collects sensor data, thereby minimizing the loss of sensor data have.

1 is a structural diagram of a hierarchical wireless sensor network according to an embodiment of the present invention;
2 is a structural diagram of a wireless sensor network system according to an embodiment of the present invention.
FIG. 3 is a flow chart illustrating a process between a fan coordinator and a main coordinator according to an embodiment of the present invention;
FIG. 4 is a flowchart illustrating a process of processing between a fan coordinator and an auxiliary coordinator according to an embodiment of the present invention;
5 is a flowchart illustrating a process of determining a state of a main coordinator according to an exemplary embodiment of the present invention;
FIG. 6 is a structure diagram of a control message newly defined in a MAC control message according to an embodiment of the present invention; FIG.
7 is a frame structure diagram of a Device keep alive message according to an embodiment of the present invention.
8 is a frame structure diagram of a Beacon transfer start message according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention of the user, the operator, or the custom. Therefore, the definition should be based on the contents throughout this specification.

1 is a structural diagram of a hierarchical wireless sensor network according to an embodiment of the present invention.

Referring to FIG. 1, a hierarchical wireless sensor network according to an exemplary embodiment of the present invention includes a centered PAN coordinator 10, and each device is connected to a coordinator 20 or May be connected to a sensor device (30). The coordinator 20 and the sensor device 30 may be plural. For example, as shown in FIG. 1, a wireless sensor network includes three coordinators 20-1, 20-2, and 20-3 and six sensor devices 30-1, 30-2, 6, but it is to be understood that the present invention is not limited thereto. The coordinator 20 according to one embodiment may be a router device, and the sensor device 30 may be a terminal device.

The coordinator 20 collects sensor data from the sensor device 30 and transmits the collected sensor data to the fan coordinator 10. [ If the coordinator 20 is in an abnormal state, for example, the coordinator 20 can not perform a normal operation due to a poor radio communication state with the fan coordinator 10 or an error in the coordinator 20 , The coordinator 20 can not transmit the sensor data to the fan coordinator 10. Therefore, the loss of the sensor data occurs until the coordinator 20 is changed to the normal state. Particularly, since the sensor device 30 is connected to the coordinator 20, sensor data loss due to abnormal processing of the coordinator 20 is fatal in a wireless sensor network in which sensitive or important sensor data must be transmitted. Accordingly, the present invention proposes a technique capable of minimizing sensor data loss by detecting the abnormal state of the coordinator 20 as quickly as possible.

2 is a block diagram of a wireless sensor network system according to an embodiment of the present invention.

2, the wireless sensor network system includes a fan coordinator 10, a management server 12, a coordinator 20 including a main coordinator 22 and an auxiliary coordinator 24, , And a sensor device (30).

The PAN coordinator 20 configures a personal area network (PAN) and manages the main coordinator 22, the auxiliary coordinator 24, and the sensor device 30. Then, it processes the received sensor data and transmits it to the management server 12.

The management server 12 performs the sensor data monitoring function according to the wireless sensor network environment. The wireless sensor network environment is not limited to, for example, railroad, bridge, port, vehicle, and the like.

The coordinator 20 comprises a main coordinator 22 and an auxiliary coordinator 24. The main coordinator 22 synchronizes with the fan coordinator 10 by receiving a beacon message from the fan coordinator 10 and synchronizes with the fan coordinator 10 to receive the beacon message from the sensor device 30 in a guaranteed time slot (GTS) And transmits the sensor data collected to the fan coordinator 10. The auxiliary coordinator 24 synchronizes with the fan coordinator 10 and receives from the sensor device 30 on behalf of the main coordinator 22 after switching from the standby mode to the active mode when the main coordinator 22 is in an abnormal state Collects the data, and transmits it to the fan coordinator 10.

The sensor device 30 receives the beacon message from the upper device, for example, the coordinator 20 or the fan coordinator 10, and transmits the beacon message to the upper device after synchronizing with the beacon message. The sensor device 30 may include a plurality of sensor devices 30-1, 30-2, ..., 30-n as shown in FIG.

The hardware configuration of each component can be fabricated by combining a field-programmable gate array (FPGA) chip and a chip for wireless communication in a main configuration. In detail, it is possible to embed computer technology means including a processor and a memory storage device in an FFE semiconductor chip, and to selectively configure input / output devices for various user environments. In FIG. 2, Although the configuration of the devices is not separately shown, a processor and memories can be used to perform the functions of the present invention. In addition, a separate operating system and application software can be installed in the firmware for user convenience.

FIG. 3 is a flowchart illustrating a process of processing between a fan coordinator and a main coordinator according to an embodiment of the present invention.

3, when the main coordinator 22 is in an abnormal state 300, the fan coordinator 10 becomes a state 310 in which sensor data can not be received from the main coordinator 22. The abnormal state 300 may be, for example, a loss of radio communication state or a main coordinator fault.

If the PAN coordinator 10 fails to receive the sensor data from the primary coordinator 22 during the GTS interval allocated for the primary coordinator 22, the fan coordinator 10 transmits a control message for checking whether the primary coordinator 22 is in an abnormal state To the main coordinator 22 (330-1). The control message is, for example, a device keep alive (Device Keep Alive) message. The Device Keep Alive message may be a MAC frame transmitted from a Medium Access Control layer (MAC layer). The Device Keep Alive message frame structure will be described later with reference to FIG. Hereinafter, the control message is limited to the Device Keep Alive message, but the present invention is not limited thereto.

If the PAN coordinator 10 does not receive a response (Ack) message for the Device Keep Alive message from the main coordinator 22 for a certain period of time, it retransmits the Device Keep Alive message (330-2, ..., 330-n). If the number of retransmissions exceeds the preset maximum number of transmissions (MaxFrameRetries) 340, the pan coordinator 10 determines 350 that the main coordinator 22 is in an abnormal state, and instead of the main coordinator 22, (360).

FIG. 4 is a flowchart illustrating a process of processing between a fan coordinator and an assistant coordinator according to an embodiment of the present invention.

Referring to FIG. 4, the auxiliary coordinator 24 receives (400) a beacon message from the fan coordinator 10 and then performs an association procedure (402).

The auxiliary coordinator 24 may wait until the auxiliary coordinator 24 receives a message from the fan coordinator 10 to control the sensor devices 30-1 to 30-n to start transmitting the beacon message, mode) 404. The above-mentioned control message is, for example, a beacon transfer start (Beacon transfer start) message. The beacon transfer start message frame structure will be described later with reference to FIG. Hereinafter, the control message is limited to the Beacon transfer start message, but the present invention is not limited thereto.

The auxiliary coordinator 24 temporarily switches to the active mode 412 in order to periodically receive the beacon message from the fan coordinator 10. [ Specifically, when the state of the main coordinator is determined to be abnormal 406, the pan coordinator 10 immediately sends a beacon transfer start message to the auxiliary coordinator 24 (408). Upon receiving the beacon transfer start message, the auxiliary coordinator transmits a response (Ack) message to the fan coordinator 10 (410) and switches to the active mode (412).

Sub-coordinator 24 then transmits its beacon message to sensor devices 30-1, ..., 30-n (414-1, ..., 414-n). An association procedure and a GTS request procedure are performed 416 between the assistant coordinator 24 and the sensor devices 30-1 to 30-n.

The auxiliary coordinator 24 performs a GTS request procedure for the auxiliary coordinator 24 to the fan coordinator 10 according to the GTS request received from the sensor devices 30-1 to 30-n. The auxiliary coordinator 24 receives the sensor data 422-1 to 422-n from the sensor devices 30-1 to 30-n and collects the collected data 422 and supplies the sensor data to the fan coordinator 10, (426).

5 is a flowchart illustrating a process of determining a state of a main coordinator according to an embodiment of the present invention.

Referring to FIGS. 2 and 5, the PAN coordinator 10 performs initialization 500 for the PAN configuration and operates a timer (502). Subsequently, sensor data is received during the GTS interval allocated for the primary coordinator 22 (504). The fan coordinator 10 checks whether sensor data exists in the reception buffer (506). If sensor data exists in the reception buffer, the sensor data is transmitted to the management server 12 (508). On the other hand, if there is no sensor data in the reception buffer, the fan coordinator 10 performs an operation for checking the state of the main coordinator 22.

First, the PAN coordinator 10 initializes the response message reception wait time (WaitAckTime) and the control message retransmission count (TxNum) to zero (510). Then, the device keep alive message is transmitted 512 to the main coordinator 22 and the number of control message retransmission times TxNum is increased (514).

The fan coordinator 10 confirms whether the response message is received from the main coordinator 22 within the maximum response message reception wait time MaxWaitAckTime (WaitAckTime <MaxWaitAckTime) (516). If the pan coordinator 10 has received a response message from the main coordinator 22 within the maximum response message reception waiting time MaxWaitAckTime, it determines that the state of the main coordinator 22 is normal and waits for the response message reception wait time WaitAckTime and the control The message retransmission count (TxNum) is initialized to 0 (518). On the other hand, if the PAN coordinator 10 fails to receive a response message from the main coordinator 22 during the maximum response message reception waiting time MaxWaitAckTime, the control message retransmission count TxNum becomes the maximum control message transmission count MaxFrameRetries (TxNum > MaxFrameRetries) (520).

(WaitAckTime) to 0 to retransmit the Device keep alive message to the main coordinator 22 and to transmit the control message retransmission number (&quot; WaitAckTime &quot;) to the main coordinator 22 if the control message maximum transmission number (MaxFrameRetries) TxNum) (522). On the other hand, when the number of retransmissions exceeds the maximum number of transmission messages (MaxFrameRetries) of the control message, the fan coordinator 10 determines that the main coordinator 22 is abnormal and notifies the abnormal state to the management server 12 ).

Then, the fan coordinator 10 transmits a beacon transfer start message to the auxiliary coordinator 24 (526). Then, information of the main coordinator 22 is deleted (528), and radio communication with the auxiliary coordinator 24 is started (530).

6 is a structural diagram of a control message newly defined in a MAC control message according to an embodiment of the present invention.

Referring to FIG. 6, a newly defined MAC control message according to an exemplary embodiment conforms to the IEEE 802.15.4 standard. In the IEEE 802.15.4 standard, 0x0a ~ 0xff are defined as reserved. In the control message defined by the fan coordinator to know the state of the main coordinator, the value 0x0a of the reserved value is defined as the value of the device keep alive message (601). The pan coordinator is a control message defined in order for the auxiliary coordinator to start transmitting a beacon message to the sensor device, and defines a value 0x0b of reserved value as a beacon transfer start message value (602). Meanwhile, the above-described definitions are merely examples for facilitating understanding of the present invention, but are not limited thereto.

FIG. 7 is a frame structure diagram of a Device keep alive message according to an embodiment of the present invention, and FIG. 8 is a frame structure diagram of a Beacon transfer start message according to an embodiment of the present invention.

Referring to FIGS. 7 and 8, the device keep alive message 601 and the beacon transfer start message 602 according to an embodiment conform to the IEEE 802.15.4 standard. At this time, each of the control messages 601 and 602 is defined as a 1-byte Command Frame Identifier.

The embodiments of the present invention have been described above. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10: Fan coordinator 12: Management server
20: Coordinator 22: Main Coordinator
24: Auxiliary coordinator 30: Sensor device

Claims (13)

Determining a state of a primary coordinator managed by a personal area network (PAN) coordinator; And
If the main coordinator is determined to be in an abnormal state, the fan coordinator starts wireless communication with the auxiliary coordinator instead of the main coordinator;
Wherein the coordinator management method comprises the steps of: 2. The method of claim 1, wherein the step of determining the state of the main coordinator comprises:
Transmitting a control message to the main coordinator to check the status of the main coordinator if the fan coordinator fails to receive sensor data from the main coordinator during a predetermined interval;
Retransmitting a control message if the PAN coordinator does not receive a response message for the control message from the main coordinator for a predetermined time; And
Determining that the main coordinator is in an abnormal state if the number of retransmissions of the control message exceeds a preset maximum number of transmissions;
Wherein the coordinator management method comprises the steps of: 3. The method of claim 2,
Wherein the control message is a device keep-alive message. 3. The method of claim 2,
Wherein the control message is a medium access control message transmitted from a medium access control layer. 3. The method of claim 2,
Wherein the control message is a command frame having a command frame identifier of 0x0a. If the pan coordinator determines that the state of the main coordinator is abnormal, transmitting a control message to an auxiliary coordinator managed by the pan coordinator;
The auxiliary coordinator having received the control message in a standby state transmits a response message to the fan coordinator and switches to the active mode;
Receiving and collecting sensor data from the sensor devices managed by the assistant coordinator switched to the active mode; And
Transmitting the sensor data collected by the auxiliary coordinator to the pan coordinator;
Wherein the coordinator management method comprises the steps of: The method according to claim 6,
Wherein the control message is a message for controlling the auxiliary coordinator to start transmitting a beacon message to sensor devices, and is a beacon transfer start message. The method according to claim 6,
Wherein the control message is a medium access control message transmitted from a medium access control layer. 3. The method of claim 2,
Wherein the control message is a command frame having a command frame identifier of 0x0b. The method of claim 6, wherein the coordinator management method in the wireless sensor network
Notifying the management server of an abnormal state of the main coordinator by the fan coordinator; And
Deleting the information of the primary coordinator after the pan coordinator sends the control message to the secondary coordinator;
Wherein the coordinator management method further comprises: Receiving sensor data during a period allocated to the main coordinator by the fan coordinator;
Checking whether sensor data is present in the reception buffer, and initializing a response message reception waiting time and a control message retransmission count value if sensor data does not exist;
Transmitting a control message to the main coordinator and increasing the number of control message retransmissions;
Confirming whether a response message is received from the main coordinator within a maximum response message reception wait time after transmission of the control message; And
Determining that the state of the main coordinator is normal when receiving the response message within the maximum response message reception waiting time;
Wherein the coordinator management method comprises the steps of: The method of claim 11, wherein the main coordinator state determination method of the fan coordinator comprises:
Confirming whether the number of control message retransmissions exceeds the maximum number of control message transmissions if the PAN coordinator does not receive a response message from the main coordinator within the maximum response message reception waiting time;
The method of claim 1, wherein the coordinator comprises a plurality of coordinators. 13. The method of claim 12, wherein the main coordinator state determination method of the fan coordinator comprises:
Retransmitting the control message to the primary coordinator if the number of control message retransmissions does not exceed the maximum number of transmissions of the control message and determining that the primary coordinator is abnormal if the control message maximum number of transmissions is exceeded;
The method of claim 1, wherein the coordinator comprises a plurality of coordinators.

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