KR20090102152A - Non-beacon mode zigbee sensor network system for low power consumption and network communication method thereof - Google Patents

Abstract

PURPOSE: A low-power Zigbee sensor network system of a non-beacon mode and a network communication method thereof are provided to prevent or minimize the network unstableness which is caused by the symmetrical power consumption of a parent node and a child node. CONSTITUTION: A network communication is made between a parent node(100) and a child node(200) which form a Zigbee sensor network system of a non-beacon mode. The child node provides polling request period information to the parent node when a network participation request is received. The parent node grasps the point of time of the polling request of the child node based on the polling request period information, and maintains a wake-up state only when the polling request is received from the child node as maintaining a sleep state for the rest time.

Description

Non-beacon mode Zigbee sensor network system for low power consumption and network communication method

The present invention relates to a low power Zigbee sensor network system and a network communication method according to the beacon unavailable mode, and more particularly, to reduce the wake-up time of the parent node constituting the Zigbee sensor network system to implement low power communication The present invention relates to a low power Zigbee sensor network system and a network communication method.

Recently, with increasing interest in the ubiquitous environment, research on sensor networks has been actively conducted. In the sensor network, a wireless personal area network (WPAN) method, ZigBee (ZigBee) is emerging as an optimal technology for implementing a low-power and ultra-low cost network. Such Zigbee is expected to be the center of office automation, factory automation, and home network construction. In addition, it can be usefully used as a sensor network solution because it is installed not only in homes and indoors, but also in areas where it is difficult for people to measure, such as forest fire detection, environmental changes, and disaster detection. In most of these applications, ZigBee devices will operate on a battery basis. Therefore, the most important factor in the sensor network will be low power consumption.

The Zigbee is a standard newly defined from the network layer by introducing a physical layer protocol (PHY) and medium access control (hereinafter referred to as 'MAC') of IEEE 802.15.4.

The stack structure of the Zigbee standard is composed of an application layer, a network layer, a media access control (MAC) layer, and a physical layer (PHY).

The physical layer (PHY) provides an interface between the MAC layer and the physical channel through radio firmware (RF Firmware) and radio hardware (RF Hardware) and applies the provisions of IEEE 802.15.4. The frequency band is 2.4GHz, 868 / 915MHz and the modulation method such as Offset Quadrature Phase Shift Keying (OQPSK) is applied, controlling the active and inactive state of the radio transceiver, detecting the energy of the selected channel, It is responsible for assigning frequencies and sending and receiving data.

The media access control (MAC) layer controls and handles all physical channels, applies the regulations of IEEE 802.15.4, and manages channel access.

The network layer establishes a star, cluster tree, or mesh network and selects a path for data transmission between devices.

The application layer provides an interface (API) between the network layer and the application layer and controls an application device or a Zigbee device defined by a user.

Devices used for the Zigbee communication can be classified by performance or function.

The performance can be divided into a full function device (FFD) and a reduced function device (RFD). The full-function device (FFD) may be used as any device among a Zigbee coordinator, a Zigbee router, and a Zigbee terminal device. Star, Peer to Peer, and Cluster-Tree network types are all supported.

Functions can be divided into coordinators, routers, and terminal devices. There is one coordinator for each network and is the basis for forming the network.

The coordinator is composed of a full-featured device (FFD), may also act as the router, and serves to assign a network address.

The router is a full-function device (FFD) as a component of the Zigbee network, and serves as a router for temporarily transmitting data from other devices.

The terminal device is usually composed of a reduced function device (RFD), can not act as a coordinator or a router, and a very simple function is implemented to support limited protocol functions.

 The reason for distinguishing devices in this way is to reduce the implementation cost. In particular, in the case of the terminal device is most installed, it is intended to make very cheap by saving only the necessary functions and discarding all the remaining functions.

In this case, the coordinator and the router become a parent node for the terminal device, and the terminal device becomes a child node for the coordinator or the router. The router becomes a child node for the coordinator and a parent node for the terminal device. In particular, the terminal device performs only a child node function and does not allocate a network address that is a parent node function.

Meanwhile, the ZigBee operates in two modes, a beacon mode network and a non-beacon mode network. The beacon available network operates in synchronization with nodes through periodic beacon messages, and the beacon unavailable network does not use a supplementary beacon message. Since the beacon unavailable network does not need to configure a superframe by periodically transmitting and receiving beacons, there is an advantage that can be implemented more simply. The beacon available mode and the structure or configuration of the superframe are not directly related to the present invention, which is well known to those of ordinary skill in the art to which the present invention is omitted.

1 shows a data transmission procedure in a conventional beacon unavailable network.

FIG. 1 (a) shows a data transmission procedure from a child node 20 to a parent node 10, and FIG. 1 (b) shows data from a parent node 10 to a child node 20. FIG. The transmission procedure is shown.

As shown in FIG. 1A, in the conventional beacon unavailable network, since the parent node 10 always operates in a wake up state, when data transmission is required in the child node 20, Data (Data) is immediately transmitted (transmitted) to the parent node 10 without an additional operation or confirmation process. At this time, the parent node 10 transmits an acknowledgment (ACK; Acknowledge) to the child node 20 indicating that the data (Data) transmitted from the child node 20 has been received.

As shown in FIG. 1 (b), in a conventional beacon unavailable network, even when data transmission to the child node 20 is required, the parent node 10 may poll the child node. If no data is available, data cannot be transmitted. The parent node 10 receives a polling request from the child node 20 and transmits an acknowledgment message Ack to the child node 20. The data is transmitted to the child node 20. Subsequently, the child node 20 transmits an acknowledgment message to the parent node 10 confirming that the data has been received.

As described above, the beacon unavailable mode is simpler than the beacon available mode, and there is an advantage that nodes do not need to be woken up or synchronized to process a beacon message periodically. However, since the parent node must guarantee a response to a polling request periodically generated from the child node and a randomly generated data transmission from the child node, the parent node should always wait for reception in a wake up state. This is illustrated in FIG. 2.

As shown in FIG. 2, the parent node should always wake up to respond to periodic polling requests with a period I and possibly data transmissions at the child node. This is very inefficient in terms of power consumption. In addition, power is asymmetrically consumed in relation to the child node. In other words, the parent node consumes more power than the child node. Asymmetrical power consumption of the parent node and the child node may cause instability of the network connectivity. Therefore, there is a need for symmetrical power consumption of the parent node and the child node and the need for implementing a low power network in the beacon unavailable mode.

Accordingly, an object of the present invention is to provide a low power ZigBee sensor network system and a network communication method according to the beacon unavailable mode that can overcome the above-mentioned conventional problems.

Another object of the present invention is to provide a low power Zigbee sensor network system in a beacon unavailable mode that can reduce power consumption, and a network communication method accordingly.

It is still another object of the present invention to provide a low power ZigBee sensor network system in a beacon unavailable mode that can prevent or minimize instability of a network, and a network communication method accordingly.

In accordance with an embodiment of the present invention for achieving some of the above technical problems, a parent node and a child node constituting a Zigbee sensor network system in a beacon mode (non-beacon mode) according to the present invention A network communication method between nodes includes: providing polling request period information to the parent node when a network participation request is made at the child node; The parent node determines the polling request time of the child node based on the polling request cycle information, maintains a wake up state only when polling request of the child node, and sleeps for the rest of the time. And in a maintaining manner, performing network communication with the child node.

The parent node based on the polling request period of the child node, the first time information that contains information about the time passed from the most recent polling request time point to the current wake-up time point and the next time the child node polls the next time It may have a structure of creating and updating a time table containing second time information having the remaining time information until the time of making a request, and determining whether the parent node wakes up and sleeps based on the time table.

 The creation and updating of the timetable may be performed during the wake up state of the parent node.

The polling request period information of the child node is included in a 'MLME-ASSOCIATE.request' message issued for network participation in an upper layer of a media access control (MAC) layer of the child node. The parent node may acquire the polling request cycle information of the child node in the process of processing the 'MLME-ASSOCIATE.indication' message transmitted from the MAC layer of the parent node to a higher layer.

The sensor network system may include a plurality of child nodes and at least one parent node.

The first time information includes a plurality of pieces of time information about time elapsed from issuance of recent polling requests of each of the plurality of child nodes to a wake-up time of the at least one parent node. The time information may include a plurality of time information regarding remaining time from the wake-up time of the at least one parent node to the polling request time points expected to be fastest in each of the plurality of child nodes.

The wakeup time of the parent node may be determined based on the earliest time information among a plurality of time information included in the second time information.

Data transmission from the parent node to the child node may be performed after the polling request of the child node, and data transmission from the child node to the parent node may be included in the polling request of the child node.

According to another embodiment of the present invention for achieving some of the above technical problems, the ZigBee sensor network system in the non-beacon mode according to the present invention, the information on the polling request period in the network participation request A plurality of child nodes each providing a network and performing network communication through a periodic polling request; The polling request time of each of the plurality of child nodes is grasped based on the information on the polling request periods provided from the plurality of child nodes, respectively. up) at least one parent node performing network communication with the child node in a manner of maintaining a state and maintaining a sleep state for the remaining time when a polling request of each of the plurality of child nodes is not expected. Equipped.

The at least one parent node includes a plurality of time information regarding time elapsed from the time of issuing recent polling requests of each of the plurality of child nodes to the wake up time of the at least one parent node. Second time information including time information and remaining time information from the wake-up time point of the at least one parent node to remaining polling time points expected to be fastest in each of the plurality of child nodes. Create and update a time table containing the information, and determine whether the at least one parent node wake up and sleep based on the time table.

The creation and updating of the timetable may be performed during the wake up state of the at least one parent node.

The wakeup time of the parent node may be determined based on the earliest time information among a plurality of time information included in the second time information.

The polling request period information of each of the plurality of child nodes is 'MLME-ASSOCIATE.request' issued for network participation in an upper layer of a media access control (MAC) layer of each of the plurality of child nodes. Is included in the message is delivered to the at least one parent node, the at least one parent node, in the process of processing the 'MLME-ASSOCIATE.indication' message delivered from the MAC layer of the at least one parent node to a higher layer The polling request period information of each of the plurality of child nodes may be obtained.

Data transmission from the at least one parent node to each of the plurality of child nodes is performed after a polling request of each of the plurality of child nodes, and from each of the plurality of child nodes to the at least one parent node. Data transmission may be performed by being included in a polling request of each of the plurality of child nodes.

According to the present invention, power consumption due to wake-up of the parent node can be reduced in network communication. Therefore, there is an advantage that a low power sensor network is possible. In addition, due to the symmetrical power consumption of the parent and child nodes, network instability can be prevented or minimized.

1 is a diagram illustrating a data transmission procedure in a conventional beacon unavailable network,

2 is a timing diagram illustrating a polling request of a child node and a wake-up state of a parent node according to the related art.

3 is a view showing a beacon unavailable ZigBee sensor network system and data transmission procedure according to an embodiment of the present invention,

4 and 5 schematically illustrate a procedure for network participation of the child node and parent node of FIG.

FIG. 6 is a diagram illustrating a timetable structure for determining a wake-up time according to a polling request period of a child node in a parent node of FIG. 3. FIG.

FIG. 7 is a timing diagram illustrating a process in which a parent node wakes up according to a polling request of a timetable and child nodes of FIG. 6.

* Description of the symbols for the main parts of the drawings *

100: parent node 200: child node

I: Polling request cycle P: 1st time information

I-P: 2nd time information Data: Data

Poll: Polling request

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, without any other intention than to provide a thorough understanding of the present invention to those skilled in the art.

In the present invention, the parent node refers to a coordinator or a router that is generally well known to those skilled in the art, and the child node refers to the terminal device. I shall do it. The terminal device may also be referred to as a sensor node, an end device, an end device, or a network device.

Figure 3 shows a beacon unavailable ZigBee sensor network system and data transmission procedure according to an embodiment of the present invention.

As shown in FIG. 3, the beacon unavailable ZigBee sensor network system according to an embodiment of the present invention includes a parent node 100 and a child node 200 that perform network communication through a predetermined protocol. At least one parent node 100 may be provided, and a plurality of child nodes 200 may be provided.

Basically, in the present invention, the parent node 100 does not always maintain the wake-up state, and maintains the wake-up state only when a polling request of the child node 200 is performed, thereby reducing power consumption and asymmetry with the child node. Minimize power consumption.

The child node 200 provides information on a polling request cycle when the network node joins the parent node 100, and performs network communication through periodic polling requests. The child node 200 is similar to the conventional operation except that the child node 200 provides information on the polling request period to the parent node 100 at the time of network participation request. That is, it operates similarly to the conventional method in that network communication with the parent node 100 is performed through a periodic polling request.

The parent node 100 receives information on a polling request cycle from the child node 200, and determines the polling request time of the child node 200 based on the information. In this way, the polling request of the child node 200 is maintained in a wake-up state, and the polling request of the child node 200 is maintained in a sleep state for the remaining time that is not expected. , Low power consumption. When a plurality of child nodes 200 are provided, including a case where one child node 200 is provided, a method of determining a polling request point of each of the child nodes 200 will be described later.

In the case of performing network communication as described above, one problem may occur. In the conventional case, when the child node 200 intends to transmit data (data packet) to the parent node 100, data is randomly transmitted without any special time constraint. This was possible in the conventional system because the parent node was always in the wake up state. However, in the configuration of the present invention in which the parent node 100 repeatedly wakes up and sleeps, the child node 200 cannot randomly transmit data to the parent node 100. In order to overcome this problem, according to an embodiment of the present invention, when data transmission is necessary in the child node 200, the data is transmitted to the parent node 100 including data to be transmitted at the polling request of the child node 200. Has a configuration to transmit. In other words, the child node 200 may include the transmission data in the polling request message and transmit the data to the parent node 100.

Polling request period information is exchanged between the child node 200 and the parent node 100 so that the parent node 100 knows the polling request time of the child node 200. ) And the data transmission procedure between the child node 200 is as follows.

First, the parent node 100 is normally in a sleep state, and when the polling request of the child node 200 is a wake-up state. Accordingly, the parent node 100 is in a receivable state (RxOn). At this time, a polling request message Poll is issued from the child node 200 and transmitted to the parent node 100. The process of transmitting messages and data between the child node 200 and the parent node 100 is well known to those skilled in the art.

The polling request message may include data Data to be transmitted from the child node 200 to the parent node 100. That is, polling data including data may be transmitted from the child node 200 to the parent node 100.

The parent node 100 receives the polling request, issues an acknowledgment (Ack) informing that it has been received, and transmits it to the child node 200. The parent node 100 transmits the data (Pended Data) to be sent to the child node 200.

When the child node 200 receives data from the parent node 100, the child node 200 issues an acknowledgment message (Ack) indicating that the data has been received and transmits it to the parent node 100.

When the series of processes is completed, the parent node 100 is in a sleep state and becomes incapable of reception (RxOff), and this incapacitation state and sleep state of the parent node 100 are determined by the child node 200. It continues until the next polling request.

As described above, as the parent node 100 does not always maintain the wake-up state and repeats the sleep state and the wake-up state, power consumption can be reduced as compared with the conventional art.

4 and 5 schematically illustrate a procedure for network participation of the child node and the parent node.

4 summarizes the procedure for the child node 200 to join the network, and FIG. 5 summarizes the procedure for the parent node 100 to participate in the network.

Other procedures other than those shown in FIGS. 4 and 5 are omitted when they are not necessary to describe the configuration of the present invention or when the prior art and the procedure are the same, but these procedures are included in the contents of the present invention. Is obvious.

As shown in FIG. 4, first, a network reset or initialization message (or command) (MLME−) from a higher layer of the MAC layer of the child node 200 to the MAC layer (MAC) for network participation. RESET.request) is issued. Here, the higher layer may be used to mean a higher layer of the MAC layer including the application layer and the network layer.

Accordingly, the MAC layer MAC of the child node 200 issues a result message (MLME-RESET. Confirm) for the network reset or initialization message (MLME-RESET. Request) to the higher layer. .

Thereafter, the higher layer and the MAC layer exchange a scan message (MLME-SCAN.request, MLME-SCAN.confirm) to find an activated network. Basically, all channels of the corresponding frequency among three frequency domains defined in the IEEE 802.15.4 standard are read. That is, it searches for the physical channels of the network already defined.

If considering the connection with the existing network, select the same physical channel, and to create an independent network, select a physical channel that is not activated. These network policies and channel selections are defined to be determined by the upper layers of the MAC for the flexibility of IEEE 802.15.4 networks.

IEEE 802.15.4 physically supports 27 different channels, and each channel is created with a different amount of energy. At this time, the child node to participate may perform an energy search (ED) for all channels provided by IEEE 802.15.4 according to the network policy. The energy search (ED) may be used to find channels in which the PAN network is not activated for network generation.

Subsequently, the higher layer of the child node 200 issues a message for network association, that is, a message for address allocation from the parent node 100 (MLME-ASSOCIATE. Request) and the MAC layer (MAC). To pass).

IEEE 802.15.4 consists of a 64-bit fixed address and a 16-bit address that can be received from a parent. The message (MLME-ASSOCIATE. Request) is a message for receiving a 16-bit address from a parent node with a 64-bit address. That is, a message for requesting an address. 16-bit addresses are known to use short data frames in the physical layer and are convenient for developing address-based routing protocols. When the child node 200 receives a 16-bit address from the parent node 100, the child node 200 is connected to the network.

Unlike the conventional method, in the child node 200, information about a polling request period of the child node 200 in a message (MLME-ASSOCIATE. Request) for an address request (Poll interval, or Poll period, hereinafter 'Poll interval) ') May be inserted into the parent node 100 and transferred to the parent node 100.

In addition, it is apparent that various methods for transmitting information on a polling request cycle from the child node 200 to the parent node 100 may be used.

Information about the polling request period (Poll interval) is inserted into the message (MLME-ASSOCIATE. Request) and delivered to the MAC layer (MAC) of the child node 200, the MAC layer of the child node 200 ( MAC) is transmitted to the physical layer (PHY) of the child node 200 through the 'PD-DATA.request' message. In addition, the physical layer (PHY) of the child node 200 is delivered to the physical layer (PHY) of the parent node 100 through the 'ASSOCIATION REQUEST' message.

As shown in FIG. 5, information on the polling request period (Poll interval) is obtained from the physical layer (PHY) of the child node 200 through the 'ASSOCIATION REQUEST' message, and the physical layer of the parent node 100. Is delivered to (PHY). In addition, the physical layer (PHY) of the parent node 100 is delivered to the MAC layer (MAC) of the parent node 100 through the 'PD-DATA.indication' message. The MAC layer of the parent node 100 transmits information on the polling request period to a higher layer of the parent node 100 through a 'MLME-ASSOCIATE.indication' message. Done.

At this time, the higher layer of the parent node 100 allocates a usable 16-bit address to the child node 200 according to the policy of the network (NWK) layer. In the process of processing the 'MLME-ASSOCIATE.indication' message, the parent node 100 can know the polling request cycle of the child node 200 requesting participation. Accordingly, the parent node 100 prepares a timetable based on the information on the polling request period (Poll interval), and grasps the polling request time of the child node 200. A method of preparing a time table and a method of identifying a polling request time point in the parent node 100 will be described with reference to FIG. 6.

Thereafter, the process of delivering the 'MLME-ASSOCIATE.response' message, the 'PD-DATA.reguest' message, and the 'ASSOCIATION RESPONSE' message in the parent node 100 are the same as in the related art. In addition, the transfer process of the 'PD-DATA.confirm' message, MLME-ASSOCIATE.confirm 'message of Figure 4 is the same as in the prior art. Therefore, further description is omitted.

By the above-described process, the network coupling between the child node 200 and the parent node 100 is completed. When there are a plurality of child nodes 200, the parent node 100 can know the polling request period of each of the child nodes 200 through the network joining process with each of the child nodes 200.

6 illustrates a timetable structure for determining a wake-up time according to a polling request period of the child node 200 in the parent node 100. Here, the wakeup time of the parent node 100 may mean an enable time of the MAC layer MAC of the parent node 100.

It is assumed that one parent node 100 is provided, and that the child node 200 is provided with n pieces (n is an arbitrary natural number). In addition, 'In' means a polling request period of each child node 200, 'Pn' means the time information flowed from the nth child node to the current wake-up time after the most recent polling request, ' In-Pn 'means time information remaining until the nth child node makes a recent polling request. 'T' means the earliest time information (T = min (In-Pn)) of time information remaining until each of the first to nth child nodes makes a recent polling request.

As shown in FIG. 6, the parent node 100, as described above, requests polling from a plurality of child nodes (Child node 1 to child node n, hereinafter referred to as '200') in a network joining process. Period information I1 to In is secured. The parent node 100 prepares a timetable based on the polling request period information I1 to In.

First time information P including a plurality of pieces of time information about time flows from the time of issuing recent polling requests of each of the plurality of child nodes 200 to the wake-up time of the parent node 100. ) Is stored in the timetable. In addition, the second time information including a plurality of time information for the remaining time from the wake-up time of the parent node 100 to the polling request time is expected to be the fastest at each of the plurality of child nodes; Save to timetable. The wakeup time of the parent node 100 is determined based on the time information T = min (In-Pn), which is expected to be fastest among the plurality of time information included in the second time information.

For example, in the case of the first child node (Child node 1), the polling request period is 'I1 = 10' and the first time information 'P1 = 3' of the first child node (Child node 1). Suppose That is, assume that the first child node (Child node 1) has passed '3' since the last polling request. In this case, the second time information I 1 -P 1 of the first child node 1 will be '7'.

Next, in the case of a second child node (Child node 2), assume that the polling request period is 'I1 = 4', and the first time information 'P2 = 0' of the first child node (Child node 1). . That is, suppose that the current time point is the polling request time point of the second child node. At this time, the second time information I2-P2 of the second child node 2 will be '4'.

In this way, the second time information is calculated to the nth child node n, the smallest value of the second time information is obtained, and the next wake up time is defined and stored in the time table.

Therefore, after the smallest time information (short time) of the second time information, the parent node 100 is in the wake-up state again. Of course, the parent node 100 remains in a sleep state for a time other than that. In this case, when only the first and second child nodes (Child node 1 and Child node 2) exist, the child node becomes 'T = 4' which is the smallest time information among the second time information. Accordingly, the parent node 100 wakes up again after a time corresponding to 'T = 4'.

At this time, the first time information P1 of the first child node 1 is updated with a value of '(P1 + T)% I1'. Of course, the first time information P2 of the second child node 2 is also updated with a value of '(P2 + T)% I2'. Second time information I 1 -P 1 of the first child node 1 and second time information I 2 -P 2 of the second child node 2 are also updated. .

In this way, even in the case of the nth child node n, the first time information Pn is updated such that '(Pn + T)% In' and the second time information In-Pn are updated. do.

Since the creation of the timetable and the updating of the timetable are performed by the parent node 100, it may be performed while the parent node 100 maintains the wake up state. That is, each time the parent node 100 wakes up, the parent node 100 calculates the corresponding values by using a timer and stores them in the timetable, and determines the wakeup time according to the determined 'T' value and returns to the sleep state.

FIG. 7 is a timing diagram illustrating a process in which a parent node wakes up according to a polling request of a timetable and child nodes of FIG. 6. In FIG. 7, it is assumed that two child nodes are provided for convenience of understanding.

As shown in FIG. 7, the polling request period of the first child node (Child node 1) is 'I1' and the polling request period of the second child node (Child node 2) is 'I2'. Here, the polling request period I2 of the second child node 2 has a larger value (longer period) than the polling request period I1 of the first child node 1.

When the time indicated by the arrow ↓ is a wake-up time of the current parent node 100, the wake-up time immediately before the parent node 100 is 3 of the second child node 2. The first polling request time point, and the current wake-up time of the parent node 100 is the fourth polling request time point of the first child node (Child node 1). Therefore, the first time information P1 of the first child node (Child node 1) at this time has a value of '0' and the first time information of the second child node (Child node 2) ( P2) is a time value from the time of the third polling request of the second child node 2 to the current time.

In addition, second time information I 1 -P 1 of the first child node 1 has a remaining time value from the present time to the fifth polling request time of the first child node 1. The second time information I2-P2 of the second child node 2 has a remaining time value from the present time until the fourth polling request time of the second child node 2. . Accordingly, a value 'T', which is the smallest time information among second time information of the first child node 1 and the second child node 2, is the second child node Child. The second time information of node 2) becomes 'I2-P2'. Therefore, when the current wake-up state ends and returns to the sleep state, the parent node 100 maintains the wake-up state again after a time of 'I2-P2'.

As described above, according to the present invention, power consumption according to wake-up of the parent node can be reduced in network communication in the beacon unavailable mode. In addition, due to the symmetrical power consumption of the parent and child nodes, network instability can be prevented or minimized.

The description of the above embodiments is merely given by way of example with reference to the drawings for a more thorough understanding of the present invention, and should not be construed as limiting the present invention. In addition, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the basic principles of the present invention.

Claims (16)

In the network communication method between a parent node and a child node constituting a Zigbee sensor network system in a non-beacon mode: Providing polling request cycle information to the parent node when the child node requests a network participation; The parent node determines the polling request time of the child node based on the polling request cycle information, maintains a wake up state only when polling request of the child node, and sleeps for the rest of the time. And in a maintaining manner, performing network communication with the child node. The method according to claim 1, The parent node based on the polling request period of the child node, the first time information that contains information about the time passed from the most recent polling request time point to the current wake-up time point and the next time the child node polls the next time Network communication, comprising: creating and updating a timetable containing second time information having time information remaining until the time of request, and determining whether the parent node wakes up or sleeps based on the time table Way. The method according to claim 2, The creation and updating of the timetable is performed during the wake up state of the parent node. The method according to claim 3, The polling request period information of the child node is included in a 'MLME-ASSOCIATE.request' message issued for network participation in an upper layer of a media access control (MAC) layer of the child node. Network communication method characterized in that the transmission. The method according to claim 4, And the parent node obtains the polling request cycle information of the child node in the process of processing a 'MLME-ASSOCIATE.indication' message transmitted from the MAC layer of the parent node to a higher layer. The method according to claim 3, The sensor network system comprises a plurality of child nodes and at least one parent node. The method according to claim 6, The first time information includes a plurality of pieces of time information about time elapsed from issuance of recent polling requests of each of the plurality of child nodes to a wake-up time of the at least one parent node. The time information includes a plurality of time information on remaining time from the wake-up time of the at least one parent node to the polling request time points expected to be fastest in each of the plurality of child nodes. Communication method. The method according to claim 7, The wakeup time of the parent node is determined based on the earliest time information among a plurality of time information included in the second time information. The method according to claim 3 or 8, Data transmission from the parent node to the child node is performed after the polling request of the child node, and data transmission from the child node to the parent node is included in the polling request of the child node. Communication method. In a Zigbee sensor network system in a non-beacon mode: A plurality of child nodes each providing information on a polling request cycle when the network joins a request, and each performing network communication through a periodic polling request; The polling request time of each of the plurality of child nodes is grasped based on the information on the polling request periods provided from the plurality of child nodes, respectively, and wakes up at the polling request time of each of the plurality of child nodes. up) at least one parent node performing network communication with the child node in a manner of maintaining a state and maintaining a sleep state for the remaining time when a polling request of each of the plurality of child nodes is not expected. Sensor network system, characterized in that provided. The method according to claim 10, The at least one parent node includes a plurality of time information regarding time elapsed from the time of issuing recent polling requests of each of the plurality of child nodes to the wake up time of the at least one parent node. Time information, and A timetable including second time information including a plurality of time information on remaining time from the wake-up time of the at least one parent node to the polling request time points expected to be fastest in each of the plurality of child nodes; And updating and determining whether the at least one parent node wakes up and sleeps based on the timetable. The method according to claim 11, The creation and updating of the timetable is performed during the wake up state of the at least one parent node. The method according to claim 12, The wake-up time of the parent node is determined based on the earliest time information of the plurality of time information included in the second time information. The method according to claim 10, The polling request period information of each of the plurality of child nodes is 'MLME-ASSOCIATE.request' issued for network participation in an upper layer of a media access control (MAC) layer of each of the plurality of child nodes. Sensor network system, characterized in that the message is delivered to the at least one parent node. The method according to claim 14, The at least one parent node receives the polling request period information of each of the plurality of child nodes in a process of processing a 'MLME-ASSOCIATE.indication' message transmitted from a MAC layer of the at least one parent node to a higher layer. Sensor network system, characterized in that obtained. The method according to claim 12 or 15, Data transmission from the at least one parent node to each of the plurality of child nodes is performed after a polling request of each of the plurality of child nodes, and from each of the plurality of child nodes to the at least one parent node. And data transmission is performed in a polling request of each of the plurality of child nodes.