KR100665260B1 - How to wake up network device in Zigbee system - Google Patents

Abstract

The present invention relates to a wakeup method of a network device that can reduce power consumption in a Zigbee system. The present invention includes the steps of determining the error of the transmission period of the beacon frame in the network coordinator; Inserting an error of a transmission period of the determined beacon frame into the beacon frame; The network coordinator transmitting the beacon frame and the network device receiving the transmitted beacon frame; Storing the received beacon frame at the network device; And determining a point in time at which the receiver is turned on according to an error of a transmission period of the beacon frame inserted into the received beacon frame in the network device. According to the present invention, there is an effect of reducing power consumption in a Zigbee system requiring low power characteristics.

Description

Wakeup METHOD OF NETWORK DEVICE IN ZIGBEE SYSTEM

1 is a network configuration diagram of a general Zigbee system.

2 is a flow chart illustrating a wake up method of a network device in accordance with the present invention.

Figure 3 (a) is a structural diagram showing a typical beacon frame, (b) is a structural diagram showing an example of a beacon frame applied to the network device wake-up method according to the present invention.

* Description of Symbols for Main Parts of the Invention *

11: network coordinator 12: network device

The present invention relates to a wake-up method of a network device that can reduce power consumption in a Zigbee system. More specifically, the network device wakes up according to an error of a beacon frame transmission period determined by a network coordinator in a Zigbee system. The present invention relates to a wake-up method of a network device in a ZigBee system that can reduce unnecessary power consumption by enabling up.

ZigBee, a wireless personal area network (WPAN) technology, is a personal wireless network specification for 2.4GHz-based home automation and data featuring low power, low cost and low speed. Progressed. Referring to the above standard, Zigbee uses 2.4GHz, 915MHz, and 868MHZ frequency bands, and 250kbps (16 channels in 2.4GHz ISM band) and 40kbps / 20kbps (10 channels / 868MHz band in 915MHz band) for each frequency. Channels), and the modem method is DSSS (Direct Secure Spread Spectrum), which transmits data at a speed of 20 ~ 250kbps within a radius of 30m, and connects up to 255 devices to one wireless network. In addition, large-scale wireless sensor networks can be constructed indoors and outdoors.

ZigBee has the advantage of being able to consume very low power, compared to other WPAN technologies such as Bluetooth or Ultra Wide Band (UWB), and simplifying the configuration of wireless transceivers, enabling the lowest chipset price. It is a competitive short-range wireless communication technology in the area of vertical applications such as sensor networks.

For example, the introduction of ZigBee in lighting, fire detection, heating and cooling systems, etc., allows building managers to remotely manage and control building systems through portable devices rather than management offices.

1 illustrates an example of a configuration of a wireless private network according to the ZigBee technology, wherein a wireless private network is connected to one network coordinator 11 and the network coordinator 11 to transmit and receive data. It may consist of a network device 12.

In the configuration of such a wireless private network, the network coordinator 11 is provided in a main control device of a computer or a home network, and performs control of transmission and reception of data to and from a plurality of network network devices 12. 12) is the part that inputs and outputs actual data. In the case of home automation, heating, ventilation, air conditioner, security, light or sensor is applicable.

In such a Zigbee system, in order to implement a low power characteristic, the plurality of network network devices 12 operate with the receiver turned off for most of the time except for the time required for synchronization. In ZigBee, in such a short-range wireless private network, Zigbee operates in a superframe mode to be applied to a service having a short processing delay time according to an application. In this case, the network coordinator 11 is configured in advance. The superframe beacon frame is repeatedly transmitted at a time interval. At this time, a transmission period (also referred to as a "beacon period") of the beacon frame may be determined according to a beacon order determined by the network coordinator 11.

For example, the beacon period according to the beacon order may be determined as shown in Table 1 below. Table 1 below illustrates a case where the beacon period (basic beacon period) when the beacon order is 0 is 15360 ms.

Beacon Order Beacon Cycle 0 15360 One 30720 2 61440 3 122880 4 245760 5 491520 6 983040 7 1966080 8 3932160 9 7864320 10 15728640 11 31457280 12 62914560 13 125829120 14 251658240

As shown in Table 1, the beacon period increases as the beacon order is multiplied by a power of two times the beacon period when the beacon order is zero. That is, the beacon period is characterized by increasing exponentially as the beacon order increases.

On the other hand, the network device 12 receiving the beacon frame from the network coordinator 11 must turn on the receiver before the time when the beacon frame is received in order to receive the beacon frame. Since the beacon period of the beacon frame transmitted from the network coordinator 11 may have an error, the receiver should be turned on (wakeup) earlier than the time when the next beacon frame is expected to be received with a predetermined margin value. .

However, as shown in Table 1, since the beacon period increases exponentially, the error of the beacon period also increases exponentially. Table 2 below shows an example of the beacon period and the error when the error of the basic beacon period is 0.5 ms.

Beacon Order Beacon Cycle Error 0 15360.500 0.500 One 30721.000 1.000 2 61442.000 2.000 3 122884.000 4.000 4 245768.000 8.000 5 491536.000 16.000 6 983072.000 32.000 7 1966144.000 64.000 8 3932288.000 128.000 9 7864576.000 256.000 10 15729152.000 512.000 11 31458304.000 1024.000 12 62916608.000 2048.000 13 125833216.000 4096.000 14 251666432.000 8192.000

As shown in Table 2, when the error of the basic beacon period of the coordinator 11 is 0.500 ms, the error increases to 8192 ms when the beacon order is 14.

In general, since the network device 12 cannot know the exact error of the network coordinator 11, the network device 12 can periodically estimate the maximum error value of the network coordinator 11 to periodically receive the beacon frame. Should come on. Thus, a problem has arisen in that the time for which the receiver of the network device 12 is turned on is longer than the time for receiving the actual beacon frame. That is, since the predetermined margin value should be given in consideration of the error, the on time of the network device 12 is increased, resulting in a problem of increasing power consumption. This increase in power consumption is a fatal weakness in Zigbee, which is characterized by low power consumption.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and its object is to reduce unnecessary power consumption by allowing a network device to wake up according to an error of a beacon frame transmission period determined by a network coordinator in a Zigbee system. The present invention provides a wake-up method for a network device in a Zigbee system.

The present invention as a technical configuration for achieving the above object,

Determining an error in a transmission period of a beacon frame in the network coordinator;

Inserting an error of a transmission period of the determined beacon frame into the beacon frame;

The network coordinator transmitting the beacon frame and the network device receiving the transmitted beacon frame;

Storing the received beacon frame at the network device; And

Determining a time point at which the receiver is turned on according to an error of a transmission period of a beacon frame inserted into the received beacon frame in the network device;

It provides a wake-up method of a network device in a Zigbee system comprising a.

In one embodiment of the present invention, the step of determining the error of the transmission period of the beacon frame, the step of determining the error of the transmission period of the beacon frame according to the reference frequency error of the crystal oscillator included in the network coordinator desirable.

The determining of an error of a transmission period of the beacon frame may include determining an error of the transmission period of the beacon frame as a multiple of a unit backoff period, wherein the multiple of the unit backoff period is a crystal oscillator included in the network coordinator. It is more preferable to determine to have a value larger than the actual time error of the beacon frame transmission period due to the reference frequency error of.

In one embodiment of the present invention, the inserting into the beacon frame is preferably a step of defining an error in a transmission period of the beacon frame to any field in the beacon frame.

In addition, the step of inserting into the beacon frame, it is more preferable to define the error in the transmission period of the beacon frame to any field in the MAC payload included in the beacon frame.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiment of this invention is provided in order to demonstrate this invention more completely to the person skilled in the art to which this invention belongs.

2 is a flow chart illustrating one embodiment of a wake up method of a network device in a Zigbee system in accordance with the present invention. The present invention is characterized by transmitting error information about the period of the beacon frame transmitted by the network coordinator to the network device, and determines the time to turn on the receiver according to the error of the beacon frame period transmitted from the network coordinator . Due to this feature, the present invention can save time for the network device to wait on to receive a beacon frame, which is suitable for ZigBee, where the low power characteristics are important.

1 and 2, a wake-up method of a network device in a Zigbee system according to an embodiment of the present invention will be described.

In one embodiment of the present invention, first, an error of a transmission period of a beacon frame to be transmitted from the network coordinator 11 to the network device 12 (denoted as "beacon period" in FIG. 2) is determined (S11). The network coordinator 11 includes a crystal oscillator that provides a predetermined reference frequency for controlling the operation timing of the components included in the network coordinator 11. The transmission period of the beacon frame is also determined according to the reference frequency provided by this crystal oscillator. Therefore, when an error occurs in the reference frequency provided by the crystal oscillator, the error also occurs in the transmission period of the beacon frame.

The present invention can determine when the network device 12 wakes up by providing the network device 12 with the transmission period error of the beacon frame according to the reference frequency error provided by the crystal oscillator included in the network coordinator 11. It is characterized by.

That is, determining the error of the transmission period of the beacon frame to be transmitted from the network coordinator 11 to the network device 12 (S11) according to the reference frequency error of the crystal oscillator included in the network coordinator 11 The step of determining the error of the transmission period of. At this time, the error value of the transmission period of the beacon frame transmitted to the actual network device 12 is determined as a multiple of the unit backoff period, the multiple value of the unit backoff period is due to the reference frequency error of the crystal oscillator It is desirable to be larger than the time error value. The backoff period is an operating period of the network device 12. For example, in a Zigbee system using the 2.4 GHz band, the unit backoff period is 320 mW. That is, in a Zigbee system using the 2.4 GHz band, if the actual time error value of the beacon frame due to the reference frequency error of the crystal oscillator is 500 ms, 640 ms, which is twice the unit backoff period, is transferred to the network device 12. It becomes the transmission period error value of the beacon frame transmitted.

Next, the network coordinator 11 inserts the error of the transmission period of the beacon frame determined as described above into the beacon frame (S12). Inserting the transmission period error of the beacon frame into the beacon frame (S12), it is preferable that the step of defining the error of the transmission period of the beacon frame to any field in the beacon frame. In particular, the step of inserting into the beacon frame is more preferably a step of defining the error in the transmission period of the beacon frame to any field in the MAC payload included in the beacon frame.

3 is a structural diagram of a general beacon frame provided to explain the step (S12) of inserting the error of the transmission period of the beacon frame into the beacon frame (Fig. 3 (a)) and the structure of the beacon frame according to the present invention Fig. 3 (b).

First, the structure of a general beacon frame according to the Zigbee standard shown in (a) of FIG. 3 will be briefly described as follows. As shown in FIG. 3A, the beacon frame includes a MAC header 100, a MAC payload 200, and a MAC footer (MFR) 300. It consists of three parts.

The MAC header 100 includes a frame control field 110 including a beacon identifier, a sequence number field indicating a sequence number for the current frame, and an addressing field including a source address. field).

The MAC payload 200 provides a superframe specification field 210 that defines a logical timeslot for time management of transmission and reception, and provides a guaranteed time slot to a specific network device. A guaranteed time slot (GTS) field 220 including information for a field, a pending address field 230 including an address of a network device to be transmitted when data to be transmitted to the network device is generated, and a beacon payload ( Beaconpayload) 240.

The MAC footer (MFR) 300 includes a frame check sum (FCS) for error checking of a transmitted frame.

In the present invention, as shown in Figure 3 (b), in addition to the MAC payload 200 of the beacon frame additional field (Xtal error field) 250 containing information on the error of the transmission period of the beacon frame Define it and insert it. As such, the error of the transmission period of the beacon frame determined by the network coordinator is defined as an additional field in the MAC payload 200 of the beacon frame and transmitted to the network device, so that the network device can accurately determine the error of the transmission period of the beacon frame. Will be.

1 and 2, the network coordinator 11 transmits a beacon frame including an error in the transmission period of the beacon frame (S13), and the network device receives the beacon frame (S21).

Subsequently, the network device 12 that receives the beacon frame including the transmission period error of the beacon frame stores the received beacon frame in the internal memory (S22), and the MAC payload of the stored beacon frame (FIG. 3 (b)). The time point at which the receiver is turned on is determined by reading a field (250 of FIG. 3B) which defines an error of a transmission period of the beacon frame inserted in the reference numeral 200).

As described above, the present invention transmits the information about the transmission period error of the beacon frame determined by the network coordinator 11 to the network device 12 so that the network device 12 wakes up to receive a later beacon frame. Effectively determine the point of view. As a result, power consumption can be reduced as compared with the prior art, which waits for a beacon frame reception by waking up in advance without any information on the transmission period error of the beacon frame. This feature is very effective when applied to a sensor network where low power is absolutely required.

As described above, according to the present invention, by transmitting the information about the error of the beacon frame transmission period determined by the network coordinator to the network device to enable the network device to wake up at an appropriate time in accordance with the error of the beacon frame transmission period Therefore, it is possible to reduce unnecessary power consumption in a Zigbee system requiring low power characteristics.

Claims (5)

Determining an error in a transmission period of a beacon frame in the network coordinator; Inserting an error of a transmission period of the determined beacon frame into the beacon frame; The network coordinator transmitting the beacon frame and the network device receiving the transmitted beacon frame; Storing the received beacon frame at the network device; And Determining a time point at which the receiver is turned on according to an error of a transmission period of a beacon frame inserted into the received beacon frame in the network device; Wake-up method of a network device in a Zigbee system comprising a. The method of claim 1, wherein determining the error of the transmission period of the beacon frame, And determining an error of a transmission period of the beacon frame according to a reference frequency error of the crystal oscillator included in the network coordinator. The method of claim 2, wherein the determining of the error of the transmission period of the beacon frame, The error of the transmission period of the beacon frame is determined as a multiple of the unit backoff period, wherein the multiple of the unit backoff period is larger than the actual time error of the beacon frame transmission period due to the reference frequency error of the crystal oscillator included in the network coordinator. Wake-up method of a network device in a Zigbee system, characterized in that having a. The method of claim 1, wherein the step of inserting into the beacon frame, And defining an error in a transmission period of the beacon frame as an arbitrary field in the beacon frame. The method of claim 4, wherein the inserting into the beacon frame comprises: Wakeup method of a network device in a Zigbee system, characterized in that for defining the error in the transmission period of the beacon frame to any field in the MAC payload included in the beacon frame.

Images