KR101438210B1 - Method and apparatus for adjusting a length of super frame - Google Patents

Abstract

The present invention relates to an access control method for data transmission and reception of an apparatus in a wireless network. A method for adjusting the length of a superframe according to the present invention comprises the following steps: initializing parameters for adjustment of the length of the superframe; changing a beacon order (BO) defining the order of beacons among the parameters by checking a rate that packets are accumulated in a queue during the superframe; determining the beacon order by comparing the changed beacon order with a predetermined threshold; and calculating a beacon interval using the beacon order. According to the present invention, it is possible to reduce probability that a mobile device on a ZigBee network may be in an active mode by adjusting the length of the superframe according to probability of occurrence of data all over the ZigBee network.

Description

 BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for adjusting a length of a superframe,

 The present invention relates to an access control method for data transmission and reception of a device in a wireless network, and more particularly, to a super frame in an IEEE 802.15.4 based wireless sensor network in a beacon-enabled mode.

The wireless sensor network (WSN) is one of the key technologies in the ubiquitous era, and has attracted more attention with the rapid development of wireless communication and network theory. Wireless sensor networks can be used in industrial automation, home automation, military, agricultural, health care and many other areas. The design of wireless sensor network systems is very deeply related to specific application areas. For industrial applications, wireless sensor network systems must be characterized by real - time transmission, low power consumption, high security, scalability and robustness.

IEEE 802.15.4 (Low-Rate Wireless Personal Area Networks) has become the standard for the physical layer and link layer of sensor networks, and ZigBee using them has released various applications in many fields. In addition, IEEE 802.15.4 proposes a wireless connection in which a physical (PHY) layer and a medium access control (MAC) layer are defined.

After IEEE 802.15.4 was released, many researchers have proposed many improvements and as a result, the performance of the specification has improved. For example, a performance analysis of the GTS allocation mechanism has been introduced and a traffic scheduling technique has been proposed to improve the energy efficiency of the network. In addition, implicit GTS allocation mechanisms have also been proposed to improve GTS bandwidth utilization, and message scheduling techniques have been introduced to improve scalability and real-time performance of industrial applications. In addition, an adaptive GTS allocation scheme has been proposed to improve delay and fairness. However, despite these efforts, IEEE 802.15.4 still has weaknesses in traffic scheduling due to inherent constraints of the specification.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the prior art, and it is an object of the present invention to solve the problem of maintaining the activated state in the mobile device of the Zigbee network, And a method for reducing energy consumption of the apparatus.

According to another aspect of the present invention, there is provided a method of adjusting a superframe length of a wireless network, the method comprising: initializing a variable for controlling a superframe length; Changing a beacon order (BO) defining a sequence of beacons among the variables by checking a rate at which packets are accumulated in a queue during a superframe; Comparing the changed beacon order with a predetermined threshold to determine a beacon order; And calculating the beacon interval using the beacon sequence.

Preferably, the superframe length control method calculates the length of the inactivity period using the calculated beacon interval.

The changing step may increase the number of packets to be queued in the queue if the rate of accumulation of the packets is low.

Preferably, the modifying step initializes the beacon order variable when the rate of accumulating the packets in the queue is high.

The superframe length adjusting method may further include calculating a length of the inactivation interval using the calculated beacon interval and the length of the active interval of the initialized variables.

Preferably, the initializing step initializes the length of the active period among the variables to a basic superframe length defined in a predetermined standard.

The length of the inactivation interval may be calculated as a difference between the beacon interval and the length of the activation interval.

Wherein the superframe includes a listening interval for confirming arrival of a packet during the superframe; An activation period in which at least one device connected to the wireless network can transmit and receive data; And an inactivity period in which the device connected to the wireless network sleeps.

 According to the present invention, the probability of the activation mode of the mobile device on the ZigBee network can be reduced by adjusting the length of the superframe according to the probability that data is generated in the entire Zigbee network.

1 is a diagram illustrating a superframe structure that can be used in a beacon mode according to the IEEE 802.15.4 standard.
FIG. 2 is a flowchart illustrating a method of adjusting a superframe length of a wireless network according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a detailed flowchart illustrating a method of adjusting a superframe length of a wireless network according to an exemplary embodiment of the present invention.
4 is a diagram illustrating a superframe structure of a wireless network according to an embodiment of the present invention.
5 is a diagram illustrating an apparatus for adjusting a superframe length of a wireless network according to an embodiment of the present invention.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. It is also to be understood that all conditional terms and examples recited in this specification are, in principle, expressly intended for the purpose of enabling the inventive concept to be understood, and are not intended to be limiting as to such specifically recited embodiments and conditions .

It is also to be understood that the detailed description, as well as the principles, aspects and embodiments of the invention, as well as specific embodiments thereof, are intended to cover structural and functional equivalents thereof. It is also to be understood that such equivalents include all elements contemplated to perform the same or similar functions irrespective of the currently known equivalents as well as the equivalents to be developed in the future.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: . In the following description, a detailed description of known technologies related to the present invention will be omitted when it is determined that the gist of the present invention may be unnecessarily blurred. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The IEEE 802.15.4 standard defining the MAC layer is briefly introduced and a structural problem that may arise in an environment in which embodiments are implemented. This standard supports two modes: beacon-enabled mode and non-beacon-enabled mode. Of these, embodiments of the present invention to be described below relate only to a beacon mode, so only a beacon mode is introduced here.

1 is a diagram illustrating a superframe structure that can be used in a beacon mode according to the IEEE 802.15.4 standard. A superframe is divided into an active portion where one device can transmit and receive data and an inactive portion where all devices sleep. The length of an active part called a superframe duration (SD) depends on the superframe order (SO) according to the following equation (1).

[Equation 1]

Here, the variable aBaseSuperframeDuration in Equation (1) is one of the constants defined in the IEEE 802.15.4 standard and has 960 symbol values. The superframe sequence SO is one of the parameters defined in the IEEE 802.15.4 standard, and has an integer value between 0 and 14.

In the beacon transmission period, the network coordinator includes network information and broadcasts beacons used by the end device to connect and synchronize with the network. The intervals between two consecutive beacons are determined by a beacon order (BO), which is a parameter according to the following equation (2), and these intervals indicating the length of one super frame are referred to as a beacon interval (BI) .

&Quot; (2) "

In beacon mode, the maximum allowed value of the beacon sequence BO is 14, and the minimum value is zero. Also, the superframe order SO should not be greater than the beacon order BO.

Now, the environment and situation in which the embodiments of the present invention are utilized will be further simplified as follows. Suppose a network that uses a star topology in which there is one PAN coordinator to collect data and a number of end devices to sense data. The method of adjusting the superframe length according to the present embodiment is performed by the PAN coordinator for collecting data, and detailed steps of the superframe length adjustment are shown in FIG.

FIG. 2 is a flowchart illustrating a method of adjusting a superframe length of a wireless network according to an exemplary embodiment of the present invention. Referring to FIG. 2, the superframe length control method according to the present embodiment includes variable initializing step S100, beacon sequence changing step S200, beacon sequencing step S300, and beacon interval calculating step S400 .

The variable initialization step (S100) initializes a variable for controlling the superframe length.

In this embodiment, variables for controlling the superframe length include an active period (AP), a basic super frame length (T _min = aBaseSuperframeDuration), and a beacon order (BO).

The active period is a part where a device in the wireless network can transmit and receive data. The basic superframe length is one of constants defined in the IEEE 802.15.4 standard and has 960 symbol values. The beacon order is given by the above-described equation (2) as the interval between two consecutive beacons.

Referring to FIG. 3, the variable initializing step S100 includes an active period length setting step S110 and a beacon sequence initializing step S120.

The active period length setting step S110 sets the active period length to the basic super frame length. That is, the initialization step S100 initializes the length of the active period of the variable to the basic superframe length defined in the predetermined standard, which can be expressed by Equation (3).

&Quot; (3) "

Further, beacon sequence initialization step (S120) initializes the beacon sequence. Can be expressed as Equation (4).

&Quot; (4) "

BO = 1

The beacon sequence changing step S200 checks the queue status during the superframe, and changes the beacon order (BO), which defines the sequence of beches among the variables, when the queue status is lower than a predetermined reference value (threshold value). As another embodiment, the beacon order (BO) for defining the order of beacons among the variables may be changed by confirming whether or not a packet has arrived during a superframe.

Referring to FIG. 3, the beacon sequence changing step S200 includes a queue status checking step S210 and a beacon sequence increasing step S220.

The queue status checking step (S210) checks the rate at which packets are accumulated in the queue during each superframe. As a result, if the rate at which packets are accumulated in the queue is greater than a predetermined reference value, the beacon sequencing variable is initialized. That is, the beacon sequence initializing step (S120) of the variable initializing step (S100) is branched to initialize the beacon order to zero.

When the rate at which the packets are accumulated in the queue is smaller than the predetermined reference value, in the present embodiment, the beacon sequence changing step S200 increases the beacon sequence variable, and increases the beacon sequence by one step through the beacon sequence increasing step S220 .

The beacon order determination step S300 compares the changed beacon order with a predetermined threshold to determine the beacon order. Referring to FIG. 3, the beacon order determination step S300 includes a threshold comparison step S310 and a beacon order setting step S320.

In the threshold comparison step S310, the BO is one of the parameters defined in the IEEE 802.15.4 standard, and has an integer value ranging from 0 to 14 as the maximum tongue value, Compare with threshold 14.

The beacon order setting step S320 sets the beacon order to 14 when the beacon order increased from the threshold value 14 is large.

If the threshold value is less than or equal to 14, the increased beacon sequence value is set as it is.

Next, the beacon interval calculating step (S400) calculates the beacon interval using the beacon sequence.

In this embodiment, the beacon interval can be expressed by Equation (5).

&Quot; (5) "

In addition, the superframe length control method further includes a step S500 of calculating the length of the inactivation interval using the calculated beacon interval and the length of the activation interval among the initialized parameters. That is, the length of the inactivation interval is calculated as a difference between the beacon interval and the length of the active interval, and the calculated beacon interval (BI) can be expressed by Equation (6).

&Quot; (6) "

Through the above process, the structure of the super frame according to the present embodiment can be represented as shown in FIG.

Referring to FIG. 4, the superframe according to the present exemplary embodiment includes a listening interval for checking whether a packet arrives during a superframe, an active interval during which at least one device connected to the wireless network can transmit / receive data, And a deactivation period in which a device connected to the wireless network sleeps.

The second beacon frame is BO = 2, SO = 0, the third beacon frame is BO = 3, SO = 0, and the n-th beacon frame is BO = n, And SO = 0.

That is, in the super frame according to the present embodiment, the PAN coordinator for collecting data adjusts the superframe size according to the probability that data is generated in the entire Zigbee network, thereby reducing the probability that the mobile device on the ZigBee network becomes the active mode, Energy consumption can be reduced.

Hereinafter, an apparatus for performing a method of adjusting a superframe length of a wireless network according to the present embodiment will be described with reference to FIG.

The apparatus for controlling superframe length of a wireless network according to the present embodiment includes a variable initializing unit 100, a beacon sequence changing unit 200, a beacon sequence determining unit 300, a beacon interval calculating unit 400, (500).

The variable initialization unit 100 initializes a variable for controlling the superframe length.

The beacon reordering unit 200 changes the beacon order (BO) that defines the order of beacons among the variables by confirming the rate at which packets are accumulated in the queue during the superframe.

The beacon order determination unit 300 determines the beacon order by comparing the changed beacon order with a predetermined threshold value.

The beacon interval calculating unit 400 calculates the beacon interval using the beacon sequence.

The inactivity period length calculating unit 500 calculates the inactivity period length using the calculated beacon interval and the length of the active period among the initialized variables.

The superframe length adjusting device may be implemented as an internal module of the PAN coordinator, and each configuration performs corresponding steps of the superframe length adjusting method described above, and a detailed description thereof will be omitted.

Meanwhile, the super frame length adjustment method of the wireless network of the present invention can be implemented by a computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like. Computer-readable code in a distributed fashion can be stored and executed. In addition, functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers skilled in the art to which the present invention belongs.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be.

Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (15)

Initializing a variable for controlling a superframe length;
A beacon order (BO) variable for defining a sequence of beacons among the variables is incremented when a rate at which packets are accumulated in a queue during a superframe is lower than a predetermined criterion And initializing the beacon sequence variable to change a beacon sequence if the rate of accumulation of the packet in the queue is higher than a predetermined criterion;
Comparing the changed beacon order with a predetermined threshold to determine a beacon order; And
And calculating a beacon interval using the beacon sequence. The method according to claim 1,
Wherein the superframe length adjustment method calculates the length of the inactivity interval using the calculated beacon interval. delete delete 2. The superframe length adjusting method according to claim 1,
And calculating the length of the inactivation period using the calculated beacon interval and the length of the active period of the initialized parameters. 6. The method of claim 5,
Wherein the initializing step initializes the length of the active period among the variables to a default super frame length defined in a predetermined standard. The method according to claim 6,
Wherein the length of the inactive section is calculated as a difference between the beacon interval and the length of the active section. The method of claim 1,
The superframe
A listening interval for confirming arrival of a packet during the super frame;
An activation period in which at least one device connected to the wireless network can transmit and receive data; And
Wherein the wireless network includes an inactive period in which a device connected to the wireless network sleeps. A variable initialization unit for initializing a variable for controlling the superframe length;
A beacon order (BO) variable for defining the order of beacons among the variables when a ratio of accumulating the packets in the queue is lower than a predetermined criterion, A beacon sequence changing unit for initializing the beacon sequence variable when a ratio of the packets accumulated in the queue is higher than a predetermined reference;
A beacon sequence determining unit for comparing the changed beacon sequence with a predetermined threshold to determine a beacon sequence;
A beacon interval calculating unit for calculating a beacon interval using the beacon sequence; And
And a deactivation period length calculator for calculating a deactivation period length using the calculated beacon interval and the length of the active period of the initialized parameters. delete delete delete 10. The method of claim 9,
Wherein the variable initializing unit initializes the length of the active period among the variables to a basic super frame length defined in a predetermined standard. 10. The method of claim 9,
Wherein the length of the inactive section is calculated as a difference between the beacon interval and the length of the active section. Initializing a variable for controlling a superframe length;
A beacon order (BO) variable for defining a sequence of beacons among the variables is incremented when a rate at which packets are accumulated in a queue during a superframe is lower than a predetermined criterion And initializing the beacon sequence variable to change the beacon order if the ratio of the packets accumulated in the queue is higher than a predetermined criterion;
Comparing the changed beacon order with a predetermined threshold to determine a beacon order;
And calculating the beacon interval using the beacon sequence on the computer.

Images