KR20080043049A - Superframe structure based on ieee802.15.4 and data transmission method using therefor - Google Patents

Abstract

A structure for an IEEE 802.15.4-based superframe and a data communication method using the same are provided to shorten an average delay time for data which are generated at an inactive interval. An IEEE 802.15.4-based superframe comprises a beacon frame(B), the first active interval(A1), an inactive interval(I), and the second active interval(A2). At the first and second active intervals, data can be transmitted. Data cannot be transmitted at the inactive interval. The sum of the beacon frame and the first active period is equal to the value of the second active interval. In this case, the value of the second active interval "SD" is "basic superframe length x 2^SO(Superframe Order)/2".

Description

IEEE 802.15.4 based superframe structure and data communication method using the same {SUPERFRAME STRUCTURE BASED ON IEEE802.15.4 AND DATA TRANSMISSION METHOD USING THEREFOR}

1 is a conventional superframe structure diagram.

2 is a block diagram of a general star topology.

3 is a data communication timing diagram used in a conventional superframe structure.

4 is a superframe structure diagram according to the present invention.

5 is a data communication timing diagram using a superframe structure according to an embodiment of the present invention.

The present invention relates to a medium access control (MAC) layer of IEEE 802.15.4 based on a MAC layer and a physical layer in Zigbee, a type of wireless communication network (WPAN), and more specifically, data communication between devices. The present invention relates to a superframe structure based on IEEE 802.15.4 and a data communication method using the same in order to reduce delay occurring during a transmission.

ZigBee is one of the IEEE 802.15.4 standards supporting near field communication. It is a technology for near field communication and ubiquitous computing of about 10 to 20 meters in wireless networking fields such as home and office. This Zigbee is a concept of a mobile phone or a wireless LAN, and has a concept of communicating a small amount of information instead of minimizing power consumption.

ZigBee is being used in short-range communications markets such as intelligent home networks and buildings, and in industrial equipment automation, logistics, environmental monitoring, human interfaces, telematics and military. In particular, since Zigbee has been miniaturized and consumes less power and is cheaper, it has been in the spotlight as a ubiquitous construction solution such as a home network.

Meanwhile, IEEE 802.15.4 is a TG4 in IEEE 802.15, and is a standard activity for a low transmission rate wireless device for the purpose of low power and low cost. When using such a wireless personal area network (WPAN) device, As a result, frequency bands without license restrictions can be used. Applications of such wireless personal area network devices are expanding to sensors, actuators, interactive toys, remote controls, industrial networks, home automation, and the like.

The standards body, IEEE 802.15.4, is intended to define the physical and MAC layers of low-power wireless devices that can last from months to years of battery life. Currently, the discussion of MAC enhancement and alternative PHY of the IEEE 802.15.4 LR-WPAN system in the IEEE 802.15.4a is ongoing.

The following are the main functions defined as a result of standard activities.

Data rates of 250 kbps, 40 kbps and 20 kbps

Star topology, peer to peer possible

255 devices per network

CSMA-CA channel access mechanism

Optional Guaranteed Time Slot

Fully handshaked protocol for transfer reliability

Low power (battery life multi-month to nearly infinite)

Dual PHY (2.4GHz and 868/915 MHz)

Extremely low duty-cycle (<0.1%)

Range: 10m nominal (1-100m based on settings)

Location Aware: Yes, but optional

On the other hand, in ZigBee, each device performs data communication using the concept of time called superframe.

As shown in FIG. 1, which is each superframe, the frame is divided into a beacon frame B, an active section A, and an inactive section I.

Beacon frame (B) is a PAN coordinator that manages the network transmits to all devices to synchronize with the devices, and determines the structure of the superframe, SO (Superframe Order), BO (Beacon order) Contains a value. For reference, SO and BO are values determined by the PAN coordinator based on the status of the network. For example, if there is a lot of data to be sent, SO and BO should be set as large values, and in case of real-time traffic, BO should be set as small values.

The PAN coordinator may also pass the number of devices to which data to be received is transmitted through a pending list.

As a result, after receiving the beacon frame, the devices determine the beacon interval BI by the BO value and the active period SD by the SO value. For reference, BI is the length until the next beacon is transmitted, SD is the length from the start of the beacon frame to the end of the active interval. Meanwhile, as the BI and the SD are determined, an inactive section is automatically determined.

SO is greater than or equal to "0" and less than or equal to "BO". Further, BO is less than or equal to 14 (0 ≦ SO ≦ BO ≦ 14).

If the ID is included in the pending list, the device receives the data through the data request. That is, in the star topology as shown in FIG. 2, data generated from all devices are delivered to the PAN coordinator and then to the destination device.

In the star topology as shown in FIG. 2, there are the following problems.

The structure of the conventional superframe repeats the beacon frame (B), the active section (A), the inactive section (I), as shown in FIG.

Looking at the data delivery process, the data generated at point a of device A of FIG. The beacon message is sent, and the device B transmits a data request message in a next active period to transmit predetermined data.

However, as shown in FIG. 3, when data is generated at point b, which is an inactive section of the superframe F3, the device waits for the active section of the superframe F4 where all devices operate, and then delivers the data to the PAN coordinator. Likewise, the target device B is delivered to the active section of the superframe F5.

That is, the data generated in the inactive section is delayed more than the data generated in the active section and transferred to the target device B.

The present invention has been made in view of the above circumstances, and aims to reduce the delay time associated with the transfer of data generated in an inactive period to a destination device.

In addition, another object of the present invention is to provide a superframe structure for reducing the delay time associated with the transmission of data generated in the inactive period to the destination device.

In order to achieve the above object, IEEE 802.15.4 based superframe structure according to the present invention, IEEE 802.15.4 based superframe structure having a star topology, the beacon frame; A first active section capable of transmitting data; Inactive sections where data cannot be transmitted; And a second active section capable of transmitting data in sequence.

In order to achieve the above object, a data communication method using the IEEE 802.15.4-based superframe structure according to the present invention, a beacon frame, a first active period that can transmit data, an inactive period that can not transmit data In the communication method of the IEEE 802.15.4-based superframe structure having a second active interval for transmitting data, a) When data is generated in the first active interval in the originating device, Transmitting the data to a PAN coordinator; b) when the originating device generates data in the inactive section or the second active section, transmitting the data to the PAN coordinator in the second active section; c) transmitting, by the PAN coordinator, the received data to the target device in the first active period of the next superframe.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The environment to which the present invention is applied is as follows.

The topology applies to star topologies operating on IEEE 802.15.4. As shown in FIG. 2, in the star topology, data generated in all devices is delivered to the central PAN coordinator, and is transferred to the destination device by the PAN coordinator.

Beacons are applied to the beacon-enable network environment in IEEE 802.15.4. A beacon-enable network is a method in which a PAN coordinator periodically sends beacon messages to devices.

4 is a diagram illustrating a structure of a superframe applied to the present invention.

As shown in FIG. 4, the superframe according to the present invention includes a beacon section B, a first active section A1, an inactive section I, and a second active section A2.

The sum of the beacon section B and the first active section A1 is "SD", and the second active section A2 is also "SD". SD is the same as [Equation 1].

In addition, the entire superframe period BI is shown in [Equation 2].

As shown in FIG. 5, when a data occurs in the first active period A1 of the superframe F1 in the device A, the a data is PAN in the first active period A1 of the superframe F1. It is delivered to the coordinator to the destination device B in the superframe (F2).

On the other hand, when b data occurs in the inactive section B of the superframe F3 in the device A, the b data is transferred to the PAN coordinator in the second active section A2 of the superframe F3, and the superframe The first active section A1 of F4 is transmitted to the target device B.

In the case of using the superframe having the structure as shown in FIG. 1, when data is generated in the inactive section I of the superframe F3 in the device A as shown in FIG. 3, the data is displayed in the active section A of the superframe F5. Is sent to the target device B. Therefore, the target device B can receive the data transmitted from the device A after the one-cycle superframe has elapsed.

However, in the present invention using the superframe having the structure as shown in FIG. 4, when data is generated in the inactive section I of the superframe F3 in the device A, the data is displayed in the active section A of the superframe F4. Is sent to the target device B.

Thus, the target device B can receive the data transmitted from the device A without delay.

In particular, as shown in FIG. 5, in the present invention, all data generated in the first and second active sections A1 and A2 of the superframe F3 or data generated in the inactive section I are all superframes F4. It can be transmitted to the target device B in the active section (A1) of.

6A is a graph of average delay theory in a conventional superframe structure, and FIG. 6B is a graph of average delay theory in a superframe structure according to the present invention.

The X axis of the average delay theory graph is the generation time (superframe), and the Y axis is the delay time.

According to FIG. 6A, data generated under 1 / 2s (Superframe), which is an active section of a superframe, arrives at a destination within one superframe, but data occurring at 1 / 2s or more, which is an inactive section, reaches a destination after a maximum of 1.5s. I can see that I get to

On the other hand, according to FIG. 6B according to the present invention, it can be seen that data generated in all sections arrive at a destination in one superframe. That is, when the data success rate is 1, the average delay in the conventional superframe structure is 1s, and 1 / 2s in the superframe structure according to the present invention.

As described above, according to the superframe structure according to the present invention, the average delay time according to the conventional superframe structure can be reduced to 1/2.

As described above, according to the IEEE 802.15.4 superframe structure and the data communication method using the same according to an embodiment of the present invention, there is an effect that the average delay time for the data generated in the inactive interval can be reduced.

On the other hand, the present invention is not limited to the above-described embodiment, but can be modified and modified within the scope not departing from the gist of the present invention, such modifications and changes should be regarded as belonging to the following claims. will be.

Claims (9)

In the IEEE 802.15.4 based superframe structure having a star topology, Beacon frame; A first active period capable of transmitting data; An inactive period in which data cannot be transmitted; And IEEE 802.15.4 based superframe structure, characterized in that the second active interval for transmitting data is provided in sequence. The method of claim 1, wherein the sum of the beacon frame and the first active period is IEEE 802.15.4 based superframe structure, characterized in that the same as the value of the second active period. The method of claim 2, wherein the second active period is

IEEE 802.15.4 based superframe structure, characterized in that. However, the SO (Superframe Order) is a value determined by the PAN coordinator based on the status of the network. The method of claim 1 or 3, wherein the inactive interval is Super frame cycle

The superframe structure based on IEEE 802.15.4, wherein the beacon frame value, the first active interval value, and the second active interval value are excluded. However, the BO (Beacon Order) is a value determined by the PAN coordinator to view the state of the network. In a communication method of a superframe structure based on IEEE 802.15.4 having a beacon frame, a first active period for transmitting data, an inactive period for transmitting data, and a second active period for transmitting data, a) transmitting data to the PAN coordinator in the first active section when data is generated in the first active section in the originating device; b) when the originating device generates data in the inactive section or the second active section, transmitting the data to the PAN coordinator in the second active section; and c) transmitting, by the PAN coordinator, the received data to a target device in a first active period of a next superframe. The method of claim 5, wherein The originating device, the PAN coordinator, and the destination device is a communication method using a superframe based on IEEE 802.15.4, characterized in that configured in a star topology. The method of claim 5, wherein the sum of the beacon frame and the first active period is IEEE 802.15.4 based superframe structure, characterized in that the same as the value of the second active period. The method of claim 7, wherein the second active period is

IEEE 802.15.4 based superframe structure, characterized in that. However, the SO (Superframe Order) is a value determined by the PAN coordinator based on the status of the network. The method of claim 5 or 8, wherein the inactive interval is Super frame cycle

The superframe structure based on IEEE 802.15.4, wherein the beacon frame value, the first active interval value, and the second active interval value are excluded. However, the BO (Beacon Order) is a value determined by the PAN coordinator to view the state of the network.

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