KR20120117304A - A node and a method for waking up the node - Google Patents

Abstract

PURPOSE: A node and wake-up method thereof are provided to reduce the number of unnecessary operations for enabling a node to receive beacon frames. CONSTITUTION: An ACK(ACKnowledgement) frame reception unit(21) receives an ACK frame. The ACK frame includes information for waking up a node. A beacon frame reception unit(23) receives a beacon frame. A control unit(22) receives the ACK frame. The control unit wakes up the beacon frame reception unit. The node includes signal period information. [Reference numerals] (21) ACK frame reception unit; (22) Control unit; (23) Beacon frame reception unit; (24) Data frame transmission unit; (25) ACK frame transmission unit; (26) Beacon frame transmission unit; (27) Data frame reception unit; (AA) Coordinator; (BB) Node

Description

A node and a method for waking up the node}

One embodiment of the present invention relates to a wireless communication network, and more particularly, to a data communication method of a wireless human area network.

In recent years, wireless communication technologies have evolved to support all types of media and data services. In accordance with this trend, a portable wireless biosignal monitoring system has been developed. The existing technology that can be applied to such a system is a local area wireless personal network (WPAN). There are technologies such as Bluetooth and Zigbee in the WPAN field, and technologies such as Bluetooth and Zigbee are well-proven systems. However, because these systems target a more flexible network environment and use a longer range of communication than medical systems, they are not optimized for biosignal monitoring systems. It does not satisfy energy efficiency. Accordingly, a low power and low cost wireless body area network (WBAN) has attracted attention as a technology for monitoring a patient's biological signal in real time. As WBAN technology became important, the draft TG6 was released in May 2010, and standardization is underway.

In such a wireless body area network, a node must periodically wake up to receive a beacon frame transmitted by the coordinator. However, since the fields of the beacon frame are data about the network structure, there is no need for the node to keep wake up to receive the beacon frame unless there is a change in the network. However, if it does not receive the beacon frame, it is a problem that the loss of energy because the network must be disconnected and re-association every time the network changes. Accordingly, an object of the present invention is to propose a node wake-up method for solving such a problem.

Wake-up method of a node according to an embodiment of the present invention for achieving the above object relates to a wireless human area network. The node wake-up method includes receiving an ACK frame including information for a node to wake up the node, and waking up the node receiving the ACK frame. The ACK frame includes a MAC header field, an acknowledgment information field of a received data frame, and a node wakeup information field, wherein the node wakeup information field has a size of 1 byte, and indicates the node. The information to wake up is characterized in that it includes signal cycle information that the node should wake up.

In addition, by assigning a 1-bit field to the Mac header, the node is woken up when the 1-bit field of the ACK frame received by the node has a value of 1.

According to another aspect of the present invention, a node receives an ACK frame including information for waking up the node, the node receiving the ACK frame wakes up, and the wakeup node is a beacon frame Receiving a, there is provided a data communication method comprising a.

According to another aspect of the present invention, a node includes an ACK frame receiving unit for receiving an ACK frame including information for waking up a node, a beacon frame receiving unit for receiving a beacon frame, and the beacon frame receiving unit for receiving the ACK frame. A coordinator according to the present invention includes an ACK frame transmitter for transmitting an ACK frame including information for waking up a node and a beacon frame transmitter for transmitting a beacon frame.

According to the node wake-up method according to an embodiment of the present invention, when the network does not change, the node does not need to wake up unnecessarily to receive a beacon frame, thereby reducing power consumption.

1 illustrates a configuration of a general wireless human body area network according to an embodiment of the present invention.
2 illustrates a node and coordinator according to an embodiment of the present invention.
3 is a flowchart illustrating a node wake-up method according to an embodiment of the present invention.
4 shows a structure of an ACK frame according to an embodiment of the present invention.
FIG. 5 illustrates the structure of a MAC header field and an frame control field included in a MAC header field of an ACK frame according to an embodiment of the present invention.
6 shows a structure of a beacon frame according to an embodiment of the present invention.
7 illustrates a node wakeup method according to an embodiment of the present invention in comparison with a general node wakeup method.
8 illustrates a node wakeup method for a plurality of nodes according to an embodiment of the present invention.
9 is a graph showing a power consumption of the node according to the beacon frame reception period according to an embodiment of the present invention.

The embodiments may be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Rather, the above aspects make the embodiments more thorough and complete, and fully convey the scope of the embodiments to those skilled in the art.

In addition, throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, without excluding the other components unless otherwise stated.

In addition, throughout the specification, "signal period" means one period in which a node receives a beacon frame and an ACK frame from a coordinator and the node transmits a data frame to the coordinator. The term "beacon frame reception period" means a period in which a node receives a beacon frame from the coordinator within the signal period.

One embodiment of the present invention relates to a node wake-up method, wherein a node receives a ACK frame including information for waking up the node.

Hereinafter, a node wake up method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a configuration of a wireless body area network (WBAN) according to an embodiment of the present invention.

As shown in FIG. 1, the WBAN includes a coordinator and a plurality of nodes that communicate with the coordinator. The coordinator periodically transmits a beacon frame to nodes and performs functions such as network configuration, node management, node information storage, and message routing between nodes. Nodes receiving this beacon frame join the network by an association process.

The nodes synchronize synchronization with a beacon frame transmitted by the coordinator, periodically transmit a data frame to the coordinator, and the coordinator receiving the data frame transmits information indicating that the node has normally received through the ACK frame. On the other hand, the nodes reduce the energy consumption by maintaining a sleep (sleep) state in the period of no frame transmission and reception.

 2 illustrates a node and coordinator according to an embodiment of the present invention.

As shown in FIG. 2, a node according to an embodiment of the present invention includes an ACK frame receiver 21, a beacon frame receiver 23, a controller 22, and a data frame transmitter 24. For example, it may be an electrocardiogram (ECG) or an electromyogram (EMG). Hereinafter, an embodiment of the node will be described using an electrocardiogram. The ACK frame receiving unit 21 receives the ACK frame from the coordinator and delivers it to the control unit 22. The control unit 22 wakes up the beacon frame receiving unit 23 according to the received ACK frame information. Accordingly, the beacon frame receiver 23 wakes up to receive the beacon frame from the coordinator. The coordinator includes an ACK frame transmitter 25, a beacon frame transmitter 26, and a data frame receiver 27.

3 illustrates a node wake-up method according to an embodiment of the present invention.

As shown in FIG. 3, in a node wake-up method according to an embodiment of the present invention, a node maintains a sleep state (S301), a node receives an ACK frame (S302), and a node The beacon frame receiving unit wakes up (S303), the beacon frame receiving unit of the node receives a beacon frame from the coordinator (S304), the node transmits a data frame to the coordinator (S305).

As described above, step S301 in which the node is in a sleep state indicates that the node is in a sleep state in order to reduce energy consumption when there is no frame transmission and reception. The node receives the ACK frame from the coordinator and wakes up during the beacon frame reception period. Hereinafter, the structure of the ACK frame will be described first. The node wake-up method according to an embodiment of the present invention will be described below. do.

4 shows a structure of an ACK frame according to an embodiment of the present invention.

As shown in FIG. 4, an ACK frame according to an embodiment of the present invention includes a MAC header field, an acknowledgment information field (FCS) of a received data frame, and a node wakeup information field (MAC Frame Body). It includes. The node wakeup information field includes information on which beacon frame reception period the node should wake up. The node wakeup information field may have a size of 1 byte, for example.

5 illustrates the structure of the MAC header field and the frame control field included in the MAC header field of the ACK frame according to an embodiment of the present invention.

As shown in FIG. 5, the MAC header field 51 of the ACK frame includes a frame control field 52, and the frame control field 52 is used for 'Selective Beacon Listening'. Contains a 1-bit field.

Referring to the fields of the frame control field 52, the ACK Policy field is a field for indicating an acknowledgment request of the current frame. The Security Level field represents the security level of the current frame. The TK index field indicates a group temporary key used for security of the current frame. The relay field is a field for frame relay of a node in a star network. The Frame subtype field indicates a subtype of the current frame. The Frame type field indicates the type of the current frame. Subtypes include Beacon, Reserved, Command, I-Ack, Wakeup, and Emergency. Types include Control, Management, and Data.

The node wake-up method according to an embodiment of the present invention may allocate the 1-bit field so that the node wakes up only when the 1-bit field of the ACK frame received by the node has a value of 1. If the value of the 1-bit field is 0, the node wakes up every beacon frame receiving period regardless of whether the ACK frame is received. That is, by allocating the 1-bit field, it is compatible with the existing node wakeup method in which the node wakes up every beacon frame reception period.

Subsequently, a step (S302) in which the node receives the ACK frame and a step (S303) in which the beacon frame receiver of the node wakes up will be described in detail.

Referring back to FIG. 2, the ACK frame receiving unit 21 of the node receives an ACK frame from the coordinator and transmits the ACK frame to the control unit 22, and the control unit 22 uses node wakeup information included in the ACK frame. Thus, the node wakes up the beacon frame receiving unit 23 according to the beacon frame receiving period in which the node should wake up to receive the beacon frame.

Next, a step (S304) of receiving a beacon frame from the beacon frame receiving unit of the coordinator will be described in detail.

The node receiving the ACK frame from the coordinator wakes up at a predetermined signal period according to the node wakeup information included in the ACK frame, and receives the beacon frame from the coordinator. The structure of the beacon frame is shown in FIG. 6 and will be described below.

6 shows a structure of a beacon frame according to an embodiment of the present invention.

As shown in FIG. 6, the structure of a beacon frame according to an embodiment of the present invention is based on a draft proposed for standardization of WBAN. The beacon frame structure may include, for example, a beacon shifting sequence field, and the beacon shifting sequence field may include state change information of a network including a node and a coordinator. The state change information of the network may be, for example, network connection state information between a node and a coordinator. That is, when a network change occurs while transmitting and receiving a frame while the node and coordinator are synchronized, the coordinator needs to transmit a beacon frame including the changed network information to the node, and the node is configured to transmit the beacon. It must wake up to receive the frame.

Referring to each field of the beacon frame shown in Figure 6, the Sender Address field represents the IEEE MAC address value of the coordinator for transmitting the current beacon frame. The Beacon Period Length field indicates the length of the current beacon frame reception period. The Allocation Slot Length field indicates the length of an allocated slot. The RAP1 start field and the RAP2 start field indicate the number of slots that start the random access phase. The Beacon Shifting Sequence field is a field existing when a beacon frame conversion occurs and indicates a transmission time of a beacon frame in the current beacon frame reception period. The MAC capability field and the PHY capability field are included in a management type frame different from the beacon frame, and the coordinator and the node have different functional needs in order to perform the functions assigned to the fields.

In step S305, the node transmits the data frame to the coordinator. The node periodically transmits the data frame to the coordinator.

7 illustrates a node wakeup method according to an embodiment of the present invention in comparison with a general node wakeup method.

As shown in FIG. 7, when the coordinator needs to transmit a beacon frame including network information changed in the third beacon frame reception period of the node, the coordinator ACKs to the node in the second signal period. After transmitting the frame, the node receives the ACK frame and wakes up in the third beacon frame receiving period. Since the node receives the beacon frame including the changed network information in the third beacon frame receiving period, there is no need to wake up to receive the changed beacon frame transmitted from the fourth signal period. In general, in comparison, a node must wake up to receive a beacon frame from the coordinator at every signal period. That is, in addition to transmitting data frames to the coordinator or receiving an ACK frame from the coordinator, a wakeup state is maintained every beacon frame reception period in order to receive a beacon frame. Therefore, according to the node wake-up method according to an embodiment of the present invention, it is possible to reduce unnecessary energy consumption of the node.

8 illustrates a node wakeup method for a plurality of nodes according to an embodiment of the present invention.

A node according to an embodiment of the present invention periodically transmits a data frame to a coordinator and receives a beacon frame and an ACK frame from the coordinator. By using the periodicity of such a node, it is possible to determine the period in which the node is in the wake-up state in the signal period. Therefore, when there are a plurality of nodes having different wake-up periods, the coordinator transmits an ACK frame to each node in the previous signal period so that all nodes can simultaneously receive a beacon frame including the changed network information.

As shown in FIG. 8, the first node wakes up in all signal cycles, the second node wakes up every 2 signal cycles, the third node wakes up every 3 signal cycles, and the fourth node has 4 signals. It may be in a wake-up state every cycle. For example, when each node needs to receive a beacon frame that the coordinator transmits in the seventh signal period, the coordinator may perform the fourth node in the fourth signal period so that all nodes wake up in the seventh signal period. The ACK frame is transmitted in the fifth signal period as the second node, the sixth signal period as the third node, and the fourth signal period as the fourth node. The first to fourth nodes receiving the ACK frame wake up at the seventh signal period according to the wake-up period information included in the ACK frame to receive the beacon frame.

9 is a graph showing a power consumption of the node according to the beacon frame reception period according to an embodiment of the present invention.

The node transmits a data frame to the coordinator and receives a beacon frame and an ACK frame from the coordinator. The data transmitted by the node was sampled at 12-bit resolution at 1 ms intervals, and the signal period was set to 200 ms. Then, 200 samples were collected and transmitted at once. By the 1V voltage, the node flows in a wake-up state of 3mA when transmitting, 2.7mA when receiving, and 0.07mA when in a sleep state. When transitioning from the sleep state to the wake-up state, a surge current of 4mA flows for 5ms.

Referring to FIG. 7 again, a node according to an embodiment of the present invention is in a wake-up state once to receive a beacon frame for n signal periods, and in case of a general node, to receive a beacon frame for n signal periods. It wakes up n times. By using this, the power consumption of the node and the power consumption of the node in the sleep state by n data frame transmissions, n ACK frame receptions, and 1 beacon frame reception during n signal cycles of the node according to an embodiment of the present invention are calculated. The average power consumption was calculated by dividing by the total time (200ms xn).

In comparison, in the case of a general node, the wake-up state is the same every signal period, so that the power consumption and the sleep state of the node by one data frame transmission, one ACK frame reception, and one beacon frame reception during one signal cycle are the same. The average power consumption was calculated by dividing the power consumption of the node by one signal cycle time (200ms).

수식에서 4.64 ms는 비콘프레임 수신을 위해 노드가 웨이크업 상태를 유지하는 시간이고, 1.6n ms는 ACK프레임 수신을 위해 노드가 웨이크업 상태를 유지하는 시간을 나타낸다. 49.4n ms 는 노드가 데이터프레임을 송신하기 위해 웨이크업 상태를 유지하는 시간을 나타낸다. 5x(n+1)x4는 노드가 n+1번 슬립상태에서 웨이크업 상태로 전환되고 5ms의 시간이 소요되며, 4mA의 전류가 흐르는 것을 의미한다. remind

In the equation, 4.64 ms is a time for a node to wake up for receiving a beacon frame, and 1.6n ms is a time for a node to wake up for receiving an ACK frame. 49.4 n ms represents the time that the node stays awake to transmit the data frame. 5x (n + 1) x4 means that the node transitions to the wakeup state from n + 1 sleep state, takes 5ms, and flows 4mA of current.

수식에서 10 ms 는 1신호주기동안 노드가 2번 슬립상태에서 웨이크업 상태로 전환되는 경우 소요되는 시간을 나타낸다. 1.44 ms 는 ACK프레임 수신을 위해 노드가 웨이크업 상태를 유지하는 시간을 나타낸다.

의 경우 상기 ACK프레임이 노드 웨이크업 정보 필드를 포함하고 있지 않기 때문에

의 경우에 비해 ACK프레임 수신을 위해 노드가 웨이크업 상태를 유지하는 시간이 짧다. remind

In the equation, 10 ms represents the time taken when the node transitions from the second sleep state to the wake-up state during one signal period. 1.44 ms represents the time that the node stays up to receive the ACK frame.

Since the ACK frame does not include a node wake-up information field

Compared to the case, the time for the node to wake up for receiving the ACK frame is shorter.

In the case of a node to which the node wake-up method is applied according to an embodiment of the present invention, if the node does not wake up to receive the beacon frame because there is no change in the network, the average power consumption is about 0.913 mW, and in the general node, 1.070 Calculated in mW, the node wakeup method according to an embodiment of the present invention reduces the average power consumption by 14.7% compared to the normal node wakeup method. In addition, when the beacon frame reception including the changed network information is set every 10 s with the signal period n as 10, the node to which the node wake-up method according to the embodiment of the present invention is applied has an average power consumption of 0.9289 mW. The average power consumption is reduced by 13.2% compared with the normal node wake-up method.

According to an embodiment of another aspect of the present invention, a node receives an ACK frame including information for waking up the node, and the node receiving the ACK frame is in a wake-up state during a beacon frame reception period. A wake-up node may receive a beacon frame from a coordinator, and the node may provide a data communication method of transmitting a data frame to the coordinator.

The node wake-up method according to an embodiment of the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic media such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the embodiments described, and all the things that are equivalent to or equivalent to the scope of the claims as well as the following claims will belong to the scope of the invention.

Claims (11)

In the node wake-up method of a wireless body area network,
Receiving, by a node, an ACK frame containing information for waking up the node; And
Waking up the node receiving the ACK frame;
Node wakeup method comprising a. The method of claim 1,
The ACK frame includes a MAC header field;
An acknowledgment information field of the data frame; And
Node wakeup information field;
Node wakeup method comprising a. The method of claim 2,
And assigning a 1-bit field to the Mac header so that the node wakes up when the 1-bit field of the ACK frame received by the node has a value of 1. The method according to claim 1 or 2,
And the information for waking up the node includes signal period information on which the node wakes up. Receiving, by a node, an ACK frame containing information for waking up the node;
Waking up the node receiving the ACK frame; And
Receiving, by the wakeup node, a beacon frame; Data communication method comprising a. An ACK frame receiving unit which receives an ACK frame including information for waking up the node;
Beacon frame receiving unit for receiving a beacon frame; And
A controller configured to wake up the beacon frame receiver by receiving the ACK frame;
Node containing. The method according to claim 6,
The ACK frame includes a MAC header field;
An acknowledgment information field of the data frame; And
Node wakeup information field;
Node comprising a. The method of claim 7, wherein
And assigning a 1-bit field to the Mac header so that the node wakes up when the 1-bit field of the ACK frame received by the node has a value of 1. The method according to claim 6 or 7,
And the information for waking up the node includes signal period information at which the node wakes up. An ACK frame transmitter for transmitting an ACK frame including information for waking up the node; And
Beacon frame transmitter for transmitting a beacon frame;
Coordinator comprising a. A computer-readable recording medium having recorded thereon a program for performing the method of any one of claims 1 to 3.

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