KR101959017B1 - Wireless sensor networks and method of processing asymmetric traffic of the same - Google Patents

Abstract

Disclosed are a wireless sensor network and an asymmetric traffic processing method thereof capable of adjusting a message retransmission period (backoff). According to an embodiment of the present invention, the asymmetric traffic processing method of the wireless sensor network including a sink node and at least one sensor node comprises: a step in which a first sensor node transmits to the sink node first uplink data or a first request message for transmission of the first uplink data; a step in which the first sensor node sets a first message reception timer for a first confirmation message of the sink node for the first uplink data or a first response message of the sink node for the first request message; and a step in which the first sensor node retransmits the first uplink data or the first request message to the sink node if the first confirmation message or the first response message is not received from the sink node until the first message reception timer expires. The step of setting the first message reception timer includes a step in which the first message reception timer is set by reflecting a delay time due to at least one of a second response message of the sink node for a second request message transmitted to the sink node for transmission of first downlink data of the sink node by the first sensor node and transmission of second uplink data by a second sensor node, and a second confirmation message of the sink node for third uplink data transmitted to the sink node by a third sensor node.

Description

TECHNICAL FIELD [0001] The present invention relates to a wireless sensor network and a method for processing asymmetric traffic,

The present invention relates to a wireless sensor network and its asymmetric traffic processing method.

The underwater sensor network is composed of a sink node and a sensor node for the purpose of disaster prevention, strategic monitoring and environmental information collection in the underwater environment. First, the sink node has both an underwater communication interface for communicating with the sensor nodes and a terrestrial communication interface for communicating with the server or the user, thereby mediating acquired data or control information in the middle, and managing the sensor nodes . The sensor nodes transmit the acquired information to the sink node and reflect the control information received from the sink node.

Generally, uplink and downlink traffic are asymmetrical in a data collecting network operated for applications such as strategic monitoring, environmental information collection, and disaster control. That is, uplink traffic transmitted to a user by a plurality of terminals among the total traffic occupies the majority, whereas only downlink traffic for network control and management is only a small amount.

However, since the signaling procedures of existing underwater sensor networks are basically designed without considering traffic asymmetry and underwater channel characteristics under a half-duplex scheme, they can not efficiently utilize communication resources. Therefore, in order to improve the network performance, considering the traffic asymmetry and the underwater channel characteristics, a signaling procedure capable of appropriately processing a large amount of uplink traffic and a small amount of downlink traffic through the limited bandwidth between the sink node and the sensor node Research is needed.

The sensor node and the sink node transmit and receive messages, and if the response to the transmitted message is not returned within a predetermined time, the sensor node and the sink node retransmit the message after back-off. Unlike the uplink, in which a unique bandwidth is allocated to each sensor node, a downlink to which a data message is transmitted from a sink node to a sensor node is a single band. Therefore, a delay occurs due to overlapping of a downlink process and an uplink response process. . Due to such a delay factor, the sink node or the sensor node may unnecessarily retransmit the message in a set short period, which increases the data transmission cost.

The present invention provides a wireless sensor network and an asymmetric traffic processing method capable of adjusting a message retransmission period (backoff) considering a message transmission delay due to overlapping of an uplink and a downlink.

The present invention also provides a wireless sensor network and an asymmetric traffic processing method for efficiently processing uplink and downlink traffic occurring asymmetrically through a limited bandwidth between a sink node and a sensor node.

The problems to be solved by the present invention are not limited to the above-mentioned problems. Other technical subjects not mentioned will be apparent to those skilled in the art from the description below.

The asymmetric traffic processing method of a wireless sensor network according to one aspect of the present invention is a method of asymmetric traffic processing in a wireless sensor network including a sink node and at least one sensor node, Transmitting a first request message for transmission of one uplink data to the sink node; The first sensor node establishing a first message reception timer for the first acknowledgment message of the sink node for the first uplink data or the first acknowledgment message of the sink node for the first request message; When the first acknowledgment message or the first acknowledgment message is not received from the sink node until the first message reception timer expires, the first sensor node transmits the first uplink data or the first request message Wherein the first sensor node is configured to transmit the first downlink data of the sink node and the second sensor node to the second sink node, The second response message of the sink node to the second request message transmitted to the sink node for the uplink data transmission and the second response message of the sink node to the third uplink data transmitted to the sink node by the third sensor node, And setting the first message reception timer to reflect the delay time due to at least one of the second acknowledgment messages.

Setting the first message reception timer comprises: determining whether the first sensor node has received the first downlink data transmission time, the second response message transmission time, and the second acknowledgment message transmission time, And setting the first message reception timer by summing the maximum transmission time with a predetermined reference time.

The asymmetric traffic processing method of the wireless sensor network may include: transmitting the second downlink data to the first sensor node by the sink node; Wherein the sink node reflects the delay time due to the third request message or the fourth uplink data transmitted by the first sensor node to the sink node for transmission of the fourth uplink data, Setting a second message reception timer for a third acknowledgment message of the first sensor node for data; And transmitting, by the sink node, the second downlink data to the first sensor node when the third acknowledgment message is not received until the second message reception timer expires .

Setting the second message reception timer: when the third request message is received from the first sensor node within a predetermined reference time, the sink node transmits the reference time and the first transmission time of the third request message To set the second message reception timer; When the fourth uplink data is received from the first sensor node within the reference time, the sink node sums the second transmission time of the fourth uplink data with the reference time, Lt; / RTI >

The asynchronous traffic processing method of the wireless sensor network may include: when the sink node receives the first request message or the first uplink data from the first sensor node, checking whether a downlink channel is in use; When the downlink channel is in use, the sink node waits until the use of the downlink channel is terminated. After the use of the downlink channel is terminated, the sink node waits for the first response message or the first acknowledgment message And transmitting the first sensor node to the first sensor node.

The asynchronous traffic processing method of the wireless sensor network may include: when a plurality of first request messages or first uplink data are received from a plurality of first sensor nodes, the sink node transmits the plurality of first request messages or the first uplink data Determining priority of the plurality of first request messages or first uplink data based on the order of reception of each link data, data importance and urgency, and traffic characteristics; The sink node sequentially transmits a plurality of first response messages or first acknowledgment messages for the first request message or the first uplink data to the plurality of first sensor nodes according to the priority order ; ≪ / RTI >

According to another aspect of the present invention, there is provided a computer-readable recording medium on which a program for executing an asymmetric traffic processing method of the wireless sensor network is recorded.

According to another aspect of the present invention, there is provided a sink node of a wireless sensor network, the sink node comprising: a memory for storing a program for controlling data transmission with one or more sensor nodes of the wireless sensor network; A control unit for executing a program for controlling data transmission with the at least one sensor node; And a transmitter / receiver for communicating with the at least one sensor node, wherein the controller is configured to: transmit the first downlink data to the first sensor node; Wherein the first sensor node reflects a delay time due to the first request message or the first uplink data transmitted to the sink node for transmission of the first uplink data, Setting a message reception timer for a first acknowledgment message of one sensor node; And to retransmit the first downlink data to the first sensor node when the first acknowledgment message is not received until the message reception timer expires.

When the first request message is received from the first sensor node within a preset reference time, setting the message reception timer by summing the reference time and the first transmission time of the first request message; And if the first uplink data is received from the first sensor node within the reference time, the base station may sum up the reference time and the second transmission time of the first uplink data to set the message reception timer have.

Wherein the controller is configured to: determine whether a downlink channel is being used when receiving the first request message or the first uplink data from the first sensor node; And if the downlink channel is in use, waiting until the use of the downlink channel is terminated, and after a use of the downlink channel is terminated, a first response message for the first request message or a first uplink message for the first request message, And send a second acknowledgment message for the link data to the first sensor node.

The control unit may be configured to: when receiving a plurality of first request messages or first uplink data from a plurality of first sensor nodes, receiving sequence number, data importance, and urgency of each of the plurality of first request messages or first uplink data And determining a priority of the plurality of first request messages or first uplink data based on traffic characteristics; And transmit the plurality of first response messages or the second acknowledgment messages for the plurality of first request messages or the first uplink data to the plurality of first sensor nodes sequentially in accordance with the priority order.

According to another aspect of the present invention, there is provided a sensor node of a wireless sensor network, comprising: a memory for storing a program for controlling data transmission with a sink node of the wireless sensor network; A control unit for executing a program for controlling data transmission with the sink node; And a transmission / reception unit for communicating with the sink node, wherein the controller transmits a first request message for transmission of the first uplink data or the first uplink data to the sink node; Setting a message reception timer for a first acknowledgment message of the sink node for the first uplink data or a first acknowledgment message for the sink node for the first request message, A second response message of the sink node to a second request message transmitted from the second sensor node to the sink node for transmission of the second uplink data and a third response message of the third sensor node to the sink node, Setting the message reception timer to reflect a delay time due to at least one of the second acknowledgment messages of the sink node for uplink data; When the first acknowledgment message or the first acknowledgment message is not received from the sink node until the message reception timer expires, the first uplink data or the first request message is retransmitted to the sink node A sensor node of a wireless sensor network is provided.

Wherein the controller adds the first maximum transmission time, which is a sum of the transmission time of the first downlink data, the transmission time of the second response message and the transmission time of the second acknowledgment message, And to set a message reception timer.

Wherein the controller is configured to: determine whether an uplink channel with the sink node is in use when receiving second downlink data from the sink node; When the uplink channel is in use, the base station waits until the use of the uplink channel is terminated. After the use of the uplink channel is terminated, a third acknowledgment message for the second downlink data is transmitted to the sink node Lt; / RTI >

According to an embodiment of the present invention, there is provided a wireless sensor network and an asymmetric traffic processing method thereof, which can control a message retransmission period (backoff) considering a message transmission delay due to overlapping of an uplink and a downlink.

According to an embodiment of the present invention, a wireless sensor network and asymmetric traffic processing capable of efficiently processing uplink and downlink traffic occurring asynchronously between a sink node and a sensor node through a limited bandwidth between a sink node and a sensor node Method is provided.

The effects of the present invention are not limited to the effects described above. Unless stated, the effects will be apparent to those skilled in the art from the description and the accompanying drawings.

1 is a block diagram of a wireless sensor network according to an embodiment of the present invention.
2 is a configuration diagram of a sink node constituting a wireless sensor network according to an embodiment of the present invention.
3 is a configuration diagram of a sensor node constituting a wireless sensor network according to an embodiment of the present invention.
4 is a diagram illustrating frequency bands of sink nodes and sensor nodes constituting a wireless sensor network according to an embodiment of the present invention.
5 is a diagram illustrating an uplink and a downlink transmission process between a sink node and a sensor node constituting a wireless sensor network according to an embodiment of the present invention.
6 to 8 are flowcharts of an asymmetric traffic processing method of a wireless sensor network according to an embodiment of the present invention.

Other advantages and features of the present invention and methods of achieving them will be apparent by referring to the embodiments described hereinafter in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and the present invention is only defined by the scope of the claims. Although not defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly accepted by the generic art in the prior art to which this invention belongs. A general description of known configurations may be omitted so as not to obscure the gist of the present invention. In the drawings of the present invention, the same reference numerals are used as many as possible for the same or corresponding configurations. To facilitate understanding of the present invention, some configurations in the figures may be shown somewhat exaggerated or reduced.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises", "having", or "having" are intended to specify the presence of stated features, integers, steps, operations, components, Steps, operations, elements, parts, or combinations thereof, whether or not explicitly described or implied by the accompanying claims. It should be understood that terms such as " first "and" second "are used for the purpose of distinguishing a constituent element from another constituent element.

Used throughout this specification may refer to a hardware component such as, for example, software, FPGA or ASIC, as a unit for processing at least one function or operation. However, "to" is not meant to be limited to software or hardware. &Quot; to " may be configured to reside on an addressable storage medium and may be configured to play one or more processors.

As an example, the term '~' includes components such as software components, object-oriented software components, class components and task components, and processes, functions, attributes, procedures, Routines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided by the components and components may be performed separately by a plurality of components and components, or may be integrated with other additional components.

1 is a block diagram of a wireless sensor network according to an embodiment of the present invention. Referring to FIG. 1, a wireless sensor network according to an exemplary embodiment of the present invention includes one or more sink nodes and one or more sensor nodes. In one embodiment, the wireless sensor network may be an underwater sensor network. In an underwater sensor network, a sink node may be provided to float on the surface of the water. Wireless sensor networks may be constructed for various purposes, such as, for example, strategic monitoring, environmental information collection, disaster control, and the like, and are not limited to the specific purposes and uses illustrated.

The sink node may be provided to collect data from the sensor nodes. In one embodiment, the sink node floats over the water through the buoy, and can be located in a constant area of the surface of the water by mooring means (such as an anchor or mooring line).

The sensor nodes can be scattered and fixedly placed in the underwater region, or can be moved. The sensor nodes may be provided to perform various purposes such as monitoring, environmental information collection, or disaster prevention, and may include sensors for collecting information.

2 is a configuration diagram of a sink node constituting a wireless sensor network according to an embodiment of the present invention. 1 and 2, the sink node 10 includes a memory 12 for storing a program for controlling data transfer with the sensor node 20, a program for controlling data transfer with the sensor node 20, And a transceiver 16 for wirelessly communicating with the sensor node 20.

3 is a configuration diagram of a sensor node constituting a wireless sensor network according to an embodiment of the present invention. 1 to 3, the sensor node 20 includes a memory 22 for storing a program for controlling data transmission with the sink node 10, a program for controlling data transmission with the sink node 10, And a transmission / reception unit 26 for performing wireless communication with the sink node 10. The transmission /

The control unit 14 of the sink node 10 and the control unit 24 of the sensor node 20 are connected to each other via at least one central processing unit (CPU), a graphics processing unit (GPU) A general-purpose graphics processing unit (GPGPU), or the like.

Hereinafter, a method for data transmission in a wireless sensor network will be described. It is assumed that the system environment setting between the sink node and the third sensor node, that is, the frequency band allocation and the system parameter sharing are performed by the network initialization process.

4 is a diagram illustrating frequency bands of sink nodes and sensor nodes constituting a wireless sensor network according to an embodiment of the present invention. In one embodiment, the sink node utilizes a single band of 3-8 kHz for downlink data transmission, and each sensor node transmits the UL0 band (10- 14 kHz), the UL1 band (16-20 kHz), and the UL2 band (60-70 kHz). Unlike the uplink band, the unique downlink bands are not divided for each sensor node because the idle resources are increased and the network performance may be lowered when the bandwidth is divided for the less traffic of the downlink.

5 is a diagram illustrating an uplink and a downlink transmission process between a sink node and a sensor node constituting a wireless sensor network according to an embodiment of the present invention. In the case of the uplink, 4-way handshaking (CPQ-CPR-UL data-ACK) communication as shown in FIG. 5 is performed to apply link adaptation .

First, the sensor node exchanges a channel probe request (CPQ) message and a channel probe response (CPR) message with a sink node to check an uplink channel quality, And transmits uplink data (UL data) to the sink node by applying a modulation and coding scheme (MCS) level.

The sensor node can transmit uplink data (UL data) to the sink node only when the CPQ-CPR 2-way handshaking is successful. If the sensor node fails to receive the CPR or ACK message from the sink node, And retransmits the message to the sink node.

In order to improve the network performance, the sensor node specifies the size of the uplink data in the CPQ message instead of transmitting the fixed-length uplink data in every 4-way handshaking unit, Positive data can be transmitted at one time. Hereinafter, each 4-way handshaking unit of the uplink is referred to as an uplink session.

In the case of the downlink, since the traffic volume is small due to the nature of the data collecting network and there is no competition object for occupying the channel of the sink node, based on the simple 2-way handshaking (DL data-ACK) do. That is, when a downlink traffic occurs, the sink node transmits downlink data (DL data) immediately without a CPQ-CPR message exchange process as in the uplink, and receives an ACK message from the partner sensor node If not, the mobile station retransmits downlink data (DL data) after backoff for an arbitrary time. In most cases, since the DL data includes important control information, the link adaptation scheme is not applied for safe and reliable transmission, and the lowest modulation and coding (MCS) level is always applied. Hereinafter, each 2-way handshaking unit of the downlink is referred to as a downlink session.

Since the uplink and downlink bands are divided, uplink and downlink data can be simultaneously transmitted between the sink node and the sensor node through a full-duplex scheme. In this case, unlike the uplink in which the unique bandwidth is allocated to each sensor node, since the downlink is a single band, a delay may occur due to overlapping of the 4-way handshaking process of the uplink and the 2-way handshaking process of the downlink . The delay factor occurring in the uplink session occurs due to the overlapping of the uplink message reception timing with the downlink message transmission timing of the sink node.

6 to 8 are flowcharts of an asymmetric traffic processing method of a wireless sensor network according to an embodiment of the present invention. 6 shows a delay situation due to transmission of a downlink data (DL DATA) message of a sink node among delay factors occurring in an uplink session. The sink node receives the first request message (CPQ) or the first uplink data (UL DATA) message of the sensor node j while transmitting the downlink data (DL DATA) message.

Since the sink node has a downlink channel, the sink node transmits a first response message (CPR) for the first request message (CPQ) or a first response message (CPR) to the sensor node j after completing the transmission of the first downlink data And may transmit a first acknowledgment message (ACK) for uplink data (UL DATA).

또는

)이 발생하므로, 센서노드 j는 이를 고려하여 제 1 응답메시지(CPR) 또는 제 1 확인메시지(ACK)에 대한 메시지 수신 타이머를 설정한다.As a result, a delay due to the first downlink data (DL DATA) in the uplink session of the sensor node j

or

, The sensor node j sets a message reception timer for the first response message (CPR) or the first acknowledgment message (ACK) in consideration of this.

In one embodiment, the sensor node j calculates the time T (T _DL ) of the first downlink data (DL DATA) by adding the predetermined reference time T _R1 for the first response message (CPR) the transmission time of _{_CPR)} a first response message (set by the message reception timer of the CPR), and the reference time predetermined for the first acknowledgment message (ACK) (T _R2), a first downlink data (DL dATA) ( _{T_ACK} ), which is the sum of the first acknowledgment message (T _DL ), as the message reception timer for the first acknowledgment message (ACK).

The transmission time T _DL of the first downlink data DL DATA may be a preset value or a value obtained from a message of the first downlink data DL DATA transmitted from the sink node. For example, when the transmission length of the DL data transmitted from the sink node to the sensor node is set to have a fixed value, the transmission time corresponding to the transmission length of the DL data DL DATA is preset ( _{T_CPR} , _{T_ACK} ).

As another example, the sink node, the first down-link data in the first downlink data to be sent to the (DL DATA) sensor nodes by adding a transfer length value to the message, the reference time _{(T R1, T R2) (} DL DATA) The sensor node extracts the transmission length value of the downlink data in the message of the first downlink data (DL DATA) and transmits the transmission data corresponding to the transmission length value of the downlink data to determine the time (T _DL) may set a message reception timer (T _{_CPR,} T _{_ACK).}

When the first downlink data DL DATA is data transmitted from the sink node to another sensor node, the first sensor node can not know the transmission time of the first downlink data DL DATA. In this case, The message reception timer ( _{T_CPR} , _{T_ACK} ) can be set to reflect the transmission time of the link data (DL DATA).

FIG. 7 shows a delay situation due to the downlink CPR or ACK message transmission of the sink node among the delay factors occurring in the uplink session. 7, the sink node transmits a response message (CPR) to the sensor node 0 or an acknowledgment message (ACK) to the uplink data (UL DATA) Lt; RTI ID = 0.0 > (CPQ) < / RTI > Since the sink node has one downlink channel, the sink node can transmit a response message (CPR) to the sensor node # 1 after completing transmission of a response message (CPR) or acknowledgment message (ACK) to the sensor node # 0.

만큼의 지연이 발생하므로, 센서노드 1번은 이를 고려하여 응답메시지(CPR)에 대한 메시지 수신 타이머를 설정한다. 일 실시예로, 센서노드 1번은 응답메시지(CPR)에 대해 기설정된 기준 시간(T_R1)과, 센서노드 0번의 요청메시지에 대한 응답메시지(CPR)의 전송 시간(T_C)을 합산한 시간(T_{_CPR})을 응답메시지(CPR)에 대한 메시지 수신 타이머로 설정할 수 있다.As a result, in the uplink session of sensor node # 1

The sensor node # 1 sets the message reception timer for the response message (CPR) in consideration of this delay. In one embodiment, the sensor node 1 times the reference time set based on the response message (CPR) (T _R1) and the sensor node transmission time of the response message (CPR) for 0 single request message (T _C) for summing one hours ( _{T_CPR} ) to the message reception timer for the response message (CPR).

The transmission time (T _C ) of the response message (CPR) may be a predetermined value. For example, when the transmission length of the response message (CPR) transmitted from the sink node to the sensor node is set to have a fixed value, a transmission time corresponding to the transmission length of the response message (CPR) ( _{T_CPR} ).

On the other hand, even when the sink node transmits an acknowledgment message (ACK) for uplink data (UL DATA) to the sensor node # 0, the reception of the message of the sensor node # 1 may be delayed. In this case, the sensor node # 1 transmits the acknowledgment message (CPR) with a predetermined reference time (T _R1 ) and the acknowledgment message (ACK) transmission time (T _A ) to the uplink data (UL DATA) ( _{T_CPR} ) as the message reception timer for the response message (CPR).

Three delay factors occurring in the uplink session mentioned in FIG. 5 and FIG. 6 may appear at the same time. For example, when a request message (CPQ) transmitted from a sensor node j is received by a sink node, downlink data to be transmitted to the sensor node exists in the sink node, and at the same time, When the request message and the uplink data exist, the delay time due to the downlink data, the delay time due to the response message to the request message, and the delay time due to the confirmation message for the uplink data can all be applied. Therefore, the sensor node j can set a message reception timer by adding the delay time due to the downlink data of the sink node, the delay time due to the response message, and the delay time due to the confirmation message, together with the preset reference time have.

또는

)를 set 시킨 후 (

또는

), 현재 하향링크 채널이 사용 중인지 확인한다. 해당 하향링크 채널이 사용 중이 아닌 경우, 싱크노드는 즉시 센서노드 j를 향해 요청메시지(CPQ)에 대한 응답메시지(CPR) 또는 상향링크 데이터(UL DATA)에 대한 확인메시지(ACK)를 전송하고, 플래그 변수(

또는

)를 clear 시킨다(

또는

).In one embodiment, when a sink node receives a request message (CPQ) or an uplink data (UL DATA) message from a specific sensor node j,

or

) Is set

or

), It is checked whether the downlink channel is currently in use. If the downlink channel is not in use, the sink node immediately transmits a response message (CPR) to the sensor node j or an acknowledgment message (ACK) to the uplink data (UL DATA) The flag variable (

or

Clear

or

).

및

)가 set 상태로 될 수 있다. 이때, 싱크노드는 특정 기준에 따라 센서노드들에게 우선순위를 부여하여, 우선순위가 높은 센서노드 순서대로 응답메시지(CPR) 또는 확인메시지(ACK)를 응답하고, 플래그 변수(

또는

)를 clear 시킨다(

또는

).On the other hand, when the downlink channel is in use, the sink node waits until the use of the downlink channel is ended. Since the sink node transmits data to a plurality of sensor nodes, a plurality of flag variables

And

) May be set. At this time, the sink node assigns priority to the sensor nodes according to a specific criterion, responds to the response message (CPR) or acknowledgment message (ACK) in the order of the higher-priority sensor node,

or

Clear

or

).

In one embodiment, the sink node may receive a request message (CPQ) or an uplink data (UL DATA) message according to a first-in first-out (FIFO) scheme considering the order of reception of messages transmitted from a plurality of sensor nodes First, a high priority can be given according to the order of received sensor nodes. However, priorities can be determined by reflecting various parameters such as traffic characteristics, user setting, data importance or urgency according to the case.

For example, if the uplink data (UL DATA) of the sensor node 1 has higher importance or urgency even though the request message (CPQ) of the sensor node 0 is received before the request message (CPQ) of the sensor node 1, The node may transmit a response message (CPR) to the sensor node 1 first. As a result, each sensor node can consider the delay according to the flag variable set state of other sensor nodes when setting a message reception timer for a response message (CPR) or an acknowledgment message (ACK).

만큼 지연이 발생하므로, 싱크노드는 이를 고려하여 확인메시지(ACK)에 대한 메시지 수신 타이머를 설정한다.The delay factor occurring in the downlink session occurs due to overlapping of the uplink message transmission timing of the receiving sensor node and the downlink message receiving process. The delay of the downlink session is not related to the overlap of the uplink message transmission timing of the sensor node other than the reception target. FIG. 8 shows a delay situation due to transmission of a request message (CPQ) or uplink data (UL DATA) message of the reception target sensor node j. First, the sensor node j may receive a downlink data (DL DATA) message of a sink node during transmission of a request message (CPQ) or an uplink data (UL DATA) message. Since the uplink channel between the sensor node j and the sink node is one, the sensor node j transmits a confirmation message (CPQ) or uplink data (UL DATA) message to the sink node after completing the transmission of the uplink message ACK). As a result, in the sink node's downlink session

The sink node sets a message reception timer for an acknowledgment message (ACK) in consideration of this delay.

In one embodiment, when a sensor node's request message (CPQ) is received within a predetermined reference time (T _R3 ) for an acknowledgment message (ACK), the sink node transmits the sensor node's request message (CPQ) confirmed _C) one hours (T _{_ACK1)} aggregates can be set to a timer message is received for the message (ACK).

In another embodiment, when the uplink data (UL DATA) of the sensor node is received within a preset reference time (T _R3 ) for the acknowledgment message (ACK), the sink node transmits a predetermined reference time ( _{T_ACK2} ) obtained by adding the transmission time (T _R3 ) of the uplink data (UL DATA) and the transmission time (T _DL ) of the uplink data (UL DATA) to the message reception timer for the acknowledgment message (ACK).

The transmission time T _C of the request message CPQ and / or the transmission time T _UL of the uplink data UL DATA may be a preset value, or may be a predetermined value, (UL DATA) message. For example, when a transmission length of a request message (CPQ) or uplink data (UL DATA) transmitted from a sensor node to a sink node is set to have a fixed value, transmission of a corresponding request message or uplink data (UL DATA) The transmission time corresponding to the length can be set in advance and reflected in the message reception timers _{T_ACK1} and _{T_ACK2} .

As another example, the sensor node, the request message (CPQ) or uplink data (UL DATA) request message (CPQ) or uplink in addition to the transfer length value to the message to be transmitted to the sink node, the reference time (T _R3) of (UL DATA) is received from the sensor node to the sink node, the sink node extracts the transmission length value from the message of the request message (CPQ) or the uplink data (UL DATA), and transmits the transmission It is also possible to set the message reception timers ( _{T_ACK1} , _{T_ACK2} ) for the confirmation message (ACK) by determining the time (T _C, T _UL ).

변수를 set 시킨 후 (

), 현재 상향링크 채널이 사용 중인지 확인한다. 해당 상향링크 채널이 사용 중이 아닌 경우, 즉시 싱크노드를 향해 확인메시지(ACK)를 전송하고

변수를 clear 시킨다(

). 반면, 해당 상향링크 채널이 사용 중인 경우, 상향링크 채널 사용이 종료될 때까지 대기한다. 본 발명에서는 단일의 싱크노드를 가정하므로, 상향링크 세션 지연 상황과는 달리 복수의 플래그 변수

가 set 상태일 수 없다.When the sensor node j receives the downlink data (DL DATA) message from the sink node,

After setting the variable (

), It is confirmed whether the uplink channel is currently being used. If the uplink channel is not in use, an acknowledgment message (ACK) is immediately sent to the sink node

Clear the variable (

). On the other hand, if the uplink channel is in use, the mobile station waits until the use of the uplink channel is ended. In the present invention, since a single sink node is assumed, unlike the uplink session delay situation,

Can not be set.

The method according to an embodiment of the present invention can be realized in a general-purpose digital computer that can be created as a program that can be executed by a computer and operates the program using a computer-readable recording medium. The computer readable recording medium may be a volatile memory such as SRAM (Static RAM), DRAM (Dynamic RAM), SDRAM (Synchronous DRAM), ROM (Read Only Memory), PROM (Programmable ROM), EPROM (Electrically Programmable ROM) Non-volatile memory such as EEPROM (Electrically Erasable and Programmable ROM), flash memory device, Phase-change RAM (PRAM), Magnetic RAM (MRAM), Resistive RAM (RRAM), Ferroelectric RAM But are not limited to, optical storage media such as CD ROMs, DVDs, and the like.

It is to be understood that the above-described embodiments are provided to facilitate understanding of the present invention, and do not limit the scope of the present invention, and it is to be understood that various modified embodiments are also within the scope of the present invention. It is to be understood that the technical scope of the present invention should be determined by the technical idea of the claims and the technical scope of protection of the present invention is not limited to the literary description of the claims, Of the invention.

10: sink node
12: Memory
14:
16: Transmitting /
20: Sensor node
22: Memory
24:
26: Transmitting /

Claims (14)

1. A method for asymmetric traffic processing in a wireless sensor network including a sink node and at least one sensor node,
Transmitting a first request message for transmission of the first uplink data or the first uplink data to the sink node by the first sensor node;
The first sensor node establishing a first message reception timer for the first acknowledgment message of the sink node for the first uplink data or the first acknowledgment message of the sink node for the first request message; And
When the first acknowledgment message or the first acknowledgment message is not received from the sink node until the first message reception timer expires, the first sensor node transmits the first uplink data or the first request message To the sink node,
Setting the first message reception timer comprises:
The first sensor node transmits the first downlink data of the sink node and the second sensor node to the second request message transmitted to the sink node for transmission of the second uplink data, Setting a first message reception timer by reflecting a delay time due to at least one of a response message and a second acknowledgment message of the sink node for third uplink data transmitted from the third sensor node to the sink node; Including,
A method for processing asymmetric traffic in a wireless sensor network. The method according to claim 1,
Setting the first message reception timer comprises:
Wherein the first sensor node calculates a first maximum transmission time by summing the transmission time of the first downlink data, the transmission time of the second response message, and the transmission time of the second acknowledgment message, And setting the first message reception timer.
A method for processing asymmetric traffic in a wireless sensor network. The method according to claim 1,
The sink node sending second downlink data to the first sensor node;
Wherein the sink node reflects the delay time due to the third request message or the fourth uplink data transmitted by the first sensor node to the sink node for transmission of the fourth uplink data, Setting a second message reception timer for a third acknowledgment message of the first sensor node for data; And
Further comprising: if the third acknowledgment message is not received until the second message reception timer expires, the sink node retransmits the second downlink data to the first sensor node.
A method for processing asymmetric traffic in a wireless sensor network. The method of claim 3,
Setting the second message reception timer comprises:
When the third request message is received from the first sensor node within a preset reference time, the sink node adds the first transmission time of the third request message and the reference time to set the second message reception timer To do; And
When the fourth uplink data is received from the first sensor node within the reference time, the sink node adds the second transmission time of the fourth uplink data and the reference time to transmit the second message reception timer Setting,
A method for processing asymmetric traffic in a wireless sensor network. The method according to claim 1,
Upon receipt of the first request message or the first uplink data from the first sensor node, the sink node verifies that the downlink channel is in use; And
Wherein if the downlink channel is in use, the sink node waits until the use of the downlink channel is terminated, and transmits the first response message or the first acknowledgment message after the use of the downlink channel is terminated Transmitting to the first sensor node,
A method for processing asymmetric traffic in a wireless sensor network. The method according to claim 1,
When a plurality of first request messages or first uplink data are received from a plurality of first sensor nodes, the sink node transmits the reception order number, data importance, and urgency of each of the plurality of first request messages or first uplink data, Determining a priority of the plurality of first request messages or first uplink data based on traffic characteristics; And
The sink node sequentially transmitting a plurality of first response messages or first acknowledgment messages for the first request message or the first uplink data to the plurality of first sensor nodes sequentially according to the priority order; ≪ / RTI >
A method for processing asymmetric traffic in a wireless sensor network. A computer-readable recording medium on which a program for executing an asymmetric traffic processing method of a wireless sensor network according to any one of claims 1 to 6 is recorded. A sink node of a wireless sensor network,
The sink node comprising:
A memory for storing a program for controlling data transmission with one or more sensor nodes of the wireless sensor network;
A control unit for executing a program for controlling data transmission with the at least one sensor node; And
And a transmission / reception unit for communicating with the at least one sensor node,
The control unit includes:
Transmitting first downlink data to a first sensor node;
Wherein the first sensor node reflects a delay time due to the first request message or the first uplink data transmitted to the sink node for transmission of the first uplink data, Setting a message reception timer for a first acknowledgment message of one sensor node; And
And to retransmit the first downlink data to the first sensor node when the first acknowledgment message is not received until the message reception timer expires,
A sink node of a wireless sensor network. 9. The method of claim 8,
The control unit includes:
If the first request message is received from the first sensor node within a predetermined reference time, summing the reference time and the first transmission time of the first request message to set the message reception timer; And
And to set the message reception timer by summing the reference time and a second transmission time of the first uplink data when the first uplink data is received from the first sensor node within the reference time,
A sink node of a wireless sensor network. 10. The method according to claim 8 or 9,
The control unit includes:
Upon receiving the first request message or the first uplink data from the first sensor node, checking whether a downlink channel is in use; And
Wherein the control unit waits until the use of the downlink channel is terminated when the downlink channel is in use and the first response message for the first request message or the first uplink message for the first request message after the use of the downlink channel is terminated, And send a second acknowledgment message for the data to the first sensor node.
A sink node of a wireless sensor network. 11. The method of claim 10,
The control unit includes:
When a plurality of first request messages or first uplink data are received from a plurality of first sensor nodes, the receiving order of each of the plurality of first request messages or the first uplink data, the data importance and urgency, Determining a priority of the plurality of first request messages or first uplink data based on the first request message or the first uplink data; And
And transmit the plurality of first response messages or the second acknowledgment messages for the plurality of first request messages or the first uplink data sequentially to the plurality of first sensor nodes according to the priority,
A sink node of a wireless sensor network. A sensor node in a wireless sensor network,
The sensor node comprising:
A memory for storing a program for controlling data transmission with a sink node of the wireless sensor network;
A control unit for executing a program for controlling data transmission with the sink node; And
And a transmission / reception unit for communicating with the sink node,
The control unit includes:
Transmitting a first request message for transmission of the first uplink data or the first uplink data to the sink node;
Setting a message reception timer for a first acknowledgment message of the sink node for the first uplink data or a first acknowledgment message for the sink node for the first request message, A second response message of the sink node to a second request message transmitted from the second sensor node to the sink node for transmission of the second uplink data and a third response message of the third sensor node to the sink node, Setting the message reception timer to reflect a delay time due to at least one of the second acknowledgment messages of the sink node for uplink data; And
And to retransmit the first uplink data or the first request message to the sink node when the first acknowledgment message or the first acknowledgment message is not received from the sink node until the message reception timer expires felled,
A sensor node in a wireless sensor network. 13. The method of claim 12,
Wherein the controller adds the first maximum transmission time, which is a sum of the transmission time of the first downlink data, the transmission time of the second response message and the transmission time of the second acknowledgment message, Configured to set a message reception timer,
A sensor node in a wireless sensor network. The method according to claim 12 or 13,
The control unit includes:
Upon receiving the second downlink data from the sink node, checking whether the uplink channel with the sink node is in use; And
If the uplink channel is in use, waits until the use of the uplink channel is terminated. After the use of the uplink channel is terminated, a third acknowledgment message for the second downlink data is transmitted to the sink node ≪ / RTI >
A sensor node in a wireless sensor network.

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