KR102545466B1 - Network system based on industrial internet of things - Google Patents

Abstract

The present invention relates to a network system based on the Industrial Internet of Things, and a wireless communication device of a network system according to an embodiment includes a packet receiver for receiving a packet corresponding to at least one flow, and at least one of the packets. stores a network parameter piggybacked in a packet corresponding to a flow of the flow, and transmits a time slot for the flow based on at least one of the priority of the flow and the stored network parameter ) and a packet transmission unit for transmitting a packet corresponding to the at least one flow in the controlled time slot.

Description

Network system based on industrial internet of things {NETWORK SYSTEM BASED ON INDUSTRIAL INTERNET OF THINGS}

The present invention relates to a network system based on the Industrial Internet of Things (IIoT), and more particularly, to a technical idea that guarantees real-time adaptability in the Industrial Internet of Things (IIoT).

WirelessHART, an industrial wireless communication standard protocol, is a representative centralized wireless sensor and actuator network (WSAN), and its main purpose is to control industrial equipment based on wireless communication for industrial process automation.

One of the key issues of WSAN is to compensate for the stability of equipment control. However, it is difficult to guarantee the stability of system control due to the uncertainty of data transmission rate and transmission delay due to the characteristics of current wireless communication.

Accordingly, network resource distribution optimization algorithms that adaptively change the data transmission period and transmission rate (network parameters) have been proposed in the past to ensure stability, but the network transmits the parameters selected through the algorithm to the network communication device due to its structural characteristics. A specific time interval (dissemination interval or operation message slot) for This characteristic means that even if a problem (disturbation) occurs in the network and physical system, it cannot respond until the corresponding section arrives.

In other words, the difficulty in guaranteeing real-time adaptability of the network is a fundamental limitation of centralized networks, and research to improve this is not in progress.

Korean Patent Registration No. 10-1952810, "Power Link Wireless HART Gateway for Industrial Automation" Korean Patent Registration No. 10-1174406, "Low Power MAC Communication Method for Sensor Network Based on Environmental Energy Acquisition" Korean Patent Publication No. 10-2020-0015750, "Communication method, network node, and radio access network system"

Park, Pangun, Piergiuseppe Di Marco, and Karl Henrik Johansson. "Cross-layer optimization for industrial control applications using wireless sensor and actuator mesh networks." IEEE Transactions on Industrial Electronics 64.4 (2016): 3250-3259. Hong, Shengyan, et al. "On-line data link layer scheduling in wireless networked control systems." 2015 27th Euromicro Conference on Real-Time Systems. IEEE, 2015.

An object of the present invention is to provide a network system in which each node can determine its own transmission time slot without control according to a global schedule.

In addition, the present invention intends to provide a network system capable of transmitting data by itself to each node and adapting to changed network parameters in real time.

In addition, the present invention is intended to provide a network system capable of preventing collision of transmission packets due to the absence of a global schedule by artificially mismatching transmission times.

In addition, the present invention is intended to provide a network system that can more quickly respond to disturbances in the system through guarantees of real-time adaptability, thereby guaranteeing high stability.

A wireless communication device of a network system according to an embodiment of the present invention includes a packet receiver for receiving packets corresponding to at least one flow, and piggybacking packets corresponding to the at least one flow. ), and a time slot control unit for controlling a transmission time slot for the flow based on at least one of the priority of the flow and the stored network parameter, and the controlled A packet transmission unit for transmitting a packet corresponding to the at least one flow in a time slot may be included.

According to one side, the network parameters may include a parameter related to a transmission period and a parameter related to the number of retransmission slots per link.

According to one side, the time slot control unit may control a transmission offset time corresponding to a timing of transmitting a packet corresponding to the flow within the transmission time slot based on the priority of the flow.

According to one side, the time slot controller receives a packet corresponding to the first flow and a packet corresponding to a second flow having a lower priority than the first flow, at the first transmission offset time of the transmission time slot. A packet corresponding to the first flow may be controlled to be transmitted.

According to one side, when the packet corresponding to the first flow and the packet corresponding to the second flow are received, the time slot control unit delays the transmission time slot by a predetermined first time from the first transmission offset time. At a transmission offset time of 2, the packet corresponding to the second flow can be controlled to be transmitted.

According to one side, when the packet corresponding to the second flow is received, the time slot control unit corresponds to the first flow until a third offset time of the transmission time slot delayed by a predetermined second time from the first offset time It can be controlled to wait for the reception of packets to be received.

A network system according to an embodiment of the present invention includes a plurality of nodes constituting a network and a controller for setting a transmission path corresponding to at least one flow in the network, and among the plurality of nodes, the transmission path At least one corresponding relay node receives a packet corresponding to the flow, stores a network parameter piggybacked in the received packet, and stores the priority of the flow and the A transmission time slot for the flow may be controlled based on at least one of the stored network parameters.

According to one side, each of the plurality of nodes may include sensors and actuators equipped with half-duplex radio transceivers.

According to one side, the network parameter may include a parameter related to a transmission period and a parameter related to the number of retransmission slots per link.

According to one side, a source node corresponding to the transmission path among the plurality of nodes may generate the packet by receiving a message corresponding to the flow from the controller, and piggyback the network parameter to the packet.

According to one side, the at least one relay node may control a transmission offset time corresponding to a timing of transmitting a packet corresponding to the flow to a next node within the transmission time slot based on the priority of the flow.

According to one side, when the at least one relay node receives a packet corresponding to the first flow and a packet corresponding to a second flow having a lower priority than the first flow, the first transmission offset time of the transmission time slot A packet corresponding to the first flow may be transmitted to the next node.

According to one side, when the at least one relay node receives a packet corresponding to the first flow and a packet corresponding to the second flow, the transmission time slot delayed by a predetermined first time than the first transmission offset time A packet corresponding to the second flow may be transmitted to the next node at the second transmission offset time of .

According to one side, when the at least one relay node receives a packet corresponding to the second flow, the first flow until a third offset time of the transmission time slot delayed by a preset second time than the first offset time It is possible to wait for reception of packets corresponding to .

According to an embodiment of the present invention, each node can determine its own transmission time slot without control according to a global schedule.

In addition, the present invention can transmit data by itself to each node and adapt to changed network parameters in real time.

In addition, the present invention can prevent collision of transport packets due to the absence of a global schedule by artificially mismatching transmission times.

In addition, the present invention can more quickly respond to disturbances in the system through the guarantee of real-time adaptability, thereby guaranteeing high stability.

1 is a diagram for explaining a network system according to an embodiment.
2 is a diagram for explaining a wireless communication device of a network system according to an embodiment.
3 is a diagram for explaining a configuration example of a node of a network system according to an embodiment.
4A to 4C are diagrams for explaining an example of controlling a transmission time slot in a node of a network system according to an embodiment.
5A and 5B are diagrams illustrating an example of optimizing a third offset time in a network system according to an embodiment.
6A to 7B are diagrams illustrating performance measurement results of a network system according to an exemplary embodiment.

Hereinafter, various embodiments of this document will be described with reference to the accompanying drawings.

Examples and terms used therein are not intended to limit the technology described in this document to specific embodiments, and should be understood to include various modifications, equivalents, and/or substitutes of the embodiments.

In the following description of various embodiments, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the invention, the detailed description will be omitted.

In addition, terms to be described below are terms defined in consideration of functions in various embodiments, and may vary according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

In connection with the description of the drawings, like reference numerals may be used for like elements.

Singular expressions may include plural expressions unless the context clearly indicates otherwise.

In this document, expressions such as "A or B" or "at least one of A and/or B" may include all possible combinations of the items listed together.

Expressions such as "first," "second," "first," or "second," may modify the corresponding components regardless of order or importance, and are used to distinguish one component from another. It is used only and does not limit the corresponding components.

When a (e.g., first) element is referred to as being "(functionally or communicatively) connected" or "connected" to another (e.g., second) element, an element is referred to as another (e.g., second) element. It may be directly connected to, or connected through another component (eg, a third component).

In this specification, "configured to (or configured to)" means "suitable for," "having the ability to," "changed to" depending on the situation, for example, hardware or software ," can be used interchangeably with "made to," "capable of," or "designed to."

In some contexts, the expression "device configured to" can mean that the device is "capable of" in conjunction with other devices or components.

For example, the phrase "a processor configured (or configured) to perform A, B, and C" may include a dedicated processor (eg, embedded processor) to perform the operation, or by executing one or more software programs stored in a memory device. , may mean a general-purpose processor (eg, CPU or application processor) capable of performing corresponding operations.

Also, the term 'or' means 'inclusive or' rather than 'exclusive or'.

That is, unless otherwise stated or clear from the context, the expression 'x employs a or b' means any one of the natural inclusive permutations.

In the specific embodiments described above, components included in the invention are expressed in singular or plural numbers according to the specific embodiments presented.

However, singular or plural expressions are selected appropriately for the presented situation for convenience of explanation, and the above-described embodiments are not limited to singular or plural components, and even components expressed in plural are composed of a singular number or , Even components expressed in the singular can be composed of plural.

Meanwhile, in the description of the invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the technical idea contained in the various embodiments.

Therefore, the scope of the present invention should not be limited to the described embodiments and should not be defined, but should be defined by not only the claims to be described later, but also those equivalent to these claims.

1 is a diagram for explaining a network system according to an embodiment.

Referring to FIG. 1 , the network system 100 according to an embodiment may determine its own transmission time slot without control according to a global schedule in each node.

In addition, the network system 100 can transmit data by itself to each node and adapt to changed network parameters in real time.

In addition, the network system 100 can artificially mismatch transmission times to prevent transmission packet collision due to the absence of a global schedule.

In addition, the network system 100 can respond more quickly when a disturbance occurs in the system through guaranteeing real-time adaptability, thereby guaranteeing high stability.

To this end, the network system 100 according to an embodiment may include a plurality of nodes (N) and a controller 120 constituting the network 110 .

According to one side, each of the plurality of nodes N may include sensors and actuators equipped with half-duplex radio transceivers. In other words, the network 110 may be a multi-hop based wireless sensor and actuator network (WSAN).

For example, sensors provided in each node N may derive measurement values by being directly connected to a plant, and periodically transmit the derived measurement values to the controller 120 through a multi-hop network. .

In addition, the controller 120 may generate a control command and transmit a message including the generated control command to a node N corresponding to the control command through a multi-hop network, and the plant connected to the node N may control The operation of the actuator may be controlled based on the command.

According to one side, the controller 120 is implemented as a central server, and can measure the status of both the network 110 and the plant to adjust network parameters while controlling all plants at the same time.

The controller 120 according to an embodiment may set a transmission path corresponding to at least one flow in the network 110 .

Specifically, the controller 120 may set a source node and a destination node corresponding to the flow, set at least one transmission path connecting the set source node and destination node, and at least one At least one relay node may be included on the transmission path of .

According to one side, nodes (a source node, at least one relay node, and a destination node) located on a transmission path corresponding to the same flow may be synchronized in time with each other.

로 네트워크(110)를 모델링할 수 있으며, 여기서 V는 노드 집합(set)을 나타내고 E는 노드 집합 V를 구성하는 노드와 연결된 링크 집합을 나타낸다. 또한, 링크

는 소스 노드 e_s와 목적지 노드 e_d 즉,

간의 링크를 나타낸다. More specifically, the controller 120 is a directed graph

The network 110 can be modeled as , where V represents a set of nodes and E represents a set of links connected to nodes constituting the set of nodes V. Also, link

is the source node e _s and the destination node e _d , that is,

represents the link between them.

The controller 120 may set at least one transmission path for each flow from a source node to a destination node based on a preset source routing policy.

에 대한 전송 경로

는 n 개의 링크

로 구현될 수도 있다.Also, flow

transmission path for

is n links

may be implemented as

는

로 특성화될 수 있으며, 여기서 T_i는 플로우에 대응되는 전송주기(transmission period), C_i는 확률적 실행시간(probabilistic execution time, pET), D_i는 전송주기 T_i와 같은 상대적인 기한(relative deadline)을 나타낸다.For example, flow

Is

, where T _i is a transmission period corresponding to the flow, C _i is a probabilistic execution time (pET), and D _i is a relative deadline such as T _i ).

The controller 120 may design a stochastic execution time (pET) in consideration of a packet loss probability per link.

According to one side, when a plurality of flows exist, the controller 120 may determine a priority for each of the plurality of flows.

)로 설정하고, 제2 플로우를 상대적으로 우선순위가 낮은 플로우(

)로 설정할 수 있다. For example, when a first flow and a second flow exist, the controller 120 assigns the first flow to a flow having a higher priority (

), and the second flow is a relatively low priority flow (

) can be set.

According to one side, the source node corresponding to the transmission path may receive a message corresponding to the flow from the controller 120, generate a packet, and piggyback network parameters to the generated packet. A packet whose parameters are piggybacked can be transmitted to the next node (relay node) on the transmission path.

For example, the source node may set and piggyback network parameters based on messages received from the controller 120 . Also, the source node may receive a message in which the network parameters are reflected from the controller 120 and piggyback the received network parameters.

According to one side, the network parameters may include a parameter related to a transmission period and a parameter related to the number of retransmission slots per link. Here, the parameter related to the transmission period means a parameter related to the period during which the source node generates packets, and the parameter related to the number of retransmission slots per link is the threshold of the number of attempts to transmit packets in each node corresponding to the transmission path. can mean value.

In addition, the packet may include flow ID information and a plant control command corresponding to the flow.

According to one side, the source node may reset network parameters based on at least one of a request signal received from at least one node among nodes located on the transmission path and monitoring results of communication states of nodes located on the transmission path. . In addition, the source node may piggyback the reset parameter into a packet and transmit it to the next node on the transmission path.

Specifically, piggyback is a mechanism for storing network parameters in packets to be transmitted. The network system 100 according to an embodiment is a general centralized approach that broadcasts information to all network nodes (ie, a global schedule) and Otherwise set/changed network parameters may be transmitted only to nodes located on a flow routing path, that is, a transmission path corresponding to at least one flow.

That is, the network system 100 according to an embodiment can guarantee the real-time adaptability of the network through the determination of the immediate network parameter of the source node, and through this, it can respond more quickly when a disturbance occurs in the system to ensure high stability. .

Meanwhile, at least one relay node corresponding to the transmission path receives a packet corresponding to the flow, stores a network parameter piggybacked in the received packet, and based on at least one of the priority of the flow and the stored network parameter A transmission time slot for a flow can be controlled.

In other words, nodes corresponding to the transmission path can determine their own transmission time slots without receiving a global schedule.

According to one side, at least one relay node may control a transmission time slot based on a radio event that occurs.

For example, the radio event may be an event according to at least one of a packet reception operation and a transmission operation according to at least one flow, and preferably, the radio event is a packet priority and transmission according to at least one flow. This may mean an event according to a packet collision type.

Events according to collision types of transport packets will be described in more detail with reference to FIGS. 4A to 4C.

Specifically, at least one relay node transmits the packet corresponding to the flow within the transmission time slot based on the priority of the flow to the next node (next relay node or destination node) on the transmission path Transmission offset time corresponding to the point in time can control.

According to one side, when at least one relay node receives a packet corresponding to the first flow and a packet corresponding to the second flow having a lower priority than the first flow, the first flow at the first transmission offset time of the transmission time slot A packet corresponding to can be transmitted to the next node.

In addition, at least one relay node may transmit a packet corresponding to the first flow to the next node at a second transmission offset time of a transmission time slot delayed by a predetermined first time from the first transmission offset time.

Preferably, the first transmission offset time is 0 ms, which is the start time of the transmission time slot, and the second transmission offset time may be 3 ms.

According to one side, when receiving a packet corresponding to the second flow, at least one relay node waits for reception of a packet corresponding to the first flow until a third offset time delayed by a preset second time from the first offset time can Preferably, the third offset time may be 5 ms.

Specifically, when at least one relay node receives only a packet corresponding to the second flow without receiving a packet corresponding to the first flow, up to the third offset time of the first transmission time slot (eg, 0ms to 5ms) It is possible to wait for reception of a packet corresponding to flow 1, and if the packet corresponding to the first flow is not received during the waiting time until the third offset time of the first transmission time slot, the third offset time of the first transmission time slot After that, a packet corresponding to the second flow may be transmitted.

Also, if a packet corresponding to the first flow is received during the waiting time, at least one relay node may transmit a packet corresponding to the second flow in a second transmission time slot.

Preferably, the at least one relay node transmits a packet corresponding to the first flow at a first transmission offset time of a second transmission time slot when a packet corresponding to the first flow is received during the waiting time, and the second transmission A packet corresponding to the second flow may be transmitted at the second transmission offset time of the time slot.

That is, the network system 100 according to an embodiment can artificially mismatch packet transmission times to prevent transmission packet collision due to the absence of a global schedule.

2 is a diagram for explaining a wireless communication device of a network system according to an embodiment.

Referring to FIG. 2 , a wireless communication device 200 according to an embodiment may be included in each node described with reference to FIG. 1 . Therefore, among the contents described with reference to FIG. 2 , descriptions overlapping those described with reference to FIG. 1 will be omitted.

The wireless communication device 200 may include a packet receiver 210, a time slot control unit 220, and a packet transmitter 230.

The packet receiving unit 210 according to an embodiment may receive a packet corresponding to at least one flow.

The time slot control unit 220 according to an embodiment stores a network parameter piggybacked in a packet corresponding to at least one flow, and determines the priority of the flow and at least one of the stored network parameters. Based on this, it is possible to control a transmission time slot for a flow.

For example, the network parameters may include a parameter related to a transmission period and a parameter related to the number of retransmission slots per link.

The time slot control unit 220 may control the transmission offset time corresponding to the timing of transmitting the packet corresponding to the flow within the transmission time slot based on the priority of the flow.

According to one side, the time slot controller 220 receives a packet corresponding to the first flow and a packet corresponding to the second flow having a lower priority than the first flow, at the first transmission offset time of the transmission time slot. A packet corresponding to a flow can be controlled to be transmitted.

In addition, when a packet corresponding to the first flow and a packet corresponding to the second flow are received, the time slot control unit 220 determines the second transmission offset time of the transmission time slot delayed by the preset first time compared to the first transmission offset time. It is possible to control packets corresponding to the second flow to be transmitted.

According to one side, when a packet corresponding to the second flow is received, the time slot controller 220 waits for reception of a packet corresponding to the first flow until a third offset time delayed by a preset second time from the first offset time can do.

Meanwhile, the time slot controller 220 may be implemented in the form of a protocol. An example of implementing the time slot control unit 220 as a protocol will be described in more detail with reference to FIG. 3 in the following embodiment.

The packet transmission unit 230 according to an embodiment may transmit a packet corresponding to at least one flow in a controlled time slot.

3 is a diagram for explaining a configuration example of a node of a network system according to an embodiment.

Referring to FIG. 3, each node 300 constituting a network in a network system according to an embodiment includes a physical layer (PHY), a MAC layer (MAC), a net layer (NET), and an application layer (APP). can do.

According to one side, the Mac layer (MAC) may control a piggyback function (piggyback), a packet transmission/reception function (Rx-Tx), and a transmission offset time control function (TxOffset).

The piggyback function may include at least one of a function of piggybacking a network parameter to a packet corresponding to a flow and a function of storing the piggybacked network parameter in a received packet.

The packet transmission/reception function (Rx-Tx) may include a function of controlling a transmission time slot for a flow based on at least one of flow priority and stored network parameters.

The transmission offset time control function (TxOffset) may include a function of controlling the transmission offset time based on a priority for each of a plurality of flows.

4A to 4C are diagrams for explaining an example of controlling a transmission time slot in a node of a network system according to an embodiment.

Referring to FIGS. 4A to 4C, reference numeral 410 denotes a collision type of transport packets that may occur according to the absence of a global schedule, and reference numeral 420 denotes an operation example of nodes located on a transmission path corresponding to at least one flow. In the figure, reference numeral 430 shows an example of state transition according to packet transmission/reception of each node located on a transmission path.

According to reference numeral 410, the network system according to an embodiment determines its own transmission time slot at each node based on network parameters transmitted to nodes located on a transmission path corresponding to at least one flow without a global schedule. can

That is, according to the absence of a global schedule, the network system according to an embodiment collides with a common receiver (CR), collides with a low-flow receiver (LR), and collides with a low-flow sender (LS). At least one transmission collision of a collision and a common sender (CS) collision may occur.

Specifically, since each node of the network system according to an embodiment is based on half-duplex wireless communication, it is impossible to simultaneously transmit and receive packets. Accordingly, when transmission collision occurs, packet loss caused by simultaneous transmission and reception of packets in adjacent nodes and transmission delay.

에 대응되는 패킷과 우선 순위가 낮은 플로우

에 대응되는 패킷을 동시에 수신함에 따른 발생되는 전송 충돌을 의미할 수 있다. CR conflicts are high-priority flows in nodes.

Packets corresponding to and low-priority flows

This may mean a transmission collision caused by simultaneously receiving packets corresponding to .

에 대응되는 패킷을 송신할 때 인접 노드로부터 우선 순위가 낮은 플로우

에 대응되는 패킷을 수신함에 따라 발생되는 전송 충돌을 의미할 수 있으며, 이때 노드는 플로우

에 대응되는 패킷을 송신하는 과정에 있으므로 인접 노드는 플로우

에 대응되는 패킷이 송신되지 않도록 제어될 수 있다. LR collisions are high-priority flows previously received by the node.

A flow with a low priority from an adjacent node when sending a packet corresponding to

It may mean a transmission collision that occurs as a result of receiving a packet corresponding to

Since it is in the process of transmitting the packet corresponding to, the adjacent node flows

It can be controlled so that the packet corresponding to is not transmitted.

에 대응되는 패킷을 송신할 때 인접 노드로부터 우선 순위가 높은 플로우

에 대응되는 패킷을 수신함에 따른 전송 충돌을 의미할 수 있으며, 이때 노드는 플로우

에 대응되는 패킷을 송신하는 동안 인접 노드로부터 플로우

에 대응되는 패킷을 수신하지 못하도록 제어될 수 있다. LS collisions are low-priority flows previously received by the node.

A flow with a high priority from an adjacent node when sending a packet corresponding to

It may mean a transmission collision due to receiving a packet corresponding to

Flows from neighboring nodes while sending packets corresponding to

It can be controlled not to receive a packet corresponding to .

에 대응되는 패킷과 우선 순위가 낮은 플로우

에 대응되는 패킷을 동시에 송신함에 따른 발생되는 전송 충돌일 수 있다.A CS collision is a high priority flow previously received by a node.

Packets corresponding to and low-priority flows

It may be a transmission collision caused by simultaneously transmitting packets corresponding to .

According to reference numerals 420 to 430, the network system according to an embodiment may adaptively control the transmission offset time according to the first to third events.

인 경우(즉, 노드 SH로부터 패킷을 수신한 경우), 플로우

에 대응되는 패킷을 제1 전송 오프셋 시간(offset₁)에 할당할 수 있다. The first event is related to the priority of the flow, and the flow received from node u has a higher priority.

If (i.e. packet received from node SH), flow

A packet corresponding to may be allocated to the first transmission offset time (offset ₁ ).

)에 관한 것으로, 이 경우 노드 u에서 송신되는 패킷은 제2 전송 오프셋 시간(offset₂)에 할당할 수 있다.The second event occurs when the LS collision does not belong to the collision type set at the node (ie,

), in this case, the packet transmitted from the node u can be allocated to the second transmission offset time (offset ₂ ).

)에 관한 것으로, 이 경우 노드 u에서 송신되는 패킷은 제3 전송 오프셋 시간(offset₃) 이후에 처리되도록 할당할 수 있다.The third event occurs when the LS collision belongs to the collision type set (ie,

), in this case, packets transmitted from node u may be allocated to be processed after the third transmission offset time (offset ₃ ).

에 대응되는 패킷을 전송할 때 전송 충돌 및 패킷 지연이 발생하지 않도록 제어할 수 있다.Specifically, the network system flows from node u

When a packet corresponding to is transmitted, it is possible to control transmission collision and packet delay not to occur.

에 대응되는 패킷 및 플로우

에 대응되는 패킷이 동시에 수신되면 노드 u는 자체 전송을 취소하더라도 플로우

에 대응되는 패킷 은 수신을 해야한다. 이러한 선점(preemption)을 달성하기 위해, 네트워크 시스템은 플로우

에 대응되는 패킷을 전송하는 시간을 제1 전송 오프셋 시간(즉, 0ms)로 설정할 수 있다. For example, flow

Corresponding packets and flows

If the packet corresponding to is received at the same time, node u cancels its own transmission, but the flow

The packet corresponding to must be received. To achieve this preemption, the network system must

The time for transmitting the packet corresponding to may be set to the first transmission offset time (ie, 0 ms).

에 대응되는 패킷 및 플로우

에 대응되는 패킷을 동시에 수신할 수 있으며, 이 경우 목적지 노드 d_H는 캡처 효과(capture effect)에 따른 하드웨어 특성으로 인해 서로 다른 패킷의 전송 타이밍이 3ms의 차이가 있으면 서로 다른 두 패킷을 수신할 수 있다. 즉, 네트워크 시스템은 플로우

에 대응되는 패킷을 전송하는 시간을 제2 전송 오프셋 시간(즉, 3ms)로 설정할 수 있다. Also, in the network system, the destination node d _H is the flow

Corresponding packets and flows

In this case, the destination node d _H can receive two different packets if there is a difference of 3 ms between the transmission timings of different packets due to hardware characteristics according to the capture effect. there is. In other words, the network system flows

The time for transmitting the packet corresponding to may be set to the second transmission offset time (ie, 3 ms).

에 대응되는 패킷을 수신하여 송신하기 전에 플로우

에 대응되는 패킷이 수신될 가능성이 있으며, 이 경우 플로우

에 대응되는 패킷이 플로우

에 대응되는 패킷을 선점하기 위해서 노드 u는 패킷 수신을 인식 할 수 있는 최소 시간 간격 동안 플로우

에 대응되는 패킷의 송신을 보류하도록 제어될 수 있다. On the other hand, in the network system, node u is the flow

Flow before receiving and sending packets corresponding to

There is a possibility that a packet corresponding to is received, in which case the flow

The packet corresponding to flows

In order to preempt the packet corresponding to , node u flows for the minimum time interval that can recognize packet reception.

It can be controlled to hold transmission of packets corresponding to .

의 선점으로 인한 지연된 플로우

의 전송을 선점 효과(preemption effect)라 하며, 네트워크 시스템은 선점 효과를 위해 제3 전송 오프셋 시간(즉, 5ms) 동안 플로우

에 대응되는 패킷의 송신을 보류하도록 제어할 수 있다. As in this case, the flow

delayed flow due to preemption of

The transmission of is called a preemption effect, and the network system flows during the third transmission offset time (i.e., 5 ms) for the preemption effect.

It can be controlled to hold transmission of packets corresponding to .

On the other hand, each node located on the transmission path of the network system according to an embodiment is in a reception ready state (ready-to-receive, RRx), a reception state (receive, Rx), a transmission ready state (ready- State transitions may be made such as to-transmit, RTx), delay state (delay, De), and transmission state (transmit, Tx).

Specifically, node u may prepare to receive a packet by turning on a radio in a predetermined channel in an RRx state corresponding to an idle time.

)를 저장하고, 전달될 큐(queue)에 패킷을 배치할 수 있다. Next, when node u receives a packet in time slot t, it switches to the Rx state, and the network parameter piggybacked on the packet (i.e., the transmission period T _i and the number of retransmission slots per link

) and place the packet in a queue to be forwarded.

Next, in the next time slot t+1, the node u may switch to the RTx state during a transmission offset time (TxOffset) interval, which is the time from the start of the slot to the transmission of the packet within the time slot.

For example, the time slot may be 10 ms, and the transmission offset time set within the time slot may be set to a time interval smaller than 10 ms.

Also, in the RTx state, the node can check whether packets from other flows have been received.

Next, when a node in the RTx state does not receive a packet from another flow, the node switches to the Tx state and transmits the stored packet to the next node (relay node or destination node).

를 고려하여 최대

-1 회 수행될 수 있다. According to one side, if a node in the Tx state fails to transmit a packet, it can switch back to the RTx state and attempt retransmission in the next time slot, and retransmission is the number of retransmission slots.

considering the maximum

-Can be performed once.

On the other hand, in the RTx state, when a node receives a packet from another flow (i.e., flow preemption occurs), it switches to the De state. may be delayed by

That is, at the next time slot t+2, the node transitions from the De state to the RTx state and can prepare to transmit the stored packet.

That is, the network system according to one embodiment can save waste (ie, unused) time slots in a generally fixed retransmission scheduling process.

5A and 5B are diagrams illustrating an example of optimizing a third offset time in a network system according to an embodiment.

Referring to FIGS. 5A and 5B , reference numeral 510 denotes a result of measuring the time required to recognize 100,000 packets through one hop, and reference numeral 520 denotes a node u (shown in FIG. 4b). 1st hop) and node v (second hop) show the measurement result of the packet reception ratio (PRR) according to the flow.

According to reference numerals 510 to 520, it can be seen that 5 ms is sufficient for the third offset time for recognizing packet reception in the link.

에 대응되는 패킷의 늦은 전송에도 불구하고 플로우

에 대응되는 패킷보다 빠른 도착 시간 및 높은 패킷 수신 비율로 인해, 일실시예에 따른 네트워크 시스템은 최적화된 제3 전송 오프셋 시간(즉, 5ms)을 적용하여 플로우

의 선점 효과를 나타내는 것을 확인할 수 있다. i.e. flow

Flow despite late transmission of packets corresponding to

Due to the arrival time faster than the packet corresponding to and the high packet reception rate, the network system according to an embodiment applies the optimized third transmission offset time (ie, 5 ms) to flow

It can be seen that the preemptive effect of

6A to 7B are diagrams illustrating performance measurement results of a network system according to an exemplary embodiment.

6A to 7B, reference numeral 610 indicates the adaptation latency characteristics of a network system (AdaptiveHART, AH) according to an embodiment implemented in the form of a protocol and the well-known protocol WirelessHART (WH). A measurement result is shown, and reference numeral 620 shows a measurement result of schedulable ratios characteristics of the AH protocol and the WH protocol.

In addition, reference numeral 710 shows the mean absolute error (MAE) measurement result of the AH protocol and the WH protocol at the same utilization, and reference numeral 720 indicates the MAE measurement of the AH protocol and the WH protocol at maximum utilization. show the result

According to reference numerals 610 to 620, comparing the intervals of the two protocols at 90% CDF (cumulative density function), the AH protocol shows about 300% better performance than WH at 300 ms sf (superframe), and as the sf length increases, It can be seen that the performance difference increases (390% improvement at 600 ms sf).

That is, unlike the WH protocol, the AH protocol (network system according to an embodiment) can adjust network parameters at any time independently of the length of sf, so real-time adaptability can be guaranteed.

로 제어되는 플랜트

와 플로우

로 제어되는 플랜트

각각에 대하여 WH 프로토콜 대비 391% 및 742% 더 나은 제어 성능을 나타냈으며, 참조부호 720에서 AH 프로토콜은 플랜트

와 플랜트

각각에 대하여 WH 프로토콜 대비 400% 및 270% 더 나은 제어 성능을 나타낸 것을 확인할 수 있다. According to reference numerals 710 to 720, the AH protocol at 710 flows

Plant controlled by

and flow

Plant controlled by

391% and 742% better control performance than the WH protocol for each, and the AH protocol at 720

and plant

It can be seen that each shows 400% and 270% better control performance compared to the WH protocol.

That is, since the AH protocol (network system according to an embodiment) improves performance by saving wasted retransmission slots, end-to-end transmission delay can be reduced.

In addition, in the WH protocol, the frequency of dissemination intervals in which time resources are wasted increases as the flow periods decrease, so that the minimum flow period is limited to 250 ms, whereas in the AH protocol, there is no such interval, so 100 ms It is possible to select a more flexible flow period up to , showing better control performance than that achieved through the WH protocol. As a result, it can be confirmed that the AH protocol enables more frequent control in a dynamic environment.

After all, using the present invention, each node can determine its own transmission time slot without control according to a global schedule.

In addition, each node itself transmits data and can adapt to changed network parameters in real time.

In addition, transmission time can be artificially mismatched to prevent transmission packet collision due to the absence of a global schedule.

In addition, it is possible to respond more quickly when a disturbance occurs in the system through the guarantee of real-time adaptability, thereby guaranteeing high stability.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

200: wireless communication device 210: packet receiving unit
220: time slot controller 230: packet transmitter

Claims (14)

a packet receiving unit for receiving a packet corresponding to at least one flow;
A network parameter piggybacked in a packet corresponding to the at least one flow is stored, and a transmission time slot for the flow based on at least one of the priority of the flow and the stored network parameter A time slot control unit that controls (time slot) and
A packet transmission unit for transmitting a packet corresponding to the at least one flow in the controlled time slot
including,
The time slot controller,
Based on the priority of the flow, the transmission offset time corresponding to the timing of transmitting the packet corresponding to the flow within the transmission time slot is controlled, but the packet corresponding to the first flow is not received and the first flow When a packet corresponding to the second flow having a lower priority is received, the third offset time of the transmission time slot delayed by a preset second time than the first transmission offset time of the transmission time slot corresponding to the first flow control to wait for packet reception.
A wireless communication device in a network system. According to claim 1,
The network parameters are
Including parameters related to the transmission period and parameters related to the number of retransmission slots per link
A wireless communication device in a network system. delete According to claim 1,
The time slot controller,
When a packet corresponding to the first flow and a packet corresponding to the second flow are received, controlling the transmission of the packet corresponding to the first flow at the first transmission offset time
A wireless communication device in a network system. According to claim 1,
The time slot controller,
When a packet corresponding to the first flow and a packet corresponding to the second flow are received, the second flow at a second transmission offset time of the transmission time slot delayed by a predetermined first time from the first transmission offset time Controlling the transmission of packets corresponding to
A wireless communication device in a network system. delete A plurality of nodes constituting the network and
A controller for setting a transmission path corresponding to at least one flow in the network
including,
At least one relay node corresponding to the transmission path among the plurality of nodes,
Receiving a packet corresponding to the flow, storing a network parameter piggybacked in the received packet, and based on at least one of the priority of the flow and the stored network parameter to control a transmission time slot for the flow,
Based on the priority of the flow, the transmission offset time corresponding to the timing of transmitting the packet corresponding to the flow within the transmission time slot is controlled, but the packet corresponding to the first flow is not received and the first flow When a packet corresponding to a second flow having a lower priority is received, the first transmission offset time of the transmission time slot corresponds to the first flow until the third offset time of the transmission time slot delayed by a preset second time control to wait for packet reception.
network system. According to claim 7,
Each of the plurality of nodes,
Including sensors and actuators with half-duplex radio transceivers
network system. According to claim 7,
The network parameters are
Including parameters related to the transmission period and parameters related to the number of retransmission slots per link
network system. According to claim 7,
A source node corresponding to the transmission path among the plurality of nodes,
Receiving a message corresponding to the flow from the controller to generate the packet, and piggybacking the network parameter to the packet
network system. delete According to claim 7,
The at least one relay node,
When receiving a packet corresponding to the first flow and a packet corresponding to the second flow, transmitting the packet corresponding to the first flow to the next node at the first transmission offset time
network system. According to claim 7,
The at least one relay node,
When a packet corresponding to the first flow and a packet corresponding to the second flow are received, the second flow Forwarding the packet corresponding to to the next node
network system. delete

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