KR20110137616A - Method to determine priority of data transmission in wireless network - Google Patents

Abstract

PURPOSE: A method for determining the priority of data transmission in a wireless network is provided to prevent the data transmission delay according to the hop number between nodes. CONSTITUTION: The number of hops from a source node of data to a destination node of data is determined(S320). According to the number of hops, a priority factor transmitting data is determined(S330). The determined priority is stored in a frame control domain of a MAC(Medium Access Control) layer(S340). According to the priority, the transmission scheduling is operated(S350). The number of hops and entropy are reflected to the same rate and the priority factors.

Description

How to Prioritize Data Transmission in a Wireless Network {METHOD TO DETERMINE PRIORITY OF DATA TRANSMISSION IN WIRELESS NETWORK}

The disclosed technique relates to a method of prioritizing data transmission in a wireless network.

Wireless Personal Area Networks (WPANs) are networks that allow data transmission and control between devices at data rates from 250 Kbps to several Gbps over tens of meters to hundreds of meters. WPAN includes all the element technologies for interworking between sensors, such as Bluetooth, Zigbee, Ultra WideBand (UWB), and interworking between the sensor and the gateway. Wirelessly connects devices such as personal computers (PCs), mobile phones, PDAs, and home appliances, which are tens or hundreds of meters away.

IEEE 802.15 is the name of WPAN's short-range wireless communication standardization committee separated from IEEE802.11, which proceeds with the standardization of wireless local area network (WLAN). Like Bluetooth, it aims to build a wireless network of mobile communication devices, PCs, and other peripheral devices in the home. The sub-organizations include the WPAN Research Group with a maximum transmission rate of 1 Mbps and the WPAN Research Group with a maximum transmission rate of 20 Mbps.

IEEE 802.15.4 is a standard created for low rate transmission with the maximum transmission rate of 1 Mbps among WPANs. It is applied in fields such as sensor networks, smart tags, remote control, and home automation that need to minimize power consumption. do. IEEE 802.15.4 defines technologies of medium access control (MAC) and physical (PHY) layers among low rate WPANs (LR-WPANs).

An object of the present invention is to provide a method for determining the priority of data transmission in a wireless network.

In order to achieve the above technical problem, the disclosed technique is a method of determining a priority of data transmission by a node in a wireless network, the method comprising: determining a number of hops from a source node to a destination node of the data; And determining a priority factor for transmitting the data according to the number of hops.

Embodiments of the disclosed technique may have effects that include the following advantages. It should be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, since the embodiments of the disclosed technology are not meant to include all such embodiments.

According to the disclosed technology, it is possible to improve a problem of data transmission delay or transmission failure that may occur when having a large number of hops between nodes to communicate. The fields of environmental pollution monitoring and telemetry are always required to collect data on a regular basis. In this case, according to the disclosed technology, data transmission delay according to the number of hops between nodes to be communicated can be prevented, so that data can be collected constantly.

1 is a diagram for describing a wireless sensor network having a cluster tree topology.
FIG. 2 is a diagram illustrating a structure of a MAC layer frame in which a priority factor is stored according to the disclosed technology.
3 is a flowchart illustrating a method of determining priorities according to an embodiment of the disclosed technology.
4 is a flowchart illustrating a process of transmitting data in a wireless sensor network according to an embodiment of the disclosed technology.

The description of the disclosed technique is merely an example for structural or functional explanation and the scope of the disclosed technology should not be construed as being limited by the embodiments described in the text. That is, the embodiments may be variously modified and may have various forms, and thus the scope of the disclosed technology should be understood to include equivalents capable of realizing the technical idea.

On the other hand, the meaning of the terms described in the present application should be understood as follows.

The terms " first ", " second ", and the like are used to distinguish one element from another and should not be limited by these terms. For example, the first component may be named a second component, and similarly, the second component may also be named a first component.

When a component is referred to as being "connected" to another component, it should be understood that there may be other components in between, although it may be directly connected to the other component. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions describing the relationship between the components, such as "between" and "immediately between" or "neighboring to" and "directly neighboring to", should be interpreted as well.

Singular expressions should be understood to include plural expressions unless the context clearly indicates otherwise, and terms such as "include" or "have" refer to features, numbers, steps, operations, components, parts, or parts thereof described. It is to be understood that the combination is intended to be present, but not to exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

Each step may occur differently from the stated order unless the context clearly dictates the specific order. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed technology belongs, unless otherwise defined. Terms defined in commonly used dictionaries should be interpreted to be consistent with meaning in the context of the relevant art and can not be construed as having ideal or overly formal meaning unless expressly defined in the present application.

1 is a diagram for describing a wireless sensor network having a cluster tree topology. The wireless sensor network is a network composed of distributed sensors, and includes a sensor node and a sink node. The sensor node is a node including a sensor for sensing and collecting surrounding information, a processor for processing the collected information, and a small wireless transceiver for transmitting the information. The sink node is a node that sends out information collected and transmitted by the sensor node to the outside. Unlike conventional networks, wireless sensor networks are based on automated remote information collection, rather than means of communication, and are widely used in scientific, medical, military, and commercial applications such as remote monitoring systems and telemedicine. Sensors used in wireless sensor networks may include thermometers, hygrometers, cameras, microphones, and the like. The cluster tree topology is a form of peer-to-peer topology where most nodes are fully function devices (FFDs). Unlike a reduced function device (RFD) that performs data transmission only to an upper FFD, an FFD can communicate with multiple nodes of an upper node or a lower node. Any FFD among the FFDs may serve as a coordinator to provide a synchronization service with another node or another coordinator.

The wireless sensor network transmits data collected at each node between nodes (or communication terminal devices) at low data rates and low power. Each node in a wireless network with a peer-to-peer topology can communicate with any other node within range of radio waves. For example, referring to FIG. 1, when data is transmitted from node 1 (source node) to node 5 (destination node), data may be transmitted through node 1, node 2, node 3, node 4, and node 5. . In this case, the data transmitted from the node 1 to the node 5 has a larger number of hops than the data transmitted from the node 2 to the node 4 (transmitted through the node 2, the node 3, and the node 4), and thus the transmission may be delayed. In other words, if the number of hops between nodes to communicate is large, there is a high possibility that the quality of service (QoS) is not guaranteed.

The disclosed technique provides a way to ensure QoS even when the number of hops between nodes to communicate is large. According to the disclosed technology, each node constituting the wireless network determines a priority factor of data to be transmitted according to the number of hops of the data. Therefore, it is possible to prevent transmission delay that may occur when the number of hops is large. According to the disclosed technique, in FIG. 1, since the hop number 4 of data transmitted from node 1 to node 5 is greater than the hop number 2 of data transmitted from node 2 to node 4, the data transmitted from node 1 to node 5 Higher priority is given. Accordingly, node 3 may transmit data transmitted from node 1 to node 5 in advance of data transmitted from node 2 to node 4.

FIG. 2 is a diagram illustrating a structure of a MAC layer frame in which a priority factor is stored according to the disclosed technology. According to one embodiment of the disclosed technique, each node determines, at the network layer, priority according to the number of hops. The determined priority information is transmitted in the frame used in the MAC layer. As shown in FIG. 2, the MAC frame includes a MAC header (MHR) portion, a payload region (MAC Payload portion), and a frame check sequence (FCS) region (MFR portion) including a frame control region, a sequence number region, and address fields. It includes. The Frame Control area indicates the type of the transmitted frame, the format of the address field, etc. The Frame Type indicates whether the frame is one of Beacon frames, Data frames, ACK frames, and MAC Command frames. Indicates whether the network will use the security function, the Frame Pending area indicates whether there is additional data after transmitting the current data, the ACK Request area indicates whether to send an ACK message after frame delivery, and the Intra PAN area indicates the same PAN. It is determined according to whether to transmit a MAC frame or another MAC frame within the PAN. The source and destination addressing modes represent any one of three modes. At this time, the priority information may be stored in bit 7 to bit 9 and bit 12 to bit 13 (total 5 bits) which are reserved areas of the frame control area of FIG. 2. Each node performs scheduling of data to be transmitted based on the priority provided to the frame control area.

3 is a flowchart illustrating a method of determining priorities according to an embodiment of the disclosed technology. According to the disclosed technology, each node of the wireless sensor network determines the priority according to the number of hops, and determines the order of data transmission according to the determined priority, thereby solving the problem of transmission delay or transmission failure due to the increase in the number of hops. have.

In step S310, the node determines the number of hops from the source node to the destination node of the data. The number of hops from the source node to the destination node can be determined from the information of the network layer. The network layer is a layer located in the third layer among the seven layers of the OSI basic reference model, and transmits data between systems such as terminal devices through one or more communication networks. The network layer is used to identify the addresses of the systems in the network or to deliver the actual data between the systems. For example, the ZigBee network layer task defined in the ZigBee standard attaches a network identifier to the lower layer by attaching a network identifier to the lower layer, and separates the payload portion of the data from the lower layer. It can be used to establish a multi-hop routing path for data to be delivered to a distant node, to support the ability to form a new network, and to discover and manage neighboring nodes in the vicinity. Thus, the network layer can know information about peer-to-peer communication and can determine the number of hops from the source node to the destination node based on this information.

When the hop number is determined, the node determines the priority to transmit the corresponding data according to the hop number (S330). Various embodiments may exist in the method of determining the priority based on the number of hops. In one embodiment, the node may determine the priority to be proportional to the determined hop number. For example, assuming that n is assigned a priority (n is a natural number, for example, n = 5), the maximum hop number and the minimum hop number are divided into n intervals (five intervals), which are determined in step S310. Priority levels of intervals corresponding to the number of hops may be assigned to the corresponding data.

In another embodiment, the node may further determine the priority by further reflecting the network congestion degree along with the hop number determined in operation S310. In this case, step S320 in which the node is provided with network congestion is added. Network congestion may be determined from information at the network layer. The network layer is a layer that guarantees communication between peers and peers. The network layer may be information on communication between peers and peers, and creates a data queue to manage data transmitted between peers and peers. . In one example, the network congestion may be determined according to the number of occurrences of overflow in the data queue due to a delay in data transmission between a specific peer to peer. When the network congestion information is provided, the node determines a priority factor for transmitting the corresponding data according to the hop number and the network congestion in operation S330. Various implementations of determining the priority based on the hop number and the congestion may exist. For example, the node may determine the priority by reflecting the hop number and the congestion at substantially the same ratio. That is, 50% hop count. Priority can be determined by reflecting 50% congestion.

In operation S340, according to an embodiment, the node stores the determined priority in the frame control region of the medium access control (MAC) layer. The MAC layer is one of sublayers of the data link layer located in the second layer of the seven layers of the OSI basic reference model. The data link layer provides data transmission control between neighboring systems and error detection of transmission data circulating on a circuit. There are two sublayers of a logical link control (LLC) layer and a MAC layer. The data link layer converts the data received from the network layer into a unit called a frame and sends the data to the lowest level physical layer. The MAC layer is highly related to the physical layer, and is involved in sharing a physical connection of a network among various terminal devices. The MAC frame is shown in FIG. Then, in step S350, the node performs transmission scheduling according to the priority stored in the MAC frame.

4 is a flowchart illustrating a process of transmitting data in a wireless sensor network according to an embodiment of the disclosed technology.

In operation S410, the sensor node collects sensing data and generates a message to be transmitted according to the collected sensing data. For data transmission, in step S420, the sensor node performs processing in the MAC layer, and in step S430, processing in the network layer, for example, setting a quality of service level of the network transmission.

In step S440, the sensor node generates a transmission frame, and in step S450, transmits the generated transmission frame to an adjacent relay node.

In steps S460 to S490, the relay node schedules data transmission to transmit the received data toward each destination node. In step S460, the relay node determines the priority of network transmission, and in step S470, while performing scheduling of a buffer in which data to be transmitted, in step S480, according to the priority determined in step S460, the transmission having a higher priority Change the frame queue position to send the frame first. In operation S490, the relay node first transmits a frame having a high priority according to the schedule.

While the system and apparatus disclosed herein have been described with reference to the embodiments shown in the drawings for purposes of clarity of understanding, they are illustrative only and various modifications and equivalent embodiments can be made by those skilled in the art. I will understand that. Accordingly, the true scope of protection of the disclosed technology should be determined by the appended claims.

Claims (7)

What is claimed is: 1. A method of determining priority of a node transmitting data in a wireless network, the method comprising:
Determining a hop number from a source node to a destination node of the data; And
Determining a priority factor for transmitting the data according to the hop number. The method of claim 1, wherein determining the priority comprises:
Determining the priority to be proportional to the provided hop number. The method of claim 1,
And storing the determined priority in a frame control area of a medium access control (MAC) layer. The method of claim 1,
And according to the priority, performing transmission scheduling. The method of claim 1, wherein determining the priority comprises:
And determining priority according to the provided hop number and network congestion. The method of claim 5, wherein determining the priority,
Determining the priority by reflecting the hop count and the congestion at substantially the same ratio. The method of claim 5, wherein the congestion degree,
A method of determining priority that is determined by the number of occurrences of overflow in a data queue due to a peer-to-peer data transmission delay.

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