CN105992315B

CN105992315B - Wireless low-power consumption sensing network based on low duty cycle working mode

Info

Publication number: CN105992315B
Application number: CN201510049036.3A
Authority: CN
Inventors: 廖应成
Original assignee: WESTVALLEY DIGITAL TECHNOLOGIES Inc
Current assignee: WESTVALLEY DIGITAL TECHNOLOGIES Inc
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2020-04-10
Anticipated expiration: 2035-01-30
Also published as: CN105992315A

Abstract

Aiming at the defects of the existing wireless sensor network, the invention provides a low-power consumption wireless sensor network networking and transmission technology based on fixed network nodes and in an intermittent low-duty-ratio working mode, and realizes information relay and transmission among networking nodes on the premise of low power consumption, thereby solving the problems of long-distance automatic centralized reading of three meters of water, electricity and gas, low-power consumption long-distance acquisition of field battery-driven sensor data and the like.

Description

Wireless low-power consumption sensing network based on low duty cycle working mode

Technical Field

The invention relates to an active RFID (radio frequency identification device), a wireless sensor network and a low-power wireless communication networking technology.

Background

The existing wireless sensor networks mainly include mesh networks (mesh-net) represented by Zigbee and star networks (star-net) represented by active RFID. The mesh network represented by Zigbee is realized based on the condition that all wireless transmission nodes participating in networking are in continuous uninterrupted work, and the ZigBee also considers the dynamic change of the networking nodes of the system, so that a dynamic networking and dynamic routing mode is adopted, which inevitably wastes a large amount of network resources and affects the working efficiency of the network. Although the power consumption of each Zigbee node is only dozens of milliamperes, the Zigbee node is in a continuous working state, and a battery can only support very limited time, so that an external power supply is needed; in practical application, because the working nodes of the sensor are often fixed and invariable, the nodes for receiving and transmitting signals are very clear, and dynamic networking and dynamic routing are not needed, the places where the advantages of Zigbee dynamic networking and dynamic routing can be exerted are very limited, and thus the function is often changed into the burden of the network. Although the general active RFID adopts a low-power-consumption low-duty-cycle operation mode, networking communication cannot be realized between every two tags. With the forward advance of the information revolution of the internet of things, the need for acquiring the information of the wireless sensor is more and more urgent, and a simple non-dynamically-changed low-power-consumption wireless sensor network is urgently needed to realize the low-power-consumption acquisition and transmission of the information of the sensor.

Disclosure of Invention

Aiming at the defects of the existing wireless sensor network, the invention provides a wireless sensor network technology based on fixed network nodes and a low duty ratio working mode, thereby realizing information transmission between networking nodes on the premise of low power consumption.

All network nodes participating in networking have fixed installation positions; each node is composed of a wireless transceiver unit consisting of at least one wireless transceiver and a single chip microcomputer. Each node can be connected with a sensor or other equipment, and can realize wireless communication among the nodes, the wireless transceiver in each transceiver unit usually adopts a periodic sleep mode to listen to a signal on a pre-specified frequency channel for a moment with a low duty ratio after waking up, wherein the listening time at the moment is very short but enough to judge whether the signal which can realize wireless communication is listened to or not through the radio frequency characteristics of the received signal, including frequency, modulation mode, coding mode and the like, for example, the signal can represent one or two '0' or '1' bit signals in digital communication. Only when such a signal is heard does the wireless transceiver in the node extend the listening time until a complete command signal packet is received. The time required for the wireless transceiver to complete such initial judgment listening is very short, and is often only about 100 microseconds, so that the power is very saved. The specific working mode can be found in patent document "intelligent electronic label CN 101236611 a". Of course, under the condition of permission, part or all of the nodes participating in networking can also be supplied with power by an external power supply. Each node can be connected with a computer in a wired or wireless mode and used as a signal transmitting node to initiate a communication process. Since the time for each node to listen to the signal after waking up is very short, the sleep wake-up period of each node can be very short, such as 0.5-1 second or even shorter, while maintaining the same duty cycle, such as <1:1000, which greatly speeds up the transmission process of the signal in the whole network.

The information transmission mode among the network nodes is as follows: the information transmitting node directly transmits the information to the target node within the signal coverage range of the information transmitting node, or gradually transmits the information to the target node which is not within the signal coverage range of the information transmitting node through one or more relay nodes. The specific method comprises the following steps: the transmitting node wakes up a first relay node which monitors signals on a public wake-up channel for a moment after periodically waking up in a sleep mode by continuously broadcasting instruction signal packets outwards on the public wake-up channel (a coordination channel) within a period of time, establishes communication contact between the transmitting node and the relay node according to the requirements of the instruction signal packets, and transmits information to be transmitted to the relay node. After finishing information transmission, the transmitting node returns to a state of monitoring signals on a public channel for a moment after periodically sleeping and waking up; and the first relay node continuously sends information to the second relay node on the wake-up channel in the same way as the transmitting node, the information transmitted to the second relay node can also be received by the transmitting node, and after receiving the information, the transmitting node knows the information sent to the first relay node to be successfully received by the first relay node, otherwise, the transmitting node sends the information to the first relay node again. After the first relay node sends the information to the second relay node, the first relay node also returns to a low power consumption state of monitoring signals on the public frequency channel for a moment after the first relay node wakes up periodically. And so on until the information is delivered to the target node. Refer to the attached drawing I

The transmitting node is often an information acquisition center connected with a computer, such as an active electronic tag reader-writer; the target node and the relay node are any sensor information acquisition points; in all the sensor acquisition nodes, including the relay node and the target node, if external power supply is adopted, the nodes are normally in a state of continuously monitoring signals on a public awakening frequency channel instead of intermittently monitoring signals, and when any transmitting node transmits information to the nodes, the mode of continuously and repeatedly transmitting the same awakening instruction signal for a period of time is not needed, but only the mode of transmitting a single-packet signal is needed. This will not only speed up the information transfer but will also save power consumption of other network nodes. Thus, where conditional, sensors in the network are powered as far as possible using an external power supply.

The information sent by the transmitting node to the relay nodes comprises the address of each relay node in the whole relay link. This relay link is formed as follows:

if 200 nodes exist in a sensor information acquisition area and direct communication cannot be completely realized among all the nodes, communication among a plurality of nodes needs to be relayed to be completed. In order to find a communication link with the shortest path (the fewest relay nodes) and the best signal transmission effect (the highest received signal strength) between any two nodes, the system needs to find out other node IDs around each node and capable of directly communicating with the node, and the higher the communication quality (expressed by the signal strength when the node receives the IDs sent by the nodes) when the communication is realized with the node, the better the communication channel quality is considered. All nodes with which communication is possible, due to the occlusion of possible buildings and the complex signal transmission environment, are not necessarily distributed within a circular area centered on the node, but rather have a relatively complex shape, here represented by a simple oval, as shown in fig. two. At the same time, of all these nodes, not the nodes that are physically closer to the central node must have better signal strength or communication quality. We can use an arrow to represent the communication link between two nodes, the ID numbers of the two nodes to represent the link, and R to represent the signal strength (RSSI value when receiving ID) of the connection, which represents the quality of the link connection. A higher R value indicates a better communication link quality. E.g., IDa-IDb-R, represents the node IDa transmitting signals and the node IDb receiving signals, and R represents the signal strength at the time of communication between the two nodes.

The system will require that each of these two hundred nodes needs to broadcast an inventory command outward once, collecting the node IDs that may be collected around the node, and the corresponding signal strengths. Therefore, the communication link and the link quality between every two nodes which can directly communicate are obtained. This in effect reflects the basic communication conditions between nodes throughout the sensor network, including the effects of various buildings on communication, among other factors. As long as the node location is not changed, this condition will not change much unless significant environmental conditions affecting signal transmission occur within the area, at which time we need to re-collect such information once. The determination of the optimal communication link between all nodes in the network is based on such a fixed communication environment and the data obtained. With this knowledge, the computer will give all link connection information between any two nodes, including the shortest link connection information, and link connection information considering the link quality (received signal strength of each link of the entire link is higher than a certain value). When information needs to be transmitted between two nodes or between the reader-writer and any node in the network, the transmitting node or the reader-writer lists the address information from the first relay node to the last target node in the link in the information instruction broadcasted outwards, and data transmission is carried out according to the method. Figure three is that the transmitting end should include the ID information of all the involved link nodes in the transmitting signal packet.

Description of the drawings:

graph one, inter-node information transmission mode

FIG. two, establishment of communication links

Figure three, the link content that the transmitting node should include to transmit the signal

The specific implementation mode is as follows:

each node in the network has an ID number, a reader-writer is always used as a transmitting node, and according to the information transmission mode, the reader-writer sends an instruction for requesting each node to acquire all node IDs which can be communicated with the reader-writer and Receive Signal Strength (RSSI) one by one to the nodes which can be communicated with the reader-writer one by one through the reader-writer. And then, by the communication method, the same instruction is issued to the rest nodes one by one through the relay node, and the link communication condition information of the communication between all the nodes in the whole area is obtained.

And then searching link connection information from the reader-writer serving as the network transmitting node to all other network nodes or link connection information from any one network node to other network nodes by the computer in a head-to-tail matching mode. When the reader-writer needs to transmit information to a certain target node, all relay node IDs related in the information are used as transmitting addresses of the command signal packets according to the link information from the reader-writer to the node and are included in the command signal packets of the transmitting nodes. The information transfer is performed according to the method described above. When the reader-writer requires to collect the information of the target node, the target node transmits the reverse information according to the link information.

The same will be done when other nodes in the network need to communicate with each other.

Claims

1. A wireless low-power consumption sensor network based on a low duty cycle working mode is characterized in that the wireless low-power consumption sensor network consists of a plurality of known wireless transceiving unit nodes which can be connected with sensors or other working units, a control computer and corresponding application software; the computer and software are used for managing the whole sensor network according to application requirements; each node has a fixed installation position and can realize wireless communication with each other; the wireless transceiver in each node usually adopts a working mode of periodically sleeping, monitoring signals on a preassigned monitoring channel for a moment with low duty ratio after waking up, wherein the monitoring time at the moment is very short, but the radio frequency characteristics of the received signals are enough to judge whether the signals which can realize wireless communication with the wireless transceiver are monitored, and the wireless transceiver in the transceiver unit can prolong the monitoring time only when the signals are monitored until a complete instruction signal packet is received; each node participating in networking is powered by a battery, or can be powered by an external power supply, when the external power supply is adopted, the node is usually in a state of continuously monitoring signals on a public awakening channel instead of intermittently monitoring signals, and when any transmitting node transmits information to the node, a single-packet signal transmitting mode is adopted; each node can be connected with a computer in a wired or wireless mode, can be used as a signal transmitting node and independently and autonomously initiates a communication process; the system can transmit the information of each node initiating communication to a target node in a mode of waking up step by step and relaying step by step according to preset relay nodes and relay links; or temporarily acquiring node IDs (identity) capable of establishing communication with the surrounding of each network node and corresponding signal strength values by checking each transmitting node one by one, so as to determine the communication environment conditions among the nodes in the whole sensing network range; the information transmitting node directly transmits the information to a target node in the signal coverage range of the information transmitting node, or gradually transmits the information to the target node out of the signal coverage range of the information transmitting node through one or more relay nodes; according to the determined IDs of the transmitting node and the target node and a link node ID end-to-end matching method, all communication links with use values between all transmitting nodes and target receiving nodes are found out by a computer, wherein the communication links comprise the node ID and the connection signal strength related to each link; and finally, according to the IDs of the given signal transmitting node and the given signal receiving node, the length of each link, the link communication signal quality, the number of relay nodes with external power supplies contained in each link and application requirements, finding out one or more communication links, embedding link information into a communication signal packet between the nodes, and determining the relay node link with short path between any two nodes and good signal transmission effect.

2. The wireless low-power consumption sensing network based on the low duty cycle working mode according to claim 1, wherein the information transmission mode between the network nodes is as follows: the transmitting node continuously and repeatedly transmits an instruction signal packet to the first relay node on the appointed monitoring channel within a period of time which is not less than a sleep awakening period of the node, awakens the first relay node at the moment of monitoring signals on the appointed monitoring channel after the periodical sleep awakening, establishes communication contact between the first relay node and the second relay node and carries out information communication; after the information exchange is finished, the transmitting node returns to a state of monitoring a signal on the appointed monitoring channel for a moment after the periodic sleep wakeup; and the first relay node sends information to the transmitting node and the second relay node on the appointed monitoring frequency channel in the same way as the transmitting node, and after the first relay node sends the information to the second relay node, the first relay node also returns to a low power consumption state of monitoring signals on a public frequency channel for a moment after periodically sleeping and waking up. And so on until the information is delivered to the target node.

3. The wireless low power consumption sensing network according to claim 2, wherein each relay node receives the information from the previous transmitting node of the relay node when it continuously transmits signals to the next relay node, and determines whether the signal transmitted to the relay node by the previous transmitting node is successfully received by the relay node according to whether the signal is received.

4. The wireless low-power-consumption sensing network based on the low-duty-cycle working mode as claimed in claim 1, wherein when one node is connected with a computer as an active electronic tag reader-writer, the whole system becomes an active electronic tag system which can realize communication between tags, and all tags have a relay function, a sensor data acquisition function and an equipment control function.

5. A method for transmitting information among a plurality of wireless transceiving units by adopting a low duty ratio working mode is characterized in that all transceiving units normally adopt a working mode of periodically sleeping and monitoring signals on a preassigned public channel for a moment after waking up; the transmitting node wakes up the first relay node which is at the moment of monitoring signals on the public wakening channel after the periodic sleep wake-up in a mode of continuously and repeatedly transmitting instruction signal packets to the first relay node on the public wakening channel within a period of time which is not less than the sleep wake-up period of the node, establishes communication contact between the first relay node and the second relay node and exchanges information; after the information exchange is finished, the transmitting node returns to the state of monitoring signals on the public channel for a moment after the periodic sleep wakeup; and the first relay node sends information to the transmitting node and the second relay node on the wake-up channel in the same way as the transmitting node, and after the first relay node sends the information to the second relay node, the first relay node also returns to a low power consumption state of monitoring signals on the public wake-up channel for a moment after periodically sleeping and waking up. And so on until the information is delivered to the target node.