CN104349453A - Positioning method of mobile sensor node - Google Patents

Abstract

This application discloses a positioning method for mobile sensor nodes, including: A. The mobile sensor node periodically sends Bluetooth broadcast messages; B. All Bluetooth access points that receive the Bluetooth broadcast messages sent by the mobile sensor nodes broadcast to The signal strength of the message is measured to obtain the RSSI of the mobile node; C, all Bluetooth access points that receive the Bluetooth broadcast sent by the mobile sensor node report the RSSI of the mobile node to the monitoring center; D, the monitoring center The position information of the mobile sensor node is calculated according to the RSSI reported by each Bluetooth access point. The solution of the present application can significantly reduce power consumption.

Description

A Locating Method for Mobile Sensor Nodes

technical field

The present application relates to short-distance wireless communication technology, and in particular to a positioning method for mobile sensor nodes.

Background technique

With the development of wireless communication technology, especially the advancement of digital communication technology, the cost performance of wireless products has become more reasonable. Therefore, monitoring, tracking and positioning using wireless technology have become a reality. Common wireless tracking and positioning devices currently on the market are usually based on technologies such as Global Positioning System (GPS), Global System for Mobile Communications (GSM), and Wideband Code Division Multiple Access (WCDMA). Among them, GPS is currently the most successful positioning technology, but for wireless tracking and positioning in small areas, the accuracy of GPS is far from meeting the requirements.

Bluetooth technology is a radio technology that supports short-distance communication (generally within 10m) of devices. It works in the globally common 2.4GHz ISM (industrial, scientific, medical) frequency band, adopts fast frequency hopping and short packet technology, and supports point-to-point and point-to-point Multi-point communication, using time-division duplex transmission scheme to achieve full-duplex transmission. The characteristics of Bluetooth technology can be summarized as follows:

worldwide use;

Can transmit voice and data at the same time;

A temporary peer-to-peer connection can be established;

Has good anti-interference ability;

The Bluetooth module is small in size and can be easily integrated into various devices;

low power consumption;

Open interface standards.

So far, the Bluetooth protocol has launched six versions: Bluetooth V1.1/1.2/2.0/2.1/3.0/4.0. The latest Bluetooth 4.0 version combines three core Bluetooth technologies, including traditional Bluetooth technology, Bluetooth high-speed technology and Bluetooth Low Energy (BLE, Bluetooth Low Energy) technology into one. The three technical specifications can be used independently or simultaneously. Among them, the low power consumption technology can be said to be a major breakthrough of Bluetooth 4.0 version, with extremely low operating and standby power consumption, and Bluetooth devices can even work continuously for several years with a button battery. At the same time, it also has many features such as low cost, cross-vendor interoperability, low latency of 3 milliseconds, ultra-long distance over 100 meters, and AES-128 encryption. It can be used for pedometers, heart rate monitors, smart meters, sensor IoT, etc. It has a wide range of applications in many fields.

The advantages of Bluetooth technology provide conditions for its practical application in wireless tracking and positioning in small areas. The mobile sensor node using Bluetooth technology has the characteristics of advanced technology, small size, low power consumption, and low cost. Moreover, the monitored object is allowed to move within a certain range during the monitoring process. Therefore, using Bluetooth technology for special occasions, Such as hospitals, mines, workshops, prisons and other regional occasions for real-time positioning and tracking of personnel, and in the event of an accident, the location of the personnel is located, which plays a role in timely handling of accidents, taking emergency measures, and reducing the degree of harm. very important role.

Existing Bluetooth positioning systems are mainly based on traditional Bluetooth technology. For example, the Chinese patent "Bluetooth wireless tracking and positioning system" with application number 200520110589.7 discloses a technical solution: the position information of the monitored slave device needs to be reported by the slave device to the corresponding master access point device, and the master access point device must The tracking and positioning of the slave devices within its control range must establish a wireless link with the slave devices to complete the collection of slave device location information. The disadvantages of this scheme are:

1. The slave device needs to establish and maintain a connection with the master access point device, which consumes a lot of power consumption;

2. The slave device can only maintain connection with one master access point device at the same time, and cannot achieve multi-point positioning;

3. The moving slave device is very likely to switch between multiple master access point devices in a short period of time, resulting in frequent connection establishment and disconnection.

The technical solution disclosed in the Chinese patent "Bluetooth Underground Wireless Positioning System" with the application number 200710078442.8 is: use the query command of the Bluetooth base station to obtain the signal strength of the Bluetooth mobile station. The monitoring host is used to locate the Bluetooth mobile station. This solution only requires the Bluetooth base station to query the Bluetooth mobile station without establishing a connection with it, and does not need to establish and disconnect frequently during the device movement. At the same time, because a Bluetooth mobile station can accept inquiries from multiple Bluetooth base stations , the monitoring host can integrate the Bluetooth mobile station information reported by multiple Bluetooth base stations to locate it, so as to realize multi-point positioning and improve the positioning accuracy. However, this solution also has the following two problems:

1. Using the query command of the Bluetooth base station to obtain the signal strength of the Bluetooth mobile station means that the Bluetooth mobile station needs to monitor the query scanning channel, and the power consumption of the mobile station is large;

2. The Bluetooth mobile station must respond to the inquiry command of each Bluetooth base station it monitors. When the mobile station is located within the coverage of multiple Bluetooth base stations, the power consumption of the mobile station will increase greatly.

Contents of the invention

This application provides a positioning method for mobile sensor nodes, which can significantly reduce power consumption.

A positioning method for a mobile sensor node provided in an embodiment of the present application includes:

A. Mobile sensor nodes periodically send Bluetooth broadcast messages;

B. All Bluetooth access points that receive the Bluetooth broadcast message sent by the mobile sensor node obtain the RSSI of the mobile node by measuring the signal strength of the Bluetooth broadcast message;

C. All Bluetooth access points that receive the Bluetooth broadcast sent by the mobile sensor node report the RSSI of the mobile node to the monitoring center;

D. The monitoring center calculates the location information of the mobile sensor node according to the RSSI reported by each Bluetooth access point.

Preferably, the Bluetooth broadcast message is a non-connection broadcast message or a connection broadcast message.

Preferably, when the mobile sensor node is in a disconnected state and there is no other business data to interact with the Bluetooth access point, the Bluetooth broadcast message is a disconnected broadcast message.

Preferably, when the mobile sensor node is in a non-connected state and there is other business data to be exchanged with the Bluetooth access point, the Bluetooth broadcast message is a connection broadcast message.

Preferably, the mobile sensor node is in a connected state, and the Bluetooth broadcast message is a non-connected broadcast message.

Preferably, the cycle for the mobile sensor node to send the Bluetooth broadcast message is determined according to the mobile sensor node's moving speed and positioning accuracy requirements. The faster the moving speed and the higher the positioning accuracy, the shorter the broadcast cycle, and vice versa, the longer the broadcast cycle.

It can be seen from the above technical solutions that the mobile sensor nodes periodically send broadcast messages on the broadcast channel, and the Bluetooth access point scans the broadcast channel to obtain the signal strength of the mobile sensor node and reports it to the monitoring center. The mobile sensor node information reported by the entry point is used to locate it. This application scheme utilizes the slave device broadcast feature introduced by low-power Bluetooth technology, and uses broadcast messages to locate the mobile sensor node. The mobile sensor node does not need to maintain a Bluetooth connection, and the Bluetooth access point does not need to monitor the query scanning channel, thereby reducing the mobile sensor. Power consumption of nodes and Bluetooth access points.

Description of drawings

Fig. 1 is a schematic diagram of the network topology of the bluetooth communication system;

FIG. 2 is a schematic flowchart of a positioning method for a mobile sensor node provided in an embodiment of the present application.

Detailed ways

The technical solution of this application is based on the low-power bluetooth technology. Bluetooth low energy technology is usually based on a master/slave mechanism, that is, a master device is connected to multiple slave devices. A device can be a master or a slave, but it cannot be both a master and a slave. The allowable communication frequency of the slave device is controlled by the master device, and the slave device will communicate with it only when the master device requires it. In addition, a new feature of Bluetooth low energy technology is the "broadcast" function of the slave device. A slave device can use this method to announce that it has information to send to the master device.

The positioning method of the mobile sensor node provided by this application is designed with the idea of: using the broadcast feature of the slave device introduced by the low-power Bluetooth technology, the mobile sensor node periodically sends broadcast messages on the broadcast channel, and the Bluetooth access point scans the broadcast The channel obtains the signal strength of the mobile sensor node and reports it to the monitoring center, and the monitoring center locates it based on the information of the mobile sensor node reported by multiple Bluetooth access points.

In order to make the technical principles, features and technical effects of the technical solution of the present application clearer, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

The low-power bluetooth technology is based on a star topology. As shown in Figure 1, the monitoring center connects multiple master devices (Bluetooth access points) through a LAN, and each master device has a certain communication coverage. There are one or more slave devices (mobile sensor nodes) within communication range. Taking the network topology shown in Figure 1 as an example, the flow of the positioning method for mobile sensor nodes provided in the embodiment of the present application is shown in Figure 2, including the following steps:

Step 201: The mobile sensor node periodically sends a Bluetooth broadcast message, which can be a non-connection broadcast message or a connection broadcast message, and the specific principles are as follows:

When the mobile sensor node is in a disconnected state and there is no other business data to interact with the Bluetooth access point, send a disconnected broadcast message;

When the mobile sensor node is in a non-connected state and there are other business data to be interacted with the Bluetooth access point, send a connection broadcast message;

When the mobile sensor node is in the connected state, it sends a non-connected broadcast message.

The cycle of broadcasting messages can be determined according to the moving speed of mobile sensor nodes and the requirements of positioning accuracy; in principle, the faster the moving speed of mobile sensor nodes and the higher the positioning accuracy, the shorter the broadcast cycle. The simpler method is to set them in different Various speed thresholds are set under the positioning accuracy of the mobile node, and the broadcast period is determined according to the moving speed range of the mobile node. Of course, more complex calculation formulas can be designed, which is not specifically limited in this application.

Step 202 All the Bluetooth access points that receive the Bluetooth broadcast message sent by the mobile sensor node obtain the received signal strength indication (RSSI, Received Signal Strength Indication) of the mobile node by measuring the signal strength of the Bluetooth broadcast message.

Step 203: All Bluetooth access points that receive the Bluetooth broadcast from the mobile sensor node report the RSSI of the mobile node to the monitoring center.

Step 204: The monitoring center calculates the location information of the mobile sensor node according to the RSSI reported by each Bluetooth access point.

The present application does not limit the specific algorithm used to calculate the location information of the mobile sensor node, and any positioning algorithm in the prior art that can perform positioning based on RSSI strength can be applied to the solution of this application.

The beneficial effects of the technical solution of the present application mainly include:

The mobile sensor nodes periodically send broadcasts, and the Bluetooth access point scans the broadcast channel to obtain the signal strength of the mobile sensor nodes, which reduces the power consumption of the mobile nodes. Since the signal strength is obtained by measuring the broadcast signal of the mobile sensor node through the Bluetooth access point, the mobile node only needs to send a broadcast message to enable multiple access points to obtain their signal strength, further reducing the mobile node's signal strength. power consumption.

The above descriptions are only preferred embodiments of the application, and are not intended to limit the scope of protection of the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the technical solutions of the application are It should be included within the protection scope of this application.

Claims (6)

1. A positioning method for a mobile sensor node, characterized in that, comprising: A. Mobile sensor nodes periodically send Bluetooth broadcast messages; B. All Bluetooth access points that receive the Bluetooth broadcast message sent by the mobile sensor node obtain the RSSI of the mobile node by measuring the signal strength of the Bluetooth broadcast message; C. All Bluetooth access points that receive the Bluetooth broadcast sent by the mobile sensor node report the RSSI of the mobile node to the monitoring center; D. The monitoring center calculates the location information of the mobile sensor node according to the RSSI reported by each Bluetooth access point. 2. The positioning method according to claim 1, wherein the Bluetooth broadcast message is a non-connection broadcast message or a connection broadcast message. 3. The positioning method according to claim 2, wherein when the mobile sensor node is in a disconnected state and there is no other business data to interact with the Bluetooth access point, the Bluetooth broadcast message is a disconnected broadcast message . 4. The positioning method according to claim 2, wherein when the mobile sensor node is in a non-connected state and there are other business data to be interacted with the Bluetooth access point, the Bluetooth broadcast message is a connection broadcast message. 5. The positioning method according to claim 2, wherein the mobile sensor node is in a connected state, and the Bluetooth broadcast message is a non-connection broadcast message. 6. positioning method according to claim 1, is characterized in that, the cycle that mobile sensor node sends bluetooth broadcast message is determined according to the moving speed of mobile sensor node and the requirement of positioning accuracy, the faster moving speed, the higher the positioning accuracy then broadcast The shorter the cycle, the longer the broadcast cycle.