CN108235427B - A method to measure Tof and Tdoa - Google Patents

Abstract

The present invention relates to a method for measuring Tof and Tdoa, which initiates a request-response-re-response communication between a communication master anchor node and a label node, and performs the following operations in the communication process: label node sets or measures to receive request data packets to The time of sending the response data packet, each sub-anchor node measuring the time from receiving the request data packet sent by the communication main anchor node to receiving the response data packet sent by the label node, each sub-anchor node measuring and receiving the request sent by the communication main anchor node The time from the data packet to the time when the communication master anchor node sends and then responds to the request data packet. Finally, calculate the propagation time from the primary anchor node of the communication to the label node, the propagation time of the response data packet from the label node to the secondary anchor node, and the time difference between the primary anchor node sending two request packets to the secondary anchor node. The invention has the advantages of fast positioning speed, low positioning cost and high positioning accuracy, and is especially suitable for positioning equipment in wireless networks in indoor positioning systems.

Description

A method to measure Tof and Tdoa

technical field

The invention relates to a method for measuring Tof and Tdoa, in particular to a measuring method which provides a technical basis for node positioning of wireless sensor networks or node positioning of wireless access equipment, and belongs to the technical field of signal detection.

Background technique

In daily life and production processes, it is often necessary to measure the geographic location information of wireless devices. The more accurate the instantaneous phase measured is, the better the application effect is. The ToF ranging method is a two-way ranging technology. It mainly uses the flight time of the signal to and fro between two asynchronous transceivers to measure the distance between nodes. The positioning of a node requires multiple Tof measurements to achieve the data required for positioning. . Different from TOA, the traditional TDOA (Time Difference of Arrival) determines the position of the mobile station by detecting the time difference between the arrival of the signal to the two base stations, rather than the absolute time of arrival. During the positioning process, the positioned node only needs to send the information once to complete the positioning. , but this also increases the clock synchronization requirements for the device. The patent 201710256773 has been applied for, mainly by using the communication master anchor node to measure the time from the communication master anchor node to the label, it is necessary to obtain data from the three nodes of the communication master anchor node, the label and the sub-anchor node. Compared with the traditional Tof technology, Although the positioning time is shortened, the accuracy of the measurement will be reduced. Therefore, a measurement method that can not only shorten the positioning time but also ensure the measurement accuracy is required.

SUMMARY OF THE INVENTION

The purpose of the present invention is: in view of the defects existing in the prior art, a method for measuring Tof and Tdoa is proposed. In comparison, it can not only shorten the positioning time, but also reduce the system redundancy; at the same time, it can also reduce the error of the measurement data and ensure the measurement accuracy.

In order to achieve the above objects, the present invention provides a method for measuring Tof and Tdoa. The positioning system includes a label node to be located and at least three anchor nodes, and the anchor nodes include at least one communication master anchor node and at least two secondary anchor nodes. An anchor node, the communication main anchor node performs two-way communication with the label node, and the sub-anchor node is used to monitor the communication main anchor node and the label node, including the following steps:

Step 1), select an anchor node that is connected to the label node as the main communication anchor node, and the other anchor nodes are used as secondary anchor nodes to initiate a request-response-re-response communication between the communication main anchor node and the label node:

Step 1.1), the communication master anchor node sends a request packet;

Step 1.2), the label node and the secondary anchor node receive the request data packet sent by the communication main anchor node;

Step 1.3), the label node sends a response packet;

Step 1.4), the communication main anchor node and the sub-anchor node receive the response data packet sent by the label node;

Step 1.5), the communication master anchor node sends out a re-response request data packet;

Step 1.6), the label node and the secondary anchor node receive the re-response request data packet sent by the communication main anchor node; the re-response request data packet sent by the communication main anchor node is used as the request data packet of the next round of positioning communication, and then responds to the request The data packet contains the label address of the next round of positioning;

Step 2), in the process of the request-response-re-response communication between the communication master anchor node and the label node, the label node is responsible for the time from receiving the request packet to sending the response packet and sending the response packet to receiving from the communication master anchor. The time of the node's re-response request packet is set or measured; the label node places the time from receiving the request packet to sending the response packet in the response packet, so as to facilitate the calculation of the secondary anchor node; when receiving the request When the time from the data packet to sending the response data packet is the set value, the set value may not be transmitted through the network; the communication master anchor node sets or measures the time from receiving the response data packet to sending the re-response data packet, the said The communication master anchor node places the time from receiving the response data packet to sending the re-response data packet in the re-response data packet to facilitate the calculation of the secondary anchor node; the time from receiving the response data packet to sending the re-response data packet is set When the value is set, the set value can not be transmitted through the network;

Step 3), in the process of request-response-re-response communication between the communication main anchor node and the label node, each sub-anchor node receives the request data packet sent by the communication main anchor node to the response data packet sent by the label node. The time from receiving the request data packet sent by the communication master anchor node to the time of receiving the re-response request data packet sent by the communication master anchor node is measured; the secondary anchor node only receives twice the communication master anchor node during the communication process. The request data packet and the response data packet sent by the label node, measure and record the time from receiving the two request data packets sent by the communication master anchor node to receiving the response data packet sent by the label node;

Step 4), according to the geographical coordinates of each anchor node or the distance between each anchor node, calculate the propagation time of the communication main anchor node to the label node and the propagation time of the response data packet from the label to each sub-anchor node;

The calculation method of the propagation time from the communication master anchor node to the label node is as follows:

The propagation time from the communication master anchor node to the label node = (the time from the secondary anchor node receiving the request packet sent by the communication master anchor node to the time of receiving the re-response request packet sent by the communication master anchor node - the label node receiving the request packet to sending the response The time of the data packet - the time from the communication master anchor node receiving the response data packet to sending the re-response data packet)/2;

For each sub-anchor node, the calculation method of the propagation time from the label node to the sub-anchor node is as follows:

Step 4.1), according to the geographic coordinates of the communication main anchor node, the sub-anchor node or the distance between the communication main anchor node and the sub-anchor node, calculate the propagation time from the sub-anchor node to the communication main anchor node;

Step 4.2), the propagation time from the label node to the secondary anchor node = the time from when the secondary anchor node receives the request data packet sent by the communication main anchor node to the time it receives the response data packet sent by the label node + the propagation time from the secondary anchor node to the communication main anchor node - The propagation time from the communication master anchor node to the label node - the time from the label node receiving the request data packet to sending the response data packet;

At the same time, the propagation time difference between the response data packet sent by the label node and any two anchor nodes is generated; the calculation method is as follows:

For the two anchor nodes involved, the difference is performed after obtaining the propagation time from the label node to it respectively.

Preferably, the following methods are adopted to solve the clock stability problem of each anchor node and label node:

The communication master anchor node periodically sends a broadcast data packet or sends a broadcast data packet containing the sending time at least twice, and the label node or the secondary anchor node performs the following calculation according to the arrival time of the two received broadcast data packets:

Frequency ratio factor = the arrival time difference of two broadcast packets received by the label node or the secondary anchor node/the sending time difference of the main anchor node of the communication extracted by the label node or the secondary anchor node from the two broadcast data packets; if the label node receives it The time from the request data packet to the sending of the response data packet is set, and the set data is multiplied by the frequency ratio factor for correction;

If the label node measures the time from receiving the request data packet to sending the response data packet, it divides the measured data by the frequency ratio factor for correction;

When measuring the time parameter, the secondary anchor node divides the measured data by the frequency ratio factor for correction.

Preferably, the measured travel times are corrected for air refractive index, radio wave free space attenuation, circuit delay and antenna delay.

Compared with the prior art, the present invention adopts the above technical scheme, and has the following technical effects:

1) The traditional Tof technology needs to perform multiple Tof measurements when performing node positioning, which is cumbersome and redundant, and the method adopted in the present invention utilizes geographic information, and only needs to send a request packet once at the communication main anchor node, and the label node sends a response once Data packets, the communication master anchor node can complete the collection and calculation of the propagation time between all anchor nodes and label nodes when the communication master node sends the data packet again and responds to the request packet, which greatly shortens the positioning time.

2) The traditional Tdoa technology requires strict clock synchronization during node positioning. The method adopted by the present invention solves the problem of clock synchronization between the label node and the communication master anchor node by using the method of sending data packets one more time. For the sub-anchor node, the clock synchronization of the sub-anchor node can be solved by using the fixed positions of the known communication main and sub-anchor nodes and the clock frequency ratio of the communication main-anchor node. This method does not require strict clock synchronization. can be measured more accurately.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of measuring Tof and Tdoa for one tag using the present invention.

FIG. 2 is a schematic diagram of measuring Tof and Tdoa on two label nodes using the present invention.

Detailed ways

This embodiment provides a method for measuring Tof and Tdoa in a positioning system, wherein the positioning system includes a label node to be positioned and at least three anchor nodes. The anchor node includes at least one communication master anchor node that keeps connection with the label node and at least two secondary anchor nodes. The main communication anchor node performs two-way communication with the label node, and the sub-anchor node plays a monitoring role in the system to monitor the communication main anchor node and the label node.

Fig. 1 is the schematic diagram that adopts the present invention to carry out Tof and Tdoa measurement to 1 label node, concrete steps are as follows:

The communication master anchor node initiates a request-response-re-response communication with the tag according to the tag address, that is, the communication master anchor node sends a request packet 1, and the label node and each sub-anchor node receive the request packet 1 sent by the communication master anchor node. Second, the label node sends a response data packet 2; again, the communication master anchor node and each sub-anchor node receive the response data packet 2 sent by the label node; after that, the communication master node sends a re-response request data packet 3, which re-responds to the request data The packet 3 is also used as the request data packet for the next round of positioning communication; finally, the label node and each secondary node receive the re-response request data packet 3 sent by the communication master node.

In the process of request-response-re-response communication between the communication master anchor node and the label node, firstly, the time (T reply1) from the label node receiving the request packet 1 to sending the response packet 2 (T _reply1 ) and the communication master anchor node receiving from the label The time from the node's response data packet to sending the re-response request data packet (T _reply2 ) is measured. If T _reply1 and T _reply2 are set values, these two values may not be transmitted through the network.

For each secondary anchor node i receives the request data packet sent by the communication master anchor node to the time (T _di ) from receiving the response data packet 2 sent by the label node, and each secondary anchor node i receives the request data sent by the communication master anchor node. The time (Ti) from the packet to receiving the re-response request data packet 3 sent by the communication master anchor node (Ti) is measured.

i represents the i-th sub-anchor node participating in localization, i≥2. Figure 1 only draws one sub-anchor node, and other anchor nodes are processed in the same way as sub-anchor node i.

The calculation method of the propagation time from the communication master anchor node to the label node is as follows:

Propagation time from the communication master anchor node to the label node (T _p ) = (the time from when the secondary anchor node i receives the request packet 1 sent by the communication master anchor node to the time it receives the re-response request packet 3 sent by the communication master anchor node (Ti) - The time from the label node receiving the request packet 1 to sending the response data packet 2 (T _reply1 ) - The time from the communication master anchor node receiving the response data packet from the label node to sending the second request data packet ( _Treply2 ))/2.

The time between the label node receiving the request packet 1 and sending the response packet 2 (T _reply1 ) and the time from the label node sending the response packet 2 to receiving the re-response request packet 3 from the communication master anchor node (T _round2 ) are determined by the label The node performs measurement. When the time between the tag receiving the request packet and the sending of the response packet and the time between the communication master node receiving the response packet and sending the re-response packet are both set values, these two values can be omitted. network delivery.

The calculation method of the propagation time from the sub-anchor node i to the label node is as follows:

Since the secondary anchor node can only receive two request packets (request packet 1 and re-response request packet 3, respectively) sent by the communication master anchor node and response packet 2 sent by the label node in the whole process of communication, the measurement And record the time from receiving the aforementioned two request data packets sent by the communication master anchor node to receiving the response data packet 2 sent by the label node. The sum of this time and the propagation time converted from the distance between the communication primary anchor node and the secondary anchor node represents the time from the communication primary anchor node sending the request packet to the secondary node receiving the response packet sent by the label node, and the communication primary anchor node sending the request packet to the secondary node. The time from the request data packet to the secondary anchor node receiving the response data packet sent by the label node can be further decomposed into the propagation time from the communication main anchor node to the label node, the time from the label node receiving the request data packet to sending the response data packet, and the time from the label node to the secondary node. The propagation time of the anchor node. The propagation time from the communication main anchor node to the label node has been calculated by the sub-anchor node. The time from the label node receiving the request packet to sending the response packet is a set time (the time is obtained through measurement), so the label node arrives at The propagation time of the sub-anchor node can also be directly obtained by solving.

Since the positions of the main communication anchor node and the sub-anchor node i are fixed, the distance between the sub-anchor node i and the main communication anchor node can be calculated according to the geographic coordinates of the main communication anchor node and the sub-anchor node i or the distance between the anchor nodes. propagation time. Then the propagation time from the secondary anchor node i to the label node (T _Pi ) = the time from when the secondary anchor node i receives the request packet sent by the communication master anchor node to the time it receives the response packet sent by the label node (Tdi) + the communication master anchor node The propagation time (T _Ci ) converted from the distance between the secondary anchor node i - the propagation time from the communication main anchor node to the label node (T _p ) - the time from the label node receiving the request packet to sending the response data packet (T _reply1 ).

Among them, the propagation time (T _p ) from the communication main anchor node to the label node is calculated and obtained by the secondary anchor node; the time from the label node receiving the request data packet to the sending of the response data packet (T _reply1 ) is measured or set by the label node; The distance-converted propagation time (T _Ci ) between the communication main anchor node and the sub-anchor node i is obtained by calculating the geographic coordinates of the communication main anchor node and sub-anchor node i or the distance between the communication main anchor node and sub-anchor node i; The time (T _di ) from the time when the secondary anchor node i receives the request data packet sent by the communication master anchor node to the time when it receives the response data packet sent by the label node is measured by the secondary anchor node i.

The time between the label node receiving the request data packet and sending the response data packet (T _reply1 ) and the time from the communication master anchor node receiving the response data packet from the label node to sending the re-response request data packet (T _reply2 ) can be a mutually agreed time , or the label node places the time difference in the response data packet according to its actual time difference between sending and receiving, so as to facilitate the relevant calculation of the secondary anchor node.

From the propagation time between the anchor node and the label node obtained in the above steps, select the propagation time from the anchor node of any two anchor nodes to the label node, and perform a subtraction operation to generate the label node to any two anchor nodes. propagation time difference.

Obtain the coordinates of the anchor node and the statistical information of the propagation time of the signal from the label node to the anchor node and/or the propagation time difference from the label node to the anchor node, and use TOF, TDOA, TOF/TDOA hybrid algorithm to determine the final position of the label estimated value.

In the communication, the label node has a label address that indicates its unique identity. The communication master anchor node contains the label address, a group of label addresses or broadcast addresses in the request data packet 1 or 3 sent by the label node according to the request data packet 1 or 3. 3 contains the tag address, a group of tag addresses or broadcast addresses to confirm whether and when to respond, that is, to confirm a single tag node in the system or a multi-tag node in the system through the tag address.

For a label node or a sub-anchor node, its clock stability can be solved by using the frequency ratio. The method is as follows:

The communication master anchor node periodically sends a broadcast data packet or sends a broadcast data packet containing the sending time at least twice, and the tag or secondary anchor node calculates the following according to the arrival time of the two received broadcast data packets:

Frequency ratio factor=arrival time difference of two broadcast data packets received by the label node or secondary anchor node/transmission time difference of the communication master anchor node extracted by the label or secondary anchor node from the two broadcast data packets.

If the label node sets the time from receiving the request data packet to sending the response data packet, it is corrected by multiplying the frequency ratio factor on the basis of the set data;

If the label node measures the time from receiving the request data packet to sending the response data packet, it divides the frequency ratio factor on the basis of the measurement data for correction;

When the secondary anchor node measures the time parameter, it divides the frequency ratio factor on the basis of the measurement data for correction.

Corrective actions can be performed on the server.

The preferred solution is that each module uses a high-precision clock without calculating the frequency ratio.

Since the output radio frequency signal generated by the radio frequency chip will enter the medium through the amplifier circuit and antenna, and the radio frequency signal received from the medium will enter the radio frequency chip after passing through the antenna and conditioning circuit, and the propagation of the signal in the circuit and the antenna takes time, and the measurement results Correcting for circuit delay and antenna delay results in more accurate measurements.

FIG. 2 is a schematic diagram of measuring Tof and Tdoa on two label nodes using the present invention, and the specific process will not be repeated.

The traditional Tof-based positioning technology has the disadvantage of long positioning time due to the use of multiple ranging, and the traditional Tdoa-based positioning technology has the disadvantage of high positioning cost due to the need for a high-precision clock.

In addition to the above-described embodiments, the present invention may also have other embodiments. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (3)

1. A method for measuring Tof and Tdoa, the positioning system includes a label node that needs to be located and at least three anchor nodes, the anchor nodes include at least one communication main anchor node and at least two secondary anchor nodes, the communication main anchor node. The anchor node performs two-way communication with the label node, and the secondary anchor node is used to monitor the communication main anchor node and the label node, which is characterized in that it includes the following steps: Step 1), select an anchor node that maintains connection with the label node as the main communication anchor node, and the other anchor nodes are used as sub-anchor nodes to initiate a request-response-re-response communication between the communication main anchor node and the label node: Step 1.1), the communication master anchor node sends a request packet; Step 1.2), the label node and the secondary anchor node receive the request data packet sent by the communication primary anchor node; Step 1.3), the label node sends a response packet; Step 1.4), the communication main anchor node and the sub-anchor node receive the response data packet sent by the label node; Step 1.5), the communication master anchor node sends a re-response request data packet; Step 1.6), the label node and the secondary anchor node receive the re-response request data packet sent by the communication master anchor node; the re-response request data packet sent by the communication master anchor node is used as the request data packet for the next round of positioning communication, and then responds to the request The data packet contains the label address of the next round of positioning; Step 2), in the process of the request-response-re-response communication between the communication master anchor node and the label node, the label node determines the time from receiving the request data packet to sending the response data packet and the time from sending the response data packet to receiving from the communication master anchor. The time of the node's re-response request packet is set or measured; the label node places the time from receiving the request packet to sending the response packet in the response packet, so as to facilitate the calculation of the secondary anchor node; when receiving the request When the time from the data packet to sending the response data packet is the set value, the set value may not be transmitted through the network; the communication master anchor node sets or measures the time from receiving the response data packet to sending the re-response data packet, the said The communication master anchor node places the time from receiving the response data packet to sending the re-response data packet in the re-response data packet to facilitate the calculation of the secondary anchor node; the time from receiving the response data packet to sending the re-response data packet is set When the value is set, the set value can not be transmitted through the network; Step 3), in the process of request-response-re-response communication between the communication master anchor node and the label node, each sub-anchor node receives the request data packet sent by the communication master anchor node to the response data packet sent by the label node. The time from receiving the request data packet sent by the communication master anchor node to the time of receiving the re-response request data packet sent by the communication master anchor node is measured; the secondary anchor node only receives twice the communication master anchor node during the communication process. The request data packet and the response data packet sent by the label node, measure and record the time from receiving the two request data packets sent by the communication master anchor node to receiving the response data packet sent by the label node; Step 4), according to the geographic coordinates of each anchor node or the distance between each anchor node, calculate the propagation time of the communication main anchor node to the label node and the propagation time of the response data packet from the label to each sub-anchor node; The calculation method of the propagation time from the communication master anchor node to the label node is as follows: The propagation time from the communication master anchor node to the label node = (the time from the secondary anchor node receiving the request packet sent by the communication master anchor node to receiving the re-response request packet sent by the communication master anchor node - the label node receiving the request packet to sending the response The time of the data packet - the time from the communication master anchor node receiving the response data packet to sending the response data packet) / 2; Step 4.1), according to the geographic coordinates of the main communication anchor node and the sub-anchor node or the distance between the main communication anchor node and the sub-anchor node, calculate the propagation time from the sub-anchor node to the main communication anchor node; Step 4.2), the propagation time from the label node to the sub-anchor node = the time from when the sub-anchor node receives the request packet sent by the communication main anchor node to the time when it receives the response data packet sent by the label node + the propagation time from the sub-anchor node to the communication main anchor node - The propagation time from the communication master anchor node to the label node - the time from the label node receiving the request data packet to sending the response data packet; At the same time, the propagation time difference between the response data packet sent by the label node and any two anchor nodes is generated; the calculation method is as follows: For the two anchor nodes involved, the difference is performed after obtaining the propagation time from the label node to it respectively. 2. the method for measuring Tof and Tdoa according to claim 1, is characterized in that: adopt the following method to solve the clock stability problem of each anchor node and label node: The communication master anchor node periodically sends a broadcast data packet or sends a broadcast data packet containing the sending time at least twice, and the label node or the secondary anchor node performs the following calculation according to the arrival time of the two received broadcast data packets: Frequency ratio factor = the arrival time difference of two broadcast packets received by the label node or the secondary anchor node / the transmission time difference of the main anchor node of the communication extracted by the label node or the secondary anchor node from the two broadcast packets; If the label node sets the time from receiving the request data packet to sending the response data packet, it is corrected by multiplying the frequency ratio factor on the basis of the set data; If the label node measures the time from receiving the request data packet to sending the response data packet, it divides the measured data by the frequency ratio factor for correction; When measuring the time parameter, the secondary anchor node divides the measured data by the frequency ratio factor for correction. 3. The method for measuring Tof and Tdoa according to claim 1, wherein the measured propagation time is corrected for air refractive index, radio wave free space attenuation, circuit delay and antenna delay.

Images