A method for increasing the number of terminal accesses in a beacon broadcast UWB ranging system

Abstract

The present invention discloses a method for increasing the terminal access amount of a beacon broadcast type UWB ranging system, comprising the following steps: setting a UWB ranging system; counting the current number of terminals; calculating the current broadcast period and performing dynamic frequency modulation; setting a random delay; setting a random preamble; broadcasting with a fixed preamble; receiving a signal and judging whether to perform group retransmission according to the receiving result. The above technical solution reduces the errors caused by collisions of UWB beacons during ranging by using the mechanisms of dynamic frequency modulation, random delay, random preamble and group retransmission in UWB ranging beacons, increases the number of successful ranging times at the same broadcast frequency, and greatly increases the number of access terminals while ensuring the ranging quality.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication and positioning and ranging, and in particular to a method for increasing the terminal access quantity of a beacon broadcast type UWB ranging system. Background Art

[0002] UWB (Ultra Wide Band) technology originated from the pulse communication technology that emerged in the 1960s. UWB technology uses ultra-wideband baseband pulses with extremely wide spectrum for communication, so it is also called baseband communication technology and wireless carrier communication technology. UWB technology has the characteristics of high data transmission rate, strong anti-multipath interference ability, low power consumption, low cost, strong penetration ability, low interception rate, and sharing spectrum with other existing wireless communication systems. UWB technology is widely used in wireless personal area network communications.

[0003] The UWB ranging system mainly includes a signal source and a beacon. The ranging is achieved through the interaction between the signal source and the beacon. For example, using the two-way time-of-flight method, each module will generate an independent timestamp from the beginning of its startup. The flight time of the pulse signal between the two modules can be calculated based on the timestamp information between the two modules, thereby determining the distance between the two. The system continuously implements ranging according to the set ranging frequency. According to the change in distance, it can determine whether the position of the important item installed with the beacon model has moved, and issue an alarm when movement occurs.

[0004] Chinese patent document CN109669177A discloses a "UWB ranging method and system". The actual distance between the beacon and the source is determined based on the ranging frequency, the motion data of the beacon is obtained, the updated ranging frequency is determined based on the actual distance and the motion data, and the ranging frequency is updated to the updated ranging frequency, so that the next ranging is based on the updated ranging frequency. The above technical solution has a limited number of access terminals and is difficult to meet the demand. Summary of the invention

[0005] The present invention mainly solves the technical problems that the original technical solution adopts a relatively high-frequency fixed-period broadcast, which leads to a decrease in energy efficiency in an environment where the number of terminals often changes, is not applicable to battery-type beacons, and causes system congestion. A method for improving the terminal access volume of a beacon broadcast type UWB ranging system is provided. By using dynamic frequency modulation, random delay, random preamble code and group retransmission mechanisms in UWB ranging beacons, errors caused by collisions of UWB beacons during ranging are reduced, the number of successful ranging times is increased at the same broadcast frequency, and the number of access terminals is greatly increased while ensuring the ranging quality.

[0006] The above technical problem of the present invention is mainly solved by the following technical solution: The present invention comprises the following steps:

[0007] S1 sets up the UWB ranging system;

[0008] S2 counts the current number of terminals;

[0009] S3 calculates the current broadcast cycle and performs dynamic frequency modulation; the introduction of this mechanism can not only increase the access volume of the terminal system, but also reduce power consumption, and can significantly extend the battery life of battery-powered devices.

[0010] S4 sets random delay;

[0011] S5 sets a random preamble;

[0012] S6 broadcasts with a fixed preamble;

[0013] S7 receives the signal and determines whether to resend the packet based on the reception result.

[0014] Preferably, the UWB ranging system in step S1 includes:

[0015] Indoor positioning beacons are used to periodically send broadcast signals for ranging. During the installation process, the coordinates of the beacon need to be marked on the map coordinate system according to the actual location. Indoor positioning beacons are installed on the indoor ceiling or wall. The device is battery-powered and does not require network cables or wires.

[0016] The positioning terminal is used for the location management of mobile objects. After receiving the ranging broadcast, it interacts with the beacon to measure the distance and calculate the final distance.

[0017] Communication base station, as a communication base station and used to interact with the positioning terminal for long-distance distance measurement to measure the final distance information

[0018] Server, used for wireless data transmission and recording to the cloud.

[0019] Preferably, the positioning terminal includes an MCU, a UWB ranging module and a battery, and the battery is connected to the MCU and the UWB ranging module respectively. After receiving the ranging broadcast, the UWB ranging module interacts with the beacon to measure the distance and calculates the final distance. The MCU is used to calculate the data, the battery realizes the terminal power supply, and also includes a communication module for realizing data transmission.

[0020] Preferably, the broadcast period calculation formula in step S3 is as follows:

[0021] T = 1000 / a (66> = a> = 2)

[0022] Where a represents the number of terminals in the current environment counted by the beacon. When a is 0, T is the maximum configured period. When a is 1, T is fixed at 600 ms. When a is greater than 66, T is fixed at 15 ms.

[0023] Preferably, the step S4 sets the random delay by, when the number of terminals is fixed, calculating the broadcast frequency as a fixed value, and adding a random delay based on the calculated broadcast frequency to avoid constant collisions between certain devices.

[0024] Preferably, the step S5 of setting the random preamble is that all beacons use a fixed preamble when broadcasting, add a random ranging preamble to the broadcast data packet, and when the positioning terminal receives the broadcast data packet, use the preamble carried in the broadcast packet in the subsequent ranging process. This mechanism can effectively reduce the collision between multiple beacons, thereby effectively improving the system capacity.

[0025] Preferably, the step S7 receives a signal, and if the received signal is successful, the ranging result is output. If multiple terminals collide with a beacon at the same time and an error occurs, the terminals are divided into several groups according to the last digit, and the groups are broadcast and retransmitted. This mechanism can effectively stagger multiple devices that collide with each other.

[0026] The beneficial effects of the present invention are: by using dynamic frequency modulation, random delay, random preamble and packet retransmission mechanisms in UWB ranging beacons, the errors caused by collisions in UWB beacons during ranging are reduced, the number of successful ranging times is increased at the same broadcast frequency, and the number of access terminals is greatly increased while ensuring the ranging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention.

[0028] Figure 2 It is a structural schematic diagram of a UWB ranging system of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0030] Embodiment: A method of increasing the number of terminals accessing a beacon broadcast UWB ranging system according to this embodiment, such as Figure 1 As shown, the following steps are included:

[0031] S1 sets up the UWB ranging system, which includes:

[0032] Indoor positioning beacons are used to periodically send broadcast signals for ranging. During the installation process, the coordinates of the beacon need to be marked on the map coordinate system according to the actual location. Indoor positioning beacons are installed on the indoor ceiling or wall. The device is battery-powered and does not require network cables or wires.

[0033] The positioning terminal is used for the location management of mobile objects; after receiving the ranging broadcast, it interacts with the beacon to measure the distance and calculates the final distance. The positioning terminal includes an MCU, a UWB ranging module and a battery, and the battery is connected to the MCU and the UWB ranging module respectively. After receiving the ranging broadcast, the UWB ranging module interacts with the beacon to measure the distance and calculates the final distance. The MCU is used to calculate data, the battery realizes the power supply of the terminal, and also includes a communication module for realizing data transmission.

[0034] Communication base station, as a communication base station and used to interact with the positioning terminal for long-distance distance measurement to measure the final distance information

[0035] Server, used for wireless data transmission and recording to the cloud.

[0036] S2 counts the current number of terminals.

[0037] S3 calculates the current broadcast cycle and dynamically adjusts the frequency. UWB beacons can sense the number of terminals in the current environment through ranging and dynamically adjust the broadcast frequency. The introduction of this mechanism can not only increase the access volume of the terminal system, but also reduce power consumption, which can significantly extend the battery life of battery-powered devices.

[0038] S4 sets a random delay. When the number of terminals is fixed, the broadcast frequency is calculated as a fixed value, and a small random delay is added to the calculated broadcast frequency to avoid constant collisions between certain devices.

[0039] S5 sets a random preamble. All beacons use a fixed preamble 10 when broadcasting, and add a random ranging preamble to the broadcast data packet. After receiving the broadcast packet, the terminal uses the preamble carried in the broadcast packet in the subsequent ranging process. This mechanism can effectively reduce the collision between multiple beacons, thereby effectively improving the system capacity.

[0040] S6 is broadcast with a fixed preamble.

[0041] S7 receives the signal and determines whether to resend the group according to the reception result. When multiple terminals collide with a beacon at the same time and an error occurs, the terminals are divided into 5 groups according to the last digit and the group is broadcast and resent once. This mechanism can effectively stagger multiple devices that collide with each other.

[0042] Broadcast Dynamic Frequency Modulation Example

[0043] Condition: The terminal positioning cycle is 2 seconds, and the terminal only needs to measure the distance with a single beacon once for each positioning. When the broadcast utilization rate (the number of ranging times per unit time divided by the number of broadcast times) reaches 50%, the ranging efficiency is the highest.

[0044] 1. Beacon broadcast does not use dynamic frequency modulation, assuming a fixed period of 100 milliseconds

[0045] ① When there is no terminal in the environment, the beacon will broadcast 20 times within 2 seconds, which will waste battery power.

[0046] ② When there is only one terminal in the environment, the beacon will broadcast 20 times within 2 seconds, but only once is used for normal ranging, and the broadcast utilization rate is 5%. In this case, battery power will be wasted.

[0047] ③ When there are 10 terminals in the environment, the beacon will broadcast 20 times within 2 seconds, and only 10 times are used for normal ranging. The broadcast utilization rate is 50%. In this case, the efficiency is the highest.

[0048] ④ When the number of terminals in the environment is greater than 10, the ranging delay will increase and the success rate will decrease due to the low broadcast frequency.

[0049] ㈡Beacon broadcast uses dynamic frequency modulation mechanism

[0050] ① When there is no terminal in the environment, the beacon will broadcast twice within 2 seconds so that it can respond quickly when a terminal accesses. Compared with fixed-frequency broadcasting, it can save power.

[0051] ② When there is only one terminal in the environment, the beacon will broadcast three times within 2 seconds, saving power and ensuring that the terminal positioning delay is within the required range.

[0052] ③ When there are 5 terminals in the environment, the beacon will broadcast 10 times within 2 seconds, 5 of which are used for normal ranging, and the broadcast utilization rate is 50%. In this case, the efficiency is highest and the energy efficiency is optimal.

[0053] ④ When there are 20 terminals in the environment, the beacon will broadcast 40 times within 2 seconds, 20 of which are used for normal ranging, and the broadcast utilization rate is 50%. In this case, the efficiency is highest and the energy efficiency is optimal.

[0054] Example of adding random delay to broadcast

[0055] When the number of terminals in the environment is fixed, the broadcast period of all beacons calculated by the dynamic broadcast period algorithm is also an equal fixed value. When the interval between the broadcast signals sent by two beacons is less than one broadcast packet at a certain moment, the two broadcast packets will collide in the air, and the terminal will not receive any of the two broadcasts. Because the broadcast period is equal, the next broadcast packets of the two beacons will collide again.

[0056] By adding a random delay to the broadcast cycle, the next broadcast after a collision will be staggered with a high probability, ensuring that the entire ranging system can work normally.

[0057] From the above use cases, the use of dynamic frequency modulation mechanism and the introduction of random delay on the basis of the broadcast cycle in the present invention can avoid multiple beacons from colliding with each other to the greatest extent, thereby effectively improving the stability and access volume of the system.

[0058] Packet retransmission example

[0059] When multiple terminals receive normal broadcast signals at the same time, they will reply to the beacon at the same time after 1.3 milliseconds, which will cause collision. If the group is not resent at this time, these terminals will continue to collide, and more and more terminals will join the collision, causing congestion. After adding the group retransmission, the colliding terminals can be effectively separated by the last digit of the ID for distance measurement. At this time, group broadcasting is performed according to the last digit, and only terminals with some ID last digits are selected to reply, and other terminals are discarded.

[0060] From the above use cases, it can be seen that the packet retransmission mechanism introduced in the present invention can effectively separate multiple terminals that collide with each other, thereby effectively avoiding system congestion and effectively improving system access capacity.

[0061] Effects in actual application scenarios

[0062] In the actual office personnel positioning project, 38AH disposable batteries and four beacons can provide 50 terminals with a delay of less than 500ms, a success rate of more than 90%, and no system congestion. Based on an 8-hour workday, 13 terminals measure distance once every 2 seconds, and the beacon can provide 3 years of ranging service.

[0063] Flexible adaptation and modification can be made on the following two technical points.

[0064] 1) Dynamic frequency modulation cycle mechanism

[0065] The present invention uses a period calculation formula based on each terminal measuring the distance once every 2 seconds. In actual use, the formula parameters can be adjusted according to the ranging period.

[0066] 2) Packet retransmission mechanism

[0067] When a large number of terminals are deployed and the tail numbers are evenly distributed, the group number can be changed from 5 to 10 to further prevent system congestion and improve system capacity.

Claims

1. A method for increasing the number of terminal accesses in a beacon broadcast type UWB ranging system, characterized in that: The following steps are involved: S1 sets up the UWB ranging system; S2 counts the current number of terminals; S3 calculates the current broadcast period and performs dynamic frequency adjustment, T=1000 / a, 66>=a>=2, where a represents the number of terminals in the current environment counted by the beacon. When a is 0, T is the maximum configured period; when a is 1, T is fixed at 600ms; when a is greater than 66, T is fixed at 15ms. The number of terminals in the current environment is sensed through ranging, and the broadcast frequency is dynamically adjusted; S4 sets a random delay, calculates the broadcast frequency as a fixed value, and adds a random delay based on the calculated broadcast frequency; S5 sets a random preamble; S6 broadcasts with a fixed preamble; S7 receives the signal and determines whether to resend the packet based on the reception result.

2. A method for increasing the terminal access volume of a beacon broadcast UWB ranging system according to claim 1, characterized in that: The UWB ranging system in step S1 includes: Indoor positioning beacon, used to periodically send broadcast signals for ranging; Positioning terminal, used for location management of mobile objects; Communication base station, as a communication base station and used to interact with the positioning terminal for long-distance distance measurement to measure the final distance information Server, used for wireless data transmission and recording to the cloud.

3. A method for increasing the terminal access volume of a beacon broadcast UWB ranging system according to claim 2, characterized in that: The positioning terminal comprises an MCU, a UWB ranging module and a battery, and the battery is connected to the MCU and the UWB ranging module respectively.

4. The method for increasing the terminal access volume of the beacon broadcast UWB ranging system according to claim 1, characterized in that: The step S4 of setting the random delay specifically includes, when the number of terminals is fixed, calculating the broadcast frequency as a fixed value, and adding a random delay based on the calculated broadcast frequency to avoid constant collision of certain devices.

5. A method for increasing the terminal access volume of a beacon broadcast UWB ranging system according to claim 1 or 2, characterized in that: The step S5 of setting the random preamble code specifically includes using a fixed preamble code when broadcasting all beacons, adding a random ranging preamble code to the broadcast data packet, and when the positioning terminal receives the broadcast data packet, using the preamble code carried in the broadcast packet in the subsequent ranging process.

6. The method for increasing the terminal access volume of the beacon broadcast UWB ranging system according to claim 1, characterized in that: The step S7 receives the signal, and if the signal is received successfully, the ranging result is output. If multiple terminals collide with a beacon at the same time and an error occurs, the terminals are divided into several groups according to the tail numbers, and the groups are broadcast and retransmitted.

7. A method for increasing the number of terminal accesses in a beacon broadcast UWB ranging system according to claim 6, characterized in that: Broadcast is performed in groups according to the last digit of the ID, and only terminals with some of the last digits of the ID are selected to reply, while other terminals are discarded.

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