An article to help you understand UWB

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An article to help you understand UWB [Copy link]

UWB technology has been in the spotlight because of its application in Apple mobile phones, and like the recent lithography machines, it has received the curious eyes of the public. In fact, UWB is not a new technology. Its application in the military industry dates back to the last century, when the United States and the Soviet Union were still in the Cold War and China was still in the process of reform and opening up. It has also been used in the industrial field for nearly 20 years, and various technology service providers have fought for several rounds in the market. However, the news of its application in the commercial field, which was only released last year, finally brought UWB to the forefront (which is a cause for celebration).

This article will introduce UWB technology in all aspects, so that everyone can have a deeper understanding of UWB.

What is UWB?
UWB stands for Ultra Wide-Band, a new type of wireless communication technology. It does not use a sinusoidal carrier, but uses nanosecond non-sinusoidal narrow pulses to transmit data. Therefore, it occupies a large spectrum range. Although wireless communication is used, its data transmission rate can reach hundreds of megabits per second.
UWB technology uses ultra-wide baseband pulses with extremely wide spectrum for communication, so it is also called baseband communication technology and wireless carrier communication technology. It is mainly used in military radar, positioning and low interception rate/low detection rate communication systems.

Development History of UWB
UWB technology was born in the 1960s, and its application has been limited to military, radar positioning and ranging. It was not until February 2002 that UWB was approved by the FCC for civil and commercial communications. Soon after, Japan opened the ultra-wideband frequency band in August 2006. In March 2007, ISO officially approved the MB-OFDM standard submitted by the WiMedia Alliance, which officially became the first international standard for UWB technology.
Currently, more than 20 manufacturers have developed and launched UWB technology chips, application development platforms and related equipment. Among them, the leading manufacturers are mainly American manufacturers, and also include some companies in Israel, Japan, the United Kingdom, Europe and Taiwan.

Compared with advanced foreign countries, my country's UWB research and development started relatively late. Since 1999, Chinese researchers have begun to pay attention to the development of UWB technology. In 2001, the national "863" plan launched a high-speed UWB experimental demonstration system research and development project. After selection, Southeast University, Tsinghua University, and the University of Science and Technology of China conducted research and development respectively, and each proposed a plan, which was completed and passed the acceptance in December 2005 and April 2006 respectively. At the 2011 China International Information and Communication Exhibition, Shenzhen Guoren Communication Co., Ltd. launched the Ultra-Wideband Digital Fiber Distribution System (UW-DDS), which is the latest solution that can realize multi-standard and multi-service common access, coordinated development, and co-construction and sharing. It has been applied in the National Grand Theater and other places and has achieved great success.

With the initial emergence of indoor positioning business models and the strong promotion of mainstream chip manufacturers, location service providers, integrators, etc. in various links of the industrial chain, UWB technology currently has a large number of industry application cases in the domestic and even global markets.

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Technical features
UWB has two main applications: ranging and positioning. The factors supporting these two functions are the following technical features:
1. High precision
It has centimeter-level high-precision positioning capability. The time domain width of UWB signals is extremely narrow. When measuring, the receiving end can obtain extremely high time resolution. In simple terms, the time measurement is accurate, which is the basis for achieving high-precision positioning.
At the same time, it also has a strong anti-multipath capability. It is difficult for signals arriving from different directions to overlap and interfere, which is also very beneficial for high-precision positioning.
2. Low power consumption
The UWB system uses periodic pulses to send data. The pulse duration is very short, generally between 0.20ns and 1.5ns, and the duty cycle is very low, which saves a lot of power consumption for sending continuous carriers, so the power consumption can be very low.
3. High security
The physical layer technology of the UWB communication system has natural security performance. Its bandwidth is large, and the transmission power spectrum density is lower than the noise. The information it carries is submerged in the noise, and the probability of being intercepted and interfered is very low. On the contrary, the probability of affecting other wireless communications (such as WIFI) is also very low. In summary, it means that you do not interfere with others, and it is difficult for others to interfere with you.
4. Low cost
Deploying a UWB positioning system requires certain hardware procurement costs, but the UWB base* has a large coverage range, with a typical radius of 50-150 meters. In the same area, fewer devices need to be deployed. At the same time, once the UWB system is deployed and debugged, it almost does not need to be modified. It can be used for 10 years with a one-time investment, and the operating cost is extremely low.

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Distance measurement and positioning principle
The distance measurement principle of UWB
TOF
(Time of flight, TOF) is a two-way distance measurement technology, which calculates the distance by measuring the round-trip flight time of the UWB signal between the base and the tag. According to the mathematical relationship, if the distance from a point to a known point is a constant, then this point must be on a circle with the known point as the center and the constant as the radius. If there are two known points, there are two intersection points. Three circles are made with three known points and distances, and they intersect at the same point, which is the location of the tag.

The distance measurement based on the TOF positioning method does not rely on the time synchronization between the base station and the tag, so there is no error caused by clock synchronization deviation, but the time of the TOF ranging method depends on the clock accuracy, and the clock offset will cause errors. In order to reduce the ranging error caused by the clock offset, the measurement method in both positive and negative directions is usually adopted, that is, the remote base station sends the ranging information, the tag receives the ranging information and replies, and then the tag initiates the ranging information, and the remote base station replies. By calculating the average flight time, the time offset between the two is reduced, thereby improving the ranging accuracy.

TDOA
(Time Difference of Arrival, TDOA) is a positioning method that uses the time difference of arrival, also known as hyperbolic positioning. The tag card sends a UWB signal to the outside, and all base stations within the tag positioning distance will receive the wireless signal. If there are two base stations with known coordinates that receive the signal, the distance interval between the tag and the base station is different, so the time nodes of the two receiving the signal are different. According to the mathematical relationship, the point with a constant distance to the two known points must be on the hyperbola with these two points as the focus. Then there will be four hyperbolas if there are four known points (four positioning base stations), and the intersection of the four hyperbolas at one point is the location of the tag.
The TDOA algorithm does not directly use the signal arrival time, but uses the time difference of multiple base stations receiving the signal to determine the location of the mobile target. Therefore, compared with TOA, it does not need to add a special timestamp for clock synchronization, and the positioning accuracy is relatively improved.

UWB positioning principle
After knowing the distance measurement principle of UWB, it is easy to understand the indoor positioning principle of UWB. The indoor positioning function of UWB is very similar to the satellite principle, that is, by arranging 4 positioning bases with known coordinates indoors, the equipment of the person to be positioned carries a positioning tag, the tag sends pulses at a certain frequency, and continuously measures the distance with the 4 bases with known positions, and determines the position of the tag through a certain precise algorithm.

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Application Scenarios
UWB applications are mainly suitable for three scenarios: access management, location services and communication between devices.

The three major application scenarios are mainly aimed at smart home and smart office, smart city, smart transportation, consumer electronics, new retail, consumption and medical fields.

Hands-Free Access Control uses UWB technology to achieve access control. When a person approaches the door, it is automatically sensed and recognized to unlock the door, replacing the traditional fingerprint and password application scenarios that require interactive contact.

Location-Based Services (LBS) are based on UWB's high-penetration and stable transmission performance under multiple paths, enabling precise indoor positioning and big data analysis.

Device interconnection (P2P Applications) is mainly used for data interconnection between devices, such as video teleconferencing, autonomous driving V2X, AR/VR games, remote payments, etc.

Positioning solution
At present, in the UWB positioning service market, various service providers have sprung up like mushrooms after rain, rushing into the market, wanting to share a cup of the fresh soup of the positioning market. By comparing the positioning solutions of various companies, the author summarizes the more common parts of each positioning solution. Other specific technical services for specific scenarios are not discussed. The main functions are as follows:
1. Real-time positioning and personnel distribution
Unique tags bind personnel information, real-time location tracking, statistics of personnel location and distribution heat map, grasp personnel dynamics anytime and anywhere, and facilitate personnel management.
2. Personnel tracking and behavior monitoring
It can monitor various behaviors in the area: regional timeout, regional gathering, long-term immobility, etc., to meet safety management requirements at any time and ensure personal safety. And it can mark key personnel for behavior analysis and monitoring.
3. Electronic fences and high-risk areas
The system can set up electronic fences at any time to control personnel authority to ensure that only authorized personnel can enter high-risk areas. Fence management implements entry and exit restrictions to ensure production safety.
4. Historical trajectory storage and query
The system can store personnel historical trajectories for unlimited time, which is used to query and analyze personnel behavior, provide a basis for event analysis, and analyze personnel behavior and monitor key personnel.
5. Access control and video linkage
The system performs access control linkage, compares and confirms that the person card is consistent; and performs video tracking in the area, which can observe the on-site situation in the area at any time, facilitate real-time management, and effectively ensure the safety of personnel and assets.
6.
On-the-job monitoring It can meet the security business, and the safety inspectors can be on-the-job monitoring to ensure safe production. It can also provide convenient monitoring routes for safety inspectors in combination with personnel density and high-risk reminders, and improve the efficiency of safety monitoring management.

Summary
If you want to use UWB, you must have a fundamental understanding of it. UWB has a very broad application space. Healthy market competition and in-depth technical research can stimulate the unlimited potential of technology. In the foreseeable future, UWB technology will surely have more and wider applications. Let's wait and see.

熹妃飞

The knowledge of the masters is so amazing. I have learned a lot here.

空宁幽远

ohahaha Published on 2020-12-8 20:46 Application Scenarios UWB applications are mainly suitable for three scenarios: access management, location services, and communication between devices. The three application scenarios are mainly for smart...

Nice summary, clear and concise.