The concept of Internet of things is discussed. The key problem of the Internet of things is how to solve the problem of low-cost, low-power, flexible and reliable wireless transmission of all kinds of information below the public network and within the distance of a few meters to thousands of meters. At the same time, it is considered that the active electronic tag is the hope to solve this problem. Various active electronic tags used at home and abroad are compared and analyzed; This paper points out the problems existing in the existing active electronic tags, and introduces a simple and feasible new solution with completely independent intellectual property rights, interactive intelligent electronic tag technology.
Basic technical requirements of Internet of things
Table of Contents
- Basic technical requirements of Internet of things
- Active electronic tag
- Expectations of IOT for active electronic tags
- Current status of active electronic tags
- Comparison of basic physical properties
- Comparison of working methods
- Functions of existing active electronic tags
- Interactive intelligent electronic tag communication technology with independent intellectual property rights in China
We can understand the Internet of things as the extension of the Internet to all details of the world. If the important feature of the Internet is the network connection between computers, the important feature of the Internet of things is the wireless connection between low-cost and low-power MCU and computers.
The Internet of things should at least solve the following problems:
- Identification and authentication;
- Sensor data acquisition;
- Give orders.
The means used to solve these problems must also meet the following basic requirements:
With the requirement of low cost, the cost of identification and information collection for hundreds of millions of people and things everywhere must be low.
According to the requirements of wireless transmission and on-demand work, thousands of things, things and people, people and people should be connected together. Obviously, wireless connection must be the main way. In order to avoid the electromagnetic pollution of the environment, it is necessary to control the time and space occupied by a large number of wireless signals, and only allow them to transmit signals in the limited space and time they need to work. With the requirement of high integration, the equipment undertaking information transmission must also be very small.
The wireless device used must be ultra-low power consumption.
It must be capable of two-way communication, that is, both data acquisition and signal control.
It shall also have the ability of long-distance communication (often more than kilometers), such as street lamp control, etc.
Obviously, the Internet of things cannot be just a single network, but should be the integration of various information transmission and collection means. It is a “ubiquitous network” including bar codes, various sensors, active electronic tags, computers, mobile phones, various communication public networks, etc. However, when we comb the whole information connection and transmission process of the Internet of things from top to bottom, it is not difficult to find that various public communication networks required for long-distance information transmission have been established and are very mature. At most, they are only improved and upgraded. At the lowest level directly related to people or things, short-range identification technologies such as bar code tags and passive electronic tags, as well as various common sensor technologies (temperature, humidity, pressure, etc.) for collecting object status information are also relatively mature. The key to the problem is how to transmit the information about objects and people collected by sensors, bar code tags and passive electronic tags to the public network tens of meters or even one kilometer away on the premise of meeting the above basic requirements.
Active electronic tag
Because the active electronic tag itself is a simple structure of single chip microcomputer and wireless micro power transceiver, and has the characteristics of small volume, low cost, low power consumption and long-distance transmission, it has naturally become the hope for people to solve the problem of information transmission below the public network in the Internet of things. In the business case report submitted by the IEEE International standard setting group for active electronic tags, we can clearly see people’s expectations:
Scope of recommended standards
It can support effective communication between reader and tag, support connection with sensor, and has low working duty cycle and low transmission power; RF working parameters can be set flexibly; It supports one-way and two-way communication, point-to-point and point-to-multipoint communication, communication between tags, multi-level relay of data, processing massive tags, and data read-write authentication; It supports precise positioning, has high working reliability, and uses the frequency band commonly used in the world; It can coexist with other existing working systems in the frequency band without mutual interference.
Purpose of recommended standards
It provides a low-cost, low-power, flexible and reliable communication method to support identity recognition and sensor information transmission. Air interface can support various requirements of electronic tag factory wide applications, and has improvement space and flexibility for large-scale and wide use all over the world.
Necessity of the project
For a widely needed international standard, it should at least include the following requirements:
- Ultra low power consumption (low duty cycle);
- Low transmission power;
- One way and two-way communication;
- It can handle massive tags;
- The reader and writer can not only broadcast tags on demand, but also communicate with each other through mesh network;
- Reader / writer broadcast communication;
- Authorized certification;
- Integrated sensor to transmit sensor information;
- Accurate positioning capability;
- 100m communication distance;
- International general channel;
- The channel bandwidth shall be less than 3MHz;
- It can coexist with other systems working in the channel without interference.
From the business case report submitted by the IEEE active electronic tag international standard development group, We can also learn about the current situation of active electronic tags: “In order to reduce energy consumption, most active tags today use one-way ID transmission, whose only purpose is to identify and locate another u without considering congestion and signal collision. Active electronic tags need to have the ability of two-way communication and long-distance communication, and the ability to handle a large number of tags, but the power consumption is very low at the same time”, “At present, there is no international standard proposal to meet this need”.
In order to make a clearer statement of the current situation of active electronic tags, we might as well make a simple comparison of various active electronic tags, including basic physical properties, working mode and functions, and briefly comment on some of the main problems.
Comparison of basic physical properties
(1) Communication frequency
- 400MHz, 800MHz and 900MHz UHF systems have narrow bandwidth, many users, crowded frequency bands and large interference;
- 433MHz: car radio, amateur radio, interphone and various digital radio stations;
- 800 ~ 900MHz: mutual interference with mobile communication;
- 5. 8GHz has high technical requirements, the technology is not very mature, the existing chip has short communication distance, high power consumption and high cost;
- 2.4GHz is quite mature and the cost is low. As an electronic tag, the communication rate is sufficient, and there are many corresponding products. Although there are many users in this frequency band, due to the good planning and management of this frequency band, it is generally a new product and adopts new technologies (frequency hopping or spread spectrum technology) with good compatibility and coexistence.
(2) Communication mode
The existing general tags, including most 40omhz, 8oomhz, 90omhz and general 2.4GHz active electronic tags, basically adopt the relatively backward point frequency narrowband communication mode due to the consideration of technical difficulty and cost. The direct problems caused by this communication mode are:
Poor system stability. Because the working frequency point of the system is very narrow, the crystal oscillator that determines the working frequency of the system will change its natural frequency due to temperature change (temperature drift) and its own aging, resulting in the change of the working frequency point of the system, which will deviate from the limited working range, so that the system can not work normally. There are many such examples.
Tag movement speed is limited. When the electronic tag moves rapidly, due to the influence of multipath effect and Doppler effect, the signal frequency may shift out of the originally narrow system working range, which also makes the system unable to work normally.
Poor coexistence with other wireless systems. The point frequency narrowband communication mode is easy to be disturbed by environmental noise, and it is also easy to interfere with other communication systems, especially in some particularly crowded frequency bands such as 400MHz, 800MHz and 900MHz. With direct sequence spread spectrum communication, even if the system is interfered at one or several points, the system can repair the interfered part through the correlation between communication chips, so the system communication is not easy to be affected. Because the spread spectrum system works in a wide frequency band, the transmission energy at each working frequency point is very small, so it is difficult to interfere with other communication systems.
Comparison of communication distance: under the same transmission power and modulation mode, the system using DSSS communication mode has a longer communication distance due to the spread spectrum gain.
(3) Communication rate
The communication rate of high frequency system is higher than that of low frequency system.
Direct sequence spread spectrum can increase the confidentiality of air communication by using PN code. In addition, because the communication rate of high-frequency system is higher than that of low-frequency system, it provides more data space for software encryption.
(5) Large volume D
Due to the length of the wave in the high frequency system, the size of the tag can be made very small.
(6) Diffraction, reflection, drilling seam, transmission capacity
The diffraction ability of low-frequency system is better than that of high-frequency system, and the transmission ability of high-frequency system through small gaps is better than that of low-frequency signal. High frequency signals are more transmitted around obstacles through the reflected signals on the building surface. A large number of application practices show that by making rational use of the propagation characteristics of high-frequency signals, 2.4GHz DSSS active electronic tags can well meet the needs of various short-range communications.
Comparison of working methods
- (1) The method of periodically transmitting its own ID number. This is the working mode commonly used at present: when the electronic tag works in this working mode, its transmission power, transmission time interval and transmission channel are fixed. This working mode is also the basic working mode of positioning tag in the ISO international standard of real time positioning system (RTLS).
- (2) Low frequency wake-up and high frequency operation are adopted. In order to reduce the power consumption of the electronic tag, a passive low-frequency detection system is installed in the electronic tag. The system uses the strong low-frequency wake-up signal transmitted by the low-frequency exciter antenna to make the low-frequency detector in the electronic tag generate a signal to turn on the high-frequency communication system, so that the electronic tag will enter a certain working state, and then enter the sleep to be activated state after the work is completed. Because the low-frequency detection system in the tag is passive, the power transmitted by the activation antenna of this low-frequency system must be very large, and the range in which it can activate the tag is also very limited. Therefore, the flexibility of the system is greatly limited.
- (3) Two sets of communication systems are adopted: UWB plus 2.4GHz, UWB plus 125kHz low frequency, and 2.4GHz plus 125kHz low frequency (refer to the relevant documents provided by IEEE active electronic tag international standard working group at its meetings from March 2009 to January 2010). In addition, this practice can also be clearly seen in the two-way communication system defined in RTLS international standards (ISO / IEC 24730-2 and ISO / IEC / JTCI / SC31 / WG3 / SG1). In addition to the 2.4G communication system, a set of active low-frequency receiver is also installed in the electronic tag of the system to monitor and receive signals from programmer and excjter periodically (200ms). This working mode is only used to realize two-way communication. The problem with this working mode is that the tag itself becomes very complex, the tag consumes a lot of power, the battery life is short, and the communication distance between the tag and pr0grammer and exciter is also very close. Therefore, this two-way communication opportunity can be used, To increase the flexibility and adaptability of the system is very limited. The super long response time is also a problem of the system.
Because the tags with two working modes (2) and (3) not only have complex structure, high cost and large volume, but also because the low-frequency communication distance is very short, the working flexibility of the tag is greatly reduced, and its application range is greatly limited.
This paper mainly discusses the problems existing in the first tag working mode commonly used at present. First, in terms of time and space, they can’t work on demand (that is, they work when they need to work and where they need to work);
Secondly, they can not adjust the working parameters and methods of the tag according to the actual needs. Thus:
- (1) They will inevitably cause electromagnetic pollution of the environment. Just imagine, with the more and more extensive application of electronic tags, especially the development of Internet of things applications, if a large number of electronic tags always transmit all kinds of RF signals, we will be forced to live in an environment full of a large number of electromagnetic signals, which is obviously a living space that everyone of us can’t stand.
- (2) In general, at one time, we are often only interested in the recognition of a specific target image, so we only need to receive the signal of the target electronic tag, and the signal transmitted by other tags is the interference signal. Moreover, the signals transmitted by a large number of tags will also interfere with other wireless systems working on this public channel.
- (3) The electronic tag constantly sends out signals, which will also increase the consumption of the battery and reduce the service life of the battery.
- (4) The energy consumed when the electronic tag continuously transmits signals is directly proportional to the transmission power. For long-distance identification, such as ships, the electronic tag must use large transmission power to transmit signals, which will greatly reduce the service life of the electronic tag battery.
- (5) The shorter the signal interval of the electronic tag, the faster the battery consumption. Many practical applications require the rapid reading of the electronic tag, for example, the identification of fast passing vehicles. This is in contradiction with the need to increase the time interval of transmitting signals for the purpose of saving power.
- (6) If we need the electronic tag to transmit more relevant information in addition to its own ID, the time required for each launch of the electronic tag will be longer, which needs to occupy more air time and consume more battery energy. This not only increases the probability of signal collision, but also reduces the service life of the battery.
- (7) Because the tag can not adjust its transmission power according to needs, when it is used for positioning, it can not well adapt to the working environment of different space sizes.
- (8) Poor confidentiality: when used for military purposes, because the electronic tag always sends signals outward, the signal exposure time is long and the exposed space range is large, so it is easy for the enemy to intercept and analyze the exposed signals.
- (9) Poor adaptability: because the electronic tag can not adjust its own working parameters and working mode according to the actual application needs at any time, its working adaptability is poor.
The existing active electronic tags can only undertake the functions of identification and simple positioning. Many functions involving two-way communication can be completed: such as authorization and authentication, data reading and writing records, work instruction transmission, etc. can not be realized at all, let alone meet the various needs of today’s Internet of things information transmission on the premise of low cost and low power consumption.
Interactive intelligent electronic tag communication technology with independent intellectual property rights in China
If the information recently provided by the IEEE International active electronic tag standard setting group reflects the latest level of active electronic tag technology in the west, it should be said that we are currently in a leading position in the research of the key short-range information transmission technology of the Internet of things. In nearly six years, a new interactive intelligent electronic tag communication technology by using the latest short-range wireless micro power communication technology achievements in the world, including RFID and ZigBee, to solve various problems in domestic production practice. This is a multifunctional active electronic tag technology with completely independent intellectual property rights, simple structure, small volume, low cost, low power consumption, reliable operation, and ultra long-distance communication capability. It not only meets all the requirements of the IEEE active electronic tag international standard formulation group for the ideal standard proposal, but also higher than the requirements of the standard. For example, under the condition of ensuring ultra-low power consumption, it can not only bear the identification of different distances (a few meters to 2 kilometers), but also flexibly meet the needs of various wireless information transmission of the Internet of things. More importantly, this new technology is a technology verified by many practical applications.
Interactive intelligent electronic tag communication technology solves the problem of tag two-way communication at low cost by automatically jumping to the working channel; The problem of tag power consumption is solved by fast filtering technology of invalid signal; By using the combination of ultra-low power standby mode and fixed action, the problems of on-demand and flexible operation of tags are solved; Through automatic time division, frequency division and code division, the processing problem of massive electronic tag information is solved; By using the method of automatically changing the transmission power, the problem of accurate positioning in different application environments is simply and effectively solved.
Main working parameters of interactive active electronic tag
The interactive active electronic tag works in the international 2.4G ISM frequency band; The direct sequence spread spectrum (DSSS) working mode with 1MHz bandwidth is adopted, which not only improves the anti-interference ability and working stability of the system, but also better realizes the coexistence with other wireless communication systems in the ISM common frequency band.
Basic working mode
- (1) Work on demand in time and space. The interactive smart electronic tag usually does not transmit any RF signal to the outside, and is in a low-power standby state (the average power consumption is < 20ua, the average wake-up speed is 0.5s and can be adjusted arbitrarily). When it needs to work, it can pass a 1-10 MW coordinator wakes it up on the wake-up channel at a distance of 0 ~ 2000m (the wake-up distance is adjustable) and gives the required work instructions; The electronic tag works according to the work order, and immediately enters the low-power standby state on the wake-up channel after completing the required work, waiting for the next wake-up and new work order.
- (2) Work on demand in working mode. According to the needs of different applications, the electronic tag can write the working mode package required by the application: for example, transmitting ID mode, transmitting positioning signal package mode, reading and writing data mode, sensor information acquisition and transmission mode, entering the working mode of dialogue with the reader, simply processing the received data, etc. The system can transmit the instructions and relevant parameters of the required working mode through the coordinator or reader at any time according to different needs.
- (3) Select the optimal working parameters and working channels as needed. The interactive electronic tag can select different RF working parameters, scan and find clean working channels according to needs, and can also change the working parameters through the coordinator or reader at any time during the working process; By scanning and looking for clean working channels, interference from other working systems can be avoided. Even if there is a broadband system like WiFi in the workplace, we can select the required 1m bandwidth working channel within the 5m bandwidth range between the two WiFi channels.
- (4) Using the uniqueness of each tag ID number, the electronic tag can automatically divide time, frequency and code according to the work order to solve the problem of processing a large number of tags.
Without using two sets of communication systems (without adding any hardware), in a way of low cost, low power consumption and high reliability (average power consumption < 20ua), it ensures that a two-way communication connection can be quickly established between the electronic tag and the reader at any time at a distance of several centimeters to 2000 meters, so as to realize the electronic tag in time and space It is an efficient working mode that can work according to actual needs in terms of working parameter selection and working mode. The benefits are obvious:
- (1) The electromagnetic pollution to the environment is greatly reduced. It improves the signal receiving efficiency and provides a strong guarantee for the requirement of coexistence with other existing communication systems without mutual interference.
- (2) The problem of battery life of active electronic tag is well solved. Because the electronic tag is usually in a low-power standby state, it consumes limited electric energy only in a very short time when it needs to work. Therefore, the battery life can be very long. Especially for long-distance targets, such as ship identification and positioning, land and Shanghai search and rescue, because the power consumption of long-distance electronic tags is no different from that of short-range electronic tags, and the working time of high-power transmission signals is very short, so the overall battery consumption is still very small. This is what other electronic tags can’t do.
- (3) High flexibility. Because the interactive electronic tag can adjust its working parameters and write and call different working programs according to the needs of practical applications anytime and anywhere. Therefore, it can fully meet the needs of various Internet of things information transmission, including long-range and short-range target recognition and positioning.
- (4) All in one card function. The smart electronic tag does not need to be reset to meet the needs of remote reading and writing recognition and ultra close reading and writing authentication within a few centimeters.
- (5) High confidentiality. In addition to using general software encryption, interactive electronic tags usually do not transmit any signal. They only transmit signals within the limited time required to work and within the limited space range required to work (controlling the signal coverage by adjusting the transmission power). Therefore, the probability of signal exposure is small and it is difficult to be found, stolen, analyzed and cracked; In addition, when the wake-up signal transmitted to the electronic tag through the coordinator, a special PN code and wake-up password can also be used to increase the confidentiality of system communication. Therefore, the interactive intelligent electronic tag system has very high communication security characteristics.
- (6) By means of automatic time division, frequency division and code division, the problem of processing massive tag information in a short time is solved.
- (7) By organically combining regional positioning (Cell- ID) and precise positioning, interactive intelligent electronic tags successfully integrate two different functions of radio frequency identification and precise positioning (RTLS).
- (8) Simple structure, low cost and small volume. There is no difference with the simplest active electronic tag in hardware, but a completely different control method is adopted in software.
- (9) It has passed the test of application practice for more than five years, from the strict laboratory of vehicle path identification of Henan Expressway and many on-site actual tests to the implementation of the intelligent vehicle management project of Asia’s largest bus parking lot in Pudong, Shanghai; From the official launch of the personnel automatic management system project of the bank treasury, to the full deployment of the automatic temperature acquisition system of the urban heating system in Beijing, to the order requirements of a large number of urban single lamp automatic control systems, many production application practices and strict tests by authoritative institutions have all proved the practicality of this interactive intelligent tag technology Advanced nature and huge market application prospect.
In order to reduce energy consumption, most active electronic tags today use one-way ID transmission, whose only purpose is to identify and locate, without considering signal congestion and collision, as well as a series of other problems arising therefrom; At the same time, they can not meet the rapidly growing needs of various application fields, especially the urgent needs of information transmission of the Internet of things. In fact, the existing active RFID technology and the problems existing in the end information acquisition and control of the Internet of things can be simply attributed to how to solve the problems of ultra-low cost, ultra-low power consumption, flexible and reliable wireless transmission of all kinds of information below the public network and within a distance of a few meters to thousands of kilometers. The interactive intelligent electronic tag technology is a simple and practical solution verified by practice.
Source: China Electronic Tags Manufacturer – Actility Technologies Company Limited (www.tractility.com)
Actility provides powerful security solutions for retail store management to prevent asset and property losses, improve transaction security, and provide intelligent analysis. We produce AM/EM/RFID systems, EAS tags, EAS soft tags, EAS safer, lanyards, detachers and all kinds EAS accessories products. Infrared people counter and camera people counter is available.
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