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2.1 RFID
The RFID air interface communication protocol specification basically determines the working type of RFID and the communication rules between the RFID reader and the corresponding type of RFID tag, including: frequency, modulation, bit encoding and command set. ISO/IEC has formulated air interface protocols for five frequency bands.
(1) ISO/IEC 18000-1 "Information technology - Radio frequency identification based on single item management - Part 1: Reference architecture and standardized parameter definitions". It specifies the communication parameter table between readers and tags and basic intellectual property rules that are commonly followed in the air interface communication protocol. In this way, the standards corresponding to each frequency band do not need to repeat the same content.
(2) ISO/IEC 18000-2 "Information technology - Radio frequency identification based on single item management - Part 2: Parameters for air interface communications below 135 kHz". It specifies the physical interface for communication between tags and readers. The readers should have the ability to communicate with Type A (FDX) and Type B (HDX) tags; it specifies protocols and instructions, as well as anti-collision methods for multi-tag communication.
(3) ISO/IEC 18000-3 "Information technology - Radio frequency identification based on single item management - Part 3: Parameters Air interface communications at 13.56MHz". It specifies the physical interface, protocol and commands between the reader and the tag, as well as the anti-collision method. The anti-collision protocol can be divided into two modes, and mode 1 is divided into a basic type and two extended protocols (slotless non-terminated multi-responder protocol and slot-terminated adaptive polling multi-responder reading protocol). Mode 2 uses the time-frequency multiplexing FTDMA protocol with a total of 8 channels, which is suitable for situations with a large number of tags.
(4) ISO/IEC 18000-4 "Information technology - Radio frequency identification based on single item management - Part 4: Parameters for 2.45 GHz air interface communications". It specifies the physical interface, protocol and commands between the reader and the tag, as well as the anti-collision method. The standard includes two modes. Mode 1 is a passive tag working mode in which the reader speaks first; Mode 2 is an active tag working mode in which the tag speaks first.
(5) ISO/IEC 18000-6 "Information technology - Radio frequency identification based on single item management - Part 6: 860 MHz - 960 MHz air interface communication parameters". It specifies the physical interface, protocol and command between the reader and the tag, as well as the anti-collision method. It includes the interface protocols of three passive tags, Type A, Type B and Type C, with a maximum communication distance of 10m. Type C was drafted by EPCglobal and approved in July 2006. It has greatly improved the recognition speed, reading and writing speed, data capacity, anti-collision, information security, frequency band adaptability, and anti-interference. The V4.0 draft was submitted in 2006. It expands the characteristics of electronic tags with auxiliary power supply and sensors, including tag data storage methods and interactive commands. Active tags with batteries can provide a wider range of reading capabilities and stronger communication reliability, but they are larger in size and more expensive.
(6) ISO/IEC 18000-7 "Information technology - Radio frequency identification based on single item management - Part 7: 433 MHz active air interface communication parameters". It specifies the physical interface, protocol and commands between the reader and the tag, as well as the anti-collision method. Active tags have a large reading range and are suitable for tracking large fixed assets. They are active electronic tags.
In addition, there are 3 commonly used RFID protocols:
(1) ISO/IEC 14443 “Identification cards – Contactless integrated circuit cards – Proximity cards”
The international standard ISO 14443 defines two signal interfaces: Type A and Type B. ISO 14443A and B are incompatible with each other.
1. ISO 14443 Type A
ISO 14443 Type A
(Also known as ISO 14443A) is generally used for access control cards, bus cards and small-value stored-value consumption cards, and has a high market share.
Example:
1 ) MIFARE ULtralight (MFO ICU1X): commonly known as U10 in China. This chip has no encryption function, only system encryption, memory is 64 bytes, typical application: Guangzhou-Shenzhen high-speed train tickets. (Also: MIFARE ULtralight C, also called U20, this chip can be encrypted, memory is 192 bytes). The internal code bits of these two chips are the same, but the internal code data is different. (Domestic compatible chips include FM11RF005 memory 64 bytes, BL75R12 memory 64 bytes, etc.)
2 ) MIFARE Std 1k (MF1 IC S50): It is commonly called MF1 S50 in China. It is mainly used in one-card systems. The memory is 1KB, with 16 sectors, each sector has 4 blocks, and each block has 16 bytes. The initial password is 12 Fs. (Domestic compatible chips include FM11R08, ISSI4439, TKS50, BL75R06, etc.)
3 ) MIFARE Std 4k (MF1 IC S70): It is commonly called MF1 S70 in China. It is mainly used in one-card applications. The memory is 4KB, with a total of 40 sectors. The first 32 sectors are the same as S50, each sector has 4 blocks, and the last 8 sectors are 16 blocks, each block is 16 bytes. The initial password is 12 Fs. (Compatible domestic chips include ISSI4469, FM11RF32 and Huada's S70).
4 ) Mifare DESFire 4k (MF3 IC D41/D40): commonly known as MF3 in China. Typical application: Nanjing Metro.
5 ) SHC1102: Produced by Shanghai Huahong. Typical application: Shanghai ICP card.
2. ISO 14443 Type B
ISO14443B is more suitable for CPU cards due to its higher encryption coefficient. It is generally used for ID cards, passports, UnionPay cards, etc. The current second-generation electronic ID card standard is the ISO 14443 Type B protocol.
Example:
1 ) SR176: Produced by STMicroelectronics (ST), Switzerland.
2 ) SRIX4K: produced by STMicroelectronics (ST), Switzerland.
3 ) THR1064: Produced by Beijing Tongfang. Typical application: Olympic tickets.
4 ) AT88RF020: Produced by Atmel (ATMIL) of the United States. Typical application: Guangzhou subway card.
5 ) Second-generation resident ID cards: produced by Shanghai Huahong, Beijing Tongfang THR9904, Tianjin Datang and Beijing Huada.
(2) ISO/IEC 15693 “Identification cards – Contactless integrated circuit cards – Proximity cards”
The reading and writing distance of ISO 14443A/B is usually within 10cm, and it is widely used. However, the reading and writing distance of ISO 15693 can reach 1m, and it is more flexible in application and compatible with ISO 18000-3 (many of my country's national standards are compatible with most of ISO 18000).
Example:
1 ) ICODE SLI (SL2ICS20): It is commonly called ICODE 2 in China (memory is 1Kbit), and this model is commonly used. It is compatible with BL75R05 and FM1302N in China. (In addition: ICODE SLI-S memory is 2048bit, ICODE SLI-L memory is 512bit, these two chips are not commonly used in China.)
2 ) Tag-it HF-1 Plus: commonly known as Tl2048 in China, produced by Texas Instruments (TI for short) of the United States.
3 ) EM4135: Produced by EM in Switzerland.
4 ) BL75R04: produced by Shanghai Belling and FM1302T (produced by Fudan University), compatible with TI's Tag-it HF-1 Plus.
(3) ISO 18092 “Interfaces and protocols for short-range wireless communication and information exchange between information technology systems”
The NFC protocol specifies some specifications for short-range wireless communication technology. NFC belongs to the category of RFID, but it is somewhat different from RFID, so this article will explain NFC in a separate section.
2.2 NFC
2.2.1 NFC Overview
NFC is the abbreviation of Near Field Communication, which is a short-range high-frequency wireless communication technology that allows contactless point-to-point data transmission (within 10 cm) between electronic devices to exchange data.
NFC provides a simple, touch-based solution that allows consumers to exchange information, access content and services simply and intuitively. This technology evolved from contactless radio frequency identification (RFID) and is backward compatible with RFID. It was first promoted by Philips, Nokia and Sony and is mainly used in handheld devices such as mobile phones. Due to the inherent security of near-field communication, NFC technology is considered to have great application prospects in areas such as mobile payments. NFC integrates contactless card readers, contactless cards and peer-to-peer functions into a single chip, creating countless new opportunities for consumers' lifestyles.
This is an open interface platform that can quickly and actively set up wireless networks. It is also a virtual connector that serves existing cellular networks, Bluetooth and wireless 802.11 devices. Unlike RFID, NFC uses two-way identification and connection. It works in the 13.56MHz frequency range within a distance of 20cm. It can quickly and automatically establish a wireless network, providing a "virtual connection" for cellular devices, Bluetooth devices, and Wi-Fi devices, allowing electronic devices to communicate over short distances.
2.2.2 NFC Technology Principle
NFC devices can exchange data in active or passive mode.
In passive mode, the device that initiates NFC communication, also known as the NFC initiator (master), provides the RF field during the entire communication process. It can select one of the transmission speeds of 106kbps, 212kbps or 424kbps to send data to the other device. The other device, called the NFC target device (slave device), does not have to generate an RF field, but uses load modulation technology to transmit data back to the initiator at the same speed. Mobile devices mainly operate in passive mode, which can significantly reduce power consumption and extend battery life. Devices with low battery power can request to act as a target device instead of an initiator in passive mode.
In active mode, each device must generate its own RF field when it wants to send data to the other device. This is the standard mode for peer-to-peer communication and allows for very fast connection setup.
2.2.3 NFC Applications
NFC technology applications can be divided into four basic categories:
(1) Touch and Go, such as access control, tickets and entrance tickets, etc. Users only need to bring the mobile device storing the ticket or door control password close to the reading device.
(2) Touch and Confirm, such as mobile payment, the user confirms the transaction by entering a password or simply accepting the transaction.
(3) Touch and Connect, such as connecting two devices with built-in NFC to perform point-to-point data transmission, such as downloading music, transferring pictures and synchronizing address books.
(4) Touch and Explore: NFC devices can provide more than one useful function. Consumers will be able to understand what functions and services are provided by browsing an NFC device.
2.3 Bluetooth
2.3.1 Origin
The name Bluetooth comes from the 10th century Danish king Harald Blatand - English translation is Harold Bluetooth (because he loved to eat blueberries, so his teeth were blue every day). He unified Sweden, Finland and Denmark at that time. Naming this new technical standard after him implies unifying the fragmented situation.
In May 1998, five well-known manufacturers including Ericsson, Nokia, Toshiba, IBM and Intel proposed Bluetooth technology when jointly carrying out standardization activities for short-range wireless communication technology. Its purpose is to provide a short-range, low-cost wireless transmission application technology.
2.3.2 Specifications and Features of Bluetooth Technology
Bluetooth technology is an open global standard for wireless data and voice communications. It operates in the globally used 2.4GHz ISM (industrial, scientific, and medical) frequency band. The standard is IEEE802.15, which operates in the 2.4GHz frequency band with a bandwidth of 1Mb/s.
It is based on low-cost short-range wireless connection to establish a special connection for fixed and mobile device communication environment. Full-duplex communication is carried out in time division mode, and its baseband protocol is a combination of circuit switching and packet switching. A synchronous packet is sent on a frequency hopping frequency, and each packet occupies a time slot. It can also be expanded to 5 time slots using spread spectrum technology. At the same time, Bluetooth technology supports 1 asynchronous data channel or 3 concurrent synchronous voice channels, or 1 channel that transmits asynchronous data and synchronous voice at the same time. Each voice channel supports 64kb/s synchronous voice; asynchronous channels support asymmetric connections with a maximum rate of 721kb/s and a reverse response rate of 57.6 kb/s, or symmetrical connections with a maximum rate of 432.6 kb/s.
There are three distance levels for Bluetooth transmission, depending on the transmission output power:
Class 1 is about 100m;
Class 2 is about 10m;
Class 3 is about 2-3m.
Generally speaking, its normal working range is within a radius of 10m, within which multiple devices can be interconnected.
2.3.3 Bluetooth version
At present, Bluetooth has developed to Bluetooth 5.0:
The following is a detailed introduction to the features of the main versions of Bluetooth technology at this stage:
1. Version 1.1
The transmission rate is about 748~810kb/s. Because it is an early design, it is easily interfered by similar communication products at the same frequency, affecting the communication quality. This initial version supports the transmission requirements of stereo sound effects, but can only work in (simplex) mode. In addition, the bandwidth frequency response and other indicators are not ideal, so it is not the best stereo transmission tool.
Version 1.2
The transmission rate is also only 748~810kb/s, but the anti-interference frequency hopping function is added (software improvement). It supports the transmission requirements of stereo sound effects, but can only work in (simplex) mode. In addition, the bandwidth frequency response is still not ideal, and it cannot be used as a stereo transmission tool.
Version 2.0
2.0 is an improved version of 1.2, with a transmission rate of about 1.8M/s~2.1M/s, and can work in a (duplex) mode. That is, voice communication can be carried out while files/high-quality pictures can be transmitted. Of course, the 2.0 version also supports stereo operation. Subsequently, the Bluetooth 2.0 version chip added a stereo decoding chip, so even A2DP (Advanced Audio Distribution Profile) is no longer needed.
Version 2.1
In order to improve the problems of Bluetooth technology, the Bluetooth SIG (Special Interest Group) launched the Bluetooth 2.1+EDR version of Bluetooth technology. Improved device pairing process: In the past, a personal identification code was required to ensure the security of the connection during the connection process, but the improved connection method will automatically use a digital password for pairing and connection. For example, as long as you choose to connect a specific device in the phone options, after confirmation, the phone will automatically list the devices that can be used in the current environment and automatically connect; and in terms of short-distance pairing: it also has an NFC (Near Field Communication) mechanism for pairing and communication transmission between two Bluetooth-enabled mobile phones; better power saving effect: Bluetooth 2.1 version adds the SniffSubrating function, which saves power by setting the interval for sending signals to confirm each other between two devices. Bluetooth 2.1 extends the time interval for sending signals to confirm each other between devices from 0.1 seconds in the old version to about 0.5 seconds, which can greatly reduce the workload of the Bluetooth chip and allow Bluetooth to have more time to sleep completely. According to official reports, after adopting this technology, the standby time of Bluetooth devices after turning on Bluetooth connection can be effectively extended by more than 5 times, and full-duplex communication mode can be supported.
5. Version 3.0+HS
On April 21, 2009, the Bluetooth Special Interest Group (Bluetooth SIG) officially promulgated the new generation standard specification "Bluetooth Core Specification Version 3.0 High Speed". The core of Bluetooth 3.0 is "Generic Alternate MAC/PHY" (AMP), which is a new alternate radio frequency technology that allows the Bluetooth protocol stack to dynamically select the correct radio frequency for any task. The technologies that were originally expected to be used in the new specification included 802.11 and UMB, but the application of UMB was cancelled in the new specification. As a new version of the specification, the transmission speed of Bluetooth 3.0 will naturally be higher, and the secret lies in the 802.11 wireless protocol. By integrating "802.11 PAL" (protocol adaptation layer), the data transmission rate of Bluetooth 3.0 has been increased to about 24Mbps (that is, 802.11 WI-FI can be called when needed to achieve high-speed data transmission), which is eight times that of Bluetooth 2.0, and can be easily used for data transmission between video recorders to high-definition TVs, PCs to PMPs, and UMPCs to printers. In terms of power consumption, high-speed transmission of large amounts of data via Bluetooth 3.0 will naturally consume more energy, but due to the introduction of the Enhanced Power Control (EPC) mechanism, supplemented by 802.11, the actual idle power consumption will be significantly reduced, and the standby power consumption problem of Bluetooth devices is expected to be initially solved. In addition, the new specification also has two technologies, General Test Method (GTM) and One-Way Broadcast Unconnected Data (UCD), and includes a set of HCI instructions to obtain the key length. It is said that PCs equipped with Bluetooth 2.1 modules can theoretically make Bluetooth 2.1 devices support Bluetooth 3.0 by upgrading the firmware. Alliance members have begun to develop Bluetooth 3.0 solutions for device manufacturers.
6. Bluetooth 4.0
(1) Introduction
Bluetooth 4.0 is the upgraded standard of Bluetooth 3.0. The most important feature of Bluetooth 4.0 is power saving. The extremely low power consumption in operation and standby mode can make a button battery work continuously for several years. In addition, with many features such as low cost and cross-manufacturer interoperability, 3 millisecond low latency, AES-128 encryption, etc., it can be used in many fields such as pedometers, heart rate monitors, smart meters, sensor Internet of Things, etc., greatly expanding the application scope of Bluetooth technology.
(2) Main features
Bluetooth 4.0 is a supplement to the Bluetooth 3.0+HS specification. It is specifically designed for wireless solutions with high requirements on cost and power consumption. It can be widely used in many fields such as health care, sports and fitness, home entertainment, and security. It supports two deployment modes: dual mode and single mode. In dual mode, the low-power Bluetooth function is integrated into the existing classic Bluetooth controller, or a low-power stack is added to the existing classic Bluetooth technology (2.1+EDR/3.0+HS) chip. The overall architecture remains basically unchanged, so the cost increase is limited.
Single mode can only transmit with BT4.0 and is not backward compatible (cannot communicate with 3.0/2.1/2.0); Dual mode is backward compatible and can transmit with BT4.0 and 3.0/2.1/2.0. Single mode is aimed at highly integrated and compact devices, using a lightweight link layer (Link Layer) to provide ultra-low power standby mode operation, simple device recovery and reliable point-to-multipoint data transmission. It also allows networked sensors to arrange the order of low-power Bluetooth traffic in Bluetooth transmission, while also having advanced energy saving and secure encrypted connections.
(3) Advantages
Bluetooth 4.0 integrates three specifications, including traditional Bluetooth technology, high-speed technology and low-energy technology. The biggest difference compared to version 3.0 is low power consumption. "The power consumption of version 4.0 is 90% lower than that of the old version, which is more power-saving. "As Bluetooth technology expands from traditional application areas such as mobile phones, games, headphones, portable computers and automobiles to new areas such as the Internet of Things and medical care, the requirements for low power consumption will become higher and higher. Version 4.0 strengthens the low power consumption performance of Bluetooth in data transmission."
7. Bluetooth 4.1
(1) Introduction
If the main feature of Bluetooth 4.0 is power saving, then the keyword of this upgrade of Bluetooth 4.1 should be IOT (Internet of Things), which means connecting all devices to the Internet. In order to achieve this, the improvement of communication function is one of the most important improvements of Bluetooth 4.1.
(2) Main features
1) Bulk data transmission speed
The first thing to be affected is the transmission speed of bulk data. As we all know, the transmission rate of Bluetooth has always been very poor, and there is no comparison with Wi-Fi, which has already entered the gigabit era. Therefore, Bluetooth 4.1 has been upgraded on the basis of the widely used Bluetooth 4.0 LE, so that bulk data can be transmitted at a higher rate. Of course, this does not mean that Bluetooth can be used to transmit streaming video at high speed. This improvement is mainly aimed at wearable devices that have just emerged. For example, the data stream sent by the already common health bracelet is not large. Through Bluetooth 4.1, the information collected during running, swimming, and cycling can be transmitted to mobile phones and other devices more quickly, so that users can better monitor the status of exercise in real time, which is very useful. In the Bluetooth 4.0 era, all devices using Bluetooth 4.0 LE are labeled with "Bluetooth Smart" and "Bluetooth SmartReady". Among them, Bluetooth Smart Ready devices refer to connection center devices such as PCs, tablets, and mobile phones, while Bluetooth Smart devices refer to Bluetooth headsets, keyboards, mice and other expansion devices. Previously, the roles between these devices had been arranged long ago, and they could not be interchanged, and could only be connected one to one. Bluetooth 4.1 technology allows devices to act as both "Bluetooth Smart" and "Bluetooth Smart Ready" at the same time, which means that multiple devices can be connected to one Bluetooth device. For example, a smart watch can be used as a central hub to receive exercise information collected from a health bracelet, and can also be used as a display device to display emails and text messages from a smartphone. With the help of Bluetooth 4.1 technology, smart watches, smart glasses and other devices can become real central hubs.
2) Connect to the Internet via IPV6
In addition, the problem of wearable devices not being able to access the Internet can also be solved by Bluetooth 4.1. The new standard adds a dedicated channel to allow devices to be used online via IPv6. For example, if a Bluetooth device cannot access the Internet, then after connecting to an Internet-enabled device via Bluetooth 4.1, the device can directly connect to the Internet using IPv6 and achieve the same functions as WiFi. Although the Internet applications of this device are limited due to the transmission rate, operations such as synchronizing data and sending and receiving emails are still fully achievable. The advantage of this improvement is that sensors and embedded devices only need Bluetooth to connect to mobile phones and the Internet. Relatively speaking, WiFi is mostly used to connect to the Internet and is generally not effective in connecting devices, and cannot achieve the functions of Bluetooth. In the future, as the Internet of Things gradually enters our lives, the status of wireless transmission in daily life will become higher and higher. As the most widely used transmission method, Bluetooth will play an important role in the "Internet of Things". However, it will take a longer time for Bluetooth to fully adapt to IPv6, so it depends on how chip manufacturers can help Bluetooth devices increase IPv6 compatibility.
3) Simplify device connections
Driven by major mobile phone manufacturers and PC manufacturers, almost all mobile devices and laptops are equipped with Bluetooth modules, and users use Bluetooth more frequently. However, there are still a large number of users who find Bluetooth very troublesome to use. In the final analysis, it is caused by the more complicated pairing and connection of Bluetooth devices. Imagine if a smart watch connected to a mobile phone has to be manually selected once in the settings interface to reconnect every time it is disconnected, which is very troublesome. The previous solution to this problem was for manufacturers to add NFC chips to both Bluetooth devices, and simplify the re-pairing steps through NFC near-field communication, which was a good idea. It’s just that products equipped with NFC chips are not only few in number, but also expensive, and very niche.
Bluetooth 4.1 has made improvements to this point, and has made significant changes to the connection and reconnection between devices, which can provide manufacturers with more design permissions during design, including setting the frequency band to create or maintain Bluetooth connections. This change has significantly improved the flexibility of Bluetooth device connections. Two devices with Bluetooth 4.1 have been successfully paired before. When reconnecting, just bring the two devices close together to reconnect, and no manual operation is required. For example, when using Bluetooth 4.1 headphones in the future, just turn on the power switch, and there is no need to operate on the phone. It is very simple.
4) Peaceful coexistence with 4G
In the field of mobile communications, the hottest topic recently is 4G, which has become an irreversible development trend of the global wireless communication network. Bluetooth 4.1 is also optimized specifically for 4G to ensure that it can coexist peacefully with 4G signals. This improvement is called "coexistence" by the Bluetooth Technology Alliance. You may wonder why Bluetooth 4.1 has to make special improvements to this point, haven't mobile network signals and Bluetooth coexisted for a long time? This is because in actual applications, if the two transmit data at the same time, Bluetooth communication may be interfered by mobile network signals, resulting in a decrease in transmission rate. Therefore, in the new Bluetooth 4.1 standard, once Bluetooth 4.1 and 4G networks are transmitting data at the same time, Bluetooth 4.1 will automatically coordinate the transmission information of the two, thereby reducing the interference of other signals on Bluetooth 4.1, and users do not have to worry about the problem of reduced transmission rate.
5) Enhanced features provided by Bluetooth 4.1
include:
AES encryption technology provides a more secure connection. This feature makes wireless headphones more suitable for security-critical applications such as government, medical and banking.
Headphones, speakers and sound bars can be controlled via a dedicated Bluetooth Smart remote control, and support simultaneous playback of audio streams from a completely different device.
8. Bluetooth 4.2 Standard
On December 4, 2014, the Bluetooth 4.2 standard was promulgated, which improved data transmission speed and privacy protection, and can directly access the Internet through IPv6 and 6LoWPAN. Under the new standard, Bluetooth signals must obtain user permission to connect or track user devices, otherwise Bluetooth signals will not be able to connect and track user devices.
The data transmission speed between two Bluetooth devices has become faster, increasing by 2.5 times, because the capacity of Bluetooth Smart data packets has increased, and the amount of data that can be accommodated is about 10 times that of before.
9. Bluetooth 5.0 Protocol
Officially released in London on June 16, 2016 (US time), it is the most advanced Bluetooth protocol standard at this stage. Bluetooth 5.0 has the following features:
(1) Faster transmission speed
Bluetooth 5.0 developers claim that the new version of Bluetooth transmission speed is capped at 2Mbps, twice as fast as the previous 4.2LE version. Of course, you are unlikely to reach this limit in real life, but you can still experience a significant speed increase.
(2) Longer effective distance
Another important improvement of Bluetooth 5.0 is that its effective distance is four times that of the previous version, so in theory, when you stand 300 meters away from the Bluetooth speaker with your phone, it will continue to play your favorite songs. In other words, in theory, the effective working distance between Bluetooth transmitting and receiving devices can reach 300 meters. Of course, the actual effective distance also depends on the electronic device you use.
(3) Navigation function
Bluetooth 5.0 will add more navigation features, so the technology can be used as an indoor navigation beacon or similar positioning device, and combined with Wi-Fi, it can achieve indoor positioning with an accuracy of less than 1 meter. For example, if you are a person with poor direction, you can still use Bluetooth technology to find your way in a large commercial center.
(4) Internet of Things Function
The Internet of Things continues to be popular, so Bluetooth 5.0 has made many underlying optimizations for the Internet of Things, striving to serve smart homes with lower power consumption and higher performance.
(5) Upgrade hardware
Some previous Bluetooth version updates only required software upgrades, but Bluetooth 5.0 will likely require an upgrade to a new chip. However, old hardware will still be compatible with Bluetooth 5.0, but you won't be able to enjoy its new features. Flagship phones equipped with Bluetooth 5.0 chips will be available in 2017, and I believe that mid- and low-end phones will also have built-in Bluetooth 5 chips one after another. Apple will be one of the first manufacturers to use this technology.
(6) More transmission functions
The new Bluetooth 5.0 can add more data transmission functions, and hardware manufacturers can use Bluetooth 5.0 to create more complex connection systems, such as Beacon or location services. Therefore, the advertising data sent by the Bluetooth device can send a small amount of information to the target device without even pairing.
(7) Lower power consumption
As we all know, Bluetooth is a must-have feature of smartphones. As more and more smart devices and mobile payments require Bluetooth to be turned on to enjoy convenient functions, Bluetooth power consumption has become a major killer of smartphone standby time. Therefore, Bluetooth 5.0 will greatly reduce the power consumption of Bluetooth, so that people no longer have to worry about the short standby time when using Bluetooth.
(8) Truly support lossless transmission
It supports 24bit/192KHz lossless audio source transmission, posing an effective threat to existing Wi-Fi high-fidelity lossless audio transmission.
2.3.4 Bluetooth matching rules
Before two Bluetooth devices can communicate, they must be matched together to ensure that the data information sent by one device will only be received by the other device with permission. Bluetooth technology divides devices into two types: master devices and slave devices.
(1) Bluetooth master device
The main device generally has an input terminal. When performing a Bluetooth matching operation, a user can enter a random matching password through the input terminal to match two devices.
Bluetooth mobile phones, PCs with Bluetooth modules installed, etc. are all master devices. (For example, when a Bluetooth mobile phone and a Bluetooth PC are paired, the user can enter a set of numbers on the Bluetooth mobile phone, and then enter the same set of numbers on the Bluetooth PC to complete the pairing between the two devices.)
(2) Bluetooth slave device
Slave devices generally do not have input terminals. Therefore, when a slave device leaves the factory, a 4-digit or 6-digit matching password is fixed in its Bluetooth chip. Bluetooth headsets, UD digital pens, etc. are all slave devices. (For example: when a Bluetooth PC is paired with a UD digital pen, the user correctly enters the Bluetooth matching password on the UD pen into the Bluetooth PC to complete the matching between the UD pen and the Bluetooth PC.)
Note:
Master devices and slave devices can be matched with each other, but slave devices cannot be matched with each other.
For example: a Bluetooth PC can be matched with a Bluetooth mobile phone; a Bluetooth PC can also be matched with a UD pen; but UD pens cannot be matched with each other.
A main device can match one or more other devices. For example, a Bluetooth mobile phone can generally only match 7 Bluetooth devices. However, a Bluetooth PC can match more than ten or even dozens of Bluetooth devices.
At the same time, only point-to-point communication is supported between Bluetooth devices.
2.3.5 Bluetooth Applications
Bluetooth technology can be applied to all aspects of daily life. For example, by introducing Bluetooth technology, the annoying connection cable between mobile phones and laptops can be removed and communication can be established wirelessly.
Printers, PDAs, desktop computers, fax machines, keyboards, game joysticks and all other digital devices can become part of the Bluetooth system.
3 Long-range cellular communication protocols
Long-distance cellular communication protocols are mainly the standards and protocols adopted by various telecom operators under 2/3/4/5G, NB-IoT and other technologies. We will not further advocate for telecom operators and large equipment manufacturers here.
4 Long-range non-cellular communication protocols
4.1 ZigBee
4.1.1 Introduction to ZigBee
The name ZigBee comes from the communication method of bee colonies: bees exchange messages by dancing in a zigzag shape to share information such as the direction, location and distance of food sources. Zigbee is thus named as a new generation of wireless communication technology.
ZigBee is a highly reliable wireless data transmission network, similar to CDMA and GSM networks. ZigBee data transmission modules are similar to mobile network base stations. ZigBee is a wireless network platform composed of up to 65,000 wireless data transmission modules. Within the entire network, each network module can communicate with each other, and the distance between each network node can be infinitely extended from the standard 75m. The communication distance ranges from the standard 75m to hundreds of meters and kilometers, and supports unlimited expansion (depending on the increase in the number of nodes). Unlike the CDMA network or GSM network of mobile communications, the ZigBee network is mainly established for industrial field automation control data transmission. Therefore, it must be simple, easy to use, reliable, and low-priced. The mobile communication network is mainly established for voice communication, and each base station is generally worth hundreds of thousands or even millions of RMB, while each ZigBee network "base station" (node) is less than 1,000 RMB.
4.1.2 Technical Features
ZigBee is a wireless connection that can operate in three frequency bands: 2.4GHz (popular worldwide), 868MHz (popular in Europe) and 915 MHz (popular in the United States), with a maximum transmission rate of 250kbit/s, 20kbit/s and 40kbit/s respectively. Its transmission distance is within the range of 10-75m, but can be further increased.
As a wireless communication technology, ZigBee has the following characteristics:
(1) Low power consumption
(2) Low cost
(3) Short delay
(4) Large network capacity
(5) Reliability
(6) Safety
4.1.3 ZigBee Protocol Stack
The ZigBee protocol stack structure is based on the standard OSI seven-layer model, including high-level application specifications, application convergence layer, network layer, media access layer and physical layer.
IEEE 802.15.4 defines two physical layer standards, namely the 2.4 GHz physical layer and the 868/915 MHz physical layer, both of which are based on direct sequence spread spectrum (DSSS) technology.
868MHz has only one channel with a transmission rate of 20kb/s; 902MHz~928MHZ has 10 channels with a channel spacing of 2MHz and a transmission rate of 40kb/s. Both of these frequency bands use BPSK modulation.
The 2.4GHz~2.4835 GHz frequency band has 16 channels with a channel spacing of 5MHz, which can provide a transmission rate of 250kb/s and adopts O-QPSK modulation.
To improve the reliability of data transmission, the media access control (MAC) layer defined by IEEE 802.15.4 adopts CSMA-CA and slotted CSMA-CA channel access methods and a full handshake protocol.
The application convergence layer is mainly responsible for mapping different applications to the ZigBee network, mainly including security and authentication, convergence of multiple business data streams, device discovery and business discovery.
4.1.4 Application areas
(1) Automation control of homes and buildings: remote control of lighting, air conditioning, curtains and other furniture equipment;
(2) Consumer electronic devices: remote control of televisions, DVD players, CD players and other electrical appliances.
(3) PC peripherals: wireless keyboard, mouse, game joystick, etc.;
(4) Industrial control: making it easier to automatically collect, analyze and process data;
(5) Medical equipment control: medical sensors, patient emergency call buttons, etc.;
(6) Interactive toys.
4.2 LoRa
LoRa (Long Range) is a modulation technology that provides a longer communication distance than similar technologies. Since LoRa modulation is a physical layer (PHY), it can also be used for different protocols and different network architectures (such as Mesh, Star, point-to-point, etc.). LoRa can be summarized as the following protocols:
(1) LoRaWAN protocol
(2) CLAA Network Protocol
(3) LoRa private network protocol
(4) LoRa data transparent transmission
LoRa's protocols are different, and its products and business forms are also different.
4.2.1 LoRaWAN Protocol
The LoRaWAN protocol is a low-power wide area network protocol promoted by the LoRa Alliance, which is optimized for low-cost, battery-powered sensors, including different categories of nodes, optimizing network latency and battery life. The LoRa Alliance standardized LoRaWAN to ensure that LoRa networks in different countries are interoperable.
LoRaWAN builds a large network at the operator level, covering the region and even the whole country. After several years of development, a relatively complete ecological chain has been established: LoRa chip → module → sensor → base station or gateway → network service → application service.
In terms of chips, Semtech has authorized many companies to make chips, such as ST, Micorochip, Huapu, etc., making chip products more abundant, with multiple sources for one chip, and products are no longer restricted to one supplier. In the future, more manufacturers may be authorized to produce products that meet the diverse needs of the IoT market.
Before the LoRaWAN network was deployed, modules that conform to the LoRaWAN protocol could not be freely sold like 2G/3G/4G modules. Generally, LoRaWAN modules are sold together with gateways or base stations. Some manufacturers have also opened up the terminal part and provided solutions for the gateway and network service parts.
Among LoRaWAN products, most manufacturers mainly provide (cloud) end-to-end solutions, including modules, gateways and network servers, such as NPLINK, August Technology, Holley, Weichuan, Mensi, Future Broadband, etc. Due to different requirements for device data, some LoRaWAN network services (NS) are privately deployed, while others are deployed on public clouds or third-party network servers.
LoRaWAN is currently mainly aimed at the toB market and has not yet been popularized in the toC market. Some companies with industry or market resources will deploy LoRaWAN networks early to change existing or create new application systems, and the innovative vitality of the low-power wide area network market also lies in this.
4.2.2 CLAA Agreement
"The China Lora Application Alliance (CLAA) is a technical alliance initiated by ZTE with the support of the LoRa Alliance and widely participated and co-built by IoT application innovation entities in various industries. It aims to jointly establish a Chinese LoRa application cooperation ecosystem, promote the application and development of the LoRa industry chain in China, and build a multi-service sharing, low-cost, wide-coverage, and operational LoRa Internet of Things. As a member of the board of directors of the LoRa Alliance (LoRa Alliance for short), ZTE works with LoRa Alliance members to promote the construction of LoRa technology in the global low-power wide-area network (LPWAN) and the development of the industry chain."
ZTE has optimized the protocol based on LoRaWAN and built a co-built and shared LoRa application platform. With ZTE's strength and influence in the industry, many companies' products have been gathered on the CLAA platform. CLAA provides gateway and cloud core network services, which can quickly build the application of the LoRa network IoT system.
CLAA has four main business cooperation models:
(1) Independent operator: Provide a full range of solutions; support customers in building networks and share IoT interconnection with CLAA
(2) Large partners: Direct equity participation, CLAA is responsible for network construction, covering multiple cities and enjoying the overall benefits of the entire network, and CLAA bears the operation and maintenance costs
(3) Small and medium-sized customers: Directly purchase equipment, CLAA assists in network construction, city-level or regional-level coverage, enjoy city-level or regional-level benefits, and customers bear the operation and maintenance costs
(4) Professional channel providers: directly purchase equipment, build micro-customer networks on their own, assist customers in operations, and customers bear the operation and maintenance costs
4.2.3 LoRa Private Network Protocol
In applications with a small number of nodes in a small area, the cost of deploying a network using a LoRaWAN gateway is high. Use one or several SX127x as a small "gateway" or "concentrator", wirelessly connect hundreds of SX127x, form a small star network, and use your own LoRa private communication protocol to implement a simple LoRa private network. This is also a more flexible way. Of course, the protocol can also be the LoRaWAN protocol.
4.2.4 LoRa data transparent transmission
Currently, the LoRa chips on the market are basically derived from the SX127x series of SEMTECH in the United States. LoRa is used to make a transparent transmission module, which only performs simple sending and receiving to achieve point-to-point data transmission, and the application is relatively simple.
5 Wired Communication Protocol
5.1 USB Protocol
Currently, USB has developed three generations of protocols:
USB protocol specification 1.1——support USB low-speed and full-speed specifications (12Mbps)
USB protocol specification 2.0——Support USB high-speed protocol specification (480Mbps)
USB protocol specification 3.0——support USB super-speed protocol specification (5Gbps)
USB 3.0 is the latest USB specification, which was initiated by Intel and other companies. USB 2.0 has been generally recognized by PC manufacturers, and the interface has become a must-have interface for hardware manufacturers. The maximum transmission bandwidth of USB 2.0 is 480Mbps (60MB/s), while the maximum transmission bandwidth of USB 3.0 is as high as 5.0Gbps (i.e. 640MB/s). However, please note that this is a theoretical transmission value. If several devices share a USB channel, the main control chip will allocate and control the bandwidth available to each device. For example, in USB 1.1, all devices can only share 1.5MB/s of bandwidth. If a single device occupies all the bandwidth of the USB interface, it will cause difficulties for other devices to use.
5.2 RS232 Protocol
RS232 is an asynchronous transmission standard interface protocol. Usually the RS-232 interface appears in the form of 9 pins (DB-9) or 25 pins (DB-25). The most common connection method of RS232 is three wires: a send line, a receive line and a ground line.
Level signal: logic 1 (MARK) = -3V ~ -15V, logic 0 (SPACE) = +3 ~ +15V
Transmission distance: RS-232-C standard stipulates that the driver is allowed to have a 2500pF capacitance load, and the communication distance will be limited by this capacitance. For example, when using a 150pF/m communication cable, the maximum communication distance is 15m; if the capacitance per meter of cable is reduced, the communication distance can be increased. Another reason for the short transmission distance is that RS-232 is a single-ended signal transmission, which has problems such as common ground noise and inability to suppress common mode interference (the signals on the two transmission lines become larger or smaller at the same time), so it is generally used for communication within 20m.
RS232 cannot realize multi-machine communication.
Transmission rate: The transmission rate of RS232 is slow, and there are relatively few that can reach 1Mbps.
5.3 RS485 Protocol
RS485 is an upgraded version of RS232 serial port protocol, which generally adopts two-wire transmission: A and B transmission lines.
Level signal: -2V~-6V represents "0", +2V~+6V represents "1", and the voltage is the voltage of AB.
Transmission distance: Generally, there is no problem within 1 km. Theoretically, when the communication rate is 100Kpbs or below, the maximum transmission distance of RS485 can reach 1200 meters, but in actual applications, the transmission distance varies due to the transmission characteristics of the chip and cable. During the transmission process, the signal can be amplified by adding relays, and up to eight relays can be added, which means that the maximum transmission distance of RS485 can reach 9.6 kilometers in theory. If long-distance transmission is really needed, optical fiber can be used as the transmission medium, and an optoelectronic converter can be added at both ends of the transmitter and receiver. The transmission distance of multi-mode optical fiber is 5~10 kilometers, while the transmission distance of single-mode optical fiber can reach 50 kilometers.
RS485 can realize multi-machine communication.
Reason: RS485 is a half-duplex communication mode, that is, receiving and sending are realized in time-sharing. When the bus is idle, it is necessary to ensure that the state is logic 1, that is, the voltage of AB meets the level value of logic 1. Assume that 1 is the host, 2 and 3 are slaves, and the data line connection method is that A of 1, 2, and 3 are connected together, and B of 1, 2, and 3 are also connected together. There is no problem with the RS232 connection method.
Asynchronous Transmission: Asynchronous transmission divides bits into small groups for transmission. The group can be 1 character of 8 bits or longer. The sender can send these bit groups at any time, and the receiver never knows when they will arrive. A common example is the communication between a computer keyboard and a host computer.
Baud rate calculation: If the baud rate is set to 115200, the data bit is 8 bits, the start bit is 1 bit, the end bit is 1 bit, and the check bit is 1 bit; then the characters that can be transmitted continuously in 1 second (1 bit start bit + 8 bits data bit + 1 bit check bit + 1 bit end bit, a total of 11 bits) are 115200/11=10472; 10472/1024 is about 10.227, so the rate is about 10kB/ps.
5.4 M-Bus Protocol
M-BUS will not be introduced in this article, because the author will share the remote meter reading system in subsequent articles, and M-Bus was created for data collection in the remote meter reading system. In the remote meter reading system, the author will analyze the M-Bus protocol.
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