The concept of "Internet of Things" was first put forward by the Massachusetts Institute of Technology in 1999. In a narrow sense, the Internet of Things refers to "Internet connected by things", where the connected subjects include not only things to things, but also things to identification and management equipment.
The Internet of Things in a broad sense refers to the integration of information space and physical space, that is, the integration of virtual and reality. All objects and events are digitized and networked, and information interaction is realized between people, people and things, and things and things, and automatic identification, monitoring and positioning and remote management of items are realized. Based on the existing Internet and various proprietary networks, the Internet of Things transmits all kinds of data collected and summarized through the perception layer to realize real-time data transmission and ensure data security.
At present, wired and wireless Internet, 2G and 3G networks, etc. can all be used as components of the transport layer. In the future when the terminals of Internet of Things such as smart community and smart home are popular, in order to ensure the security of wireless data transmission, wireless transmission protocol is particularly important.
Let’s take a look at the common types of wireless transmission protocols in the Internet of Things:
RFID
RFID(Radio Frequency
Identification), namely radio frequency identification, commonly known as electronic tag. It is a non-contact automatic identification technology, which automatically identifies the target object through radio frequency signals and obtains relevant data.
RFID consists of three basic elements: Tag, Reader and Antenna. The basic working principle of RFID technology is not complicated. After the tag enters the magnetic field, it receives the RF signal sent by the reader and sends out the product information (Passive) stored in the chip with the energy obtained by the induced current.
Tag, passive tag or passive tag), or Actively send a signal of a certain frequency (active
Tag (active tag or active tag), the reader reads and decodes the information and sends it to the central information system for data processing.
RFID can be widely used in security and anti-counterfeiting, industrial and commercial automation, property protection, logistics, vehicle tracking, parking lots and highway toll collection systems. In terms of industry, RFID will penetrate into various fields including automobile, medicine, food, transportation, energy, military industry, animal management and personnel management.
infrared
Infrared technology is also a kind of wireless communication technology, which can transmit wireless data. Infrared has obvious characteristics: point-to-point transmission mode, wireless, not too far away, aiming at the direction, not passing through walls and obstacles, and almost unable to control the progress of information transmission. In the 802.11 physical layer standard, in addition to using 2.4GHz radio frequency, it also includes infrared related standards. IrDA1.0 supports a communication rate of up to 115.2kbps, and IrDA1.1 supports 4Mbps. This technology has basically been eliminated and replaced by Bluetooth and newer technologies.
ZigBee
ZigBee is a new wireless network technology with short distance, low power consumption and low speed. ZigBee
The foundation of is IEEE802.15.4, which is a standard of IEEE Wireless Personal Area Working Group. However, IEEE802.15.4 only deals with low-level MAC layer and physical layer protocols, so the ZigBee alliance has standardized its network layer and API, and the alliance is also responsible for its security protocols, application documents and marketing.
ZigBee Alliance was established in August 2001, and consists of British Invensys, Japanese Mitsubishi Electric, American Motorola, Dutch Philips Semiconductor and other companies. ZigBee and Bluetooth
(Bluetooth) and WiFi (Wireless Local Area Network) are both IEEE standard network protocols in 2.4GHz band, and their applications are different due to their different performance positioning.
ZigBee has remarkable characteristics: ultra-low power consumption, large network capacity, reliable data transmission, short time delay, good security and low implementation cost. In ZigBee technology, the security mechanism of symmetric key is adopted, and the key is generated by the network layer and the application layer according to the actual application needs, and managed, stored, transmitted and updated. Therefore, in the future Internet of Things, ZigBee technology is particularly important, and has been widely used in the field of Internet of Things such as smart home in the United States.
Bluetooth
Bluetooth is a technical standard jointly put forward by Toshiba, Ericsson, IBM, Intel and Nokia in May 1998. As an open global specification for wireless data and voice communication, Bluetooth establishes a special connection for fixed and mobile communication environment based on low-cost short-range wireless connection, and completes short-range wireless transmission of data information. Its essence is to establish a universal Radio air interface (Radio
Air
Interface) and the open standard of its control software further combine communication with computers, so that portable devices produced by different manufacturers can have Interoperability in a short range without wires or cables.
Bluetooth is based on IEEE802.11 standard technology of wireless LANs. The concept of "Plonkandplay" (somewhat similar to "plug and play") is applied, that is, once any Bluetooth device searches for another Bluetooth device, it can establish contact immediately without any setting by the user, so it can be interpreted as "instant play".
Bluetooth technology has the characteristics of low cost, low power consumption, small size, short-range communication and good security. Bluetooth will be applied in the future development of the Internet of Things, especially in the office, smart home and other environments.
GPRS
General Packet Radio technology (GPRS)
Service, GPRS), using packet switching mode with mobility management and wireless access technology. GPRS is a continuation of GSM. GPRS is different from the way of continuous channel transmission in the past, and it is transmitted in the form of Packet, so the cost borne by users is calculated based on the data transmission unit, rather than using the whole channel, which is cheaper in theory. The transmission rate of GPRS can be increased to 56 or even 114Kbps. But GPRS technology is not suitable for smart home, and it is mainly used in telecommunication network.
3G
The third generation mobile communication technology (3G) refers to the cellular mobile communication technology that supports high-speed data transmission. 3G service can transmit voice and data information at the same time, and the rate is generally above several hundred kbps.
At present, there are four 3G standards: CDMA2000 (American version), WCDMA (European version), TD-SCDMA (China version) and WiMAX. In May, 2000, the International Telecommunication Union (ITU) determined three mainstream wireless interface standards: WCDMA, CDMA2000 and TD-SCDMA, which were written into the 3G technical guidance document "International Mobile Communication Plan 2000". In 2007, WiMAX was also accepted as one of the 3G standards.
CDMA is Code Division Multiple Access.
The abbreviation of Code Division Multiple Access is the technical basis of the third generation mobile communication system. The first generation of mobile communication system adopts frequency division multiple access (FDMA) analog modulation mode, but the main disadvantages of this system are low spectrum utilization and signaling interference with voice services.
The second generation mobile communication system mainly adopts time division multiple access (TDMA) digital modulation mode, which improves the system capacity, and uses independent channels to transmit signaling, which greatly improves the system performance, but the system capacity of TDMA is still limited and the handover performance is still not perfect. The CDMA system shows great development potential because of its simple frequency planning, large system capacity, high frequency reuse coefficient, strong anti-multipath ability, good communication quality, soft capacity and soft handover.
4G
4G technology is also called IMT-Advanced technology. Quasi-4G standard is the TD-LTE-Advanced title of the latest development of TD technology to 4G in the industry. There is not much disagreement in the industry about the core technologies to be used in 4G. To sum up, there are five technologies: orthogonal frequency division multiplexing (OFDM), software radio, smart antenna technology, multiple-input multiple-output (MIMO) technology and IP-based core network.
Because the initial purpose of people’s research on 4G communication is to improve the wireless access rate of cellular phones and other mobile devices to Inter, the most impressive feature of 4G communication is its faster wireless communication speed. In addition, 4G also has wide network spectrum, flexible communication and high intelligent performance.
Good compatibility and low cost.
4G communication technology is not perfect, mainly reflected in the following aspects: First, it is difficult to unify the technical standards of 4G communication technology. Second, the marketing of 4G communication technology is difficult to achieve. Third, the supporting facilities of 4G communication technology are difficult to update.
Wi-Fi
Wi-Fi is called Wireless Fidelity, also known as IEEE.
802.11b standard, its biggest advantage is its high transmission speed, which can reach 11Mb/s, and its effective distance is also very long, and it is also different from various existing IEEE 802.11 standards.
DSSS (Direct Sequence Spread Spectrum) equipment is compatible.
IEEE
802.11b wireless network specification is developed on the basis of IEEE802.11a network specification, and the maximum bandwidth is 11Mb/s, which can be adjusted to 5.5Mb/s, 2Mb/s and 1Mb/s in case of weak signal or interference. The automatic adjustment of bandwidth effectively ensures the stability and reliability of the network. Wi-Fi wireless fidelity technology, like Bluetooth technology, belongs to short-range wireless technology used in offices and homes. The frequency band used is around 2.4GHz, which is still a wireless frequency band without license. There are two standards that can be used, namely 802.11ay and 802.11b, and 802.11g is the inheritance of 802.11b..
Its main characteristics are: high speed and high reliability. In the open area, its communication distance can reach 305m m. In the closed area, the communication distance is 76 ~ 122 m, which is convenient to integrate with the existing wired Ethernet and the networking cost is lower.
NB-IoT
NB-IoT is narrow band-of-things (narrow band-of-things
Things), a kind of Internet of Things technology, has the characteristics of low cost, low power consumption, wide coverage, etc. It is positioned in the carrier-level low-rate Internet of Things market based on licensed spectrum and has broad application prospects. NB-IoT technology includes six main application scenarios, including location tracking, environmental monitoring, intelligent parking, remote meter reading, agriculture and animal husbandry. And these scenes are exactly the scenes that the existing mobile communication is difficult to support. Machina, a market research company, predicts that NB-IoT technology will cover 25% of Internet of Things connections in the future.
NB-IoT is 3GPP.
An important enhancement technology of R13 LTE, the RF bandwidth can be as low as 0.18MHz. NB-IoT is the fusion of NB-CIoT and NB-LTE standards, which balances the interests of all parties and is suitable for a wider range of deployment scenarios. Among them, Huawei, Vodafone, Qualcomm and other companies support NB-CIoT; Companies such as Ericsson, ZTE, Samsung, Intel and MTK support NB-LTE. Compared with the standard NB-IoT, NB-CIoT and NB-LTE are quite different, so the terminal cannot be upgraded smoothly, and some non-standard base stations even face the risk of quitting the network.
With the continuous development of Internet of Things technology and application, wireless transmission protocol will usher in unprecedented development, and its application in future intelligent systems will also show explosive growth. Understanding and mastering the core technologies such as ZigBee, Bluetooth, Wi-Fi and RFID, and developing the corresponding borrowing interface and modularization of wireless communication products are definitely the correct means for enterprises to create business opportunities. Wireless transmission protocol has always been a key technology in the development of the Internet of Things, and it will also be the top priority in the future development of the Internet of Things.