LoRa is one of LPWAN communication technologies, and it is an ultra-long-distance wireless transmission scheme based on bai spread spectrum technology adopted and popularized by Semtech Company of the United States. Physical layer or wireless modulation is used to establish long-distance communication links. Many traditional wireless systems use frequency shift keying (FSK) modulation as the physical layer because it is a very effective modulation to achieve low power consumption.
2、WiFi
The full name of Wireless-Fidelity is a standard in WLAN. Since 1999 was launched, it has been one of the most commonly used ways to surf the Internet in our life.
3.Zigbee/802.15.4 protocol
Zigbee was formally put forward in 2003, and its appearance made up for the shortcomings of Bluetooth communication protocol, such as high complexity, high power consumption, short distance and small networking scale. The name comes from bees. Bee is a kind of "dance", which transmits the position information of pollen to its companions by flying and flapping its wings, and forms a communication network in the group.
4. Thread /IEEE 802. 15.4 protocol
Thread and ZigBee belong to 802. 15.4, but they have been greatly improved. Thread is a protocol based on IPv6, which is optimized in transmission security and system reliability. It can not only carry AllSeen, the Internet of Things alliance of dozens of enterprise groups in Qualcomm Haier, but also support Apple's Homekit smart home platform.
5. Z-wave
Z-Wave wireless networking specification was put forward by Danish chip and software developer Zensys in 2004, and its application was promoted by Z-Wave Alliance. The working frequency of Z wave is 908.42MHz in the United States and 868.42MHz in Europe. It adopts wireless mesh network technology, so any node can directly or indirectly communicate with other neighboring nodes within the communication range.
Characteristics of wireless communication technology
First, wireless communication technology is not affected by time and space factors.
Wireless communication technology does not rely on antenna to transmit information, and its transmission medium is electromagnetic wave and light wave. Electromagnetic waves and light waves exist widely in the atmosphere, so their propagation will not be affected by propagation medium factors. In addition, wireless communication technology can also transmit information by means of satellite network. Pictures, short messages, videos, audio and other information can be spread through wireless communication technology with the help of satellite network, which greatly improves the efficiency of information dissemination.
This way of information exchange, which is not limited by time and space, greatly meets people's communication needs, solves the difficulties and problems in people's cross-regional communication, and improves the timeliness and convenience of information exchange and interaction. At the same time, excellent information processing ability is also a significant advantage of wireless communication technology, which can realize the rapid acquisition and processing of knowledge information and greatly facilitate people's lives.
Second, wireless communication technology is mobile.
After the birth of wireless communication technology, with the development of information technology, breakthrough innovation and progress have been made in technology. For example, in wireless communication technology terminals, it has been continuously improved. Wireless communication users can move between different areas, and their communication connections can also move accordingly, without any impact on communication signals.
At present, mobile intelligent terminal is the main tool and carrier for the application of wireless communication technology. Because of their small size, these tools are convenient for people to carry and are more conducive to wireless communication. Users can travel with these tools, and they can always maintain and have good communication skills. Users can do business or entertainment without time and space constraints.
Third, wireless communication is unstable.
Although wireless communication technology has many advantages and brought great convenience to people's lives, it still has some shortcomings. Wireless communication technology mainly relies on electromagnetic waves, light waves and other media in the air, and the atmosphere is the physical channel for wireless communication transmission. However, because the atmosphere is an open space, that is to say, when the information of wireless communication technology is spread, all the modulated information is exposed to public space, which has great security risks.
Due to the lack of corresponding physical layer protection during information transmission, some criminals can steal and tamper with information through this loophole, and the security of information cannot be effectively guaranteed. The instability of wireless communication technology will increase users' communication risks and hidden dangers, which will have a great adverse impact on personal privacy and the stability of the whole society.
Baidu encyclopedia-wireless communication