Language is the most important communication tool for human beings and the main expression for people to communicate. In the age of the Internet of Things, when machines need to communicate, they also need to be in a language that they can understand each other. Today, we will take a look at the wireless short-range communication languages ​​and technologies that are commonly used in the Internet of Things--Huawei Hilink protocol, WiFi (IEEE 802.11 protocol), Mesh, Bluetooth, ZigBee, Thread, Z-Wave, NFC, UWB, LiFi.
1. Huawei Hilink Agreement
In December last year, Huawei launched a self-developed "three-piece" smart home "Hilink", Huawei-LiteOS system and IOT chip. At present, various Internet end-user interconnection agreements on the market have been arbitrarily contested, but they seem to be unfriendly and isolated from each other, and each is behind closed doors. The Hilink protocol is known as the "mandarin" between smart devices. It automatically discovers devices and connects them with one click, and is compatible with protocols such as ZigBee, WiFi and Bluetooth.
2.WiFi/IEEE 802.11 protocol
WiFi, full name Wireless-Fidelity, wireless fidelity, is a standard in wireless local area networks (WLAN). Since its launch in 1999, it has been one of the more popular ways to access the Internet in our lives. Usually WiFi technology uses 2.4GHz and 5GHz surrounding frequency bands, and a wired router can connect a wired router to a WiFi signal. The WiFi standard family also has 802.11a, 802.11b, 802.11g, and 802.11n.
In 2016, the WiFi Alliance's latest 802.11ah WiFi standard, WiFi HaLow, enables WiFi to be used in more places such as small-size, battery-powered wearable devices that are also suitable for deployment in industrial facilities, and between Between applications. HaLow uses the 900MHz band, which is lower than the 2.4GHz and 5GHz bands of current WiFi. Lower power consumption, while HaLow's coverage can reach 1 km, the signal is stronger, and it is not easy to be disturbed. These characteristics make WiFi more responsive to the development of the Internet of Things era.
Advantages: wide coverage and fast data transfer rate.
Disadvantages: poor transmission security, poor stability, slightly higher power consumption, and poor networking capabilities.
3.Mesh/IEEE 802.11s protocol
The wireless Mesh network, known as the cheap "Last Mile" broadband access solution, utilizes a multi-hop wireless mesh structure to provide broadband access to mobile users. Mesh is a combination of WLAN and mobile Ad Hoc (peer-to-peer) networks. Compared with the WLAN, each network terminal can communicate directly with each other, and no longer needs to be forwarded by the AP (base station), and the coverage is larger. Compared with Ad Hoc, due to the fixed and power-filled backbone router, there is no need to consider too much in terms of mobility and power consumption.
Advantages: The network deployment is fast, no complicated configuration is required; the network is stable, any node is broken, and the data transmission of other devices is not affected; the network coverage is large, and various broadband wireless access technologies (such as WLAN, WiMAX, UWB, 3G, etc.) can be used. Combined to form a larger multi-hop network structure.
Disadvantages: It has a certain delay, is not suitable for real-time monitoring applications, and has limited network capacity.
4. Bluetooth / IEEE 802.15.1 protocol
Bluetooth technology first began in 1994 and was developed by Swedish Ericsson. It uses Frequency-hopping Spread Spectrum and the communication band is 2.402GHz-2.480GHz. Up to now, nine versions have been updated, namely Bluetooth 1.0/1.1/1.2/2.0/2.1/3.0/4.0/4.1/4.2, and the communication radius extends from a few meters to several hundred meters.
When WeChat and Baidu cloud are still not popular, we are always used to open the Bluetooth device in the mobile phone and share the fun and good things on the mobile phone to the friends around us. Bluetooth technology is widely used in mobile devices such as mobile phones, PDAs, PCs, GPS devices, and a large number of wireless peripheral devices (Bluetooth headsets, Bluetooth keyboards, etc.).
Bluetooth technology is also closely following the development of the Internet of Things. The latest Bluetooth 4.2 data transfer rate of up to 1Mbps, more powerful privacy features, Ipv6 network support. In the smart home field, Bluetooth devices using the Bulltooth Smart technology can achieve "conversation" between devices and devices without a network connection. This can solve the problem that the smart home devices will continue to work if the network is suddenly disconnected without WiFi.
Advantages: fast speed, low power consumption and high security.
Disadvantages: There are few network nodes, which are not suitable for multi-point control.
5.ZigBee/802.15.4 protocol
Zigbee was officially proposed in 2003. It appeared to compensate for the high complexity of Bluetooth communication protocols, large power consumption, close distance, and small network size. The name is taken from the bee, which relies on the “dance†of flying and “zig†to shake the wings to communicate with the companion. The way in which the pollen is located constitutes a communication network in the group.
ZigBee operates in three frequency bands 868MHz-868.6MHz, 902MHz-928MHz and 2.4GHz-2.4835GHz, the last of which is universal, 16 channels worldwide, and this band is a free, application-free radio band. The three bands have transmission rates of 20 kbps, 40 kbps, and 250 kbps, respectively.
ZigBee uses self-organizing network to communicate, and is also the most famous wireless communication protocol in the field of wireless sensor networks. In a wireless sensor network, when a message of a sensor cannot be smoothly transmitted from a certain communication path, the dynamic router can quickly find another channel transmission data at a close distance, thereby ensuring reliable transmission of information.
ZigBee is not a mainstream wireless communication technology, but it is highly sought after by some manufacturers for its low power consumption, low cost, low speed, high capacity and long battery life. For example, in 2015, Xiaomi launched a series of home smart products, all supporting ZigBee communication, and the recently launched millet temperature and humidity sensor.
Advantages: high security, low power consumption, strong networking capability, large capacity, and long battery life.
Disadvantages: high cost, poor anti-interference, ZigBee protocol is not open source, communication distance is short.
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