What is BLE mesh The official version of BLE mesh was released in July 2017, V1 .0, and is currently(as of May 2018). BLE is a low-power Bluetooth. It was proposed in Bluetown store spec 4.0. It was originally a classic Bluetooth. The initial version was released in 2000 and is generally called BR/EDR(Basic Rate and Improved Data Rate) classic Bluetooth. The power consumption of classic Bluetooth is relatively high. After several versions of 1.0 to 3.0, the data transmission rate has been greatly improved. The current application fields mainly include Bluetooth speakers, Bluetooth headphones, and early Bluetooth mice. Keyboard and so on. BR/EDR is a typical "point-to-point" communication method and is mainly used to replace close-range wired data transmission applications. In 2010, SIG released the low-power Bluetooth BLE, BLE and BR/EDR classic Bluetooth. The difference between the two is quite large, so the two are incompatible in communication, so when BLE comes out, it also gave birth to Bluetooth's "dual mode". It is a Bluetooth device that supports BR/EDR and BLE at the same time, which is dual-mode Bluetooth. The data rate of BLE has no advantage for classic Bluetooth. The speed of classic Bluetooth is faster, but the power consumption of BLE is extremely low, and BLE is proposed. It should also be seen that some embedded devices, computer peripherals and other low-power requirements at the time, so BLE is currently mainly used for some battery-powered embedded devices, common Bluetooth remote control, heart rate monitoring, Bluetooth watches, handrings and so on. Application scenes such as portable mobile phones, tablets, health, smart home, and wear. BLE actually supports the star network topology, that is, Central is a device that can connect multiple Peripheral characters. Of course, the number of Peripheral that the actual Central can connect is very limited. First of all, Central's memory, with each additional link, The memory consumed by its protocol stack will increase a lot. More importantly, RF's link maintenance, BLE is based on the connection interest, Master(Central) and Slave are constantly synchronizing to maintain the link, and the star topology, as the number of connections increases, In fact, the interval assigned to each Peripheral is very small, and Master has to handle the maintenance of all Peripheral links without conflict and without falling off. Of course, BLE's broadcasting can also support one-to-many communications. This technology should be the basis of BLE mesh. BLE mesh should be based on the limitations of the network topology of BLE above, and can support "multi-to-many". Therefore, BLE mesh is a network-supported feature designed for large-scale nodes to communicate with each other. Its application target scenario is such as building automation, sensor networks, and more IoT applications. Therefore, BLE mesh is not a new protocol stack technology. It is based on BLE technology and only regulates the upper layer of network layer applications so that it supports multiple to multiple application scenarios.