In addition to classic Bluetooth and Bluetooth low energy, Bluetooth Mesh should be the most popular Bluetooth vocabulary in recent years. Bluetooth Mesh technology is an application technology based on the BLE protocol developed to meet the development requirements of the Internet of Things and draw on other wireless communication technologies (such as Zigbee). That is to say, the essence of Bluetooth Mesh is still BLE, but it is only one form of application.
The birth of Bluetooth Mesh technology
The birth of Bluetooth Mesh technology is similar to low energy Bluetooth, and it is also “All-takenism”. Before Bluetooth Mesh, there were only two forms of connection between Bluetooth devices: point-to-point mode (classic Bluetooth BT) and point-to-multipoint (Bluetooth Low Energy BLE). These two connection methods are not suitable for fields such as smart home and industrial Internet of Things. Compared to Bluetooth’s old rival, Zigbee technology has a lot of advantages in this regard. Zigbee naturally supports mesh networking and can realize multi-point-to-multi-point connections. However, due to its low transmission rate and the need for additional network management to connect to the Internet, Zigbee technology has not shown its due advantages in the field of smart homes and obtained corresponding market position. The lack of Mesh networking capability has always been a shortcoming of Bluetooth technology. The history of the Bluetooth Mesh protocol starts with CSR. CSR was founded in Cambridge, England in 1998. It mainly develops GPS and Bluetooth chips. The company’s full English name is “Cambridge Silicon Radio”. In 2014, the CSR R&D team developed CSR Mesh technology based on Bluetooth technology. It uses star network and relay technology. Each network can connect more than 65,000 nodes. The device is interconnected or directly controlled by the same mobile phone, tablet or PC, which is the first in the industry, and claims to want to kill Zigbee. But at that time this technology was still a private agreement, but CSR said at that time that it would donate this technology to SIG. In 2015, Qualcomm spent 2.4 billion US dollars to acquire CSR company, of which Qualcomm’s most important asset of CSR company is CSR’s core technology – CSRMesh. Qualcomm also supported the donation of CSR Mesh to the SIG, and fully contributed the CSR Mesh source code. After that, the Bluetooth Alliance quickly launched the Bluetooth Mesh standard. On July 19, 2017, the Bluetooth SIG officially announced that Bluetooth technology began to fully support Mesh network. The new Mesh function provides many-to-many device transmission, and especially improves the communication efficiency of building a large-scale network coverage. It is suitable for building automation, wireless sensor networks and other objects that require tens of thousands of devices to transmit in a reliable and safe environment. networking solutions.
Features of Bluetooth Mesh
Bluetooth Mesh is based on the core standard (core spec) 4.0. From the beginning of the design, it strictly follows the requirements of industrial-grade reliability, scalability and security. It brings together low power consumption, support for mobile phone/tablet direct connection, interoperability, etc. Bluetooth Mesh can support up to tens of thousands of nodes in a single network. It uses a controllable flooding (network flooding) method to forward information, and forwards information from a node in the network to the destination node without creating and Manage complex routing tables. Due to its broadcast characteristics, if any single point in the network fails, messages can be delivered to destination nodes through other paths, ensuring the robustness of the network.
Low Power Feature
Low power consumption is a major advantage of Bluetooth technology, and this advantage is also inherited in Bluetooth Mesh technology. In the Bluetooth Mesh network, there is a type of node that supports the Low Power Feature , which can also be called a low-power node. This type of node can achieve the purpose of low power consumption by reducing the duty cycle of the RF transceiver (RF transceiver) turned on, that is to say, this type of node will only turn on the RF transceiver when it needs to send and receive messages. time dormant.
There is also a type of node in the Bluetooth Mesh network that is dedicated to serving low-power nodes. It has the Friend feature and can also be called Friend node. Friend nodes and low-power nodes can establish a friendship relationship. After the relationship is established, the Friend node can temporarily store the information sent to the low-power node, and retrieve the relevant information from the Friend node after the low-power node exits the sleep mode. In practical applications, Friend nodes can be light bulbs, set-top boxes, and routers. These devices are powered by mains and are not very sensitive to power consumption; low-power nodes can be battery-powered devices, such as sensors, door locks, etc. .
Bluetooth Mesh Networking is a true industrial-grade solution that uses proven security algorithms to provision devices added to the network; all communications need to be encrypted and authenticated using 128-bit AES-CCM, Bluetooth Mesh All messages in the network need to be encrypted and authenticated; encryption and authentication are applied to the network layer and the application layer, with two sets of keys, etc.