Bluetooth Mesh Technology

 

Since July 2017, Bluetooth Special Interest Group (SIG) released the BT Mesh specification, under the promotion from Alibaba, Xiaomi, Tuya and other platform manufacturers, and effort of chip manufacturers, solution providers, franchisers, and developers, the BT Mesh market has grown rapidly, and both the number of products which supports Mesh and the user experience have been greatly improved. In addition, many wireless networking solution developed by solution providers based on Mesh technology are widely used in smart home, smart hotel, educational lighting, stage photography and other fields, which made a great success.

Realtek is one of the earliest chip manufacturers launched Mesh solutions, RTL8762 series can provide complete BT Mesh solutions. Its integrity is not only shown by take the role of both Mesh Device and Mesh Provisioner, but also supports both standard Mesh based on broadcast data communication and private Mesh based on GATT connection. These two Mesh technologies complement each other and have their own advantages.

The topological graph for standard Mesh network based on SIG is shown below:

RTL8762x provides all solutions in the frame diagram above:

1.Phone Mesh Apk connect into Mesh network by Proxy

2.Ultra-low power single live switching solution based on low duty cycle scanning

3.Low power gate magnetic solution based on Friend/LPN Feature

4.Bluetooth transfer to infrared devices, also connects traditional infrared devices into the Mesh network

5.Support both standard Mesh and dual mode electric curtain solution controlled by traditional remote control

6.Rapid OTA

Standard SIG Mesh is the network mode based on a flood broadcast, which determines that it has a very little effective bandwidth. Each packet carries a maximum of 11 bytes of valid data, and the valid data transfer rate is less than 1kB per second. Thus, SIG Mesh is not suitable to be applied in scenarios with large data volumes. In addition, ADV-SCAN has low communication efficiency and high power consumption.

Private Mesh network based on GATT Connection

RTL8762x supports master/slave integration, supports maximum of  "3 masters and 8 slaves", which means RTL8762x can be connected by 3 masters and connect 8 slaves at the same time. With this Feature, a private Mesh network based on GATT connection can be built and realize the AD Hoc networking function of the device.

The number of slaves connected with each master will affect the time and bandwidth allocated by the slave, network topology level, connection stability, and system delay, etc. The selection should be made comprehensively based on the requirements of various indicators. Usually it is recommend that 1 master connect 3 to 4 slaves.

The advantage of SIG Mesh is that it is based on an uniform standard, high interoperability, high security, has mature protocol and easy to implement, which is mainly used on simple network system with small amount of data, such as lighting control system.

Private Mesh network satisfied the need of low power cost and a big amount of data for communication, but the communication protocol needs to be customized, which is difficult to implement. Therefore, it is suitable for building a closed communication system.

Comparison of two Mesh technologies:

	SIG Mesh	Private Mesh
Communication mode	Flood broadcast, no route	GATT connection，has route
Effective bandwidth	<1KBps	Maximum dozens of KBps
Transmission reliability	Unreliable transport, protocol layer sets times	Reliable transport, automatic re-transmission if necessary
Channel	3 broadcast channels	37 data channels
One hop latency	Approximate 15ms	Average 15ms
Network size	hundreds	hundreds
Low power @ 1s communication once	100uA	20uA
Difficulty of system	Simple, has mature protocol	Complex，needs customized protocol