Research On Bluetooth Protocol Based On Android Kernel Log

Bluetooth is a wireless technology standard for exchanging data over short distances from fixed and mobile devices.All devices that conform to the Bluetooth specification can easily establish a voice and data link without wire in short distance.Bluetooth technology has the characters of low power consumption, strong anti-interference, good compatibility and so on.The Bluetooth standard is also completely open around the world.Applications of Bluetooth technology are widely used, especially in the portable terminal product. In order to use Bluetooth technology to its full potential,we need further research on Bluetooth protocol.But the existing methods on it are mostly based on business softwares.These methods either cost too high or are not accurate because of the high packet loss rate,thus we cannot research the Bluetooth protocol completely and detailedly.We need a new way which is efficient and low cost to research the Bluetooth protocol.Bluetooth system structure, Android Bluetooth architecture and low-level code are deeply analyzed in this paper.On this basis, a new way is proposed to analyze the Bluetooth protocol. That is packet capture technology based on kernel log. First it analysises Android kernel source and locates the data transmission interface between Bluetooth protocol layer and hardware.Then print the Bluetooth communication packets to the Android kernel log by the interface, deriveding the kernel log file to the local by root permissions.Next researching the packet structure, link establishment and packet format of HCI, L2 CAP, SDP and RFCOMM based on the packets captured.Finally, experimental results prove that the packet capture method presented in this paper can capture the Bluetooth packets precisely with low cost in real-time. It meets the basic demands of researching Bluetooth protocol. Also the paper researches the Bluetooth protocol detailedly. On this basis, it proposed the solution to expand Bluetooth protocol,which sets up a firmly basis for the expansion of Bluetooth protocol and development in Bluetooth.