Research Of Bluetooth Multi-piconet System And Emulated Serial Ports

"The scope of wired application is limited, whereas the scope of wireless application is unlimited". Wireless is one of the development trends of communication. Various short-range wireless communication technologies occur in order to realize people's dream of accessing information anytime and anywhere, among which Bluetooth is generally regarded as the preferential technology for WPAN.The basic unit of Bluetooth network is piconet, which is like a micro-cell that can provide up to 7 user's active access within 10 meters. In order to provide adequate access bandwidth, multiple piconets shall be located within one area,which form a multi-piconet system. Interference exists between piconets. Data transmission will fail if two piconets select the same RF channel to transmit packet in the same time. By using interference model, theoretical analysis and simulation show, with the increase of piconets in the system, the impact of self-interference to the system throughput increases rapidly.Bluetooth Specification v1.2 introduces Adaptive Frequency Hopping (AFH) tech- nology to reduce the interference between Bluetooth and 802.11b by separating the shared spectrum. Research shows, AFH can also be used to reduce the self-interference between piconets. It can significantly increase the throughput of the system which has more piconets.Different tactics should be adopted according to the requirements in the design of a multi-piconet system, such as inquiry mode, handover between piconets, etc. Quite a few applications use emulated serial port based on RFCOMM, whose multiplex property can provide a shared emulated serial port. Research shows that using the shared emulated serial port can save the server channels and increase the connection success rate.