Bluetooth adaptive frequency hopping and scheduling

In this paper, we investigate the use of adaptive frequency hopping (AFH) techniques aimed at modifying the Bluetooth frequency hopping sequence in the presence of WLAN direct sequence spread spectrum devices. We examine the conditions such as the applications, topologies, and scenarios under which AFH techniques improve performance that is measured in terms of packet loss, TCP delay, and channel efficiency. We also compare the results obtained with AFH to others obtained using a scheduling technique that consist in delaying the transmission of a Bluetooth packet until the medium is "idle". Our results show that an obvious performance improvement with AFH is in terms of delay and throughput. AFH brings the delay down to the same level than when no interference is present. On the other hand, AFH is rather slow in responding to changes in the environment and the packet loss is more significant than with the scheduling. This is probably due to the limitations imposed by the communication overhead. The main difficulty for AFH is having to dynamically communicate the changes to all slaves in the piconet in order to keep the synchronization.