Modelling and performance analysis of an adaptive state-transition approach for power saving in Bluetooth

In this paper, an approach is developed to improve the power efficiency of Bluetooth. The better efficiency is achieved by reducing the unnecessary polling operations in the Basic Rate/Enhanced Data Rate (BR/EDR) controllers. An analysis of the current low power modes in the Bluetooth BR/EDR controller indicates that their activation requires a critical and challenging parameter negotiation phase. These parameters have a wide range of choices and as a result the associated low power modes are typically ignored by the Bluetooth application developers. The new approach is based upon multiple polling intervals. It is shown that three different polling intervals: small, medium and large are sufficient for a broad range of data traffic scenarios. As the kernel idea, each controller runs a common algorithm to choose among the three polling intervals and adaptively switches link state between the active data transfer state and idle. The state-transition rules are derived, and a system model is established based on the Hidden Markov Model (HMM), which is used to analyze and design the new Bluetooth link state-transition algorithm. The simulation and analysis demonstrates significant power saving and relatively low average end-to-end packet delay for this state-transition based approach, in comparison to the conventional polling system and the low power sniff mode. Moreover, the state-transition approach enables easier parameter setting that can be further optimized for a specific Bluetooth scenario.