Bluetooth Time Division Duplex-Exact Analysis as a Polling System

Bluetooth enables wireless communication via ad-hoc networks. The basic network topology (piconet) is a collection of slaves controlled by a master. A scatternet is a multihop network of piconets. Efficient piconet and scatternet communication requires design of intra and inter-piconet scheduling algorithms. Thus, numerous scheduling algorithms have been recently proposed. Analytical performance evaluation of such algorithms has great importance, since it may provide insight on their design and optimization. However, due to inherent complexities of the Bluetooth Medium Access Control (MAC), the performance of these scheduling algorithms has been analyzed mostly via simulation. Recently, Misic and Misic [17], [18], [19], [21], [22], [23], [24], [25] have claimed to provide exact analytic results regarding intra and inter-piconet scheduling algorithms which are based on the theory of M/G/1 queue with vacations. In this paper, we present alternative analytic results which are based on the theory of polling systems. Using these results we show that the results presented in [19] are incorrect, as they are based on unsatisfied assumptions leading to inaccurate probability generating functions. Thus, in some cases [19] underestimates the intra-piconet delay by more than 50% and in other cases it overestimates the delay by more than 50%. We also indicate that for similar reasons the results presented in [17], [18], [20], [21], [22], [23], [24], and [25] seem to be incorrect.