Fundamental properties of ad-hoc networks like Bluetooth: a radio network perspective

Ad-hoc systems can be characterized by the absence of infrastructure and centralized control. While the foregoing properties facilitate easy deployment, radio propagation conditions in ad-hoc networks are much more unpredictable than in planned and systematically laid-out cellular networks. Because of this difficulty to anticipate the channel conditions, approaches that have successfully been used to optimize the overall radio network performance of cellular systems cannot simply be applied to ad-hoc systems. Instead, these optimization approaches have to be evaluated carefully for their applicability in ad-hoc environments. This paper explains what should (additionally) be taken into account when designing forward error correction, power control, link adaptation, or carrier sensing schemes for ad-hoc networks. Motivated by the scientific and industry attention that Bluetooth is receiving, it is used here as an example technology. This paper shows that for Bluetooth neither link adaptation nor carrier sensing are appropriate means to improve the radio network performance, that an automatic repeat request algorithm need not be supported by forward error correction and that signal strength based power control performs best in case of full compensation of the path loss variation.