The theory of propagating waves near a surface is reviewed with an eye to gain insight into the mechanisms involved, and to provide analytical-based models, for power-efficient on-body propagation. The Zenneck wave, and in particular the Norton wave, are appraised as candidate mechanisms for the propagation. For flush-mounted ("band aid") antennas, desired for on-body sensors, the Norton wave is the only direct propagation mechanism between the sensors. The Norton wave fits very well to simulation results presented here, and comparisons are also made with available published physical experiments, although these measurements typically feature the optical paths of elevated, or non-flush, antennas.

Localized spectrum sensing is an alternate for database centric approaches to solve secondary use of spectrum in cognitive radios. This can be carried out by using collaborative spectrum sensing where larger amount of small devices is utilized for local spectrum sensing. This paper describes an mobile device scale implementation of multi-mode, multi-band spectrum sensor for cognitive radio. Cyclostationary feature detector algorithm is utilized to detect digital television (DVB-T/H) on UHF band and IEEE802.11a/g on 2.4/5 GHz (ISM/WLAN) bands. A miniaturized spectrum sensing device encounters physical challenges; like limited size and battery capacity, but provides opportunities to establish a dense network and fast response to dynamic chances in signal conditions.

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