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Abstract-Dual site spectrum measurements have been made in the public safety band in Howard County, Maryland, USA. The public safety band is of interest because of its obvious importance and the increasing need to determine whether improved spectral utilization would accommodate increased usage for public safety. Two receiver suites were synchronized and used to measure concurrent spectra at separations between a few meters up to a few kilometers. These measurements prove useful in examining issues of spectrum sensing for dynamic spectrum access, including receiver sensitivity, primary user signal detection, adjacent channel interference, and policy performance with local and cooperative sensing. We analyze the collected data to characterize the usage of this public safety network and provide insights into how white space can be identified and utilized. We propose a class of opportunistic access strategies and demonstrate how collected data can be used to evaluate the performance of such schemes.Index Terms-dynamic spectrum access, public safety band, spectrum measurement, spectrum policy, and spectrum data analysis

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A series of experiments were conducted to characterize the propagation characteristics in an urban canyon setting between ground-based communicators operating within the military ultrahigh frequency band (225 to 450 MHz). The experiments were conducted over a two-day period in downtown Philadelphia. Profiles of received power versus distance were generated along a variety of straight and Lshaped paths for different radio frequencies and antenna heights. The results were analyzed to determine the dependency of the received power on street width, RF frequency, antenna height, and corner distance (the distance between the transmitter and the corner on an Lshaped path). The results showed well-defined dependencies on all of the parameters except antenna height, which did not appear to affect the results over the range of values considered in this study. The results are compared with similar measurements by other investigators operating at higher frequencies in an attempt to identify the impact of RF frequency on urban propagation. This study addresses an important but largely overlooked propagation environment.

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