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UHF TV channels are traditionally used for television broadcasting where the channels can be regarded static or slowly-varying. Due to the transition from the analog television to the digital television, the UHF TV channels 52-69 will be reallocated to other applications and there is a need of re-evaluation of these channels under the new operational environments, e.g. mobile downlink and uplink channels with antenna arrays at the transmitter and the receiver. In this paper, new results on the temporal and spatial characteristics of the wideband UHF mobile wireless signals and channels in the Digital Television (DTV) broadcasting UHF frequency bands are presented. Our analysis of DTV mobile field measurements confirms that the complex channel correlation amplitude depends on the channel phase correlation and differs considerably from the channel envelope correlation. Furthermore, the autocorrelation of the ATSC DTV transmitted signal, embedded in our received signals, degrades the received signal amplitude correlation coefficients, in comparison with the channel envelope correlation coefficients, and increases the complex received signal correlation coefficients, in comparison with the complex channel correlation coefficients, in highly correlated channels. Both downlink and uplink DTV mobile broadcast channels are investigated. The field measurement results also show that the channel envelopes are highly correlated while the channel phases are uncorrelated. This may lead to the advent of a space time code or a modulation scheme that utilizes the phase information in order to maximize the channel capacity. The results exposed in this paper are important for designers of new mobile wireless systems in order to build new wireless applications, modulation schemes, equalizers and channel-tracking algorithms in the UHF TV spectrum.
Date of Publication: June 2010