Wireless Communications: Principles and Practice
Wireless Communications: Principles and Practice
Design considerations for solar energy harvesting wireless embedded systems
IPSN '05 Proceedings of the 4th international symposium on Information processing in sensor networks
Prediction of outdoor and outdoor-to-indoor coverage in urban areas at 1.8 GHz
IEEE Journal on Selected Areas in Communications
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This paper presents and compares measured propagation data taken at four unlicensed-band frequencies including 151MHz, 433MHz, 902MHz and 2400MHz. A custom 10mW signal source was used as the transmitter, and a spectrum analyzer as the receiver to provide accuracy to within 1dB and sensitivity to better than -120 dBm. Both monopole and low-gain directional antennas were employed to represent expected use in an Energy Harvesting application. The measurement environment included both indoor and outdoor features. A range of up to 1.5km at the lower frequencies was achieved. The path-loss exponent was found to be approximately three to five and relatively independent of the operating band. Results confirm that lower frequencies are preferred for low-power applications when omni-directional and low gain antennas are used.