Title :
Characterization of Low-Antenna Ultrawideband Propagation in a Forest Environment
Author :
Anderson, Christopher R. ; Volos, Haris I. ; Buehrer, R. Michael
Author_Institution :
Wireless Meas. Group, United States Naval Acad., Annapolis, MD, USA
Abstract :
Impulse ultrawideband (UWB) communication promises a number of benefits for use in wireless sensor networks, particularly in forest environments, where it has the potential to provide robust operation, along with the ability to combine communications with precision position location. In this paper, we present measurement results and empirical models for UWB signal propagation in a forest environment. Path-loss measurements were performed using a 620-ps duration UWB pulse with a frequency range of 830-4200 MHz. More than 22 000 measurements were recorded in 165 locations in four diverse forest environments in Virginia and Maryland, USA. Transmitters and receivers were separated by distances that range from 4 m to 50 m. Large-scale path loss was most closely modeled by log-distance propagation, with path-loss exponents ranging from 2.5 to 3.8. Small-scale fading analysis indicated that UWB signals experience Rician fading, with K-factors in the range of 10-16 dB. K-factors were found to depend on forest type, with the medium-density forest providing the greatest number of multipath components and highest overall K-factor. Multipath component analysis demonstrated that a forest is a fairly rich multipath environment; however, in most cases, approximately 90% of the available energy was contained within the strongest 3-15 multipath components. Postprocessing analysis divided the UWB pulse into three frequency subbands and demonstrated that model parameters also had frequency dependence. These measurements and models should aid in the development of future UWB outdoor sensor networks.
Keywords :
Rician channels; UHF antennas; UHF radio propagation; loss measurement; microwave antennas; microwave propagation; multipath channels; radio receivers; radio transmitters; radiotelemetry; ultra wideband antennas; ultra wideband communication; wireless sensor networks; K-factor; UWB outdoor sensor network; UWB pulse; UWB signal propagation; distance 4 m to 50 m; diverse forest environment; frequency 830 MHz to 4200 MHz; frequency subband; gain 10 dB to 16 dB; impulse ultrawideband communication; large-scale path loss measurement; log-distance propagation; low-antenna ultrawideband propagation; medium-density forest type; multipath component analysis; postprocessing analysis; precision position location; receiver; small-scale Rician fading analysis; time 620 ps; transmitter; wireless sensor network; Antenna measurements; Brushes; Frequency measurement; Loss measurement; Receivers; Transmitters; Vegetation; Forest; Rician fading; multipath channels; ultrawideband (UWB); wireless propagation;
Journal_Title :
Vehicular Technology, IEEE Transactions on
DOI :
10.1109/TVT.2013.2251027