TITLE:
Optimization of Leaky Feeder Slot Spacing for Better Beam Forming in Mines and Tunnels
AUTHORS:
Noha Hassan, Wisam F. Farjow, Xavier Fernando
KEYWORDS:
Beam-Forming Antenna, Leaky Feeder, Millimeter-Wave Frequencies, Optimization
JOURNAL NAME:
International Journal of Communications, Network and System Sciences,
Vol.9 No.4,
April
27,
2016
ABSTRACT: The radiating cable (or leaky feeder) is the leading solution for
distributed broadband wireless access in underground mines and tunnels. The
traditional radiating cable has equally spaced slots along its axis radiating
evenly. However, with the new requirement for tracking and localization of
miners, this paper shows how to modify the leaky feeder to function as a beam
forming antenna array by appropriately optimizing the slot spacing. Optimizing
the leaky feeder slot distances using Genetic algorithm has a good impact on
the channel parameters, making it an excellent choice for leaky feeder
antennas. Linear, as well as bent practical leaky feeder shapes, were
considered, and we tested five different optimization algorithms and compared
side lobe energies, varying the slot distance which had an impact on side lobe
level. Also, we derived the expression for the BER, spectral efficiency and
throughput considering a time-varying wireless channel. We observed that as the
radius of curvature of the feeder increased (approaching a straight line), the
spectral efficiency decreased as expected. Interestingly different optimization
algorithms perform differently at different carrier frequencies. An
optimization method should be chosen according to the required goal to be
achieved (maintaining uniform equal power along the cable, or a more directed
beam, or using a certain frequency of operation).