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Subject: search.filters.subject.Low base station

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    Muti-layer fuzzy logic sets for mobile path loss in forests
    (2007-08-08)
    Phaiboon, Supachai
    ;
    Phokharatkul, Pisit
    ;
    Somkuarnpanit, Suripon
    Mobile path loss prediction in forests using Multi-Layer fuzzy logic system (MLFS) is presented in this paper. The MLFS consists of a tree density decision layer which is a supervisory layer in order to select the next layers using fuzzy decision. The sub-predictions use a set of rule base that provide path loss prediction in each case of an environment. These crisp inputs are classified by the fuzzifier to fuzzy sets and then inferenced using fuzzy linguistic rule base into multi - output path loss slopes via de-fuzzifier. For this study, we classified the terrains into high-, medium-, low- density and grass area and used the simple linguistic rules for prediction of the path loss slopes. We performed measurements in different forest densities at a frequency of 1.8 GHz with base station antenna height in a range of 3, 4, and 5 m above ground while the receiving antenna height was fixed at 1.8 m above ground. The results have shown that fuzzy logic approach provides more accurate prediction of path loss slopes than that of conventional empirical mathematic models. The proposed models will be useful for the local wireless network and micro-cell design of mobile communication systems in forests. ©2006 IEEE.
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    Fading analysis of vegetation density effects on path loss for 1.8 GHZ cellular mobile with low base station antenna height
    (2006-12-01)
    Phaiboon, Supachai
    ;
    Pitithammawong, Kitti
    ;
    Chulajata, Tatcha
    ;
    Somkuarnpanit, Suripon
    This paper presents studies of propagation characteristics in a suburban forest based on a measurement campaign at a frequency of 1.8 GHz. We investigated how tree density affected the fast fading characteristic depending on tree density and base station antenna height in a range of 3, 4, and 5 m above ground while the receiving antenna height was fixed at 1.8 m above ground. Three categories were studied: high density area, low density areas and grass area. Measurement of the receiver signal over 120 s intervals for a stationary mobile were used to obtain the distribution functions for the fading. We found that the distributions followed a Rician distribution, whose K-factor depended on tree density and transmitter height.
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    Mobile path loss characteristics for low base station antenna height in different forest densities
    (2006-11-02)
    Phaiboon, S.
    ;
    Somkuarnpanit, S.
    This paper presents studies of propagation in a suburban forest based on a measurement campaign at a frequency of 1.8 GHz. We investigated how tree density affected path loss-distance and the fast fading characteristic depends on base tree size and base station antenna height in a range of 3, 4, and 5 m above ground while the receiving antenna height was fixed at 1.8 m above ground. The path loss exponent is found that to average 3.8, 3.7 and 2.2 for the measurement areas of high, medium, and low densities respectively. The high density area with low tree heights provides maximum path loss exponents. Path loss in the same density area depends on the number of trees in the direct path between the transmitter and the receiver. The measurement of signal variation shows that a multi-path contribution becomes more significant as the base station antenna is raised. © 2006 IEEE.
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    Mobile path loss prediction model for forest areas using MIMO fuzzy logic system
    (2006-09-01)
    Phaiboon, Supachai
    ;
    Phokharatkul, Pisit
    ;
    Kittitummawong, Piti
    ;
    Somkuarnpanit, Suripon
    This paper proposes a method to predic mobile path loss in forests using MIMO fuzzy logic system. The multi-input was classified into seven input parameters defined as, X1 is number of trees/m<sup>2</sup> and X2 to X7 are tree structure parameters. These crisp inputs are classified by fuzzifier to fuzzy sets and then inferenced using fuzzy linguistic rule base into multi - output path loss slopes via de-fuzzifier. For this study, we classified the terrains into high-, medium-, low- density and grass area and used the simple linguistic rules for prediction the path loss slopes. We performed measurements in different forest densities at a frequency of 1.8 GHz with base station antenna height in a range of 3, 4, and 5 m above ground while the receiving antenna height was fixed at 1.8 m above ground. The results have shown that fuzzy logic approach provides more accurate prediction of path loss slopes than that of conventional empirical mathematic model. The proposed models will be useful for the local wireless network and micro-cell design of mobile communication systems in forests.