Browsing by Author "Suripon Somkuarnpanit"

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    Analysis and measurement of radio-frequency interference due to the corona from 500 kV transmission lines
    (2000-12-01) Supachai Phaiboon; Vech Vivek; Suripon Somkuarnpanit; Mahidol University
    This paper presents a method to consider the radio-frequency interference (RI) induced by corona from the EHV transmission line system. There are two major types of RI in our consideration. The first is the RI radiated from the transmission line at typical conditions. The other is the relative RI due to the change of environmental factors such as air density, ground conductivity and the determined frequency. The overall RI is described by the sum of these two RI's. The modeling RI for n-phase transmission lines is described, especially, for the three-phase 500 kV system. The experimental data of RF signals were obtained by a survey of 24 sites along the 500 kV power lines along the 800 km distance. The RF signals from the power lines in both vertical lines and horizontal line systems were investigated in terms of the spectral levels of frequencies from 0.5 to 100 MHz at the distance away from the power lines. The results are relatively well matched to our theoretical model, and hence, may use the model to prevent this RF interference.
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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) Supachai Phaiboon; Kitti Pitithammawong; Tatcha Chulajata; Suripon Somkuarnpanit; Mahidol University; King Mongkut's Institute of Technology Ladkrabang
    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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    Microwave line-of-sight path loss prediction on urban street by fuzzy logic model
    (2005-12-01) Supachai Phaiboon; Pisit Phokharatkul; Suripon Somkuarnpanit; Sitchai Boonpiyathud; Mahidol University; King Mongkut's Institute of Technology Ladkrabang; Thammasat University
    This paper proposes a method to model the path loss characteristics on urban streets in the microwave band. We applied the concept of fuzzy logic to predict path losses. The input fuzzy sets were classified into five sets, namely 1) Distance between transmitter and receiver, 2) Frequency, 3) Time of day, 4) Transmitting antenna height and 5) Receiving antenna height. These inputs are then inferenced into output path loss via linguistic rules which were trained by measurement. To check the proposed model, we compared the fuzzy prediction with the same and an another measurement. The results show that the fuzzy logic models provided a better prediction. © 2005 IEEE.
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    Mobile path loss prediction model for forest areas using MIMO fuzzy logic system
    (2006-09-01) Supachai Phaiboon; Pisit Phokharatkul; Piti Kittitummawong; Suripon Somkuarnpanit; Mahidol University; King Mongkut's Institute of Technology Ladkrabang
    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/m2 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.
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    Modeling and analysis the effect of radio-frequency fields in hospitals to the medical equipment
    (2000-12-01) Supachai Phaiboon; Suripon Somkuarnpanit; Mahidol University
    This paper proposes a modeling and method to assess the RF interference in hospital areas. Field-strength measurement has done inside and outside of two main hospitals in Bangkok at frequency between 55 and 1918 MHz, and the data were compared to fields predicted using the proposed models. The measured fields generally remained below 1 V/m. The outside mode prediction method provided a worst-case estimation of the electromagnetic environmental hazard. The modeling method predicted fields to within a range of 12 dB.
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    Muti-layer fuzzy logic sets for mobile path loss in forests
    (2007-08-08) Supachai Phaiboon; Pisit Phokharatkul; Suripon Somkuarnpanit; Mahidol University; King Mongkut's Institute of Technology Ladkrabang
    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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    New upper and lower bounds line of sight path loss model for mobile propagation in buildings
    (2008-03-03) Supachai Phaiboon; Pisit Phokharatkul; Suripon Somkuarnpanit; King Mongkut's Institute of Technology Ladkrabang; Mahidol University
    This paper proposes a method to predict line-of-sight (LOS) path loss in buildings. We performed measurements in two different types of buildings at a frequency of 1.8 GHz and propose a new path loss model with its upper and lower bounds. The upper and lower bounds depend on max and min values of sampled path loss data. This makes our model limit path loss within the boundary lines. The model includes time-variant effects from the object movement from people in the building and cars in parking areas. These influence reasonably on wave propagation. The results have shown that the proposed model will be useful for the design of the indoor wireless communication systems. © 2007 Elsevier GmbH. All rights reserved.
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    An optical fiber feeder system and performance for cellualar microcell 800MHz CDMA systems
    (2001-12-01) Supachai Phaiboon; Suripon Somkuarnpanit; Mahidol University; King Mongkut's Institute of Technology Ladkrabang
    This paper proposes an optical fiber feeder system for use in cellular microcell 800MHz CDMA systems, as well as its performance. The RF signal of the CDMA system is converted into the optical signal, which can be delivered in the optical fiber. We analyze the system performance in terms of CNR (carrier to noise ratio) and SER (symbol error rate) using theoretical modeling as well as numerically calculation of the CDMA system compared with the intensity modulation. It is found that the optical feeder system for the CDMA system has got higher CNR than that of the system with intensity modulation, especially at low power level e.g. CNR more than 80dB for received optical power of -40dBm. This would provide a consequence of relatively low error rate in signal detection.
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    Upper-and lower-bound path-loss modeling for indoor line-of-sight environments
    (2005-12-01) Supachai Phaiboon; Pisit Phokharatkul; Suripon Somkuarnpanit; Sitchai Boonpiyathud; Mahidol University; King Mongkut's Institute of Technology Ladkrabang; Thammasat University
    This paper proposes a method to predict line-of-sight (LOS) path loss in buildings. We performed measurements in two different type of buildings at a frequency of 1.8 GHz and propose upper-and-lower bounds path loss models which depend on max and min values of sample path loss data. This makes our models limit path loss within the boundary lines. The models include time-variant effects such as people moving and cars in parking areas with their influence on wave propagation that is very high. The results have shown that the proposed models will be useful for the system and cell design of indoor wireless communication systems. © 2005 IEEE.