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Author: search.filters.author.Chamchoy, MonchaiSubject: search.filters.subject.Ultra wideband (UWB)

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    A body-shadowing model for indoor UWB communication environments
    (2008-10-06)
    Seesai, Waraporn
    ;
    Chamchoy, Monchai
    ;
    Promwong, Sathaporn
    Radio channel characteristic is a very important factor for designing indoor UWB communication network. As we know, the indoor communication channel is limited by geometry of room and some obstruction in that room such as furniture, human operator, etc. These obstructions directly affect to quality of received signal, especially human who usually obstruct receiving signal. To efficient the network designing, the influence of human body shadowing on radio propagation in building UWB communication is investigated by involving propagation prediction model. This model will predict characteristics of the received signal affected from body shadowing by considering many wave propagation phenomenons such as reflection, refraction, absorption, etc. based on ray-tracing technique. The predicted results are shown in various forms such as power loss of received signal, mean excess delay and power delay profile. To verify the validation of the model, these results will be compared with the measured results. It is found that the measurement and prediction results are closely related. ©2008 IEEE.
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    Characteristics of UWB propagation through building materials
    (2005-12-01)
    Jaturatussanai, Pongsatorn
    ;
    Chamchoy, Monchai
    ;
    Promwong, Sathaporn
    UWB system is the one type of several wireless communication that can be used in home networking, which have any probably obstruct by building material. Then the influences of the obstructions are considered. In this paper, the time dispersion and penetration loss are studied. The glass, gypsum, dry wood and partition board are considered the obstruction materials. The channels with these materials are measured in a fully anechoic chamber by using the vector network analyzer. The measurement frequency range is set to be 3-11 GHz, which covered the full band of UWB specified by FCC. The biconical antennas are used for both transmitter and receiver. The time dispersion and penetration loss for each material are evaluated based on the measurement channels. The data of theses results is useful for considering the UWB link budget.
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    A study on performance of UWB system in the presence of IEEE 802.11a interference
    (2005-12-01)
    Pakdeechard, Eakaraj
    ;
    Chamchoy, Monchai
    ;
    Promwong, Sathaporn
    This paper illustrate the effects of IEEE 802.11a narrowband interference (NBI) on ultra-wideband (UWB) system. The empirical path loss model is considered for UWB time-hopping transmission with both pulse position modulation (PPM) and bi-phase modulation (BPM). Our study demonstrates that significant performance loss increases as the T-R separation increases. Moreover, the performance of UWB-PPM in the presence of NBI also better than BPM. Therefore, the BER performance is sensitive to the separation distance between the transmitter and the receiver. Moreover, it also depends on the separation between the UWB receiver and the IEEE 802.11a interferer. © 2005 IEEE.
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    Investigation of ultra-wideband pulse distortion due to the body shadowing
    (2005-12-01)
    Pradabphon, Apichit
    ;
    Doungdeun, Worawoot
    ;
    Chamchoy, Monchai
    ;
    Supanakoon, Pichaya
    ;
    Promwong, Sathaporn
    In this paper, the distortion of ultra-wideband (UWB) pulse due to the human body shadowing is investigated. The frequency responses of the radio channels are acquired by using a vector network analyzer (VNA) over the frequency bandwidth of 3 GHz to 11 GHz. The experimental channels are taken for several T-R separation distances in the indoor environment. Consequently, the characteristics of the UWB pulse distortion including the effect of transmitter/receiver antennas and human body are examined. The pulse distortion is considered by using the percentage of the correlation coefficient between the transmitted signal and the received signal. As the results, the distortion of UWB pulse increases as the T-R separation distance increases, especially when the fully shadowing is observed. © 2005 IEEE.