• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1165-1171
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• 2011

In this paper, we investigate hidden node problem to effectively utilize TV band devices(TVBDs) in the TV white space(TVWS), and also to protect digital television(DTV) service in Korea. Firstly, we classify the radio propagation environment into an urban area, a basin area, and a coastal area based on geographical characteristics. Thereafter, we measure and analyze local shape based hidden node attenuation at eight segmented positions in each geographic area. Because commercial buildings as well as residential and commercial buildings in Korea are located in closer proximity to each other than in other countries, hidden node margin should be more than 38 dB in order to safely protect DTV service in Korea.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.193-200
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• 2019

The auto-encoder network which is a good candidate to handle the modeling of the signal strength attenuation is designed for denoising and compensating the distortion of the received data. It provides a non-linear mapping function by iteratively learning the encoder and the decoder. The encoder is the non-linear mapping function, and the decoder demands accurate data reconstruction from the representation generated by the encoder. In addition, the adaptive network width which supports the automatic generation of new hidden nodes and pruning of inconsequential nodes is also implemented in the proposed algorithm for increasing the efficiency of the algorithm. Simulation results show that the proposed method can improve the neural network training surface to achieve the highest possible accuracy of the signal modeling compared with the conventional modeling method.