Noh-Gyoung Kang

Frequency-Dependent UWB Channel Characteristics in Office Environments

This paper reports frequency-dependent ultrawideband (UWB) channel characteristics. Measurements were performed in 103 receiver locations of six different office environments. From the measured data, the effect of frequency on the path-loss properties of a UWB signal is analyzed. After analyzing the path-loss behavior to propagation environments, the path-loss exponent variation models are developed in various environments as a function of frequency. Based on these models, path-loss prediction is performed, and the accuracy of the prediction is compared with those of existing path-loss models. In addition, the frequency-dependent UWB channel correlation characteristics are investigated. For the frequency correlation statistics of the UWB channel, double-slope models representing correlation coefficients are established with and without line-of-sight (LOS) paths. Using these correlation models, a channel gain estimation algorithm is proposed. The performance of the proposed estimation algorithm is evaluated with estimation parameters, and it is confirmed that the proposed estimation algorithm has better performance than the conventional algorithm using a linear interpolation algorithm.

Empirical Ultra Wide Band Path Loss Model in Office Environments

This paper reports the empirical path loss model of ultra wide band (UWB) communications in office environments. The channel transfer functions of 46 transmitter-receiver location pairs are acquired using channel measurement system based on frequency sweep method. From the measured data, parameters of log-distance path loss formula are extracted considering propagation environments and existence of a line of sight path. The effect of frequency to the path loss properties of ultra wideband signal is presented also. Finally, statistical properties of received signal power with respect to the receiver conditions are analyzed

Empirical Ultra Wide Band Channel Model for Short Range Outdoor Environments

This paper reports the empirical ultra wide band (UWB) channel model for short range outdoor environments. The measurements were performed based on the frequency sweep method in frequency domain at two different parking lot environments. From the measured channel transfer functions, parameters of log-distance path loss law and the effect of frequency to the path loss exponent are extracted. The distribution of received signal is analyzed to the existence of line-of-sight (LOS) path also. For the characterization of frequency dependent UWB channel parameters, standard deviation and correlation properties of channel gain in frequency domain are analyzed. The standard deviation increases with transmitter-receiver separation in LOS condition and the correlation is regressed to the double-slope model.

Effect of Metal Door on Indoor Radio Channel

This paper reports the variation of indoor radio channel caused by metal door. The simulation results using the finite difference time domain (FDTD) method and measurement results using the vector network analyzer in frequency domain are used for the characterization of received signal strength variation by metal door. Target frequency bands are three - sensor band, 802.11b ISM band, and 802.11a UNII band. From the simulation and measurement results, the effect of door angle to the received signal strength in three frequency bands and effect of radio frequency to variation are investigated. And FDTD simulation parameters for different environments are suggested.

Performance of Channel Prediction Using 3D Ray-tracing Scheme Compared to Conventional 2D Scheme

Channel prediction tools using ray-tracing scheme can be used to get information of communication channel instead of channel measurement. Three dimensional (3D) ray-tracing technique is known for the better accuracy compared to two dimensional (2D) ray-tracing. But it requires a lot of calculations, thus 2D simulation has been generally performed. This paper shows how precious 3D ray-tracing predicts the received power indoors compared to 2D one. For this work, wave propagation phenomena are analyzed using finite difference time domain (FDTD) method and the channel measurement data also will be offered as a standard of comparison

Characterization of spatial channel model based on ray path analysis in high-rise urban environment

The strongest ray analysis based on the computer simulation of wave propagation between a base station(BS) and mobile stations(MSs) is carried out to obtain the spatial-time wideband channel characteristics. The strongest rays are responsible for about 70% of the total received power for BS-MS pairs on the average and their arrival angles rarely deviate from the shortest path lines between a BS and MSs. However, this does not mean that the strongest ray is necessarily the first arrived ray for each BS-MS pair. The AOA statistics reveal that AOAs of the strongest and the second strongest rays are very close to each other for uplink channel, while those are quite apart for downlink channel.