Myoung-Won Jung

Empirical Prediction Models of 1-min Rain Rate Distribution for Various Integration Time

In a wireless channel above microwave frequency, rain attenuation is very important. In order to predict rain attenuation, 1- min. rain rate distribution is required. This paper discusses appropriate conversion methods to estimate 1-minute rain rate from that of other integration time. Based on the measurement data filed in ITU-R WP3J including ETRI data for 6 consecutive years, distributions of rain rate with 1-, 5-, 10-, 20-, 30-minute integration time were analyzed, both on the global and regional basis, and the parametric relationship between the statistical characteristics of 1-minute and other measurement data were investigated to deduce the conversion methods. It is shown that the global model works good with good accuracy for 5-, 10-, 20-min integration time, and the global model is also applicable globally with good accuracy for 5-, 10-, 20-min integration time. The global conversion model was adopted last year as an ITU-R document for new recommendation. The regional conversion model would also be very useful for locations of similar climatic zone.

Measurements of path loss in MM-wave for indoor environments

In the indoor environment, millimeter wave channel will be probably limited in the indoor environment due to severe attenuations by furniture, partitions, walls, and floors for non line of sight (NLOS). Therefore, in order to analysis a radio system at millimeter wave bands we need to measure path loss characteristics of a millimeter wave indoor channel, the influence of geometry on this phenomenon. In this paper, the path loss model using the statistical method based on the measurement was proposed. This model consists of three parts, free space path loss, attenuation factor and excess loss. To estimate the propagation characteristics has been measured path loss in the indoor environments using omni and horn antenna for line of sight (LOS) and non line of sight (NLOS). From the measurements results, we are proposed attenuation factor and standard deviation. Also, we compare the proposed attenuation factor with other reference model and analyze the delay characteristics for MM -wave

60 and 28GHz delay spread measurements and simulation at indoor.

Millimeter-wave has been used for high transmission rate fixed communication in line of sight and short range without problems due to multipath reflections. But if it is used for mobile communications, such as WLAN using at 60GHz and 5G using at 28GHz, the delay spread made of multipath reflections limits the transmission rate. The delay spread characteristics were measured in an empty office room with only a partition for nonline of sight (NLOS), and compared the measured and simulated results of ray-tracing method at 60GHz. Finally, we suggested a method to study the delay spread characteristics at 28GHz for 5G service.

Channel Correlation Analysis using MIMO Channel Measurement Parameters at Domestic 700MHz band

In the next generation of mobile communication systems, high data rates and high capacity will be possible if multiple antennas are used at new frequencies. This paper presents the correlations between channel parameter path loss (PL), delay spread (DS), angular spread (AS) and K-factor established based on channel measurements. To avoid interference from Korean DTV broadcasting, we measured the channel characteristics in urban/rural/suburban areas on Jeju Island using a channel sounder and antennas. The correlations between channel parameter show that the wireless channel characteristics can be determined and effective communication system design can be produced for use in similar environments.

MIMO Radio Channel Measurement and Analysis at 781MHz

Abstract In this paper, the measurement data is analyzed and channel parameters are derived through MIMO Channel measurements at 781MHz considering outdoor multi-path environment. 781MHz frequency band currently operates the DTV system. However, it will be allocated new mobile communication frequency band. The channel characteristics at 781MHz seem to be similar existing mobile communication system at 900MHz but a study on channel characteristics of signal transfer process is necessary because there is incomplete study in mobile networks at 781MHz. To avoid interference with Korean DTV broadcasting, we measured channel characteristics in city/suburban areas of Jeju island by channel sounder and 4×4 antenna of the ETRI(Korea Electronics and Telecommunications Research Institute). Path Loss, Delay Spread, Angular Spread and K-factor were derived based on measured data. Key Words : MIMO, Path Loss, Delay Spread, Angular Spread, K-factor * 준회원, 충북대학교 전파공학과 ** 준회원, 한국전자통신연구원 전파기술연구부 ***

MIMO Channel Measurement and Analysis for 4G Mobile Communication

MIMO channel model requires propagation channel measurements to estimate according channel parameters and is rarely done. This paper presents the measured radio propagation characteristics in outdoor environments for 4G mobile communication in the Jeju Island at 781 MHz frequency. 781MHz frequency band currently operates the DTV system, however, it will be allocated 4G mobile communication frequency band. So, we measure channel characteristics in urban/rural/suburban areas by 4×4 MIMO channel sounder. To analyses the frequency characteristics for a domestic propagation environment, we derive various propagation characteristic parameters.

Enhancement approach of ray-tracing algorithm for propagation prediction at the MM-wave band

The reflection characteristics of building materials at the millimeter (MM) wave band are needed for development MM-wave application such as Giga-bytes indoor communication systems. Because reflection characteristics in the MM-wave band is dependent on the condition of measurement environments and has so little measurement data. To enhance these problems, we have studied propagation characteristics in the MM-wave band. In this paper, we set up the measurement system and measured the propagation characteristics of samples with periodic and random rough surfaces. Their results compared with measurement and simulation results at the 60 GHz. We have numerical simulation for dependence of electrical property. Also, the energy estimation of scattered reflection according to the rough surfaces simulated. Finally, we propose the simple approach (2 ray path model) for ray-tracing algorithm. This approach can be directly applied to the estimation of multipath signal strength in ray tracing by weighting factor for propagation prediction.

Radio propagation characteristics in the large city and LTE protection from STL interference

This paper describes composite propagation effects of both the median pathloss and shadow fading in the large city. In general, the propagation characteristic for the power profile of received signal has the relative power reduction and fluctuation according to distance to the receivers location far away from the transmitter. The result of these channel propagation losses is due to the reduction of electric field in the air according to the separated distance between a transmitter and receiver, and due to the multipath effect such as the plane reflection and edge diffraction of the propagated radio signals at the plane of buildings and roads or vehicles etc. Propagated multipath radio signals via different paths may be simultaneously received to a target receiver with different field strength and phases. Actually, it is not easy to how to predict the optimum radio propagation characteristics in the large city from a transmitter to target receiver at the specific mobile or fixed communication link, because the outdoor environment have the different height of transceivers and various structure factors such as buildings, roads, and vehicles in the large city including the urban, suburban and rural area. Therefore, the measurement is currently candidate solution for predicting the radio propagation characteristics in the novel environments. In this paper, two different stations between a fixed and mobile station are considered. Measurement results are compared with the general radio propagation model of 3GHz frequency and lower. As another issue, we discuss and propose on the closed form of the interfering received signal strength intensity when two different stations like a fixed system as the repeater and a mobile system as Long Term Evolution coexist in the same area. In the coexisting environment, two different stations overlap the cell coverage and are assigned in the adjacent channel frequency. Therefore, the potential interference may cause to their reception each other. Here, it is important to analyze the interference impact to the victim station as a receiver from the interfering station as a transmitter to get out of the interference. In this paper, it is assumed that an interfering station as a transmitter is fixed repeater and a victim station as a receiver is a mobile Long Term Evolution system. For estimating interfering received signal strength intensity, it is issued to figure out a radio propagation characteristic. However, it is unknown for the available median pathloss model to apply for analyzing the performance of Long Term Evolution system from interfering fixed repeater in the large city with none line of sight in the coexisting environment. Finally, we propose the median pathloss characteristic from measuring the electric field strength of a fixed repeater as an interfering transmitter and calculated interfering received signal strength intensity to a victim station. Using both the measurement and the theoretic calculation results, the separated distance between an interfering transmitter and victim receiver is discussed for the protection of a victim station.

Analysis of reflection and scattering characteristics at the 60GHz frequency

This paper presents the analysis result of reflection and scattering characteristics for propagation prediction at the 60GHz frequency. Because the millimeter wave band has very short wavelength within a few millimeter, the scattering characteristic is occurred by the small roughness of the surface of a wall on indoor environment. In addition, because the propagation characteristics appear differently by the surface roughness of mediums, the propagation prediction is very difficult. Therefore, the scattering characteristics according to the surface roughness should be analysed for accurate propagation prediction. To predict the propagation characteristics in the indoor environments, we should have studied changes in the accordance with the rough surface. This paper analyses the reflection and scattering characteristics by the surface roughness of mediums in millimeter wave band, and studies the method for applying to the propagation prediction.

The measurements of rain attenuation for terrestrial link at millimeter Wave

This paper presents 1-year measurements of rain attenuation versus rain rates at 0.5 km line-of-sight terrestrial link using millimeter wave. The rain attenuation according to rain rate is compared to the ITU-R model. Due to the measurements we have large difference compared to ITU model the attenuation statistics in the millimeter wave.