Hideki Omote

Empirical Time-Spatial Propagation Model in Outdoor NLOS Environments for Wideband Mobile Communication Systems

In order to accurately evaluate spatial processing techniques such as Adaptive Array Antenna and MIMO techniques for wideband mobile communications, we require a time-spatial propagation model which allows the delay profile and spatial arrival angular profile characteristics of the travelling wave to be analyzed at the same time. In this paper, we propose an empirical time-spatial propagation model based on a heuristic formula estimated from field measurement data obtained in urban and suburban areas.

Empirical Time-Spatial Propagation formula for outdoor LOS environments

In order to accurately evaluate spatial processing techniques such as MIMO for wideband mobile communications, a Time-Spatial Propagation (TSP) model that can simulate the characteristics of both the delay profile and the spatial arrival angular profile for travelling waves at the same time is required. We proposed the TSP model for wideband mobile communication systems using UHF and SHF bands in Non-line of sight (NLOS) environments. Based on field measurement data, this paper extends the TSP model for NLOS environments to create an empirical TSP model for Line of Sight (LOS) environments.

Empirical Arrival Angular Profile Prediction Formula for Mobile Communication Systems

Arrival angular profile model is necessary to evaluate accurately the spatial processing techniques such as adaptive array antenna (AAA) and multi-input-multi-output (MIMO). Existing models do not always predict the actual values accurately in various environments. In this paper, we propose a novel empirical arrival angular profile prediction formula that can consider the distance from BS, antenna height of the base station, and city structure (building height) generated from the data measured in various field environments. As the proposed formula is a relatively simple equation and can predict the spatial correlation accurately, it is convenient and useful for evaluating the characteristics of radio transmission systems such as MIMO and AAA, etc. in various areas.

Arrival Angular Profile Modeling at Mobile Station for Cellular Systems

Spatial processing techniques such as Adaptive Array Antenna (AAA) and Multi-Input-Multi-Output (MIMO) are being considered for use in the next generation mobile cellular systems. In order to accurately estimate the performance of these spatial processing techniques in wide-band mobile communications, we need a time-spatial path model that can present the delay profile and the spatial arrival angular profiles at the same time. We proposed a physical time-spatial path model as a variant of Clarks scattering model and showed by theory and by computer simulation that the proposed model can well match field measurement results with regard to the arrival angular distribution at the BS and the delay time distribution in urban and suburban areas by setting key parameters to appropriate values. In this paper, we propose an empirical arrival angular profile model at the mobile station (MS). First we derive an arrival angular profile model at the MS based on our proposed physical time-spatial path model. Then we optimize the parameters of the model by using field data measured in suburban and urban areas in Tokyo.

Arrival Angular Profile Modeling at Mobile Station for Outdoor NLOS and LOS Environments

Spatial processing techniques such as Adaptive Array Antenna (AAA) and Multi-Input-Multi-Output (MIMO) are being considered for use in next generation mobile cellular systems. In order to accurately estimate the performance of these spatial processing techniques in wide-band mobile communications, we need an arrival angular profile model at both the base station (BS) and the mobile station (MS). We proposed empirical arrival angular profile model at both the BS and the MS in Non-line of sight (NLOS) environments. Further, we proposed an empirical arrival angular profile model at the BS in Line of Sight (LOS) environments. To complete the arrival angular profile model at the MS, we need to cover LOS environments. Based on field measurement data, this paper extends the arrival angular profile model at the MS in NLOS environments to create a variant that also covers LOS environments. The extended model can predict the arrival angular profile at the MS in both LOS and NLOS environments.

Predicting the K-Factor of Divided Paths in Wideband Mobile Propagation

In order to design wideband mobile communication systems, we must analyze the multi-path propagation characteristics more accurately. The distribution of received power in mobile communication systems is well known to follow a Nakagami-Rice distribution with the key parameter being the K-factor. When the K-factor is set to 0, the Nakagami-Rice distribution equals a Rayleigh distribution. Wideband wireless systems can divide multi-paths into delay paths and improve the communication quality by combining the delay paths effectively. Therefore, in wideband mobile communication systems, it is more important to calculate the K-factor than the distribution of each delay path. In this paper, we clarify the relation between excess delay time and the K-factor of each delay path and introduce an empirical formula that predicts the K-factor as a function of excess delay time.

A Balloon-Based Wireless Relay System for Disaster Response

When a disaster occurs, various initiatives are often carried out to rapidly restore mobile communication to service areas where communication failures have occurred. As one such initiative, we have developed a balloon-based wireless relay system in which a non- regenerative wireless repeater is installed on a balloon. Through our experimentation, we confirmed that coverage within a 5 km radius was successfully achieved. In this paper, we present an overview of our balloon-based wireless relay system and the means to its deployment.

Delay Profile Model for Low Antenna Height Base Stations in Broadband Mobile Communication

Small cells such as micro and pico cells, whose BS antennas are lower than neighboring buildings, are being installed to suppress co-channel interference. Thus a time spatial propagation (TSP) model that predicts, at the same time, the delay profile and spatial arrival angular profile characteristics of the traveling waves for low- antenna-height BSs, is strongly required. This paper proposes an empirical delay profile prediction formula for low-antenna-height BSs that takes account of BS antenna height, distance from BS and city structure.

Carrier Frequency Characteristic of Time-Spatial Profile in Outdoor LOS Environments

In order to evaluate spatial processing techniques such as MIMO for wideband mobile communications, a Time-Spatial Propagation (TSP) model is required. The Time-Spatial profile consists of the delay profile, the spatial arrival angular profiles at the base station (BS) and the mobile station (MS) for traveling waves. One key parameter of the TSP model is carrier frequency. We have proposed a Time-Spatial profile prediction formula for wideband mobile communication systems in Non-line of sight (NLOS) environments and clarified that the Time-Spatial profile does not depend on the carrier frequency. We have also carried out measurements to develop the Time-Spatial profile prediction formula for Line of sight (LOS) environments. In this paper, we evaluate the carrier frequency characteristics of the Time-Spatial profile in Line of sight (LOS) environments based on the measurement data, and show that our proposed Time-Spatial profile prediction formula in LOS environments is valid for various carrier frequencies.

Time-Spatial Path Modeling with Multi-Scattering Attenuation Factors for Wideband Mobile Propagation

In order to accurately assess spatial processing techniques such as adaptive array antenna (AAA) and MIMO for wideband mobile communications, we proposed a time-spatial path model that allows the delay profile and angle profile of the traveling wave to be simulated at the same time. In order to explain the field measurement results in various environments, this paper proposes an advanced time-spatial path model that uses several attenuation factors instead of the one attenuation factor used in our previous proposal