Ippei Kashiwagi

Time-Varying Path-Shadowing Model for Indoor Populated Environments

This paper presents a path-shadowing model for indoor populated environments that has been developed based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined using the ray-tracing method, in which moving quasi-human bodies that are modeled as cylinders with a finite height are generated in the space, and intersections of the paths with the bodies are counted. From the results, the shadowing probabilities, durations, and intervals are evaluated for each propagation path, and this shadowing process is characterized as a Markov process. This paper proposes a method that individually generates the shadowing effects on each propagation path. The measurement results of the path-shadowing characteristics using a 5.2-GHz high-resolution channel sounder are presented, and the validity of this model is confirmed. Similar measurement results using a photoelectric sensor are also presented to reinforce the channel-sounding measurement results.

A Path Shadowing Model Focused on the Effects of Human Activities in Indoor Environments

This paper presents a path-shadowing model in indoor populated environments based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined by a ray tracing method, moving quasi-human bodies modeled as a cylinder with finite height are generated in this space, and intersections of the paths with the bodies are counted. As a result, the shadowing probabilities, durations, and intervals are evaluated for each propagation path, and this shadowing process is characterized as a Markov process. This paper proposes a method for individually generating the shadowing effects on each propagation path. The results of 5.2 GHz propagation measurements in indoor populated space using a high resolution channel sounder is also presented, and the validity of this model is confirmed.

A Path Shadowing Model Representing Human Activity Effects in Indoor Environments

This paper presents a path-shadowing model in indoor populated environments based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined by a ray tracing method, moving quasi-human bodies modelled as a cylinder with finite height are generated in this space, and intersections of the paths with the bodies are counted. As a result, the shadowing probabilities, durations, and intervals are evaluated for each propagation path, and this shadowing process is characterized as a Markov process. This paper proposes a method for individually generating the shadowing effects on each propagation path. The measurement results of path shadowing characteristics using a photoelectric sensor are also presented, and the validity of this model is confirmed.

Dual-band bent-folded-monopole antenna

Recently, frequency tunable antennas with multi-band operation capability are proposed to achieve small size and high performance at the same time [1]. For example, RF switches are used in [2] to change grounding and/or feed points to shift antenna current distributions. Moreover, MEMS (Micro Electro Mechanical Systems) variable capacitor is placed on the top of an antenna element to change its electrical length to cover the wide operation band of the digital terrestrial broadcasting service [3]. These antenna structures will be effective for wideband operation, but recent increase of antenna built in mobile terminals requires smaller antennas with keeping high performance.