Yoshiaki Amano

KDDI Research · Radio Spectrum Laboratory

To realize dynamic spectrum sharing, it is necessary to avoid interference from the secondary system to the primary system. Technical information such as the position of the radio station and the antenna specification of the primary system are required to estimate interference to the primary system accurately, but these specifications are not gener...

In order to improve the efficiency of spectrum use, systems that share spectrum while avoiding interference between different systems are being investigated. In the millimeter-wave band, which is expected to be utilized in the future, the received power fluctuates due to quasi-static obstructions such as people and vehicles, but such temporal varia...

For the efficient use of frequency resources, dynamic spectrum allocation (DSA) between different radio systems is promising. In DSA, our approach is to allow different mobile network operators to use the same shared channel without the inter base station (BS) interference. However, this approach is computationally very expensive. Therefore, we for...

Multi-input multi-output (MIMO) transmission with multiple antennas, which performs parallel transmission at the same time and frequency and enhances the channel capacity, has attracted attention. In the case of small mobile terminals, the limitation of spaces for the multiple antennas leads to degrade the improvement of the channel capacity in pro...

MIMO channel emulation systems have been studied and developed to achieve the evaluation for the MIMO transmission technique of user equipments (UEs) with multiple antennas. The system can generate a multipath with a spatial signature by transmitting signals from multiple probe antennas set around the UE. The resolution of the emulated spatial dist...

This paper demonstrates the effectiveness of an adaptive impedance control for mobile terminals with MIMO antennas, which aims to improve the antenna performance in the usage environment, over an FDD-LTE (Frequency Division Duplex - Long Term Evolution) system through experimental measurement by using a developed prototype terminal. Measurement res...

In this paper, we evaluate the antenna performance with the distributed terminals in the scenario, as well as in the free space, in order to show the effectiveness of the distributed MIMO antenna architecture through the comparison to a single terminal by the computer simulation. Concretely, main and sub terminals, respectively with two antennas, a...

This paper presents an adaptive impedance control of antennas on user equipment (UE) for a Long Term Evolution (LTE) system that supports MIMO reception in downlink and single antenna transmission in uplink. The proposed control method balances the performances of both links, duplexing with a frequency division duplex (FDD), without additional info...

This paper proposes an adaptive impedance control for MIMO (Multiple Input Multiple Output) antennas and evaluates its basic performance in a realistic environment of usage of the compact mobile device through a computer simulation modeled with a 3D antenna radiation pattern including the human body effect and MIMO propagation channel. The control...

Measurement of radio frequency (RF) radiation performance has been investigated for mobile terminals including the influence of the human body. As presented by smart-phone growth, mobile terminals are used not only in talk but also various other positions such as browsing, jogging, and so on. Therefore, a phantom corresponding to various positions...

In this paper, an omni-directional slim polarization diversity antenna for cellular system is designed. The vertical polarization antenna with substrate construction and the horizontal polarization antenna with cylindrical construction match well. The configuration of polarization diversity antenna is optimized by E-field distribution and high isol...

This paper proposes a new transmitter architecture that enables concurrent transmission of two separate frequency bands. This is required in order to realize a spectrum aggregation system. The architecture is based on a delta-sigma (¿¿) modulation which converts a non-constant envelope signal into a constant one. This enables the transmitter to e...

Measurement of radio frequency (RF) radiation performance has been investigated for mobile terminals including the influence of the human body. Recent studies have shown that the user's hand has a greater influence on antenna radiation performance than the head. Therefore, a hand phantom needs to be included in the evaluation of the RF performance...

In this paper, a thin vertical polarization antenna for 800 MHz band cellular system is described. The influence of radome is confirmed and both resonant frequency and bandwidth are changed by radome. It is verified that the radome behaves as dielectric substance and it contributes to antenna miniaturization. Utilizing radome, antenna miniaturizati...

In this paper, two types of dual-band receivers are proposed in order to realize the concurrent reception of two separate frequency bands for a spectrum aggregation system. The proposed receivers consist of a common intermediate frequency stage with a common oscillator and common band-pass filter. By controlling the frequency of the oscillator, the...