Shigenori Tani

An Adaptive Beam Control Technique for Q Band Satellite to Maximize Diversity Gain and Mitigate Interference to Terrestrial Networks

The earth observation missions have been improved its sensor performance which results in a huge amount of data to be stored in remote sensing satellite and transmitted to a ground station. Although, satellite to ground transmitter had been usually used X band, several mitigation techniques for rain attenuation have been studied in recent years to migrate to Ka band for broadband transmission. Furthermore, Q band is expected to achieve higher data rate because of its broader bandwidth. However, Q band is shared with terrestrial networks, remote sensing satellite has to take into account potential constrains to them. Therefore, this paper addresses remote sensing satellite network and proposes novel beam control technique to coexist with the terrestrial networks in Q band. The proposed method controls satellites transmitting antenna boresight adaptively to maximize signal to noise power ratio of satellite ground station and minimize interference to terrestrial networks. The effectiveness of our proposal is verified through simulation results.

An adaptive beam control technique for diversity gain maximization in LEO satellite to ground transmissions

The earth observation missions have improved its sensor performance, it results in a huge amount of data to be stored and transmitted to a ground station. Although, satellite to ground transmitter had been usually used X band, migration to Ka band has been studied in recent years for broadband transmission. Relative to X band, higher frequency has severe atmospheric effects, site diversity is one of the popular technique to mitigate rain attenuation. However, if Signal to Noise power Ratio (SNR) is different between receivers because of receiving antenna gain and rain attenuation, diversity gain decreases. This paper proposes novel beam controlling method to improve SNR performance for satellite to ground transmission. The proposed method estimates SNR in each of candidate transmitting antenna boresight, and update boresight in order to be equal SNR between receivers. Simulation results show that, proposed method improves SNR especially at a low elevation angle.

Flexibility-Enhanced HTS System for Disaster Management: Responding to Communication Demand Explosion in a Disaster

Natural disaster interrupts essential services due to the facility damage and lack of power supply. Especially, significant communication outages occurs in a wide area for hierarchical network such as cellular communication system in case core nodes are damaged or congested. In order to provide alternative communication ability, high throughput satellite (HTS) is one of the ideal candidates for disaster management because it provides operative communication for a wide area regardless of the availability of regular terrestrial infrastructures. However, conventional HTS relays data with predetermined beam bandwidth and connection, it is inefficient when the communication demand explodes in a disaster area. Therefore, this paper proposes novel frequency allocation technique with flexibility-enhanced HTS system for disaster management to respond to communication demand explosion. While related research works consider user-link resource allocation, this paper focuses on how to control feeder-link and user-link bandwidths in case that the both links can be assigned at continuous frequency such as Ka-band. Furthermore, our proposal addresses resilient satellite network by selecting optimum gateway based on the traffic demand at neighboring user-link beams. The effectiveness of our proposal is verified through simulation results.

Performance Evaluation of a Ka-band Satellite Communication Subsystem Using Pre-distortion Techniques

The observation capabilities of Earth observing satellites have grown. To increase data transmission speeds, we have investigated a Ka-band data downlink system for Earth observing satellites. One of the most important components of the onboard Ka-band communication subsystem is the RF power amplifier which has the greatest power consumption. Linearization using distortion compensation techniques reduces the amplifier’s output power back-off and enables the utilization of 16-quadrature amplitude modulation (16-QAM) signals, which are more sensitive to linear and non-linear distortion than quadrature phase shift keying signals. This paper describes the performance evaluation of a Ka-band satellite communication subsystem using pre-distortion techniques by both simulation and experiment. It was demonstrated that pre-distortion could reduce the output power back-off of the amplifier by 2.2 dB under the same error vector magnitude of the 16QAM signal.