Koya Sato

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Spectrum sharing with cognitive radio (CR) has attracted attention to solve the shortage of spectrum resources. In a spectrum sharing environment, secondary users (SUs) can utilize spectrum bands which are licensed to primary users (PUs) under interference constraint at PUs. In order to gain the spectrum sharing efficient by setting suitable communication(More)
In this paper, we propose an interference power constraint method using measurement-based spectrum database for high efficient spectrum sharing. The spectrum database is constructed from measurement radio environment information measured by secondary users (SUs) with mobility, and stores radio environment maps (REMs). This paper focuses on a database-aided(More)
This paper proposes a parameter estimation method of primary user using geographical spectrum database consisting of measurement results gathered by secondary nodes. Compared to Model-based database such as FCC's database, the proposed method may enable higher accuracy spectrum sharing between secondary and primary users. Through the measurement experiment,(More)
In this paper, we propose a scheduling method with successive interference cancellation (SIC) for vehicle to vehicle (V2V) networks to improve the reliability and the capacity. SIC is a multi-user detection technique that repeatedly decodes the multiple signals by cancelling the strongest signal by using the detected signal in the previous step. In the(More)
The social tagging system allows users to add arbitrary strings, namely 'tags', on a shared resource to organise and manage information. The Yule–Simon process, which is known to capture the population dynamics of social tagging behaviour, does not handle the mechanism of new vocabulary creation because this model assumes that new vocabulary creation is a(More)
In order to fill the gap between various levels of ball game players, we propose the Sports Support System that can reduce the difference among the skills of various players by augmenting the traditional ball game. We implemented a system that visualizes the trajectory and velocity of the ball for soccer games, as one example of ball games. This(More)
SUMMARY In this paper, we propose the novel concept of a spectrum database for improving the efficiency of spectrum utilization. In the current design of TV white space spectrum databases, a propagation model is utilized to determine the spectrum availability. However, this propagation model has poor accuracy for radio environment estimation because it(More)