Yoichiro Watanabe

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The necessary and sufficient condition of the channel capacity is rigorously formulated for the N -user discrete memoryless multiple-access channel (MAC). The essence is to invoke an elementary MAC where sizes of input alphabets are not greater than the size of output alphabet. The main objective is to demonstrate that the channel capacity of an MAC is(More)
User identification by signature code is considered for noisy multiple-access adder channel. An n/2-decodable signature code is developed from a Hadamard matrix of order n. The code is used to identify users through the multiple-access adder channel even in the presence of channel noise. A decoding rule is provided to correct lfloor(n/2 - 1)/2rfloor errors(More)
Under-recognition of depression is common in many countries. Education of medical staff, focusing on their attitudes towards depression, may be necessary to change their behavior and enhance recognition of depression. Several studies have previously reported on attitudes toward depression among general physicians. However, little is known about attitudes of(More)
A simple DoA estimator is proposed with a switched beam antenna. The estimator is implemented with an adjacent pattern power ratio algorithm. For a single source signal, the received signal powers are measured while the antenna switches over a set of measured directive beam patterns. The pattern that exhibits the maximum received signal power is chosen.(More)
— Adaptive beamforming with Hamiltonian algorithm is proposed for ESPAR antenna. Hamilton's equations describing the motion of particles are used to solve optimization problems. In an application of Hamiltonian algorithm to ESPAR antenna, the cost function for beamforming is considered as the potential energy. Although the kinetic energy, acted by(More)
A relay scheme combining network coding with channel coding is proposed for multiple-access relay channel. Via a newly designed network low density parity check code, this scheme permits the relay node to jointly encode the data information from two source nodes. To predict the system performance, a newly generalized Gaussian approximation algorithm is(More)