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Tetsuya Kawanishi

Publications and source records attributed to Tetsuya Kawanishi.

2 recordsLinked to original sources
arXiv2026

Experimental Verification on LoS-MIMO Transmission in 300-GHz Band

In this study, we conducted Line-of-Sight (LoS) 2x2 multiple-input multiple-output (MIMO) orthogonal frequencydivision multiplexing (OFDM) transmission experiments in the 300-GHz band to investigate the potential for channel capacity enhancement. A circularly polarized patch antenna, supporting both crossand co-polarization, and a 2x2 MIMO transceiver equipped with a Pre-Correction scheme were developed. Experimental evaluation was carried out under conditions of a stream spacing of 0.3 m and a transmission distance of 1.9 m. As a result, in both coand cross-polarized antenna configurations, the off-diagonal components were suppressed below -20 dB, and 2-stream transmission with 16-QAM modulation achieved a throughput of 13.1 Gbit/s and a spectral efficiency of 6.55 bit/s/Hz. Furthermore, future research directions toward advanced spatial multiplexing based on channel correlation analysis are discussed. These results demonstrate the feasibility of highcapacity fixed wireless links and provide practical design insights for long-distance transmission.

eess.SP↗
arXiv2001

Optimum detection for extracting maximum information from symmetric qubit sets

We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have been predicted by Sasaki et al. [Phys. Rev. A{\bf 59}, 3325 (1999)]. The peculiar aspect is that the detections with at least three outputs suffice for optimum extraction of information regardless of the number of signal elements. The cases of ternary (or trine), quinary, and septenary polarization signals are studied where a standard von Neumann detection (a projection onto a binary orthogonal basis) fails to access the maximum information. Our experiments demonstrate that it is possible with present technologies to attain about 96% of the theoretical limit.

quant-ph↗