arXiv subjects

Shigemi Ishida

Publications and source records attributed to Shigemi Ishida.

4 recordsLinked to original sources

arXiv2026

Packet Interval Modulation-based NFC for Scalable IoT around Meandered E-textile

Near-field communication (NFC) sensor tags are promising for low-cost, scalable environmental monitoring due to their battery-free, maintenance-free operation. Recent advances in NFC reader garments, integrated with conductive textile coils, allow users to interact seamlessly with tags scattered across their daily environment. However, dynamically identifying and reading out a fluctuating number of tags remains challenging. If multiple tags speak and collide, they must randomly retry until an empty slot is found. Standard NFC identifies tags using time-slotted ALOHA, which assigns tags to fixed time slots. If multiple tags speak and collide, they must retry with a tag filter to avoid collision until all tags are identified. This rigid setup is fragile in dynamic settings; as tags enter and leave the communication range, the heavy overhead of slot re-negotiation and inevitable collisions restricts data throughput. Here, we propose an asynchronous NFC based on packet interval modulation. By treating minimal ID-only packets as pulses and encoding data in their intervals, we enable communication through silence. This ensures the channel remains mostly unoccupied, drastically reducing collisions even in high-density environments. Our simulations show that for ten tags, our method achieves a 4-fold increase in throughput compared to the ALOHA approach. Furthermore, the system remains robust, maintaining over 160 bps/tag throughput even under extreme fluctuations in the number of tags over 20.

cs.NI↗

arXiv2025

Ultra-low-power ring-based wireless tinymouse

Wireless mouse rings offer subtle, reliable pointing interactions for wearable computing platforms. However, the small battery below 27 mAh in the miniature rings restricts the ring's continuous lifespan to just 1-10 hours, because current low-powered wireless communication such as BLE is power-consuming for ring's continuous use. The ring's short lifespan frequently disrupts users' mouse use with the need for frequent charging. This paper presents picoRing mouse, enabling a continuous ring-based mouse interaction with ultra-low-powered ring-to-wristband wireless communication. picoRing mouse employs a coil-based impedance sensing named semi-passive inductive telemetry, allowing a wristband coil to capture a unique frequency response of a nearby ring coil via a sensitive inductive coupling between the coils. The ring coil converts the corresponding user's mouse input into the unique frequency response via an up to 449 uW mouse-driven modulation system. Therefore, the continuous use of picoRing mouse can last approximately 600 (8hrs use/day)-1000 (4hrs use/day) hours on a single charge of a 27 mAh battery while supporting subtle thumb-to-index scrolling and pressing interactions in real-world wearable computing situations.

cs.HC↗

arXiv2022

ZEL: Net-Zero-Energy Lifelogging System using Heterogeneous Energy Harvesters

We present ZEL, the first net-zero-energy lifelogging system that allows office workers to collect semi-permanent records of when, where, and what activities they perform on company premises. ZEL achieves high accuracy lifelogging by using heterogeneous energy harvesters with different characteristics. The system is based on a 192-gram nametag-shaped wearable device worn by each employee that is equipped with two comparators to enable seamless switching between system states, thereby minimizing the battery usage and enabling net-zero-energy, semi-permanent data collection. To demonstrate the effectiveness of our system, we conducted data collection experiments with 11 participants in a practical environment and found that the person-dependent (PD) model achieves an 8-place recognition accuracy level of 87.2% (weighted F-measure) and a static/dynamic activities recognition accuracy level of 93.1% (weighted F-measure). Additional testing confirmed the practical long-term operability of the system and showed it could achieve a zero-energy operation rate of 99.6% i.e., net-zero-energy operation.

cs.HC↗

arXiv2017

Free Side-channel Cross-technology Communication in Wireless Networks

Enabling direct communication between wireless technologies immediately brings significant benefits including, but not limited to, cross-technology interference mitigation and context-aware smart operation. To explore the opportunities, we propose FreeBee -- a novel cross-technology communication technique for direct unicast as well as cross-technology/channel broadcast among three popular technologies of WiFi, ZigBee, and Bluetooth. The key concept of FreeBee is to modulate symbol messages by shifting the timings of periodic beacon frames already mandatory for diverse wireless standards. This keeps our design generically applicable across technologies and avoids additional bandwidth consumption (i.e., does not incur extra traffic), allowing continuous broadcast to safely reach mobile and/or duty-cycled devices. A new \emph{interval multiplexing} technique is proposed to enable concurrent bro\-adcasts from multiple senders or boost the transmission rate of a single sender. Theoretical and experimental exploration reveals that FreeBee offers a reliable symbol delivery under a second and supports mobility of 30mph and low duty-cycle operations of under 5%.

cs.NI↗