Naganori Shirakata

BAN Radio Link Characterization Using an Arm-Swinging Dynamic Phantom Replicating Human Walking Motion

This paper presents a newly developed arm-swinging dynamic phantom that can simulate human walking and running motions. The arm-swinging phantom has unique features, in that swinging of the right and left arms and the direction and speed of swing can be controlled independently, leading to excellent capability for replicating the variety of natural walking and running styles seen in the average human. Using the phantom, we have attempted to develop a dynamic channel characterization for BAN systems, such as shadowing properties and path loss characteristics, when the geometrical relationships between the arms and the human body change continuously due to the movement of the arms for both off-body and on-body situations. Assessments of communication quality, such as the signal bit error rate, were also conducted to gain useful knowledge of the way and the degree to which arm-swinging might impact the performance of body-attached BAN devices. Analytical results are also shown for the case where the combined outcome of shadowing and multipath fading emerge simultaneously when a human walks in a multiple radio wave propagation environment while swinging both arms.

A 60GHz wireless transceiver employing hybrid analog/digital beamforming with interference suppression for multiuser gigabit/s radio access

This paper presents a 60GHz analog/digital beamforming transceiver that effectively suppresses interference signals, targeting WiGig/IEEE 802.11ad standard. A prototype has been built with 40nm CMOS analog front-ends as well as offline baseband digital signal processing. Measurement shows 3.1dB EVM advantage over the conventional two-stream diversity during a packet collision situation.

A 6.16Gb/s 4.7pJ/bit/iteration LDPC decoder for IEEE 802.11ad standard in 40nm LP-CMOS

This paper presents an LDPC decoder employing a column-parallel architecture that enables low-power and high-speed operation suitable for the 802.11ad standard. As compared to the conventional row-parallel architecture, the proposed architecture reduces the required memory size by 60% and also minimizes the number of pipeline stages for high throughput operation. Fabricated in 40nm LP CMOS technology, the prototype achieves high energy efficiency of 4.7pJ/bit/iteration for 6.16Gb/s while supporting all the modulation and coding schemes (MCS0 to MCS12) required for the 802.11ad single-carrier (SC) modulation.

IEEE 802.11ad/WiGig based millimeter-wave small cell systems with adjacent channel interference suppression

This paper presents a study on adjacent channel interference in millimeter-wave small cell systems based on IEEE 802.11ad/WiGig. It includes hardware prototype development, interference measurements, and performance evaluation of an interference suppression technique. The access point prototype employs three RF modules with 120° beam steering capability, thus enabling 360° coverage. Using the developed prototype, interference measurements were performed and the packet error degradation due to adjacent channel interference was observed. To mitigate the performance degradation, an interference suppression technique using a two stream receiver architecture was applied. The subsequent measurements showed improvement in EVM and also expansion of the cells coverage area, demonstrating the effectiveness of the applied technique for small cell systems using IEEE 802.11ad/WiGig.