Tomoya Urushihara

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.

Accurate UMTS power transition with power alignment loop between two different modulation modes for polar transmitters

Generally low power region is very dominant for current consumption on UMTS handsets. However, a polar modulation architecture has a little bit lager current consumption in this region. So, we propose polar/quadrature modulation architecture with a fast-feedback power control technique “power alignment loop (PAL)”. The PAL can realize accurate UMTS power transition over the two different modulation modes. Measurement results shows that the power accuracy between the two modes can satisfy the 3GPP standard within 25 µs from the slot boundary. The average current consumption of the transmitter is 128 mA at the battery.

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.