Millimeter wave communications : from point-to-point links to agile network connections

Abstract

Millimeter wave (mmWave) technologies promise to revolutionize wireless networks by enabling multi-gigabit data rates. However, they suffer from high attenuation, and hence have to use highly directional antennas to focus their power on the receiver. Existing radios have to scan the space to find the best alignment between the transmitter's and receiver's beams, a process that takes up to a few seconds. This delay is problematic in a network setting where the base station needs to quickly switch between users and accommodate mobile clients. This research encompasses the implementation and testing of Agile-link, the first mmWave beam steering system that is implemented and evaluated on phased arrays, and demonstrated to find the correct beam alignment without scanning the space. Instead of scanning, Agile-link hashes the beam directions using a few carefully chosen hash functions. It then identifies the correct alignment by tracking how the energy changes across different hash functions. Two major limitations are addressed in this research. First is the issue of delays in scanning and the second is the accuracy of the beams. Here we propose, implement and examine solutions to these two major issues. Our results show that not only does Agile-link create accurate phase shifted beams, but, it also reduces beam steering delay by orders of magnitude.