60 GHz technology holds tremendous potential to upgrade wireless link throughput to Gbps level. To overcome inherent vulnerability to attenuation, 60 GHz radios communicate by forming highly-directional electronically-steerable beams. Standards like IEEE 802.11ad have tailored MAC/PHY protocols to such flexible-beam 60 GHz networks. However, lack of a reconfigurable platform has thwarted a realistic proof-of-concept evaluation. In this paper, we conduct an in-depth measurement of indoor 60 GHz networks using a first-of-its-kind software-radio platform. Our measurement focuses on the link-level behavior with three major perspectives: (i) coverage and bit-rate of a single link, and implications for 60 GHz MIMO; (ii) impact of beam-steering on network performance, particularly under human blockage and device mobility; (iii) spatial reuse between flexible beams. Our study dispels some common myths, and reveals key challenges in maintaining robust flexible-beam connection. We propose new principles that can tackle such challenges based on unique properties of 60 GHz channel and cognitive capability of 60 GHz links.

Abstract-Coordination of co-located wireless devices is a fundamental function/requirement for reducing interference. However, different devices cannot directly coordinate with one another as they often use incompatible modulation schemes. Even for the same type (e.g., WiFi) of devices, their coordination is infeasible when neighboring transmitters adopt different spectrum widths. Such an incompatibility between heterogeneous devices may severely degrade the network performance. In this paper, we introduce Gap Sense (GSense), a novel mechanism that can coordinate heterogeneous devices without modifying their PHYlayer modulation schemes or spectrum widths. GSense prepends legacy packets with a customized preamble, which piggy-backs information to enhance inter-device coordination. The preamble leverages the quiet period between signal pulses to convey such information, and can be detected by neighboring nodes even when they have incompatible PHY layers. We have implemented and evaluated GSense on a software radio platform, demonstrating its significance and utility in three popular protocols. GSense is shown to deliver coordination information with close to 100% accuracy within practical SNR regions. It can also reduce the energy consumption by around 44%, and the collision rate by more than 88% in networks of heterogeneous transmitters and receivers.

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Millimeter-wave (mmWave) technology is emerging as the most promising solution to meet the multi-fold demand increase for mobile data. Very short wavelength, high directionality, together with sensitivity to rampant blockages and mobility, however, render state-of-the-art mmWave technologies unsuitable for ubiquitous wireless coverage. In this work, we design and implement UbiG-a mmWave wireless access network-that can deliver ubiquitous gigabits per second wireless access consistently to the commercial-off-the-shelf IEEE 802.11ad devices. UbiG has two key design components: (1) a fast probing based beam alignment algorithm that can identify the best beam consistently with guaranteed latency in a mmWave link, and the algorithm scales well even with a very large number of beams; and (2) an infrastructure-side predictive ranking based fast access point switching algorithm to ensure seamless gigabits per second connectivity under mobility and blockage in a dense mmWave deployment. Our IEEE 802.11ad testbed experiments show that UbiG performs close to an "Oracle" solution that instantaneously knows the best beam and access point for gigabits per second data transmission to users.