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This paper presents ISLA, a system that enables low power IoT nodes to self-localize using ambient 5G signals without any coordination with the base stations. ISLA operates by simply overhearing transmitted 5G packets and leverages the large bandwidth used in 5G to compute high-resolution time of flight of the signals. Capturing large 5G bandwidth consumes a lot of power. To address this, ISLA leverages recent advances in MEMS acoustic resonators to design a RF filter that can stretch the effective localization bandwidth to 100 MHz while using 6.25 MHz receivers, improving ranging resolution by 16x. We implement and evaluate ISLA in three large outdoors testbeds and show high localization accuracy that is comparable with having the full 100 MHz bandwidth. 

Interactive mobile applications like web browsing and gaming are known to benefit significantly from low latency networking, as applications communicate with cloud servers and other users’ devices. Emerging mobile channel standards have not met these needs: general-purpose channels are greatly improving bandwidth but empirically offer little improvement for common latency-sensitive applications, and ultra-low-latency channels are targeted at only specific applications with very low bandwidth requirements. We explore a different direction for wireless channel design: utilizing two channels – one high bandwidth, one low latency – simultaneously for general-purpose applications. With a focus on web browsing, we design fine-grained traffic steering heuristics that can be implemented in a shim layer of the host network stack, effectively exploiting the high bandwidth and low latency properties of both channels. In the special case of 5G’s channels, our experiments show that even though URLLC offers just 0.2% of the bandwidth of eMBB, the use of both channels in parallel can reduce page load time by 26% to 59% compared to delivering traffic exclusively on eMBB. We believe this approach may benefit applications in addition to web browsing, may offer service providers incentives to deploy low latency channels, and suggests a direction for the design of future wireless channels. 

This article introduces a new over-the-air calibration method for millimeter wave phased arrays. Our method leverages the channel estimation process which is a fundamental part of any wireless communication system. By performing the channel estimation while changing the phase of an antenna element, the response of the element is obtained. Unlike prior work, our method includes all the system components and thus, spans the full chain. By overriding channel estimation, no additional circuits are required, and online calibration is possible without pausing the communication process. We tested our method on an eight-element-phased array at 24GHz which we designed and fabricated in PCB for verification.