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Low latency is a requirement for a variety of interactive network applications. The Internet, however, is not optimized for latency. We thus explore the design of wide-area networks that move data at nearly the speed of light in vacuum. Our cISP design augments the Internet’s fiber with free-space microwave wireless connectivity over paths very close to great-circle paths. cISP addresses the fundamental challenge of simultaneously providing ultra-low latency while accounting for numerous practical factors ranging from transmission tower availability to packet queuing. We show that instantiations of cISP across the United States and Europe would achieve mean latencies within 5% of that achievable using great-circle paths at the speed of light, over medium and long distances. Further, using experiments conducted on a nearly-speed-of-light algorithmic trading network, together with an analysis of trading data at its end points, we show that microwave networks are reliably faster than fiber networks even in inclement weather. Finally, we estimate that the economic value of such networks would substantially exceed their expense. 

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.