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Reaching the Global Classroom

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More than 1 million international students are enrolled in American universities, almost half of them from China, according to research from EducationData.org. During 2020, many of these students were required to attend classes remotely from their home countries, due to a mixture of controversial student visa policy changes, family preferences, and travel restrictions. This created large challenges for universities as they worked to reliably deliver online video instruction around the world. But these are not new challenges for either schools or students. About 350,000 U.S. university students study abroad every year, and many of them take online courses from their home university while overseas. The scale was new, though, so we were able to learn a great deal.

China provides a particularly interesting case study, due to both its huge population size and the difficulty of operating in its networks. All network traffic in China is routed through 10 national hubs. Until 2015, all Chinese internet traffic was routed through three hubs in Beijing, Shanghai, and Guangzhou; to this day, those three hubs connect the Chinese network to the global internet via undersea fiber-optic cable. Those hubs also operate the world’s most sophisticated censorship apparatus—the so-called Great Firewall of China—to block or disrupt foreign websites and internet services the government deems undesirable, most famously, all Google and Facebook products.

A consortium that includes Google and Face­book had plans to run the Pacific Light Cable Network, a 120Tbps fiber-optic cable system that was to span from Los Angeles to Hong Kong. However, those plans were scuttled by the U.S. Federal Communications Commission, and the undersea cable will stop short of Hong Kong and end at Taiwan and the Philippines. Within China, it’s illegal to host a website without a government-approved Internet Content Provider (ICP) license, and these are rarely issued to non-Chinese entities. The biggest Chinese streaming media company is iQIYI, but its ICP licenses are held by two other Chinese companies, as detailed in its 2018 IPO filing with the U.S Securities and Exchange Commission.

Given this background, how might schools reliably deliver streaming media to students in China? One option is to establish a presence within China to bypass the bottleneck of the Beijing/Shanghai/Guangzhou ingress points and firewalls. This requires a Chinese partner with an ICP license. For example, Coursera partnered with Chinese internet company Net­Ease in 2013 to host a mirror of Coursera videos within China, effectively extending its CDN beyond the firewall. Duke University struck a partnership with Wuhan University in 2011 to form Duke Kunshan University. It began hitting its stride in the last few years and could ultimately provide the same benefit.

A less ambitious alternative is to optimize your video to traverse the firewalls and the bottlenecks. The feedback I’ve gotten over the past year says that maintaining a rung on your encoding ladder with a bitrate of, at most, 550Kbps total will usually allow video to be smoothly play­able at normal speed during off-peak hours; students overseas will struggle to watch video at faster playback rates since the data rate increases apace the speed. My lowest rung is 148K, which will allow students to play video smoothly at 1.5x speed even during peak usage times. Students have also reported that their internet speeds are much worse during peak workday hours overseas, although I wasn’t able to determine whether that was a bottleneck problem at ingress, last mile, or both. And finally, overseas VPN usage dramatically reduces measured throughput. VPNs are arguably illegal in China, so I would advise schools to absolutely avoid anything on the internet that’s blocked by the Great Firewall.

An attractive hybrid approach would be to use peer-to-peer (P2P) streaming, in which students would share among themselves video data that has traversed the firewall instead of fetching it through the firewall each time. Since educational video tends to be viewed in batches as cohorts of students go through the course, it lends itself very well to this model, as does China’s network architecture, in which P2P is a proven technology of platforms like PPTV and PPS.

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