High Quality Web and Video

As webpages become more sophisticated, and video becomes higher definition, the volume of digital content transferred over the Internet is increasing. This has resulted in network congestion and problems such as increased latency to display webpages and sudden drops in communication quality such as video playback stopping in the middle of a video.

To address these issues, we are researching technologies that enable comfortable use of network services such as web and video services, including the following themes.

Cache Control Based on Correlation among Web Objects

In recent years, Web pages have become richer and more complex, and Web response times have increased. To reduce web response times, HTTP/2 was approved as a specification by the IETF in 2015, and HTTP/3 was also approved in 2020.

Although HTTP/2 and HTTP/3 reduce latency by fetching multiple objects in parallel over a single TCP session, parallel delivery is only possible for a set of web objects retrieved from the same delivery server. Therefore, when a small number of objects are retrieved from many delivery servers in a distributed manner, the effectiveness of HTTP/2 and HTTP/3 parallel delivery is limited.

To this end, our laboratory is working on cache control techniques that prioritize web objects to be left in the cache based on correlation between web objects.

Caching Techniques at Mobile Terminals Using Deep Learning

More and more people are watching videos on mobile devices such as smartphones. However, due to the large size of video data, communication resources on mobile networks are expected to become scarce. Therefore, it is effective to utilize mobile terminals as caches to distribute content among mobile terminals. However, since the memory size of mobile devices is small, it is necessary to appropriately select which content to store in mobile devices based on future demand for the contents.

To this end, we are working on cache technology that uses deep learning to predict highly popular content in future at destinations of mobile devices and selects content to be stored in the mobile device.

Similarity-based cache control for Mobile Crowd Photographing

The use of Mobile Crowd Photographing, in which photos taken with a smartphone are shared on a network and used as an image database, is expanding. Due to the large size of image data, it is effective to store and distribute the data in a cache on the network. However, duplicating similar image data in the cache reduces the effectiveness of the cache.

Therefore, this laboratory is working on a cache technology that prioritizes image data with low similarity to cached image data and leaves them in the cache.