Christopher Howson

Distributed & adaptive HTTP streaming

Adaptive streaming with HTTP has become popular in recent years, enabling continuous delivery of live and VOD content without the need for guaranteed bandwidth. It remains however challenging to maintain a smooth quality of experience under tough network conditions especially for bandwidth eater content like High Definition or 3D. In this paper we show that it is possible to both greatly improve the average quality and attenuate the quality variations for a better user experience by leveraging multipath communication requiring no extra bandwidth. We exploit concurrently multiple paths using a CDN compliant distributed streaming infrastructure and standard HTTP range requests and present the results of several network configurations.

Fast second screen TV synchronization combining audio fingerprint technique and generalized cross correlation

For the implementation of emerging second screen TV applications, there is a need for a technique to assure fast and accurate synchronization of media components streamed over different networks to different rendering devices. One approach of great value is to exploit the unmodified audio stream of the original media, and compare it to a reference version. We consider two major approaches for this purpose, namely finger-printing techniques and generalized cross correlation, where the former can greatly reduce computational cost and the latter can offer sample-accurate synchronization. We propose an approach combining these two techniques where coarse frame-accurate synchronization positions are first found by fingerprint matching, then a possible accurate synchronization position is verified by generalized cross correlation with phase transform (GCC-PHAT). Experimental results in a real-world setting confirm the accuracy and rapidity of the proposed approach.

Introducing innovative services with a dense broadcast network

We introduce a novel broadcast network architecture, where macro and micro Base Stations (BS) transmit partially the same signal in a SFN manner. Leveraging this architecture we propose to operate the medium as a pure IP multicast bearer coupled with a feedback channel for scheduling and optimizing the bandwidth usage. The extra bandwidth can be managed locally with a fine grain thanks to the dense BS deployment. Such a system drastically improves the coverage area, including indoor, while reducing power consumption, using low power transmitters and well targeted transmissions. It also copes with the ramping up of “green” requirements. The single frequency operation also leads to a highly bandwidth efficient system, suitable for exploitation of the digital dividend in the UHF band for instance. Finally, this system can introduce some innovative services, potentially managed by new players so that the overall revenues pay back the dense radio architecture.