IBC2023 Tech Papers: Multicast-Assisted Unicast Delivery

Abstract

There is growing use of the Internet to deliver television services by unicast. Delivering an individual stream for each viewer causes very popular content to drive large peaks in network traffic, which drives the need for network upgrades just to support the peaks.

We describe Multicast-Assisted Unicast Delivery (MAUD), the innovative approach we have developed to use multicast to assist with the unicast delivery of content, allowing content preparation and client applications to remain unchanged while reducing the large peaks in network traffic.

We also describe the trial we have performed with the CDN operator Qwilt where a Raspberry Pi was deployed in the home network of about 90 BT trialists, some of whom used the BT Sport app to request live BT Sport content, while others ran a robot-client on the Raspberry Pi.

Integration with the CDN Operator was straightforward, and analysis of performance statistics showed that the system behaved as expected. We plan further work towards ultimately deploying MAUD as a network- optimisation, cost reduction, technology.

Introduction

The delivery of audio-visual content is moving from traditional broadcast networks, including satellite, cable and terrestrial networks, to IP networks, where unicast delivery is often used to deliver a single copy of a content item to a viewer’s device, even when many people are viewing the same content at the same time. This drives ever higher demand on broadband IP networks, and ever higher capital expenditure to increase network capacity. If IP multicast could be used to deliver content that is viewed by many viewers at the same time, then the demand on broadband IP networks could be reduced, which would lead to reduced or delayed capital expenditure on increased network capacity.

However, IP multicast is rarely used for any services other than delivery of a network operator’s on-net television channels to their own set-top boxes because multicast does not lend itself to open use on the Internet. Hence to bring the benefits of multicast to unicast streaming, a class of techniques known as Multicast Adaptive Bit Rate (m-ABR) has been studied and standardised, but to date not widely deployed.

We describe some characteristics of current approaches that may have affected the rate of deployment, and then describe the novel approach to m-ABR called Multicast-Assisted Unicast Delivery (MAUD) that we have designed to enable more widespread use. We then report the trial we have performed with the CDN operator Qwilt to validate the MAUD design.