Broadcast Wi-fi aims to provide delivery of content at events and venues to relatively large numbers of people providing a virtual giant screen. Use of custom wi-fi systems means that content can be sent to mobile devices without encroaching on the audience’s data plan. There are many hurdles to cross to make this happen and those are the subject of our research.
Project from - present
Why it matters
Streaming video to many devices uses a lot of bandwidth. One way of reducing the bandwidth used is to implement some-kind of broadcast like system. Luckily, in the IP (Internet Protocol) world there is such a system known as multicast, which is designed to be used with wired networks.
Most IP traffic is unicast; a message (packet) is sent to a particular destination and then then an acknowledgement or error message is sent back to the source. In the case of the latter the message is sent again. This repeats until the message is received or a timeout criterion is reached.
Multicast works differently. A broadcast message is sent to everyone on the network and there is no acknowledgement. This is ok on a wired network where packet loss is very low, but that is not the case for a wireless network, where packets are frequently lost.
What we're doing
Global Invacom has produced a prototype system, which takes a satellite feed, adds a FEC (forward error correction) based on Raptor Codes and outputs streams over wi-fi. The streams can be received with a custom app on mobile devices. The theory is that when the error correction implemented is greater than the error rate the stream can received without error.
We are testing the system in our screened room (a metal box with a door), so that we have an environment free radio wave interference. We can use those results to explore the system parameters and performance in a deterministic fashion enabling us to understand and optimise performance.
We are also conducting our first public trial at the Edinburgh Festival 2017 as part of BBC R&D’s yearly technology showcase. We can use this first trial to gather real world performance data. We’ve spent a lot of time with GI ironing out system bugs and tailoring it to our particular needs for EdFest and we’re very close to having a system that will work well enough for a first trial.
We hope to expand the system for larger audiences and we will continue to optimse the system further. We also would like to carry out more trials, so watch this space!
Successful large scale trials and competitively priced commercially available systems.
BBC R&D - All of our articles on 4G and 5G including:
This project is part of the Distribution Core Technologies section
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Project Engineer (Research)