"If customers don't notice the difference, then they won't want pay for more" explained Gavin Young MIEEE FIET, Head of Fixed Access, Centre of Excellence at Vodafone Group Technology at the 'Quality Attenuation and its Impact on Broadband Service Assurance' webinar organised by the IET Anglian Coastal Local Network hosted by Kevin Foster.

Gavin, started at the basics, so as packets go through hops, they either get delayed, or get dropped, ideally, we want zero delay and zero loss, however this never happens, and the difference is known as the 'delta' which is degradation from a perfect state. The delta is dependent on variables such as Wi-Fi issues or rerouting or can now even be serverless apps moving around dynamically.

For years broadband has been focused on speed. The more speed meant better application speeds , but now we are at a point where we are reaching diminishing performance. If we get quality right, then we get better utility prospects. He explained that not all bandwidth is created equally, so when it comes to buffering your streaming service, 50 Mbit on an empty network is different to a loaded network, packet serialisation is therefore different.

Giving more insights into Quality-of-Service models, he explained in the early days of broadband, it was acceptable to measure a link using its bandwidth range, however, now bandwidth is not fungible. Packets move differently - simply because the physical layer itself is adapting, including how we might use the TCP protocol, which means we need to look more closely at the quality-models of a network, in addition to the bandwidth model.

The familiar consumer bandwidth-model of 'more bandwidth means better speeds', or higher bandwidth rates are better,  is different to a vendors chosen quality-model, which aligns itself to the consumer thought of 'zero packet loss - thus zero defects - thus zero delay'. He explained that the quality-model is a better measure of how close you are to zero than infinity.

Will my entertainment-streams or business meetings stop buffering finally?

This is where the quality-model can add value, he explained how Vodafone have been researching the limitations of the bandwidth model and now how the quality model can enhance network performance. Specifically, by analysing the round-trip-time (RRT) into 3 latency components;


  • Serialisation Delay - Factors that affect interface speeds.

  • Geographic 'Given' Delay - Physical layer transmission.

  • Variable Delay - Network load schemes.

You can now see that by analysing any of these 3 factors in a link, the network service can be enhanced to ensure an increase in performance, whether the need to better identify hotspots that need additional routers, how CDN's can get closer to the customer, or to even get answers to why we are seeing packet buffering - with this level of analysis, the quality model lets us finally understand what factors effect the upstream and downstream link, thus giving the types of insights that can benefit the consumers.

This of course needs testing, so he explained how Vodafone uses packet simulators to test for hops, delays, quality of attenuation and scheduling, however, the true constant remains, at the packet layer, the longer the path the longer the latency.

A good webinar that demonstrated how we got to 'unlimited' bandwidth, and now how we can expect to enhance network performance, such as the ability to predict the delta inefficiencies and respond to them using A.I to achieve the perfect stream!

Robert Heaton