Professor William Webb, Chief Technology Officer, OpenSignal
Mobile networks are incredible in their ability to allow us to connect with the world in many different ways as we go about our daily lives. Being able to video-call while commuting was science fiction until about a decade or two ago. However, it is equally important to accept that mobile connections are not perfect, and the more we rely on them, the more frustrated we become when they let us down.
It is tempting to believe that the solution in such a scenario is high speed. But high speed can help only up to a point. There are various other factors that need to align as well for ensuring a great mobile experience. The first of these is simple coverage. While operators may improve speeds in city centres, if they fail to deliver reliable coverage elsewhere, this may mean dropped calls or erratic internet connectivity while on the go. Indeed, most of the reasons for poor performance are coverage related. Coverage is not always easy to fix and can be expensive for the operator. By identifying the coverage gaps that impact most users, data derived from on-device apps can ensure that operators utilise their spectrum in the way that has the greatest impact.
Another issue is the delay in getting data from the handset to the network and vice versa. This is called latency, which is broadly a measure of the time period between a request being sent somewhere, like to a Facebook server, and a response being received. Latency in mobile networks varies from around 50 metres to 500 metres per second. While half a second may not sound like much, a typical webpage will often contain 10 or more elements, each of which gets fetched separately and so the overall delay could add up to five seconds or more. In fact, for most applications, once the data rate reaches beyond around 4 Mbps, it is the latency that tends to restrict the download time rather than the speed. A network with high speed but poor latency would be like a highway with lots of traffic lights. Cars can get between the lights faster, but the journey takes just as long.
Finally, even if all of this works well on a network with a small number of users, as user numbers grow, 
so does the network congestion, limiting the performance for all. Operators can build networks with more capacity but this would be costly and in some cases, difficult. Just as roads have rush hours, so do networks; their performance during the early evening hours can often be much worse than at night. So, the overall picture is more complex than just the speed. It depends on where users travel, what applications they use, whether they have alternatives available, like Wi-Fi, and what time of the day they are trying to use the network. Users ideally need to know which networks provide them with the best overall experience for their particular circumstances and governments need to ensure that networks are optimised in order to provide the best overall experience to their citizens. It is tempting to focus on speed as a simple measure that all can understand but as speeds grow, other factors increasingly limit the experience and more nuanced measures are needed.
