Previous calls for enhanced coverage have mostly focussed on cellular, and previous efforts to provide widespread Wi-Fi “municipal” coverage have generally been seen as a failure. The steps set out in the previous section would move Wi-Fi back centre-stage in the world of communications. Is this plausible, and have lessons been learnt from previous attempts to deploy widespread Wi-Fi?
The 5G Myth
Selected by Author
Dr. William Webb
This book critically examines the myriad proposals for the next generation of mobile communications – 5G – and shows that there are many flaws in what is proposed. Indeed, it concludes that the vision of 5G as currently laid out is so badly flawed it is highly unlikely to be implemented. The book does so in a number of stages.
It is worth recalling that we already live in a Wi-Fi-first world. Well over 50% of the traffic from our mobile phones flows over Wi-Fi and typically 100% of the data from tablets and laptops. Wi-Fi carries at least an order of magnitude more data than cellular, perhaps even two orders of magnitude. We typically own only one cellular-connected device but often five or more Wi-Fi connected devices. There are probably around 20 million Wi-Fi access points in a country like the UK, but only around 60,000 cellular base stations. A hotel or office without Wi-Fi would be seen as unacceptable, one without cellular coverage merely irritating. This is not to underplay cellular which has a critical role in providing coverage while on the move and will remain an essential part of our communications infrastructure for the foreseeable future.
There are good reasons why Wi-Fi is preferred in most cases. Cellular is expensive to provide and has inherently limited capacity. Wi-Fi is almost free to provide and we are still a long way from reaching the capacity of current systems. This is not because of technology or spectrum – both use near-identical technologies (OFDM) and have near-identical amounts of spectrum available to them (around 500MHz in total). The difference comes from the deployment model. Deploying coverage “inside – out” is much more efficient than “outside -in”. With most data usage taking place inside buildings and with the outer walls of the buildings forming a partial barrier to radio waves, then delivering the radio signal from inside the building ensures users have a strong signal and takes advantage of the isolation provided by the walls to reduce interference to other users. Conversely, cellular systems have to aim to blast through the outside walls, delivering poor signals inside which reduce overall cell capacity, and result in interference between outdoor cells. In principle, cellular could deploy indoors too – and many attempts to do so using “femtocells” and similar have been tried. But the scale of the deployment challenge is beyond a single company and only achieved with Wi-Fi through the actions of millions of users deploying their own access points. Now that we have Wi-Fi widely deployed the rationale for also deploying cellular indoors is reduced and a self-fulfilling movement towards Wi-Fi only-devices has happened knowing that Wi-Fi connectivity is likely.
This is not to attempt to replace cellular. Wi-Fi can never provide connectivity in rural areas, along most roads and for most people when moving. Cellular is an essential component of our complete communications infrastructure, just not the best way to deliver the final elements needed for ubiquity in most cases.
The remainder of this section considers the changes and additions that might be needed to Wi-Fi in order for it to properly fulfil its central role.