When are Mobile Networks Functionally Equivalent to Fixed Networks?

At what point, and under what circumstances, are mobile networks, satellite or fixed wireless networks “functionally equivalent” to fixed networks?

That is not to compare raw speeds or bandwidth, but the ability to support similar end user experience.

It generally is true that fixed networks, especially those using optical fiber physical media (fiber to premises) or a hybrid approach (hybrid fiber coax or fiber to the neighborhood), offer more end user bandwidth than a mobile network.

A recent study sponsored by Ofcom, the U.K. communications regulator, for example, found that beyond 10 Mbps, local access speed is not the experience bottleneck.

The study found that “access speed” matters substantially at downstream speeds of 5 Mbps and lower. In other words, “speed matters” for user experience when overall access speed is low.

For downstream speeds of 5 Mbps to 10 Mbps, the downstream speed matters somewhat.

But at 10 Mbps or faster speeds, the actual downstream speed has negligible to no impact on

end user experience.

Since the average downstream speed in the United Kingdom now is about 23 Mbps, higher speeds--whatever the perceived marketing advantages--have scant impact on end user application experience. Some 85 percent of U.K. fixed network Internet access customers have service at 10 Mbps or faster.

Investing too much in high speed access is, as a business issue, as bad as investing too little, one might argue. One might also argue that, functionally, end user bandwidth beyond 10 Mbps simply does not matter, at the moment.

The caveat is that the number of simultaneously users matters. Two users concurrently using a single connection might require 20 Mbps to experience maximum quality of experience.

As part of an effort to preserve high speed access funds for fixed networks, as opposed to allowing mobile networks to receive funds, NTCA: The Rural Broadband Association sponsored a study that argues mobile networks do not compare to fixed networks, where it comes to bandwidth.

That arguably is true, though the study also uses a perhaps-slanted approach to analyzing mobile bandwidth, assuming two bits per hertz as the measure of mobile network coding efficiency, even if Long Term Evolution achieves double that degree of efficiency.

Beyond that, coming fifth generation networks might be capable of gigabit per second speeds in a great number of situations, functionally erasing any difference between fixed and mobile networks.  

No matter what the U.S. Federal Communications Commission or any other body mandates, user experience beyond 10 Mbps (or 10 Mbps per concurrent user, if you like) renders no perceivable value.

That applies to the new 25 Mbps high speed access standard recently set by the U.S. Federal Communications Commission. Whatever else one might argue, moving the goalposts does not change end user experience, even if it does affect the flow of universal service funds and investment requirements.

The point is that, at 10 Mbps per concurrent user, all access networks are functionally equivalent, in terms of bandwidth, if not always equivalent in terms of latency. Of course, if fifth generation (5G) networks manage to achieve current design goals, latency will not be an issue for 5G mobile networks.

The goal is latency of one millisecond and bandwidths between 10 Gbps and 50 Gbps.

Comparing networks in terms of raw performance is one thing, though. Comparing networks in terms of end user quality of experience is something quite different.