December 2018

A number of mobile operators across Europe offer a fixed wireless access (FWA) service where they also market their network as a replacement for home broadband. Quite what form this takes varies, from using the phone as a Wi-Fi hotspot to a dedicated cellular modem with either internal or external antenna. This brings increased revenue to the operator as well as more broadband competition for the country, but does it come at a cost?

On the face of it, FWA would appear to be a challenge for mobile network operators (MNOs). A typical mobile user across Europe consumes around 2GB of data per month, while a typical house consumes more like 200GB per month. A house contains more than one person (in the UK on average it’s 2.3) so the personal consumption at home is around 86GB per month - more than 40 times the mobile consumption. Can mobile networks soak this load up without impacting their service?

To assess this we looked at the difference in the average download speed between midday and 9pm across a number of operators, some of who provide FWA and some of who do not. (Note that there is nothing to stop a subscriber using a mobile service for FWA even if the MNO does not explicitly offer this, so we would anticipate some FWA even for those MNOs that do not offer it.) We would expect that those operators with a significant FWA offering would see heavier loading at 9PM than those without as subscribers return home and start streaming video at high resolution onto large screens.

The results are shown in the table below:

The results are quite striking. For the operators that do not offer FWA, average download speeds at 9PM are higher than those at midday. For those that do offer FWA the inverse is true. Taking Plus in Poland, for example, download speeds fall to 8 Mbps in the evening - fine for mobile usage, but rather on the low side for good home broadband.

The fall - of about 20% compared to the non FWA operators - is significant. FWA is likely to be used in cells that are not congested for mobile use, both because the mobile traffic load is less in the evening and also because residential usage tends to be away from dense urban areas where congestion is higher. So as FWA is initially deployed, usage would likely not have an impact on throughput speeds at all as it consumed the spare capacity in the cell. However, once the capacity is used then average throughput speed starts to fall. At this point, the fall becomes broadly linear - a 10% increase in overall activity would result in a 10% drop in average data speed, all else being equal. With home broadband consuming 40x the mobile usage, less than a 1% growth in FWA might trigger a 10% reduction in throughput speeds at this point.

What can this tell us?

1. We can deduce which MNOs have a significant percentage of subscribers using their service for home broadband. Unsurprisingly, this correlates very strongly with the MNOs with relatively high data volumes, such as Finland, suggesting that high volumes are less driven by early adoption of mobile data usage and more by higher use of home broadband.

2. It looks like FWA cannot grow substantially, at least not on 4G. As data volumes to the home rise ever-higher and services like Netflix become more important, the ability of mobile to deliver the necessary data rates will decline, potentially to the point that the service for all subscribers is compromised.

That begs the question as to whether 5G can change the dynamics. 5G will add significant capacity to a network, but the frequencies used may not penetrate buildings well, requiring an external antenna.  And the additional capacity may be quickly consumed as home broadband usage grows. With crowdsourcing we will be able to quickly assess what is happening.

Written by Professor William Webb