Fixed Networks are for "Capacity," Mobile Networks are for "Coverage"

These days, in many markets, people using smart phones are on the fixed networks for Internet access, more than on the mobile network. 

In North America, as much as 82 percent of Internet traffic from smart phones occurs indoors, where users can take advantage of Wi-Fi, instead of the mobile network,

Analysys Mason

suggests.

In Western Europe, as much as 92 percent of Internet usage from smart phones occurs indoors.

So to a large extent, that means the fixed network provides “capacity,” while the mobile network provides “coverage,” a statement that describes the two ways a small cell can provide value for an urban mobile network as well.

For the most part, Wi-Fi offload happens mostly in the office and the home. Some small cells will include Wi-Fi access, but the volume of Internet activity still occurs indoors, not outdoors where small cells will reinforce the mobile macrocell network.

Some tier one carriers have moved to create their own networks of public Wi-Fi hotspots, and many can serve customers from owned fixed networks as well. That makes the fixed network and public Wi-Fi a direct part of the mobile network.

In other cases, carriers simply passively allow their devices to use non-affiliated Wi-Fi networks, as when a mobile service provider allows a user to roam onto a fixed network owned by another service provider. 

That is one more example of the loosely-coupled nature of the Internet ecosystem. A mobile provider can offload traffic to another carrier with which it has no formal business relationship.