Network engineers always have had to design for cost and efficiency, as well as to support expected traffic demand. That is why sharing of network resources is so important: it reduces capital investment.

But it is one thing to dimension a network for symmetrical apps. It is quite another matter to design a network supporting mostly asymmetrical traffic. That is something broadcast TV and radio engineers understand well.

One reason cable TV networks used asymmetrical frequency plans (much more bandwidth downstream, compared to upstream) is that the expected apps were “broadcast” (multicast in IP parlance).

As more content consumption moves to mobile networks, traffic patterns are changing.

Though mobile networks once were designed for symmetrical traffic, Internet traffic now drives bandwidth demand on mobile networks, and that traffic is highly asymmetrical, one reason access to Wi-Fi and other non-traditional networks has become so important.

What to do about that situation is the issue

Though social media video uploads could make a difference in some cases (such as user behavior at large entertainment events, where people are uploading videos, virtually all studies of “normal” traffic show a skew of traffic in the downstream direction, ranging from 3:1 to 10:1, downstream to upstream.

Telefónica O2’s customers, as an example, are using 60 percent more data than they were 12
months ago, and 600 percent more than at the end of 2010, according to Real Wireless.

The uplink:downlink ratio, on a mobile network supporting 3G or 4G, is now about 1:7, and much of the downstream traffic is bandwidth-intensive video.

So will most mobile networks be refashioned for asymmetrical traffic? To a point, perhaps, though mostly in the form of supplying more overall bandwidth at heavy traffic locations, using small cells, carrier Wi-Fi or Wi-Fi offload.

That is why spectrum sharing, and the move towards dynamic spectrum allocation, are important. They will allow offloading of asymmetrical mobile data demand.
Even if mobile networks fundamentally remain designed for symmetrical bandwidth upstream and downstream, future requirements for support of asymmetrical traffic will be accommodated by increasing the total amount of available bandwidth, offloaded from the core mobile network.