Recently, there has been a lot of discussion regarding iPhones straining AT&T Inc.’s wireless network, but that’s just the tip of the iceberg. While the iPhone is a powerful little device, in the big picture it shows only what can happen to 3G mobile broadband networks when just a fraction of Internet traffic migrates over to them.
Consider Internet-ready netbooks, data cards and wireless dongles: The wireless threat is vastly multiplied with these offerings. These devices literally have the potential to shift entire broadband Internet traffic consumption patterns to mobile networks. From large peer-to-peer (P2P) file transfers to Internet video to streaming audio, all are potential traffic types that can be migrated to mobile broadband networks quickly and easily – with devastating effects if not managed appropriately by the operator.
The average iPhone user downloads and checks e-mail – however, most of these downloads are done, by default, without big attachments. Similarly, while subscribers may occasionally use iPhones to view YouTube videos, the total volume of such wireless traffic pales in comparison to overall fixed line Internet video traffic.
It’s a fact: Wireless networks are inherently spectrum limited. A close look at the 3G channel structure shows that for data traffic, each cell site has a “shared” high-speed channel for downlink and uplink bandwidth – called HSDPA and HSUPA (for High Speed Packet Downlink and Uplink Access). This big fat pipe in a cell site is shared by all of the users in that cell.
The principle of a shared channel works well when data traffic is bursty in nature – for example, for a Web page download, an e-mail transmission or a database update – when each user in the cell uses the limited bandwidth for a very short duration.
However, as Internet traffic has changed over time – primarily because of video and P2P traffic – a single user can consume a significant (and disproportionate) amount of shared channel bandwidth for a sustained duration. This completely breaks the shared channel paradigm and leads to the situation that AT&T is lamenting.
The solution is cell-splitting and adding more cell sites to create more aggregate bandwidth. This is easier said than done, though, given the fact that wireless data pricing plans are still mostly flat rate rather than metered. In fact, the current decoupling between skyrocketing traffic growth and horizontal revenue streams is the single biggest challenge that wireless network operators face today.
