Operators facing increased 3G traffic (thanks to smartphones and the applications explosion) are increasingly considering offloading traffic to Wi-Fi or femtocell networks as a solution to the capacity crunch. There are a few reasons that makes sense.
Data made its foray into cellular networks around 2002 with 2.5G networks. The initial uptake of these GPRS and CDMA-1xRTT networks was slow. There was little that could be done with clunky voice-centric handsets and lack of data services. The BlackBerry changed that and began to whet the consumer’s appetite for a service beyond voice. The iPhone continued to expose consumers to mobile Internet and rich data services such as mobile video. Operators have been compelled to scramble to expand 3G networks to support this phenomenon. Yet this is only the start of the data deluge where the infrastructure is finding it hard to keep up.
Solving this conundrum requires an understanding of certain mobile data realities. For one, the 3G infrastructure required to deliver data services to smartphones is creaking at two main points: radio and backhaul. Wireless spectrum is a limited resource. Radio technology continues to improve the efficiency of transmission and reception, but there are limits to how many bits can be packed into a radio stream.
Further, network congestion is caused disproportionately by users. AT&T for instance has acknowledged a 5000 percent growth in data in the last three years. More importantly, the top 3 percent of smartphone users are consuming 40 percent of network capacity. They are consuming 13 times the data of an average smartphone user.
There are several ways operators can address the challenge. Increasing capacity in underserved areas can be done by building new cell-sites. Addressing traffic demands can be offset by technology upgrade such as HSPA+. However these options come at a high cost to the operator.
Augmenting and improving backhaul capacity can also mitigate this problem. Additional T1/OC3 lines can be linked to cell-sites to increase data capacity. The flow of traffic on the pipe can also be controlled using packet inspection and service level policy. In addition, caching the overall content can also help to smooth the flow of traffic.
Overlay networks offer an orthogonal solution. These exploit an alternate path to deliver data wirelessly to the user at cost-effective price points. Overlay networks exploit the service provider’s licensed spectrum with a femtocell solution or a ubiquitously available unlicensed spectrum for Wi-Fi networks. Both strategies extend the operator’s network footprint.
The Case for Offload
Many contend that scaling network capacity is only masking the problem. While providing a broader delivery pipe, most users realize a fractional benefit as a few consumers will continue to hog the increased bandwidth. Optimization is a promising solution as it helps in flow-control, but it is costly and raises privacy issues.
