The day Apple rolled out the iOS7 operating system could have been disastrous for wireless networks. It was downloaded more than 200 million times in the first 72 hours and each of those downloads was more than 700 MB.
Mobile carriers potentially needed to manage a total of more than 140 exabytes of unanticipated data. The downloading process had to take place over Wi-Fi, a savior at times like these when a sudden, crushing demand can test the true resilience of any wireless network.
Wi-Fi is a potentially “win-win” technology for consumers and carriers alike -- the ability to offload to Wi-Fi alleviates congestion on wireless networks, provides a seamless uninterrupted connection (at least that’s the intention) and time spent on Wi-Fi does not count against the user’s data package.
Furthermore, it’s a cost-effective option for mobile carriers. Networks can set up a Wi-Fi node to handle part of the load for a fraction of the price of adding a macrocell to handle a rapidly growing geographical area or heavily attended localized event.
Let’s consider some of the challenges and ways carriers can ensure they deliver against the promise.
Firstly, it’s important to understand that devices will usually be preconfigured to accept being offloaded to carrier Wi-Fi automatically, without the user needing to take any action. The phone is shipped with Wi-Fi “on” as default and there are no passwords or authentication details required. The decision to move a connection to Wi-Fi will normally be based on geographical location.
So, when the device enters that location, the core network will automatically switch the user to an available Wi-Fi router, without interruption in connectivity. If users notice any change it will just be their signal indicator moving to the Wi-Fi symbol while receiving a seamless experience.
Unfortunately, reality does not always correspond to the intention. Since Wi-Fi spectrum is not licensed, unlikely to be owned by the carrier, and more likely to be part of a patchwork quilt of different providers including hotels, shopping centers and so on, quality of service (QoS) after handover can be extremely unpredictable.