A few weeks ago, I received an email from my mobile network operator about a WiFi hotspot service it is launching in several cities
. The service promises users free access to thousands of hotspots to surf the Internet without using up their data plans.
In a typical European or US city in 2012, there were more than 50,000 cellular data users per square kilometer, generating 300 GB of data daily. These numbers will increase tenfold by 2015.
Now carriers, faced with the challenge of providing more wireless infrastructure for hungry users, are turning to their residential customers for help -- but not openly. Some carriers are converting their residential customers' WiFi connections into wireless hotspots to supplement their 3G and 4G networks, without informing them.
The strategy, called WiFi offloading, is incorporated into the new ADSL and fiber contracts. It allows the operator to create a different access point in every router for its mobile customers.
The advantage for the ISPs is huge. They get to offload traffic from their saturated 3G and LTE networks without incurring additional cost, since their DSL, cable, and fiber customers are providing the infrastructure. For mobile customers, the switch to WiFi is completely unnoticeable -- the terminal connects to WiFi automatically when passing by a node in the network without interrupting service -- and many operators are offering additional data allowance of 5 GB and 10 GB on WiFi offload.
I just found the clause about WiFi offloading in our Barcelona fiber contract (clause No. 29). Though our ISP is not offering it yet, it is enabled by default, and up to 10% of our bandwidth can be used. According to the contract, we can turn it off by calling customer service or through the router configuration. (I haven't found the option yet.)
One of the issues is that the WiFi 2.4 GHz spectrum is completely saturated. It is impossible to find a clear channel in any residential area. If ISPs are turning on additional access points in our routers, they are adding more noise to the already crowded spectrum. If I connect to the router directly by ethernet cable, I can enjoy the 50 Mbit/s of my fiber connection, but on WiFi, the speed drops to 25-30 Mbit/s, depending on where I work in the house. When 802.11ac becomes widely available on the 5 GHz band, that problem will go away for a while, but I doubt ISPs will be changing the routers to the new standard anytime soon.
Another issue is power consumption. Most WiFi routers already use low transmitting power, but the additional access points will increase the power usage of the devices.
But the most disturbing part is privacy. WiFi offloading is taking advantage of user isolation, so cellular users won't have access to other devices on the network. But that won't stop hackers from circumventing the isolation block and potentially tapping residential networks.
That's really serious when you consider WiFi connected devices such as appliances, thermostats, and other sensors in our homes. Imagine someone accessing your phone lines (most are IP based now) or switching on your heating during the summer.
Obviously, this works only if you are using the ISP-provided WiFi equipment. Otherwise, the provider has no way to enable the service unless the user grants remote access.
It is clear that WiFi offloading is here to stay, and it will probably be part of the upcoming 5G standard. But broadband customers should be informed (without having to read the small print of every contract) of the possibility that their ISP is turning on that service on their devices. My hope is that the service will be opt-in and will offer something in exchange, such as free unlimited access to the hotspot network, but it looks like each ISP will be deciding for itself how to offer the service.
If you are not happy with the prospect of opening your broadband connection to others, I suggest you call your ISP and politely tell it to shut WiFi offloading off.