It used to be the case that around 80% of smartphone data was delivered over Wi-Fi and 20% by cellular. Fast, high capacity LTE together with competitive pricing is shifting that mix – in some cases quite dramatically. Recent statistics support this trend, both in developed and developing markets.
What is Wi-Fi?
Wi-Fi technology, standardised through the IEEE 802.11 series of standards, has become widespread, low cost and easily accesible. Equipment certification and interoperability have been ensured by the Wi-Fi Alliance, a trade alliance which promotes the technology and interworking. The Wireless Broadband Alliance have developed operating procedures and processes to enable roaming between public Wi-Fi networks, including security based on cellular network SIM cards.
The technology operates on unlicenced frequencies, at 2.4GHz and 5GHz. This is shared with many other users and devices, from baby alarms to security cameras, but the low RF power tends to limit the range. This makes it ideal in many residential settings, but can cause interference problems in dense urban areas, such as tower blocks and shopping malls. Battery power drain when using Wi-Fi has also been a concern.
Later versions of the Wi-Fi standard promise ever faster speeds, better tolerance of interference conditions and security. 802.11ad (also known as Wi-Gig) offers multi-Gigabit traffic rates over short distance in the 60GHz band. 802.11ac promises 500Mbit/s or more in the 5GHz band.
Wi-Fi now seen as an extra resource, not a threat
Wi-Fi was first seen by mobile operators as a threat, but it was quickly realised that the technology could be used to relieve capacity demands by offloading traffic when at home, in the office or even some public locations. Smartphones were mandated to include the technology, and few (if any) are available today without it. Not all smartphones have the latest standards though, and there is a large installed base with older versions.
Some operators have deployed huge numbers - hundreds of thousands - of public access Wi-Fi hotspots in order to relieve capacity on their cellular networks. Users actively seek out these hotspots, partly because they can find faster data rates than on 3G and partly because they may be cheaper (not counting towards their cellular data cap). US operators such as Verizon and AT&T have reported that as much as 50% of user traffic is carried via their public Wi-Fi network. In some cases, much more additional data traffic may be handled outside the operators network on residential or office Wi-Fi. China Mobile already has more than 1 million and promises to deploy as many as 6 million across the country by 2015.
However, there can be problems if too many Wi-Fi hotspots are co-located. Popular exhibition venues are a common example, but Japanese and Korean operators have found capacity saturated in urban areas and now seek to invest in LTE in licenced spectrum to increase system throughput and improve quality of service. Qualcomm published a report in 2010 on this topic, comparing Wi-Fi with LTE small cells, which we reviewed here.
Implications for small cells
Wi-Fi has now become an optional feature for many metrocells, and can be deployed at the same time. Developments by the Wi-Fi Broadband Alliance should make it easier to integrate Wi-Fi as part of the cellular operator's service, sharing the same SIM card authentication and billing/roaming arrangements.We explain how Wi-Fi and Cellular networks will become more integrated, with some help from senior Cisco architects. We also reviewed a white paper published by the Small Cell Forum, which clearly segments the different types of wireless traffic that are suitable for each case.
Some believe that in the long term small cells will select which of 3G, LTE and/or Wi-Fi radio technologies to use in real time, deciding based on device capability, traffic demand, traffic type and tariff plan. This would make best use of all available spectrum and deliver the best performance. Others believe that service using controlled spectrum will usually be better, and that Wi-Fi is a useful, best effort service for lower priority or lower cost applications.
Further Reading includes:
- More about our view on the longer term position of Wi-Fi.
- Our explanation of how Wi-Fi and Cellular networks will become more integrated
- Slideshare presentation explaining HotSpot 2.0, Passpoint and Carrier Wi-Fi evolution
- Our review of a Wi-Fi/Small Cell white paper published by the Small Cell Forum
- Our take on Qualcomm's comparison of Wi-Fi and LTE
Several recent announcements and developments for public Wi-Fi service highlight both success and setbacks. We recap and assess the situation. Why are some succeeding while others fail and how will the forthcoming LAA and MulteFire technologies displace or complement Wi-Fi in the longer term?
You may be forgiven for thinking that smartphone data flow is the same regardless of whether it’s sent over Wi-Fi or cellular networks. It isn’t. Smartphones actively discriminate between the two, and that leads to a distortion of traffic quantity and uplink/downlink ratio. We consider the implications.
Amenity Wi-Fi has become an important service for public facing businesses to offer. Hotels, retail stores, even restaurants visibly promote its availability. But there is a plethora of different services on offer, some making for an unpleasant experience. Should service quality be clearly labelled, and will a seamless service prove more popular?
Wi-Fi Calling provides seamless access to mobile voice and is now incorporated into several popular smartphones. The intention is that users should not even be aware they are using it. But the chance of a dropped or poor quality call is higher and is holding back wider deployment. We consider the issues and look at some alternative architectures that propose a way around the technical problems.