LTE dreams of Spectrum, Wi-Fi dreams of Voice, while users dream of Good Service

Having seen explosive growth over the past five years, Wi-Fi has completely changed the way we communicate and consume data, and cemented itself firmly into our daily lives. Many users can’t wait to switch from mobile internet to Wi-Fi to save their precious monthly data allowance. What’s more, Wi-Fi is growing quickly in the carrier market, with spending rising at a fast pace. An IGR study released in October 2014, forecasted that $3.2 billion will be spent between 2013 and 2018 on the installation of North American carrier and cable-operator Wi-Fi hotspots.

So does this mean small cells should be worried? Have we been caught napping whilst Wi-Fi has run away with the ball?

Wi-Fi’s growth has so far been driven primarily by the simplicity of deployment and easy availability of spectrum. With the arrival of Hotspot 2.0, the well reported issues of Wi-Fi security and authentication are largely addressed.  Mobile subscriptions can be used to access carrier Wi-Fi as easily, as widely and as securely as regular cellular.

Does this mean Wi-Fi is levelling up to cellular, feature-by-feature, ready to replace it? Not completely. Other issues inherent to the Wi-Fi radio are emerging as the deployments scale upwards. We’re all familiar with the congestion that Wi-Fi suffers in busy locations, and now that carriers are promoting Voice-over-Wi-Fi (again), that congestion will only get worse, with each voice call taking 10% of the Wi-Fi channel all on its own.  Wi-Fi is certainly gaining extra capacity from so many new devices supporting the 5GHz band, but with data consumption still growing at close to 70% a year, it’s soon going to be used up.

As demand for spectrum begins to exceed supply, and as licensed LTE radio technology (as used by carriers) begins to exploit new and unlicensed spectrum using emerging  techniques (like LTE-U, LAA) the pendulum currently swinging so strongly in Wi-Fi’s direction will slow and then reverse.

In this fast moving field, both mobile and internet standards bodies are racing to solve the issues for mass, uncoordinated deployments of carrier grade radios to give the consumer and the enterprise the mobile broadband they demand. By solving the voice-quality problem, the small packet performance problem, the bigger cell coverage problem, the multi-cell interference problems, the QoS weaknesses and so on, will we end up with a single air interface that is the perfect combination of LTE and Wi-Fi?

History tells us this is pretty unlikely.  But by unpicking the issues layer by layer, we can see where the small cell – Wi-Fi debate may resolve. Not by a happy coexistence but by a Cold War-style stalemate. Neither side can afford to introduce the features required to swallow up the other, without making itself vulnerable to a counterattack.  Can LTE-U afford to implement listen-before-talk simply to access 5GHz unlicensed spectrum?  Can 802.11 afford to introduce a scheduled MAC to let it carry voice efficiently?

Eventually this standoff may become unstable, as network traffic continues to grow in the face of spectrum constraints. What we are seeing is now a race for dominance with 3GPP and IEEE 802 slugging it out to become the small cell technology of choice. Of course, in the end, carriers make a substantial amount of money from delivering reliable voice as well as data and they need to be in control of a solution that does both well.

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