A WBA report brings some interesting potential cost estimates to the surface when the technology is modeled out as a complement to cellular - and it plays with percentages of traffic transported by the different technologies in a heterogeneous network and how that might ripple through to the bottom line.

Overall of course, the higher the proportion of data traffic carried by NGH WiFi the lower the overall per-bit costs for the network. It claims that mobile operators can reduce their per-bit RAN costs by 18 per cent when they carry just 20 per cent of their traffic via NGH WiFi - which indicates that WiFi is about a fifth the cost of cellular.

The WBA report claims the combination of Wi-Fi and cellular small cells brings even greater costs savings - as little as 38 per cent the cost of a 3G macro network.

Wrapping all that together it's claimed the potential cost savings and subsequent operator enthusiasm for the WiFi hybrid approach might lead to NGH WiFi accounting for 9 per cent of global mobile traffic by 2018 and being worth around US$150 billion.

In addition, trials of NGH has driven some new operator-friendly features in the standard claims the WBA - in particular secure authentication and automatic service discovery and selection. Soon NGH will support online sign-up and policy support as well.