Caught in the hetnet

John C. Tanner
20 Apr 2012
It's no secret that the future of mobile networks is small cells. As cellular networks evolve to LTE, traditional macro cellular architecture isn't going to cut it - not with mobile data growing at exponential rates and with more and more devices connecting to the network.
The pitch is simple: to get the most out of their spectrum capacity, cellcos will have to deploy base stations closer to users in a variety of coverage options - from metro cells and micro cells to pico cells and femto cells. And cellcos are already buying into that pitch. According to In-Stat, global shipments of small-cell gear will reach $14 billion in the next five years, with outdoor metro cells alone achieving a CAGR of 248% in that timeframe.
Interestingly, that small-cell future includes Wi-Fi as well. Once the scourge of mobile broadband, Wi-Fi has become an increasingly common offload strategy for cellcos looking to take advantage of both its unlicensed spectrum (i.e. free access capacity) and its relative ubiquity in mobile devices in order to lighten the load on their RANs. But the emergence of small cells doesn't mean Wi-Fi offload is a stopgap, says Selina Lo, president and CEO of Ruckus Wireless.
"It's not about whether operators should deploy Wi-Fi or cellular within smaller cells - they need to do both," she says. "By putting small cells closer to the subscriber, operators can lower the cost of transporting each bit while boosting wireless capacity. Users will access the network at much higher data rates and be able to get on and off the network more quickly - utilizing less network capacity from a spectrum and time perspective."
The result: the next-gen mobile broadband access network is going to be largely heterogeneous. And that's going to complicate things tremendously on a number of levels, from access and network management to backhaul and class-of-service (CoS) management.
Wi-Fi integration
By no coincidence, this year's Mobile World Congress served as a platform for mobile network suppliers to showcase various solutions to the heterogeneous-network (or "hetnet") problem.
To name three marquee examples:
  • Alcatel-Lucent showcased its lightRadio Wi-Fi solution, which builds on the compan's next-gen lightRadio architecture and promises cellcos a way to enable customers to "switch automatically from a cellular service to residential or public Wi-Fi networks and hotspots without having to login, worry about payments schemes, or even be aware of the shift."
  • Nokia Siemens Networks unveiled Flexi Zone - based on its next-gen Liquid Radio architecture - in which multiple, inter-connected low-power small cells (which can be HSPA, LTE and Wi-Fi) use a common pool of resources managed flexibly by a "zone controller". Result: local offloading of internet traffic based on coverage and capacity needs, "saving up to 80% of transport and mobile packet core costs".
  • Cisco announced two new enhancements to its mobile infrastructure portfolio: small-cell (i.e. Wi-Fi/femtocell) gateway functionality on its ASR5000 platform, and Wi-Fi access points for service providers compliant with the new Hotspot 2.0 specification established by the Wi-Fi Alliance (more on that later).

The common thread is Wi-Fi integration, which is arguably the top challenge cellcos face in the hetnet paradigm.

"The need for small cells as a capacity enhancement and data offload tool is well understood," said Peter Jarich, service director with Current Analysis, in a research note. "What is not as frequently discussed is the need for holistic small-cell solutions including licensed spectrum and Wi-Fi assets along with common transport and control backed by deployment and business consulting insights."


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