By Greg Chiasson, PRTM Management Consultants

Overcoming the backhaul bottleneck is a key challenge in successfully deploying WiMAX, LTE, and other next-generation communication systems. Backhaul is a critical element of 4G business models, affecting capital investment, operational expense, time to market, and the customer experience.

While backhaul-related technical and deployment issues abound, making the business model work in the face of backhaul costs is even more daunting. Even today, backhaul is one of the largest operational expenses a carrier faces, comprising up to 40 percent of recurring network expenses. 4G systems, which demand substantially greater backhaul capacity, have the potential to significantly magnify these cost challenges.

AT&T may be trying to block the merger of Sprint Nextel's and Clearwire's WiMAX activities, but it is also proceeding with its own, more limited, plans for the technology. The telco has been trialling WiMAX-class technologies in rural areas for a few years and now its CTO John Donovan says the system is "at the top of the list" as an alternative to copper.

Donovan said, in an interview with newspaper USA Today that the cost of copper roll-out was making it prohibitively expensive to build DSL for rural communities. This is the usual dilemma that has left the US' rural reaches sadly underserved by broadband and 3G - high cost of deployment, coupled with sparse and often low income populations, and falling broadband tariffs. This ROI-challenging combination could be addressed by broadband wireless, and specifically the standards-based economics of WiMAX, believes Donovan, echoing the view of WiMAX that has driven most of the world's actual deployments, away from the headlines about mobile broadband and 4G - that it is a natural leader for wireless DSL and fixed/nomadic access for underserved areas, and this market will be far easier to dominate than mobile applications.