Tuesday, November 20, 2007
Ericsson Unveils a Bold New Approach to the Cell Tower Issue
A major problem impeding the rollout of new wireless services is the compatibility of the antenna towers/infrastructure required and the local environment. This affects mobile operators, fixed wireless access providers, and even private land mobile (Part 90) operators who want to improve their efficiency by switching to a cellular structure. All of these systems need antenna sites in suburbia* roughly every mile or so. The basic endoskeleton system used today, a tower with multiple antennas bolted to multiple platforms at different heights is visually objectionable to a large sector of the public.
The wireless industry has been amazingly insensitive to this issue: building more and more visually discordant structures while they press - with limited success - legal approaches like local preemption. Chairman Ferris' mentor "Tip" O'Neill famously said "all politics is local" - a truism that in general dooms the preemption approach to tower siting.
Traditional endoskeleton antenna systems: No wonder the neighbors don't like them!
How many antennas are needed on each tower? FCC CMRS competition report says that 51% of US population in 2006 lived in counties with 5 or more CMRS carriers.
These need 5 or more antenna systems. And this is before the 700 MHz auctions and AWS auctions are finished! The BRS build out and other point-to-multipoint systems at higher frequencies will also need multiple antenna systems in suburbia. Finally, public safety agencies and other large Part 90 operators may well go to cellular architectures creating more antenna systems needed in a given area. I estimate that in a given area there will be a long term need for more than 12 mobile systems and 6 point-to-multipoint systems. That's a lot of antennas on a grid of 1 mile or less in suburbia if the traditional endoskeleton technology is used.
Ericsson's Tower Tube takes basically an exoskeleton approach, using a smooth exterior structure, in their case an advanced cement with fiber reinforcement, and antenna placement inside the structure so individual antenna elements are not visible. This type of approach could in general accommodate a large number of antennas and still keep a smooth, hopefully attractive design. As an added bonus, the Ericsson design keeps the equipment inside the tower, eliminating the usual security fence. However, a downside of the narrow diameter of this particular structure implementation is the limited horizontal width possible for each antenna with then limits sectorization of each tower. A larger diameter top, as on some water towers, would lessen this problem.
All sorts of variations on exoskeletons are possible besides the Ericsson one, the key issue is a nonconducting strong exterior. Other approaches with closely spaced flag pole-like structures are possible.
So my congratulation to Ericsson for "thinking outside the bun" and possibly convincing industry that new technology and improved design is a better approach than confrontation with local officials on preemption issues.
* While these wireless systems also need sites in urbanized areas and rural areas, the suburban problem is the most complex one. Urban areas generally have buildings that can be used to mount antennas with little visual impact. Rural areas generally have sparse population so antennas can be sited away from residences. While camouflaged antennas like fake trees have been used in limited instances, they are very expensive, not that convincing, and not readily adaptable to mounting multiple antennas