WiMax Operator's Manual

86 CHAPTER 4 ■ SETTING UP PHYSICAL INFRASTRUCTURE
with the middle man, so to speak, or else reducing the middle man to a role of simply
negotiating and maintaining a link with an Internet Point of Presence. Mesh equipment,
inasmuch as it is nonhierarchical and self-organizing, inherently favors ad hoc, cooperative
associations of nodes, and some of the vendors have acknowledged as much. It is
rather difficult to ascertain what the precise role of the network operator would be in a
truly self-organizing mesh other than serving as a sole conduit for a monopoly infrastructure
product, and I cannot see anyone fulfilling such a role indefinitely. It well may be the
case that a mesh of meshes on a national scale is infeasible and that local meshes simply
cannot coalesce into an all-encompassing canopy, but if they can and do, the function of
the service provider must change radically. Technology pundit George Gilder speculated
on the properties that a nationwide fiber-based mesh network might exhibit in his book
Life After Television (W. W. Norton & Company, 1994), and he assumed that the service
provider’s role would consist merely of owning and maintaining the actual fiber plant, but
in a wireless mesh there are no actual links to own. The service provider’s place in such a
scheme is obviously at issue.
A final challenge is the attitude of entrenched wireline incumbents in the event that wireless
meshes begin to win acceptance. One could foresee such incumbents seeking some sort of
legislative or regulatory relief to preserve the de facto monopoly they enjoy today. And in the
United States one could easily see them prevailing against the interests of the public.
All of this does not preclude a network operator soliciting a bid or a proposal from a wireless
mesh manufacturer. All of the claims made by such manufacturers may yet be realized,
and meshes may eventually become the norm rather than the exception. I think, however, that
meshes, because they are relatively untried, represent a higher risk option than more traditional
architectures.
Performing Site Surveys and Determining
Link Budgets
A site survey is simply a determination of the extent of the interference levels in the frequencies
of interest and of the severity of obstructions and multipath at the precise locations in which
one wants to install terminals. Such a survey enables the network operator to determine if
unacceptable amounts of interference are present at various locales such that adequate signal
quality cannot be obtained, as well as the extent to which blockages restrict blanket coverage
in a given area. Ideally, the site survey should be an ongoing process and should encompass
every link in the network. In practice, something considerably less extensive will be performed
because of the prohibitive cost of deploying technicians at every location.
Site surveys are performed manually and painstakingly by taking innumerable measurements
with a radio spectrum analyzer and eventually with an actual radio transceiver. It is
grunt work, but a certain minimum surveying is required for informed network planning. It is
also one of the first steps a network operator should take, and if unlicensed spectrum is to be
utilized, it should be perhaps the second step after a determination has been made as to what
spectrum is available.
In theory, a site survey should encompass every location where either an access point or a
subscriber terminal may be situated, but of course the time and expense required to achieve
that theoretical ideal are enormous in the case of a large metropolitan network. Therefore,