Obtaining Roof Rights, Right of Way, and Access to Appropriate Buildings at Acceptable Cost

Almost every major wireless broadband operator faces the same challenge when planning and
building the network. How does one manage to place network nodes where they are needed to
serve the subscribers?
If one does not meet this challenge early in the deployment process, one’s chances of
succeeding with the operation will be nil. In the business of broadband services, access is
everything—the absolute precondition to moving forward with provisioning and ultimately
toward profitability.
Access requirements for the network operator will vary somewhat according to the frequencies
at which the network is operating, the types of customers sought, and the capabilities
of the equipment. A network targeting primarily MTUs and business high-rises will need to get
roof rights for the individual network nodes as well as the central base station(s). A network
that is serving residential customers will not. A network using strictly line-of-sight equipment,
will, all things being equal, require a denser infrastructure of base stations and thus will require
more roof rights or tower rights than a system using the newer non-line-of-sight (NLOS) equipment.
The cell size of the NLOS network will be smaller (see Chapter 5), but, on the other hand,
each base station will be able to reach more potential customers located within its effective
radius. To date, networks using line-of-sight equipment and operating in developed markets
have nearly always failed because the expense of building and maintaining a large number of
base stations has proven prohibitive.
Central Office and Main Base Station Facilities
Obviously, the first order of business is to establish a site for the initial base station and the
central office for the entire network operation. The central office need not include all the
administrative facilities of the network, but it should include the equipment essential for
anchoring the network, which would ultimately depend on the mix of services offered by
the network. Several considerations are significant here.
The antenna for the central base station needs to be situated at a position and at an elevation
where it will encounter the fewest obstructions between itself and targeted subscriber
sites and, as the network is built out, subsidiary base stations. This is true even if NLOS equipment
is employed, because a clear line of sight is always preferable.
Finding the right location can be difficult, though. A building that is considerably taller
than any of its neighbors or a peak overlooking the city or metropolitan areas is often ideal
from the perspective of minimizing obstructions, but it may be far from ideal in other respects.
Space within the city’s tallest structure may simply be too expensive to rent, and a mountaintop
is likely to be too remote to permit the placement of central office facilities. Another option
is to place a steel antenna tower atop a shorter structure, but often local ordinances will not
permit this. One can, of course, run a high-speed connection to a remote antenna, the usual
practice among radio and television broadcasters, but that connection will have to be capable
of handling all the traffic going through the hub with no bottleneck or reduction in throughput
speed. A fiber connection of that type may be unobtainable or too expensive, and a wireless
connection will have to be capable of fiberlike speed and of maintaining a high level of availability.
This may entail leasing millimeter microwave backhaul from another service provider
if one is operating in the lower microwave region.
To obtain affordable space for central office facilities, one may have to settle for a location
that is less than optimal in respect to signal distribution and customer acquisition, and such
considerations will inevitably have an impact upon the network’s growth potential. Because
the choice of central office and initial base station placement is so important, it is best for the
network operator to select a site prior to proceeding any further with the network and make
certain that it can be secured under favorable circumstances before constructing a single
access point.
Physical Requirements for the Central Office
During the acquisition process, careful attention must be given to space, power, and ventilation
requirements for the basic central office equipment as well as to the positioning of the
antenna. The operator will need to know how many standard rack units of space will be taken
up by the essential equipment and should have a fairly firm notion of what types if not brands
of components will be purchased prior to network launch. Chapters 4–6 provide guidelines on
what to look for in terms of equipment specifications.
At the least, the operator will require the following components for delivering even the
most basic service offerings.
First, operators need a base station transceiver attached to the antenna. In some cases,
this may be placed in a hardened enclosure adjacent to the antenna and in some cases in an
equipment room or closet. Since cable that runs from the radio to the antenna should be kept
as short as practical to avoid signal losses, it is not advisable to place the antenna on the roof
of a 50-story high-rise and the transceiver in the basement. Typically, such transceivers are
considerably larger and more powerful than subscriber units, and they feature redundant
architectures and backup power. Therefore, they require a certain amount of space, preferably
a sizable fraction of a cubic meter.
Most broadband wireless systems also include a special component that incorporates
essential software for managing the physical layer and may also include routing or switching
software. In all cases, this box will include what is known as wireless middleware, which serves to modify the Transmission Control Protocol/Internet Protocol (TCP/IP) data stream so as to
adapt it to the airlink. The design of such boxes is far from uniform, and in the first generation
of lower microwave equipment, a modified Data over Cable Service Interface Specification
(DOCSIS) cable data headend device was often employed. Today that approach is thoroughly
discredited, however, and indeed with the finalization of 802.16 and the production of equipment
embodying it, the network operator need not even consider such a makeshift. Generally,
the base station transceiver will be combined with the router/switch.
Second, the operator will also need an edge router whose output will go directly to the
radio transceiver, if the two are not combined in a single box. The size and power consumption
of this device will depend on the number of subscribers served. Most edge routers made today
are highly modular, consisting of a largish box with multiple slots taking a number of separate
blades, each of which handles a group of input/output (I/O) ports. The router is designed for a
certain maximum number of ports, and in most cases the operator chooses to buy additional
blades as needed until reaching the full capacity of the design. A fully loaded edge router will,
as a rule, take up several rack spaces and will have a power consumption in the kilowatts.
Carrier-grade edge routers cost thousands of dollars, but a small metropolitan network may be
able to get away with an enterprise-class router, which costs less than $1,000. In some cases, as
I have mentioned, the base transceiver will incorporate an edge router. Figure 4-1 shows a
Juniper edge router. Some products that are primarily edge routers perform other functions as well, such as
creating services, inputting and outputting protocols other than IP, and providing switching
functions within those other transport protocols. Such “Swiss Army knife” network elements
are popularly known as godboxes and are intended to provide the network operator with lots of
choices and a high degree of flexibility.
The utility of such devices is a matter of some contention in the telecommunications
world today. Little uniformity exists in the design approaches embodied in godboxes, and any network operator contemplating using such a device must carefully study its capabilities.
Depending on the mix of services the operator intends to offer, some such devices may be useful.
But typically the versatility comes at a price. The boxes incorporate custom designs and
often utilize proprietary elements, architectures, and engineering approaches and, in many
cases, represent staggering development costs that cannot be amortized even among a large
universe of users. Furthermore, none of the godboxes on the market today have been designed
with the specific needs and requirements of the wireless operator in mind; instead most are
designed to interface with optical networks.
Another essential element in the central office equipment rack is a server devoted to the
subscriber database. The same element may, depending on the size of the network and the
desire of the operator to assign the various networking functions to discrete physical platforms,
also contain the billing and provisioning software and may host the authentication
software as well; however, more commonly, in the interest of ensuring the highest degree of
security, authentication will be performed on a separate server. Radius authentication software
has become the de facto industry standard for telecommunications and large enterprises.
The central office may also, again depending on the mix of services, contain such as elements
as the following:
• A softswitch
• An IP telephony gateway (occasionally the two elements will be combined on one physical
platform)
• A content server for supporting “walled-garden” applications that are not resident upon
the public Internet but are available only to those who subscribe to the wireless broadband
network
• A video server for caching multimedia material to be streamed to subscribers or else
accessed on demand, or, alternately, for ad insertion
• A server for content management software
• A hardware security device for bulk encryption/decryption
• A satellite transceiver for accessing content
• An optical transceiver for interfacing with a metro ring or mesh
• A DSL access multiplexer (DSLAM) for interfacing with DSL links
Certainly other network elements are possible as well, and conceivably the central office
for a large metropolitan wireless operation could have two or more floor-to-ceiling racks filled
with equipment.
Any central office, large or small, should occupy a secure location where access to the
facilities is strictly controlled and the facilities are monitored at all times. In today’s political
climate considerations of physical security are not secondary, and the days when major Internet
access points were left untended in unlocked rooms in parking structures are long gone.
The central office should have an uninterruptible power supply (UPS) or supplies capable
of powering the central office equipment complement for at least 48 hours. Such backup
power may utilize banks of batteries, fuel cells, internal combustion generators, or combinations
thereof. The important point is that the backup power supplies deliver dependable AC power at a fixed voltage and with low values of line harmonics, preferably less than 1 percent
under conditions of load. In this context, the low-cost UPSs utilized in business offices are
unacceptable. Medical-grade backup power should be the standard, with appropriate power
conditioning apparatus to maintain a clean, smooth 50- or 60-cycle sine wave, and the system
should be designed to provide ride through, that is, continued delivery of electrical power
while the backup power-generating system is coming up. The specifics of backup power facilities
design are quite involved and are beyond the scope of this book, but the objective is
simple—to ensure that the central office will continue to operate perfectly in the case of a
power blackout or brownout. My recommendation is that the network operator retain a consulting
engineer with demonstrated expertise in power quality.
The facility where the vital equipment resides should have personnel on the premises at all
times to control access and should be provided with ancillary surveillance and alarm systems
communicating back to a highly secure monitoring facility.
Equipment should be professionally mounted on steel or aluminum racks, and cable
management accessories should be employed so that reconfigurations and additions to the
network can be easily managed. All equipment should be easily accessible to technicians, and
racks should be situated with sufficient clearance to permit any connection to be manipulated
without the removal of a component from its rack. A centralized command console with a
high-definition monitor and comfortable seating for the network manager is advisable.
The equipment racks should rest on a raised floor as a safeguard against natural disasters.
The interior should be climate controlled and properly ventilated, and auxiliary independently
powered climate-control systems should be in place in the event of a power loss. The structure
enclosing the equipment should be highly fire resistant, and highly impact-resistant glazing
should be installed. Doors and locks must be completely resistant to being forced open with
hand tools.
All operating software and customer records must be backed up continually and mirrored
at a secure facility. Retaining a reputable disaster recovery firm to mirror the entire computing
operation at the central office is also recommended in the event of a large-scale catastrophe
that destroys all or part of the central office.
All these recommendations constitute best practices and are entirely typical of traditional
telecommunications incumbents, but they are not observed by all broadband access providers,
and the degree to which they are absolutely essential is debatable. If one is providing
nothing more than high-speed access to residential customers, then one may reasonably opt
for a lower degree of security and infrastructure integrity at the central office, though one
would certainly have strong reason to protect customer records. If, on the other hand, one is
providing essential telephone service, then one incurs a grave obligation to the subscriber and
to the larger community. Business users, particularly larger enterprises, will also expect that
the network will be well secured and equipped to survive disasters. The loss of a data link for
hours or days can be devastating to a business, especially one involved in conducting online
financial transactions and recording such transactions. The degree of legal liability facing a
carrier or service provider that fails to follow such best practices is uncertain, but no sane individual
would want to compromise the business of a major subscriber or jeopardize public
safety because the network failed to perform adequately.