The realities of spectrum--Page 2.
For example, in March of this year NTIA announced that 1755 to 1850
MHz—95 MHz of prime spectrum real estate—would be made available for
auction under the President’s 2010 Spectrum Initiative.
Their detailed analysis estimated the total cost of relocating current occupants of this band at a whopping $18 billion!
cases where relocation costs may be even higher, such as in the 3550 to
3650 MHz band (selected in late 2010), where numerous military radar
systems operate, the NTIA has recommended geographic sharing of the
This will be implemented by creating significant
exclusion zones where commercial broadband will not be permitted, for
example within 200 miles of coastlines, to prevent interference from
shipboard radar systems.
This can create problems, or at
least increased expenses, for commercial providers as they will need to
have end-user equipment that operates in multiple bands if they want
Network Testing and Measurement
As discussed above, spectrum is a very valuable resource to acquire.
Once you have it, the challenges are in making the best possible use of it to maximize the return on investment.
By regulation, the types of modulation that can be used in a given spectrum are often tightly controlled and specified.
the constraints of their license, renters of the bandwidth need to be
able to monitor their spectrum and identify problems introduced by other
emitters that may be present (both intentional and unintentional) as
well as make sure their equipment isn’t operating outside of the
regulated performance thereby impacting other adjacent spectrum owners.
Network Testing and Measurement is a key component of the practical optimization of a network’s performance.
Problem identification in large-area wireless networks once deployed is almost always a multi-tier solution.
can be identified, for example, by customers or users reporting
problems of poor coverage areas, network discovered issues in two-way
communications via statistics, and via field test and measurement tools.
first type of issue identification is via customer complaints and is a
common way a provider first finds out a problem may exist in an area of a
This is especially true for higher-use
areas where multiple customers may simultaneously complain, providing
for more confidence by the network owner that the network itself or the
transmission equipment may be misaligned or having other problems.
providers run a support center that accumulates customer support
tickets and alerts management if a threshold is reached and, therefore,
that a technician should be deployed to investigate the problem further
using field test and measurement equipment discussed below.
discovered network issues are a second method of problem
identification, and is an area that in cellular network planning is
often referred to as switch statistics or network monitoring.
technique is most useful in two way communication systems such as
cellular networks where full-duplex (two way transmission) is in use and
a feedback path is available, and a well-developed system can often
detect problems before customers are even aware of them.
is performed by statistically monitoring key performance indicators
such as dropped calls, average data throughput rates, and use trend
analysis for known problems, and will alert management that a specific
node or station of the network is experiencing sub-optimal performance.
type of analysis is so important that in most cellular service
providers, KPI monitoring is tied to bonuses and frequently a factor in
promotion within the organization.
With this level of
visibility, each ‘market’ manager within the organization is highly
incentivized to reach for continual improvement.
problem area is found that can’t be solved directly using the
statistical data gathered either through retuning of the frequency plan
or other optimization of parameters, the next step is to deploy field
test and measurement equipment to the area for further analysis.
Field test and measurement tools are the heavy hitters in the network optimization area.
only are they used to periodically cover and geographic area to assure
network compliance and search for problem areas, they are also the
method used to solve/diagnose and debug problems that exist within the
network and to resolve issues that couldn’t be addressed by simple back
There are numerous types of tools that may be used, and often multiple tools are used for the stickiest of problems.
of such tools are Engineering Test Tools, Field Spectrum Analyzers,
Drive Test Measurement Equipment, and--just as importantly--the
knowledge, experience, and skills of the diagnostic technician assigned
to the problem area.
Engineering Test Tools are
generally either purpose constructed, or feature-augmented end user
equipment, that is designed to assist a technician in uncovering a
problem within a network.
Examples of these in cellular test and measurement are QRC’s ICS-Qp, Anite’s Handy, and Ascom’s Pocket TEMS.
products run on the same mobile phone that customers use but have
additional software and processing to report on configuration
information such as quality ratios, overhead information, neighbor
lists, and more precise power and signal to noise measurements.
when using this type of tool, an experienced network technician is able
to log and observe network problems, and using post-processing software
such as Actix’s ActixOne to map an area to find physical issues such as
new construction, bad tower equipment, and suboptimal alignments and
adjust the network accordingly.
Once the problem is identified then the correct solution can be employed.
A field spectrum analyzer is a man-portable spectrum tool such as Agilent’s N9912A or Rhode and Schwarz’s FSH4.
the hands of a knowledgeable user, interference from other signals such
as adjacent networks, bursty noise such as meg-welders and other
equipment that may generate interference.
It can often
also be used to verify the compliance of the network as well with the
licensing of the spectrum. Drive test and whole network testing
equipment are the final category of analysis.
category is comprised of advanced Engineering Test Tools that are
designed to be deployed in a moving vehicle to measure the network over a
Examples of these tools include QRC’s ICS-210 and Rhode and Schwarz’s ROMES.
tools are different than Engineering Test Tools in that they measure
multiple providers and networks simultaneously and can test and measure a
network from multiple users’ perspectives in a single piece of
Many of these tools also have advanced
debugging and diagnostic equipment such as built in spectrum analyzers
to further help in the diagnostic and debugging of the network and to provide additional data to be used in network frequency and planning.