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Building a Redundant and Resilient College Network 14 How to

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January/February 2007
BICSI news
advancing information transport systems
Volume 28, Number 1
Building a Redundant and Resilient College Network 14
How to Work with the Authority Having Jurisdiction 22
The Wi-Fi Path Loss Equation and Antenna Specifications 26
Increasing Power Margin with High-Performance Optical Fiber 34
Testing Multimode Optical Fiber: Importance of Controlling Launch Conditions 38
2007 BICSI Officers
President’s Message
PRESIDENT—John Bakowski, RCDD/NTS/OSP/WD Specialist;
St. Catharines, Ontario, Canada; 905.646.5100;
PRESIDENT-ELECT—Edward Donelan, RCDD/NTS Specialist; Telecom
Infrastructure Corp.; Pawling, NY; 845.855.4202;
SECRETARY—Peter P. Charland III, RCDD/NTS/WD Specialist; CET
ITS Consulting; Framingham, MA; 508.868.9080 ;
TREASURER—Brian Hansen, RCDD/NTS Specialist; Leviton; Rosemount,
MN; 651.423.9140;
Specialist; SIEMON; Watertown, CT; 860.945.5889;
RCDD/NTS/OSP Specialist; Wilson Technology Group, Inc.; Brooksville, FL;
RCDD/NTS Specialist, CISSP, CPP; CommScope Enterprise Solutions;
Columbus, OH; 614.853.3812;
AT&T; Bellaire, TX; 713.567.1234;
Specialist; I T Design Corporation; Westlake Village, CA; 805.777.0073;
Specialist; Bell Aliant Regional Services; Moncton, NB Canada;
RCDD/NTS/WD Specialist; Qualitas Limited; Hertfordshire, UK ;
+44 1708 733 032;
800.242.7405 or 813.979.1991;
COMMITTEE CHAIRS: BICSI CARES—John Discenza, General Cable Corp;
Weston Ontario, Canada; 416.791.2401; • CODES—Phil
Janeway, RCDD; Time Warner Telecom; Indianapolis, IN; 317.713.2333; •EDUCATION ADVISORY—Michael Collins,RCDD; SBC;
Bellaire, TX; 713.567.1234; • EXHIBITOR ADVISORY—
Kurt Templeman, Sumitomo Electric Lightwave; Research Triangle Park, NC;
919.541.8100; • ETHICS—Carl Bonner,
RCDD/OSP/WD Specialist; Network Communications Supply Company;
Milton,FL; 850.626.6863; • INSTALLATION— Daniel
Morris, RCDD; Kitco Fiber Optics; Virginia Beach, VA; +1 757.518.8100; • MEMBERSHIP & MARKETING ADVISORY—Edward
Boychuk, RCDD; Convergent Technology Partners; Flint, MI; 810.720.3820; • NOMINATING—John Bakowski, RCDD/NTS/OSP/WD
Specialst; St. Catharines, Ontario, Canada; 905.646.5100; jbakowski
RCDD/NTS/OSP/WD Specialist; Communications Network Design; Haysville,
KS; 316.529.3698; • STANDARDS—Theron J. (T.J.)
Roe, RCDD; Garrett Com, Inc.; Hockessin, DE; 302.235.0995; •
NTS/OSP Specialist; RTKL Associates, Inc.; Baltimore, MD; 410.537.6070;
Seize the Day
The phrase Seize the Day, which appears in
music, movies and literature, means many different things. For me, this term is a recommendation
on life—that time is short and we all should make
the most of what we have and what we have been
given. Seize the Day should also be an important
beacon for everyone working in the information
transport systems (ITS) business.
John Bakowski,
There are some individuals who see limits in
line of work. After all, a lot of IT managers and
WD Specialist
remain preoccupied with the more visible
and glamorous active equipment—even though
none of the routers, cameras and controls will operate without a properly
designed, installed and tested cabling and wireless infrastructure.
However, when you look closely at the ITS business today, you will see
that we actually work in an industry with more limitless opportunities
than ever. This holds true whether you are an apprentice in ITS, the owner
of an established design/build contracting firm, or systems integrator.
On one hand, there are so many directions you can take as part of the
ITS industry—foreman, designer, building owner, trainer, product manager,
consultant, project manager, business owner and many others. These are
all opportunities available to you, assuming you want to seize them by
growing your own ITS knowledge, experience and skills.
On the other hand, the scope of ITS is broadening, especially for us—
the specialists with entirely unique talents around cabling and wireless
infrastructure. A dozen years ago, we all pretty much worked with voice
and data systems. Now, BICSI members install the infrastructure and hardware for security, AV and building automation systems (BAS), anything
that is IP centric. As a result, BICSI members are in an enviable position—it
seems the complexity of our business makes it easier for us to master the
other ITS disciplines, rather than vice versa. Again, this is opportunity for
the taking—for those who seize the day by taking courses and training,
and earning new credentials, to advance their career.
If you really take Seize the Day to heart, you know that none of us is limited by what we know today, that all of us has the potential to grow and
learn, whether it is for income, self-fulfillment or career development. It is
comforting to know that you work in an industry that offers so many
avenues for development and advancement. The opportunities are out
there for you—if you choose to seize upon them.
Looking Forward to 2007
I want to thank David Cranmer, RCDD, for accepting the position of
Executive Director for BICSI. We are thrilled to have David’s combination
of strong management practices, integrity and industry knowledge to guide
the staff. I also want to thank the volunteers who write training content
and manual chapters, and work on other committee projects, to help
evolve the products and services for the membership. BICSI members are
the ITS professionals who are positioned best to capitalize on convergence
in the marketplace; it takes volunteers like you to create the learning platforms we all need to Seize the Day. Lastly, I thank the BICSI staff for working through a difficult year of changes without losing their professionalism
and high standards. We can’t do it without you. .
January/February 2007
BICSI Executive Director
Be Careful What You Wish For
Many of you may remember
that I lived in Tampa for about 10
years from 1994 to 2004 and,
David C. Cranmer,
during that time, the goal had
always been to move to
California to retire. But in 2006,
after being in northern California for less than two years,
imagine my surprise when I got a call from BICSI
President John Bakowski asking if I would be interested
in coming back to Tampa and serving as the interim
Executive Director for BICSI.
I confess it was not an easy decision. I spent a great
deal of time pondering the pros and cons of the offer
but, in the end, I was honored to serve as the interim
Executive Director. I even went so far as to tell John that
I would not put a time limit on the appointment so that
the Executive Director Search Committee would not feel
any undue pressure to find a permanent replacement.
Upon arrival in Tampa last June, some board members
asked if I would submit my name to the search committee as a candidate for the permanent position. This turn
of events was a horse of a different color. More sleepless
nights ensued as I struggled to come to grips with returning to Tampa and giving up my business as an expert witness to take over this huge responsibility.
To give you some historical perspective, I attended my
first BICSI conference in 1980 and over the years I have
served on the Board of Directors and a term as its president. I also have been a contributing author on the
Telecommunications Distribution Methods Manual (TDMM),
Customer-Owned Outside Plant (CO-OSP) Design Manual,
and the Information Transport Systems Installation Manual
(ITSIM). In addition, I chaired the Installation Committee
from its inception, audited BICSI’s Authorized Training
Facilities, spoke at conferences and many other duties
that I can’t even remember as of this writing. The point
is that I have a long history with BICSI—volunteers,
members and staff—and I feel a certain responsibility to
this fine association. Because of these feelings, I agreed to
have my name submitted.
Advancing Information Transport Systems
Well, you all know the outcome. I was appointed
Executive Director, effective January 1, 2007. However,
I want to assure all of you that the Executive Director
Search Committee did a thorough job of evaluating all of
the candidates to find the right person. I thank them for
their confidence in me.
In retrospect, accepting the position at BICSI was an
easy decision. After working with BICSI for 26 years,
I have a deep-seated connection with the information
transport systems (ITS) industry and its members.
Already, I have made changes to strengthen our staff and
its responsiveness to members and volunteers. Our strategic plan sets a path for continued growth both in the
U.S. and internationally, but it takes industry people to
understand many of its nuances.
Because BICSI needs industry people in key positions
to effectively implement this plan, I recently hired back
Richard Dunfee as Director of Professional Development
and Credentialing and I’m confident of his ability to
guide that group.
At BICSI World Headquarters we understand our job is
to serve the Board of Directors, volunteers and the membership at large. On staff, we clearly recognize that without the direct input and guidance from volunteers and
committees, the association would become weak. I assure
you that you can expect the quality of everything we do,
from manuals to member services, to continually
improve. The last half of 2006 was good for BICSI and its
members and we look forward to even more success in
2007. If you ever feel the need to complain, complement
or just chat, I’m always available. I look forward to working with all of you in 2007. .
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On the Cover
... ...
Smart Card
for Physical
Access Control
Contactless smart cards offer applications
beyond simple access. BY MARK PETERSON
Advancing Information Transport Systems
ew technologies can create
market confusion as designers, installers and end users
struggle to identify the elements that enable effective
product evaluation and
deployment. This is evident
as contactless smart cards
become the de facto standard
for physical access control.
Although MCU-based
(microcontroller unit or chip)
smart card development began
back in the mid-1980s, only
recently is the pace of smart card adoption in the physical access control market surpassing other legacy technologies. As market demand continues to increase,
those who design, specify or deploy smart cards for
physical access control are looking beyond marketing
hype to identify the factors that will ensure a valid contactless smart card deployment for their customers.
Historically, the limited functionality of legacy card
and card reader technologies (e.g., magnetic stripe, bar
code, Wiegand, and low frequency proximity) made
product choices relatively easy. For the most part, these
technologies are single purpose: transferring card data
to a reader and the reader in turn sending the data to a
back-end access control system (controller and application software) to make an access decision—granting or
denying access based on the cardholder’s access privileges. Therefore, historically product choices were driven in large-part by product availability, reliability,
brand confidence and customer service.
Today, contactless smart cards provide a far more
advanced technology platform that increases product
performance and expands smart card use into other
business processes beyond physical access control. To
choose the right product, it is essential to have a solid
understanding of today’s smart card technology and its
Drivers for Smart Card Growth
There are several reasons why smart cards are becoming so popular for use in physical access control systems.
One of the most topical, and sometimes most controversial, is the U.S. Government’s post 9/11 mandate for
increased Personal Identification Verification (PIV),
incorporating the use of a smart card based on the government’s Smart Card Interoperability Standard. As mandated by Homeland Security Presidential Directive
(HSPD-12), the National Institute of Standards (NIST)
January/February 2007
has issued the Federal Information Processing Standards
(FIPS) Publication 201-1: Personal Identity Verification for
Federal Employees and Contractors, 2006 March.
Publication 201-1 specifies the architecture and technical requirements for a common identification standard
for federal employees and contractors. The overall goal is
to achieve appropriate security assurance for multiple
applications by efficiently verifying the claimed identity
of individuals seeking physical access to federally controlled government facilities and electronic access to government information systems. As with many such activities, the commercial marketplace follows suit as the government leads the way in setting the standard.
Several other factors are facilitating the trend toward
smart card adoption. With an increase in public attention
to the protection of personal data, the built-in data security features offered by smart cards are becoming very
popular. Smart cards also provide the ability to not only
read data from a card, but also to write data to a card.
This increased data storage creates a platform for diverse
applications to store specific data on the same card.
This feature makes smart cards a valuable tool for
deploying biometric technology since biometric templates can now be stored on the card. The result is a single card that can securely store access control data, biometrics template data, cashless vending data and other
data, increasing the overall value of the card across other
aspects of the customer’s business.
Yet with all of the increased data security and operational flexibility smart cards provide, one of the most
powerful market drivers of smart card adoption is cost
parity with legacy technologies. Contactless smart cards
offer a significantly enhanced feature set along with superior data security at essentially the same cost of the legacy 125 kHz Prox (low frequency proximity) technology.
Although still a viable technology, there is no significant
reason to use 125 kHz Prox for new installations.
Comparing Smart Card Technologies
By far, the legacy technology of choice for physical
access control cards and readers has been 125 kHz Prox.
With this technology, a radio frequency identification
(RFID) chip and antenna are sandwiched inside an ISO
standard sized card. When the card is presented in the
electromagnetic field of the card reader (thus powering
up the chip), the card format data is transmitted via RF to
the card reader. This proven and reliable RFID technology
became popular primarily due to its ease of use and
reduced maintenance characteristics due to no moving
parts. Prox is based on de facto industry standards rather
than any ISO or IEC standards.
Chart 1. Comparing smart card technologies.
13.56 MHz
13.56 MHz
125 kHz
ISO/IEC 14443
ISO/IEC 15693
Read Range
Up to 10 cm
(2-3 cm typical)
Up to 1 meter
(6-8 cm typical)
Up to 1 meter
(6-8 cm typical)
Memory Capacity
64 to 64K Bytes
256 to 4K Bytes
8 to 256 Bytes
Data Transfer Rate
Up to 848
Up to 26.6
Up to 4
Read/write ability
Read only
Mutual Authentication
Advancing Information Transport Systems
Some of the characteristics of 125 kHz Prox are:
• 125 kHz operating frequency
• Read only
• Up to one meter read range
• 4 Kbps data rate
• 8- 256 Byte memory storage
• Vendor dependant data security
As compared to contact smart cards, contactless smart
cards provide the physical access control market with vastly superior functionality while providing an identical user
interface to the widely deployed 125 kHz Prox technology.
This familiarity of use makes contactless smart cards a natural next generation solution for physical access control.
Today’s contactless smart card products are, for the
most part, a plug-and-play replacement for 125 kHz Prox.
Contactless smart card products operate in the same
manner—access system components are wired the same
way and they use the same card formats (internal card
numbering sequences) of legacy technology products.
This allows designers and installers to easily deploy contactless smart card technology in new installations as well
as migrate legacy systems toward using contactless smart
card technology.
Most importantly, contactless smart card technology is
a standards-based technology. The two most recognized
contactless smart card standards are ISO 14443 A/B and
ISO 15693. While these standards deploy similar operating characteristics, ISO 15693 is viewed by many as more
conducive to physical access control due to its ability to
provide longer read ranges, which is more like those the
market is familiar with when using 125 kHz Prox. Chart 1
compares operational characteristics of 125 kHz Prox
with both ISO 14443 and ISO 15693 technologies.
It is important to note that being standards-based only
creates the potential for interoperability. Being standardsbased does not ensure interoperability. In fact, in the case
of contactless smart cards, once the cards are properly
and responsibly provisioned (meaning data is stored in
specific memory location(s), and the keys used to protect
the data are changed to be unique to that deployment),
the contactless smart card solution is essentially proprietary to that customer.
For example, a MIFARE or DESFire (14443 brand
names) solution purchased from one source most likely
will not be compatible with a MIFARE or DESFire product
purchased from another source because the data size,
location and security will be different from supplier to
supplier. Some end users have found out the hard way
assuming that selecting a technology used by several
manufacturers will provide their client with interoperability that will allow for future sourcing options. They are
disappointed when they discover that they have
unknowingly created a situation where they must solely
source from the initial supplier, eliminating any chance
of competitive purchasing environment for the future.
Tips for Selecting Smart Card Systems
Here are a few tips to consider when selecting a contactless smart card provider to be used with your physical
access control solution:
Select a technology that offers the desired operational characteristics. For example, if maximum read range is a design
consideration, make sure to select a technology that provides the desired read range (e.g. ISO 15693 vs. 14443).
Chart 2. Sizing for biometric applications.
Biometrics Technology Type
Advancing Information Transport Systems
Sample Template Size
9 Bytes
96 Bytes
250 Bytes
512 Bytes
1,300 Bytes
1,500 Bytes
2,000 – 10K Bytes
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Select a technology that is deployed across a comprehensive
product line. Ensure that your provider offers a full
product line, including multiple form factors, multiple
mounting options, keypad options, long range options,
and multiple technology units.
Select a product family that is available from multiple sources.
History has shown that card and reader selection often
outlives the access system selection. Also, vendor relationships can change unexpectedly. Therefore it is good
business to select a product from a manufacturer with a
wide and diverse distribution channel to ensure compatible products can be purchased from multiple alternate
sources if necessary. For businesses that operate globally,
ensuring the distribution channel operates globally
should be considered.
Ensure selection of a contactless smart card with sufficient
memory size and secure application areas to accommodate
data for other future applications. Understand how your
customer may potentially benefit from a smart card in
the future. Make sure the card you select has sufficient
room to accommodate not only today’s data, but also has
room for the data that may be loaded on the card
in the future. A good example is biometrics. Depending
upon the biometrics technology selected, the size of the
Advancing Information Transport Systems
biometric data template varies greatly. Chart 2 shows
rough-order-of-magnitude biometric template sizes:
When using the card for other applications beyond access control, select a technology that is utilized by a comprehensive list
of application providers. In order to gain maximum value
from the contactless smart card investment, it is important to make sure that a wide range of application
providers uses the technology selected. Ask your contactless smart card provider for a list of approved application
providers that utilize their technology.
Reading the CSN (Card Serial Number) is not an effective
identifier for access control. Read the fine print. Some smart
card products merely read the CSN as the card identifying
data. The CSN is a unique number programmed into each
chip at the point of manufacture. It is intended as an ISO
mandated anti-collision element to identify data coming
from multiple cards being presented simultaneously to a
single reader. Unlike the data stored in the memory of a
smart card, the programmer has no control over the length
or format of the CSN. More importantly, there is no security associated with the CSN. Any ISO compliant reader can
read the CSN since it is not secured by a key or other security feature. Reading the CSN as the card identifier does
not leverage any of the benefits provided by smart cards.
The data stored in memory should be secured with a key. As
discussed earlier, data locations within the contactless
smart card chip are secured with a key. The key is like a
password that defines access privileges for the protected
data area. If multiple applications are storing data in individual memory locations, each location should be
secured with a unique key to prevent intentional or accidental access or corruption of data. Some providers leave
keys in a default condition, exposing the programmed
data to tampering. A properly provisioned smart card
makes responsible use of the inherent security features
offered by the contactless smart card technology.
Give your customers using legacy technologies multiple options
to migrate to contactless smart card technology. Be sure to
select a provider that offers maximum flexibility for
migrating from legacy technologies. Multi-technology
readers provide the capability to read cards from both
legacy technologies (e.g., 125 kHz Prox) and new contactless smart cards. These units are valuable migration tools
for clients with large legacy card populations, allowing
clients to maximize their existing card investment and to
replace cards over time. Multiple technology cards
employ a mixture of technologies into a single card,
allowing them to be read in legacy technology readers as
well as new contactless smart card readers. Multiple technology cards can include Wiegand, 125 kHz Prox, magnetic stripe, bar code, contactless smart card and contact
smart cards. Having both options (multi-tech readers and
multi-tech cards) offers the maximum options to help
make the migration process as smooth as possible.
As with other convergence technologies, smart cards
provide users with value beyond the role of a secure
physical access control technology. Organizations can
also benefit from the increasing selection of non-security
applications enabled by this technology: manufacturing
control, cashless vending, point-of-sale, copy and print
management, and event management, to name a few.
This increased value comes at a very reasonable price,
comparable to that of the limited 125 kHz proximity
products. However, this increased value can only be realized if designers and integrators properly select and
deploy smart card products that meet the anticipated
needs of their customers.
As the market responds to the increasing demand for
smart cards, they must also begin to identify the issues
that affect their selection of the best products to incorporate into their designed solutions. This takes an understanding of smart card technology fundamentals beyond
the sometimes vague information contained on sales
brochures. The flexibility and capabilities afforded by this
technology can create a real danger of painting your cus-
tomer into a corner if cards and card readers are not
selected, provisioned and deployed properly. Any choice
of cards and readers should provide customers with a
wide selection of interoperable sourcing options for the
future, too. To augment selection criteria, industry professionals are looking beyond the technical specifications
toward the issues surrounding the business of smart
cards. Sourcing options, interoperability, and after-sales
service and support are becoming more important than
ever. System design and integration professionals who
embrace smart cards and the diversity of smart card
applications are able to differentiate their company by
distributing the value of the customer’s smart card investment across other areas of the organization. .
Mark C. Peterson
Mark Peterson is director, intelligent technology
design resource group, for HID Global, a leading
manufacturer in the access control industry.
For more information, contact Mark at
+1 303.453.4006 or
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January/February 2007
Building a Redundant and
Resilient College Network
Best practices design ensures the network will easily adapt to
changing technologies. BY RICHARD JOHNSTON
Few industries have been transformed by computers and networking as much as higher education.
Spanning from years ago when students stood in
line to collect punch cards to register for courses to
today’s Internet accessible course content and potential to
earn degrees without setting foot on a campus, the network has grown into a vital component for all colleges
and universities. This article reviews the best practices and
processes undertaken by Suffolk County Community
College to implement an enterprise-wide network to support the institution for next 10 to 20 years.
Advancing Information Transport Systems
Suffolk County Community College is located on
Long Island, New York with a network that spans 80
miles from the western border of Suffolk county to
Montauk on the southern fork. The college has three
campuses—the Grant Campus in Brentwood, the
Ammerman Campus in Selden, and the East Campus in
Riverhead—as well as several satellite sites that offer
courses and programs within local communities. More
than 24,000 students and 2,000 faculty and staff use the
network. Classes are offered seven days a week with start
times as early as 6 a.m. and end times as late as 10:30
p.m. College programs range from traditional liberal arts
to special programs such as automotive engineering and
veterinary sciences.
The initial challenge revolved around a patchwork of
many independent and incompatible networks, with
devices operating over DECNet, Novell, AppleTalk,
NetBIOS and TCP/IP. Cabling was varied and there was
no governing master plan or guidelines on how to
expand the network. It was through the process of documenting what existed that naturally led to a planning
document to consolidate the network and repair or
replace the infrastructure.
In this early phase, lack of documentation was a frustration that delayed understanding of the existing network. By researching how to communicate best practices on building infrastructure, the most successful
implementations followed a basic concept of a layered
approach. After all, the network protocols finding
acceptance in the marketplace had layers, as well as the
methodology for interconnecting devices. The capabilities of the telecommunications services were layered.
Even the organization of the college—students, faculty
and administrators—was presented in layers. Therefore,
the approach to building the network was to be accomplished in layers. By constructing layers within the
infrastructure and building upon the supporting parts of
each, a full stack could be completed over a period of
time while maintaining the operation of current systems. Today, the layered view of the world continues
across the college in staff responsibilities, project evaluations and scheduling priorities.
Building the Network
Building a large-scale network is a never-ending task
at the college because limited staffing must be balanced
against long days of classroom schedules. This creates a
cyclic problem—by the time an upgrade plan is finished, new technology has been introduced and the
installed components will have a shorter operational
life. To get ahead of this process, larger projects are done
with larger staffs. This requires a temporary staff that is
knowledgeable of the project and the goals. Suffolk
acquired additional staff by contracting with cabling
installers, equipment manufacturers and VARs and was
able to tap extensively into their expertise.
Since the college is part of the county government,
regulations require large projects to follow an RFP
process. Two factors of this process assisted the college
in achieving its goals:
• The RFP must have exact descriptions of the environment, technical details, scheduling, and the desired
goals (work, equipment, or talent).
Best Practices Employed by Suffolk
County Community College
Design twice, implement once
• Use a test bed to verify anticipated outcome
Document the network based upon layers
• Cable IDs (fiber strands or pair numbers), jacks
and locations
• Circuit IDs, device ports and parameters
• IP addresses and subnet
Document your standards and practices for
others to follow
• Cabling and wiring conventions
• Network IP address allocations and VLAN usage
• Device naming or numbering conventions
Have a multiyear plan
• Statement of goals for short and long term
• Include current network structure
• List of facilities locations (MDF, IDF,
electrical closets)
• Project descriptions, schedules and
equipment lists
• Long term project information
Use temporary staff to augment
permanent staff
• Use expertise from contractors, resellers,
and manufacturers
• Maintain relationships to eliminate
learning curve
• Explain future plans and schedules
• Require certifications
Leverage other projects to build infrastructure
• Participate in renovations and construction
• Include long range goals in plans
• Build for the future using today’s dollars
Use an RFP approach even without bid
The RFP process requires exact specifications
Define equipment and statement of work
Review schedule prior to a commitment
Ensure better understanding of project
Use other best practices and standards
• Reduces workload
• You don’t have to reinvent the wheel or be
a trailblazer
• Pick and choose practices which match your
• Leverage on the research done by others
January/February 2007
• Multiple firms compete and get reviewed, which leads
to a winning firm that has the capabilities to perform
the work or deliver the equipment.
The college has been successful with this process and
has worked with several firms that have continued the
business relationship long after the initial contract was
One of the first projects addressed growth of the network and the use of PCs within the college. The goal of
the Universal Connectivity Project was to provide PCs
and networking for each classroom, faculty and staff
member. This allowed rapid construction of the access
layer of the network. New telecommunications rooms
(TRs) were constructed to terminate cabling and install
the hubs. The “space wars” on gaining proper square
footage and location for TRs was a study in diplomacy,
but the result was a dramatic increment in the scale of
the network.
Installation of a large number of cables, patch panels,
racks, and hubs required several teams to build the TRs,
based on a standard that would adapt to individual circumstances. To assist in this process, the first draft of the
college’s Wiring and Cabling Standard was instituted.
This documented the cable requirements for classroom,
computer lab, lecture halls, faculty office, clerical spaces
and administrative offices. The standard addresses the
types of cables and the acceptable products to be used.
This document continues to be updated for new technologies, such as wireless, VoIP, and new indoor and outdoor spaces.
With addition of so many additional devices in a single project and with the college’s continued growth with
the purchase of new equipment every year, the network
was growing dramatically. Bottlenecks within the interbuilding links and greater demand for Internet access
were causing issues. Resolving these problems required
two projects to jump the support level of networking
services within the college well beyond its current needs.
Advancing Information Transport Systems
The first was a WAN upgrade project, which replaced core
switches and routers. The second project was a LAN
upgrade project, which replaced the distribution layer of
network equipment and funded the installation of an all
optical fiber network to every building’s main distribution frame (MDF) and to each intermediate distribution
frame (IDF). These projects were successful because of
well-trained contractors and well-defined plans.
In rebuilding the distribution layer, the college
installed additional conduits and manholes to provide
new paths to existing buildings and to create the interconnect points for new buildings. The use of a cabling
company with a BICSI Registered Communications
Distribution DesignerВ® (RCDDВ®) with an Outside Plant
(OSP) Specialty provided the expertise to design an infrastructure with a projected service life of more than 20
years. The continued business relationship with the
cabling company allows the college to plan several years
ahead and have the resources available when needed. The
use of an RCDD ensures that implementations are performed to specification and that short- and long-term
goals are understood and planned.
During the LAN upgrade project, reliability and survivability of the TRs was taken into account. Each MDF and
IDF had its electrical power sourced on emergency circuits with generator backup. To offer equipment protection, UPS units were installed as well as network and
temperature/humidity sensors that communicate back to
a central management device that monitors and pages
staff if faults or environmental violations occur. This
allows 75 TRs to be monitored 24/7 with minimal staff
Along with network growth within the college’s existing buildings, the college constructed new buildings for
new instructional areas. The largest of these buildings
was the health, sports and education facility on the
Grant campus. This is a large athletic and academic
building constructed as seven attached buildings with
two three-floor academic wings, a field house with a 200
m track and bleacher seating for 3,000, a health club
with pool, and the county’s police academy. The complex
is so large that it is designed with five MDF wire closets
(one per wing) interconnected with singlemode and multimode optical fiber cable. In fact, every classroom has a
hybrid cable of two singlemode and four multimode
strands housed in a metal BX-style cable that terminates
in the lectern. This allows streaming video or Internetbased presentations into each classroom. More than
120,000 feet of this hybrid cable is used to interconnect
the academic and lecture spaces, including optical fiber
outlets embedded alongside the main basketball court for
video and presentations. Fourteen access points provide
wireless network coverage in the field house, which is
used for athletic events, conventions and shows.
The most recent upgrade to the network and the most
complex design change was the replacement of the college telephone system with 1,500 VoIP digital handsets
and 800 analog gateway ports. The old telephone system
had five PBX nodes and supported multiple departmental
PBX systems. The new system has redundant servers for
each campus and failover to off-campus servers. Use of
both a VAR with prior experience with the college’s network and direct manufacturer involvement greatly assisted in making the change. Seven months of planning and
network modifications prepared the way for a fast implementation. The equipment was delivered in mid-February
and cutover was on April 10. The VAR was able to provide 20 staff to assist in delivery, unpacking, installation
and testing of 1,200 telephones within five days. On the
day of cutover, nine T1 circuits were moved and 650 analog lines were re-circuited. After performance and acceptance testing were completed, the system was successfully
turned over to the college.
Of the more important features incorporated into the
new telephone system was 911 support. The new 911
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server reports the exact office location—wing, floor,
building, and address—to local authorities, instead of
merely showing the listed address of the college.
Providing this information decreases response time in an
emergency. Before the new system was implemented, 911
would direct the emergency equipment to stop at the
campus security office to ask where to go. To have the
911 system operate correctly, exact location of handsets
must be documented in a central database. By labeling
each outlet and jack per TIA/EIA 606a standards, the
information was easily collected and the database created. Normally, documentation is improperly done or
undone because of cost cutting. Now, it is an integral
requirement that can save lives.
What the Network Can Now Do
The projects that created the college network have
provided a robust and redundant network that self-heals
from service outages and maintains campus survivability.
The most critical service that the network provides is telephone because this service must operate 24/7 with five
nines reliability. Therefore, network reconfiguration or
modification requires advance notice to a department, an
entire building or possibly a campus prior to performing
any task. The core network is designed with redundant
paths between campuses. The telephone system uses the
inter-campus optical fiber links for normal extension-toextension traffic. If these links fail, then the PSTN trunks
are used by adding the missing digits. If the PSTN trunks
fail, then local outbound calls are routed to another campus and incoming calls are rerouted to another campus,
upon notification of the local PSTN.
The next most critical service is for the servers that
provide e-mail and network-based applications as well as
other servers in the SAN that are needed for normal operations. The college is moving the MicrosoftВ® My
Documents folder for every administrator and faculty
member from the local PC drive onto the SAN. As a
result, the network is required for PC users to perform
office clerical functions.
In addition, administrative applications are moving
from mainframe-based applications to database servers
that are outsourced. The typical functions of the college,
such as registration, bill payment and grades, are now
using network connections for data access. A loss of network function has the effect of shutting these departments down. Because a network failure would result in
cancellations of class sessions, there are also dedicated
academic servers for use within the college and for students off campus.
The Internet is now being used by the college to provide connectivity to services and content for students
and faculty off campus and in the classroom. Inbound
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and outbound traffic requirements are rising every semester and the need for redundancy and resiliency to maintain access is a must-have feature. Students opting for distance learning environments will further increase
demand for the services.
One of the newer tasks for the network is video distribution. Each campus has two sets of distance learning
equipment that consists of codecs, microphones, speakers
and cameras for providing PTP or point-to-multipoint
distribution. One set on each campus is in a fixed configuration in a distance-learning classroom that allows students to attend a class without traveling to another campus. The other set is portable and can be set up for special events that are broadcasted to other classrooms anywhere in the college. A typical application of this technology is a speaker in the theater who can be viewed
across the college in any classroom.
The network also supports infrastructure automation,
such as the HVAC systems, security cameras, door access
systems and, in the future, paging systems. These operate
continuously and are accessible to authorized users from
anywhere on the network. These applications have shifted the importance of the network from a casual utility to
a mission-critical service that is integrated into every
facet of the college’s operation.
Of the lesser-known functions of the college is participation in natural disasters or health related emergencies.
This requires that the college provide space for evacuated
residents or for emergency operations. To assist in providing services during these events, the network has capacity
and components configured to allow them to be shifted
from academic to emergency services functions.
The evolution of the Suffolk County Community
College network has been accomplished by strict adherence to best practices design and standards, high performance equipment, documentation, and with close
partnerships with cabling companies, equipment manufacturers, and integrators. The abilities of the network
will continue to evolve as the needs of the college change
and as technology moves forward. Keeping up with the
growing network requires networking professionals to
continually enhance their skills and learn about the new
technologies to ensure that today’s decisions will provide
a growth path to the future. .
Richard Johnston, RCDD
Richard Johnston is director of network and telecommunications for Suffolk County Community College
on Long Island, NY. Richard can be reached at
+1 631.451.4190 or
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How to Work with the Authority
Having Jurisdiction
Document, seek permission and have records available.
Inspectors today are burdened with technical
issues and tremendous challenges when inspecting
low voltage cabling. Many jurisdictions do not
require a permit to be pulled by the information
transport systems (ITS) installer and have no idea that a
cabling project is even under way. Invariably, it is when
the inspector, the authority having jurisdiction (AHJ),
comes to inspect a building for the regulated crafts that
they happen to catch problems associated with the ITS
wiring and infrastructure.
Most inspectors have no formal training in high
speed network cabling, especially with regard to what
makes it function and perform. The AHJ is therefore typically not interested if the network runs at its advertised
speed. What does concern the AHJ is placement of
cables through fire rated walls/barriers and code issues
such as grounding and bonding the system. When violations are present, the AHJ is required to take corrective
action. That’s their job. It is important to remember that
the AHJ is a person just like you and me—burdened
with tremendous responsibility and held accountable for
their performance.
What Does “Qualified Person” Mean?
When an AHJ finds a problem with an ITS installation, the first item of interest is the installer’s qualifications, which in itself can be a rather vague proposition.
Some installers may show evidence of training and competence, such as BICSI’s ITS Installer designation, but
this isn’t a code requirement.
The current definition of installer qualifications in
the 2005 National Electrical Code® (NEC®) states, “One who
has skills and knowledge related to the construction and
operation of the electrical equipment and installations and
Advancing Information Transport Systems
has received safety training on the hazards involved.”
Apparently, there is no requirement that the qualified
person is required to have any formal training except for
minimum safety training requirements. Therefore, most
inspectors judge the network cable installer’s qualifications by the workmanship seen on the job. As a result,
some AHJ’s require a written document to substantiate
qualifications if the level of quality is in question or if
the AHJ is not familiar with a new concept or system
recently introduced.
The NECВ® definition of a qualified person does not
currently require documentation of training, but a lot of
inspectors consider it to be common sense to check
someone’s credentials if their qualifications are in question. If you carry a certification or designation, there
should be no questioning that credential. This is why
you attend training and strive to be competent.
Perhaps an improved definition of “qualified person”
would be as follows: “qualifications to be true by
demonstration or evidence.” This would prompt the
AHJ to ask for and verify credentials, which happens
quite often. Therefore, if an installer is trained and is
not performing work correctly, the inspector may or
may not accept his credentials. In fact, most inspectors
will let you know if your “certified installer” is not
doing the job that he or she was trained to do. It is not
unusual for a manufacturer to be called by an AHJ when
the work of a trained installer is in question. In these
cases, the AHJ seeks to correct the problem and ensure
the installer is retrained.
If you acquire formal training, use it. If you have no
formal training and expect to get by without it, your
days on the job could be numbered. If you have formal
training, be prepared to furnish verifiable proof of your
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qualifications to the AHJ if asked. It is also smart to
include your credentials any time you are making submittals to the AHJ.
Who is the AHJ?
The AHJ comes in the form of many different people.
Typical AHJ’s are the city and county electrical and structural inspectors. There are also the state fire marshals and
federal inspectors who inspect health care facilities funded by Medicare or Medicaid. Their authority is never
questioned. Installers should read the fine print in the
local code book detailing exactly who the AHJ may be.
For example, in the definitions section of the current
version of NECВ®, there is a footnote on AHJ that catches
most people by surprise:
The phrase “Authority Having Jurisdiction” is
used in National Fire Protection Association
(NFPA) documents in a broad manner, since
jurisdictions and approval agencies vary, as do
their responsibilities. Where public safety is primary, the AHJ may be a federal, state, local or
other regional department or individual such as
a fire chief, fire marshal, chief of a fire prevention bureau, labor department, health department, building official, electrical inspector, or
others having statutory authority. For insurance
purposes, an insurance inspection department,
rating bureau, or other insurance company representative may be the AHJ. In many circumstances, the property owner or a designated
agent assumes the role of the AHJ; at government installations, the commanding officer or
department official may be the AHJ.
If the person is in charge, you have no choice except
to answer to them. The AHJ is ultimately responsible for
safety of people in the building and if there is ever a
problem, the AHJ is held accountable. It is no wonder
that many inspectors seem difficult and some AHJ’s find
“unqualified” contractors to be annoying.
Strategies for Working with the AHJ
Where you will work with the same inspectors over
multiple projects, it is especially important to create a
comfort zone for the AHJ. Providing AHJ’s with what
they need results in smoother inspections—and lower
costs—on every project. They all want the same thing,
so why not give it to them up front?
Use a pre-approval process. Create or download an AHJ
consideration form, which is basically a “request for consideration” form that details location and time of installation, methods and solutions used for firestop, grounding or other installed components that matter to the
AHJ. Send this along with other submittal documents.
What you might experience is an inspector who respects
your ability to convey your intentions on the work to
the point that they don’t have to inspect. In fact, inspectors are typically shocked by a contractor who even
mentions firestop, much less contacting them about the
subject. This proactive approach usually impresses AHJs.
How NOT to Treat the AHJ
A man in a three-piece suit carrying a briefcase showed up on a large retrofit jobsite where the installer was removing abandoned
cable and installing new network cables. The man had no hardhat and or steel-toed boots. During the wreck-out, the man began
to look over the shoulders of the installers and was inquiring about how the contractor was to seal the fire-rated barriers. He introduced himself as being from the insurance company and performing a risk assessment. He was not in uniform and did not have a
badge, so the installer quickly dismissed him and escorted him from the jobsite without responding to his request for information.
A week later the same insurance man showed up with the state fire marshal, who immediately red-tagged the doors and evacuated
the building on the spot. The insurance man explained to the installer that he had kicked the AHJ off the job a week earlier and that
the contractor should read the definition of AHJ in the NECВ®. The fire marshal went on to explain that once the jobsite met the concerns of the insurance agent, the fire marshal would be back to perform an inspection on behalf of the state. This is not a good
thing—always be courteous and helpful to who at first may be perceived as “stangers” on the jobsite.
Advancing Information Transport Systems
In many cases, after an AHJ inspects your work several
times, their confidence in your work is such that they ask
you to stop seeking permission. They know your work
and your commitment, you become automatically preapproved, and your work becomes one less item for the
busy AHJ to deal with.
Take photos. An organized set of labeled digital photos
with penetrations alphanumerically
identified may result in review over a
cup of coffee rather than having to pull
the ladder out and carry it around the
Mike Tobias
Mike Tobias is CEO of Unique Firestop Products,
a manufacturer of fire-rated barriers for commercial applications in Robertsdale, AL. Mike can be
reached at 877.960.5018 or mtobias@
Label plans. Assign an alphanumeric
identification to each inspection item
and have plans on the table. Once the
first floor is reviewed by the AHJ, a
simple review of the detailed plans
may not require inspection of other
floors with like solutions.
It is important to know who qualifies as the AHJ, if for nothing else to
avoid alienating the person who needs
to approve your project. The AHJ could
be a county inspector or the building
owner’s secretary, so it is important not
to make assumptions about who is on
the jobsite. Most inspectors are in the
field during the day so the best time to
reach them by phone is early morning
hours, such as between 7 to 8 a.m.
The receptionist at the state or local
government office can usually tell you
which official covers your jurisdiction.
Submit pre-approval consideration
forms along with documentation and
submittals. Acquire manufacturer
training and put it to use. Credentials
are a good thing to have, either from
manufacturers or professional associations such as BICSI. Attend as many
courses and classes as you can and
you will soon be accustomed to seeing
the AHJ smile at you and move on to
another jobsite. .
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January/February 2007
The Wi-Fi Path Loss Equation and
Antenna Specifications
Making sense of manufacturer specifications. BY JOE BARDWELL
Wi-Fi is the designation for a relatively broad family
of wireless devices that communicate in accordance
with the standards set by the IEEE 802.11 committee and a variety of working groups. The antenna
that is used with a Wi-Fi radio (e.g., access point, repeater,
mesh router, bridge, or client device) makes a big difference when it comes to the radio’s ability to transmit and
receive. Understanding the choices available and their
strengths and weaknesses requires some background. This
article provides information that can be applied to selection of indoor and outdoor antennas for Wi-Fi systems.
Over the past year, the type of Wi-Fi devices found in
the marketplace has dramatically evolved from the basic
notebook computer used to check e-mail and surf the
Web, to multi-mode cell phones with Wi-Fi wireless VoIP,
wireless security systems and location tracking, backhaul
for radio frequency identification (RFID) product tag
readers, licensed public safety applications, and much
more. As the sophistication and capabilities of the applications and devices that communicate over Wi-Fi networks has increased, so has the need for best practice
designs and equipment specifications. While a consumergrade access point may provide minimal levels of service
for simple e-mail and Web access, only commercial-grade
equipment, coupled with proper RF engineering in the
design, will support the levels of service that will be
required over the course of 2007 and beyond.
The Antenna as Part of a System
A Wi-Fi system design consists of a number of access
points spread across the indoor or outdoor coverage area.
The design of the network determines where the access
points will be installed. Requirements for a correct design
are simple:
1. Transmitters must propagate signal energy that is
powerful enough to propagate throughout the intended coverage area.
2 Receivers must be sensitive enough to recover the data
bits out of the signal energy present in the installation
3. The ratio of signal energy to background noise and
interference must be large enough to allow the receiver
to identify the desired transmission.
Advancing Information Transport Systems
The requirements may be simple, but meeting them
can be complex and confusing. While this article focuses
on the first point, transmitted power, none of these
points can stand completely alone. The power that must
be radiated from a transmitter is required to meet the
sensitivity requirements of the receiver. The signal-tonoise ratio (SNR) is a requirement specified by the radio
manufacturer and is based on the capability of the receiver’s circuitry. In essence, receiver sensitivity and required
SNR may be considered fixed values, varying only from
one model of radio to the next. In addition, the maximum power output of the transmitter may also be considered a fixed value, limited by the manufacturer, often
in compliance with legal requirements.
The variable that remains, and the choice which must
be made by the designer of a wireless network system, is
the antenna to be used by the radio. We will discuss
antenna selection on the basis of the underlying physics
of wave propagation.
Antenna Basics
Selecting one antenna over another is always a matter
of trade-off. The antenna is simply a radiating device that
receives power from the access point and causes that
power to propagate outwards as electromagnetic waves.
An antenna designer can do many things to shape, direct
and focus the propagating signal, but they cannot create
more signal than was input into the antenna by the
access point. In this lies the focus of the tradeoffs in
antenna design. The design is based on the laws of
physics of electromagnetic wave propagation and there is
no free lunch in the physics department.
Data bits are sent from a device’s operating system
software to an 802.11 Wi-Fi chipset. The chipset and supporting circuitry modulates a carrier signal to represent
bits using specific variations of the carrier. This modulated carrier is the electrical signal that is input into an
antenna. The result is the propagation of an electromagnetic field that conveys the data bits in a known series of
There are three basic concepts that are the foundation
for antenna specification:
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mW and dBm Defined
The mW and dBm scales are both
used to represent signal power.
Conversion between the units
involves a scientific calculator, but
there are a number of rules of
thumb that can be easily applied.
To convert from mW to dBm:
Calculate the base 10 logarithm of
the mW value, and multiply the
result by 10.
dBm = log10(dBm) * 10
To convert from dBm to mW:
Divide the dBm value by 10, then
raise 10 to that exponential power.
mW = 10^(dBm/10)
Here are some rules of thumb to
• 100 mW = 20 dBm (power
consistent with commercialgrade access points)
• 1000 mW (1 watt) = 30 dBm
• 30 mW = 15 dBm (power consistent with many notebook
• Adding 3 dBm results in doubling of the mW value (18 dBm
= 60 mW, start with 30 mW =
15 dBm and double the mW
because you added 3 dBm)
• Subtracting 3 dBm results in
halving the mW value (17 dBm =
50 mW, start with 100 mW =
20 dBm and divide mW by 2
because you subtracted 3 dBm)
1. The isotropic radiator.
2. The inverse square law.
3. The decibel unit of measurement (dBm, dB, dBi).
The Isotropic Radiator
To begin considering how antennas work, imagine a single tiny point in the
vacuum of outer space. Imagine that signal energy has somehow been input
into the point without any wires or connections that would distort it and a
resulting electromagnetic field is radiating outward. This field radiates out as a
perfect sphere, with equal power at equal distance from the point, in all directions. This theoretical point source is called an isotropic radiator (from the
Greek isos, meaning “equal” and tropos meaning “turn”). It produces a consistent, equal electromagnetic field in all three-dimensional directions.
The Inverse Square Law
The details of how the power that is applied to the antenna (from the access
point radio’s antenna output) and how the energy ends up being propagated
into space as electromagnetic waves is beyond the scope of this article.
Nonetheless, it is important to realize that signal strength initially drops off
quickly in the area very close to an antenna—roughly one to two wavelengths
or five to 10 in for a 2.4 GHz 802.11b/g transmitter. After that, the expanding
electromagnetic field decreases in strength in accordance with the inverse
square law. This law of electromagnetic wave propagation holds that when the
distance from the antenna doubles, the signal strength drops to 1/4 of its original value. If a measurement is made 20 ft away from an antenna, and another
measurement is made 60 ft away from the antenna, the signal power decreases
by a factor of nine because the distance is three times greater—hence, the signal power is 1/9 of its original value.
Power Represented as Milliwatts or dBm (dB Milliwatts)
RF engineers represent signal power in a variety of ways. Two common representations encountered in 802.11 wireless LAN design are the milliwatt
(mW) and the dBm. These, somewhat like miles-per-hour and kilometers-perhour, both represent identical quantities, simply using different numeric scales.
The mW scale is linear and the dBm scale is logarithmic, as discussed in the
mW and dBm sidebar on the left.
A typical Wi-Fi access point has a maximum transmit power output (TPO)
of 100 mW, which is the same as saying 20 dBm. A typical client device may
only have a 30 mW (14 dBm) power output.
A typical Wi-Fi device may be able to receive signals that have propagated
outwards and fallen from 100 mW to a low power level of 0.000000000316
mW. This is why the dBm scale is helpful. This mW power level is represented
as -95 dBm, where the negative exponent indicates the value is a fraction less
than 1. The term Received Signal Strength Indicator (RSSI) is often used to refer
to this receiver sensitivity value.
It is common to see specifications of transmitter power output represented
as mW, such as 100 mW TPO. However, receiver sensitivity values are always
shown as a logarithmic, dBm value, such as -95 dBm RSSI.
Advancing Information Transport Systems
Figure 2.
Coverage Model Showing Elevation
Plane Signal Power at Various
Angles Measured at a Fixed Distance
Figure 1.
The Rubber Duck with a
Surrounding Electromagnetic Field
The Dipole Antenna
There is no perfect isotropic radiator in the real world.
The simplest antenna is a pair of radiating elements typically encased in plastic or fiberglass called a dipole antenna, or more commonly known as a rubber duck. Early
versions of this antenna were flexible and covered in rubber, hence the nickname. Like a bar magnet with lines of
force circling outwards from the north and south poles,
electromagnetic waves propagate horizontally outwards
from a vertically oriented dipole antenna with very little
signal energy present straight out the top and bottom of
the antenna, shown in Figure 1.
The radiation pattern coming out of a dipole antenna,
following the electromagnetic lines of force, does not radiate in a perfectly spherical pattern. Rather, the sphere is flattened to form a shape that might be described as a doughnut. More correctly, this shape is called a toroidal pattern.
therefore, adds 2.15 dB to the TPO. Therefore, the 18 dBm
transmitter has an effective power of 20.15 dBm. When
TPO and antenna gain are added, the resulting value is
called the Equivalent Isotropic Radiated Power (EIRP.)
Occasionally you may see gain represented as dBd (dB
relative to dipole). The dBd metric tells you how much better, in the real world, the measured antenna is relative to
the simplest possible antenna (the dipole). An antenna
with a 5 dBi gain would be rated with a 2.85 dBd gain
Antenna Gain
Consider a situation in which a transmitter has an 18
dBm TPO. As such, 18 dBm of power is being input into
the dipole antenna. The output power, however, does not
radiate equally in all directions. Consequently, the power
density is not equal in all directions. The 18 dBm has to
go somewhere, and it doesn’t go out equally in all directions, which makes the effective power density on the
horizontal plane (of the vertical antenna) greater than 18
dBm. This is because very little power goes out the ends
of the dipole. The power is concentrated to the sides. This
effect is called antenna gain. It is the degree to which the
signal power is concentrated more in some directions
than in others.
One way to represent gain is as the ratio of the actual
signal power density and that which would be present if
the antenna were a perfect isotropic radiator. This logarithmic ratio is called dB relative to isotropic, dBi.
A simple dipole antenna has a gain of 2.15 dBi and,
January/February 2007
Figure 4.
Dipole Elevation Graph – Detail View
Figure 3.
Typical Dipole Elevation
Pattern Graph
(because 2.15 + 2.85 = 5). Most manufacturers don’t use
dBd metrics because, all other things being equal, the
numbers are smaller than the dBi values used by their
competitors and the marketplace would likely be confused.
Using RF CAD modeling and simulation software, a
coverage model showing signal power was developed for
a vertical 2.15 dBi antenna with a 30 mW TPO. See
Figure 2. The display is a side view, as seen by someone
standing on the ground, looking at the antenna that is
pointing straight up in the middle. This coverage model
represents a distance of left-to-right horizontal distance
of 7500 feet. Signal power measurements for three different angles are shown.
The term elevation plane is used to refer to a side view.
A top-down view is called the azimuth plane. In the elevation graph, red and yellow hues are “hot” (higher power)
and “cooler” (lower power) signal levels are represented
by varying blue hues. Notice in the elevation plane coverage model that the maximum power measured is -85
dBm. At another angle the power is 5 dB less, or -90 dBm,
and another measurement was 10 dB less at -95 dBm.
This relationship between angle and power reduction is
consistent no matter how far away a measurement is
made. A special graph, called an antenna pattern graph, is
provided by manufacturers to show how their antenna
will operate.
The Antenna Pattern Graph
Manufacturers and distributors provide antenna pattern graphs to show the performance of their antennas.
There are two graphs typically presented: the azimuth
graph showing the top-down view and the elevation
graph showing the side view.
Pattern graphs are presented on a polar coordinate
plane marked from 0- to 360-degrees relative to the
antenna (in the middle.) It’s important to confirm exactly how the manufacturer has oriented their antenna for
Advancing Information Transport Systems
measurement. For example, an antenna intended for ceiling mounting is oriented 90-degrees to one that’s intended for wall mounting. Interpreting the azimuth and elevation pattern graphs depends on knowing what was
intended by the manufacturer. A typical mast mount
dipole antenna is assumed to be mounted vertically, with
the base of the antenna towards the bottom.
The elevation pattern graph for a typical dipole is presented in Figure 3. Notice that the circumference is
marked from 0 to 360 degrees and the horizontal line
across the middle is marked from 5 dB to 30 dB, going
from the outside to the center (note that there is no “5”
for the +5 dB gain point to the right of the “0” point.) A
detailed view of the graph’s markings is shown in Figure
4 for clarity.
To understand the meaning of the graph, consider the
angle of elevation. If you are at the same height as the
antenna you receive the maximum signal. Hence, at 0
degrees there is 5 dB of gain. If you are elevated to a
height 40 degrees above the horizontal (320 degrees on
the graph) then the signal has been reduced by 7 dB
(half-way between the 5 and 10 dB marking across the
center of the graph.) When you are directly above the
antenna, the signal is reduced by 27 dB.
Note that the angles do not imply distance, and the
shape of the pattern does not imply some imaginary
three-dimensional shape in space. The signal doesn’t
form a three-dimensional volume with the shape of the
pattern graph. The graph is a tool to determine the
degree of attenuation at a particular angle relative to the
antenna. It is true, from a purely visual perspective, that
the shape of the pattern gives a good indication of where
the signal will be strong or weak, as if it actually were a
three-dimensional volume (e.g., expanded in some directions, shrunk inwards in other directions.) Do not be
confused, though, into thinking that the graph is intended to show you a three-dimensional shape.
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Antenna Beamwidth
The term beamwidth is confusing because it assumes you
know how the “width” part is being measured. Beamwidth
is an angle, measured on an elevation pattern graph that
intersects the pattern at the points where the signal power
has been reduced by 3 dB. Because a 3 dB reduction is
equal to a 50 percent reduction you’ll often hear
beamwidth referred to as half-power beamwidth (HPBW).
If you examine an elevation pattern graph you can
determine the points where the pattern has been reduced
by 3 dB. These are shown as green dots on the 40-degree
Half-Power Beamwidth diagram in Figure 5. The angle
formed between these points (40 degrees in the diagram)
is the HPBW angle.
It is very important to realize that the HPBW angle is
not an absolute barrier, beyond which no signal is transmitted. As can be seen by studying the example, even at
double the HPBW angle, the signal has dropped -7 dB
from the maximum; it has not disappeared completely.
Here is why this is important. Consider a dipole on a
mast, 30 feet in the air. At first thought it might be a
concern that the pattern graph shows what looks like a
dead spot directly below the antenna. It is not dead; it is
just down by greater than roughly 50 dB. Over 30 feet,
the signal reduction through the air (free space path loss)
is roughly 60 dB. The receiver on the ground, directly
Figure 5.
40 Degree Half-Power
underneath the antenna, suffers 50 dB loss from the
antenna’s pattern and the 60 dB loss from the signal
propagation. If the transmitter were operating at 100 mW
(20 dBm) then: 20 dBm – 50 dB – 60 dB = -90 dBm. That
is still enough for a 1 Mbps or 6 Mbps 802.11 connection—enough, but not optimal. As the user walks away
from the point directly underneath the antenna, there is
more path loss but the degree of loss from the pattern of
the antenna diminishes even more quickly so the weaker
coverage area remains very small.
Conclusion: Applying Manufacturer’s
To design an antenna system you first must know the
TPO for your transmitter and the required RSSI for your
receiver. You then calculate the loss across the path
between the two. Now you select antennas with sufficient gain in the appropriate direction to allow the transmitter to reach the receiver at or above the minimum
required signal strength level. The relationship between
these metrics is:
TPO + TransmitterGain – Path Loss + ReceiverGain
=> RequiredRSSI
This is called the Path Loss Equation, and it’s the basis
for any Wi-Fi or other wireless network system. .
Joe Bardwell
Joe Bardwell is chief scientist with Connect802
Corporation, a systems integrator and wireless
network design consulting firm based in California.
Joe can be reached at +1 925.552.0802 or at
Advancing Information Transport Systems
Increasing Power Margin with
High-Performance Optical Fiber
Specify lower loss cable and optical fiber rated for longer
distances than the intended use. BY ANDREW OLIVIERO
Channel Insertion Loss Reduction
Certain network configuration and connection
assumptions were made by IEEE to establish the power
budgets for 10GBASE-SR at 300 m (see Figure 1, column
A). According to the link model, 77 percent of the total
link power penalty of 7.3 dB is caused by CIL (accounting
for 36 percent, at 2.6dB) and by ISI (41 percent, 3.0 dB).
Therefore, improving CIL or ISI power penalties, or both,
is the easiest way to create power margin.
One strategy for reducing CIL directly is to improve
cable attenuation and connection loss. This strategy
involves the use of:
• Small form factor (SFF) connectors (e.g., LC connectors).
• Optical fiber with improved core centering tolerances
to improve core to core alignment:
- Low core/clad concentricity error (< 1.5 mm).
- Tight clad diameter tolerance (125 +/- 1 mm).
Advancing Information Transport Systems
- Tight core diameter tolerance (+/- 2.5 mm).
• Low 850 nm optical fiber attenuation (< 2.3 dB/km).
• A bend-insensitive coating.
• Low 850 nm cable attenuation (< 3.0 dB/km)
Reduce the Inter-Symbol Interference Penalty
In addition to creating power margin by directly
improving CIL, margin can also be created by lowering
ISI power penalties. In fact, the most significant way to
Figure 1
10 Gb/s 850nm Serial Power Penalties
Power Penalty (dB)
In planning for a LAN, data center, or storage area
network, network designers must ensure that the
optical fiber products they specify can provide the
performance and reliability they need. Specifically,
they may want to provide power headroom to increase
their channel insertion loss budgets for such things as
additional connections or higher loss connectors, and to
improve overall reliability. This is especially critical in
850 nm 10 gigabit Ethernet applications, since channel
insertion loss budgets for these systems are lower than
previous applications.
There are two keys to achieving greater power headroom, also known as power margin:
1. Reducing Channel Insertion Loss (CIL). CIL is the endto-end loss resulting from all connections and splices
in the link, plus the attenuation of the cable itself.
2. Reducing Inter-Symbol Interference (ISI) by using a
higher-bandwidth optical fiber. ISI occurs when bits of
data run together due to high differential mode delay
(DMD), causing low bandwidth in the optical fiber.
A) IEEE Standard based
on OM3-300 Fiber
B) Maximize Channel
Insertion Loss using
OM3-550 Fiber
C) Maximize Safety
Margin using OM3-550
Figure 2
If ISI is reduced . . .
Channel Insertion Loss can increase . . .
bandwidth for lasers that launch power in the optical
increase the power margin—and create a higher CIL
fiber’s center. This, along with higher resolution DMD
budget—is to reduce the actual ISI penalty of the link. ISI
measurements, help ensure that the optical fiber cable can
is lowered by lowering DMD and increasing the bandwithstand deviations in laser characteristics over time.
width of an optical fiber for a given link distance.
The “pulse spreading” that causes ISI is a result of
DMD. Multimode optical fiber is so named because it has
High Bandwidth, High Performance
hundreds of light pathways, or modes, in which light can
Interestingly, one can trade the power headroom
travel along the core of the optical fiber. If the speed of
attained by improving the ISI penalty to increasing the
the light in each mode is equal, then all modes arrive at
channel insertion loss, shown in Figure 2.
the transceiver at the same time; in
other words, the optical fiber will
have zero DMD. But imperfections in
optical fiber manufacturing and
design can result in large differences
in modal speed, causing DMD to
increase. If the laser transmits a pulse
into an optical fiber with high DMD,
different parts of the laser pulse will
travel along the optical fiber at different speeds. As a result, some parts
of the pulse may spread into the
adjacent bit slots, causing the system
to fail.
Controlling and minimizing DMD
minimizes the ISI—and therefore
maximizes the bandwidth—of a multimode optical fiber system. Using an
optical fiber with low DMD can dramatically improve system performance while preserving the low cost
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January/February 2007
What to Look for in
Differential Mode
Delay Testing
DMD testing provides such a
clear picture of how individual
mode groups carry light down
the optical fiber, and which
mode groups are causing DMD,
that the standards require optical fiber to be DMD-tested to
ensure adequate bandwidth for
the rated distances for 10 Gb/s
DMD testing involves transmitting short-duration, high-powered laser pulses in small steps
across the entire core of the
optical fiber. Each pulse excites
only a few modes at each step,
and the individual pulse shapes
and arrival times are captured
at the other end of the optical
fiber. The DMD of the optical
fiber is the difference between
the earliest and latest arrival
times of all pulses at all steps.
From this information, adjustments can be made to the
optical fiber manufacturing
process to produce low DMD
(high bandwidth) optical fiber.
With a highly advanced process
By specifying a higher-bandwidth optical fiber, a designer can trade
off bandwidth headroom to increase CIL budgets. For example, many
designers specify use of 850 nm laser-optimized 10 Gb/s multimode
optical fibers (known as OM3 optical fibers) in data centers. If this optical fiber is used at distances shorter than its maximum rating, the ISI
penalty is reduced and the “liberated” power (e.g., bandwidth headroom) can be devoted to increasing the CIL budget. The result is that
designers of data centers or LANs can use “plug and play” connectivity
solutions, and can support the high loss of some of these systems while
supporting bandwidth and reach requirements.
Consider an 850 nm laser optimized multimode, 10 Gb/s cable solution rated to 550 meters under typical conditions. If this optical fiber is
used to shorter distances (e.g., 300 meters), 1.9 dB of power headroom is
created from the extra bandwidth. This can be added to the 2.6 dB of
budgeted CIL to allow a total of 4.5 dB of CIL, shown in Figure 1, column B. This can now be devoted to the higher-loss connections of some
MTP/MPO cassettes that are used with a plug and play design in a data
center or LAN. This level of performance can also be achieved by using a
300 m rated 850 nm laser optimized multimode optical fiber product to
150 meters.
Because network downtime can be very expensive, reliability is a key
requirement for high performance networks. These two strategies provide more power margins to enable greater flexibility in network design
and, ultimately, greater reliability (Figure 1, column C).
First, it is wise to specify lower loss cables and connectors that provide more power margins to enable higher levels of performance.
Second, to provide more power margins to enable higher levels of
performance and reliability, it is wise to specify an optical fiber that is
rated for a longer distance than what it will be used for. When it comes
to demanding 10 gigabit Ethernet optical fiber applications, do not
assume that all products that meet a particular standard are equal. In
fact, it is possible to find higher performing products that exceed the
standards. The most cost-effective solution is OM3 optical fibers that
have been designed and manufactured specifically for laser transmission. These are available in various performance grades, all featuring a
DMD-controlled core that helps ensure 10 Gb/s support with low-cost
850 nm serial applications up to their rated distances. These optical
fibers also support 1 Gb/s operation, and their 50 micron core size couples sufficient power from LED sources to support legacy applications
such as Ethernet, Token Ring, fiber distributed data interface (FDDI),
and Fast Ethernet for virtually all in-building networks and most campus networks. .
for making optical fiber, DMD
testing serves as a powerful
process control tool to main-
Andrew Oliviero
tain a precise refractive index
profile, even to the center
Andrew Oliviero is the senior product manager for optical fiber products at OFS and is located in its headquarters in Norcross, Georgia.
For more information, call 888.342.3743 (USA) or +1 770.798.5555
or email
region of its optical fiber.
Advancing Information Transport Systems
Testing Multimode Optical Fiber:
Importance of Controlling Launch Conditions
Achieving consistent and reproducible loss measurements.
For many years now, installation of multimode
optical fiber networks has been very common for
traditional Ethernet business applications as well as
for military, aerospace and industrial control systems. Multimode optical fiber deployment is an ongoing
trend that will likely continue to grow as many installations bring optical fiber as far as the desk. The relatively
low cost of system components, as well as easy installation and maintenance, are the driving forces behind the
popularity of these networks.
When testing multimode networks, it is important to
take into account certain particularities of multimode
optical fiber by paying attention to critical test parameters and adapting testing techniques when appropriate;
namely, controlling launch conditions to allow for better
testing of the multimode optical fiber’s loss. This article
discusses the inherent properties of multimode optical
fiber and how controlling launch conditions will yield
more reliable test results.
Figure 1. Loosely coupled modes (high-order) are often
attenuated at bends, connections and splices.
Advancing Information Transport Systems
Launch Conditions and the Propagation of Light
To fully understand the importance of launch conditions, it is worthwhile to first review the concept itself.
Launch conditions refer to the distribution of light
that is injected into an optical fiber, impacting transport
capability (bandwidth) as well as loss of an optical fiber
link. When the distribution of light launched into the
optical fiber fills its core completely, the launch conditions and the optical fiber are said to be overfilled. When
a fraction of the optical fiber core is filled with light, it is
considered to be underfilled. Historically, the optimum
level recommended by standards is 70 percent, but this
percentage no longer has any real technical correlation to
modern-day multimode optical fiber systems.
In multimode optical fiber, there are many possible
optical paths for light to travel. These paths are referred
to as modes. All modes are not equal because they have
different propagating characteristics and different sensitivities to external factors, such as bends and splices.
Figure 2. Typical launch conditions from commonly used
light sources.
Launching light near the central axis of the optical
fiber excites the lower-order modes, often called tightly
coupled modes. In the highest-order modes, also called
loosely coupled modes, a significant part of the power is
located close to or even in the cladding, as shown in
Figure 1.
For these very-high-order modes, losses are usually
high, even for a bend radius of a few centimeters. For
graded-index optical fiber with a 50 or 62.5 Вµm core, a
few turns around a mandrel with a radius of 1 to 1.5 cm,
called a mode filter, filters out these higher-loss modes.
When there is an optical fiber-to-fiber connection,
splice or other interface, it is these higher-order modes
that will be attenuated the most. Once in the cladding,
light is coupled out through mode stripping, thus creating the loss.
Light coupled into any specific mode will transfer to
another mode only through what is called mode scrambling, which can be generated by microbends, splices,
connectors and other factors. For additional information
on mode scrambling, please refer to TIA/EIA-455-54B.
When light from an optical source—surface or edgeemitting LED, laser, vertical cavity surface emitting laser
(VCSEL), light from another optical fiber—is coupled into
a multimode optical fiber, the light’s launch conditions
determine which modes will be excited or filled and to
what extent. Refer to Figure 2. The type of light source
used and the way it is coupled into the optical fiber will
have a huge impact on the launch conditions. Generally
speaking, surface-emitting LED sources have a wide angle
and a relatively large emission surface. This means that
the high-order modes will generally be excited or filled.
Laser sources have a narrower emission surface; therefore,
higher-order modes in the optical fiber would not be significantly filled. The laser light will most likely be coupled into a small group of modes, usually close to the
center of the optical fiber. Unless additional launch conditions are used, testing insertion loss with a laser light
source could yield misleading results.
In other words, when an optical fiber is overfilled, it
means that a large portion of the power is launched into
the high-order modes. If loss is measured under this condition, the result will likely be conservative (higher measured loss) compared to that of a test performed with
underfilled launch conditions. On the other hand, if loss
is tested with a restricted or significantly underfilled
launch, the test results will be overly optimistic (very low
loss) and faults may not be identified.
For example, when a connector ferrule is misaligned
and a test is performed with one set of launch conditions, the unit may measure low insertion loss and indi-
cate that the connector has passed the test, while with
different launch conditions, the unit may measure unacceptable power loss. The loss measurement of an optical
fiber plant that includes connectors is therefore highly
dependent on the launch condition of the source that is
used to carry out the test. Best practices recommend the
use of an overfilled source followed by a five-turn mandrel-wrap mode filter (see TIA/EIA-455-34A).
In general, a surface-emitting LED will provide overfilled (or close to overfilled) launch conditions, while
edge-emitting LEDs and VCSELs are more likely to produce slightly restricted launch conditions. Lasers with
multimode pigtails usually produce restricted launch conditions. Testing multimode loss with sources that have
unknown launch conditions will yield very unreliable and
unrepeatable results that can very often be too optimistic.
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Coupled Power Ratio
Fiber Size
An easy way to characterize the launch condition of a
source is to measure the coupled power ratio (CPR). CPR
is the ratio of the total power out of a multimode optical
fiber to the power measured when a singlemode optical
fiber is coupled into the multimode optical fiber. The
CPR is often used to evaluate the launch conditions of
transmitters and light sources into multimode optical
fibers and is used in TIA/EIA-526-14-A for establishing
attenuation measurement criteria for installed optical
fiber plants.
A higher CPR means that there is high loss when coupled into the singlemode optical fiber and indicates a
more fully filled launch, whereas a low CPR indicates
restricted launch conditions corresponding to an underfilled optical fiber.
When measuring CPR, it is important to use singlemode optical fibers at 850 and 1300 nm because these
optical fibers have a mode-field diameter of approximately 9 Вµm at 1300 nm and 5 Вµm at 850 nm.
As shown in Tables 1 and 2, the TIA/EIA-526-14-A
standard has identified five categories for 50 Вµm and 62.5
Вµm optical fiber at 850 nm and 1300 nm. For detailed
information on the five categories and on CPR measurement procedures, refer to TIA/EIA-526-14-A.
The CPR will affect loss measurements differently,
depending on the type of light source and filter used.
With a category 5 source, which is very underfilled, the
loss results will be highly optimistic—the link will seem
to have very low loss. With a category 1 source, which is
overfilled, the results will be conservative.
Measuring Under Controlled Launch Conditions
To ensure optimum multimode loss measurements,
some multimode test and measurement devices control
launch conditions to provide consistent and reproducible
loss measurements.
For devices used to test both 50 Ојm and 62.5 Ојm core
optical fiber, when testing 50 Ојm optical fiber, use of a
mode filter, consisting of five-turns mandrel with a diameter of 25 mm at the output of the device, is recommended for accuracy.
What does that mean in day-to-day tests? As an example, suppose a test is performed on a 50 Ојm optical fiber,
with two connections, using two different types of test
equipment. The reference source is a LED at 850 nm with
optimum launch conditions (CPR category 1 for 50 Ојm)
with an external mode filter applied to the launch optical
fiber output. After the LED source has been referenced on
a power meter, the loss measured on the optical fiber
under test is 0.5 dB (optical fiber loss and connectors
included). The same optical fiber is now tested with an
Advancing Information Transport Systems
Categories Categories
1 to 3
4 and 5
Table 1. Light source CPR values
(in dB) for 850 nm.
Fiber Size
Categories Categories
1 to 3
4 and 5
Table 2. Light source CPR values
(in dB) for 1300 nm.
underfilled 850 nm FP laser source referenced on the
same power meter, now showing a loss of 0.2 dB. If the
pass/fail threshold for this cable was set at 0.4 dB, the
testing device would pass for the FP laser source but fail
for the LED.
In this example, measurements using two different
instruments with different launch conditions produce
random loss readings—sometimes right on target and
sometimes too optimistic. This is not surprising, especially when using laser sources such as Fabry-Perot or VCSEL;
when lasers are used in sources, they usually produce
underfilled conditions.
Launch conditions for test equipment varies, even
from a single test equipment manufacturer. Testing without knowing the launch conditions can result in getting
a passing result when in reality the circuit should be
failed, as when there is a misaligned connector. This
could also lead a technician to misinterpret instrument
results, try another test from another instrument, and
extend the time and cost of the project.
As a general rule, it is always best to specify launch
conditions. Military, aerospace and industrial applications
will most likely require category 1 or category 2 testing,
as there is no room for failure. Category 1 to category 3
testing may be fine for less critical or less cost-sensitive
applications. In all cases, category 4 to 5 testing should
be avoided to obtain reliable measurements. .
Michel Lebanc
Mario Simard
Michel Leblanc is senior technical
advisor and Mario Simard is product manager for EXFO, a manufacturer of test and measurement
equipment headquartered in
Quebec, Canada. For more information, contact Mario at or at
+1 418.683.0913, ext. 3129.
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Designing Telecommunications Distribution
Systems—is for you.
Since this training course was last revised in 2003,
a lot has changed in the design of distribution systems. This is why the new DD102 offers important
training for any information transport systems
(ITS) professional.
In the new DD102, over 40 percent of the content
has changed; over 90 percent of the images have
been revised, too. The intensive, six-day course
still focuses on the fundamentals of designing a
structured cabling system. However, you will find
some new features that improve your learning
experience, including the following:
• Twelve structured exercises reflecting real world
conditions that build upon each other during
the week
• Updated final exercise that takes you through
responding to quote request and bidding
the project
• New student guide that closely follows the
class, contains review questions, and contains
chapter and page references to the
Telecommunications Distribution Methods
Manual (TDMM).
DD102 topics include:
• Codes, standards and regulations
• Principles of transmission
• Electromagnetic compatibility
• Telecommunications spaces
• Work areas
• Horizontal distribution
• Backbone distribution
• Grounding, bonding and electrical protection
• Firestopping
• Telecommunications administration
• Design, construction and project management
• Networking fundamentals, including VoIP
and wireless
• CO-OSP and campus cabling
For more information or to register for DD102, call
+1 813.979.1991 or 800.242.7405 (USA and
Canada toll-free) or visit
As a first step in the redesign of the BICSI Web site, a new
graphic template has been introduced that better reflects
BICSI’s colors and logo. The next steps in the coming
months include improving navigation to make it easier to
find information as well as new content so that members
can obtain up-to-date, complete information on products
and services. See for yourself by visiting
BICSI Conference Schedule
2007 Canada Conference
March 4-7, Vancouver, British
Columbia, Canada
2007 Spring Conference
April 15-18, Dallas, Texas
2007 South Pacific
March 26-28, Sydney, Australia
2007 European
June 18-20,
Dublin, Ireland
2007 Middle East &
Africa Conference
April 1-3, Dubai, UAE
2007 Fall Conference
September 10-13, Las Vegas,
January/February 2007
Manual Reflects
Outside Plant
You will notice a
slight difference in the
title for BICSI’s new 4th
edition outside plant
(OSP) manual, to be
published during the
first quarter of 2007:
Outside Plant Design
Reference Manual (OSPDRM). This new edition, formerly known as the Customer-Owned Outside Plant (COOSP) Design Manual, now reflects the broad application
of design and construction issues for OSP owned by customers or service providers. BICSI’s Technical
Information and Methods (TI&M) Committee and Board
of Directors agree that changing the name for this latest
edition invites a broader readership.
The fourth edition of the OSPDRM will be unique in
many ways. As with other recent manuals, the OSPDRM
will address global best practices, supported by relevant
codes and standards at the end of each chapter. Content
changes include an important chapter on legal considerations that discusses some of the issues and problems
that are common on OSP projects; updated information
on cost estimating; grounding, bonding and protection;
cable types; and design considerations for overbuilds.
To order your OSPDRM, call +1 813.979.1991 or
800.242.7405 (USA and Canada toll-free) or visit
U.S. Northeast Region Meeting
March 1, 2007 Corporate Complex
Allentown, Pennsylvania
US Western/South-Central Region Meeting
March 13, 2007
Venue TBD, Phoenix, Arizona
U.S. Southeast Region Meeting
March 22, 2007
OFS Factory, Atlanta, Georgia
U.S. Northeast/North-Central Region Meeting
May 16, 2007
Charleston Civic Center
Charleston, West Virginia
U.S. Southeast Region Meeting
June 28, 2007
Venue TBD, Charlotte, North Carolina
U.S. Northeast Region Meeting
July 23, 2007
Venue TBD, Harrisburg, Pennsylvania
U.S. Western Region Meeting
July 24, 2007
Honolulu Community College, Honolulu, Hawaii
U.S. Northeast Region Meeting
October 18, 2007
CXtec Facility, Syracuse, New York
U.S. Southeast Region Meeting
October 18, 2007
Venue TBD, Jacksonville, Florida
Advancing Information Transport Systems
BICSI Courses
For more information about courses, please contact BICSI at +1 800.242.7405 (USA/Canada toll free)
or +1 813.979.1991 or visit
February 2007
Designing Telecommunications Distribution Systems,
Telecommunications Distribution Design Review,
ITS Installer 1 Training, Indianapolis, IN
ITS Installer 1 Training, Tampa, FL
ITS Installer 2 Training, Tampa, FL
Designing Telecommunications Distribution Systems, Tampa, FL
Introduction to Voice/Data Cabling Systems, Phoenix, AZ
Telecommunications Distribution Design Review, Tampa, FL
ITS Installer 2 Training, Providence, RI
Indianapolis, IN
Indianapolis, IN
Site Survey and Media Selection, Phoenix, AZ
ITS Technician Training, Providence, RI
Designing Telecommunications Distribution Systems,
Introduction to Voice/Data Cabling Systems,
Introduction to Wireless, Allentown, PA
Telecommunications Distribution Design Review, Vancouver, BC
Vancouver, BC
Allentown, PA
March 2007
ITS Installer 1 Training, Tampa, FL
Introduction to Networks, Vancouver, BC
Introduction to Voice/Data Cabling Systems, Vancouver, BC
Telecommunications Distribution Design Review, Columbus, OH
ITS Installer 2 Training, Columbus, OH
ITS Installer 2 Training, Tampa, FL
Introduction to Voice/Data Cabling Systems, Tulsa, OK
ITS Installer 1 Training, Tulsa, OK
ITS Technician Training, Tampa, FL
Designing Wireless Networks, Tulsa, OK
Telecommunications Distribution Design Review, Tulsa, OK
Designing Telecommunications Distribution Systems, Tampa, FL
Telecommunications Distribution Design Review, Tampa, FL
DD = Distribution Design
DA = Data Distribution Design
TE = Cabling Installation
WD= Wireless Design
OSP= Outside Plant Design
January/February 2007
BICSI Courses
BICSI World Headquarters
For more information about courses, please contact BICSI at +1 800.242.7405 (USA/Canada toll free)
or +1 813.979.1991 or visit
8610 Hidden River Parkway,
Tampa, FL 33637-1000 USA
+1 813.979.1991 or 800.242.7405
(USA & Canada toll-free); Fax: +1 813.971.4311;
Web site:; E-mail:
April 2007
ITS Installer 1 Training, Tampa, FL
Designing Networks, Dallas, TX
Cable Plant Design, Dallas, TX
Designing Telecommunications Distribution Systems, Dallas, TX
ITS Installer 1 Training, Dallas, TX
Designing Wireless Networks, Dallas, TX
Telecommunications Distribution Design Review, Dallas, TX
Network Design Specialty Review, Dallas, TX
Wireless Design Specialty Review, Dallas, TX
Optical Fiber Installation Theory and Technique, Dallas, TX
Testing, Certifying and Troubleshooting Copper and Fiber,
Dallas, TX
BICSI Executive Staff
Executive Director
David C. Cranmer, RCDD,
Professional Development and Credentialing Director
Richard E. Dunfee,
Director of Administration and Chief Financial Officer
Betty M. Eckebrecht, CPA,
Conferences and Meetings Director
Georgette Palmer Smith, CMM,
Director of International Operations
Jan Lewis,
ITS Installer 2 Training, Dallas, TX
ITS Technician Training, Tampa, FL
Introduction to Networks, Dallas, TX
BICSI News Staff
Introduction to Voice/Data Cabling Systems, Dallas, TX
Introduction to Customer Owned Outside Plant, Dallas, TX
Michael McCahey,
Introduction to Wireless, Dallas, TX
Grounding and Protection Fundamentals for
Fiber Optic Network Design, Dallas, TX
Designing Telecommunications Distribution Systems, Tampa, FL
Telecommunications Distribution Design Review, Tampa, FL
ITS Installer 2 Training, Tampa, FL
ITS Technician Training, Dallas, TX
Telecommunications Systems, Dallas, TX
DD = Distribution Design
DA = Data Distribution Design
TE = Cabling Installation
Publication Coordinator/Designer
Wendy Hummel,
Copy Editor
Clarke Hammersley,
Copy Editor
Joan Hersh,
BICSI International Staff
European Office Supervisor: Laura La Porta
+32 2 789 2333,
WD= Wireless Design
OSP= Outside Plant Design
Japan District Manager : Kazuo Kato
+81 3 3595 1451;
Mexico Office Representative: Gilberto Ferreira Ruiz, RCDD
+52 55 5638 1228;
South Pacific Office Manager: James Armytage
+ 61 3 9813 3355;
The BICSI News is published bimonthly for BICSI, Inc., and distributed to BICSI
members and BICSI Registered ITS Installer 1, ITS Installer 2, ITS Technicians; and
Residential Installers. Articles of a generic nature are accepted for publication; however, BICSI reserves the right to edit these for space or other considerations. Opinions
expressed in articles in this newsletter are those of the writers and not necessarily of
their companies or BICSI. В© Copyright BICSI, 2007. All rights reserved.
BICSI and RCDD are registered trademarks of BICSI, Inc. Printed in the USA.
Advancing Information Transport Systems
Standards Report
TSB-155 Approved
The development process was
long and tedious but TSB-155 has
finally been approved. And now
we wait for ANSI/TIA/EIA-568B.2-10, but why do we need
Donna Ballast,
568B.2-1 Transmission Performance
Specifications for 4-pair 100 ohm
Category 6 Cabling was published.
This standard characterized category 6 cabling from 1
MHz to 250 MHz.
When IEEE 802.3an group began their work, they
asked for additional bandwidth characterization of the
installed base. The group’s original goal was 625 MHz
over some length of category 5e and 100 meters of category 6. TIA agreed to do the work and a new demon was
identified—alien crosstalk.
In June 2006, the IEEE 802.3an 10-gigabit Ethernet
(10GBase-T) standard was approved. This standard established physical coding and sublayer interface for 10GBase-T
applications over balanced twisted-pair copper cabling
systems. It also established signaling and interference
requirements for semiconductor chips that will support
10Gb/s performance and specified four connector channel electrical requirements for augmented category
6/Class EA, class F, and category 6/class E cabling systems
(over the frequency range from 1 MHz to 500 MHz).
In December 2006, TSB-155 Guidelines for the
Assessment of Category 6 Cabling in Support of 10-Gigabit
Applications was approved for publication. These guidlines
provide a means to determine if a category 6 permanent
link or channel meets the requirements of ANSI/TIA/EIA568-B.2-1 from 250 MHz to 500 MHz and is sufficiently
immune to alien crosstalk.
Logically, any noise from outside the victim (or disturbed) cable would be alien crosstalk, but TIA defines
alien crosstalk as “unwanted signal coupling from a disturbing pair of a four pair channel, permanent link, or component
to a disturbed pair of another four pair channel, permanent
link, or component.”
In TSB 155, alien crosstalk is specifically “crosstalk coupling between four pair category 6 cabling in close proximity”
to the victim cable. Why? Anything else would be much
more difficult, if not impossible, to field test.
Depending on the alien crosstalk environment,
10GBase-T should operate over channel lengths between
37 and 55 meters of category 6 cabling. At less than 37
meters, alien crosstalk should not be a problem but that
can only be verified by testing.
According to TSB 155, field test equipment used for
assessment of category 6 cabling to TSB-155 guidelines
should meet the accuracy requirements for level IIIe field
testers in ANSI/TIA/EIA-568-B.2-10 Annex I.
So what if you test the category 6 channel and it is
longer or doesn’t measure up? Mitigation procedures are
also provided.
If the failure is anything other than alien crosstalk,
there is the list of options in TSB 155 Annex B from
January/February 2007
Standards Report-continued
which to choose, one by one, retesting after each until
the channel passes:
Option 1—Replace the work area, patch, and/or equipment
cords with category 6A cords.
Option 2—Reconfigure the cross-connect as an interconnect.
Option 3—Replace the consolidation point connector with a
category 6A consolidation point connector.
Option 4—Replace the work area outlet connector with a
category 6A work area outlet connector.
Option 5—Replace the cross-connect or interconnect with a
category 6A cross-connect or interconnect.
Then there is Option 6, which is implied but not on
the list—replace the horizontal cable with category 6A.
If the failure reported is alien crosstalk, there is another list in TSB 155 Annex C to follow, again retesting after
each until the channel passes:
1. When selective deployments of 10GBASE-T applications
are possible, utilize non-adjacent patch panel positions
(patch panel adjacency should also be checked at the rear
of the patch panel), separate the equipment cords and
unbundle the horizontal cables.
2. When deploying 10GBASE-T applications in adjacent
patch panel positions, in the telecommunications room,
testing is recommended; the number of disturbed channels
to be tested should be determined using statistical sampling
techniques based upon the intended confidence level.
a. Identify measured patch panel positions to be
included in the power sum.
b. Select and test those channels with connectors
adjacent to, or cable segments in the same bundle
as, the disturbed channel. For these channels, test
the alien crosstalk to be included in the power sum
calculation following the procedures in clause A.9.
mitigate the alien crosstalk coupling such as category 6 ScTP and category 6A.
c. Reconfigure the cross-connect as an interconnect.
d. Replace connectors with category 6A.
e. Replace the horizontal cable with category 6A.
A Few Noteworthy Points
TSB 155 clause A.9 does not exist. ANSI/TIA/EIA-568B.2-10 is currently still in committee and, according to
industry sources, publication is not likely until late 2007
or early 2008. No TIA standard exists that specifies transmission requirements for category 6A cabling. Nor does
“Annex I,” which specifies accuracy requirements for
level IIIe field testers. Until ANSI/TIA/EIA-568-B.2-10 is
actually published, those requirements currently in the
drafts are not fixed.
What may seem to be small changes in wording can
have a huge impact on your bottom line. For example,
ANSI/TIA/EIA-568-B.2-10 Draft 5 allows for “normalization” of power sum attenuation to alien crosstalk ratio
far-end (PSAACRF).
PSAACRF is a “computation of the unwanted signal coupling between cabling or components in close proximity from
multiple disturbing pairs at the near end into a disturbed pair
at the far end, and relative to the received signal level in the
disturbed pair at the far-end.”
However, there are dissenters within the TIA TR42
committee who want to delete PSAACRF normalization.
Small change?
Big surprise?
Remember, the sole purpose for developing category
6A cabling was to support 10GBase-T applications over
100-meter UTP channels. Remove PSAACRF normalization from the current specifications (ANSI/TIA/EIA-568B.2-10 Draft 5) and UTP cabling would NOT routinely
pass category 6A field testing, even though the links and
channels would support all 10GBase-T applications.
However, shielded cabling systems would pass without
PSAACRF normalization.
Contractors Beware!
3. In the event that the alien crosstalk transmission parameters given in either 6.1 or 6.2 are not met in step 2, the
alien crosstalk may be mitigated by the following procedure:
a. Reduce the alien crosstalk coupling by separating
the equipment cords and the patch cords and unbundling the horizontal cabling.
b. An alternative to separating equipment cords is to
utilize equipment cords sufficiently specified to
Advancing Information Transport Systems
UTP copper cabling is not the only media choice that
supports 10GBase-T. ScTP category 6, which meets the
requirements of ANSI/TIA/EIA-568-B.2-1 from 250 MHz
to 500 MHz and Class F cabling systems, also supports
10GBase-T applications.
If you are bidding on design and installation projects for
category 6A cabling, make certain that a fixed set of cabling
requirements is part of your contract documents, and not
just a reference to a document that is still evolving. .
Jack be Nimble
Jack be Quick
Pick your category. Choose your colors.
Decide on straight or angled. Click the cap
for quick change. One jack does it all.
Our jacks are specifically engineered
to give you flexible options. They’re easy
to install. And save you time.
We help you make
great connections.в„ў
В©2006 CommScope, Inc.
All Rights Reserved.All trademarks identified
by В® or TM are registered trademarks or
trademarks, respectively, of CommScope.
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