Oscilloscopes to high-end analyzers–those are the solutions that the
T&M industry spans. The products would include spectrum analyzers, network
analyzers, protocol analyzers, logic analyzers, oscilloscopes, and handheld
testers. In the communications sector, these products are used in the wireless
networks, the wired networks, and the LAN/WAN environments. These products also
find significant use in the broadcast and in educational institutes, and
software houses. The last two especially use these products for the R&D in
communications.
Technology Options
This is one sector that has to be always ahead of the emerging technology
trends. Be it in the semiconductor or the manufacturing or the service provider
segment, T&M products have to be ahead or on par with the emerging industry
standards, as they have to facilitate the deployments. Take for example
wireless: Everyone knows that 3G is in trials or is getting deployed in some
places. Now for the deployment of the 3G networks, the service providers will
look for the latest test equipment from the T&M vendors to allow them to
define and manage their networks. Similarly, the 3G phone makers would require
test equipment in their manufacturing processes. So players like Agilent,
Acterna, and Tekronix have products that facilitate the services and
manufacturing. The products that would be used in communications sectors like
the testers, simulators, and analyzers have to be in consonance with the latest
developments in ATM, bit-error-rate, cable (metal and optical), DSL, Frame
Relay, ISDN, modems, MPEG, SDH/PDH/SONET, voice over packet, RF/microwave, and
optical, among other things.
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n Analyzers: Spectrum
analyzers and network analyzers have been the next common general-purpose test
and measurement instruments after oscilloscopes. The spectrum analyzer sketches
a signal in the frequency domain like an oscilloscope, which sketches a signal
in the time domain. Spectrum analyzers plot the voltage for each frequency
component of the signal. An oscilloscope plots instantaneous voltage of a signal
versus time. Spectrum analyzers can measure frequency, power, harmonic content,
modulation, spurious, and noise. But it is being transformed as an
application-specific tester. Most of the Spectrum Analyzers required are below
4GHz.
Network analyzers are used to watch a wide variety of devices, from
components and materials to circuits, equipment, assemblies, and systems. It
measures the transmission and reflection characteristics of linear circuit
networks. There are two main types of network analyzers–scalar and vector. The
scalar network analyzers measure only the amplitude portion of the S-parameters
resulting in measurements such as transmission gain and loss, return loss, and
standing wave ratios (SWR). Vector network analyzer measures and also shows the
complete amplitude and phase characteristics of an electrical network. The shift
is in favor of vector network analyzers.
n Newer
Solutions: Advances in communications technologies have led to test
equipment that can evaluate new emerging standards. So there has been
upgradation in the modulation and demodulation techniques is areas like GSM and
CDMA. These features have been incorporated in signal analyzers too. Need for
greater capacity and faster throughput has let to creation of different testing
parameters. For example, vendors are today prepared to test 80 gigs too.
n Change, the
Only Common Factor: Take a basic time-domain tool like an oscilloscope. For
today’s mixed signal applications the engineers require mixed signal
oscilloscopes to view and trouble shoot analog and digital parts of the circuit
simultaneously.
Today, spectrum analyzers are no longer simple frequency domain instruments.
They come with application personalities to solve the format specific
measurement problems like GSM, CDMA, and 3G. A data tool like logic analyzer has
to provide deeper insight and solve the signal integrity problems through
higher-level abstraction of data.
n A Management
Solution: In the last couple of years, T&M has moved from being a
hardware product to a software solution. Today, it is more about a management
solution.
Buying Tips
n Compliance
with Standards: One of the most important things to consider is to look if
the products are compliant with the specifications laid out by standards
organizations like ITU, ISO, ETSI, and ANSI. This is because the results of
using the solution have to be effective and accurate.
n Portability
and Ruggedness: This is a very important consideration, as the instruments
need to be easily accessible and should be capable of sustaining various
environmental conditions, particularly if the units are used in field.
Test Instrument Categories |
Network test instruments are divided into two basic categories: Physical Physical Layer Analyzers: On the physical layer Higher Protocol Layer Analyzers: On the higher protocol layer Application performance is measured using software agents that simulate |
n Scalability:
The solution has to be scalable, as it has to meet up with the evolving
technologies. The solution should allow the upgrades to happen easily through
software management. Scalability has to be in newer and deeper measurement
through software.
n Niche
Solutions: Going for general-purpose instruments, which do not address the
specific sector, could be a bad investment. This approach will allow conduct of
the tests that are necessary.
n Product
Roadmap and Support: This should be a consideration, as it will allow one to
go for a scalable solution and prevent from having an obsolescent product. As
vendors phase out products, the support would become important so that the
network would not suffer. Also, going for vendors who provide good pre-sales and
post-sales support along with the local technical and applications support can
help the solution to be finely tuned at all times. And can help one to look at a
good migratory path.
Market Information
n Promising
Market: The market for T&M has been active and promising. The total
market is estimated to be about Rs 250-275 crore by March this year. It is not
just the communications sector that has been attractive, the broadcast and
education markets too have been aggressive. Moreover, there has been sale to the
defense and PSUs too.
n Telco
Ramp-up: Traditionally, BSNL and MTNL were the big buyers. But others are
moving in fast. There has been increased activity in the private sector both on
the GSM and CDMA front. The two largest corporate houses in India, Tata and
Reliance, rolled out their services. Others like Bharti, BSNL, and Hutch have
consolidated and announced new launches. Overall, telecom services, be it the
basic, cellular, broadband, DLD, or ILD, are growing. Market estimates suggest
that Reliance must be investing about $15—20 million on test, monitoring, and
management. Bharti’s investment is estimated to be about $5 million and that
of Tatas around $3 million.
n QoS Drive: The
focus of operators is and will be on customer acquisition and high-definition
services. This means each of them is using the latest in technology like SDH or
SDH over DWDM or DWDM or TDMA/IP or CDMA 2000 1X or GPRS. The investment is
coming in T&M to support quality networks, network operating centres, and
central processing offices. Service providers are realizing that they cannot
perform without T&M solutions.
n Defense,
Broadcast Big Buyers: Besides the communications sector, the broadcast and
education markets have been aggressive. Moreover, there have been sales to the
defense and other PSUs too. The easing of US sanctions since October 2001 has
enabled several global players like Agilent, Acterna, and Tektronix to sell
their products all around. During the sanctions, they were not able to sell even
oscilloscopes with 1G sample/second performance. Today, they can even sell to
agencies like Aeronautical Development Establishment, the Electronics and Radar
Development Establishment, Bharat Electronics, HAL, DRDO, ISRO, among other
entities. The licenses to supply get cleared in four-six weeks time.
n Solutions,
not Just Boxes: Most of the large vendors today talk of a solution. Even
oscilloscopes are being sold with solutions built around them. The solutions
approach will stay as the service providers would be looking at network
monitoring, QoS for various networks–be it the data, optical, mobile,
satellite, or cable TV–and fraud/churn management as some of the main ways to
bring about service differentiation. T&M business is changing from
tender-basis to rational investment procurement decision. However, it will take
time before T&M will be seen as a tool for justifying the return on
investment.
n Big Vendors
Rule: Most of the leading vendors like Agilent, Acterna, and Tektronix have
made significant wins. Some of the large orders that were finalized last year
were that of MTNL for 24 OTDR-Type B, 9 SDH analyzers STM 1/4 and SDH analyzers
STM1/4/16; BSNL tender for 175 mini OTDRs, 20 WDM analyzers, 38 OTDRs. These
orders were close to Rs 70 crore. This year the investment on OTDRs has been
slightly less considering the fact that most of the fiber backbone has already
been built. During the globally downturn period, in the past couple of years
too, the T&M vendors grew on an average of 10—12 percent. But this year,
they could be seeing close to 20—25 percent growth.
While Agilent Technologies has complete portfolio of solutions for all types
of telecom providers assisting through design, network optimization, technology
migration, and implementation from spectrum analyzers to network analyzers to
antenna testing, Tektronix is very strong in protocol analyzers, besides other
products. It is believed that Tektronix has close to 85 percent market share in
this arena. Acterna is strong in the OTDR and DWDM analyzers and has solutions
covering optical transport, cable, wireless, data IP, and access network.
Others like ICT, Fastech, Anirtsu, Seven Hills, Aishwarya Telecom, and
Trinity Electronics have also made significant inroads into BSNL/MTNL market.
ICT Electronics/Trend addressing PDH, SDH, and SONET technologies got orders for
SDH analyzers and also on the access side, supplied test solutions for ATM,
ISDN, DSL, etc. Fastech, which distributes, Sunrise Telecom’s solutions, is
strong on the handheld side. On the RF side, Anirtsu too has some good
successes. Other majors like Sunrise, Nettest, and Fluke are present through
distributors. Some of the big-time distributors include AIMIL, Aplab, Fastech,
Forbes Gokak, Meera Agencies, Scientific Mes-Tek, VXL, etc. In the BSNL tenders,
ITI has also supplied SDH/PDH products.
n Future
Perfect: With the telecom horizon becoming distinct, the belief is that the
likes of Bharti, Tata, Reliance, and Hutchison, and those like GAIL and Power
Grid are all there for future. It is not possible for them to roll out services
without the T&M vendors. And probably, the service providers will focus on
their core business and leave the measurement and management operations to the
T&M companies. Further, though the telecom operators may be looking for
business within the country, in future they may looking at other opportunities
like looking at handling outsourced back-end operations. One of the most
significant things to happen to the T&M industry, besides the telecom growth
is the joint T&M solution development. All the major vendors, be it the
Agilent, Tektronix, or National Instruments, have software development centres
in India and are working with other global development centres globally. India
could become the test bed.
T&M for Mobile SPs
n QoS: The
Focus: No one is questioning the merits of good service quality. But the
question is the technical pressures. Standards are evolving and hardware
capabilities are advancing. Hardware and software compatibility issues are
becoming more difficult to handle as new technology comes. Today, QoS is more
than guaranteed bandwidth, a clear and continuous signal, and reliable roaming
access. It has been observed that mobile users will use their phones more often,
and stay on the phone up to 20 percent longer, when their calls are not hampered
by noise, echoes, or other interruptions.
n Networks: Problems
with voice transmissions are easy to hear and are very distracting to the
parties on either end of the conversation. The subscriber doesn’t know about
base stations and protocols, he is interested in voice quality. So voice quality
is a major point of emphasis for network quality efforts. Several methodologies
are accepted for managing voice quality in the network like drive tests,
in-service non-intrusive measurement devices (INMD), traffic generation and
analysis.
n Marketing: Marketing
usually has no direct technical responsibility for implementing or enforcing QoS
programs. However, QoS data informs the marketing activity, which in turn
produces meaningful analysis of market trends and subscriber needs. In a
well-run network business, marketing has ready access to the reports and logs
that come out of the QoS monitoring process. Ultimately, marketing relies on
many of the same tools the other departments use to monitor, detect, and
troubleshoot QoS-related issues. The key here is to integrate these tools,
already in place for operations and engineering activities, into the marketing
process such that the data is always current and easily available.
n Security and
Billing: The security and billing activities involves tracking network usage
and the attendant revenues. Both rely on similar processes and tools. The
security activity is chartered with minimizing fraud losses and preventing
illicit network use. The billing group is interested in maximizing revenue from
every legitimate call connection and network signaling transaction.
Many different fraud scenarios are common in today’s mobile network
industry. They range from the opportunistic subscriber who sees a chance to make
a ‘free’ call, to the calculating, systematic usurper of network
services.
Roaming fraud: This is the recourse of the subscriber who concludes
that he or she can get away with making costly international calls for free. It
often succeeds because of the normal 48-hour time span required to exchange
transferred account procedure (TAP) files between networks. By the time the
fraud is detected, the subscriber may be out of reach.
Excessive calls (amount): This type of abuse is characterized by an
‘inappropriate’ number of conversations or call attempts to a risky
destination. This destination may be one that has had problems in the past.
Similarly, there may be an excessive number of calls from a subscriber who is on
a risk list.
Excessive calls (duration): This term refers to the accumulated
duration of calls from a risk-listed subscriber, or to a risky destination. It
also includes the duration of single calls.
SIM Cloning: This is in effect counterfeiting a subscriber’s
identity. It is possible to purchase equipment that can duplicate SIMs, then
program the cloned SIM into a second, or third mobile phone. This phone is used
at the original subscriber’s expense until detected.
Black list: This denotes calls from individuals whose subscription to
the network has been withheld for some reason (possibly for participating in one
of the fraud schemes listed above).
Resolving Interference Nightmare
If one is investigating reports of dropped calls, noisy connections, lost
channels, and poor reception in one of the base station coverage areas, the
equipment at the station checks these. However, something is still corrupting
the communication channels. These could be creation of signals that accidentally
or intentionally interfere with wireless RF signals.
n Interference
Causes:
Improperly Configured Transmitter: Operator X is transmitting on operator Y’s
frequency unknowingly due to a fault or an incorrect setting; and the operator
of the transmitter would be happy to correct it to restore his own service
level. Interference in mobile equipment poses some problems other than that in
base station testing. While most of the same techniques used at the BTS can be
used in the field, there are some limitations. For example, it is not as easy to
disable a channel to clear out intended signals. Most interference is relatively
localized, so the mobiles will have acceptable call quality everywhere except in
the trouble area
Unauthorized Transmitter: Operator X is transmitting on operator Y’s
frequency intentionally in the same frequency band.
Cell Overlap: A cell from network exceeds specified coverage in one or
more channels. Incorrect antenna tilt, excess transmitter power, or a change in
the environment can cause overlap.
Intermodulation from Another Transmitter: Intermodulation interference
can be the result of one or more external radio signals getting into the antenna
feeder coax and entering the offending transmitter’s nonlinear final amplifier
stage. The external signals mix with each other and with the transmitter’s own
signal, creating intermodulation products that appear as "new" (and
often very undesirable) frequency components in the communications band.
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Intermodulation in a Rusty Fence, Roof: The intermodulation effects from
physical structures such as the rust between the individual roof sections are
difficult to locate.
Intermodulation in Antennas or Connectors: Minor corrosion in a coaxial
connector or the antenna itself can create a fault. The corrosion can act like a
very poor diode and cause just a little bit of intermodulation.
Overload from a Legitimate Transmitter: Sometimes, strong signals from a
transmitter at any frequency can overload a neighboring system. The only
solution is to install a filter on the receiver antenna cable that will pass the
intended signals and attenuate the overload signal.
Adjacent Channel Power from a Neighboring Transmitter: If the allocated
spectrum becomes crowded, there can be some problems too.
Harmonics from Broadcast Transmitters: Also high-powered commercial
broadcast stations can produce substantial energy in harmonics of their signals.
For example, a 5-megawatt transmitter can easily generate 5 watts of harmonics
— more than enough to interfere with nearby mobile communications.
Communication Technologies, Transmission Frequencies, and Sample Rates in Local Area Network |
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Use the following chart to analyze communication technologies and technical characteristics use in LANs as art aid in selected appropriate test instruments. |
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Communication Technologies |
Date Rate | Communication Medium |
No. of Fibers/ Wire Pairs |
Encoding | Transmission Frequency |
Digital Oscilloscope Sampling Rate |
FDDI | 100 Mbps | fiber optic |
2 | 4B5B | 125 MHz | 250 Msamples/s |
CDDI | 100 Mbps | twisted pair | 4 | MLT-3 | 31.25MHz | 62.5Msamples/s |
10base-T | 10 Mbps/s | twisted pair | 2 | Manchester | 20MHz | 48 Msample/s |
10Obase-T | 100 Mb/s | Twisted Pair | 4 | 8B/6T | 25Mhz | 50 Msample/s |
Gigabit | 1000 Mb/s copper | twisted pair | 4 | PA M5 | 125 MHz/per pair |
250 Msample/s |
Gigabit | 1000 Mb/s copper | X | 2 | 8B /10B | 1.25 GHz | 2.5 Gsample/s |
ATM | 155 Mb/s | twisted pair | 2 | CAP-64 | 25 MHz | 50 Msamples/s |
ATM | 155 Mb/s fiber | multimode | 2 | 8 B10B | 194.4 MHz | 388 Msample/s |
ATM | 155 Mb/s fiber | plastic fiber | 2 | NRZ | 155.520 MHz | 311 Msample/ |
ATM | 155 Mb/s Fiber | Single mode | 2 | Scrambled 1+X6+X7 | 155.520 MHz | 311 Msample/s |
ATM | 622 Mb/s Fiber | Single mode | 2 | Scrambled 1+X6+X7 | 622.080 MHz | 1.24 Gsample/s |
ATM | 2.4 Gb/s fiber | Single mode | 2 | Scrambled 1+X6+X7 | 2.48832 ) GHz | 4.9 Gsample/s |
ATM | 9.9 Gb/s Fiber | single mode | 2 | Scrambled 1+X6_X7 | 9.953280 GHz | 19.9 Gsample/s |
n The
Solutions: Interference can be categorized by its own characteristics. It
can be found at the base station and in the air interfaces with the mobiles.
Interference signals only affect receivers–even when they are physically close
to a transmitter, the transmission will not be affected. The frequency of the
offender is the most common indicator of the source and consequences of the
interference. The solutions lie in hunting for sources of interference in the
networks and fixing them. There are test tools and techniques for managing the
same. The field transmitter and interference tester can be used.
Data Link Layout Audit Measurements: (OSI Layer2) |
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Ethernet | Token Ring | FDDI | ATM | WAN | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Measurements at the Base Station Receiver: The best way to hunt for
interference in the base station receiver is to disable traffic on the channel
to be measured. This will assure that no calls are assigned to it and the only
signals that you will see are the interfering ones.
Using Automatic Spectrum Analysis: A BTS tester can be used for this
purpose. There is no need to adjust controls such as resolution bandwidth or
video bandwidth as these are automatically set internally. If the signals are
constantly changing amplitude (as with GSM, for example), one may not catch the
signals at their maximum when you press AutoLevel. If the levels increase beyond
range, a warning banner on the screen will ask to decrease the reference level.
Finding Overlap in the Network: One of the more difficult problems to
resolve is overlapping coverage. If a BTS is located on high ground, its
coverage may unintentionally exceed the engineering plan. If the coverage is so
great that it overlaps a cell that has the same control channel (BCCH for GSM),
then the mobile can no longer distinguish between the two and is put out of
service in the area of overlap. A directional antenna will let you determine the
source of each of the overlapping signals. Moving in those directions will
confirm which of the base stations is causing the extended overlap.
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