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Count on FiberWork´s Next Generation Expert Professionals to characterize, evaluate, remediate and design your 400Gb/s DWDM optical transmission network.


Optical communication technologies have evolved enormously recently. Ten years ago, it was typified by:

  • Low bit rate and short distance optical transmission (ex.: 2.5Gbs, 10Gbs @ 60km to 400km);
  • Data processing done in the electronic domain at the network nodes;
  • ON-OFF intensity modulation and direct detection of NRZ/RZ coded bits;
  • EDFA optical amplification;
  • ´Optics´ was not an important concern in the transmission system design since the optical fiber acted as a transparent medium.

Nowadays optical communication technologies are typified by:

  • 100Gb/s bit rates per optical channel, moving towards 400Gb/s;
  • Increasing numbers of optical channels multiplexed together in a same fiber, i.e., high channel count DWDM systems;
  • Data processing turning more and more into the optical domain by using ROADM´s, OXC´s, optical packet switching, integrated photonic circuits etc;
  • Phase, polarization and amplitude modulation of the light signals, sophisticated bit-coding schemes as DP-QPSK and DQPSK;
  • Coherent detection technology;
  • Growing need for Raman amplification;
  • Optical impairments and OSNR have become key concerns in the transmission network design.

Implications for Telecom Carriers & Datacenter Businesses:
The above evolution means that nowadays the optical characteristics of the fiber plant must be accurately measured and precisely analyzed by expert professionals, who bear deep understanding of optical communication technology and optical metrology. The fiber measurements and analysis results must then be knowledgeably entered in the network design process. Doing so, the transmission network will be not only properly designed but also have an optimized design which will incur in lower capex investments and lower operational expenditures during its lifetime. This shall lead to a higher ROI and a longer life investment, which are important concerns in our current fast-evolving technology world, which obsoletes technologies and investments very quickly.
Data will soon become major international trading goods and the datacenter+cloud sector is to become a new pillar for the world economy. The growth of this sector is directly related with improving its data pipes, which are fiber based. Actually, optical communication is one of the most important underlying technologies for the datacenter/cloud business. Optical communications find a variety of applications within the datacenter world, and backbone optical transmission is one of them. Therefore, the same optical transmission concerns that affects the telecom carrier world also apply to the datacenter world.

Implications for Utility Companies:
With time, the transmission technologies of the past become less and less available in the market. So, not only they provide lower transmission capacity and inferior capabilities but they also become more expensive to install and operate. This forces utility companies, which may not require the highest-capacity state-of-the-art transmission technology, to follow telecom-pushed criteria when considering investments in optical transmission systems. This means that, in order to make optimized capex and opex investments, utilities should consider the same newest technologies made available in the market for the telecom market sector. This also means that utilities must have the same concerns and worries as telecom companies when dealing with their fiber network investments. Such points are easily understood by making a parallel with the computer industry. Although one may require for his application a processing speed of only 400MHz, he will find it hard to buy a computer with such old specification, and the initial cost and operating cost of such computer will turn out to be more expensive than the current 3GHz dual-core computer machines. On the other hand, one should also have in mind that newer bandwidth-hungry applications are continuously appearing in the market. In summary, utility companies are be better off opting for the higher capacity state-of-the-art transmission technology developed for the telecom sector.

Implications for the Mobiles Business:
Optical communications is the pillar of the mobile communication business. A wireless network exists only between the subscriber and the nearest base station tower, i.e., a very short communication reach which needs to be further reduced in order to make technically feasible broadband access via mobile gadgets. From the base station forward, the communication becomes optical, i.e., the mobile business relies on fiber-based backhaul networks. Therefore, every new cycle of wireless technology innovation brings new demands to the fiber optic backhaul and transportnetworks operated by the wireless businesses. Wireless telecom operators have recently upgraded their fiber networks to allow for the 4G introduction and will soon need it again for the introduction of 5G. Implications for the Broadband Access Business: Optical communications is also the pillar of the broadband access business. The residential broadband access based on DSL technology relies on copper cables between the subscriber home and the DSLAM, which is housed in street shelves or switch offices in the subscriber neighbored. From the DSLAM forward, the communication becomes optical. Moreover, in the residential broadband access business, the copper pairs are quickly been replaced by Fiber-To-The-Home (FTTH). So, the higher the bandwidth in the residential access, the more optical-fiber dependent it becomes. In parallel, the growth of the broadband access business and the introduction of digital media and HDTV foster higher bandwidth demands in metropolitan, long distance and submarine transmission networks. Thus, optical transmission upgrades become inevitable as well.

Not all DWDM Systems Are Made Equal!
You have bought an 80 channel DWDM system. You have lit 2x 100Gb/s channels at first and now, 1 year later, your customer demand has grown and therefore you want to light additional DWDM channels in your DWDM system. Actually, you just want to do what the marketing advertises: DWDM = a grow-as-you-go investment. However, by adding new DWDM channels, your BER extrapolates acceptable levels. Your system vendor replies to you saying that your fiber network is optically impaired and that there is nothing wrong with the system he has supplied, so you can´t claim on the vendor´s warranty clause (the warranty deadline has passed anyway). Unfortunately, he is right! The problem is within your fiber network. Therefore you end up with a loss, as you bought an 80 channel DWDM and ends up been able to use only 2 channels. Your vendor will see this as a great opportunity to, again, surf on your technical naivety and market his latest painkiller: a network redesign and re-fitting, adding Raman amplifiers and other expensive equipments for overcoming poor network OSNR. The mistake was that your fiber network was not diagnosed before writing your system equipment RFP. Had it been done so, you would have not only bought the most appropriate DWDM transmission system, that best fitted your fiber network, but also got the most cost-effective solution that would surely light all planned DWDM capacity. You should now have learned that even a good lawyer’s turnkey contract cannot replace deep technology expertise. To be indeed profitable, investments in optical communications requires broad and deep technology expertise, from knowledgeable experienced optical communication technology experts.

The Coherent Salvation:
Coherent optical communication technology has become the salvation of old fiber networks. By allowing mitigating the optical impairments in the electronic domain, it renders additional lifetime to old and optically-impaired fiber plants. Without the coherent optical technology, these networks would reach their end of life with 10Gb/s transmission channels. While the coherent technology helps overcoming the PMD (polarization mode dispersion) and (CD) chromatic dispersion impairments, OSNR (optical signal to noise ratio) then becomes the hard issue to deal with. Because of that, the once miraculous Erbium fiber amplifier has to be partially replaced by Raman amplification. This remedy has however a high cost and adds complexity and safety issues to the system network design, so not all networks may be worth it. FiberWork´s specialized optical network diagnostics provide you the most profitable and best ROI decision for your fiber network.
PMD and CD are impairments built within the fiber. Coherent detection technology provides a way to compensate for them in the electronics domain, which does not mean that such impairments have disappeared from the fiber. Actually, it means that additional hardware (and CAPEX) will be required to sort such impairments out. For future higher transmission capacity, such as 400 Gb/s and beyond, even coherent detection will face limitations when dealing with PMD and CD. In summary, carriers will be much better off if their fiber networks do not bear high PMD and CD impairments. That is a very important point to consider when negotiating 20-year long fiber swaps, leases and IRU´s.

Think 100+ Gb/s! Think Next Generation Professionals! Think FiberWork!
FiberWork’s fiber network diagnostics is a specialized and innovative service created by FiberWork. It comprises in-depth analysis by expert PhD professionals of fiber characterization data and extensive network assessment. The outcome is a set of recommendations intended towards network design optimization, corrective maintenance, capex and opex savings, better exploitation of fiber transmission capacities and future-proofing the network investment. Additionally, network grooming and remediation can be provided along with the diagnostics service. This grooming improves the OSNR of old installed fibers, therefore allowing to light 100Gbs channels in such fibers as well as reduce Raman amplifier count and increase the maximum number of allowed DWDM channels.

Negotiating or Swapping Dark Fibers? Evaluate it in Advance with FiberWork!
FiberWork’s diagnostics of installed fiber networks provides important support for decision making before network design and upgrade as well as for dark fiber valuation, needed for fiber swap, leasing and IRU negotiations. It helps both sides of the table, providing fairer negotiations.

FiberWork: Bringing You Into the Future of Optical Communications!
Making assertive and future-proof decisions and investments are imperative for telecom carriers, utilities and mobile businesses that intend to keep alive and competitive in our fast technology-changing environment. Minor technical mistakes may reflect in great money losses in capex and future opex. FiberWork Optical Communications´ products and services are the tools that visionary carriers and utilities need to anticipate and strategically position themselves for the new eras of optical communications. FiberWork helps you to extend the useful life of your optical network and increase the ROI of your telecommunication investments.

FiberWork Optical Communications - Call for the Next Generation Experts!