Fibre Deployment Best Practice
UTEL has had the privilege of working with some of the world's largest early adopters of fibre PONs in both Asia and Europe. These pioneers have learnt a lot of hard lessons on their journey. Many would probably approach their roll-outs very differently if they could start all over again today. Here we give you the opportunity to gain their learning experience the painless way!
Dogs can joint copper but it takes a cat to install fibre
Project Managers building their PON roll-out cost spreadsheets always forget to add a critical column: - 'Cost of Failure'. This may sound ridiculous to fibre newbies, but experienced old hands know that if 70% of your customer PON connections work first time, without the need for a truck roll and remedial work, then you are not doing particularly badly. The underlying reason for this high failure rate is human operator indiscipline and optical component deficiencies.
Fibre-optics can be best understood as 'light' plumbing on a microscopic scale. In order to connect two optical fibres you need to perfectly align the fibre cores which are only 10 microns in diameter, To put this into context, a human hair is 17 to 181 microns in diameter. If the two fibre cores are not perfectly aligned, then you will only get a trickle of light coming out the other end. A bad adapter ferrule or just an unlucky speck of dust on a connector can be enough to introduce a critical optical path loss. Bending optical fibres beyond their critical radius will also result in light 'leaking' out of the core which will create more unforeseen optical path losses. Standard G.652 fibre has a minimum bend radius of 30mm and even the best G.657.B3 low bend radius fibre should not be bent below a 5mm radius.
All of these strange phenomena are difficult to comprehend if you have spent your life jointing copper pairs which is a simple, reliable and totally predictable process. The blades in the jelly crimps or IDC strips cut through dirt, grease and insulation making a perfect electrical connection every time. Copper pairs can be bent at 90 degree angles without affecting service.
The skill and attitude requirements for connecting fibre and copper are as different as dogs and cats. Dogs are rough and ready creatures whereas cats have precision body control, total focus and instinctive cleanliness. If you asked a dog to connect fibre, chances are it will not work, as it will have slobbered over the connectors before plugging them together. A cat on the other hand will have cleaned the connectors at least twice and will have carefully inspected them before plugging them together. You would not expect to turn a dog into a a cat by making it attend a two hour meowing course, at the end of which it would probably be growling and not meowing. It is similarly unrealistic to expect copper jointers to accept 'mindless fibre connector cleaning rituals' or to really believe that bending a fibre too much will really impair service. The only way to really instil this knowledge is through intensive practical retraining where the technicians actually learn to understand how easy it is to contaminate a connector and personally measure the power loss as they they bend a fibre beyond its critical radius!
Anecdote: UTEL were working with a long established service provider in Ireland who was experiencing major problems with splitters installed by contract labour. A superficial inspection of the splitters showed that 'Company A's work looked very professional, they had even 'laced ' the incoming fibre while 'Company B' s installation practices looked pretty sloppy. UTEL carried out an OTDR scan of the PONs from the OLT and we were all surprised to find that Company A's installations had far higher optical losses. After examining Company A's Splitter installations it was clear that these guys were trying to do a really impressive job but did not understand fibre installation. They had tied back fibre using tie wraps creating losses by exceeding the critical bend radius of the fibre and also failed to methodically clean the connectors before plugging them into the northbound adapter on the splitters.
The 'cost of failure' of bad fibre installation is further exacerbated by the fact that fibre networks are generally built in stages. Fibres are usually installed first from the OLT out to the splitter locations. The splitters are then connected and then sometime later customers are connected to the individual splitter outputs. Far too often the customer circuits fail to work because of excessive optical losses at the splitter input. Very often this initial splitter installation work is subcontracted and paid for a long time before the first customer is connected. The installation fails because of a dirty primary splitter connector. The fault is only remedied after an unnecessary field investigation with a hand held OTDR. The cost of failure is not just the monetary cost of the truck role but also the disruptive impact it has on the service providers roll out programme and his reputation.
Most service providers have spent many sleepless nights trying to find ways to address this issue. Some service providers now require their installers to connect a visible light source at the OLT end of the fibre and then take a picture of the glowing fibre tails plugged into the splitter outputs as proof that the installation has been completed successfully. Another solution that has been tried is to require the installer to record hand held OTDR traces looking back through the splitter and to send them in for verification.
Unfortunately all of these control mechanisms rely on the motivation and integrity of the individual installer. If you are a contractor, low down in the food chain, on minimal piece rate payments your motivation will be fairly obvious. Do you spend as little time as possible on the job to maximise your personal income so that you can look after your family or do you worry about the quality of the optical circuits that you are building? Tough decision! Chances are that the service provider will not be burning even more money paying technically competent people to check your OTDR plots or fibre photos! Even if he does, all it means is that you need to keep a selection of good pictures and graphs to keep them entertained.
Properly verifying the optical quality of individual PONs as they are built is the only way to avoid the much larger cost of failed customer connections. The only issue is finding a mechanism that works! More on that later.
Fibre-optics has moved on leaps and bounds in the past two decades and innovation is still happening each and every day. Unfortunately many incumbent service providers fail to keep up with current best practice and are still stuck in a time warp pushing superseded fibre technologies like blown fibre or single fibre splice trays. These technologies may have been great ideas in there time, dreamt up by expensive academics in ivory towers, but the world has moved on. If you want to identify leading edge 'best practice' today, look at what the Tier 2s are doing. These guys are lean and hungry and brutally focussed on building the best possible PON networks at the lowest possible cost. They are the evolutionary hotspots where new ideas are constantly being put into practice.
The best way to connect fibre
The wonderful thing about copper pairs was that you could simply cut them to length and crimp them together virtually anywhere. Fibre unfortunately is significantly more difficult to connect. There are three ways that you can connect fibres. You can splice fibres, you can plug two fibres together using factory fitted connectors or you can plug them together using field connectors.
Spliced connections will provide the lowest optical losses as you are literally welding the two glass cores together. Making good spliced connections is a skilled job, you will need a properly trained operator with access to a good quality splice machine. The splice machines also need to be properly serviced and maintained and there are also stringent health and safety issues associated with the disposal of cleaved fibre shards. Fibres can only be spliced in a controlled environment with plenty of light and shelter from the outside elements, it is not something that can be done up a telephone poll. Splicing is the right technology to connect multi-fibre cables in the core network but it has been displaced by connectorised technology in PONs where the only splicing that is done is connecting fibre pigtails to the near end of pre-connectorised cables.
Factory made connectorised cables and splitters have established themselves as the industry preferred practice for rolling out PONs. Factory pre-connectorisation dramatically reduces installation time, skill requirements and cost and enables service providers to buy pre-tested connectivity. Industry best practice is to use fibre drop cables pre-terminated to customer termination boxes. This minimises installation time in the customer premises and as the fibre connection has been factory pre-tested, the service provider has certainty that this connection is always good.
Field connectors initially appeared to be a great innovation as they allowed fibres to be be cut to length and connectorised without the cost and complexity of splicing. Unfortunately the technology has proved to be unreliable and has been largely abandoned.
Anecdote: Field connectors were mass deployed in China but proved to be unreliable as ageing and thermal expansion can result in the fibre moving causing service loss. Field connectors are now being replaced with spliced pigtails whenever a customer reports a fault.
The price of assured quality
Buying optical components is not easy. The established European, Japanese and US suppliers will all insist that only 'they' can provide 'quality' fibre optic products. On the other hand you have suppliers from China offering superficially identical products at a tiny fraction of their prices.
Can you trust products from China? The answer is that you get what you want to pay for in China. China is now the world's factory and manufactures products for virtually all of the world's famous brand name manufacturers. If you want cheap, you can buy ridiculously cheap in China but don't expect it to meet your quality expectations. If you want to buy assured quality, then Chinese manufacturers can also supply high quality products but they will cost a bit more, but they can still provide massive savings with respect to the offerings of Japanese and European manufacturers, which incidentally may also be made in China!
Anecdote: Many years back when UTEL started moving into fibre technologies our company was doing R&D on robotic optical cross connect machines and we undertook a massive evaluation of patch cables and adapters to try and better understand the wide and erratic distribution that we were getting in optical connection losses. The underlying cause of failure was not just bad polishing of the connector ends as we had initially suspected, but low quality ceramic ferrules in the connectors and the adapters. At the time we started only buying (very expensive) famous brand name Japanese adapters and patch cables, which sorted out our immediate problem, but it also gave us the impetus to later build a global volume supply chain for low cost quality optical fibre infrastructure products from China.
There are a lot of suppliers who can provide high quality optical components. There are also a lot of suppliers who can provide low cost products from China, directly or as resellers and everyone knows the joke about how all Chinese vendors speak perfect English but their complaints departments only understand Mandarin.
Five years ago, our company UTEL established its own high-tech joint venture in Nanjing in China to exploit our leading edge PON OTDR technology. As a follow on, we set up our own Chinese R&D and QA teams to enable us to become a major player in the European fibre infrastructure market.
Our initial target market was France where fibre was rapidly taking off as a result of innovative and intelligent government regulation. Today we are are the suppliers of choice for the lean and hungry French Tier 2s and our business is growing exponentially as we have succeeded in marrying UTEL innovation with strict quality control, pan European logistics and Chinese volume production and pricing. This year based on the success of our French pilot, we are expanding our distribution network throughout the EU and the UK.
If you are looking for an ultra-competitive long term reliable supply partner for your PON roll out then look no further than www.utelfastlight.com.
Yes, you could set up your own Chinese supply chain, but trust me it is not easy! Anyone can find 'low cost' suppliers on Alibaba and Made in China but establishing and maintaining a reliable long term supply chain is incredibly difficult.
Our UTEL business model is very simple. We have a top notch team in China who control sub-contract manufacturing in multiple factories in China. We own the vast majority of the injection mold tools and CAD CAM files for the metalwork that we manufacture in China. We have our own Chinese engineering design teams who can rapidly create new or better products that precisely meet our customer's requirements. We redesign and optimise and not simply re-badge existing Chinese products. Our quality control teams inspect EVERY batch so we never load anything into a container that is less than perfect. We make our money being better at less cost which is something you can never do as a reseller. UTEL is structured very much like our successful customers, lean, mean, hungry and totally focussed on the next meal! Flat hierarchies, focussed top quality people and no suits hiding behind job titles. We know what our our customers want:- innovation, quality, reliability and responsiveness with European stock and of course eye-watering worlds-best pricing. This is exactly what we deliver.
We bring in multiple 40 foot containers every week into our French warehouses from our own sub contracted factories in China and maintain European stocks against forecasts for our established customers. We use leading pan-European logistics partners to get supplies to our customers when they need them. Most importantly we have a lot of Chinese manufacturers chasing our volume business which keeps their pencils sharpened. This in a nutshell is the secret of our success. We supply innovative fibre products at ulta-competitive prices with multi-million Euro local stocks for our established customers. Why not join the club and enjoy success?
You have only ONE chance to fully capture your PON network data and build a long term sustainable network
Service providers have one opportunity to economically capture their optical network data and that is when they build their PON networks. This may appear quite obvious which makes it even more disappointing that most service providers fail to do it.
The underlying reason for this failure is that the service providers are intensively focused on their short term objectives and lack the necessary longer term vision. Most service providers have no real idea of how they are going to manage their operational networks and have little interest in 'wasting their time' worrying about this until they have their networks built. Unfortunately, they will have painted themselves into a corner by this time and will have burdened themselves with ongoing 'forever' costs that cannot be economically rectified.
The 'cost of failure' associated with this omission is absolutely massive and can easily be avoided with a bit of forethought focus and planning.
Using today's technology it is not only easy to collect GPS location data for cable access points and splitters but it is also possible to capture actual splitter loss data using barcodes printed on the splitters. It is also possible to automatically measure the actual losses to each splitter leg connection and compare this with what it should be.
When a customer is connected to a PON it it is also very easy to build the customer data and to automatically identify the customer's ONT reflection on a central office OTDR plot. If you use RFTS PON testing to take the costs and frustration out of your PON rollout, you will also build a PON network that is fully automatically optically testable to each customer's ONT. The ongoing long term benefit of this is that you will no longer need to dispatch quality technicians with hand held OTDRs to fault PONs and you will meet all of your PON SLAs without stress or cost FOREVER AND EVER.
There is only one economic way to properly test individual PON networks and that is to test them using a proper OTDR Remote Fibre Test System. Using today's technology it is possible for an OTDR to see the individual ONT optical reflections through even a 128 way split without requiring expensive test wavelength reflectors. The only requirement is that the individual fibres connecting the ONTs to the splitters are staggered by at least 2m to enable the OTDR to distinguish the individual reflections. This critical implementation issue can only be cost effectively implemented during the customer connection to the PON. If you do not build this customer data during the installation phase you will never get a second chance!