FEATURE MOBILE BACKHAUL


year per link, but at these frequencies the equipment is more expensive and the maximum link distance is more limited, negatively impacting both deployment and maintenance costs. Although once installed, the on-going costs of


running fibre links are much lower than wireless, due to the initial cost of traditional cable installation the breakeven point for fibre relative to microwave is somewhere between 18 and 20 years, which is too long to provide an acceptable business case for the mobile operator. To allow operators to realise their preferred option of using fibre to address mobile backhaul capacity challenges, improvements to cable installation technology are necessary.


Micro-trenching, microduct and minicables


Up to 80 per cent of the total costs of deploying new fibre are due to civil works. Tis is because digging trenches in busy roads requires permits, traffic management and, once the ducts have been laid, reconstruction of the road by backfilling the hole and reinstating the surface. Alternative deployment techniques can notably reduce these costs and one in particular has become very popular. Microtrenching replaces traditional open


trenches with a narrow slit that is sliced or sawn into the surface of the road and into which microducts are placed. Microducts are smaller versions of the pipes through which optical fibre cable can be pulled, pushed or blown. Tey can be procured and installed individually or in specially-designed bundles and into which smaller and lighter minicables are blown. With the use of minicables, microducts,


microtrenching can allow less disruptive and much quicker fibre deployments with speeds between 150 to 200m per day, reducing civil costs dramatically – as much as 76 per cent in one reported example in the US city of Linda Loma. In Corning’s economic analysis, the large savings in deployment enabled by the use of microtrenching and minicable/microduct technologies can reduce the breakeven point between deployed fibre and wireless solutions to 6-8 years. Tere are several additional potential benefits of


using minicable and microduct technologies in backhaul network deployment: Infrastructure sharing. Interest is growing among operators in sharing backhaul infrastructure as a means of lowering overall network costs. Sharing masts for hosting microwave antennas is a common arrangement between mobile operators. For example, Telefónica, O2 and Vodafone have a 10-year network sharing agreement in selected European


34 FIBRE SYSTEMS Issue 6 • Winter 2015


@fibresystemsmag | www.fibre-systems.com


Total cost of ownership comparison of installing various types of mobile backhaul


0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00


1 2 3 4


Open-trenching + LT cable


Leased BW


Microwave Millimeter


Microtrenching + Minicable


2-way Consortium Microtrenching + Minicable


5


6


7


8


9 10 11 12 13 14 15 16 17 18 19 20 Year


markets. Tere are also examples of operators sharing mobile spectrum and even network construction costs, e.g. in 2009, Tele2 and Telenor in Sweden formed a joint venture to build a nationwide 4G network and share spectrum. Because microducts sub-divide the internal


duct into multiple smaller compartments this technology is particularly well suited to allowing the efficient sharing of duct-space amongst several operators along a route. In Corning’s economic analysis, two operators working in a consortium could share the costs of deploying a microduct bundle using microtrenching technology moving again the pay-back period relative to wireless solutions down to 2-3 years. Duct space reutilisation. In brownfield deployments, once a standard loose-tube cable is deployed in a large duct, installing new cables in the same space is not recommended as it could damage both existing and new cables. However, by overlying microducts in the large duct first, minicables can be air-blown in later at no risk, allowing carriers to reutilise crowded ducts that would otherwise have been considered full. Tis approach allows operators the opportunity to increase network capacity at relatively low cost. Duct and dark fibre leasing. Leasing bandwidth, dark fibre or duct access is a common practice in Europe. In September 2010, the European Commission (EC) issued a Recommendation with the aim of regulating wholesale products in Next Generation Access Networks (NGA). For example, the cost of renting duct space in Telecom Portugal’s network in Lisbon is 10.60 euros/ month/km/cm2


and options to lease dark fibre and


bandwidth are also commercially available. By leasing either some of the microducts or the fibres contained therein, an operator who deploys cable using microduct technology can open new revenue streams that could completely change the business case for fibre deployment.


Conclusion


Mobile operators need to install backhaul networks that are capable of supporting the expected growth in data carrying capacity. Although microwave and millimeter technologies are more limited in terms of data capacity, these technologies are oſten regarded as the low-cost alternatives and still lead the market, whereas fibre has been perceived as a long-term investment and has oſten been discarded due to its high initial cost of deployment. However, the use of advanced installation


techniques and microcable can greatly reduce the initial level of investment of new fibre builds, particularly if operators form a consortium to share costs. Operators may also open new revenue streams by leasing infrastructure to competitors making the business case for fibre more attractive than ever before.l


Vanesa Diaz is market development engineer at Corning Optical Fiber


Further reading


Paolini, M. (2011). Crucial Economics for Mobile Data Backhaul. Retrieved from http://www.senza-fili.com/Resources/ WhitePapers.aspx


CapEx + OpEx (€M)


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