| FEATURE @fibresystemsmag www.fibre-systems.com MOBILE BACKHAUL Backhauling with fibre?

Modern installation techniques and smaller, Ditch Witch lighter cables enable more economical fibre deployment in mobile backhaul networks, writes Vanesa Diaz

ince the first mobile phones were introduced in 1981, mobile networks S have evolved to the point that we can now be connected anywhere and get to see, experience, explore and express ourselves with just a click from the palm of our hand. From 2G, Micro-trenching is particularly suited to roadways and sidewalks where utilities are already present , 4G and Long Term Evolution (LTE) 4G, the beneath the road surface. It requires only a shallow trench, typically about 15cm deep maximum capacity that must be supported by each mobile cell has progressively increased in response unlimited , reliability, low latency, and leasing fibre bandwidth as a way of securing high to an exponential rise in data consumption. jitter, fibre penetration in the backhaul has been capacity without incurring the capital cost of But things are going to get even more relatively slow compared to microwave solutions. installing cable. However, the high leasing fees demanding for mobile networks when the This situation commonly prevails because the with prices varying from €40,000 to €112,000 per of Things (IoT) finally takes off and all kind of upfront cost is the most important factor in the year for a macrocell site, make this alternative a sensors and tracking devices with Internet operator’s installation decision and fibre is still short-term rather than a long-term solution. connections start to share data. By the end of this regarded as an expensive option to deploy with a A lower first-installed cost explains why wireless decade, analysts predict that 50 billion of these long pay-back period. technologies might seem to be a more cost-effective sensors will connect to mobile networks solution than fibre. However, wireless equipment consuming 1000 times as much data as today’s Behind the numbers mobile gadgets alone. This will be challenging for Based on publicly available research data, Corning mobile networks that will have to backhaul has designed an economic model to compare the massive amounts of data. total cost of ownership (TCO) of some of the most The breakeven point To avoid having to purchase expensive new common backhaul technologies (microwave, between fibre and mobile spectrum (that might not be available millimeter, leased fibre and new fibre deployment). anyway), the only way mobile operators can The model compares the cost of backhauling a wireless backhaul further increase the bandwidth available per user is macrocell site with a tri-sectorial antenna (with can be reduced to to increase the density of cell sites. In congested each sector operating at 80 Mb/s) situated 3 km just 6-8 years urban areas this means the adoption of outdoor from the nearest aggregation site and connected to small-cells. it via a point-to-point (P2P) link using one of the However, as these small cells will mostly methods listed above. aggregate to the nearby macrocell site, this strategy When considering the first installed costs only, can incur considerable and on-going operational does not fundamentally reduce the amount of data deploying optical fibre cable using traditional open costs for spectrum leasing, particularly in urban that ultimately needs to be backhauled. In fact it is trenching is the most capital-intensive solution. areas where some of the most common frequency more likely to increase, especially when 5G This is because open trenching is an expensive, bands currently used are becoming congested and becomes operational in the future. disruptive and slow process, particularly in urban expensive. For example, the UK regulator Ofcom Mobile operators acknowledge this capacity areas with prices varying from €95-157 per metre sets a license fee for a 23 GHz link using two challenge and recognise that deploying optical and installation speeds of only 30 to 50m a day 56 MHz channels of €2,827 per year per link. fibre provides a superior technical solution (typical prices in the UK). Millimetre wireless bands can offer increased compared to all other alternatives. But despite its For this reason some operators have opted for bandwidth and spectrum fees as low as €64 per

Issue 6 t Winter 2015 FIBRE SYSTEMS 33 FEATURE | MOBILE BACKHAUL @fibresystemsmag www.fibre-systems.com

year per link, but at these frequencies the Total cost of ownership comparison of installing various types of mobile backhaul equipment is more expensive and the maximum link distance is more limited, negatively impacting both deployment and maintenance costs. 0.40 Although once installed, the on-going costs of running fibre links are much lower than wireless, 0.35 due to the initial cost of traditional cable Open-trenching + LT cable installation the breakeven point for fibre relative to 0.30 microwave is somewhere between 18 and 20 years, which is too long to provide an acceptable business 0.25 case for the mobile operator. To allow operators to Leased BW Microwave realise their preferred option of using fibre to 0.20 address mobile backhaul capacity challenges, Millimeter improvements to cable installation technology are 0.15 Microtrenching + Minicable

necessary. CapEx + OpEx (€M) 0.10 2-way Consortium Micro-trenching, microduct Microtrenching + Minicable and minicables 0.05 Up to 80 per cent of the total costs of deploying new fibre are due to civil works. This is because 0.00 1234567891011121314151617181920 digging trenches in busy roads requires permits, traffic management and, once the ducts have been Year laid, reconstruction of the road by backfilling the hole and reinstating the surface. Alternative markets. There are also examples of operators bandwidth are also commercially available. By deployment techniques can notably reduce these sharing mobile spectrum and even network leasing either some of the microducts or the fibres costs and one in particular has become very construction costs, e.g. in 2009, Tele2 and Telenor contained therein, an operator who deploys cable popular. in Sweden formed a joint venture to build a using microduct technology can open new Microtrenching replaces traditional open nationwide 4G network and share spectrum. revenue streams that could completely change the trenches with a narrow slit that is sliced or sawn Because microducts sub-divide the internal business case for fibre deployment. into the surface of the road and into which duct into multiple smaller compartments this microducts are placed. Microducts are smaller technology is particularly well suited to allowing Conclusion versions of the pipes through which optical fibre the efficient sharing of duct-space amongst several Mobile operators need to install backhaul cable can be pulled, pushed or blown. They can be operators along a route. In Corning’s economic networks that are capable of supporting the procured and installed individually or in analysis, two operators working in a consortium expected growth in data carrying capacity. specially-designed bundles and into which smaller could share the costs of deploying a microduct Although microwave and millimeter technologies and lighter minicables are blown. bundle using microtrenching technology moving are more limited in terms of data capacity, these With the use of minicables, microducts, again the pay-back period relative to wireless technologies are often regarded as the low-cost microtrenching can allow less disruptive and solutions down to 2-3 years. alternatives and still lead the market, whereas fibre much quicker fibre deployments with speeds Duct space reutilisation. In brownfield has been perceived as a long-term investment and between 150 to 200m per day, reducing civil costs deployments, once a standard loose-tube cable is has often been discarded due to its high initial cost dramatically – as much as 76 per cent in one deployed in a large duct, installing new cables in of deployment. reported example in the US city of Linda Loma. In the same space is not recommended as it could However, the use of advanced installation Corning’s economic analysis, the large savings in damage both existing and new cables. However, by techniques and microcable can greatly reduce the deployment enabled by the use of microtrenching overlying microducts in the large duct first, initial level of investment of new fibre builds, and minicable/microduct technologies can reduce minicables can be air-blown in later at no risk, particularly if operators form a consortium to the breakeven point between deployed fibre and allowing carriers to reutilise crowded ducts that share costs. Operators may also open new revenue wireless solutions to 6-8 years. would otherwise have been considered full. This streams by leasing infrastructure to competitors There are several additional potential benefits of approach allows operators the opportunity to making the business case for fibre more attractive using minicable and microduct technologies in increase network capacity at relatively low cost. than ever before. O backhaul network deployment: Duct and dark fibre leasing. Leasing bandwidth, Infrastructure sharing. Interest is growing dark fibre or duct access is a common practice in Vanesa Diaz is market development engineer at Corning among operators in sharing backhaul Europe. In September 2010, the European infrastructure as a means of lowering overall Commission (EC) issued a Recommendation with Further reading network costs. Sharing masts for hosting the aim of regulating wholesale products in Next microwave antennas is a common arrangement Generation Access Networks (NGA). For Paolini, M. (2011). Crucial Economics for Mobile between mobile operators. For example, example, the cost of renting duct space in Telecom Data Backhaul. Retrieved from http://www.senza-fili.com/Resources/ Telefónica, O2 and Vodafone have a 10-year Portugal’s network in Lisbon is 10.60 euros/ WhitePapers.aspx network sharing agreement in selected European month/km/cm2 and options to lease dark fibre and

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