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FEATURE MOBILE BACKHAUL


Backhauling with fibre?


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


S


ince the first mobile phones were introduced in 1981, mobile networks 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, 3G, 4G and Long Term Evolution (LTE) 4G, the maximum capacity that must be supported by each mobile cell has progressively increased in response to an exponential rise in data consumption. But things are going to get even more


demanding for mobile networks when the Internet of Tings (IoT) finally takes off and all kind of sensors and tracking devices with Internet connections start to share data. By the end of this decade, analysts predict that 50 billion of these sensors will connect to mobile networks consuming 1000 times as much data as today’s mobile gadgets alone. Tis will be challenging for mobile networks that will have to backhaul massive amounts of data. To avoid having to purchase expensive new


mobile spectrum (that might not be available anyway), the only way mobile operators can further increase the bandwidth available per user is to increase the density of cell sites. In congested urban areas this means the adoption of outdoor small-cells. However, as these small cells will mostly


aggregate to the nearby macrocell site, this strategy does not fundamentally reduce the amount of data that ultimately needs to be backhauled. In fact it is more likely to increase, especially when 5G becomes operational in the future. Mobile operators acknowledge this capacity


challenge and recognise that deploying optical fibre provides a superior technical solution compared to all other alternatives. But despite its


Micro-trenching is particularly suited to roadways and sidewalks where utilities are already present beneath the road surface. It requires only a shallow trench, typically about 15cm deep


unlimited bandwidth, reliability, low latency, and jitter, fibre penetration in the backhaul has been relatively slow compared to microwave solutions. Tis situation commonly prevails because the


upfront cost is the most important factor in the operator’s installation decision and fibre is still regarded as an expensive option to deploy with a long pay-back period.


Behind the numbers


Based on publicly available research data, Corning has designed an economic model to compare the total cost of ownership (TCO) of some of the most common backhaul technologies (microwave, millimeter, leased fibre and new fibre deployment). Te model compares the cost of backhauling a macrocell site with a tri-sectorial antenna (with each sector operating at 80 Mb/s) situated 3 km from the nearest aggregation site and connected to it via a point-to-point (P2P) link using one of the methods listed above. When considering the first installed costs only,


deploying optical fibre cable using traditional open trenching is the most capital-intensive solution. Tis is because open trenching is an expensive, disruptive and slow process, particularly in urban areas with prices varying from €95-157 per metre and installation speeds of only 30 to 50m a day (typical prices in the UK). For this reason some operators have opted for


leasing fibre bandwidth as a way of securing high capacity without incurring the capital cost of installing cable. However, the high leasing fees with prices varying from €40,000 to €112,000 per year for a macrocell site, make this alternative a short-term rather than a long-term solution. A lower first-installed cost explains why wireless


technologies might seem to be a more cost-effective solution than fibre. However, wireless equipment


The breakeven point between fibre and wireless backhaul can be reduced to just 6-8 years


can incur considerable and on-going operational costs for spectrum leasing, particularly in urban areas where some of the most common frequency bands currently used are becoming congested and expensive. For example, the UK regulator Ofcom sets a license fee for a 23 GHz link using two 56 MHz channels of €2,827 per year per link. Millimetre wireless bands can offer increased bandwidth and spectrum fees as low as €64 per


Issue 6 • Winter 2015 FIBRE SYSTEMS 33


Ditch Witch


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