In our last blog entry we outlined how the optimisation of an in-building distributed antenna system (DAS) is a function of three main things: coverage, capacity and infrastructure. Good coverage brings efficient signal propagation. Plenty of capacity is required to achieve maximum throughput. And with the increased capacity demand created by new generation mobile technologies, a future-proof infrastructure is required early on in the installation phase.
In this series of three blogs, Moti Shalev, Director of Product Management at Axell Wireless, summarises a recently produced whitepaper, covering how combining high- and low-power remotes on the same DAS can provide flexible network designs which right-size the solution to the requirement, and reduce costs.
In this final blog in the series, we’ll take a look at function number three: infrastructure.
Having addressed coverage and capacity at the design stage, progressing towards installation, operators can future-proof a DAS system to be ready for capacity growth simply by adding more sectors, without the need to revisit the infrastructure. Flexibility in the fibre optic head end unit can allow support for up to eight sectors from a single head end – if an installation starts with two sectors, for example, capacity can be doubled twice without the need to change the infrastructure, add more head end or remote units or fibre optic or coaxial cables.
One fully integrated solution enables the same cables to be used from the remotes to the head-end/s. Changes can be effected in the point of interface. ‘Carrier-grade’ IP backhaul for small cells or Wi-Fi access points can be fed off the DAS. This feature reduces both CAPEX and OPEX since there is no need for the operator to deal with multiple vendors for different systems, there is no requirement for the complex cabling that would result from such an approach, and no need for the increased costs of running separate systems in one location. In terms of the efficiency of the network, there will also be less RF interference.
The logical conclusion
Running separate infrastructure for the DAS and each set of IP devices increases the installation time and cost and can also cause potential interference between the systems.
Operators can now utilise a single infrastructure over a single fibre optic cable, supporting both the DAS remote units and the IP backhaul applications. The favourable cost implications are self-evident but it is perhaps more in the innate scalability and liberating flexibility of the DAS that the true long-term benefits reside.
Scalability is innate due to the design approach of ‘sectorisation’ whereby remotes can be added as capacity and coverage is required. Flexibility is ‘liberating’ because operators are no more constrained by fixed and rigid structures that require major re-investment as wireless communications technology rolls forward which, as the forecasts show, will continue to be the defining characteristic of the mobile world for some years to come.
Key to DAS optimisation is the requirement to take real world considerations into account when designing the infrastructure, establish architecture which permits growth through the inclusion of additional repeaters as and when required, and ensure high quality through the lowest attainable noise figure, which means deploying the highest quality equipment: three simple steps towards one clearly logical solution.
Product Marketing Manager, Axell WirelessMoti Shalev joined Axell Wireless in 2009 as Product Marketing Manager with the responsibility for defining the product management strategy. Moti has a B.S.C EE in Electrical Engineering and over 20 years of worldwide experience in the telecommunications industry.
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