Optimising DAS installations: Page 4 of 5

April 20, 2016 // By John Spindler, Zinwave
Optimising DAS installations
Given that installation costs can amount to 50 or 60 percent of the total cost of a distributed antenna system (DAS) deployment, it’s important to select systems and cabling that minimise total cost of ownership (TCO). This article will take a look at three key factors in DAS installations that can impact TCO, which includes cable selection, future proofing, and facilities use.

To add that additional amplifier to a conventional DAS you may need to add another card or blade into the head end, the intermediate hub (if one is being used), and in the remote unit, assuming the remote is a chassis which is closet-mounted and can accept cards or blades. With a self-contained ceiling-mounted remote – which is typically found in an all-fibre DAS – you would have to insert an add-on module, or you would add a second remote. That second remote would have to be daisy-chained off the primary remote, and if that’s not possible, then you would end up deploying a whole new second layer of equipment simply to support one additional frequency.  And this may be the case in any event if there is no additional space (card slots) in the head-end, intermediate hub, or remote chassis.

Figure 2: A DAS head-end.


A truly wideband DAS is different; it uses a single amplifier that covers every frequency. Because of the high-power nature of this amplifier, it allows you to spread the amp’s power across multiple frequencies – as well as operators using those frequencies – while being able to balance the power output at the end of the remote so that coverage is consistent for each and every frequency.


Facilities use


When deploying a DAS, space for the needed equipment is always an issue. Equipment uses space, power, and cooling resources, so the size of the overall system impacts TCO.


There’s a difference in size between types of DAS systems. Hybrid fibre coax systems, in particular, can be fairly large. Most hybrid fibre coax systems have a head-end hub which is rack mounted and can easily be accommodated in a standard telecom or IT room, but the remotes, which are typically 4-6U high rack- or wall-mounted units, go in the tight confines of a wiring closet. Finding the necessary space and power for these units can often be a challenge. You should also consider the amount of space the cabling takes – it spreads from the remote unit to 4-8 antenna points, and that’s a pretty heavy footprint caused by the cable infrastructure when you are using heavy coax.

Figure 3: A ceiling-mounted RAU.


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