DAS Design Considerations
Coverage & Capacity: First consideration for a DAS design is type of venue/building that is the target of DAS deployment. A stadium will have a different requirements & challenges than a high-rise building in terms of number of sectors, coverage & capacity targets. An indoor arena would have to account for different event types to handle variably capacity compared to an airport. These different requirements will be key factor in determining DAS OEM, sectorization, Macro Interaction and DAS Handover zones.
Neutral Host: Next consideration is how many different vendors are going to use DAS, type of technologies they are planning to deploy, number of carriers operators are planning to utilize in different bands. This will change the amount of power available to different operators, technologies and bands. For LTE deployment plans, MIMO path capability is an important factor that may change number of remote units needed on each location directly affecting cost of deployment. Another key consideration is 3 to 5 year plan for each operator involved in DAS. This will help dimension design for future expansions without major hardware upgrade on passive side of DAS.
Benchmark Data: Recent Benchmark data is key to understand signal strength for different carriers/technologies prior to DAS deployment. A careful study and co-relation of benchmark data can help determine coverage targets to overcome existing DAS coverage. The data also help to understand current coverage in high-traffic areas (conference rooms, high-traffic areas, press-box, etc) and potential polluters after DAS deployment. Macro reduction opportunities are also considered for mitigation of potential macro interference to DAS.
Construction Materials: Construction materials will impact the propagation of signals and will be key to meet design criteria. Accurate floor-plans and Auto-cad files are important requirements to model any venue in iBwave in 3D. A pre-design site survey is very helpful to identify different construction material used in walls, ceilings and overall construction. Accurate modeling also helps with creating precise Bill of Materials. A good model takes into account conference rooms, special event sites, etc to be able to satisfy design criteria in such areas. Special attention may be needed for facilities which may have non-traditional materials used (Medical Imaging areas, Government buildings, etc.)
Equipment & Antennas: DAS OEM selection depends upon type of venue, amount of traffic, sectorization and type of services being planned at design phase. Space available for remote units, scalability of service, power requirements of DAS remotes, connectivity with fiber are additional factors that influence DAS OEM selection. If Depending on individual location, either Omni or Directional antenna can be selected. There are vast majority of manufacturers who make antennas that are specific applications. A Key consideration in antenna selection is the frequency range in which antenna is capable of operating. An expansion of services from operators should be taken into account to select appropriate equipment and antennas. Different operators may have different set of approved vendors for DAS OEMs, passive components and antennas. While designing neutral host venues, sometimes approved component selection supersedes best possible component selection for successful design.
Integration with Network: Ultimate objective of the DAS design is to provide coverage/capacity needed for a venue that is not possible from Macro sites alone. So it is necessary to focus on how DAS will interact with rest of the network. The coverage objective targets need to be met with holistic view of network performance. DAS performance should be on par for KPIs as defined by operators so that transition from design to optimization is as seamless as possible.
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