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Using an RF repeater as a DAS signal source with ION-E® platform

Technical paper

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Using an over-the-air (OTA) RF repeater solution always requires the RF integrator to do a proper evaluation of the RF signal levels— as well as the delays introduced by the solution.

Whenever an OTA repeater is used as a signal source with an active distributed antenna system (DAS), it is critical to have sufficient RF signal level to ensure the best optimization of the DAS. Also, the propagation delays have to be taken into account to ensure the different cellular operator services meet the desired quality requirements. Different services (voice, data) and different technologies will have specific delay requirements. The cellular carrier base station configurations will influence the delay tolerance an OTA solution can introduce. The donor node B active search window and cell range must exceed the total delay of the OTA RF repeater and DAS solution. Consulting with the cellular carrier for any additional requirements is always recommended.

To ensure performance requirements, the donor Node B active search window and cell range must exceed ttotal. In this example, assuming a 1-mile distance, in order to ensure proper operation of a DAS with ION-E and a Node A as the signal source, the Node B active search window and cell range should exceed ~32 microseconds.

Note: The 26.5 microsecond value may change depending on actual installation. This value is the maximum delay when using multimode fiber.

ttotal = 5.38 μs/mile + 26.5 μs 100m

400m

tNode

tION-E

tpropagation

tNode A = 6.0 μs

tION-E = 17.5 μs Fixed delay from RFD to UAP, excluding cable delay

tMM Fiber = 2.0 μs Delay of 400 meters of multimode cable—can be lower

with less cable or higher if longer lengths of singlemode fiber are used.

tCat6A = 0.5 μs Delay for 100 meters of cable—maximum delay possible.

t40m air = 0.15 μs Propagation delay from UAP to UE.

tmisc = 0.35 μs Miscellaneous delay of other elements, such as

donor coaxial cables.

tpropagation = 5.38 μs/mile (3.33 μs/km)

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TP-109308.1-EN (04/17)

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