10.3 Impact of Noise Power
An active DAS consists of amplifiers and, depending of the actual configuration, will have a given noise figure that adds to the noise on the UL of node B.
10.3.1 The UL Noise Increase on Node B
The active DAS needs to be configured so that the active DAS and UL attenuators are set at optimum values, minimizing the resulting noise increase on node B – without degrading the performance of the UL. However there will be a noise increase on the UL of node B. Therefore, it is crucial to tune the admission control parameter, with regards to the added noise power on the UL of the node B
This includes the noise increase caused by the active DAS (minimized by a correct UL attenuator). If this is not tuned, the result will be that the admission control assumes too high a UL traffic (noise level), limiting the UL capacity. In extreme cases (if no UL attenuator is used), this results in no call set-up in the cell.