Torbjörn Elfström

Spatially dependent ACLR modelling

In a multi-antenna transmitter system, the effective combined signal in the air will consist of a combination of signals. These signals will for example experience different path loss and then be combined at the receiver location. This results in a combined signal that may be different than a conducted signal at the antenna port. This model was used to investigate by how much the over the air signal and conducted signal differ at various points in space. This paper describes the work done using measurements and modelling to compare conducted measurements and over the air measurements. The investigations, and results discussed in this paper are primarily focused on Adjacent Channel Leakage power Ratio and emissions.

Considerations on establishing a measurement uncertainty framework for AAS base stations

With coming base stations using active antenna technology enabling new features such as beam forming and full dimensional Multiple Input Multiple Output (MIMO) transmission, RF characteristics such as Equivalent Isotropic Radiated Power (EIRP) and Equivalent Isotropic Sensitivity (EIS) needs to be measured Over The Air (OTA). In this contribution a method is proposed on how to determine the uncertainty of a Compact Antenna Test Range (CATR) for peak direction gain measurements for passive antennas. The uncertainty of peak direction gain for a passive antenna constitutes a major part of the uncertainty of active measurements such as EIRP and EIS.

Impact of EIRP accuracy on the predictability of throughput in LTE

With coming base station equipped with active antenna system (AAS) it is believed that the output power transmitted in the desired direction of a base station needs to be measured over the air. This in contrast to the conducted measurements performed today. The EIRP achieved by the beams radiated from a base station will affect the coverage and performance of a mobile network. The accuracy with what a base station will meet its declared EIRP in its beams may impact the predicted performance of the network and hence is an important parameter when planning a network. In this contribution we investigate how the variation of a declared EIRP affects the predictability of the performance of a mobile network. It is shown, by means of simulations, that the impact is reasonable if the EIRP variation is kept within 2.5 dB from a declared value.