sorry for the delay, only afterwards I realized that you indicated the version in the first place.
The SINR averager is utilized in the link adaptation which is done within the scheduler. In +network_elements/lteScheduler.m there are three feedback functions implemented; link_adaptation_SIxO, link_adaptation_MU_MIMO and link_adaptation_CLSM. These calculate an post equalization SINR and an effective SINR which is then mapped to a CQI value for link adaptation. Within this calculation the SINR_averager is utilized to average the post-equalization SINR. In the default setting this averager is the harmMeanAverager.