Interference coordination method for CSI improvement in LTE uplink with Carrier Aggregation

Abstract

Carrier Aggregation is an important feature in Long Term Evolution Advanced (LTE-A). It allows operators to provide larger operational bandwidths without the need of having a contiguous, large piece of spectrum. However, an increased bandwidth also needs a larger channel sounding to obtain channel state information (CSI), required for frequency domain scheduling and link adaptation. This constitutes a serious challenge for the uplink since wideband sounding reference signals cannot be transmitted by cell edge (power limited) users and hopped sounding requires a long time to sweep the entire transmission band, thus leading to outdated and less reliable CSI. Also, average interference and its variation in time can seriously jeopardize the CSI at the eNodeB. In this paper, we present an integration of inter cell interference coordination with CSI reporting by reducing the interference variability through controlled allocations. Results show that the entire CSI accuracy can be improved and so does the overall cell performance.