Sounding reference signals management for CSI improvement in LTE uplink with carrier aggregation

Abstract

To assure a good channel state information (CSI) in the uplink users need to send sounding reference signals along the entire bandwidth. This task is challenging in a Carrier Aggregation framework, as the time period between two consecutive measurements will rise due to the increased available bandwidth. This leads to outdated information about the radio channels, and as a consequence a poorer link adaptation is carried out. In order to avoid this situation a inter cell interference coordination method to improve the CSI reliability is presented. This is particularly important for power limited users. On the one hand the interference variability perceived in reception is reduced by allocating resources in a controlled manner, and on the other hand by reducing the available bandwidth sounding measurements are more frequent. Results show that the entire CSI accuracy can be improved and so does the overall cell performance.