CQI adjustment for eICIC scheme in heterogeneous networks

This paper investigates the channel quality indicator (CQI) adjustment for enhanced inter-cell interference coordination (eICIC) scheme in heterogeneous networks (HetNets). In the eICIC scheme, the user equipments (UEs) in the protected cells (either small or macro cells) experience different interference levels due to the almost blank subframes (ABSs) configured at aggressor eNBs (macro or small cell eNBs). In order to reduce the signaling overhead of the CQI report for both of the subframe types, we propose to adjust the reported CQIs of the UEs in protected cells by estimating the interference from the aggressor eNBs. The CQI adjustment requirement will be determined by comparing the types of subframes where the CQI is measured and used. The interference can be estimated either with UE position information or without UE position information. The latter one is applicable only in the scenario where macro eNBs are aggressors. Simulation results show that the CQI adjustment can improve the UE performance and achieve close gain compared with the two-CQI report method.