Experimental Evaluation of Reference Signal Interference Canceller for Multi-BS Cooperative Transmission Control in LTE

Inter-cell interference coordination (ICIC) is attracting attention recently. In ICIC, mutual interference among cells are coordinated to mitigate strong interference to UEs, while the exchange of data signal is not necessary among eNBs, which results in lower signal processing and networking burdens compared to coordinated multi-point (CoMP) transmission. In ICIC, the interference from an eNB to UEs in surrounding cells can be mitigated by stopping signal transmission (muting) on some time or frequency radio resources. However, even when the data signal transmission is stopped, common signals such as reference signal (RS) continue to be transmitted in LTE systems. Therefore, UEs still receive the residual interference from the RS, which degrades the performance. To solve this issue, we proposed an RS interference canceller. Because the RS is a common signal, the signal can be detected and removed (cancelled) by any UE. We evaluated the effect of the canceller by computer simulation and clarified that it yields improved performance in the simple single-input single-output (SISO) antenna configuration. In this paper, we extended the canceller to the multiple-input multiple-output (MIMO) antenna configuration. We also propose a frequency-domain interference canceller, which drastically reduces signal processing cost without degrading performance. Furthermore, we implement the proposed canceller on 3GPP Release 8 LTE UE and conduct an experimental evaluation. The results demonstrate that the proposed canceller gives high performance improvement even with actual equipment.