Research On Technology Of LTE-Advanced Heterogeneous Network Inter-cell Interference Coordination

With the rapid development of wireless communications, higher data transfer speed and better Qos are required. Since, spectrum has become a rare resource these days; another mean is to be looked after to improve the existing wireless technology. Therefore, concept of Heterogeneous network (HetNet) has been proposed by3GPP in LTE-Advanced. In heterogeneous network, lower power nodes like Pico cell, Relay, Femto cell are deployed inside Macro cell to increase the system throughput and network coverage. But lower power nodes make the system ICIC more complicated.After CRE technology,3rd Generation Partnership Project (3GPP) LTE-A Enhanced Inter-Cell Interference Coordination (eICIC) scheme has proposed Almost Blank Sub-frame (ABS) as a solution towards the above mentioned interference problem by reducing the activity or muting the Macro sub-frame. So that the corresponding Pico/Femto sub-frame can transmit the user information without interference from Macro cell ABS. For the reason of backward compatibility ABS still transmit certain physical channel and signals like CRS, PCH, PBCH and PSS/SSS. So, interference still remains in these signals and channels. This brings new technological challenges.The main target of thesis is reducing the impact of collision of cell-specific reference signal (CRS) from Macro and Femto cell as CRS is used for channel estimation. Three schemes are researched in the thesis:IC scheme, decision-directed channel estimation scheme, IC-assisted channel estimation scheme. Interference cancelation (IC) methodology based upon RSRP is proposed in IC scheme, concludes Direct IC and Joint Detection IC. decision-directed channel estimation scheme uses DDCE methodology to estimate channel better. IC-assisted channel estimation scheme combines IC methodology and DDCE methodology, and get a better performace in channel estimation.We have developed LTE link level system model for Macro and Femto cell in the Matlab simulator. Effect of difference in power of Macro and Femto CRS on UE under different noise power is investigated. It shows, all of the schemes can get a lower bit error rate (BER) and higher throughput than performance without schemes. System performance becomes much better, and the interference of Heterogeneous network is mitigated.