Key Techniques Of Lte Base Station Family Interference Suppression

Global System for Mobile communications statistics show that in mobilecommunications services about50%of the telephony services and70%of the dataservices take place in the indoor environment. Given that high frequency wirelesssignals’ wave-length are short and have a poor performance of the building penetration,the outdoor macro base station signal is difficult to cover the indoor envirementeffectively. With the Femtocell technology program invented, the problem of the macrobase station deep indoor coverage is properly solved.However, the femtocell and the macro base station are facing the same problems overthe interference. In the communication scene of multiple receiving antennas, theantenna diversity technique is the most one being used among the anti-interferencetechnologies. There is some literature comparing three combined approach, IRC, MRCand EGC of the output SNR in the interference limited scenarios, while the output SNRof the IRC method is the highest. Meanwhile, the literature also pointed out that thecovariance matrix of interference in the IRC method is not easy to obtain. In this paper,I make a research of the IRC method against the Femtocell’s interferences.Against the interference noise covariance matrix estimation problem, this articleproposes a new multi-antenna merger: the interference reconstruction rejectioncombining. Firstly, estimate the covariance matrix of the received signal, and take it asthe approximation of the interference signal covariance matrix; Secondly, restore thedesired signal with the application of Interference Rejection Combining; Thirdly,remove the desired signal from the received signal and abtain the Femtocell’sinterference; Lastly, estimate the covariance matrix of the interference signal again, andcomplete the interference rejection combining.Against the problem of the time-frequency interference noise covariance matrix anddiagonal loading, this paper proposes a new method based on estimates of diagonalloading: Firstly, perform interference and noise covariance matrix for simpletime-frequency domain correlation; Secondly, use the diagonal loading to improve therobustness of the matrix; Thirdly, perform the interference suppression combination.This article makes simulation and analysis of the two methods mentioned above.Compared with the traditional IRC method, the IRRC method proposed in this paperhas a improvement of1.5dB transmitted-power when BER=0.01, the DL-IRC methodhas a improvement of2.5dB transmitted-power when BER=0.02. The methodsproposed in this paper can be widely used in the LTE uplink receiver, which has acertain reference value on the realisation of the receiver technology.