Advanced Receiver Algorithms for LTE Downlink

The reception of the PDSCH at the UE of the LTE downlink is investigated in the presence of inter-cell interference. The noise plus interference covariance matrix is used in the MMSE equalization to suppress the effects of interference. PDSCH can be transmitted using one of several possible Transmission Modes (TM). The thesis focuses on TM2 and TM4 with rank 1, whereby only the case of two transmit antenna ports and two receive antennas is considered. In case of TM2, the transmitter (eNodeB) employs Alamouti SFBC for transmit diversity. In case of TM4 with rank 1, the eNodeB applies a precoding to the PDSCH symbols for transmissions with two antennas. Some characteristics of the interference and their impact on the equalization of the desired signal are described. several methods to estimate the noise plus interference covariance matrix are discussed and evaluated in the thesis. A new method is suggested to enhance the estimation accuracy of the covariance matrix. Regularization of the noise plus interference covariance matrix is suggested for the case of low interference-to-noise power ratios.