Research On The Improvement Of Reference Signal Design And Channel Estimation In LTE-A

LTE-A is the continued evolution of LTE, the target of which is to meet the IMT-Advanced requirements in ITU-R and maintain backwards compatibility with LTE simultaneously. The most basic features of LTE-A is to support higher data rate. Carrier aggregation and higher-order MIMO are considered to be the two main technologies to achieve higher peak rates in LTE-A.As carrier aggregation technology is adopted to extend the largest system transmission bandwidths, for downlink (DL) transmission, according to LTE release 8 technology specification, all the aggregated component carriers (CCs) in a cell will have the same cell identifier (ID), which may increase the Peak-to-Average Power Ratio (PAPR) or cubic metric (CM) values of the DL signals. To use distinct cell ID per DL CC to generate DL reference signal (RS) sequence can mitigate this problem but will cause some other issues on the corresponding uplink carrier. In this thesis, two approaches based on same cell ID allocation in all the aggregated CCs are proposed to solve the problem of high CM/PAPR and can also keep the channel estimation performance.For enhanced MIMO technology with up-to eight antenna ports in LTE-A DL transmission, RS overhead will increase significantly if RS generation method of LTE release 8 technology specification is adopted, leading to a decline in spectral efficiency. In this thesis, a kind of demodulation RS (DM-RS) pattern is designed for rank lower than 8 on the basis of DM-RS pattern for rank lower than 4. In addition, a set of over cover code is designed. Simulation results show the good performance of the designed DM-RS pattern on channel estimation.