| Channel estimation is an important part for the design of receivers in mobile communication systems. In order to recover the transmitted information correctly, the effect of the channel on the transmitted signal must be correctly estimated. In this thesis, the pilot based channel estimation algorithms for 3GPP LTE downlink is studied.;Channel estimation algorithms such as Least Square (LS), Minimum Mean Square Error (MMSE) and Modified MMSE (M-MMSE) channel estimation algorithm have been evaluated for LTE downlink 5 MHz bandwidth configuration. The performance of these algorithms for Block type and Comb type pilot arrangement has been measured in terms of Bit Error Rate (BER). For Comb type pilot arrangement, the performance of Linear Interpolation (LI), Spline Cubic Interpolation (SCI) and Low Pass Interpolation (LPI) methods have been compared. Though higher order interpolation is used for better interpolation accuracy, the improvement in performance is not proven for all cases and for some cases Linear Interpolation can give better performance. For cases when the subcarrier spacing is very small compared to the coherence bandwidth which is a result of small delay spread, Linear Interpolation can give better performance in terms of BER. The ITU outdoor to indoor and pedestrian test environment channel model A, which has a small R.M.S. delay spread of 45 ns, has been used for all simulations. The performance of Comb type pilot arrangement with different pilot spacing has also been compared. |
