Browsing by Author "Abdulsemed, Mohammed"

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    Performance Analysis of Pilot-based Channel Estimation Techniques in Massive MIMO Systems
    (Addis Ababa University, 2020-06-15) Abdulsemed, Mohammed; Dereje, Hailemariam (PhD)
    The need for an internet connection is growing globally. So, day-by-day people need much higher data rate connection to meet their need but every physical resource in communication like frequency band, transmit signal strength are finite. Within the given limited resource, higher data speed is accomplished by a new technology called massive Multiple Input Multiple Output (massive MIMO) system. Massive MIMO fulfills the high data rate requirement through antenna diversity gain. Received signal in massive MIMO system is usually distorted by different channel effects (noise, interference, fading). In order to recover the transmitted signal correctly, channel effect must be estimated and repaired at the receiver accordingly. This is done by using different channel estimation techniques. But which one of the channel estimators should be used for a specific situation is another problem. This thesis will analyze the performance of different pilot based channel estimation techniques specifically the least square (LS) and minimum mean square error channel (MMSE) estimation methods for massive MIMO systems and based on the analysis results different discussions and conclusions are made. Furthermore, comparison among their characteristics is simulated in MATLAB and useful conclusions are given. To achieve this goal different scientific articles and MATLAB simulation results will be used. When the performance of the channel estimators was tested using the maximum ratio combining (MRC) detection algorithms, the result showed that the MMSE estimator performed better. Different comparison techniques were also run and they showed that the MMSE estimator was affected more than the LS estimator by the increase in the number of users while the increase in the number of antennas has almost the same effect on both estimators. The paper also gave possible future works in massive MIMO systems that continue from this work.