Channel Estimation and Precoding for Massive Mimo Downlink Time –Division Duplex System

Show simple item record Abdu, Tedros Salih 2018-02-12T09:26:38Z 2018-02-12T09:26:38Z 2018-02-12
dc.identifier.citation Abdu, 2017. en_US
dc.description Master of Science in Electrical Engineering (Telecommunication option) en_US
dc.description.abstract The massive MIMO technology uses a large number of antennas at the base station to transmit and receive signals using a Time Division Duplex (TDD) to/from users at the same time and the same frequency but with different time slot for uplink and downlink transmission. This gives a high spectral efficiency and improves reliability. In a massive MIMO downlink system the channel is estimated using uplink training by sending an orthogonal pilot sequence from users to the base station. The orthogonal pilot sequence is known at the base station and can be used to estimate the channel. This estimated channel is used to precode data at the base station for downlink transmission. Due to the coherence time limitation, the orthogonal sequence are re-used in different cells, causing the base station to receive non-orthogonal pilot sequence from adjacent cells which have an impact in estimating the channel. This channel estimation error is known as pilot contamination. In this thesis, a pre-coder technique for massive MIMO downlink TDD system is developed by considering the impact of pilot contamination in the estimating of a channel. Considering the impact of pilot contamination, a pilot reuse factor is designed to develop a novel uplink training scheme which enables an optimal estimate of the channel. The optimal estimated channel is used to develop a large scale fading precoder. A large scale fading precoding system is applied together with pilot reuse factor to mitigate the pilot contamination effect. This achieves a higher transmission rate over existing method. From simulation results obtained using MATLAB, an improvement on the 5% outage rate 10 times over the existing method has been realized. This is a significant improvement but obtained at the expense of sub-array BS installation and power consumption. en_US
dc.language.iso en en_US
dc.publisher JKUAT-PAUSTI en_US
dc.subject Channel Estimation en_US
dc.subject Channel Precoding en_US
dc.subject Division Duplex System en_US
dc.subject Massive Mimo Downlink Time –Division Duplex System en_US
dc.title Channel Estimation and Precoding for Massive Mimo Downlink Time –Division Duplex System en_US
dc.type Thesis en_US

Files in this item

This item appears in the following Collection(s)

Show simple item record

Search DSpace


My Account