  A limitation of bandwidth in the wireless network and the exponential rise in
the high data rate requirement prompted the development of Massive
Multiple-Input-Multiple-Output (MIMO) technique in 5G. Using this method the
ever rising data rate can be met with the increment of the number of antennas.
This comes at the price of energy consumption of higher amount, complex network
setups and maintenance. Moreover a high-velocity user experiences unpredictable
fluctuations in the channel condition that deteriorates the downlink
performance. Therefore a proper number of antenna selection is of paramount
importance. This issue has been addressed using different categories of
algorithms but only for static users. In this study we proffer to implement
antenna diversity in closed loop spatial multiplexing MIMO transmission scheme
by operating more number of reception antennas than the number of transmission
antennas for ameliorating the downlink performance of high-velocity users in
case of single user MIMO technology. In general our results can be interpreted
for large scale antenna systems like Massive MIMO even though a 4x4 MIMO system
has been executed to carry out this study here. Additionally it shows great
prospects for solving practical life problems like low data rate and call drops
during handover to be experienced by cellular users traveling by high-speed
transportation systems like Dhaka Metro Rail. The cell edge users are
anticipated to get benefits from this method in case of SU-MIMO technology. The
proposed method is expected to be easily implemented in the existing network
structures with nominal difficulties.
