Thus, in a multicell environment to fully exploit the multiple antenna gain, base station (BS) cooperation is required.
Therefore, the benefit of multiple antenna gain is hardly harvested, and that is one of the challenges for massive MIMO applied under HSR scenario.
Since the viaduct raises the height of transmit antennas leading to a relatively clear line-of-sight (LOS) and few scatters [24], the benefit of multiple antenna gain is barely harvested.
It has been proved that multiple antenna systems provide higher gain in capacity without increasing the use of spectrum, reliability, throughput, power consumption and less sensitivity to fading, therefore leading to high data rates of wireless communication systems, which is the most sorted outcome of all research work.
A single antenna receiver: although the usage of multiple antenna receivers could introduce additional performance gains, it was chosen to adopt the single antenna approach.
Numerical results demonstrate that the precoder can get rid of all the interference present in the system and benefit therefore from the diversity and power gains achievable with multiple antenna systems.
In fact, as the gain of using multiple antenna UEs is mainly due to the IRC which cancels ICI, the benefits of increasing N are seen more in a non-cooperative scenario, where the residual ICI is higher with respect to DC.
Motivated by the rapid growth of wireless applications with multiple antenna terminals, multiple input multiple output (MIMO) relaying has gained much attention now a days due to its improved data rate, coverage extension and improved signal to noise ratio (SNR).
Note that if multiple antenna elements are collocated at one RRU, then the corresponding large-scale channel gains are equal.
In parallel, multiple antenna techniques (MIMO) can improve the spectral efficiency of wireless communication systems and provide significant throughput gains.
