Modern wireless networks tend to employ more antennas to profit as much as possible
from MIMO techniques. But as the number of antennas increases, the problem of antenna
mutual coupling will affect the performance of MIMO systems currently operatin
g in
wireless networks such as zero forcing (ZF) and Max-SNR precoders.
This research treats the issue of mutual coupling resulting from the electromagnetic
interaction between adjacent antennas and its effect on the work of the ZF and Max-SNR
precoders in MIMO systems. The results showed a clear decrease in the performance of the
two precoders at small spacing between the antennas. It also showed the possibility of
reducing the problem of antenna mutual coupling by increasing the antenna spacing which
is not always available in MIMO systems.
The employment of multiple antennas at the transmission and reception side for the
formation of a MIMO system contributed significantly to improve the reliability of
transmission and increase the data rate. In the last decade, this system represent
ed the
backbone of wireless communications which paved the way for the development of many
techniques in this area. Therefore, there is a need to study the most important of these
techniques and compare its performance analysis.
This research deals with several closed-loop MIMO techniques : (P-OSM) which
maximizes the minimum Euclidean distance in the received signal constellation in order to
reduce the bit error rate, (X and Y Precoders) which improve the diversity gain of MIMO
system. The aim is to study and analysis the performance of previous techniques in
practical scenarios of wireless communication systems in the presence of limited feedback
channel. The results shows the possibility of practical employment of the P-OSM
technique in a simple way compared to other techniques due to its good performance and
low complexity order.
Recent years have witnessed a significant growth in wireless communication as a
result of user demand on high rates of data transmission. Therefore, there is a great
motivation for the application of MIMO systems in many modern communication
stand
ards in order to provide the required data transmission rates. Unfortunately, these
systems are sensitive to poor transmission conditions such as fading. Precoding can
improve the performance of MIMO systems to adapt with channel conditions by knowing
the full channel state information (CSI) at the transmitter. However, a full CSI is often
unrealistic in practice because of the huge amount of this information to be sent back.
Therefore, this information must be reduced and sent through a limited feedback channel.
X and Y Precoder are one of the precoding techniques that have been studied
assuming a full CSI at the transmitter. In this research, we will add a limited feedback
channel to this technique in order to become applicable in practice. The result has shown
that the loss of performance by adding a limited feedback channel may be acceptable.
