Abstract
Keywords: MIMO, STC, HIPERLAN/2, BER, SNR, ZF, MMSE and ML.
In the early of wireless systems, a large geographic area was served by a base station with a high-power transmitter. However, a small number of users could be served by a base station and that was costly. Today, the base station divided into clusters, each cluster serves a number of users with low-power transmitters. Therefore, channel reuse and larger frequency bandwidth help to increase the number of users served. Additionally, the coverage areas by the transmitters are not the only important issue in the wireless and mobile communication systems. Besides, the data rate, the reliability and the signal-noise-ration have been considered as the additional requirements for developing the wireless systems.
Zero forcing ,minimum mean squar ,maximum liklihood equalization techniqes with succesive interfernce cansellation are used to cansel or reduce the effect of interfernce in 2*2 MIMO system. A software program using MATLAB is implemented to evaluate the proposed techniques.
A new proposed method is presented in this work to cancel or reduce the effect of the transmitted power using a feedback signal process within the transceiver MIMO unit. Several parameters including the feedback mismatch, the transmitted power, and the received power have been considered to test the performance of the system in term of the bit error rate (BER) versus signal to noise ratio (SNR). A software program using MATLAB and Simulink are implemented to evaluate the proposed method.
In addition, the MIMO system using the space time diversity introduced to the HIPERLAN/2 in which its performance is calculated in case of having perfect and imperfect feedback for different modulation schemes and different various number of radiating elements.
The results showed that the performances of the system are heavily dependent on the amount of the transmitted power, the received power, and the mismatch in the feedback. The performance of the system decreases as the feedback mismatch increases when the transmitted power and the received power are constant. At the same time, the performance of the system decreases as the transmitted power increases when the received power and the mismatch are constant. In addition, the increase in the received power enhances the system performance when the other parameters are constant.
Finally, a MATLAB code and Simulink program have been implemented to verify the results It should be noted the user has the ability to change the parameters of the transmitted power, received power, number of transmitters, number of receivers and the amount of the feedback signal mismatch