الفهرس 
Macro diversity gainOnly 14 pages are availabe for public view
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Abstract
The 5G mobile systems promise to provide a satisfied data rate for users anywhere inside the coverage area. The mMIMO technology can provide acceptable performance for users. However, this technology is not capable of providing acceptable data rate for shadowed users and indoor ones.
The cell-Free mMIMO is an integrated version of the mMIMO technology wherein a large number of antennas is distributed over the cell. This distribution let a user have service from a lot of nearby APs.
In this thesis-: there is an attempt to enhance the performance of a cell-Free mMIMO system by deployment of relays. The mathematical formulas for SINR, SE, and EE are derived. In a cell-Free mMIMO, the existing APs are connected to a central controller and they can represent a base station. Therefore, they should be cooperated to provide a service for users. There are a lot of cooperation mechanisms. In addition, the MMSE and MRC are applied as combining schemes. The cell-Free mMIMO, based on relays, is mathematically analyzed and simulated. The cognitive radio technology is a good interference mitigation tool in wireless systems. When the cognitive technology is introduced in a relay based cell-Free mMIMO system, the performance is greatly improved as the interference is already mitigated.
In this thesis-: the relays and cognitive relays are deployed in a cell-Free mMIMO system in order to improve its performance. The simulation results display that the relay implementation can increase the EE and SE of a cell-Free mMIMO system. Moreover, the cognitive relays can greatly enhance the cell-Free mMIMO performance and the interference is already mitigated.