Mostafa M. Fouda's research while affiliated with Idaho State University and other places

Pattern synthesis is widely used in many radar and communication systems and received great interest. So, this paper proposes a new beamforming strategy based on a hybrid combination between grey wolf optimizer (GWO) with L2-norm called proposed GWO. This approach is applied to synthesized uniform linear arrays (ULA), Chebyshav arrays, and shaped pattern arrays. Moreover, it is utilized for side lobe level (SLL) and size reduction of antenna elements. In this strategy, the GWO is utilized to optimize the element spacing to adjust the half-power beam-width (HPBW) to save it the same as desired pattern. Furthermore, the excitations of the antenna elements are optimized via the L2-norm minimization problem. The proposed GWO has low complexity (fewer iterations and computing time) compared to other algorithms. In addition, it has a very accurate approximation of the original radiation pattern. As well, the computer simulation technology (CST) microwave package is utilized to achieve the practical validation of the proposed methodologies. As an application of the proposed GWO, it is employed to create a proposed hybrid beamforming (PHB) structure for Multi-input Multi-output (MIMO) systems. Consequently, the BS transmitting antennas are synthesized for gain maximization while utilizing the current amount of antenna elements. This results in considerable savings in antenna components and associated radio frequency (RF) chains which reduces system complexity. Furthermore, array gain maximization will increase the received signal-to-noise ratio (SNR). In addition, the SLL reduction scenario will decrease the interference from undesired users which in turn will also increase SNR. Hence, the performance of the system in terms of spectral efficiency (SE) and power utilization will be improved.

In this paper, re-configurable intelligent reflecting surfaces (IRS) based on cell-free communications to serve multi-user (MU) are considered. This is to enhance the transmission for the next generation of wireless communications. This technique has witnessed lots of interest recently due to its ability to increase diversity gain, especially in the presence of obstacles between the users and the service providers. The IRS contains low-cost and large-scale reflection elements that work passively to guide the electromagnetic waves toward the direction of interest. These re-configurable meta-surface cells have reflection coefficients that can be adjusted by changing their phase shift to enhance the desired signal of interest and apply interference mitigation. Moreover, the IRS can be exploited to improve the overall sum rate throughput and reduce outage probability. The proposed system considers a transmission between multiple base stations (BSs) that equipped with multiple antennas and several single antenna users through an IRS in the presence and absence of a traditional path between them. Optimization techniques are employed to select the optimum beamforming precoders and to control the IRS’s phase shifts by steering the incident signals toward the intended users. Furthermore, an off-the-shelf power allocation optimization approach, called Polyhedron, is exploited to enhance the overall spectral efficiency (SE) and energy efficiency (EE) of the proposed system and reduce the required transmitted power. The proposed system with the suggested optimization approaches demonstrates significant improvement in the SE with a considerable reduction of the entire transmitted power by all BSs especially when increasing the number of antennas at the BSs along with using a higher number of IRS’s reflected elements.