An approach is presented to enhance the isolation of a two-port Multiple Input Multiple Output (MIMO) antenna using a decoupling structure and a common defected ground structure (DGS) that physically separates the antennas from each other. The antenna operates in the 24 to 40 GHz frequency range. The innovation in the presented MIMO antenna design involves the novel integration of two arc-shaped symmetrical elements with dimensions of 35 × 35 × 1.6 mm³ placed perpendicular to each other. The benefits of employing an antenna with elements arranged perpendicularly are exemplified by the enhancement of its overall performance metrics. These elements incorporate a microstrip feed featuring a quarter-wave transformer (QWT). This concept synergizes with decoupling techniques and a defected ground structure to significantly enhance isolation in a millimeter wave (mm wave) MIMO antenna. These methods collectively achieve an impressively wide bandwidth. Efficient decoupling methodologies have been implemented, yielding a notable increase of 5 dB in isolation performance. The antenna exhibits 10 dB impedance matching, with a 15 GHz (46.87%) wide bandwidth, excellent isolation of more than 28 dB, and a desirable gain of 4.6 dB. Antennas have been analyzed to improve their performance in mm wave applications by evaluating diversity parameters such as envelope correlation coefficient (ECC) and diversity gain (DG), with achieved values of 0.0016 and 9.992 dB, respectively. The simulation is conducted using CST software. To validate the findings, experimental investigations have been conducted, affirming the accuracy of the simulations.

Wheel-based network resilience passive optical network (PON) based on mode division multiplexing (MDM) can be integrated with optical code division multiple access (OCDMA) schemes efficiently for the fixed and backhaul traffic under normal and break/failure fiber operating conditions. In this work, a bidirectional 10/2.5 Gbit/s hybrid MDM-OCDMA-PON system using multi-weight zero cross-correlation (MWZCC) code is proposed. Donut modes 0 and 1 are incorporated by the MDM technique in the proposed system. The benefit of this work is to offer an inexpensive, high-bandwidth and advanced long-haul network with satisfactory resource utilization ability for fiber links with protection against faults and to improve the reliability along with survivability of the network. The simulation results show the successful realization of the multimode fiber (MMF) link at 1.6 km in the uplink and 1.2 km in the downlink directions under an acceptable bit error rate (BER). The minimum accepted received power of −31 dBm in uplink and −27 dBm in downlink over 1 km link at 10/2.5 Gbit/s rate is obtained. Moreover, the minimum received power of −20 dBm in uplink and −30 dBm downlink is achieved by using MWZCC code compared to other codes handling 58 simultaneous end users. Further, the influence of fiber impairments and connected devices on the proposed approach is numerically evaluated. Moreover, it is shown that the wheel based proposed approach performs well than other topologies for the bidirectional network resilience transmission.