Intelligent reflecting surfaces (IRS) are considered one of the prominent technologies to be adopted in 6G and beyond networks. However, one of the main IRS limitations is restricting the communication to the reflective dimension, which means that users located behind the IRS surface cannot benefit from it. In this paper, we make use of intelligent omni-surfaces (IOS), as an alternative to IRS, in addition to unmanned aerial vehicles (UAV) to achieve secure communication in an Internet-of-Things (IoT) communication system. Specifically, we propose IOS-UAV assisted communication wherein an access point (AP) tries to send confidential information to a legitimate IoT device in presence of an eavesdropper. The UAV serves two fold; it acts as a friendly jammer that is trying to degrade the signal quality at the eavesdropper and as a source of energy to power up the IoT device via simultaneous wireless information and power transfer (SWIPT) to address the limited power available to it. We formulate an average secrecy rate maximization problem, which jointly optimizes the AP and UAV transmission powers, the UAV trajectory, IOS phase shifts and power splitting factor. The formulated problem is non-convex, therefore we exploit successive convex approximation (SCA) to tackle this issue. Simulation results show that the iterative SCA solution converges rapidly. Besides, the proposed scheme outperforms the traditional system without IOS by a gap of 140% in terms of the secrecy capacity.INDEX TERMS Intelligent omni-surface, unmanned aerial vehicle, simultaneous wireless information and power transfer, physical layer security, Internet of things, successive convex approximation.

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Recently, many routing protocols have been implemented to accomplish progress in the energy consumption field for data collecting wireless sensor networks. Owing to the existence of many drawbacks for employing a static sink, this study utilises the idea of moving the sink node to achieve amelioration in energy utilisation and provide longer network lifetime. The idea of the proposed protocol depends on combining the mobile sink improved energy-efficient power-efficient gathering in sensor information system-based routing protocol (MIEEPB) with the direct transmission (DT) protocol to utilise the limited energy of wireless sensors efficiently. As the motorised movement of the sink is operated by petrol or electricity, the data loss through the transition of this sink from its current location to the next location must be diminished by restricting the moving distance. In the proposed protocol, the mobile sink must spend at least a certain amount of time (sojourn time) at each of its sojourn locations to avoid overhead. Extensive analysis was implemented on the proposed protocol (called MIEEPB-DT) to appraise and compare it with MIEEPB and DT. Simulation results show that the proposed MIEEPB-DT protocol gives better improvement in energy efficiency and network lifetime than both MIEEPB and DT.

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