Prevailing techniques for effective channel access in flying ad-hoc networks

Flying ad-hoc network (FANET) plays a crucial role in almost all realm of human life due to its access to internet along with high mobility. The main factors that account for designing an excellent flying ad-hoc network involves, high throughput, congestion and collision avoidance, energy efficiency, low end-to-end delay, channel utilization etc. Depending upon the scenarios whether it be a rescue mission or weather monitoring, where Unmanned Aerial Vehicles (UAV) are employed, specific protocols are required to enhance the performance. To aid the dynamic and mobile nature of UAVs in FANETs, various Medium Access Control (MAC) protocols are developed based on requirements. MAC protocols are classified into contention-based, contention-free and hybrid domains, on the basis of how the channel is accessed. Hybrid protocols are more powerful than the other two categories as it combines the advantages of both domains. This paper aims to provide an extensive study of the most recent hybrid protocols along with their strengths and weakness. Regarding this, the existing survey papers are discussed to reveal their findings towards the designing of MAC protocols. Different aspects including methodologies, objectives, assumptions, achieved enhancements, limitations, are covered. Furthermore, the research gap in this field is discussed.