Cooperative MAC Protocol With Optimal Relay Selection Algorithm for UAVs Ad Hoc Network in Disasters

After the natural disasters, establishing a reliable and resilient emergency communication network is crucial, particularly when conventional infrastructure, such as base stations fail. Flying Ad Hoc Networks (FANETs) that leverage multiple unmanned aerial vehicles (UAVs), offer a superior alternative to single UAVs by enabling dynamic, cooperative communication (CC) that extends operational range and enhances mission capabilities in disaster zones. Cooperative transmission improves communication reliability and data rates while reducing delays by mitigating wireless channel impairments due to mobility in FANETs. Selecting the optimal relay is crucial in cooperative communication, as it can significantly enhance both communication reliability and overall system efficiency. The primary contribution of this work is the development of a cooperative MAC protocol with an optimal relay selection algorithm tailored for FANETs in disaster scenarios. This algorithm, incorporating a utility backoff process, is built on a realistic network model that accounts for SNR, distance, and mobility. The random-access approach was adopted due to the limitations of IEEE 802.11 standards in supporting cooperative communication. Consequently, new control packets were developed, and existing control formats were revised to enable effective cooperation. To evaluate the proposed protocol, an analytical Markov Chain model was developed and validated through simulation. Performance-influencing parameters were considered, and relationships between various parameters and performance metrics were analyzed, including different fading channels, bit error rates and system outage probability. The numerical results show that the protocol significantly enhances performance by increasing throughput, enhancing communication reliability through reduced packet dropping rates, and decreasing transmission delays.