In this paper, we present a new MAC (Medium Access Control) protocol, called Hybrid ALOHA (H-ALOHA), which is a combination of two existing protocols: Pure ALOHA (P-ALOHA) protocol and Slotted ALOHA (S-ALOHA) protocol. The idea behind it is to design a MAC protocol that could meet some specific requirements in wireless networks, such as reducing energy consumption, delay minimization, and increasing the throughput. To the best of our knowledge, the S-ALOHA protocol is an improved version of P-ALOHA. However, during one single transmission scenario, P-ALOHA works better than S-ALOHA in terms of energy consumption and packet delivery. Motivated by that fact, we combine these two protocols, resulting in a hybrid ALOHA. A finite-state Markovian model is proposed to study the steady-state performance of H-ALOHA including normalized throughput, backlogged throughput, access delay, backlogged delay, and energy consumption. The proposed hybrid protocol has been compared with the S-ALOHA protocol. The simulation results show that the proposed hybrid protocol outperforms all ALOHA protocols. On average, the proposed protocol outperforms the S-ALOHA protocol by 60% in terms of normalized throughput, by 15% in terms of access delay, and by 23% in terms of total energy consumed during the transmission process.

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Information from COVID-19 IoT (Internet of Things) devices is greatly important when it is fresh. However, the packets' collision problem slows down the speed at which this information reaches, resulting in a wider spread of the virus. In this paper, we address this challenge by giving priority to COVID-19 IoT devices over consumer IoT devices. We propose a two-dimensional Markov chain for modelling the IoT network including COVID-19 IoT devices, then we derive the performance metrics. Our numerical results show a significant improvement in the performance of COVID-19 IoT network in terms of throughput and average delay. Our approach provides a reliable and fast wireless connection of COVID-19 IoT devices to the gateway.