Concerning the low throughput and fairness of multi-rate Medium Access Control (MAC) protocol in Mobile Ad Hoc Network (MANET), saturation throughput expressions of nodes with different rates were deduced, and the key factor to restrict performance of MAC protocol was quantitatively analyzed, which is unfairness of channel occupancy time between Slow rate Nodes (SN) and Fast rate Nodes (FN). Secondly, focusing on maximizing time fairness among different rates of nodes, two optimal methods of Contention Window (CW) and packet size were presented without affecting the throughput of SN but maximizing the throughput of FN, which makes the saturation throughput of MANET optimal. Experimental results show that, to maximize Jain fairness index when packet rates of two types of nodes are set to 1 Mb/s and 11 Mb/s, optimal values of CW in simulation and analysis are 320 and 350, respectively; similarly, values of packet size are 64 B and 60 B. Moreover, although saturation throughput value of SN basically remains unchanged, the total throughput of analysis is still 0.2-0.5 Mb/s higher than that of simulation. Therefore, throughput and fairness are both improved.

Since Mobile Ad Hoc NETwork (MANET) has imbalance of high throughput but low fairness, a novel Medium Access Control (MAC) protocol named MAC-FT was proposed. Firstly, two expressions were deduced and focus on relationship of optimal throughput and nodes' number, and relationship of idle slot probability and nodes' number. On the basis of this, idle slot probability model was developed, whose feasibility and stability were proved based on Lyapunov drift. Secondly, idle slot probability computation was implemented through Auto-Regressive and Moving Average (ARMA) model filter scheme and its dynamics was controlled by Proportional Integral Controller (PIC) model. Finally, performance of MAC-FT was analyzed synthetically. Results show that, fairness index and throughput reached to 0.98 and 6.15 Mb/s respectively, which were similar to optimal value 1 and 5.85 Mb/s. Therefore, performance of MAC-FT is better than Asymptotically Optimal Backoff (AOB), Idle Sense (IS), Distribution Coordination Function (DCF), and Gentle DCF (GDCF), and it improves balance of throughput and fairness.