Proceedings of the 11 th ICEENG Conference, 3-5 April, 2018 54-CN 1 Military Technical College Kobry El-Kobbah, Cairo, Egypt 11 th International Conference on Electrical Engineering ICEENG 2018 An Enhanced Transport Layer Protocol for Cognitive Mobile Ad Hoc Networks Mohamed Naguib * , Yahya Mohasseb * , Hisham Dahshan * , and Ahmed Elghandour * Abstract The cognitive mobile ad hoc network is considered as a promising solution for the scarcity of wireless resources. The performance of the transport layer is degraded due to the cognitive radio characteristics like spectrum sensing and spectrum switching. This paper discusses the effects of cognitive operations on the classical TCP. A comparison between the existing transport layer protocols limitations and performances under the cognitive networks circumstances is introduced. Also, this paper proposes a flow control during the channel switching. A feedback packet to enhance the performance of TCP during the sensing period. Improvement in the throughput of the proposed protocol is shown in simulation results. Keywords Transport protocol, cogintive radio, mobile ad hoc networks, congestion window, flow control, spectrum sensing. 1. Introduction The Cognitive Mobile Ad Hoc Networks or CoMANET is an effective solution to the scarcity of the wireless resources because it enables the Secondary Users (SU) to transmit on the vacant portions of the spectrum with no impact on the primary users (PU) [1]. CoMANET have many research topics such, spectrum sensing framework to achieve maximum sensing efficiency [2], routing protocols that predicts the destination location to extend the route suitably to the new location of cognitive radio user [3], studying the impact of CoMANET characteristics over route formation and over TCP performance [4]. In the area of TCP, The well-known classical TCP approaches [5], [6], [7], suffer from poor performance over the Mobile Ad Hoc Net (MANET). The main factors that cause this poor performance are the congestion, nodes mobility and the channel uncertainty, additional factors which are caused by CoMANET such as: spectrum sensing, spectrum switching and PU’s existence [8]. * Egyptian Armed Forces.