# On the Fidelity of NS-3 Simulations of Wireless Multipath TCP Connections
## 2 Related Works  
The ns-3 simulator [7] was introduced in 2008 as a successor for the ns-2 simulator. However, ns-3 is not backward compatible with ns-2. Ns-3 is entirely written using C++ and supports python scripting, whereas ns-2 is partly written using C++ and partly using TCL scripting language. One of the major advantages of ns-3 over ns-2 is that the ns-3 supports the direct code execution feature, which allows the simulator to use real applications without code change. Moreover, ns-3 has been designed to be easily integrated into real testbeds and virtual machine environments [11]. The ns-3 simulator has been gaining popularity among researchers since its advent. Currently, it is widely adopted, as documented in [12]. A significant number of MPTCP research works depend on the ns-3 simulator. In the research articles [13; 14; 15; 16], the authors propose implementations of MPTCP in ns-3. Some of these MPTCP implementations have been used to study MPTCP performance as in the sequel. The authors of [17] evaluate the impact of various packet reordering solutions on the throughput performance of MPTCP over different congestion control algorithms using ns-3 simulations. [PERSON] et al. propose a new congestion control approach to improve the MPTCP performance in data center networks. They utilize the ns-3 simulator to evaluate the goodput performance of MPTCP with the proposed congestion control method. In order to improve the performance of short flows in MPTCP, the authors of [18] propose a flow-based transmission optimization algorithm for MPTCP. They validate the proposed algorithm using ns-3 computer simulations. The authors of [19] analyze MPTCP in a cooperative relay-based LTE network and propose some extensions to MPTCP to guarantee a stable throughput. They validate the proposed model using the ns-3 simulator (LTE/Wi-Fi ns-3 models and implementation of MPTCP is used). Since the addition of DCE functionality in ns-3 [10], some researchers have been able to exploit the Linux kernel implementation of MPTCP in ns-3 [20]. The authors of [21] utilize ns-3 DCE (Linux MPTCP) to analyze the effect of path characteristics (RTT and bandwidth) and packet scheduling policies on the throughput performance of MPTCP. [PERSON] et al. evaluate the throughput performance of MPTCP under varying factors such as bandwidth, delay, and frame error rate using ns-3 DCE. An analytical model to calculate the MPTCP throughput and latency is proposed and validated using ns-3 DCE in [22]. Other researchers leverage the LENA module (LTE) [8] and the Wi-Fi modules [23] of ns-3 to build a multipath heterogeneous wireless network environment. In [24], the authors analyze the throughput performance of MPTCP in a heterogeneous wireless network of LTE and Wi-Fi, where a Wi-Fi subflow experiences multiple handoffs. They propose congestion control strategies suitable for the handoff scenario and validate the proposed method using ns-3 DCE. The authors of [25] employ ns-3 DCEto evaluate their proposed software-defined networking (SDN) approach to improve fairness among single-path flows and MPTCP multipath flows (LTE and Wi-Fi). An MPTCP-based mobility support scheme for LTE networks is developed in [26]. The authors claim that the proposed solution enables seamless traffic continuity after a handover with serving/packet gateway relocation and validate this using ns-3 DCE. [PERSON] et al. [27] propose a scheduler for MPTCP in SDN. They claim that the proposed scheduler improves throughput performance and minimizes the cost for users, according to the conducted ns-3 DCE simulations. As MPTCP is expected to play a significant role in the 5G networks, researchers have started to focus on MPTCP with mmWave networks. [PERSON] et al. provide a performance evaluation of single-path TCP and MPTCP with mmWave links using ns-3 DCE [28]. Recently, another multipath-based protocol named multipath QUIC was introduced [29], but to the best of the authors' knowledge, no ns-3 implementation is available yet for this protocol.