# Building Realistic Mobility Models for Mobile Ad Hoc Networks
## 2 Literature Review
### nS-2 and nS-3 in Mobile Ad Hoc Network Research  
ns-2 has been used extensively in MANET research, and it is a _\"popular discrete-event network simulator... which remains in active use and will continue to be maintained\"_ ([[https://www.nsnam.org/support/faq/ns2-ns3/](https://www.nsnam.org/support/faq/ns2-ns3/)]([https://www.nsnam.org/support/faq/ns2-ns3/](https://www.nsnam.org/support/faq/ns2-ns3/))). Several early examples include the following: ns-2 extensions to model the MAC and physical layers of 802.11 ([PERSON] et al., 1998, [75]); ns-2 with Monarch extensions to compare Dynamic Source Routing (DSR) and Ad hoc On-Demand Distance Vector (AODV) ([PERSON] et al., 2001, [76]); and ns-2 with protocols codes to compare location aided routing (LAR) with the distance routing effect algorithm for mobility (DREAM) ([PERSON] et al., 2002, [77]). To reiterate, [PERSON] et al. (2005) [66] report that 43.8% of papers published in the ACM's MobiHoc conferences from 2000 to 2005 used ns-2, followed by the next most popular simulator GloMoSim (10%). ns-2 has been identified as the de facto standard for network simulation ([PERSON] et al., 2006, [74]). [PERSON] and [PERSON] (2007) [78] employ ns-2 in their investigation of opportunistic delivery protocols in delay-tolerant networks. However, ns-2 is found to be too slow when involving large numbers of nodes (in their case, over 5000 nodes) and has provided more than enough necessary details at the lower network layers. However, this contradicts with the research conducted by [PERSON] and [PERSON] (2012) [79], which maintain that ns-2 does not provide enough details or sufficiently accurate models of the wireless communication layers. [PERSON] et al. (2007) [80] compare the effects of various mobility models on the DSR ([PERSON] and [PERSON], 2007, [81]) and Destination-Sequenced Distance Vector (DSDV) ([PERSON] and [PERSON], 1994, [24]) routing protocols, using ns-2 developed and extended for the Monarch Project (nS2, nd). [PERSON] and colleagues (2010) [82] use ns-2 to evaluate their new secure Geocast solution. [PERSON] et al. (2012) discuss an implementation, which adds on a module for ns-2 to provide more realistic mobility models. Further examples include [PERSON] et al. (2013) [83] looking at high mobility vehicular ad hoc networks, [PERSON] et al. (2013) [84; 85] considering connectivity in disaster response, and [PERSON] and [PERSON](2012) [86] evaluating their VANET routing protocol, Reliable Inter-Vehicular Routing (RIVER). ns-2 is so commonly used and so well-known in MANET research that many papers merely state that it has been used with no discussion or justification at all.  
The ns-3 (an antecessor of ns-2) is a discrete-event network simulator for internet systems that can be connected to the real world and used as a real-time emulator (ns3, nd), a feature that is not inherent in ns-2. Many comparisons have been made between ns-2 and ns-3 (i.e., [PERSON] and [PERSON], 2015, [87]; [PERSON] and [PERSON], 2016, [88]; and [PERSON] et al., 2017, [89]), where the latter improves on the following aspects: code efficiency, modularity and scalability, modelling so that it is close to realism, model reuse, support for virtualization, increased reliability, etc. It, however, has its limitations, such as limited scope for virtualization and complexity. A list of ns-3 MANET simulation-related projects has been presented by NS 3 Simulations (nd) [90]. Examples of ns-3 and MANET research are performance comparison (e.g., packet receiving rate analysis, packet delivery ratio, throughput, routing overhead, average end-to-end delay, etc.) and evaluation of MANET routing protocols, such as Ad hoc On-Demand Distance Vector (AODV), Destination-Sequenced Distance Vector (DSDV), Optimized Link State Routing (OLSR), and Dynamic Source Routing (DSR) ([PERSON] et al., 2013, [91]; [PERSON] et al., 2014, [92]; [PERSON] and [PERSON], 2014, [93]; [PERSON] and [PERSON], 2015, [94]; [PERSON] and [PERSON], 2016, [95]; [PERSON] et al., 2017, [96]; and [PERSON] et al., 2017, [97]);