# Estimation of the Achievable Performance of Mobile Ad Hoc Networks with Optimal Link State Routing
###### Abstract
Simulation models by their nature cannot provide an accurate description of the network, especially the node mobility behavior and the characteristics of the wireless environment [22]. Network emulation is performed in real-time and brings the network model closer to the real system by combining actual elements of the deployed network implementation with other modelled components [22]. Testbeds use a full set of real components, so the methods of testing network scenarios on a testbed provide the most realistic research results. Recently, when building MANET testbeds, it was suggested to use a universal experimental platform [22; 28]. Usually, such a platform is based on a modular architecture, has sufficient versatility, and can be flexibly used to investigate different scenarios of experiments. One of the actively developing areas in the MANET field is also the development of new routing algorithms based on the predicted location of nodes [22; 29]. Such algorithms are expected to be used in specialized networks mainly with rather fast node movement, such as the Vehicle Ad hoc Networks (VANETs) or the special case where vehicles are unmanned devices, the Unmanned Vehicle Networks (UxVs) [22]. In spite of the development of new routing protocols, many research works aimed at improving OLSR continue to appear. For example, an improved OCI-OLSR protocol (Optimized-Control-Interval-Optimized-Link-State-Routing) is proposed in [30], which focuses on better control interval management, enhanced MPR process selection, reducing neighbor hold time, and decreasing flooding. In [31], the multipath heterogenous ad hoc network OLSR (MHAR-OLSR) protocol is described and investigated. MHAR-OLSR is an OLSR extension with new functionalities: nodes' identification, paths' calculation, paths' classification, and paths' choice, designed for heterogeneous ad hoc networks composed of MANET, VANET, and FANET devices. Once again, we note that for networks in which the change in node position is quite slow (no faster than the average packet transmission time from source to destination) in most cases, the OLSR protocol or its modifications are used. Thus, in [30], the number of research papers with the keywords \"OLSR\" and \"MANET\" is given. This paper studies the research trends of the OLSR routing protocol in MANETs and analyzes numerous advantages of OLSR (low packet delay, ability to work in high-density networks, much higher performance compared to other protocols, etc.). It has been shown that in the time period from 2002 to 2022, the number of research papers on the use of OLSR in MANETs is steadily increasing [30]. Therefore, in this paper, OLSR is selected as the routing protocol for the study. In practice, there is often a need to quickly evaluate, without simulation, the potential capacity of MANETs to carry traffic corresponding to different classes of service without the detailed definition of all network parameters. In particular, it is of interest to determine the number of nodes or the possible coverage area that can provide, for example, an acceptable packet delay. This problem can be solved by evaluating the \"internal\" network efficiency metrics proposed in [1; 26]. This paper presents analytical expressions for calculating the maximum achievable values of quality metrics for different scenarios of packet transmission in the network using selected routing and Resource Reservation Protocols, assuming no packet collisions in nodes. The obtained estimates allow us to formulate upper limits and constraints on the number of nodes and network scalability for different scenarios of both indoor and outdoor node deployment. The results of the study can form the basis of a methodology to enable the \"conscious\" or rational selection of MANET parameters for further simulation, network emulation, or testbed experiments under specific operational scenarios or environmental conditions. The remainder of the paper is organized as follows.