Effects of wireless physical layer modeling in mobile ad hoc networks

TLDR

Most MANET studies use simulation models to evaluate devices and protocols, but they usually focus on higher‑layer protocols and overlook interactions with physical‑layer models. The paper aims to identify the physical‑layer factors that influence higher‑layer protocol performance. The authors analyze signal reception, path loss, fading, interference, noise, and preamble length, comparing ns‑2 and GloMoSim physical‑layer models and quantifying their impact on routing protocol evaluations. Experiments reveal that physical‑layer factors alter absolute protocol performance and can change the relative ranking of protocols in the same scenario.

Abstract

In most studies on mobile ad hoc networks (MANET), simulation models are used for the evaluation of devices and protocols. Typically, such simulations focus on the specific higher layer protocols that are being proposed, and tend to ignore details of models at other layers, particularly the interactions with physical layer models. In this paper, we present the set of factors at the physical layer that are relevant to the performance evaluations of higher layer protocols. Such factors include signal reception, path loss, fading, interference and noise computation, and preamble length. We start the discussion with the comparisions of physical layer models in ns-2 and GloMoSim, two commonly used simulators for MANET studies, and then quantify the impact of the preceding factors under typical scenarios used for the performance evaluation of wireless ad hoc routing protocols. Our experimental results show that the factors at the physical layer not only affect the absolute performance of a protocol, but because their impact on different protocols is non-uniform, it can even change the relative ranking among protocols for the same scenari