Ethersim: a simulator for wireless and mobile networks

The paper describes Ethersim, a simulation tool to model and study the performance of integrated service networks that provide multimedia (audio, video, data) information access to mobile users carrying portable wireless terminals and hosts. The design process of such networks requires a proper understanding of how network and multimedia application performance is affected by (i) the choice of algorithms and protocols at various network layers, (ii) the wireless link characteristics, (iii) the presence of mobile hosts, and (iv) the host mobility patterns. Ethersim has been built using a discrete event based simulator core and incorporates models of user applications and transport, network and MAC layer protocols. It provides the capability to specify network topology and host mobility patterns. The software architecture of Ethersim employs five special entities: an air module, a map, a mover, mobile hosts, and basestations. The air module models the physical air-interface effects (e.g., RF power decay, frequency collisions etc.). The mover is a central entity that moves the mobile hosts on the map. Ethersim allows for both random and goal-directed movements of mobile hosts, and also allows synchronized goal-directed movements to model conference room type mobility patterns. We also present case-studies of using Ethersim to model and study the interaction of transport layer, connection rerouting protocol, and radio characteristics in a mobile and wireless ATM network at Bell Laboratories.