TCP Performance in Wireless multi-hop Networks

Introduction

Early research showed TCP suffers poor Performance in wireless networks because of packet losses and corruption caused by wireless inducted errors Further studies searched for mechanism to improve TCP performance in cellular wireless systems Other researches investigated other network problems that negativly affect TCP performance, such as bandwidth asymmetry and large round trip times, which are prevalent in satelite networks During the presentaition we adress another network charackteristic that impacts TCP performance, which is common in mobile ad hoc networks: link failures due to mobility First present performance analysis of standart TCP over mobile ad hoc networks Then present analysis of the use of explicit notification techniques to counter the affects of link failures

Simulation Environment and Methodology

For simulations the ns network simulator from Lawrence Berkles National Laboratory was used, with extensions from the MONARCH project at Carnegie Mellon Extensions include a set of mobile ad hoc network routing protocols, an implementation of BSDs ARP protocol, an 802.11 MAC Layer, a radio propagation model and mechanisms to model node mobility using pre-computed mobility patterns that are fed to the simulation at run time No modifications were made to the simulator (accept minor bug fixes that were necessary) All results based on a network configuration consisting of TCP-Reno over IP on an WLAN, with routing provided by the Dynamic Source Routing (DSR) protocol and BSDs ARP protocol (used to resolve IP adresses to MAC adresses)