TCP Performance in Wireless multi-hop Networks

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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)
  • Performance Metric

    Measurement of TCP-Reno Throughput

    Mobility Induced Behaviours

    TCP Performance Using Explicit Feedback

    Split-TCP

    Conclusion

    References