Contributions to IP-based wireless communications
Sammanfattning: The introduction of IP-based communications in wirelesssystems posed several research issues. In this thesis, wepresent different contributions to address some of the issuesin terminals and radio access networks. Firstly, we look atapplication adaptation to varying levels in quality of service(QoS). We describe a terminal architecture called BRENTA inwhich mobility is supported at the IP layer and therefore it isnot noticeable by applications except for a possible QoSvariation. BRENTA transport layer is enhanced with QoS supportto deal with these variations. Applications specify their QoSrequirements via the Extended Socket Interface. The ExtendedSocket Layer maps application requests to network QoS schemes.In this way, roaming between networks with different QoSarchitectures, such as DiffServ and IntServ, is transparent toapplications. Nevertheless, applications stillneed to adapt tovarying QoS due to different availability of resources atvisited networks. BRENTA specifies four interfaces that offerdifferent levels of application involvement in the QoSadaptation. Secondly, we look at mobility support in the wirednetwork. We introduce the design of an all-IP Radio AccessNetwork (RAN) for the BRAIN scenario. This RAN specifies amicromobility protocol that installs per-host routes on accessnetwork routers. Thus, terminals maintain their IP addressduring handover and user data is routed in the RAN withoutadditional encapsulation. The main challenge in such RAN is theprovision of end-to-end QoS. BRAIN terminals use RSVP assignaling mechanism, therefore the RSVP path must be repairedafter handovers. We introduce the loose coupling of reservationand micromobility signaling to repair the RSVP path and showthat it can reduce the QoS degradation during handovers. A moregeneral survey of the interactions between QoS and mobilityprotocols is also presented.Finally, we present the design of an IP-based RAN for IEEE802.11 wireless LANs. It is a replacement to the currentEthernet?based one aimed at increasing the coverage areaof wireless LANs. Its architecture follows the generic RANarchitecture introduced in this thesis and includes most of thesuggested optimizations for RANs such as special support forbroadcasted frames and movement prediction plus n-casting toreduce handover time. Additionally, we also study the IEEE802.11 handover procedure and suggest several techniques toreduce it.
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