Location and routing optimization protocols supporting internet host mobility

PhD ThesisWith the popularity of portable computers and the proliferation of wireless networking interfaces, there is currently a great deal of interest in providing IP networking support for host mobility using the Internet as a foundation for wireless networking. Most proposed solutions depend on a default route through the mobile host's horne address, which makes for unnecessarily long routes. The major problem that this gives rise to is that of finding an efficient way of locating and routing that allows datagrams to be delivered efficiently to moving destinations whilst limiting costly Internet-wide location updates as much as possible. Two concepts - "local region" and "patron service" - are introduced based on the locality features of the host movement and packet traffic patterns. For each mobile host, the local region is a set of designated subnetworks within which a mobile host often moves, and the patrons are the hosts from which the majority of traffic for the mobile host originated. By making use of the hierarchical addressing and routing structure of Internet, the two concepts are used to confine the effects of a host moving, so location updates are sent only to a designated host moving area and to those hosts which are most likely to call again, thus providing nearly optimal routing for most communication. The proposed scheme was implemented as an IP extension using a network simulator and evaluated from a system performance point of view. The results show a significant reduction in the accumulated communication time along with improved datagram tunneling, as compared with its extra location overhead. In addition, a comparison with another scheme shows that our functionality is more effective both for location update and routing efficiency. The scheme offers improved network and host scalability by isolating local movement from the rest of the world, and provides a convenient point at which to perform administration functions

Transaction replication in mobile environments.

by Lau Wai Kwong.Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.Includes bibliographical references (leaves 99-102).Abstract --- p.iiAcknowledgements --- p.ivChapter 1 --- Introduction --- p.1Chapter 1.1 --- Limitations of the Mobile Computing Environments --- p.2Chapter 1.2 --- Applications of Transaction Replication in Mobile Environments --- p.5Chapter 1.3 --- Motivation for Transaction Replication in Mobile Environments --- p.5Chapter 1.4 --- Major Simulation Results --- p.6Chapter 1.5 --- Roadmap to the Thesis --- p.7Chapter 2 --- Previous and Related Research --- p.8Chapter 2.1 --- File Systems --- p.8Chapter 2.1.1 --- Management of Replicated Files --- p.8Chapter 2.1.2 --- Disconnected Operations --- p.10Chapter 2.2 --- Database Management --- p.12Chapter 2.2.1 --- Data Replication Schemes --- p.12Chapter 2.2.2 --- Cache Invalidation and Query Processing --- p.15Chapter 2.2.3 --- Transaction Management in Mobile Environments --- p.17Chapter 3 --- System Model and Assumptions --- p.21Chapter 3.1 --- System Architecture --- p.21Chapter 3.2 --- Transaction and Data Model --- p.23Chapter 3.3 --- One-copy Serializability --- p.25Chapter 3.4 --- Assumptions --- p.27Chapter 4 --- Transaction Replication in a Mobile Environment --- p.29Chapter 4.1 --- Read-only Public Transactions --- p.30Chapter 4.1.1 --- Data Broadcasting --- p.31Chapter 4.1.2 --- Cache Update --- p.33Chapter 4.1.3 --- Cache Miss --- p.36Chapter 4.1.4 --- Execution of Read-only Public Transactions --- p.37Chapter 4.2 --- R/W Public Transactions --- p.39Chapter 4.3 --- Correctness Argument --- p.41Chapter 4.3.1 --- Correctness Proof --- p.43Chapter 4.4 --- Extension to Support Partition Failures --- p.47Chapter 5 --- Design and Implementation of the Simulation --- p.49Chapter 5.1 --- CSIM Language --- p.49Chapter 5.2 --- Simulation Components --- p.50Chapter 5.2.1 --- Fixed Network --- p.50Chapter 5.2.2 --- Mobile Host --- p.50Chapter 5.2.3 --- Wireless Channel --- p.51Chapter 5.2.4 --- Database and Transactions --- p.52Chapter 5.3 --- A Lock-based Scheme --- p.53Chapter 5.4 --- Graphing ...........、 --- p.54Chapter 6 --- Results and Analysis --- p.55Chapter 6.1 --- Results Dissection --- p.55Chapter 6.2 --- Performance of the Scheme --- p.56Chapter 6.2.1 --- Parameters Setting --- p.56Chapter 6.2.2 --- Experiments and Results --- p.59Chapter 6.3 --- Comparison with the Lock-based Scheme --- p.78Chapter 6.3.1 --- Parameters Setting --- p.79Chapter 6.3.2 --- Experiments and Results --- p.80Chapter 7 --- Conclusions and Future Work --- p.93Chapter 7.1 --- Conclusions --- p.93Chapter 7.2 --- Future Work --- p.94Chapter A --- Implementation Details --- p.96Bibliography --- p.9

Support For IP mobility and diversity in a broadband wireless access network

Broadband wireless access (BWA) network working at millimetre bands possesses the advantages of quick deployment, more flexibility, wide service coverage and cost efficiency. The range of services to be provided via the system includes broadband digital television, Internet data, telephony and videoconference. Apart from broadcast digital television, all traffic is carried in Internetworking Protocol (IP) format. Unfortunately the services of such a system are susceptible to impairment by buildings, vegetation, terrain and attenuation caused by rain, snow and sleet, etc. Accordingly the service availability and system performance can drop dramatically. In the worst case, the system will experience heavy packet loss and the services might be completely unavailable. An extended multiprotocol label switching (MPLS) network architecture is proposed in this thesis, which allows fast mobile IP access and diversity routing for traffic under fade condition. This supports nomadic access, reduced packet loss and improved service availability in BWA network during system outage. Also developed herein is a Diversity and Shadow Flow Merging Mechanism, which, besides sending a packet on its normal path, also duplicates the packet and sends it on a separate, diverted labelled path. The shadow flow merging mechanism is responsible for merging the normal flow and shadow flow together and delivering the merged packet to its destination. It is anticipated that the packet can be successfully delivered to the destination even if one path fails completely during the system outage. The protocol is tested on a general BWA network that is configured with Digital Video Broadcast (DVB) downlink and Multi-Frequency Time Division Multiplex Access (MF-TDMA) uplink equipments. The protocol’s ability of reducing packet loss and improving service availability, during the period of link failure, is verified. It is concluded that the protocol is effective in improving the service availability of BWA network.EThOS - Electronic Theses Online ServiceGBUnited Kingdo