Contributions to the usage of the internet over mobile networks
- Autores: Carles Gómez Montenegro
- Directores de la Tesis: Josep Paradells Aspas (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2007
- Idioma: español
- Tribunal Calificador de la Tesis: Sebastià Sallent Ribes (presid.), Jordi Casademont (secret.), Fernando José Casadevall Palacios (voc.), Luis Muñoz Gutiérrez (voc.), Pedro Ruiz Martinez (voc.)
- Materias:
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- Resumen
The Internet was born as a network where all elements were static and links were wired. The current spectrum of wireless technologies differs significantly from the networking paradigm assumed when the TCP/IP stack was built. This Ph.D. presents a study on performance of Internet communications over a set of current wireless technologies. The work mainly focuses on two kinds of scenarios: i) WWANs like GPRS and UMTS and ii) wireless multi-hop networks, including ad-hoc and sensor networks. First, the reasons for TCP/IP suboptimal peformance in the aforementioned scenarios are investigated and characterized. Second, in view of the identified problems, several optimization proposals are described and evaluated, including end-to-end techniques, routing protocol enhancements in wireless multi-hop networks and the usage of Performance Enhancing Proxies (PEPs).
An empirical evaluation has characterized the behavior of GPRS and UMTS as access technologies for Internet communications. GPRS constitutes a very limited pipe, with very low bit rates, long RTTs and mobility-related impairments. UMTS improves GPRS' figures and introduces soft handover support. However, both kinds of networks suffer high link underutilization due to long RTTs. (Furthermore, handover between both systems is not currently optimized.) Adequate IP and TCP settings can overcome in part WWANs limitations. At the application layer, a popular service like web browsing has been studied in a twofold way: i) empirically and ii) analytically, including now performance can be optimized by using adequate settings in either case. Wireless multi-hop networks may also be used for Internet access. The underlying focus of the research carried out regarding these scenarios has been on their ability to deliver data from one endpoint to another one. This Ph.D. has considered the contributions of physical layer, network layer and transport layer contributions to application-level connectivity. Several topological para
