Univ., Diss.--Karlsruhe, 2006. / Auch im Internet unter der Adresse http://www.uvka.de/univerlag/volltexte/2007/219/pdf/Kraft_Daniel.pdf verfügbar. Hergestellt on demand.

Abstract With the prosperity of the internet network, there are more and more wireless mobile devices producing, so people are greater and greater to the demand for internet access at any time. Some studies that integrate the Ad Hoc network into the internet in order to achieve the aim of the internet access on the go. Among them someone proposes that there is a part of Ad Hoc network MNs that can connect with BS, these MNs can be selected to act as Internet Gateway(IG), other MNs which can not connect with BS will convey the date to the internet through the IG. But IG itself is a MN, so IG switching is the most important factor to influence the performance of network, because at this switching time, Ad Hoc network does not connect with internet, all MNs must suspend transmission. If this swtiching time is too long, that will cause the efficiency of the network to glide seriously. Therefore, we propose some improvement methods and combine L2 trigger to reduce the delay time, and we utilize AR and BG selection to determine new DG produced to reduce DG switching times. Keyword: ad hoc¡AGateway

This paper proposed BRQ (Bandwidth-Reservation QoS scheme) for mobile Ad-Hoc wireless network. Unlike many schemes about IFS or backoff time interval of DCF in IEEE 802.11, BRQ uses the bandwidth reservation mechanism to support QoS. Because of the compatibility of BRQ with other schemes, we believe that BRQ scheme can achieve higher performance by integrating with other schemes. We evaluate the performance of BRQ, DCF in IEEE 802.11, EDCF in 802.11e, and BRQ+ (the combined scheme of BRQ and EDCF) in terms of their differentiation capability, network throughput, and average end-to-end delay. The simulation results demonstrate the effectiveness of the BRQ scheme and show that the BRQ+ scheme can achieve higher performance by integrating BRQ and EDCF.

The Dynamic Source Routing (DSR) protocol usually utilizes route caching to reduce the routing overhead and route discovery latency. For caches to be effective, the protocol needs to adapt to the frequent topology changes. In this paper, we propose two mechanisms to improve cache correctness and route stability. The first is the RERR-Enhance mechanism in which a broken link message will be sent to all nodes that had cached the broken link. The second mechanism is the hierarchical link cache structure accompanied with a link stability measurement. The cache in each node falls into two tiers: the primary cache and the secondary cache. The node selects a route from the primary cache first, based on link stability, to provide stable transmission. The proposed mechanism reduces at least 13% of the broken link messages; it also reduces routing overhead and end-to-end delay, compared to DSR with path caches and with Link-MaxLife, an adaptive timeout mechanism for link caches.

Lately, the security in wireless network is always a really hot topic. With the popularity of wireless network in our daily life day after day, the issues of connection speed have evolved to emphasize on personal privacy and information security. Due to the complication of membership in wireless network, it is hard to identify every member. We can reference to the security mechanism in wired network, and try to modify it to fit in wireless network. Of course, the wireless devices do not have such strong processing power and resources as personal computers or servers. So when we try to modify the security mechanism in wired network, we should think about the difference between wired and wireless devices. In this paper, we use a special method to establish Ad Hoc network architecture, and SSL ( Security Sockets Layer ) security protocol. Because SSL has been widely implemented and is now the main standard for providing security e-commerce transactions over the Web. Besides, we use ECC ( Elliptic Curve Cryptosystems ) to replace traditional RSA. Though RSA is the most widely used public key cryptosystem today, the implementation of RSA requires expensive computation. Since battery/computing power and bandwidth are scarce in mobile and wireless systems, the use of a computationally intensive cryptosystem, such as RSA, is not a feasible choice in such environments. Then we can establish a security environment in Ad Hoc network. We hope we can take a excellent balance between security and processing complexity. This paper goes toward the direction, and tries to move SSL to wireless networks. We believe that it is a method to give consideration to practical utility and ideal.

Reproduction de : Thèse de doctorat : Informatique et télécommunications : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 79 réf.

Thèse de doctorat : Mathématiques et informatique. Informatique : Bordeaux 1 : 2009. / Titre provenant de l'écran-titre.

Zugl.: Karlsruhe, Univ., Diss., 2006

Zugl.: Köln, Univ., Diss., 2006

Stuttgart, Univ., Diplomarb., 2004.