Michael Käsemann

Learn More
Existing position-based unicast routing algorithms which forward packets in the geographic direction of the destination require that the forwarding node knows the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages each node sends out periodically. Due to mobility, the information(More)
Communication between vehicles is likely to be one key area where mobile ad-hoc networks will be used in the near future. Currently there are several projects ([1, 3]) that investigate this application area, while car manufacturers and their suppliers aim at the development of products within the next few years. This raises the question what kind of routing(More)
We present and analyze a reactive location service (RLS) for mobile ad hoc networks. RLS provides a mobile node in a wireless ad-hoc network with the means to inquire the current geographical position of another node on-demand and can be used as a building block for location-based routing. We provide a comparison of RLS to an ideal omniscient location(More)
Existing position-based unicast routing algorithms, where packets are forwarded in the geographic direction of the destination, require that the forwarding node knows the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages each node sends out periodically. The transmission of(More)
Communication between vehicles is likely to be one key area where mobile ad-hoc networks will be used in the near future. Currently there are several projects ([1, 3]) that investigate this application area, while car manufacturers and their suppliers aim at the development of products within the next few years. This raises the question what kind of routing(More)
Position-based routing in a mobile ad hoc network requires geographic addresses. Thus, a node that wants to send a packet to some target node has to know the target’s (approximate) current position. In order to provide each node’s position to the other network nodes, a distributed location service has to be used. J. Li et al. recently put forward a(More)
In this paper we investigate the use of ad-hoc routing algorithms for the exchange of data between vehicles. There are two main aspects that are of interest in this context: the specific characteristics of ad-hoc networks formed by vehicles and the applicability of existing ad-hoc routing schemes to networks that display these characteristics. In order to(More)
In this paper we investigate the use of ad-hoc routing algorithms for the exchange of data between vehicles. There are two main aspects that are of interest in this context: the specific characteristics of ad-hoc networks formed by vehicles and the applicability of existing ad-hoc routing schemes to networks that display these characteristics. In order to(More)
This paper presents an MPEG-2 compatible adaptive quantization algorithm that leads to the optimal encoding of I-frames in the sense of maximizing PSNR. It integrates three key features into a single Lagrangian optimization model: adaptive quantization including quantizer-change overhead consideration, coefficient thresholding, and a new coefficient(More)
Position-based routing in a mobile ad hoc network requires geographic addresses. Thus, a node that wants to send a packet to some target node has to know the target’s (approximate) current position. In order to provide each node’s position to the other network nodes, a distributed location service has to be used. J. Li et al. recently put forward a(More)