24 research outputs found
Augmented Tree-based Routing Protocol for Scalable Ad Hoc Networks
In ad hoc networks scalability is a critical requirement if these
technologies have to reach their full potential. Most of the proposed routing
protocols do not operate efficiently with networks of more than a few hundred
nodes. In this paper, we propose an augmented tree-based address space
structure and a hierarchical multi-path routing protocol, referred to as
Augmented Tree-based Routing (ATR), which utilizes such a structure in order to
solve the scalability problem and to gain good resilience against node
failure/mobility and link congestion/instability. Simulation results and
performance comparisons with existing protocols substantiate the effectiveness
of the ATR.Comment: Routing, mobile ad hoc network, MANET, dynamic addressing,
multi-path, distributed hash table, DH
On Reliability of Dynamic Addressing Routing Protocols in Mobile Ad Hoc Networks
In this paper, a reliability analysis is carried out to state a performance
comparison between two recently proposed proactive routing algorithms. These
protocols are able to scale in ad hoc and sensor networks by resorting to
dynamic addressing, to face with the topology variability, which is typical of
ad hoc, and sensor networks. Numerical simulations are also carried out to
corroborate the results of the analysis.Comment: Proc. of WRECOM '07: Wireless Rural and Emergency Communications
Conference, Roma (Italy), October 200
A Reliability-based Framework for Multi-path Routing Analysis in Mobile Ad-Hoc Networks
Unlike traditional routing procedures that, at the best, single out a unique
route, multi-path routing protocols discover proactively several alternative
routes. It has been recognized that multi-path routing can be more efficient
than traditional one mainly for mobile ad hoc networks, where route failure
events are frequent. Most studies in the area of multi-path routing focus on
heuristic methods, and the performances of these strategies are commonly
evaluated by numerical simulations. The need of a theoretical analysis
motivates such a paper, which proposes to resort to the terminal-pair routing
reliability as performance metric. This metric allows one to assess the
performance gain due to the availability of route diversity. By resorting to
graph theory, we propose an analytical framework to evaluate the tolerance of
multi-path route discovery processes against route failures for mobile ad hoc
networks. Moreover, we derive a useful bound to easily estimate the performance
improvements achieved by multi-path routing with respect to any traditional
routing protocol. Finally, numerical simulation results show the effectiveness
of this performance analysis.Comment: To appear on IJCNDS: International Journal of Communication Networks
and Distributed System
A Bayesian filtering technique for SAR interferometric phase fields
Abstract—SAR interferograms are affected by a strong noise component which often prevents correct phase unwrapping and always impairs the phase reconstruction accuracy. To obtain satisfactory performance, most filtering techniques exploit prior information by means of ad hoc, empirical strategies. In this paper, we recast phase filtering as a Bayesian estimation problem in which the image prior is modeled as a suitable Markov random field, and the filtered phase field is the configuration with maximum a posteriori probability. Assuming the image to be residue free and generally smooth, a two-component MRF model is adopted, where the first component penalizes residues, while the second one penalizes discontinuities. Constrained simulated annealing is then used to find the optimal solution. The experimental analysis shows that, by gradually adjusting the MRF parameters, the algorithm filters out most of the high-frequency noise and, in the limit, eliminates all residues, allowing for a trivial phase unwrapping. Given a limited processing time, the algorithm is still able to eliminate most residues, paving the way for the successful use of any subsequent phase unwrapping technique