Multiple hop routing in mobile ad hoc networks can minimize energy consumption and increase data throughput. Yet, the problem of radio interferences remains. However if the routes are restricted to a basic network based on local neighborhoods, these interferences can be reduced such that standard routing algorithms can be applied. We compare different network topologies for these basic networks with respect to degree, spanner-properties, radio interferences, energy, and congestion, i.e. the Yao-graph (aka. Θ-graph) and some also known related models, which will be called the SymmY-graph (aka. YS-graph), the SparsY-graph (aka.YY-graph) and the BoundY-graph. Further, we present a promising network topology called the HL-graph (based on Hierarchical Layers). Further, we compare the ability of these topologies to handle dynamic changes of the network when radio stations appear and disappear. For this we measure the number of involved radio stations and present distributed algorithms for repairing the network structure. MotivationOur research aims at the implementation of a mobile ad hoc network based on distributed robust communication protocols. Besides the traditional use of omni-directional transmitters, we want to investigate the effect of space multiplexing techniques and variable transmission powers on the efficiency and capacity of ad hoc networks. Therefore our radios can send and receive radio signals independently in k sectors of angle θ using one frequency. Furthermore, our radio stations can regulate its transmission power for each transmitted signal. To show that this approach is also suitable in practical situations, we are currently developing a communication module for the mini robot Khepera [11,8] that can transmit and receive in eight sectors using infrared light with variable transmission distances up to one meter, see Fig. 1. A colony of Khepera robots will be equipped with

No abstract

We investigate the problem of path selection in radio networks for a given set of sites in two-dimensional space. For some given static point-to-point communication demand we define measures for congestion, energy consumption and dilation that take interferences between communication links into account.We show that energy optimal path selection for radio networks can be computed in polynomial time. Then, we introduce the diversity g(V ) of a set V ⊆ Ê 2 . It can be used to upperbound the number of interfering edges. For real-world applications it can be regarded as Θ(log n). A main result of the paper is that a weak c-spanner construction as a communication network allows to approximate the congestionoptimal communication network by a factor of O(g(V ) 2 ).Furthermore, we show that there are vertex sets where only one of the performance parameters congestion, energy, and dilation can be optimized at a time. We show trade-offs lower bounding congestion × dilation and dilation × energy. For congestion and energy the situation is even worse. It is only possible to find a reasonable approximation for either congestion or energy minimization, while the other parameter is at least a polynomial factor worse than in the optimal network.

No abstract

No abstract