Increasing network lifetime by battery-aware master selection in radio networks

Mobile wireless communication systems often need to maximize their network lifetime (defined as the time until the first node runs out of energy). In the broadcast network lifetime problem, all nodes are sending broadcast traffic, and one asks for an assignment of transmit powers to nodes, and for sets of relay nodes so that the network lifetime is maximized. The selection of a relay set consisting of a single node (the ‘master’), can be regarded as a special case of this problem. We provide a mean value analysis of algorithms controlling the selection of a master node with the objective of maximizing the network lifetime. The results show that already for small networks simple algorithms can extend the average network lifetime considerably

Deterministic Digital Clustering of Wireless Ad Hoc Networks

We consider deterministic distributed communication in wireless ad hoc networks of identical weak devices under the SINR model without predefined infrastructure. Most algorithmic results in this model rely on various additional features or capabilities, e.g., randomization, access to geographic coordinates, power control, carrier sensing with various precision of measurements, and/or interference cancellation. We study a pure scenario, when no such properties are available. As a general tool, we develop a deterministic distributed clustering algorithm. Our solution relies on a new type of combinatorial structures (selectors), which might be of independent interest. Using the clustering, we develop a deterministic distributed local broadcast algorithm accomplishing this task in $O(\Delta \log^*N \log N)$ rounds, where $\Delta$ is the density of the network. To the best of our knowledge, this is the first solution in pure scenario which is only polylog$(n)$ away from the universal lower bound $\Omega(\Delta)$, valid also for scenarios with randomization and other features. Therefore, none of these features substantially helps in performing the local broadcast task. Using clustering, we also build a deterministic global broadcast algorithm that terminates within $O(D(\Delta + \log^* N) \log N)$ rounds, where $D$ is the diameter of the network. This result is complemented by a lower bound $\Omega(D \Delta^{1-1/\alpha})$, where $\alpha > 2$ is the path-loss parameter of the environment. This lower bound shows that randomization or knowledge of own location substantially help (by a factor polynomial in $\Delta$) in the global broadcast. Therefore, unlike in the case of local broadcast, some additional model features may help in global broadcast

Power aware broadcast trees for sensor networks

In a sensor network with nodes distributed randomly in a two dimensional plane, the problem of constructing a power aware broadcast tree from a given source node is a difficult problem when nodes have k different levels of power. In fact, it is known that the problem of constructing a broadcast tree that minimizes total power consumption is NP-hard; We investigate the development of a good approximation algorithm for generating power reduced broadcast trees for sensor networks. We are particularly interested in the diameter of the generated broadcast tree. Both theoretical investigation and simulated results are presented. We present two approximation algorithms (one based on a partitioning approach and the other based on a cluster following approach) for constructing broadcast tRees The experimental investigation shows that the proposed algorithms are very effective in generating power-reduced and hop-count-reduced broadcast tRee

Dynamic master selection in wireless networks

Abstract. Mobile wireless networks need to maximize their network lifetime (defined as the time until the first node runs out of energy). In the broadcast network lifetime problem, all nodes are sending broadcast traffic, and one asks for an assignment of transmit powers to nodes, and for sets of relay nodes so that the network lifetime is maximized. The selection of a dynamic relay set consisting of a single node (the ‘master’), can be regarded as a special case, providing lower bounds to the optimal lifetime in the general setting. This paper provides a first analysis of a ‘dynamic master selection’ algorithm

VCube-PS: A Causal Broadcast Topic-based Publish/Subscribe System

In this work we present VCube-PS, a topic-based Publish/Subscribe system built on the top of a virtual hypercube-like topology. Membership information and published messages are broadcast to subscribers (members) of a topic group over dynamically built spanning trees rooted at the publisher. For a given topic, the delivery of published messages respects the causal order. VCube-PS was implemented on the PeerSim simulator, and experiments are reported including a comparison with the traditional Publish/Subscribe approach that employs a single rooted static spanning-tree for message distribution. Results confirm the efficiency of VCube-PS in terms of scalability, latency, number and size of messages.Comment: Improved text and performance evaluation. Added proof for the algorithms (Section 3.4

Generating quality dominating set

Construction of a small size dominating set is a well known problem in graph theory and sensor networks. A Connected dominating set (CDS) can be used as a backbone structure in sensor networks for message delivery and broadcast. The general dominating set problem is known to be NP-hard and some approximation algorithms have been proposed; In most approximation algorithms for constructing connected dominating set only the size of the dominating set has been considered. In this thesis we address the problem of constructing connected dominating sets with several quality factors that include (i) diameter, (ii) risk-factor, and (iii) interference. We propose algorithms for constructing CDS of small diameter, reduced risk-factor, and reduced interference. We also report on the experimental investigation of the proposed techniques. Experimental results show that the proposed algorithms are very effective in reducing interference without significantly increasing CDS size. The proposed algorithms are the first algorithms in the sensor network community that address both size and interference for designing dominating sets