Biblio
We consider wireless networks in which the effects of interference are determined by the SINR model. We address the question of structuring distributed communication when stations have very limited individual capabilities. In particular, nodes do not know their geographic coordinates, neighborhoods or even the size n of the network, nor can they sense collisions. Each node is equipped only with its unique name from a range \1, ..., N\. We study the following three settings and distributed algorithms for communication problems in each of them. In the uncoordinated-start case, when one node starts an execution and other nodes are awoken by receiving messages from already awoken nodes, we present a randomized broadcast algorithm which wakes up all the nodes in O(n log2 N) rounds with high probability. In the synchronized-start case, when all the nodes simultaneously start an execution, we give a randomized algorithm that computes a backbone of the network in O(Δ log7 N) rounds with high probability. Finally, in the partly-coordinated-start case, when a number of nodes start an execution together and other nodes are awoken by receiving messages from the already awoken nodes, we develop an algorithm that creates a backbone network in time O(n log2 N + Δ log7 N) with high probability.
For authenticating time critical broadcast messages, IEEE 1609.2 security standard for Vehicular Ad hoc Networks (VANETs) suggests the use of secure Elliptic Curve Digital Signature Algorithm (ECDSA). Since ECDSA has an expensive verification in terms of time, most commonly suggested alternate algorithms are TESLA and signature amortization. Unfortunately, these algorithms lack immediate authentication and non-repudiation. Therefore, we introduce a probabilistic verification scheme for an ECDSA-based authentication protocol. Using ns2 simulation tools, we compare the performance of all above-mentioned broadcast authentication algorithms. The results show with our proposed scheme, there is an increase in packet processed ratio over that of all the other algorithms.
Selective encryption designates a technique that aims at scrambling a message content while preserving its syntax. Such an approach allows encryption to be transparent towards middle-box and/or end user devices, and to easily fit within existing pipelines. In this paper, we propose to apply this property to a real-time diffusion scenario - or broadcast - over a RTP session. The main challenge of such problematic is the preservation of the synchronization between encryption and decryption. Our solution is based on the Advanced Encryption Standard in counter mode which has been modified to fit our auto-synchronization requirement. Setting up the proposed synchronization scheme does not induce any latency, and requires no additional bandwidth in the RTP session (no additional information is sent). Moreover, its parallel structure allows to start decryption on any given frame of the video while leaving a lot of room for further optimization purposes.
This paper addresses the minimum transmission broadcast (MTB) problem for the many-to-all scenario in wireless multihop networks and presents a network-coding broadcast protocol with priority-based deadlock prevention. Our main contributions are as follows: First, we relate the many-to-all-with-network-coding MTB problem to a maximum out-degree problem. The solution of the latter can serve as a lower bound for the number of transmissions. Second, we propose a distributed network-coding broadcast protocol, which constructs efficient broadcast trees and dictates nodes to transmit packets in a network coding manner. Besides, we present the priority-based deadlock prevention mechanism to avoid deadlocks. Simulation results confirm that compared with existing protocols in the literature and the performance bound we present, our proposed network-coding broadcast protocol performs very well in terms of the number of transmissions.