Daniel de Oliveira Cunha

The ad hoc return channel: a low-cost solution for Brazilian interactive digital TV

The upcoming terrestrial digital television technology brings a new class of services to traditional TV sets. A set-top box may, for example, access the Internet and send email. The interactive return channel makes these new services possible. This channel allows TV viewers to interact by sending data back to the TV broadcaster. In this article we analyze the viability of a wireless ad hoc network to implement the return channel. For this purpose, an ad hoc network is a low-cost and flexible solution. We evaluate the performance of an ad hoc return channel using the IEEE 802.11 wireless technology for different Brazilian geographical scenarios. The results show that ad hoc networking is a promising solution for the return channel of Brazilian interactive digital TV

Towards Stateless Single-Packet IP Traceback

The current Internet architecture allows malicious nodes to disguise their origin during denial-of-service attacks with IP spoofing. A well-known solution to identify these nodes is IP traceback. In this paper, we introduce and analyze a lightweight single-packet IP traceback system that does not store any data in the network core. The proposed system relies on a novel data structure called Generalized Bloom Filter, which is tamper resistant. In addition, an efficient improved path reconstruction procedure is introduced and evaluated. Analytical and simulation results are presented to show the effectiveness of the proposed scheme. The simulations are performed in an Internet-based scenario and the results show that the proposed system locates the real attack path with high accuracy.

Analyzing the Energy Consumption of IEEE 802.11 Ad Hoc Networks

This paper analyzes the energy consumption of ad hoc nodes using IEEE 802.11 interfaces. Our objective is to provide theoretical limits on the lifetime gains that can be achieved by different power saving techniques proposed in the literature. The evaluation takes into account the properties of the medium access protocol and the process of forwarding packets in ad hoc mode. The key point is to determine the node lifetime based on its average power consumption. The average power consumption is estimated considering how long the node remains sleeping, idle, receiving, or transmitting.

An Enhanced Routing Metric for Fading Wireless Channels

In this paper we propose the enhancement of routing metrics through a more complete view of the physical channel. Using cross-layer optimizations, we develop the distribution based expected transmission count (DBETX), which improves the performance of the network in the presence of varying channels. Through observations of the wireless link, nodes estimate how the wireless link behaves. The proposed metric exploits this estimation to increase routing efficiency. The proposed metric is shown to outperform the conventional ETX metric in the presence of fading. The improvement over ETX increases with the network density because connectivity increases and more routing options become available. Results show a reduction of up to 26% in the Average Number of Transmissions per link and an increase of up to 32% in the end-to-end availability.

HIP Tags Privacy Architecture

This paper describes an innovative and highly secure networking architecture, dedicated to the Internet of things (IoT). We propose an infrastructure that works with a new type of tags, supporting the recently standardized host identity protocol (HIP). Our main concern is to ensure RFID tags privacy, while enabling things to things communications.

Event-Driven Field Estimation for Wireless Sensor Networks

This paper introduces and analyzes a field estimation scheme for wireless sensor networks. Our scheme imitates the response of living beings to the surrounding events. The sensors define their periphery of attention based on their own readings. Readings differing from the expected behavior are considered events of interest and trigger the data transmission to the sink. The presented scheme is evaluated with real-site-collected data and the tradeoff between the amount of data sent to the sink and the reconstruction error is analyzed. Results show that significant reduction in the data transmission and, as a consequence, in the energy consumption of the network is achievable while keeping low the average reconstruction error.

A bio-inspired field estimation scheme for wireless sensor networks

This paper proposes and analyzes a bio-inspired field estimation scheme using wireless sensor networks. The proposed scheme exploits the temporal pattern of the sensed process to reduce the number of samples sent back to the sink by a sensor node and, as consequence, decrease the energy consumption in data transmission. The proposed scheme is orthogonal to the techniques that reduce the spatial density of collected samples deactivating nodes with similar measurements. Thus, the proposed scheme can be used along with these techniques. We present two variations of this scheme: a sample-bounded and an error-bounded. The sample-bounded limits the maximum number of samples sent back to the sink, while the error-bounded guarantees the observation of every event of interest. Results show that for very regular processes the scheme can reduce up to 90% the total amount of samples sent in the network and even for less regular processes the proposed scheme can reduce the total amount of samples sent from approximately 10 up to 20%, with small reconstruction errors.RésuméCet article propose et analyse un schéma d’estimation de champ bio-inspiré utilisant des réseaux de capteurs. Cette méthode exploite le motif temporel du processus capté pour réduire le nombre d’échantillons envoyés au récepteur par un noeud capteur et, par voie de conséquence, permet de réduire la consommation énergétique de la transmission. Ce schéma étant orthogonal aux techniques qui réduisent la densité spatiale des échantillons collectés en désactivant les noeuds donnant des mesures semblables, il peut être utilisé conjointement avec elles. Deux variantes sont proposées : la première limite le nombre maximal d’échantillons renvoyés au récepteur, la seconde garantit que tout événement intéressant sera observé. Les résultats indiquent que pour des processus très réguliers, il est possible de réduire de près de 90 % le nombre total d’échantillons envoyés dans le réseau et que lorsque les processus sont moins réguliers, la diminution peut tout de même atteindre 10 à 20% avec des erreurs de reconstruction faibles.

Wireless Ad Hoc Networks on Underserved Communities: An Efficient Solution for Interactive Digital TV

The Brazilian government intends to use the Digital TV technology as a vehicle of digital inclusion on underserved communities. The wireless ad hoc network is a low-cost, scalable and easy solution to implement the return channel. This work analyzes the performance of an ad hoc return channel using the wireless IEEE 802.11 technology in different Brazilian geographical scenarios. The results show that a high connectivity is achieved when more than 20% of the nodes are turned on, regardless of the position of the gateway. The influence of the number of hops and the number of transmitting nodes is also analyzed. A minimum throughput of 2 Mbps can be reached for increasing number of hops in the forwarding chain for a one-node transmission. Besides, when the number of transmitting nodes increases, the aggregated throughput can achieve 3.5 Mbps. The results show that the ad hoc network is a promising solution for the return channel of the interactive Digital TV.

An efficient admission control mechanism for optical burst-switched networks

This article proposes the load-level-based admission control (LLAC) mechanism in order to provide service differentiation for optical burst-switched networks. The LLAC mechanism admits bursts of a given service class according to the network load and a class-associated parameter. Based on this parameter, called load level, the proposed mechanism differentiates the burst blocking probability experienced by each service class. We develop an analytical model for the proposed mechanism and evaluate its performance for different configurations through mathematical analysis. The results show that the load-level-based mechanism reduces the blocking probability of high-priority bursts by two orders of magnitude or more depending on the analyzed scenario. In addition, compared to other similar mechanisms, the load-level-based mechanism effectively differentiates the services in all analyzed configurations, requires less states in optical burst switching (OBS) nodes, and does not suffer from priority inversion.

An efficient data transport protocol for Event-Driven Field-Estimation on sensor networks

This paper introduces and analyzes an event-driven field-estimation (EDFE) protocol for wireless sensor networks. In our field estimation scheme the sensors derive their own notion of expected reading. Readings differing from the expected are considered events of interest and trigger a data transmission to the sink. The proposed protocol allows sensor nodes to only transmit the events of interest, suppressing the transmission of less important data and, as a consequence, saving energy. The EDFE protocol allows the sink to synchronize the received data and correctly reconstruct the sampled process. The proposed scheme is evaluated in a realistic scenario using real-site collected data and representative network conditions. It is shown that the EDFE protocol reduces up to 50% the number of packets sent to the sink while keeping low the average reconstruction error. Moreover, it is demonstrated how the parameters can be tuned to increase the robustness of the protocol to network losses.