João H. Kleinschmidt

An Analytical Model for Energy Efficiency of Error Control Schemes in Sensor Networks

This paper analyzes the energy efficiency of wireless sensor networks using different error control schemes. An analytical model is presented to evaluate the energy efficiency in Nakagami-ra fading channels. The model is applied to error control schemes of Bluetooth technology. Some custom error control schemes and adaptive techniques using different FEC and ARQ strategies are analyzed. Performance results are obtained through analysis for networks with different number of hops and fading channel conditions.

An efficient polling strategy for Bluetooth piconets using channel state information

Bluetooth is an emerging technology for personal wireless communications and is being applied in many scenarios. We investigate the data scheduling policy for Bluetooth piconets. In general the performance evaluation of most piconet scheduling algorithms recently proposed do not consider the packet losses in the wireless channel. However in environments with high interference or mobility, the channel conditions can mitigate the performance of the polling strategies. We propose a new piconet scheduling algorithm based on the estimated channel state information. The channel is modeled using the Nakagami-m distribution. The channel quality estimation is based on the received signal-to-noise ratio (SNR) and on the Nakagami fading parameter m. These two metrics are used by the scheduling algorithm to define the best polling strategy. Simulation results demonstrate the good algorithm performance for different traffic conditions.

DNA sequences generated by ℤ 4 -linear codes

One of the puzzling problems in mathematical biology is to show the existence of any form of error-correcting code in the DNA structure. Here we propose a model for the biological coding system similar to that of a digital communication system. This model consists of an encoder (a mapper and a BCH code over ℤ4) and a modulator (genetic code). Here we show that DNA sequences including proteins and targeting sequences from different species with 63, 255, and 1023 nucleotides long were identified as codewords of ℤ4-linear codes.

Mitigating On-Off attacks in the internet of things using a distributed trust management scheme

In the Internet of Things (IoT), physical objects are able to provide or require determined services. The purpose of this work is to identify malicious behavior of nodes and prevent possible On-Off attacks to a multiservice IoT. The proposed trust management model uses direct information generated from direct communication with the nodes to evaluate trust between nodes. This distributed approach allows nodes to be completely autonomous in making decisions about the behavior of other nodes. We perform network simulations using Contiki-OS to analyze the performance of the proposed trust model. Simulation results show effectiveness against On-Off attacks and also a good performance to recognize malicious nodes in the network.

Is a Genome a Codeword of an Error-Correcting Code?

Since a genome is a discrete sequence, the elements of which belong to a set of four letters, the question as to whether or not there is an error-correcting code underlying DNA sequences is unavoidable. The most common approach to answering this question is to propose a methodology to verify the existence of such a code. However, none of the methodologies proposed so far, although quite clever, has achieved that goal. In a recent work, we showed that DNA sequences can be identified as codewords in a class of cyclic error-correcting codes known as Hamming codes. In this paper, we show that a complete intron-exon gene, and even a plasmid genome, can be identified as a Hamming code codeword as well. Although this does not constitute a definitive proof that there is an error-correcting code underlying DNA sequences, it is the first evidence in this direction.

Adaptive error control using ARQ and BCH codes in sensor networks using coverage area information

This paper proposes adaptive error control strategies for wireless sensor networks using informational value of messages. The informational value is based on sensors coverage area. Important packets are protected by more powerful error control schemes than less important packets. BCH codes and retransmission schemes were analyzed using OQPSK modulation in Rayleigh fading channels. The results obtained show that the adaptive schemes improve the reliability of packets with high informational value without a significant increase in the energy consumption.

Capture and Analysis of Malicious Traffic in VoIP Environments Using a Low Interaction Honeypot

The number of users of VoIP services is increasing every year. Consequently, VoIP systems get more attractive for attackers. This paper describes the implementation of a low interaction honeypot for monitoring illegal activities in VoIP environments. The honeypot operated during 92 days and collected 3502 events related to the SIP protocol. The analysis of the results allows understanding the modus operandi of the attacks targeted to VoIP infrastructures. These results may be used to improve defense mechanisms such as firewalls and intrusion detection systems.

Power efficient error control for Bluetooth-based sensor networks

This paper studies different error control schemes in wireless sensor networks with Bluetooth technology. The tradeoff between reliability and energy consumption of Bluetooth packets are analyzed, using different error control techniques, such as retransmission and channel coding. The AUX1 packet is utilized for custom coding and also adaptive techniques are proposed based on the number of hops of the network. The wireless channel is modeled with Rayleigh fading. The results obtained may be used as references to determine the packet type in a sensor application

Bluetooth Network Performance in Nakagami-m Fading Channels

The Bluetooth standard is considered a promising technology for implementing ad-hoc networks. This paper addresses issues related to Bluetooth performance in Nakagami-m fading channels. This distribution allows a better channel characterization for mobile and wireless communications. The throughput of Bluetooth links using asynchronous packets is investigated. Useful relations between packet error rate and node distances are derived. These results can be used as benchmarks for performance analysis or incorporated into Bluetooth network simulation tools. As an example, we evaluate by computer simulation the performance of a scatternet in a Nakagami fading scenario.

Analyzing and improving the energy efficiency of IEEE 802.15.4 wireless sensor networks using retransmissions and custom coding

This paper analyzes the performance of error control strategies in IEEE 802.15.4 wireless sensor networks. ARQ schemes of the IEEE 802.15.4 are used and also we propose custom coding using BCH codes. The performance is analyzed through simulation using the energy efficiency parameter. Performance results are obtained for multi-hop networks with different channel conditions and packet sizes. The results have shown that the ARQ scheme and BCH codes are energy efficient for networks with high number of hops and low values of signal-to-noise ratio.