Search results for "Communications"

Towards Risk-aware Access Control Framework for Healthcare Information Sharing

2018

Improving the multiple errors detection coverage in distributed embedded systems

2004

Currently, a lot of critical applications in automobile and aircraft avionics are built on fault-tolerant real-time distributed embedded systems. Fault injection techniques have been used extensively in the experimental validation of these systems and it is a challenge to adapt them to the demands of new technologies. This paper deals with the effect of physical faults at pin level on the Communication Network Interface in a prototype based on time-triggered architecture. Due to the essential necessity of observing system behavior during injection experiments, a suitable monitor for distributed embedded systems is proposed. The monitor is used to detect failures in the value domain that cou…

Performance analysis of binary DPSK modulation schemes over Hoyt fading channels

2009

This paper presents a performance analysis of differential phase shift keying (DPSK) modulation schemes over Hoyt fading channels. Based upon the theory of DPSK modulation and a recently derived formula for the probability density function (PDF) of the differential phase between two Hoyt vectors contaminated by additive white Gaussian noise (AWGN), the bit error probability (BEP) for DPSK systems with noncoherent demodulation over Hoyt channels is analyzed. In the analysis, the correlation between adjacent bits is taken into account. The obtained theoretical results are fully validated first by reducing them to the corresponding known solutions for the Rayleigh fading distribution being a s…

Priority Enabled Grant-Free Access With Dynamic Slot Allocation for Heterogeneous mMTC Traffic in 5G NR Networks

2021

Although grant-based mechanisms have been a predominant approach for wireless access for years, the additional latency required for initial handshake message exchange and the extra control overhead for packet transmissions have stimulated the emergence of grant-free (GF) transmission. GF access provides a promising mechanism for carrying low and moderate traffic with small data and fits especially well for massive machine type communications (mMTC) applications. Despite a surge of interest in GF access, how to handle heterogeneous mMTC traffic based on GF mechanisms has not been investigated in depth. In this paper, we propose a priority enabled GF access scheme which performs dynamic slot …

DTMC modeling for performance evaluation of DW-MAC in wireless sensor networks

2016

Synchronized duty cycling (DC) aligns sensor nodes to wake up at the same time in order to reduce idle listening for medium access control (MAC) in wireless sensor networks (WSNs). Demand wakeup MAC (DW-MAC) is a popular synchronous DC MAC protocol which allows nodes to compete and transmit multiple packets in one operational cycle. This multiple packet transmission (MPT) feature makes DW-MAC more energy efficient when comparing with other existing single time competition based protocols such as sensor MAC (S-MAC). In the literature, no analytical model exists to evaluate the performance of DW-MAC. In this paper, we develop two associated discrete time Markov chain (DTMC) models and incorpo…

Bluetooth throughput measures for cardiomyocyte extracellular signal telemetry

2006

In this contribution the suitability of the Bluetooth transmission system is analyzed for its application to the realtime transmission of cardiac signals captured by micro-electrode array sensors. The required data rates for this type of cardiac signals are calculated to be 180 kbps for every single micro- electrode. The mean throughput value varies with the selected packet size: for packet sizes less than 1000 bytes the mean throughput is smaller than 180 kbps while for packet sizes greater than 1000 bytes the mean throughput saturates at around 230 kbps. This mean throughput value is guaranteed for over 80% of the time. Compression algorithms running on the sensor array allow the reductio…

Probabilistic Transition-Based Approach for Detecting Application-Layer DDoS Attacks in Encrypted Software-Defined Networks

2017

With the emergence of cloud computing, many attacks, including Distributed Denial-of-Service (DDoS) attacks, have changed their direction towards cloud environment. In particular, DDoS attacks have changed in scale, methods, and targets and become more complex by using advantages provided by cloud computing. Modern cloud computing environments can benefit from moving towards Software-Defined Networking (SDN) technology, which allows network engineers and administrators to respond quickly to the changing business requirements. In this paper, we propose an approach for detecting application-layer DDoS attacks in cloud environment with SDN. The algorithm is applied to statistics extracted from…

Service level guarantee framework for IoT environments

2017

Nowadays, providing IoT environments with service level guarantee is a challenging task. We propose a framework for IoT service level guarantee thanks to several specific Service Level Agreements (SLAs) for IoT environments. We specify different SLAs for each entity contributing in our IoT architecture in order to conclude a global SLA called IoT-SLA (iSLA). These different SLAs enable IoT service provision with Quality of Service (QoS) guarantee. Achieving this guarantee requires several communications and interactions between the components of the proposed IoT architecture. These interactions allow an IoT Service Provider (IoT-SP) to conclude the iSLA with an IoT Client (IoT-C). We specif…

Channel Occupancy-Based Dynamic Spectrum Leasing in Multichannel CRNs: Strategies and Performance Evaluation

2016

Spectrum leasing has been proposed as an effective approach for enabling more flexible spectrum utilization in CRNs. In CRNs, a primary network (PN) which consists of multiple primary users (PUs) can lease part of the licensed spectrum to secondary users (SUs) in exchange for operational benefits. The focus of this study is to investigate how and to what extent the PN allows spectrum leasing in CRNs, considering the QoS requirements of the PN and the secondary network (SN). Correspondingly, we propose two dynamic spectrum leasing strategies, which can improve the QoS performance of SUs while ensuring sufficient remuneration for PUs. In order to dynamically adjust the portion of leased bandw…

A new inter-cloud service-level guarantee protocol applied to space missions

2017

Nowadays, the term cloud computing often falsely assumes the availability of an unlimited pool of resources. On the contrary, if a cloud provider reaches its limits, it may pose the risk of breaking their service level agreement (SLA). Space agencies could start using the cloud computing model within their IT infrastructure with multiple ground control points around the world to reduce the cost. An inter-cloud communication protocol with a guarantee of the service level will significantly reduce the cost if each ground control segment is considered as a cloud provider. This paper outlines a new protocol that was developed to take into consideration the end-to-end service-level guarantee. Th…