5,466 research outputs found
A Comprehensive Experimental Comparison of Event Driven and Multi-Threaded Sensor Node Operating Systems
The capabilities of a sensor network are strongly influenced by the operating system used on the sensor nodes. In general, two different sensor network operating system types are currently considered: event driven and multi-threaded. It is commonly assumed that event driven operating systems are more suited to sensor networks as they use less memory and processing resources. However, if factors other than resource usage are considered important, a multi-threaded system might be preferred. This paper compares the resource needs of multi-threaded and event driven sensor network operating systems. The resources considered are memory usage and power consumption. Additionally, the event handling capabilities of event driven and multi-threaded operating systems are analyzed and compared. The results presented in this paper show that for a number of application areas a thread-based sensor network operating system is feasible and preferable
DTLS Performance in Duty-Cycled Networks
The Datagram Transport Layer Security (DTLS) protocol is the IETF standard
for securing the Internet of Things. The Constrained Application Protocol,
ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for
securing application traffic. There has been much debate in both the
standardization and research communities on the applicability of DTLS to
constrained environments. The main concerns are the communication overhead and
latency of the DTLS handshake, and the memory footprint of a DTLS
implementation. This paper provides a thorough performance evaluation of DTLS
in different duty-cycled networks through real-world experimentation, emulation
and analysis. In particular, we measure the duration of the DTLS handshake when
using three duty cycling link-layer protocols: preamble-sampling, the IEEE
802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel
Hopping mode. The reported results demonstrate surprisingly poor performance of
DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange
more than 10 signaling packets, the DTLS handshake takes between a handful of
seconds and several tens of seconds, with similar results for different duty
cycling protocols. Moreover, because of their limited memory, typical
constrained nodes can only maintain 3-5 simultaneous DTLS sessions, which
highlights the need for using DTLS parsimoniously.Comment: International Symposium on Personal, Indoor and Mobile Radio
Communications (PIMRC - 2015), IEEE, IEEE, 2015,
http://pimrc2015.eee.hku.hk/index.htm
Self-Similarity in a multi-stage queueing ATM switch fabric
Recent studies of digital network traffic have shown that arrival processes in such an environment are more accurately modeled as a statistically self-similar process, rather than as a Poisson-based one. We present a simulation of a combination sharedoutput queueing ATM switch fabric, sourced by two models of self-similar input. The effect of self-similarity on the average queue length and cell loss probability for this multi-stage queue is examined for varying load, buffer size, and internal speedup. The results using two self-similar input models, Pareto-distributed interarrival times and a Poisson-Zeta ON-OFF model, are compared with each other and with results using Poisson interarrival times and an ON-OFF bursty traffic source with Ge ometrically distributed burst lengths. The results show that at a high utilization and at a high degree of self-similarity, switch performance improves slowly with increasing buffer size and speedup, as compared to the improvement using Poisson-based traffic
Proactive Highly Ambulatory Sensor Routing (PHASeR) protocol for mobile wireless sensor networks
This paper presents a novel multihop routing protocol for mobile wireless sensor networks called PHASeR (Proactive Highly Ambulatory Sensor Routing). The proposed protocol
uses a simple hop-count metric to enable the dynamic and robust routing of data towards the sink in mobile environments. It is motivated by the application of radiation mapping by unmanned vehicles, which requires the reliable and timely delivery of regular measurements to the sink. PHASeR maintains a gradient metric in mobile environments by using a global TDMA MAC layer. It also uses the technique of blind forwarding to pass messages through the network in a multipath manner. PHASeR is analysed mathematically based on packet delivery ratio, average packet delay, throughput and overhead. It is then simulated with varying mobility, scalability and traffic loads. The protocol gives good results over all measures, which suggests that it may also be suitable for a wider array of emerging applications
Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration in mmWave Cellular Networks
MmWave communications are expected to play a major role in the Fifth
generation of mobile networks. They offer a potential multi-gigabit throughput
and an ultra-low radio latency, but at the same time suffer from high isotropic
pathloss, and a coverage area much smaller than the one of LTE macrocells. In
order to address these issues, highly directional beamforming and a very
high-density deployment of mmWave base stations were proposed. This Thesis aims
to improve the reliability and performance of the 5G network by studying its
tight and seamless integration with the current LTE cellular network. In
particular, the LTE base stations can provide a coverage layer for 5G mobile
terminals, because they operate on microWave frequencies, which are less
sensitive to blockage and have a lower pathloss. This document is a copy of the
Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr.
Marco Mezzavilla and Prof. Michele Zorzi. It will propose an LTE-5G tight
integration architecture, based on mobile terminals' dual connectivity to LTE
and 5G radio access networks, and will evaluate which are the new network
procedures that will be needed to support it. Moreover, this new architecture
will be implemented in the ns-3 simulator, and a thorough simulation campaign
will be conducted in order to evaluate its performance, with respect to the
baseline of handover between LTE and 5G.Comment: Master's Thesis carried out by Mr. Michele Polese under the
supervision of Dr. Marco Mezzavilla and Prof. Michele Zorz
Application of advanced on-board processing concepts to future satellite communications systems: Bibliography
Abstracts are presented of a literature survey of reports concerning the application of signal processing concepts. Approximately 300 references are included
- …