Search results for "ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS"
showing 10 items of 449 documents
Efficient Transport Protocol for Networked Haptics Applications
2008
The performance of haptic application is highly sensitive to communication delays and losses of data. It implies several constraints in developing networked haptic applications. This paper describes a new internet protocol called Efficient Transport Protocol (ETP), which aims at developing distributed interactive applications. TCP and UDP are transport protocols commonly used in any kind of networked communication, but they are not focused on real time application. This new protocol is focused on reducing roundtrip time (RTT) and inter packet gap (IPG). ETP is, therefore, optimized for interactive applications which are based on processes that are continuously exchanging data.ETP protocol i…
Performance Study of Non-beaconed and Beacon-Enabled Modes in IEEE 802.15.4 under Bluetooth Interference
2008
The IEEE 802.15.4 protocol is a flexible technology with great potential for wireless sensor networks applications. The standard distinguishes two network modes; beacon-enabled and nonbeacon-enabled. In this paper, the performance study of beaconed and non-beaconed modes of IEEE 802.15.4 is evaluated using on site PER measurements. The tests are carryout in an urban outdoor environment with commercial available equipment. Likewise, the impact of Bluetooth interference over IEEE 802.15.4 modes is evaluated. The results show that Bluetooth interference and the mode selected have effects over the PER. Furthermore, for distances between 3 to 10 meters the PER doesn't show significance distance …
EECDC-MAC: An energy efficient cooperative duty cycle MAC protocol
2012
In this paper, we propose a novel energy efficient cooperative duty cycle MAC (EECDC-MAC) protocol in which sensor nodes use fixed wakeup rendezvous scheduling to exchange messages and a cooperative transmission mechanism to avoid overuse of nodes with lower residual energy. Numerical results demonstrate that the EECDC-MAC protocol can prolong the entire network longevity efficiently in comparison with an existing cooperative duty cycle MAC protocol, CDC-MAC, and another popular duty cycle MAC protocol, prediction wakeup MAC (PW-MAC) protocol.
Formal verification of a Cooperative Automatic Repeat reQuest MAC protocol
2012
Author's version of an article published in the journal: Computer Standards & Interfaces. Also available from the publisher at: http://dx.doi.org/10.1016/j.csi.2011.12.001 Cooperative communications, in which a relay node helps the source node to deliver its packets to the destination node, are able to obtain significant benefits in terms of transmission reliability, coverage extension and energy efficiency. A Cooperative Automatic Repeat reQuest (C-ARQ) MAC protocol has been recently proposed to exploit cooperative diversity at the MAC layer. in this paper, we validate the integrity and the validity of the C-ARQ protocol using formal methods. The protocol logic is modeled in SDL and implem…
MAC Protocols for WuR Enabled WSNs : Design and Performance Evaluation
2017
Master's thesis Information- and communication technology IKT591 - University of Agder 2017 Increasing energy efficiency is a challenging task for protocol design in wireless sensor networks (WSNs) as well as in Internet of things (IoT). Traditionally, duty-cycled (DC) protocols have been widely adopted for data transmissions in WSNs for energy conservation by reducing idle listening and overhearing. Recently, wake-up radio (WuR) has merged as a promising technique to replace DC protocols thanks to its superior performance in both network lifetime and transmission latency. This thesis work focuses on the design and performance evaluation of WuR-enabled MAC protocols considering various traf…
Demo abstract: Cross-technology TDMA synchronization using energy pattern beacons
2017
When different technologies use the same frequency bands in close proximity, the resulting interference typically results in performance degradation. Coexistence methods exist, but these are often technology specific and require technology specific interference detection methods. To remove the root cause of the performance degradation, devices should be able to negotiate medium access even when using different technologies. To this end, an architecture that allows cross-technology medium access by means of a Time Division Multiple Access (TDMA) scheme was devised. In order to achieve cross-technology synchronization, which is required for the TDMA solution, an energy pattern beacon is trans…
On Applications of Wireless Sensor Networks
2009
Wireless Sensor Networks (WSN) are ad-hoc networks in which small independent sensor nodes have limited energy, computational resources and wireless communication capabilities. Recently, both academia and industry have shown great interest in the area of Wireless Sensor Networks. This paper focuses on the practical applications in commerce and feasible future employment of WSNs. Continued advances of wireless communication technologies have led to the following fields of applications: habitat and environmental monitoring, security of buildings and property, oil and gas installations, mines and tunnels, emergency medical care, military applications. In the near future WSNs will certainly ent…
Spectrum utilization over licensed and unlicensed bands
2016
Nowadays, telecommunication technology becomes one of the universal phenomenon used in people’s daily life. In recent years, the appearance of smartphones, tab lets, mobile Internet Apps and services led to mobile data traffic proliferating, and the devices and ser- vices will continue to increase dramatically for some time. The fact along with the tele- communication devices increasing to aggravate the overload problem is that the users seek for fast and reliable data transmission, as well as service continuity. To address the over- load issue, LTE-Unlicensed (LTE-U) turns out to be one of the reasonable solutions to provide high performance and seamless interoperability for users’ experie…
A Multi-Phase Decode-and-Forward Transmission Protocol in Cognitive Relay Networks: Outage Analysis and Relay Power Allocation
2015
Consider an underlay cognitive relay network with multiple source and destination pairs and that a decode-and-forward scheme is adopted at the relay. We propose a multi-phase transmission protocol in this paper which involves cooperation among source, relay and destination nodes. Given perfect interference elimination before decoding at the destination nodes, we derive closed-form expressions for outage probability calculation over Rayleigh fading channels. Furthermore, the optimal relay power allocation factor which leads to minimal outage probability is determined. Numerical results reveal the conditions under which satisfactory performance can be achieved based on the proposed scheme.
Is TCP Packet Reordering Always Harmful?
2004
IP networks do not provide any guarantee that packets belonging to the same flow are delivered in the correct order. Out-of-order reception of packets was commonly considered due to pathological network conditions (such as link failures, etc.). However, it has been shown that packet reordering is a phenomenon which occurs even in normal network operation, due to a number of link-level and/or router-level implementation features, such as local parallelism and load balancing. Packet reordering is intuitively considered as a negative phenomenon, which may severely affect TCP traffic performance since it is expected to cause inefficient usage of the available link bandwidth and is expected to i…