Search results for "Wireless"
showing 10 items of 879 documents
Practical Considerations in the Implementation of Collaborative Beamforming on Wireless Sensor Networks
2017
Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These motes have their own power supply, processing unit, sensors and wireless communications However with many constraints, such as limited energy, bandwidth and computational capabilities. In these networks, at least one mote called a sink, acts as a gateway to connect with other networks. These sensor networks run monitoring applications and then the data gathered by these motes needs to be retrieved by the sink. When this sink is located in the far field, there have been many proposals in the literature based on Collaborative Beamforming (CB), also known as Distributed or Cooper…
Relay selection in FDD amplify-and-forward cooperative networks
2017
In this paper, the problems of relay selection and distributed beamforming are investigated for bi-directional dual-hop amplify-and-forward frequency-division duplex cooperative wireless networks. When using individual per-relay maximum transmission power constraint, it has been proven that the relay selection and beamforming optimization problem becomes NP hard and requires exhaustive search to find the optimal solution. Therefore, we propose a computationally affordable sub-optimal multiple relay selection and beamforming optimization scheme based on the l1 norm squared relaxation. The proposed scheme performs the selection for the two transmission directions, simultaneously, while aiming…
Enable concurrent transmissions with beamforming for broadband wireless access in CSMA/CA-based WLANs
2014
In CSMA/CA based wireless local networks, two stations are not allowed to transmit at the same time due to interference generated to each other, resulting in degraded throughput. Concurrent transmission, which enables simultaneous transmission of two or more stations under certain conditions, is able to overcome this problem, leading to enhanced channel utilization efficiency. Different from earlier work on this topic which focuses on omni-direction concurrent transmission, we introduce in this paper beamforming into a co-channel concurrent transmission scheme and investigate the benefits of concurrency with beamforming. The circumstances for concurrent transmission and frame scheduling are…
Stochastic Collaborative Beamforming in Wireless Sensor Networks
2018
Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These devices are constituted by a microcontroller, sensors, and they have the ability to communicate in the ISM frequency band using the IEEE 802.15.4 standard. They have their own power supply, AA or AAA batteries, processing unit, sensors and wireless communications. Usually, the motes exchange packets using a multihop routing, and the maximum communication distance emitter-receiver is around 100m. At least one mote acts as a gateway, and the data gathered by the sensors of each mote have to be sent to this mote that is named sink or Base Station (BS). In a WSN the BS is within t…
Towards Service-oriented 5G: Virtualizing the Networks for Everything-as-a-Service
2018
It is widely acknowledged that the forthcoming 5G architecture will be highly heterogeneous and deployed with a high degree of density. These changes over the current 4G bring many challenges on how to achieve an efficient operation from the network management perspective. In this article, we introduce a revolutionary vision of the future 5G wireless networks, in which the network is no longer limited by hardware or even software. Specifically, by the idea of virtualizing the wireless networks, which has recently gained increasing attention, we introduce the Everything-as-a-Service (XaaS) taxonomy to light the way towards designing the service-oriented wireless networks. The concepts, chall…
Design and validation of a wireless Body Sensor Network for integrated EEG and HD-sEMG acquisitions
2022
Sensorimotor integration is the process through which the human brain plans the motor program execution according to external sources. Within this context, corticomuscular and corticokinematic coherence analyses are common methods to investigate the mechanism underlying the central control of muscle activation. This requires the synchronous acquisition of several physiological signals, including EEG and sEMG. Nevertheless, physical constraints of the current, mostly wired, technologies limit their application in dynamic and naturalistic contexts. In fact, although many efforts were made in the development of biomedical instrumentation for EEG and High Density-surface EMG (HD-sEMG) signal ac…
Detecting faulty wireless sensor nodes through Stochastic classification
2011
In many distributed systems, the possibility to adapt the behavior of the involved resources in response to unforeseen failures is an important requirement in order to significantly reduce the costs of management. Autonomous detection of faulty entities, however, is often a challenging task, especially when no direct human intervention is possible, as is the case for many scenarios involving Wireless Sensor Networks (WSNs), which usually operate in inaccessible and hostile environments. This paper presents an unsupervised approach for identifying faulty sensor nodes within a WSN. The proposed algorithm uses a probabilistic approach based on Markov Random Fields, requiring exclusively an ana…
Examination of robust D-stability of TCP-DCR protocol
2012
This paper presents non-linear mathematical model of a computer network with a part of wireless network. The article contains an analysis of the stability of the network based on TCP-DCR, which is a modification of the traditional TCP. Block diagram of the network model was converted to a form in order to investigate the D-stability using the method of the space of uncertain parameters. Robust D-stability is calculated for constant delays values.
Underlay Device-to-Device Communications on Multiple Channels
2018
Author´s accepted manuscript (postprint). © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Since the spectral efficiency of wireless communications is already close to its fundamental bounds, a significant increase in spatial efficiency is required to meet future traffic demands. Device-to-device (D2D) communications provide such an increase by allowing nearby u…
<title>Statistical bandwidth allocation for multiservice networks</title>
2002
Multiservice networks will carry di erent kinds of applications in the near future. Bandwidth requirements change rapidly, and the network resource management will play an important role to guarantee the use of the limited resources in the most eAEcient way. We approach the channel capacity allocation problem by developing an SLA (Service Level Agreement) based channel allocation method. In our model, the channel may be wired or wireless, so this method can be adapted in multi-technique networks. The algorithm allocates resources to several di erent service classes via several di erent capacity routes. Service provider perfroms optimization by allocating data rate in such a way that the sat…