539 research outputs found
Wireless body sensor networks for health-monitoring applications
This is an author-created, un-copyedited version of an article accepted for publication in
Physiological Measurement. The publisher is
not responsible for any errors or omissions in this version of the manuscript or any version
derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01
Efficient Resource Management Mechanism for 802.16 Wireless Networks Based on Weighted Fair Queuing
Wireless Networking continues on its path of being one of the most commonly used means of communication. The evolution of this technology has taken place through the design of various protocols. Some common wireless protocols are the WLAN, 802.16 or WiMAX, and the emerging 802.20, which specializes in high speed vehicular networks, taking the concept from 802.16 to higher levels of performance. As with any large network, congestion becomes an important issue. Congestion gains importance as more hosts join a wireless network. In most cases, congestion is caused by the lack of an efficient mechanism to deal with exponential increases in host devices. This can effectively lead to very huge bottlenecks in the network causing slow sluggish performance, which may eventually reduce the speed of the network. With continuous advancement being the trend in this technology, the proposal of an efficient scheme for wireless resource allocation is an important solution to the problem of congestion. The primary area of focus will be the emerging standard for wireless networks, the 802.16 or âWiMAXâ. This project, attempts to propose a mechanism for an effective resource management mechanism between subscriber stations and the corresponding base station
A Real-Time Implementation of the Mobile WiMAX ARQ and Physical Layer
This version of the article has been accepted for publication, after peer review and is
subject to Springer Natureâs AM terms of use, but is not the Version of Record and does
not reflect post-acceptance improvements, or any corrections. The Version of Record is
available online at: https://doi.org/10.1007/s11265-014-0890-3.[Abstract] This paper presents an innovative software-defined radio architecture for the real-time implementation of WiMAX transceivers. The architecture consists of commercially available field-programmable gate array and digital signal processor modules. We show how the architecture can be used for the real-time implementation of a full-featured standard-compliant time-division duplex WiMAX physical layer together with the ARQ functionality of the MAC layer. Both the mobile and the base station contain a transmitter and a receiver to enable real-time concurrent downlink and uplink communications. The design supports the different configurations defined by the standard and the WiMAX Forum. This work also provides the verification and validation of the proposed real-time implementation based on repeatable and reproducible performance evaluation considering the reference scenarios defined by the WiMAX Forum, including both static and mobile scenarios. Typical figures of merit such as physical-layer bit and frame error rates and MAC-layer throughput are obtained with the help of a custom-made real-time channel emulator implementing the channel models defined by the WiMAX Forum.This work has been partially supported by Indra
Sistemas S.A. and the Spanish Ministry of Defence with the technical
direction of PEC/ITM under grant DN8644-COINCIDENTE.
The authors wish to thank J. M. Camas-Albar from Indra Sistemas
S.A. for his help. This work has been additionally funded by Xunta
de Galicia, Ministerio de Ciencia e Innovacin of Spain, and FEDER
funds of the European Union under grants with numbers 2012/287,
TEC2010-19545-C04-01, and CSD2008-00010.Xunta de Galicia; 2012/28
Real-time validation of a SDR implementation of TDD WiMAX standard
[Abstract]: This paper focuses on the validation of an innovative software-
defined radio architecture for a WiMAX system based
on commercially available field-programmable gate array
and digital signal processor modules. We provide a realtime
implementation of a standard-compliant time-division
duplex physical layer including a mobile and a base station
as well as downlink and uplink communications, thus obtaining
a full-featured physical layer. Additionally, a set of
different configurations are supported as described in the
standard and in the WiMAX Forum. The main contribution
of the paper consists in a reproducible and repeatable validation
of the implementation in representative scenarios. At
the same time, a characterization of the performance exhibited
by the system is provided based on bit error rate measurements
carried out using a custom-made, real-time channel
emulator.This work has been partially supported by Indra Sistemas
S.A. and the Spanish Ministry of Defence with the technical
direction of PEC/ITM under grant DN8644-COINCIDENTE. The authors wish to thank J. M. Camas-
Albar from Indra Sistemas S.A. for his help.
This work has been additionally funded by Xunta de
Galicia, Ministerio de Ciencia e InnovaciĂłn of Spain, and
FEDER funds of the European Union under grants with
numbers 10TIC003CT, 09TIC008105PR, TEC2010-19545-
C04-01, and CSD2008-00010.Xunta de Galicia; 10TIC003CTXunta de Galicia; 09TIC008105P
A coarse-grained dynamically reconfigurable MAC processor for power-sensitive multi-standard devices
DRMP, a Dynamically Reconfigurable MAC Processor, is an innovative, dynamically reconfigurable System-on-Chip architecture. The architecture exploits substantial overlaps in the functionality of different wireless MAC layers. Its flexibility is specialized for addressing the requirements of the MAC layer of wireless standards. It is targeted at consumer, multi-standard, handheld devices, and its design is meant to address the balance of flexibility and power-efficiency that this target market demands. The DRMP reconfigures packet-by-packet on the fly, allowing execution of concurrent protocol modes on a single hardware co-processor. An interrupt-driven programming model has also been presented and shown to implement the protocol state-machine of the three protocols on a CPU. These features will allow the DRMP to replace three MAC processors in a hand-held device. The most innovative component of the DRMP architecture is its Interface and Reconfiguration Controller. It uses a combination of asynchronous controllers to dynamically reconfigure the functional units in the architecture and delegate MAC tasks to them. The architecture has been modeled in Simulink at cycle-approximate abstraction. Results of simulations involving transmission and reception of packets have been presented, showing that the platform concurrently handles three protocol streams, reconfigures dynamically, yet meets and exceeds the protocol timing constraints, all at a moderate frequency. Its heterogeneous and coarse-grained functional units, limited connectivity requirements between these units, and proportionally large time that these resources are idle, promise a very modest power-consumption, suitable for mobile devices, while offering flexibility to implement different MAC protocols
HopScotch - a low-power renewable energy base station network for rural broadband access
The provision of adequate broadband access to communities in sparsely populated rural areas has in the past been severely restricted. In this paper, we present a wireless broadband access test bed running in the Scottish Highlands and Islands which is based on a relay network of low-power base stations. Base stations are powered by a combination of renewable sources creating a low cost and scalable solution suitable for community ownership. The use of the 5~GHz bands allows the network to offer large data rates and the testing of ultra high frequency ``white space'' bands allow expansive coverage whilst reducing the number of base stations or required transmission power. We argue that the reliance on renewable power and the intelligent use of frequency bands makes this approach an economic green radio technology which can address the problem of rural broadband access
Evaluating WIMAX for real-time vehicular communications
Mestrado em Engenharia ElectrĂłnica e TelecomunicaçÔesOs acidentes rodoviĂĄrios tĂȘm um impacto elevado na sociedade, quer devido Ă s perdas humanas daĂ resultantes quer devido aos custos econĂłmicos associados. Este facto tem causado por todo o mundo o estudo de mecanismos que permitam aumentar a segurança rodoviĂĄria. Um exemplo disto Ă© o investimento da Europa em vĂĄrios projectos com vista a desenvolver estes mecanismos, onde a maior parte destas iniciativas consideram a possibilidade dos veĂculos comunicarem entre si e/ou com estaçÔes fixas, situadas junto da rodovia. A mobilidade dos veĂculos apresenta requisitos especiais, onde as comunicaçÔes sem-fios tĂȘm um papel crucial nestas aplicaçÔes.
Contudo, os serviços de segurança rodoviĂĄria requerem alguns requisitos especĂficos, como largura de banda ou em termos de timeliness, que tĂȘm de ser cumpridos independentemente da tecnologia sem-fios usada. Neste trabalho Ă© pretendido avaliar WiMAX para comunicaçÔes relacionadas com a segurança rodoviĂĄria, em que a coexistĂȘncia de diferentes tipos de serviços Ă© uma realidade, onde o uso dos mecanismos de qualidade de serviço fornecidos pelo WiMAX podem ser uma vantagem.
ABSTRACT: Road accidents have a huge impact on the society, both because of the
resulting human life losses and injuries as well as because of the associ-
ated economic costs. This situation fostered the study of mechanisms for
increasing road safety all over the world. In Europe, several projects are
being funded to develop such mechanisms. Many of the approaches that
are being pursued require the ability of the vehicles to communicate with
each other and/or with fixed roadside equipments. Due to the mobility con-
straints, wireless technologies have a crucial role in this kind of applications.
However, road safety services have also specific demands, in terms of band-
width and timeliness, that have to be met, independently of the wireless
technology used. In this work, it is performed an evaluation of WiMAX for
road safety communications, taking into consideration the coexistence of
different types of service and that the use of quality of service mechanisms
in this wireless technology could be an advantage
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