90 research outputs found
Delay versus energy consumption of the IEEE 802.16e sleep-mode mechanism
We propose a discrete-time queueing model for the
evaluation of the IEEE 802.16e sleep-mode mechanism of Power Saving Class (PSC) I in wireless access networks. Contrary to previous studies, we model the downlink traffic by means of a Discrete Batch Markov Arrival Process (D-BMAP) with N phases, which allows to take traffic correlation into account. The tradeoff between energy saving and increased packet delay is discussed. In many situations, the sleep-mode performance improves for heavily correlated traffic. Also, when compared to other strategies, the exponential sleep-period update strategy of PSC I may not always be the best
On analyzing the intra-frame power saving potentials of the IEEE 802.16e downlink vertical mapping
Worldwide Interoperability for Microwave Access (WiMAX) is generally considered as a competitive candidate networking technology for the realization of the 4G vision. Among the key factors towards its successful and widespread deployment are the effective support of mobility and the provision of mechanisms for enabling service access at a high quality level in an efficient and cost-effective manner. Nonetheless, this effort should take into account and adequately address strict and severe energy limitations that the mobile devices are currently facing. Power saving constitutes an issue of vital importance, as mobile terminals continue to incorporate more and more functionalities and energy-hungry features in order to support the ever increasing user requirements and demands. The standard employs variations of power saving classes in a frame-to-frame basis, while recent power saving mechanisms proposed in related research literature limit their activity in whole frames, neglecting, thus, the intra-frame power saving capabilities. In this work, the intra-frame energy conservation potentials of the mobile WiMAX network are studied and a novel analytical approach is provided, focusing on the downlink direction where the bandwidth allocation involves idle intervals and dynamic inactivity periods. Specifically, we endeavour to accurately analyse the potential energy conservation capabilities in an intra-frame point of view, applying the well-known simple packing algorithm to distribute the available bandwidth to the various subscribers. Our analytical findings are thoroughly cross-validated via simulation, providing clear insights into the intra-frame energy reduction capabilities
Energy efficiency in next generation wireless networks: methodologies, solutions and algorithms
Mobile Broadband Wireless Access (BWA) networks will offer in the forthcoming years multiple and differentiated services to users with high mobility requirements, connecting via portable or wearable devices which rely on the use of batteries by necessity. Since such devices consume a relatively large fraction of energy for transmitting/receiving data over-the-air, mechanisms are needed to reduce power consumption, in order to increase the lifetime of devices and hence improve userâs satisfaction. Next generation wireless network standards define power saving functions at the Medium Access Control (MAC) layer, which allow user terminals to switch off the radio transceiver during open traffic sessions for greatest energy consumption reduction. However, enabling power saving usually increases the transmission latency, which can negatively affect the Quality of Service (QoS) experienced by users. On the other hand, imposing
stringent QoS requirements may limit the amount of energy that can be saved.
The IEEE 802.16e standard defines the sleep mode is power saving mechanism with the purpose of reducing energy consumption. Three different operation classes are provided, each one to serve different class of traffic: class I, best effort traffic, class II real time traffic and class III multicast traffic. Several aspects of the sleep mode are left unspecified, as it is usually done in standards, allowing manufacturers to implement their own proprietary solutions, thus gaining a competitive advantage over the rivals.
The work of this thesis is aimed at verifying, the effectiveness of the power saving mechanism proposed into IEEE 802.16e standard, focusing on the mutual interaction between power saving and QoS support. Two types of delay constrained applications with different requirements are considered, i.e., Web and Voice over IP (VoIP). The performance is assessed via detailed packet-level simulation, with respect to several system parameters. To capture the relative contribution of all the factors on the energy- and QoS-related metrics, part of the evaluation is carried out by means of 2k · r! analysis. Our study shows that the sleep mode can achieve significant power consumption reduction, however,
when real time traffic is considered a wise configuration of the parameters is mandatory in order to avoid unacceptable degradation of the QoS.
Finally, based on the guidelines drawn through the analysis, we extend our contribution beyond a simple evaluation, proposing a power saving aware
scheduling framework aimed at reducing further the energy consumption. Our framework integrates with existing scheduling policies that can pursue their original goals, e.g. maximizing throughput or fairness, while improving the energy efficiency of the user terminals. Its effectiveness is assessed through an extensive packet level simulation campaign
Quality of service in WiMAX networks
Mestrado em Engenharia Electrónica e TelecomunicaçÔesO acesso à banda larga é um requisito importante na actualidade para satisfazer os utilizadores em termos de novas aplicaçÔes e serviços em tempo
real. O WiMAX, como tecnologia sem fios para ĂĄreas metropolitanas, prometendo cobrir uma maior superfĂcie e com maior dĂ©bito, Ă© uma tecnologia
promissora para as redes de prĂłxima geração. No entanto um requisito importante para a instalação e massificação desta tecnologia Ă© o seu comportamento a nĂvel de qualidade de serviços e garantia aos utilizadores do cumprimento eficiente dos requisitos de QoS.
Esta tese aborda e estuda o suporte de qualidade de serviços para redes WiMAX presente em diferentes modelos de simulação, implementados na ferramenta de simulação ns-2. Para além da validação e comparação entre os modelos existentes, também é efectuada a especificação e implementação de uma solução de QoS composta por um classificador e escalonador, e é
proposto e avaliado um algoritmo de escalonamento que utiliza prioritização de
classes de serviço e informação fĂsica dinĂąmica âcross layerâ para decisĂ”es de escalonamento no simulador.
Para validar e avaliar as soluçÔes propostas e desenvolvidas, um conjunto de cenĂĄrios orientados para a utilização de vĂĄrios serviços e aferição de mĂ©tricas de QoS foram simulados. Os resultados obtidos mostram a diferenciação entre distintas classes de trĂĄfego. O mecanismo proposto apresenta um pequeno ganho em dĂ©bito e latĂȘncia comparativamente Ă s soluçÔes previamente
analisadas/implementadas.
ABSTRACT: Broadband access is an important requirement to satisfy user demands and support a new set of real time services and applications. WiMAX, as a
Broadband Wireless Access solution for Wireless Metropolitan Area Networks, covering large distances with high throughputs, is a promising technology for Next Generation Networks. Nevertheless, for the successful deployment and
massification of WiMAX based solutions, Quality of Service (QoS) is a mandatory feature that must be supported.
In this thesis , the QoS support for WiMAX in ns-2 simulation software is addressed. A QoS framework, composed by a packet classification mechanism
and a scheduler, has been specified and implemented on the simulator, providing service differentiation over WiMAX networks. Furthermore, validation and comparison of different IEEE 802.16 simulation models is provided. Finally a scheduling solution is proposed and evaluated that uses prioritization and dynamic cross layer information for schedulling decisions in WiMAX networks.
In order to validate the developed solutions, a set of QoS oriented scenarios have been simulated and the obtained results show that the implemented
schedullers are able to efficiently differentiate between the different traffic classes and achieve gains in throughput and delay
4G Technology Features and Evolution towards IMT-Advanced
Kiinteiden- ja mobiilipalveluiden kysyntĂ€ kasvaa nopeasti ympĂ€ri maailmaa. ĂlykkĂ€iden pÀÀtelaitteiden, kuten iPhone:n ja Nokia N900:n markkinoilletulo yhdistettynĂ€ nĂ€iden korkeaan markkinapenetraatioon ja korkealuokkaiseen kĂ€yttĂ€jĂ€kokemukseen lisÀÀvĂ€t entisestÀÀn palveluiden kysyntÀÀ ja luovat tarpeen jatkuvalle innovoinnille langattomien teknologioiden alalla tavoitteena lisĂ€kapasiteetin ja paremman palvelunlaadun tarjoaminen.
Termi 4G (4th Generation) viittaa tuleviin neljÀnnen sukupolven mobiileihin langattomiin palveluihin, jotka International Telecommunications Union:in Radiocommunication Sector (ITU-R) on mÀÀritellyt ja nimennyt International Mobile Telecommunications-Advanced (IMT-Advanced). NÀmÀ ovat jÀrjestelmiÀ, jotka pitÀvÀt sisÀllÀÀn IMT:n ne uudet ominaisuudet, jotka ylittÀvÀt IMT-2000:n vaatimukset. Long Term Evolution-Advanced (LTE-Advanced) ja IEEE 802.16m ovat IMT-A sertifiointiin lÀhetetyt kaksi pÀÀasiallista kandidaattiteknologiaa.
TÀssÀ diplomityössÀ esitellÀÀn kolmannen sukupolven jÀrjestelmien kehityspolku LTE:hen ja IEEE 802.16e-2005 asti. LisÀksi työssÀ esitetÀÀn LTE-Advanced:n ja IEEE 802.16m:n uudet vaatimukset ja ominaisuudet sekÀ vertaillaan nÀiden lÀhestymistapoja IMT-A vaatimusten tÀyttÀmiseksi. Lopuksi työssÀ luodaan katsaus LTE ja IEEE 802.16e-2005 (markkinointinimeltÀÀn Mobile WiMAX) -jÀrjestelmien markkinatilanteeseen.The demand for affordable bandwidth in fixed and mobile services is growing rapidly around the world. The emergence of smart devices like the iPhone and Nokia N900, coupled with their high market penetration and superior user experience is behind this increased demand, inevitably driving the need for continued innovations in the wireless data technologies industry to provide more capacity and higher quality of service.
The term "4G" meaning the 4th Generation of wireless technology describes mobile wireless services which have been defined by the ITU's Radiocommunication Sector (ITU-R) and titled International Mobile Telecommunications-Advanced (IMT-Advanced). These are mobile systems that include the new capabilities of IMT that go beyond those of IMT-2000. Long Term Evolution-Advanced (LTE-Advanced) and IEEE 802.16m are the two main candidate technologies submitted for IMT-Advanced certification.
This thesis reviews the technology roadmap up to and including current 3G systems LTE from the 3rd Generation Partnership Project (3GPP) and IEEE 802.16e-2005 from the Institute of Electrical and Electronics Engineers (IEEE). Furthermore, new requirements and features for LTE-Advanced and IEEE 802.16m as well as a comparative approach towards IMT-Advanced certification are presented. Finally, the thesis concludes with a discussion on the market status and deployment strategies of LTE and IEEE 802.16e-2005, or Mobile WiMAX as it is being marketed
Handover evaluation of UMTS-WiMAX networks
Recently, data traffic movement through a wireless channel is assisted by suggesting and implementing many mechanisms, to achieve the speedy increasing importunity and popularity of the wireless networks. Various wireless technologies can be copulated to develop a heterogeneous network, which is a candidate towards (4G) networks. OPNET modeler (14.5) is used to design simulation modules of the heterogeneous network. During device connection between the worldwide interoperability for microwave access (WiMAX) and universal mobile telecommunication system (UMTS) networks, Performance metrics such as; Jitter end-to-end delay (E-2-E) Throughput is used. The results of the simulation are measured to determine the efficiency of the transfer using WiMAX-UMTS according to the selected metrics. The WiMAX-UMTS has shown valuable improvement in Process Durability, reduction of E-2-E delay, and Jitter. The maximum amount of data transfer and the least amount of delay and Jitter is at 250 sec. Because of the handover operations and data transfer momentum, the worst-case passes in the network when 618 sec is the minimum amount. The efficiency of throughput for WiMAX equal to 0.092666% as for the efficiency of throughput for UMTS equal to 4.633333*10-6 % whereas the E-2-E efficiency a delay equal to 0.5466%
Handover in Mobile WiMAX Networks: The State of Art and Research Issues
The next-generation Wireless Metropolitan Area
Networks, using the Worldwide Interoperability for Microwave
Access (WiMAX) as the core technology based on the IEEE
802.16 family of standards, is evolving as a Fourth-Generation
(4G) technology. With the recent introduction of mobility management
frameworks in the IEEE 802.16e standard, WiMAX
is now placed in competition to the existing and forthcoming
generations of wireless technologies for providing ubiquitous
computing solutions. However, the success of a good mobility
framework largely depends on the capability of performing fast
and seamless handovers irrespective of the deployed architectural
scenario. Now that the IEEE has defined the Mobile WiMAX
(IEEE 802.16e) MAC-layer handover management framework,
the Network Working Group (NWG) of the WiMAX Forum
is working on the development of the upper layers. However,
the path to commercialization of a full-fledged WiMAX mobility
framework is full of research challenges. This article focuses on
potential handover-related research issues in the existing and
future WiMAX mobility framework. A survey of these issues in
the MAC, Network and Cross-Layer scenarios is presented along
with discussion of the different solutions to those challenges. A
comparative study of the proposed solutions, coupled with some
insights to the relevant issues, is also included
Mobile Networks
The growth in the use of mobile networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications. Mobile networks require that the applications and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. Until the third generation of mobile networks, the need to ensure reliable handovers was still an important issue. On the eve of a new generation of access networks (4G) and increased connectivity between networks of different characteristics commonly called hybrid (satellite, ad-hoc, sensors, wired, WIMAX, LAN, etc.), it is necessary to transfer mechanisms of mobility to future generations of networks. In order to achieve this, it is essential to carry out a comprehensive evaluation of the performance of current protocols and the diverse topologies to suit the new mobility conditions
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