36 research outputs found
Qualidade de serviço em redes de acesso IEEE 802.16
Mestrado em Engenharia ElectrĂłnica e TelecomunicaçÔesA procura de serviços e de aplicaçÔes com elevadas exigĂȘncias de largura de
banda, e a vontade crescente para aceder a este tipo de serviços em qualquer
lugar, torna necessåria a integração da Internet actual com as redes móveis de
prĂłxima geração. No entanto, existirĂŁo sempre Ă reas remotas onde o acesso Ă
Internet, e nomeadamente a serviços de banda larga, serĂĄ difĂcil de conseguir.
O protocolo IEEE 802.16 Ă© uma tecnologia de banda larga sem fios que pode
ser usada neste tipo de cenårios. Esta dissertação apresenta uma arquitectura
de rede capaz de suportar serviços de tempo real com integração de QoS em
ambientes IPv6 através da utilização de redes IEEE 802.16. Nomeadamente, a
arquitectura definida suporta o acesso dinĂąmico e rĂĄpido por parte dos
terminais móveis aos serviços de rede, tal como reservas e modificaçÔes
dinĂąmicas de serviços de tempo real, caracterĂstica essencial para o suporte
de alta mobilidade. Para além disto, a solução proposta fornece também
suporte IPv6 e diferenciação de serviços direccionados para o mesmo terminal
mĂłvel.
Esta dissertação apresenta a arquitectura desenvolvida, os módulos
necessårios para a integração da tecnologia IEEE 802.16 num ambiente de
próxima geração, a implementação desses módulos para a construção de uma
rede real, e testes para avaliar o desempenho da rede em termos de QoS num
ambiente de rede de acesso mista, composta por IEEE 802.16 e IEEE 802.11.
São também efectuados testes de mobilidade para avaliar o desempenho da
solução descrita neste tipo de ambientes. Os resultados obtidos com a
arquitectura desenvolvida mostram que a arquitectura pode fornecer QoS fima-
fim sobre a concatenação de redes metropolitanas e locais, com suporte de
mobilidade.The growing demand of high bandwidth services and applications, and the
increasing will of access to these services anywhere, is motivating the
requirement to integrate the current Internet with the future mobile networks.
However, there will always be remote areas where Internet access will be
difficult to achieve. The IEEE 802.16 is an attractive broadband wireless
technology for these scenarios, non-withstanding its limitations for dynamic
environments.
This Thesis discusses a network architecture able to support IPv6 QoS aware
real time services using 802.16 networks. Specifically, this solution supports
dynamic and fast access from the Mobile Nodes to the network services, as
well as dynamic reservations and modifications of services. These fast and
dynamic reservations are crucial to the support of fast mobility approaches.
Moreover, the proposed solution is also able to provide IPv6 support and
efficient traffic differentiation for services running on the same MN.
This Thesis presents the envisioned architecture, the modules required to
provide the integrated QoS approach over the 802.16 network, the
implementation of the modules to build a real network, and address main
implementation results in terms of QoS performance, and in terms of mobility
with QoS support for converged networks comprising WiMAX and Wi-Fi
technologies. The obtained results show that our architecture is able to provide
end-to-end QoS over the concatenation of metro and local area networks, and
that seamless mobility is achieved with high performance measures, thus being
able to support real-time services
Adaptive load balancing routing algorithms for the next generation wireless telecommunications networks
This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel UniversityWith the rapid development of wireless networks, mesh networks are evolving as a new important technology, presenting a high research and commercial interest. Additionally, wireless mesh networks have a wide variety of applications, offering the ability to provide network access in both rural and urban areas with low cost of maintenance. One of the main functionalities of a wireless mesh network is load balancing routing, which is the procedure of finding the best, according to some criteria, routes that data need to follow to transfer from one node to another. Routing is one of the state-of-the-art areas of research because the current algorithms and protocols are not efficient and effective due to the diversity of the characteristics of these networks. In this thesis, two new routing algorithms have been developed for No Intra-Cell Interference (NICI) and Limited Intra-Cell Interference (LICI) networks based on WiMAX, the most advanced wireless technology ready for deployment. The algorithms created are based on the classical Dijkstra and Ford-Fulkerson algorithms and can be implemented in the cases of unicast and multicast transmission respectively.State scholarships foundation of Greece
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Investigation of efficient resource allocation schemes for WiMAX networks
This thesis was submitted for the degree of Master of Philosophy and was awarded by Brunel University on 9 July 2008.WiMax (Worldwide Interoperability for Microwave Access) is a promising wireless technology with the aim of providing the last mile wireless broadband access designed for both fixed and mobile consumers as an alternative solution to the wired DSL and cable access schemes. The purpose of this research project is to investigate efficient resource allocation algorithms for WiMax. To achieve this goal, we investigate efficient PHY layer Partial Usage of SubCarriers (PUSC) allocation as well as MAC layer piggyback bandwidth request mechanisms. At the PHY layer we proposed improvements on the Uplink and Downlink PUSC subcarrier allocation scheme. For the Uplink PUSC we suggested a method by allocating different frequencies to neighbouring cells in combination with the Integer Frequency Reuse (IFR) and Fractional Frequency Reuse (FFR) in order to reduce interferences and collisions. The simulation results exhibit that collision rates can be reduced to zero for both IFR and FFR patterns with the proposed improvement by assuming that perfect power control is used in the system. In addition, there is no collision at cell edges. The results also show that FFR patterns achieve lower inter-cell interference and higher capacities as compared to the IFR patterns. For the Downlink PUSC we introduced an offset scheme with the purpose of increasing the number of users in the system. At the MAC layer we propose an improvement on the piggyback bandwidth request mechanism by increasing the size of the piggyback bandwidth request in order to reduce the number of bandwidth requests and hence improve the resource utilisation. The simulation results demonstrate that our improved scheme achieves higher throughput, less delay and packet loss rates as compared to the standardised piggyback bandwidth request mechanism
Security-centric analysis and performance investigation of IEEE 802.16 WiMAX
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A Survey on Scheduling in IEEE 802.16 Mesh Mode
Cataloged from PDF version of article.IEEE 802.16 standard (also known as WiMAX)
defines the wireless broadband network technology which aims
to solve the so called last mile problem via providing high
bandwidth Internet even to the rural areas for which the cable
deployment is very costly. The standard mainly focuses on the
MAC and PHY layer issues, supporting two transmission modes:
PMP (Point-to-Multipoint) and mesh modes. Mesh mode is an
optional mode developed as an extension to PMP mode and it
has the advantage of having an improving performance as more
subscribers are added to the system using multi-hop routes. In
802.16 MAC protocol, mesh mode slot allocation and reservation
mechanisms are left open which makes this topic a hot research
area. Hence, the focus of this survey will mostly be on the mesh
mode, and the proposed scheduling algorithms and performance
evaluation methods
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
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