| عنوان فارسی مقاله: | بررسی پروتکل مسیریابی پشتیبانی کیفیت خدمات QoS در شبکه های ادهاک متحرک |
| عنوان انگلیسی مقاله: | A Survey of Routing Protocols that Support QoS in Mobile Ad Hoc Networks |
| دانلود مقاله انگلیسی: | برای دانلود رایگان مقاله انگلیسی با فرمت pdf اینجا کلیک نمائید |
| خرید ترجمه آماده: | تماس بگیرید |
| کد مقاله | s10 |
| سال انتشار | 2007 |
| تعداد صفحات مقاله انگلیسی | 9 |
| تعداد صفحات ترجمه مقاله | 29 |
| مجله | شبکه |
| دانشگاه | روچستر |
| کلمات کلیدی | ندارد |
| نشریه | IEEE |
بخشی از ترجمه:
چکیده
رشد فزاینده استفاده از دستگاه های سیار که با خواست کاربران برای کاربردهای بلادرنگ همراه شده است چالش های جدیدی را برای طراحی شبکه های اد هاک سیار بوجود می آورد. مهمترین این چالشها در فعال سازی برنامه های کاربردی برای شبکه های مخابراتی hoc ad ایجاد پشتیبان برای کیفیت سرویس (QoS) میباشد، همانند تطابق پهنای باند یا قیود تاخیر. بخصوص، اینکه مسیریابی پروتکلها در تطابق با ماتریس های کیفیت در مسیریابی و حفظ برای QoS سر به سر قرار بگیرد اهمیت بسزایی دارد. این مقاله بطور گسترده و خاص بر روی موضوعاتی مشتمل بر مسیریابی کیفیت سرویس مطالعه کرده و یک دید کلی و مقایسه با پروتکلهای مسیریابی کیفیت سرویس مطالعاتی ارائه میدهد. علاوه بر آن، موضوع باز که باید برای پشتیبانی کامل مسیریابی کیفیت سرویس آدرس دهی شوند مورد بحث قرار گرفته است.
وجه تمایز شبکه های سیار و hoc adMANET با انواع دیگر شبکه ها بواسطه مشخصه فیزیکی، قالب سازمان دهی شده و توپولوژی دینامیکی آنها میباشد:
مشخصات فیزیکی: کانالهای بیسیم عمدتا به دلیل تاثیراتی از قبیل محو شدگی چند مسیره، تداخل و مانع شدن و ایجاد پهنای باند لینک پیش بینی نشده و بسته تاخیری مستعد خطا هستند.
فرمت سازمان دهی شده: طبیعت توزیعی MANETها بدین معنی است که منابع کانال اصلی را نمیتوان در یک روش از پیش تعیین شده ای معین کرد.
بخشی از مقاله انگلیسی:
Mobile ad hoc networks (MANETs) are distinguishedfrom other types of networks by theirphysical characteristics, organizational format,and dynamic topology:• Physical characteristics: Wireless channels are inherentlyerror-prone, due to effects such as multipath fading, interference,and shadowing; causing unpredictable link bandwidthand packet delay.• Organizational format: The distributed nature of MANETsmeans that channel resources cannot be assigned in a predeterminedway.• Dynamic topology: As hosts in a MANET are mobile, linksare created and destroyed in an unpredictable way. Therefore,the network status can change quickly, causing hoststo have imprecise knowledge of the current network state.Because of device mobility in MANETs and the sharednature of the wireless medium, offering guaranteed quality ofservice (QoS), such as bandwidth, delay, delay jitter, andpacket delivery ratio, is not practical. Therefore, soft QoS andQoS adaptation are proposed instead. Soft QoS implies thatfailure to meet QoS is allowed, for example, when routesbreak or the network becomes partitioned [1]. However, if anetwork changes too fast to propagate the topology statusinformation, it is challenging to offer even soft QoS. Therefore,combinatorial stability — which means that given a specifictime window topology changes occur sufficiently slowly toallow successful propagation of all topology updates as necessary[2] — must be met in order to provide QoS.Certain applications, such as real-time applications that canoptimize their performance based on feedback about networkresource availability, can benefit from QoS adaptation. Forexample, layered coding allows enhanced layers of differentquality levels to be transmitted, provided a minimum bandwidthis guaranteed for transmitting the base layer. By providingfeedback to the application about available resources, theapplication can alter its coding strategy to provide the bestquality for the current resource limitations.Routing is used to set up and maintain routes betweennodes to support data transmission. Early MANET routingprotocols focused on finding a feasible route from a source toa destination, without any consideration for optimizing theutilization of network resources or for supporting specificapplication requirements. To support QoS, the essential problemis to find a route with sufficient available resources tomeet the QoS constraints and possibly to incorporate optimizations,such as finding the lowest cost or most stable of theroutes that meet the QoS constraints. Given these goals, thefollowing are the basic design considerations for a QoS-awarerouting protocol.• Resource estimation: To offer a resource-guaranteed route,the key concept is to obtain information about the availableresources from lower layers. This information helps in performingcall admission and QoS adaptation. Most existingtechniques focus on bandwidth and/or delay QoS constraints,and thus, the bandwidth available to a node or linkand/or the delay must be estimated. In MANETs, hostsshare the bandwidth with their neighbor hosts, and thus,the bandwidth available to a node varies and is dynamicallyaffected by the traffic of its neighbors. Therefore, the twokey problems in bandwidth estimation are: how exactly toestimate the available bandwidth and how frequently toestimate it. In general, the trade-off between the benefitfrom using resource estimation and the cost in terms ofoverhead and computing resources used for resource estimationis a key issue.• Route discovery: There are two main approaches to routingin MANETs: reactive routing and proactive routing. Reactiverouting reduces overhead at the expense of delay infinding a suitable route; whereas, the reverse is true forproactive routing. For QoS-aware routing, another issue isdetermining the combination of reduced latency andreduced overhead that is best for supporting QoS.• Resource reservation: As previously stated, the bandwidthresources are shared by neighboring hosts in MANETs.Therefore, another challenging issue is how to allocatethese shared resources, the type of resource reservationscheme, and the kind of call admission that should be usedfor setting up and maintaining QoS-aware routes.• Route maintenance: The mobility of nodes in MANETscauses frequent topology changes in the network, making itdifficult to meet the QoS constraints. Incorporating a fastroute maintenance scheme into QoS-aware routing is thefourth design consideration. The typical approach to routemaintenance, which entails waiting for the host to discovera route break, significantly affects the routing performance.Therefore, a prediction scheme or redundant routing ishelpful to assist in route maintenance.• Route selection: QoS-aware routing has more stringentrequirements on route stability, because frequent route failuresadversely affect the end-to-end QoS. Thus, in somesense the route with the largest available bandwidth is notthe only consideration — other metrics such as route reliabilityand route length also should be considered whenselecting a suitable route for a QoS-aware routing protocol.Several routing protocols have beeen developed that supportQoS in one or more of the following ways:• Choosing routes with the largest available bandwidth (orminimum delay)• Providing a call admission feature to deny route requests ifinsufficient bandwidth is available to support the request• Providing feedback to the application about available bandwidthresources or route delay estimationSeveral researchers [3–5] addressed the general problem ofQoS in MANETs, providing overviews and insights on thework being done in this area. In our article, we extensivelyand exclusively study the challenges in supporting QoS at thenetwork layer, as opposed to [3], which discusses the broadtopic of QoS support in MANETs, covering multiple layers,and thus does not provide an in-depth look at the networklayer and [4], which focuses on the medium access control(MAC) layer. Thus, the major new contributions of this articleare the focus on and in-depth studying of the issues involvedwith QoS-aware routing and the overview and comparison ofexisting QoS-aware routing protocols.In the next section, we provide high-level descriptions ofseveral QoS-aware routing protocols. Following this, we presenta comparison of these protocols and point out the openresearch issues in QoS-aware routing.
| عنوان فارسی مقاله: | بررسی پروتکل مسیریابی پشتیبانی کیفیت خدمات QoS در شبکه های ادهاک متحرک |
| عنوان انگلیسی مقاله: | A Survey of Routing Protocols that Support QoS in Mobile Ad Hoc Networks |
| دانلود مقاله انگلیسی: | برای دانلود رایگان مقاله انگلیسی با فرمت pdf اینجا کلیک نمائید |
| خرید ترجمه آماده: | تماس بگیرید |
| کد مقاله | s10 |