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609
Fair Scheduling in Wireless Packet Networks
- IEEE/ACM Transactions on Networking
, 1997
"... Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair scheduling algorithms because of two unique characteristics of wireless media: (a) bursty channel errors, and (b) location-dependent channel capacity and e ..."
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Cited by 339 (21 self)
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Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair scheduling algorithms because of two unique characteristics of wireless media: (a) bursty channel errors, and (b) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however a base station has only a limited knowledge of the arrival processes of uplink flows. In this paper, we propose a new model for wireless fair scheduling based on an adaptation of fluid fair queueing to handle location-dependent error bursts. We describe an ideal wireless fair scheduling algorithm which provides a packetized implementation of the fluid model while assuming full knowledge of the current channel conditions. For this algorithm, we derive the worst-case throughput and delay bounds. Finally, we describe a practical wir...
Internet QoS: A Big Picture
, 1999
"... In this article we present a framework for the emerging Internet quality of service (QoS). All the important components of this framework --- integrated services, RSVP, differentiated services, multiprotocol label switching (MPLS), and constraintbased routing --- are covered. We describe what integr ..."
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Cited by 287 (2 self)
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In this article we present a framework for the emerging Internet quality of service (QoS). All the important components of this framework --- integrated services, RSVP, differentiated services, multiprotocol label switching (MPLS), and constraintbased routing --- are covered. We describe what integrated services and differentiated services are, how they can be implemented, and the problems they have. We then describe why MPLS and constraint-based routing have been introduced into this framework, how they differ from and relate to each other, and where they fit into the differentiated services architecture. Two likely service architectures are presented, and the end-to-end service deliveries in these two architectures are illustrated. We also compare ATM networks to router networks with differentiated services and MPLS. Putting all these together, we give the readers a grasp of the big picture of the emerging Internet QoS. 12 IEEE Network . March/April 1999 9 and differenti...
Opportunistic transmission scheduling with resource-sharing constraints in wireless networks
- IEEE Journal on Selected Areas in Communications
, 2001
"... We present an “opportunistic ” transmission scheduling policy that exploits time-varying channel conditions and maxi-mizes the system performance stochastically under a certain resource allocation constraint. We establish the optimality of the scheduling scheme, and also that every user experiences ..."
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Cited by 220 (10 self)
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We present an “opportunistic ” transmission scheduling policy that exploits time-varying channel conditions and maxi-mizes the system performance stochastically under a certain resource allocation constraint. We establish the optimality of the scheduling scheme, and also that every user experiences a performance improvement over any non-opportunistic scheduling policy when users have independent performance values. We demonstrate via simulation results that the scheme is robust to es-timation errors, and also works well for nonstationary scenarios, resulting in performance improvements of 20–150 % compared with a scheduling scheme that does not take into account channel conditions. Last, we discuss an extension of our opportunistic scheduling scheme to improve “short-term ” performance.
Efficient network QoS provisioning based on per node traffic shaping
- IEEE/ACM Transaction on Networking
, 1996
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Proportional Differentiated Services: Delay Differentiation and Packet Scheduling
- IEEE/ACM Transactions on Networking
, 1999
"... The proportional differentiation model provides the network operator with the `tuning knobs' for adjusting the per-hop quality-of-service (QoS) ratios between classes, independent of the class loads. This paper applies the proportional model in the differentiation of queueing delays, and invest ..."
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Cited by 183 (6 self)
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The proportional differentiation model provides the network operator with the `tuning knobs' for adjusting the per-hop quality-of-service (QoS) ratios between classes, independent of the class loads. This paper applies the proportional model in the differentiation of queueing delays, and investigates appropriate packet scheduling mechanisms. Starting from the proportional delay differentiation (PDD) model, we derive the average queueing delay in each class, show the dynamics of the class delays under the PDD constraints, and state the conditions in which the PDD model is feasible. The feasibility model of the model can be determined from the average delays that result with the strict priorities scheduler. We then focus on scheduling mechanisms that can implement the PDD model, when it is feasible to do so. The proportional average delay (PAD) scheduler meets the PDD constraints, when they are feasible, but it exhibits a pathological behavior in short timescales. The waiting time priority (WTP) scheduler, on the other hand, approximates the PDD model closely, even in the short timescales of a few packet departures, but only in heavy load conditions. PAD and WTP serve as motivation for the third scheduler, called hybrid proportional delay (HPD). HPD approximates the PDD model closely, when the model is feasible, independent of the class load distribution. Also, HPD provides predictable delay differentiation even in short timescales.
Exact admission control in networks with bounded delay services
- IEEE/ACM TRANSACTIONS ON NETWORKING
, 1996
"... To support the requirements for the transmission of continuous media, such as audio and video, multiservice packet switching networks must provide service guarantees to connections, including guarantees on throughput, network delays, and network delay variations. For the most demanding applications, ..."
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Cited by 177 (19 self)
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To support the requirements for the transmission of continuous media, such as audio and video, multiservice packet switching networks must provide service guarantees to connections, including guarantees on throughput, network delays, and network delay variations. For the most demanding applications, the network must offer a service which can provide deterministic guarantees for the maximum delay ofpackets from all connections, referred to as bounded delay service. The admission control functions in a network with a bounded delay service must have available schedulability conditions that detect violations of delay guarantees in a network switch. In this study, exact schedulability conditions are presented for packet switches which transmit packets based on an Earliest-Deadline-First (EDF) or a Static-Priority (SP) algorithm. The schedulability conditions are given in terms of a general traffic model, making the conditions applicable to a large class of traffic specifications. A comparison of the new schedulability conditions with existing, less accurate, conditions show the e ciency gain obtained by using exact conditions. Examples are presented that show how the selection of a particular traffic specification and a schedulability condition impact the efficiency of a bounded delay service.
Trade Offs in the Design of a Router with Both Guaranteed and Best-Effort Services for Networks on Chips
, 2003
"... Managing the complexity of designing chips containing billions of transistors requires decoupling computation from communication. For the communication, scalable and compositional interconnects, such as networks on chip (NoC), must be used. In this paper we show that guaranteed services are essentia ..."
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Cited by 149 (14 self)
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Managing the complexity of designing chips containing billions of transistors requires decoupling computation from communication. For the communication, scalable and compositional interconnects, such as networks on chip (NoC), must be used. In this paper we show that guaranteed services are essential in achieving this decoupling. Guarantees typically come at the cost of lower resource utilization. To avoid this, they must be used in combination with best-effort services. The key element of our NoC is a router consisting conceptually of two parts: the so-called guaranteed throughput (GT) and best-effort (BE) routers. We combine the GT and BE router architectures in an efficient implementation by sharing resources. We show the trade offs between hardware complexity and efficiency of the combined router, and motivate our choices. Our reasoning for the trade offs is validated with a prototype router implementation. We show a lay-out of an inputqueued wormhole 5 x 5 router with an aggregate bandwidth of 80 Gbit/s. It occupies 0.26 mm² in CMOS12. This shows that our router provides high performance at reasonable cost, bringing NoCs one step closer.
A Hierarchical Fair Service Curve Algorithm for Link-Sharing, Real-Time and Priority Services
"... In this paper, we study hierarchical resource management models and algorithms that support both link-sharing and guaranteed real-time services with decoupled delay (priority) and bandwidth allocation. We extend the service curve based QoS model, which defines both delay and bandwidth requirements o ..."
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Cited by 146 (12 self)
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In this paper, we study hierarchical resource management models and algorithms that support both link-sharing and guaranteed real-time services with decoupled delay (priority) and bandwidth allocation. We extend the service curve based QoS model, which defines both delay and bandwidth requirements of a class, to include fairness, which is important for the integration of real-time and hierarchical linksharing services. The resulting Fair Service Curve linksharing model formalizes the goals of link-sharing and realtime services and exposes the fundamental tradeoffs between these goals. In particular, with decoupled delay and bandwidth allocation, it is impossible to simultaneously provide guaranteed real-time service and achieve perfect link-sharing. We propose a novel scheduling algorithm called Hierarchical Fair Service Curve (H-FSC) that approximates the model closely and efficiently. The algorithm always guarantees the performance for leaf classes, thus ensures real-time services, while minimizing the discrepancy between the actual services provided to the interior classes and the services defined by the Fair Service Curve link-sharing model. We have implemented the H-FSC scheduler in the NetBSD environment. By performing simulation and measurement experiments, we evaluate the link-sharing and real-time performances of H-FSC, and determine the computation overhead.
QoS Performance of Optical Burst Switching in IP-Over-WDM Networks
- IEEE Journal on Selected Areas in Communications
, 2000
"... We address the issue of how to provide basic quality of service (QoS) in optical burst-switched WDM networks with limited fiber delay lines (FDLs). Unlike existing buffer-based QoS schemes, the novel offset-time-based QoS scheme we study in this paper does not mandate any buffer for traffic isolatio ..."
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Cited by 134 (4 self)
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We address the issue of how to provide basic quality of service (QoS) in optical burst-switched WDM networks with limited fiber delay lines (FDLs). Unlike existing buffer-based QoS schemes, the novel offset-time-based QoS scheme we study in this paper does not mandate any buffer for traffic isolation, but nevertheless can take advantage of FDLs to improve QoS. This makes the proposed QoS scheme suitable for the next generation Optical Internet. The offset times required for class isolation when making wavelength and FDL reservations are quantified, and the upper and lower bounds on the burst loss probability are analyzed. Simulations are also conducted to evaluate the QoS performance in terms of burst loss probability and queuing delay. We show that with limited FDLs, the offset-time-based QoS scheme can be very efficient in supporting basic QoS.
QoS Routing in Networks with Uncertain Parameters
- IEEE/ACM Transactions on Networking
, 1998
"... Qo!3 requirements across networks, when the information available for ma:king routing decisions is inaccurate. This uncertainty about the actual stale of a network component arises naturally in a number of different environments, which are reviewed in the paper. The goal of the route selection proce ..."
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Cited by 126 (10 self)
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Qo!3 requirements across networks, when the information available for ma:king routing decisions is inaccurate. This uncertainty about the actual stale of a network component arises naturally in a number of different environments, which are reviewed in the paper. The goal of the route selection process is then to identify a path that is most likely to satisfy the QoS re-quirements. For end-to-end delay guarantees, this problem is intractable. However, we show that by decomposing the end-to-end constraint into local delay constraints, efficient and tractable solutions can be established. ‘We first consider the simpler problem of decomposing the end-to-end
