The mainstream dynamic bandwidth allocation (DBA) architectures for Ethernet Passive Optical Networks (EPONs) have employed two independent scheduling mechanisms in order to support quality of service: inter-ONU sched...
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The mainstream dynamic bandwidth allocation (DBA) architectures for Ethernet Passive Optical Networks (EPONs) have employed two independent scheduling mechanisms in order to support quality of service: inter-ONU scheduling (timeslot assignment) and intra-ONU scheduling (priority queuing). These architectures tend to implement the inter-ONU scheduling function at the OLT, whereas the intra-ONU scheduling function at the individual ONUs. Since these scheduling functions have been separated, these architectures cannot generally yield a globally optimized bandwidth allocation. In this paper, a centralized bandwidth allocation model is proposed that implements both the scheduling functions at the OLT. A credit pooling technique is employed that enables the OLT to partition the upstream bandwidth among different class of service queues, and to prevent ONUs from monopolizing the bandwidth. High network utilization is achieved by embedding ONU scheduling decisions in time and by eliminating the channel idle-time overhead, associated with many earlier DBA schemes.
We apply novel utility-based scheduling schemes to uplink single carrier frequency division multiple access (SC-FDMA) systems. Two utility functions are used for managing two dimensional resources (time and frequency)...
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We apply novel utility-based scheduling schemes to uplink single carrier frequency division multiple access (SC-FDMA) systems. Two utility functions are used for managing two dimensional resources (time and frequency): user data rate for maximizing system capacity and logarithmic user data rate for proportional fairness. To develop utility-based scheduling algorithms, we revise channel-dependent scheduling (CDS) schemes derived in our previous work (J. Lim et al.). The results show that proportional fair scheduling with logarithmic user data rate can improve the rate-sum capacity up to 100% for localized FDMA and 30% for interleaved FDMA, with the capacity gains equally shared among all users
While most parallel task graphs scheduling research has been done in the context of single homogeneous clusters, heterogeneous platforms have become prevalent and are extremely attractive for deploying applications at...
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While most parallel task graphs scheduling research has been done in the context of single homogeneous clusters, heterogeneous platforms have become prevalent and are extremely attractive for deploying applications at unprecedented scales. In this paper we address the need for scheduling techniques for parallel task applications for heterogeneous clusters of clusters by proposing a method to adapt existing parallel task graphs scheduling heuristics that have proved to be efficient on homogeneous environments. The contributions of this paper are: (i) a novel "virtual" cluster methodology for handling platform heterogeneity; (ii) a novel task placement step, designed to determine whether the placement step of heuristics for homogeneous platforms is adapted to the heterogeneous case; (iii) an empirical evaluation in a wide range of platform and application scenarios. This study shows that the proposed heuristics achieve better performance than the original when platform are heterogeneous and we discuss a number of trends apparent in our results
A hybrid electronic/optical packet switch consists of electronically buffered line-cards interconnected by an optical switch fabric. It provides a scalable switch architecture for next generation high-speed routers. D...
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A hybrid electronic/optical packet switch consists of electronically buffered line-cards interconnected by an optical switch fabric. It provides a scalable switch architecture for next generation high-speed routers. Due to the non-negligible switch reconfiguration overhead, many packet scheduling algorithms are invented to ensure performance guaranteed switching (i.e. 100% throughput with bounded packet delay), at the cost of speedup. In particular, minimum delay performance can be achieved if an algorithm can always find a schedule of no more than N configurations for any input traffic matrix, where N is the switch size. Various minimum delay scheduling algorithms (MIN, alpha i -SCALE and QLEF) are proposed. Among them, QLEF requires the lowest speedup bound. In this paper, we show that the existing speedup bound for QLEF is not tight enough. A new bound which is 10% lower than the existing one is derived.
Despite growing popularity of small-scale clusters built out of off-the-shelf components, there has been little research on how these small-scale clusters behave under different scheduling policies. Batch scheduling p...
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ISBN:
(纸本)9781424405015
Despite growing popularity of small-scale clusters built out of off-the-shelf components, there has been little research on how these small-scale clusters behave under different scheduling policies. Batch scheduling policies with backfilling provide excellent space-sharing strategy for parallel jobs. However, as the performances of uniprocessor and symmetric multiprocessor have improved with time-sharing scheduling strategies, it is intuitive that the performance of a cluster of PCs with distributed memory may also improve with time-sharing strategies, or a combination of time-sharing and space-sharing strategies. Apart from the batch scheduling policies, this research explores the possibilities of using synchronized time-sharing scheduling algorithms for clusters. This paper describes simulation of the Gang scheduling policies on top of an existing batch scheme. The simulation results indicate that time-sharing scheduler for clusters could exhibit superior performance over a batch policy
In this paper, a family of integer linear programs is formulated for performing collision free scheduling in Spatial-TDMA wireless mesh networks. We extend previous formulations for power aware STDMA scheduling to inc...
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In this paper, a family of integer linear programs is formulated for performing collision free scheduling in Spatial-TDMA wireless mesh networks. We extend previous formulations for power aware STDMA scheduling to include discrete power transmission and multi-rate support via adaptive constellation selection. Despite the theoretical attractiveness of these (mixed) integer linear programs, STDMA scheduling problems are in general intractable (NP-hard problems). Thus, the practicality of providing optimal solutions is rather limited. To this end, we study approximation algorithms that are based on linear programming relaxation and randomized rounding. Based on these approximation algorithms we focus our study on the trade-off between optimality of the solution and feasibility. Conducted numerical investigations aim to vindicate the claim regarding the strength of randomized algorithms. In that respect the performance of the approximation algorithms under different scenarios, such as the number of active links and number of nodes in the mesh network, is investigated.
The elastic task model (Buttazzo et al., 2002) is a powerful model for adapting real-time systems in the presence of uncertainty. This paper generalizes the existing elastic scheduling approach in several directions. ...
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The elastic task model (Buttazzo et al., 2002) is a powerful model for adapting real-time systems in the presence of uncertainty. This paper generalizes the existing elastic scheduling approach in several directions. It reveals that the original task compression algorithm in (Buttazzo et al., 2002) in fact solves a quadratic programming problem that seeks to minimize the sum of the squared deviation of a task's utilization from initial desired utilization. This finding indicates that the task compression algorithm may be applied to efficiently solve other similar types of problems. In particular, an iterative approach is proposed to solve the task compression problem for real-time tasks with deadlines less than respective periods. Furthermore, a new objective for minimizing the average difference of task periods from desired values is introduced and a closed-form formula is derived for solving the problem without recursion
We consider scheduling and resource allocation for the downlink of a OFDM-based wireless network. During each time-slot the scheduling and resource allocation problem involves selecting a subset of users for transmiss...
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We consider scheduling and resource allocation for the downlink of a OFDM-based wireless network. During each time-slot the scheduling and resource allocation problem involves selecting a subset of users for transmission, determining the assignment of available subcarriers to selected users, and for each subcarrier determining the transmission power and the coding and modulation scheme used. We address this in the context of a utility-based scheduling and resource allocation scheme presented in earlier papers. scheduling and resource allocation is determined by solving an optimization problem, which is convex for a reasonable model of the feasible rates. By exploiting the structure of this problem, we give optimal and sub-optimal algorithms for its solution. We provide simulation results comparing different algorithms and parameter settings.
In order to achieve high end-to-end throughput in a multihop wireless ad hoc network, TD/CDMA has been chosen as the medium access control (MAC) scheme due to its support for high network throughput in a multihop envi...
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In order to achieve high end-to-end throughput in a multihop wireless ad hoc network, TD/CDMA has been chosen as the medium access control (MAC) scheme due to its support for high network throughput in a multihop environment. The associated power control and scheduling problem needs to be addressed to optimize the operations of TD/CDMA. In this paper, cluster based architecture is introduced to provide centralized control within clusters, and the corresponding power control and scheduling schemes are derived to maximize a network utility function and guarantee the minimum rate required by each traffic session. Because the resulted optimal power control reveals bang-bang characteristics, i.e., scheduled nodes transmit with full power while other nodes remain silent, the joint power control and scheduling problem is reduced to a scheduling problem. In order to achieve a balance between throughput and fairness, proportional fair scheduling is considered. The multi-link version of the proportional fair scheduling algorithms for multihop wireless ad hoc networks are proposed. In addition, a generic token counter mechanism is employed to satisfy the minimum rate requirements. Approximation algorithms are suggested to reduce the computational complexity. In networks that are lack of centralized control, distributed scheduling algorithms are also derived and fully distributed implementation is provided. Simulation results demonstrate the effectiveness of the proposed schemes
Opportunistic transmission scheduling schemes improve system capacity by taking advantage of independent time varying channels in wireless networks. In the design of such scheduling schemes, the fairness criterion pla...
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Opportunistic transmission scheduling schemes improve system capacity by taking advantage of independent time varying channels in wireless networks. In the design of such scheduling schemes, the fairness criterion plays an important role in the tradeoff of total system capacity and the achievable throughput of individual users. To meet different fairness demands with a unified opportunistic scheduling scheme, in this paper, we have extended the well known opportunistic scheduling scheme PFS into αPFS, which satisfies arbitrary fairness demands, varying from proportional fairness to maxmin fairness, through adjusting the parameter α. To further improve the achievable diversity gains of αPFS, we extend the αPFS scheme into an αPFS-P scheme. Performances of αPFS and αPFS-P are studied and compared. As demonstrated in the simulation results, both αPFS and αPFS-P can achieve adjustable fairness criteria, varying from proportional fairness to max-min fairness. Compared with αPFS, αPFS-P achieves higher diversity gains with degraded short term performance, which is still better than the performance of PFS.
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