In this paper, we deal with user scheduling algorithms for a codebook based precoding of a multiuser multiple-input multiple-output (MIMO) downlink system considered in IEEE 802.16m and 3rd Generation Partnership Proj...
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ISBN:
(纸本)9781424425198
In this paper, we deal with user scheduling algorithms for a codebook based precoding of a multiuser multiple-input multiple-output (MIMO) downlink system considered in IEEE 802.16m and 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE) standardization. We especially focus on per-user unitary rate control (PU2RC) and semi-orthogonal user selection schemes. Also, we examine the disadvantage of the codebook based precoding with these schemes - a loss of sum-capacity when the codebook size is larger than the number of total users who request the communication service to a base station. Finally, we propose two user scheduling algorithms to improve the sum-capacity when the number of total users is smaller than the codebook size. First, we introduce feedback information retransmission algorithm in which each user sends a new codeword again depending on a request of the base station. Second, we address the adaptive feedback algorithm where users transmit one or two codeword indices called preferred matrix index (PMI) depending on their channel condition. The improvement of the sum-capacity is verified through the simulation.
Virtual machine technologies currently receive great interest both in industry and research communities. And it is one of the most important technologies for the coming Cloud Computing. We surveyed the CPU scheduling ...
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ISBN:
(纸本)9780769536781
Virtual machine technologies currently receive great interest both in industry and research communities. And it is one of the most important technologies for the coming Cloud Computing. We surveyed the CPU scheduling algorithms in Xen and VMWare systems, and found that both of them use a distinctive VCPUs running queue for each physical CPU, which is referred to Partition Queue Model (PQM) in this paper. As a contrast, a Sharing Queue Model (SQM) of CPU scheduling algorithm is proposed. The simulation experiments results show that the Sharing Queue Model of CPU scheduling achieves better performance than the Partition Queue Model and the deduction from Queue Theory also confirms the results. Moreover, with the CPU utilization increased, the advantage of Sharing Queue Model over Partition Queue Mode is more evident in response time.
This paper presents the performance analysis of several well-known partitioning scheduling algorithms in real-time and fault-tolerant multiprocessor systems. Both static and dynamic scheduling algorithms are analyzed....
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ISBN:
(纸本)9780769527246
This paper presents the performance analysis of several well-known partitioning scheduling algorithms in real-time and fault-tolerant multiprocessor systems. Both static and dynamic scheduling algorithms are analyzed. Partitioning scheduling algorithms, which are studied here, are heuristic algorithms that are formed by combining any of the bin-packing algorithms with any of the schedulability conditions for the Rate-Monotonic (RM) and Earliest-Deadline-First (EDF) policies. A tool is developed which enables to experimentally evaluate the performance of the algorithms from the graph of tasks. The results show that among several partitioning algorithms evaluated, the RM-Small-Task (RMST) algorithm is the best static algorithm and the EDF-Best-Fit (EDF-BF) is the best dynamic algorithm, for non fault-tolerant systems. For fault-tolerant systems which require about 49% more processors, the results show that the RM-First-Fit Decreasing Utilization (RM-FTDU) is the best static algorithm and the EDF-BF is the best dynamic algorithm. To decrease the number of processors in fault-tolerant systems, the RMST is modified. The results show that the modified RMST decreases the number of required processors between 7% and 78% in comparison with the original RMST, the RM-FTDU and other well-known static partitioning scheduling algorithms.
High-performance input queued switches achieve good performance with low cost. However, with the appearance of optical techniques, the line rate is much higher than before. scheduling algorithms require not only good ...
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ISBN:
(纸本)076951961X
High-performance input queued switches achieve good performance with low cost. However, with the appearance of optical techniques, the line rate is much higher than before. scheduling algorithms require not only good performance in delay and stability but fast speed and simple implementation as well. A variety of scheduling algorithms for Virtual Output Queuing (VOQ) packet switch architecture are proposed Round-robin scheduling algorithms are fast and simple to implement in hardware. In particular, a group of fully desynchronized round-robin scheduling algorithms- SRR (static round robin matching), proposed recently, achieve pretty good delay performance while easy to implement. However, they are not stable under non-uniform traffic. Randomized algorithms are stable under any admissible traffic, however their delay is high and hardware implementation is complex. Based on the concept of randomized algorithms and SRR, we propose a group of new scheduling algorithms, DRDSRR, the improved version of DRDSRR, ARDSRR and the variations of ARDSRR. They not only ensure stability but also have good performance and simple implementation. We have proved stability in the paper.
The queue size distribution and average waiting time for a time-shared system using round-robin (RR) scheduling, with and without overhead, are determined. In this study, the incoming processes are prioritized, and dy...
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ISBN:
(纸本)9781467367226
The queue size distribution and average waiting time for a time-shared system using round-robin (RR) scheduling, with and without overhead, are determined. In this study, the incoming processes are prioritized, and dynamic quantum times are assigned depending on the level of priority. With these parameters, RR versus priority dynamic quantum time round robin scheduling algorithm is analyzed to explore the effect of changing the quantum time of processes and determine the optimum context switches, turnaround time, and waiting time.
Grid scheduling problems are dynamic as the jobs and resources in the system vary overtime. The Rule-based scheduling algorithms are a new trend in grid scheduling which are applicable in dynamic grid environments;The...
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ISBN:
(纸本)9781424423576
Grid scheduling problems are dynamic as the jobs and resources in the system vary overtime. The Rule-based scheduling algorithms are a new trend in grid scheduling which are applicable in dynamic grid environments;The arriving jobs waiting for execution is ordered according to a certain rule and they are dispatched for processing according to that order. Grid scheduling algorithms usually involve more than one objective junction. In particular, it is not enough to minimize the Maximum completion time (Makespan) objective function without taking into consideration the lateness of the jobs (Tardiness). In this paper two novel dispatching rules are proposed that aims to minimize the maximum completion time of jobs (Makespan) and at the same time reduce the average lateness of these jobs (Tardiness). Furthermore, the proposed dispatching rules are combined with a local Tabu search algorithm that can be programmed to further optimize various grid scheduling objective functions. A complete set of comparison between the various combinations of techniques is presented based on simulation results obtained using Grid Sim.
We develop a family of distributed wireless scheduling algorithms that requires only O(1) complexity for M hop interference model, for any finite M. The recent technology advances and heterogeneity in wireless network...
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ISBN:
(纸本)9781424420742
We develop a family of distributed wireless scheduling algorithms that requires only O(1) complexity for M hop interference model, for any finite M. The recent technology advances and heterogeneity in wireless networks lead to various interference patterns. Thus, a scheduling algorithm geared into a specific interference model (typically one hop or two hop in literature) may be limited in its applicability. In this paper, we tackle this problem, and develop a family of scheduling algorithms (which guarantees throughput and delay performance) for M hop interference models. To achieve such a goal, we use the concept of vertex augmentation, and for a given M, the family of parameterized algorithms are proposed and the tradeoffs among throughput, complexity, and delay are studied.
Service Level Agreement (SLA) is one of the most important characteristics when discussing about Cloud scheduling. Modeling Cloud scheduling under SLA constraints represents one of the main research areas in the field...
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ISBN:
(纸本)9781538618394
Service Level Agreement (SLA) is one of the most important characteristics when discussing about Cloud scheduling. Modeling Cloud scheduling under SLA constraints represents one of the main research areas in the field of Cloud computing. One of the main ways to simulate the scheduling in the Cloud is by using a simulator that is verified by the academia and by the industry as one of the most accurate and capable of reproducing real scheduling situation. In this paper, we model scheduling in the Cloud under SLA constraints. Our model also attempts to achieve profit optimization. The model of the scheduling under SLA constraints and profit optimization is implemented and verified by using the features of the CloudSim simulator, a well-known Cloud simulator.
One proposed technique to reduce energy consumption of data centers is thermal-aware job scheduling, i.e. job scheduling that relies on predictive thermal models to select among possible job schedules to minimize its ...
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ISBN:
(纸本)9783642035463
One proposed technique to reduce energy consumption of data centers is thermal-aware job scheduling, i.e. job scheduling that relies on predictive thermal models to select among possible job schedules to minimize its energy needs. This paper investigates, using a more realistic linear cooling model, the energy savings of previously proposed thermal-aware job scheduling algorithms, which assume a less realistic model of constant cooling. The results show that the energy savings achieved are greater than the savings previously predicted. The contributions of this paper include: i) linear cooling models should be used in analysis and algorithm design, and ii) although the job scheduler must control the cooling equipment to realize most of the thermal-aware job schedule's savings. some savings can be still achieved without that control.
Assessing the performance of scheduling heuristics through simulation requires to generate synthetic instances of tasks and machines with well-identified properties. Carefully controlling these properties is mandatory...
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ISBN:
(纸本)9783662480960;9783662480953
Assessing the performance of scheduling heuristics through simulation requires to generate synthetic instances of tasks and machines with well-identified properties. Carefully controlling these properties is mandatory to avoid any bias. We consider the scheduling problem consisting of allocating independent sequential tasks on unrelated processors while minimizing the maximum execution time. In this problem, the instance is a cost matrix that specifies the execution cost of any task on any machine. This paper proposes a measure for quantifying the heterogeneity properties of a cost matrix. An analysis of two classical methods used in the literature reveals a bias in previous studies. A new method is proposed to generate instances with given heterogeneity properties and it is shown that they have a significant impact on several heuristics.
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