A bandwidth-limited wireless channel can considerably improve its performance by exploiting multiple-input-multiple-output (MIMO) antennas. Combining spatial multiplexing with multiuser diversity, we develop an optima...
详细信息
A bandwidth-limited wireless channel can considerably improve its performance by exploiting multiple-input-multiple-output (MIMO) antennas. Combining spatial multiplexing with multiuser diversity, we develop an optimal cross-layer scheduling mechanism that executes fair scheduling at the upper layer and optimal antenna assignment at the physical layer. For fair scheduling, we propose a framework that achieves the objective of maximum capacity and proportional fairness. For optimal antenna assignment, we consider the Hungarian algorithm that maximally utilizes the characteristics of MIMO systems by adopting the graph theoretical approach. Through simulations, we demonstrate the performance of the optimal scheduling.
There are many capacity enhancement techniques in wireless networks. Multiple-input-multiple-output (MIMO) antenna systems, channel-state based packet data scheduling algorithms and adaptive modulation and coding are ...
详细信息
There are many capacity enhancement techniques in wireless networks. Multiple-input-multiple-output (MIMO) antenna systems, channel-state based packet data scheduling algorithms and adaptive modulation and coding are examples of such techniques. In this paper, we provide the simulation results for various transmission schemes (including MIMO) in conjunction with a channel-state-based scheduling algorithm and an adaptive modulation and coding scheme Consequently, we demonstrate the cellular system capacity gain resulting from interaction between these three techniques. Specifically, system-level simulations are presented for the wideband CDMA (WCDMA) downlink shared channel.
In this paper, we present a new heuristic algorithm to schedule a set of independent stochastic tasks with parallelizable contents in multiprocessor systems. Each task is described by its deadline and its time cost di...
详细信息
In this paper, we present a new heuristic algorithm to schedule a set of independent stochastic tasks with parallelizable contents in multiprocessor systems. Each task is described by its deadline and its time cost distribution, which is given in terms of mean and variance. A scheduled task may run as one unit on a single processor or partitioned into k parallel parts running on k different processors. The proposed algorithm exploits parallelism in tasks, if it is necessary, and distributes them among the available processors to yield a high probability of meeting their deadlines and, hence obtain better schedulability
Stochastic scheduling problems are difficult stochastic control problems with combinatorial decision spaces. We focus on a class of stochastic scheduling problems, the quiz problem and its variations. We discuss the u...
详细信息
Stochastic scheduling problems are difficult stochastic control problems with combinatorial decision spaces. We focus on a class of stochastic scheduling problems, the quiz problem and its variations. We discuss the use of heuristics for their solution, and we propose rollout algorithms based on these heuristics which approximate the stochastic dynamic programming algorithm. We show how the rollout algorithms can be implemented efficiently, with considerable savings in computation over optimal algorithms. We delineate circumstances under which the rollout algorithms are guaranteed to perform better than the heuristics on which they are based. We also show computational results which suggest that the performance of the rollout policies is near-optimal, and is substantially better than the performance of their underlying heuristics.
We consider the problem of power controlled minimum frame length scheduling for TDMA wireless networks. Given a set of one-hop transmission requests, our objective is to schedule them in a minimum number of time slots...
详细信息
We consider the problem of power controlled minimum frame length scheduling for TDMA wireless networks. Given a set of one-hop transmission requests, our objective is to schedule them in a minimum number of time slots, so that each slot schedule is free of self-interferences and meets desired SINR constraints. Additionally, the transmit power vector corresponding to each slot schedule should be minimal. We consider two different versions of the problem, a per-slot version and a per-frame version, and develop mixed integer linear programming models which can be used for solving the problems optimally. In addition, we propose a heuristic algorithm for the per-slot version.
The credibility measure of fuzzy events is a relatively new concept related to fuzzy variable. This paper aims at demonstrating how this concept can be used for managing fuzzy scheduling on flow-shop problems. Three t...
详细信息
ISBN:
(纸本)0780378105
The credibility measure of fuzzy events is a relatively new concept related to fuzzy variable. This paper aims at demonstrating how this concept can be used for managing fuzzy scheduling on flow-shop problems. Three types of fuzzy flow-shop scheduling models are presented. A hybrid intelligent algorithm is then designed to solve the proposed fuzzy flow-shop scheduling models. Computation experiments are provided to illustrate its effectiveness.
Digital broadcasting can now be used for the transmission of not only video data but also IP data for http and FTP services. ATM over MPEG2-TS protocol stack is examined as one of the technologies that allows MPEG2-TS...
详细信息
Digital broadcasting can now be used for the transmission of not only video data but also IP data for http and FTP services. ATM over MPEG2-TS protocol stack is examined as one of the technologies that allows MPEG2-TS to offer efficient and flexible multiplexing. We have already proposed a scheduling discipline that is simple enough to implement in hardware and adaptively generates MPEG2-TS packets from the incoming ATM cells. This paper shows the results of our evaluation (simulations) into its efficiency in terms of multiplexing gain, delay performance, and fairness. The proposed scheduling discipline is found to be superior to the alternatives with respect to the multiplexing gain while offering excellent delay and fairness characteristics.
The introduction of packet switched data in cellular systems requires new radio resource algorithms. For example, a scheduling algorithm is needed when more than one user may share the same physical channel, to determ...
详细信息
The introduction of packet switched data in cellular systems requires new radio resource algorithms. For example, a scheduling algorithm is needed when more than one user may share the same physical channel, to determine the order in which users on the same channel should be allowed to transmit. This paper discusses the scheduling problem in general, and investigates the performance of three basic scheduling algorithms in an enhanced data rates for global GSM evolution/general packet radio service (EDGE/GPRS) system. Effort has been spent on modeling the bursty interference of a packet data network and using appropriate performance measures for the evaluation of such a network. The results indicate that the choice of scheduling discipline is very important, especially in a highly loaded system. With the performance measures used here, it is more important to consider the packet sizes than the users' different channel qualities.
Time-critical jobs in many real-time applications have more than one feasible interval. Such jobs can be executed in any of their feasible intervals. Given a Multiple Feasible Interval (MFI) job set that is schedulabl...
详细信息
ISBN:
(纸本)9781424449316
Time-critical jobs in many real-time applications have more than one feasible interval. Such jobs can be executed in any of their feasible intervals. Given a Multiple Feasible Interval (MFI) job set that is schedulable, energy can be saved by carefully selecting the executing interval for each job. In this paper, we explore the energy minimization problem for real-time systems in which jobs have multiple feasible intervals. The static and dynamic energy management schemes are both investigated to minimize the energy consumption while preserving the system's feasibility. Focusing on the EDF scheduling algorithm, we first study reducing the dynamic power consumption. We show that the static optimal speed assignment problem is NP-Hard and propose a Simulated Annealing (SA) based approach to solve it. Then, we develop an on-line greedy algorithm to exploit the runtime slacks by "fetching" the eligible job from a hot spot to execute earlier, thus, reducing the dynamic energy consumption. In addition, a leakage-aware version is discussed to improve the overall energy efficiency as well. Simulation results show that all the proposed schemes can achieve significant improvements on energy efficiency while the system remains schedulable.
暂无评论