Due to the scarce wireless spectrum, the decision of call admission becomes an important work when a mobile call requests for bandwidth in cellular networks. A prediction system which can predict most information, such as system utilization and CDP and a CAC scheme which uses the prediction information generated by the proposed predicted system are proposed in this paper. Our proposed prediction system can provide prediction information in advance, whether the repetitive time series pattern of the information exists or not. A simple scheme that requires less resource has been used to generate prediction values, before the repetitive patterns have been found. The proposed CAC scheme is based on the prediction results and the bandwidth consumptions in the adjacent cell for deciding to admit a new call or not. The throttle flag that indicates the usage of current cell is proposed to prevent the newly admitted call request being blocked in the adjacent if handoff needed. In order to simplify the complexity of implementation and avoid computations being extremely riveted on the mobile switch center (MSC), an agent which consists of the prediction module and the CAC algorithm is implemented in each cell, and the statistics of each agent can be gathered and analyzed by the central unit. The simulation results show that the proposed CAC scheme can maintain CDP below a predefined threshold, and the CBP is lower than traditional guard channel policies.
the grid computing system can support execution of computationally intensive parallel and distributed applications. The main characteristics of grid computing system are similar to the heterogeneous computing system, except the fluctuant transfer rate. A dynamic scheduling algorithm, called Dynamic HEFT (DH) algorithm is proposed in this paper to enhance the functions of the original static HEFT (SH) algorithm. Instead of dispatching tasks to physical processors directly, the DH algorithm dispatches tasks to multiple queues. During runtime, the DH algorithm continues to dispatch the scheduled tasks to corresponding physical processor and predicts the transfer rate. Once the difference between two consecutive transfer rates is greater than the threshold value, rescheduling will be performed. The experimental results show that the proposed DH algorithm performs better than the SH algorithm in the system, especially under the grid computing environment, with fluctuant transfer rate and high bandwidth differences.
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