The more-less (ML) scheme has been shown to be an efficient approach for maintaining temporal consistency of real-time data objects. Although ML provides a deterministic guarantee in temporal consistency, the number of update transactions that can be supported in a system is limited. This is due to its use of the worst-case computation time in deriving deadlines and periods of update transactions. This paper studies the problem of temporal consistency maintenance where a certain degree of temporal inconsistency is tolerable. A suite of statistical more-less (SML) approaches are proposed to explore the trade-off between quality of service (QoS) of temporal consistency and the number of supported transactions. It begins with a baseline algorithm, SML-BA, which provides the requested QoS of temporal consistency. Then, SML with optimization (SML-OPT) is proposed to further improve the QoS by better utilizing the excess processor capacity. Finally, SML-OPT is enhanced with a slack reclaiming scheme (SML-SR). The reclaimed slacks are used to process jobs whose required computation time is larger than the guaranteed computation time. Simulation experiments are conducted to compare the performance of these schemes (SML-BA, SML-OPT, and SML-SR) together with the deterministic more-less and half-half schemes. The results show that the SML schemes are effective in trading the schedulability of transactions for the QoS guaranteed. Moreover, SML-SR performs best and offers a significant QoS improvement over SML-BA and SML-OPT.

This paper studies the location management problem in cellular wireless networks. We propose a handoff-velocity prediction (HVP) scheme to minimize the paging cost in searching a mobile terminal. HVP is based on the assumptions that the movement behavior of mobile terminals has temporal and spatial properties. Based on handoff statistics the system maintains a handoff graph to describe the movement probabilities of a mobile terminal in a cell to the neighboring cells within a location area. Combining with the velocity information of a mobile terminal we calculate the probabilities of finding the mobile terminal in the cells within the paging area. Then, the paging of the mobile terminal follows the cell probabilities to minimize the paging cost of a mobile terminal. Analysis on HVP has been performed to calculate the optimal threshold for update generation to minimize the total cost in location management. A group paging scheme based on a non-linear programming technique is suggested to limit the paging delay within the quality of services (QoS) requirement in call connection delay and at the same time to minimize the paging cost. In 3G networks and the next generation wireless networks different connection requests may have different QoS requirements in connection delay. Extensive experiments have been performed to investigate the performance characteristics of HVP when compared with the adaptive distance-based (ADB) method, the direction-based location update (DBLU) method and the basic velocity paging (BVP) method under different system settings. The results have shown that HVP gives a better performance when compared with ADB, DBLU and BVP for different call-to-mobility ratio values and update cost to paging cost ratios.

In this paper, we study the problem of temporal consistency maintenance where a certain degree of temporal inconsistency is tolerable. We propose a suite of statistical more-less (SML) approaches to tradeoff of quality of service (QoS) of temporal consistency against the number of supported transactions. We begin with a base-line algorithm, SML-BA, which provides the requested QoS of temporal consistency. We then propose SML with optimization (SML-OPT) to further improve the QoS by better utilizing the excessive CPU capacity. Finally, we enhance SML-OPT with a slack reclaiming scheme (SML-SR). The reclaimed slacks are used to process jobs whose required computation time is larger than the guaranteed computation time. Simulation experiments are conducted to compare the performance of these schemes (SML-BA, SML-OPT and SML-SR) together with the deterministic more-less and half-half schemes. Our results show that the SML schemes are effective in trading off the schedulability of transactions and the QoS guaranteed. Moreover, SML-SR performs best and offers a significant QoS improvement over SML-BA and SML-OPT.