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Fractional frequency reuse (FFR), using different frequency reuse factors for cell center and edge regions, is able to effectively improve spectrum efficiency in multi-cell OFDMA networks. However, optimal performance is hard to achieve in practice as the efficiency of resource allocation could drop drastically due to the constraint from the frequency(More)
As mobile stations (MSs) in the next generation cellular wireless systems will more frequently operate on multiple applications, such as web browsing, VoIP, online video etc., energy saving becomes more critical and face new challenges from the quality of service (QoS) requirements. A special operation state, called sleep mode, is designed for energy saving(More)
This work investigates the performance of parallel R-tree where the spatial data are high dimensional objects. Due to the large number of bounding values for each bounding box in the R-tree, one disk page might contain one bounding box only. Parallel Binary R-tree(PBR-tree) is proposed to facilitate the costly node access. An analytical performance(More)
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