Abstract-The new standard IEEE 802.11e is specified to support quality-of-service in wireless local area networks. A comprehensive study of the performance of enhanced distributed channel access (EDCA), the fundamental medium access control mechanism in IEEE 802.11e, is reported in this paper. We
The default caching scheme in CCN results in a high redundancy along the symmetric request-response path, and makes the caching system ine cient. Since it was first proposed, much work has been done to improve the general caching performance of CCN. Most new caching schemes attempt to reduce the on-path redundancy by passing information on content redundancy and popularity between nodes. In this paper, we tackle the problem from a di↵erent perspective. Instead of curbing the redundancy through special caching decisions in the beginning, we take an orthogonal approach by pro-actively eliminating redundancy via an independent intra-AS procedure. We propose an intra-AS cache cooperation scheme, to e↵ectively control the redundancy level within the AS and allow neighbour nodes in an AS to collaborate in serving each other's requests. We show via trace-driven simulation, that intra-AS cache cooperation improves the system caching performance and reduces considerably the tra c load on the AS gateway links, which is very appealing from an ISP's perspective.
Despite the dramatic improvements achieved in building energy-efficient electronic devices, the amount of electricity consumed worldwide to power the global information technology infrastructure has grown tremendously in the past decade. In this paper, we propose algorithms to reduce energy consumption by data centers by considering the placement of virtual machines onto the servers in the data center intelligently. We formulate this problem as an integer programming problem, prove it is NP-hard, then explore two greedy approximation algorithms, minimum energy virtual machine (VM) scheduling algorithm (MinES) and minimum communication virtual machine scheduling algorithm (MinCS), to reduce the energy while satisfying the tenants' service level agreements. We examine the performance of these two algorithms in both small and large clusters using real data traces and synthetic workloads, and compare them to other alternatives. Our results demonstrate that MinES and MinCS yield scheduling that are within 4.3% to 6.1% energy consumption of the optimal solution while being computationally efficient.
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