SUMMARYThe next generation broadband wireless networks deploy orthogonal frequency division multiple access (OFDMA) as the enabling technologies for broadband data transmission with QoS capabilities. In such broadband wireless systems, one major issue is how to utilize radio resource efficiently while maintaining fairness between sessions as well as providing adequate QoS. In this work, we propose an approach for OFDMA/time division duplex (TDD) downlink suitable for IEEE802.16e WiMAX systems that combines scheduling and burst mapping algorithms for a trade-off between session fairness, QoS, and spectral efficiency. While optimizing radio resources under QoS and fairness constraints is an NP-hard problem, we follow a heuristic approach that simplifies the complexity of the algorithm. Performance results show that while the new scheme outperforms the Proportional Fair algorithm in terms of fairness, it also improves the overall system spectral efficiency.
ICT is currently responsible for 4% of the EU's carbon emission. In this industry, data centers are growing quickly to supply the escalating services and application demands. The design of high performance and energy-efficient data center networks is an important issue while still being confronted with many challenges such as scalability, reliability, etc. On the other hand, the network devices' difference in power consumption as well as property make the researching process more difficult to construct a routing algorithm that effectively works with various devices. This paper presents a novel energysaving scheme that can flexibly control and route traffic relying on the difference of network devices' energy-profile. By using OpenFlow mechanism and Net-FPGA cards based on Software Defined Networks, we successfully deploy energy-aware data center network, and its experimental results show that the novel scheme improves the power saving level and energyefficiently works based on the switches' energy-profile.
In this paper we firstly proved that Mobile IP protocols are designed for mobility but not for session continuity. In contradiction, mSCTP (mobile Stream Control Transmission Protocol) appears to be the best protocol with regard to session continuity support, however it does not support location management mechanisms, thus context-aware QoS as well as other mechanisms based on knowledge of location are hardly accommodated. On the other hand, the standardized IP Multimedia Subsystem (IMS) solution initially introduced by 3GPP adopts the policy-based QoS model to map user's subscription to a pre-defined QoS level, to apply service-based charging and to prevent Theft-of-Service. In this article we propose a new approach that integrates mSCTP into IMS networks to facilitate session continuity and to provide mechanisms for service control. It is realized by a proxy based on mSCTP (mobile Stream Control Transmission Protocol) that acts as an anchor point for soft vertical handover of mobile nodes, which have multiple physical interfaces (e.g., WLAN/UMTS). The mSCTP-based proxy also supports QoS provisioning and adaptation for the mobile nodes when moving in a heterogeneous wireless environment. Results show that the signaling cost for handover in our approach can be up to 23 times smaller than that in the conventional approach.
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