In-vehicle wireless sensor/actuator networks are subject to QoS requirements for real-time performance. We show how these requirements can be met, especially for randomly distributed traffic, by our improvements of th...
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ISBN:
(纸本)9781479980925
In-vehicle wireless sensor/actuator networks are subject to QoS requirements for real-time performance. We show how these requirements can be met, especially for randomly distributed traffic, by our improvements of the Soft Real-Time Shared Time Slot (SRTST) MAC protocol. The improvements target the upper delay limit of prioritized messages and achieve a bounded delay within the delay requirements for such messages. We performed simulations with the discrete event simulator omnet++ of our improvements and compared them to the original MAC protocol.
覆盖网(Overlay)虚拟化能有效分离网络应用服务与底层网络基础设施,提升服务质量和用户体验,设计了一种利用多目标优化(multi-objective optimization,简称MOO)的通用覆盖网(general service overlay network,简称GSON)网拓扑构建算法(M...
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覆盖网(Overlay)虚拟化能有效分离网络应用服务与底层网络基础设施,提升服务质量和用户体验,设计了一种利用多目标优化(multi-objective optimization,简称MOO)的通用覆盖网(general service overlay network,简称GSON)网拓扑构建算法(MOO-GSON)。该算法利用多目标优化模型提出了以服务节点和物理链路重用为约束,从而提高了虚拟拓扑与物理网络匹配度,最小化虚拟链路代价。降低了网络总体开销。采用随机网络拓扑进行试验仿真的结果表明,在满足各类约束的条件下,本算法能有效地优化时间和成本。
The mobile technology 4G, known as Long Term Evolution (LTE), offers very high peak data, but, since it was designed specifically for data traffic, voice support is absent. So one problematic aspect is providing voice...
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ISBN:
(纸本)9781479923854
The mobile technology 4G, known as Long Term Evolution (LTE), offers very high peak data, but, since it was designed specifically for data traffic, voice support is absent. So one problematic aspect is providing voice support or having voice continuity when the user moves out of LTE coverage. The most feasible solutions are CS fallback, Voice over LTE via Generic Access (VoLGA), Single Radio Voice Call Continuity (SRVCC) and third party voice service like Skype. These solutions are discussed and compared. There are also suggested the best options for providing voice over LTE, depending on the different types of network that an operator has already deployed. Since 2 out of 4 solutions described in this paper interact with IMS, in order to demonstrate the concepts, we have designed a testing configuration, based on our own-developed LTE network simulator, 4GSim and OpenIMS Core.
A direct sensor to actuator communication model for Ethernet-based Networked Control Systems (NCSs) is presented in this paper. This model is compared to a previously introduced model including an in-loop controller n...
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ISBN:
(纸本)9781479929542
A direct sensor to actuator communication model for Ethernet-based Networked Control Systems (NCSs) is presented in this paper. This model is compared to a previously introduced model including an in-loop controller node. omnet simulations showed the success of the presented model in meeting system delay and strict zero packet loss (with no over-delayed packets) requirements. The model also showed a reduction in the end-to-end delay of control packets from sensor nodes to actuator nodes in both Fast and Gigabit switched Ethernet-Based. A major improvement is the increase in the amount of additional load the proposed model can accommodate.
Demand for videos delivered through Internet increased rapidly in recent years. In order to reduce the workload for origin server and to increase the reliability of video delivered, a dedicated content delivery networ...
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ISBN:
(纸本)9781467355803;9781467355780
Demand for videos delivered through Internet increased rapidly in recent years. In order to reduce the workload for origin server and to increase the reliability of video delivered, a dedicated content delivery network (CDN) is needed. CDN, these days, could provide a reliable network to deliver videos, often representing the origin server, to serve clients' request. Request routing peering system usually are able to route clients' request to an "appropriate" server, named as surrogate server, within a CDN. However, due to the cost involved for setting up new surrogate server, as the number of client increases, herewith, peering of CDN is being introduced to increase the capacity and the coverage, i.e. collaborating with several CDN. Our idea is to re-route a request to other CDNs when the request for a video in a particular CDN could not be found. In this paper, we also analyze the performance of such request routing system which is based on two policies, namely;(1) closest surrogate server, and (2) workload balance, in order to re-route requests to a "suitable" surrogate server, thus, providing a stably high throughput with low error rate when delivering videos to clients. The simulation results show that closest surrogate server policy performed better during non-peak hour while workload balance policy performed better during peak hour.
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