Quality of Service

The IEC61499 is an open standard for distributed control and automation. The interface between control software and hardware or communications is achieved by means of the so-called Service Interface Function Blocks (SIFB). This paper presents the guidelines to build communication SIFBs based on the emerging OMG DDS (Data Distribution Service) middleware. This specification implements in a very efficient way the Publisher/Subscriber paradigm providing significant QoS configuration possibilities. These characteristics make DDS suitable for implementing the communications among time-critical devices. By using these DDS-SIFBs within IEC61499 code generation tools, the designers of the distributed applications will be allowed to use this powerful technology in the new distributed applications.

This paper seeks to provide challenges in mobile multimedia communication together with engineering perspective. It is known that advent of powerful hand-held devices and the desire for communication on the move are driving forces behind an engineering mobile technology. Quality of service (QoS) including the corresponding infrastructure presents the framework toward next-generation wireless networks. The goal is to analyze network mobility issues ad requirements in the context toward the fourth generation (4G) networks. In the first part of this article, we deal with key drivers in mobile multimedia including technologies overview. The second part gives quality of service requirements and challenges including the network infrastructure.

Cognitive radio has the ability to sense the environment and adapt its behavior to optimize communication features, such as quality of service in the presence of interference and noise. In physical layer to achieve this goal, different phases of sensing, channel estimation, and configuration selection are necessary. The sensing part measures the interference level, recognize the spectrum holes, and send this information to channel estimator. In the next step, channel state information (CSI) is used for data detection and also sent to the transmitter through a limited feedback. CSI feedback consists of achievable rate, SNR value, modulation or coding schemes (MCS). Feedback link improves the system performance in the cost of complexity and delay. In this paper, we present and compare different feedback schemes for cognitive radio and study the channel capacity when an imperfect feedback link is corrupted by noise and delay.

This experience paper summarizes the key lessons we learned throughout the design and implementation of the Aurora stream-processing engine. For the past 2 years, we have built five stream-based applications using Aurora. We first describe in detail these applications and their implementation in Aurora. We then reflect on the design of Aurora based on this experience. Finally, we discuss our initial ideas on a follow-on project, called Borealis, whose goal is to eliminate the limitations of Aurora as well as to address new key ...

This paper applies to cross traffic estimation, a new methodology for analyzing and interpreting measurement collected over Internet. This new approach is based on inferring cross traffic characteristics that lead to the observed losses by using an associated a priori constructive model.

Nowadays dynamic service management frameworks are proposed to ensure end-to-end QoS. To achieve this goal, it is necessary to manage Service Level Agreements (SLA) which specify quality parameters of the services operation such as availability and performance. ...

This paper proposes efficient resource allocation techniques for a policy-based wireless/wireline interworking architecture, where quality of service (QoS) provisioning and resource allocation is driven by the service level agreement (SLA). For end-to-end IP QoS delivery, each wireless access domain can independently choose its internal resource management policies to guarantee the customer access SLA (CASLA), while the border-crossing traffic is served by a core network following policy rules to meet the transit domain SLA (TRSLA). Particularly, we propose an engineered priority resource sharing scheme for a voice/data integrated wireless domain, where the policy rules allow cellular-only access or cellular/WLAN interworked access. By such a resource sharing scheme, the CASLA for each service class is met with efficient resource utilization, and the interdomain TRSLA bandwidth requirement can be easily determined. In the transit domain, the traffic load fluctuation from upstream access domains is tackled by an inter-TRSLA resource sharing technique, where the spare capacity from underloaded TRSLAs can be exploited by the overloaded TRSLAs to improve resource utilization. Advantages of the inter-SLA resource sharing technique are that the core network service provider can freely design the policy rules that define underload and overload status, determine the bandwidth reservation, and distribute the spare resources among bandwidth borrowers, while all the policies are supported by a common set of resource allocation techniques.

The recent advances in miniaturization and the creation of low-power circuits, combined with small-sized batteries have made the development of wireless sensor networks a working reality. Lately, the production of cheap complementary metal-oxide semiconductor cameras and microphones, which are able to capture rich multimedia content, gave birth to what is called Wireless Multimedia Sensor Networks (WMSNs). WMSNs will boost the capabilities of current wireless sensor networks, and will fuel several novel applications, like multimedia surveillance sensor networks. WMSNs introduce several new research challenges, mainly related to mechanisms to deliver application-level Quality-of-Service (e.g., latency minimization). To address this goal in an environment with extreme resource constraints, with variable channel capacity and with requirements for multimedia in-network processing, the caching of multimedia data, exploiting the cooperation among sensor nodes is vital. This article presents a cooperative caching solution particularly suitable for WMSNs. The proposed caching solution exploits sensor nodes which reside in “positions” of the network that allow them to forward packets or communicate decisions within short latency. These so-called “mediator” nodes are selected dynamically, so as to avoid the creation of hot-spots in the communication and the depletion of their energy. The mediators are not more powerful than the rest of the nodes, but they have some special role in implementing the cooperation among the sensors. The proposed cooperative caching protocol includes components for locating cached data as well as for implementing data purging out of the sensor caches. The proposed solution is evaluated extensively in an advanced simulation environment, and it is compared to the state-of-the-art cooperative caching algorithm for mobile ad hoc networks. The results confirm that the proposed caching mechanism prevails over its competitor.

In transactional systems, the objectives of quality of service regarding are often specified by Service Level Objectives (SLOs) that stipulate a response time to be achieved for a percentile of the transactions. Usually, there are different client classes with different SLOs. In this paper, we extend a technique that enforces the fulfilment of the SLOs using admission control. The admission

The power control of wireless networks is formulated using a stochastic optimal control framework, in which the evolution of the channel is described by stochastic differential equations. Under this scenario, average and probabilistic Quality of Service (QoS) measures are introduced to evaluate the performance of any control strategy, while a solution of the stochastic optimal power control is obtained through

We present the Convergence Processor, an innovative component that integrates a high performance 32- bit RISC core, a custom IP core optimised for header-processing and other blocks for specific communication interfaces required for the delivery of broadband residential applications. The component is a System-on-Chip supporting the real time processing of packets and protocol data units from various networking interfaces. Its

In multi-tenant cloud systems today, provisioning of resources for new tenancy is based on selection from a catalogue published by the cloud provider. The published images are generally a stack of appliances with Infrastructure (IaaS) and Platform (PaaS) layers and optionally Application layers (SaaS). Such a ready-made model enables quicker and streamlined resource provisioning to clients. However, this approach poses certain challenges to clients in the short run and providers in the long run. Unique tenancy requirements from each client are forcibly generalized by selecting one of the available images from the catalogue as the tenancy requirements are not modeled or validated to start with. Moreover, resource provisioning is mostly done towards addressing the peak load expectations in the tenancy. Such a static approach does not help in adapting to dynamically changing tenancy requirements, most often leading to the tenants owning and subsequently paying for more than what they n...

In satellite networks, voice over IP performance is degraded by long delays and low bandwidth. Both call setup time and quality of service (QoS) for voice calls are affected. Separate studies have been undertaken for these performance metrics. In this paper, we have carried out experiments using different voice codecs to evaluate SIP call setup time and QoS parameters together.