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The existing IEEE 802.16 is a series of Wireless Broadband standards known as WiMAX as an important technology for providing high-speed Internet access to home and business subscribers in a wide area cellular network. It has defined real time and non-real time services. But the standard does not specify transmission scheduling schemes to support the services. In order to support the delay sensitive...
This paper describes the scheduling framework for a new operating system called "Quest". The three main goals of Quest are to ensure safety, predictability and efficiency of software execution. For this paper, we focus on one aspect of predictability, involving the integrated management of tasks and I/O events such as interrupts. Quest's scheduling infrastructure is based around the concept...
The hierarchical real-time scheduling framework is a widely accepted model to facilitate the design and analysis of the increasingly complex real-time systems. Interface abstraction and composition are the key issues in the hierarchical scheduling framework analysis. Schedulability is essential to guarantee that the timing requirements of all components are satisfied. In order for the design to be...
In this paper, we propose two adaptive scheduling approaches to support real-time control applications with highly varying computation times. The use of a resource reservation scheduler enables the construction of a dynamic model describing the evolution of the computing delays, which can be incorporated in the system closed loop dynamics. The two approaches differ for the assumptions on the sequence...
We present an algorithm for bandwidth allocation for delay-sensitive traffic in multi-hop wireless sensor networks. Our solution considers both periodic as well as aperiodic real-time traffic in an unified manner. We also present a distributed MAC protocol that conforms to the bandwidth allocation and thus satisfies the latency requirements of realtime traffic. Additionally, the protocol provides...
Usually thousands of avatars are simultaneously online in P2P MMOG. To keep game's real-time, MMOG adopts some packet aggregation mechanisms in P2P network. This paper proposes a packet aggregation mechanism for Massive Multiplayer Online Game (MMOG) in P2P, which aggregates game packets into a single packet based on game interactivity threshold and aggregation threshold. The number of transmissions...
In this paper we present a new admission control (AC) for IEEE 802.16. The AC aims to accept new connections according to the negotiated service class (UGS, rtPS, nrTPS, and BE). To achieve this goal we propose to use the token bucket concept that provide QoS for real time traffics without degrading the QoS of non real time traffic. To show the benefit of the proposed AC, an analytical model based...
Service-oriented architectures (SOA) provide application systems the flexibility and cost-savings of dynamically composing workflows from reusable services. However, current SOA frameworks do not provide support for real-time workflow planning and execution. The goal of the RT-Llama SOA middleware framework is to address these new requirements. It works both at the service-level, by enhancing existing...
WiMAX is one of the most familiar broadband wireless access technologies that support multimedia transmission. IEEE802.16 Medium Access Control (MAC) covers a large area for bandwidth allocation and QoS mechanisms for various types of applications. Nevertheless, the standard lacks a MAC scheduling algorithm that has a multi-dimensional objective of satisfying QoS requirements of the users, maximizing...
DCCP is proposed to replace UDP for its ability of congestion control while maintaining its promptness by ignoring lost packets as UDP does. The network would suffer less congestion. However, whether the applications that switch from UDP to DCCP can maintain their needed performance or not is a big question. This paper investigates this problem by evaluating DCCP based VoIP vs. a variety of TCPs using...
This paper proposes a learning approach to solve adaptive Connection Admission Control (CAC) schemes in future wireless networks. Real time connections (that require lower delay bounds than non-real-time) are subdivided into hard realtime (requiring constant bandwidth capacity) or adaptive (that have flexible bandwidth requirements). The CAC for such a mix of traffic types is a complex constraint...
One of the most popular applications of IEEE 802.16 network is to serve as a backhaul service for IEEE 802.11 networks. However, the traffic of an IEEE 802.16 connection aggregated from IEEE 802.11 networks fluctuates. Thus, efficient bandwidth reservation at the subscriber station (SS) is an importance issue. This study proposes a simple and flexible bandwidth reservation scheme at the SS, called...
The Quality of Service (QoS) support of multimedia services over wireless Mobile Ad hoc Networks (MANETs) is one of the hottest challenges facing todays research community working on this area. Most existing works on QoS in ad hoc networks has been carried out under the assumption that the underlying QoS architecture is reservation based. In such architecture, mobile nodes maintain per-flow state...
The paper is about mobile Stream Control Transmission Protocol (mSCTP) and the problems related to simultaneous mobility. Simultaneous mobility is when the both endpoints of a communication session are mobile and they move at about the same time. mSCTP works well in the case of non-simultaneous mobility where the SCTP association is established between a mobile endpoint and a stationary one. In the...
Most 802.11 WirelessLAN media transport networks communicate on a shared channel. Since bandwidth- and QoS-demands of new media content constantly increase, network capacities tend to be bailed out soon, if the entire WLAN spectrum is not efficiently exploited. The proposed multi-layer approach combines dynamic channel distribution with additional dynamic interface bundling for multi-interface mesh...
In state-of-the-art multi-processor systems-on-chip (MPSoC), interconnect of processing elements has a major impact on the system's overall average-case and worst-case performance. Moreover, in real-time applications predictability of inter-chip communication latency is imperative for bounding the response time of the overall system. In shared-memory MPSoCs buses are still the prevalent means of on-chip...
This paper provides new optimal H.264 SVC video transmission method over multiple networks which have different packet drop rates. The proposed method has two steps : First, the proposed method prioritizes SVC layers and slice groups by their importance using flexible macroblock ordering (FMO). Secondly, it allocates them to the prioritized networks by packet loss rate. The experimental result shows...
In recent years, it has become imperative to teach digital communications to Electronics and Communications engineering majors. In this paper, we present a four-month undergraduate course on digital communications in which students design and implement a complete, real-time interactive communications system that transmits data in digital form between two computers. The only prerequisite is a course...
TCRTP is a multiplexing scheme for RTP, defined by IETF, which reduces the overhead of real-time flows. This work presents a preliminary study of how the number of multiplexed flows in TCRTP can affect the Quality of Service (QoS) of VoIP in terms of R-factor. Two different buffer policies are considered. The conclusion is that multiplexing all the calls in a single TCRTP flow is not always the best...
In recent consumer electronics devices, virtualization is widely adopted for diverse reasons such as enhanced reliability, stronger security and better user customizability. Recent CE virtual machines require not only diverse functionalities of GPOS, but also real-time performance of RTOS. However, the current hypervisor-based virtual machine monitors cannot sufficiently support both RTOS and GPOS...
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