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We present Duo-MAC, an asynchronous cascading wake-up scheduled MAC protocol for heterogeneous traffic forwarding in low-power wireless networks. Duo-MAC deals with energy-delay minimization problem and copes with transmission latency encountered by Today's duty-cycled protocols when forwarding heterogeneous traffic types. It switches, according to the energy and delay requirements, between Low Duty...
Handover events are a source of instability in a mobile environment, but they are unavoidable. In particular, a significant cause of quality degradation is handovers to congested access points. These cause packet drops, longer RTT, and less available bandwidth for the flow being handed over. Such performance degradation may not be acceptable with respect to the transport protocols. Through simulations,...
Wireless Networks have evolved as promising technology for numerous applications to provide Internet access to fixed and mobile wireless devices. Multicasting plays a crucial role in many applications of Wireless Networks. Several routing protocols have been proposed for multicast communication in mobile wireless networks. In this paper we propose a reactive and receiver initiated multicast routing...
The MAC protocol is important, especially for wireless LAN because of limited bandwidth. A great deal of research has been carried out and some of proposed schemes are effective. Specifically, considerable effort has been devoted to improving the IEEE 802.11 standard which is utilized widely. Previous theoretical analysis gave the upper bound of IEEE 802.11 DCF throughput which is far below the channel...
Today, communications technology is one of the most essential roles for our life. People had used many ways of transmissions such as internet, mobile phone and so on. Moreover, VoIP (Voice over Internet Protocol) is also a communications technology. In this paper, we focus on VoIP which transmits voice over packet switched networks such as LANs (Local Area Networks) or WANs (Wide Area Networks). Adding...
We propose and analyze two strategies to provide different levels of quality of service (QoS) to the DVB-SH standard. An extension of the interleaving scheme is investigated to support low latency service requirements for interactive services based on short messages. The first approach is a straightforward extension of the DVB-SH interleaver scheme based on an early-uniform interleaver profile, and...
With its new features such as multi-homing and multi-streaming the Stream Control Transmission Protocol (SCTP) has become a promising candidate as a general-purpose transport layer protocol. Multi-homing in an SCTP association can make concurrent multi-path transfer an appealing candidate to satisfy the ever increasing user demands for bandwidth. Multiple streams provide an aggregation mechanism to...
Voice over Internet Protocol is a growing technology that enables voice communication through the Internet. The transmission of audio data over packet switched networks faces lot of difficulties by a variety of network impairments. Such networks are not designed to support real time voice communication because of their variable characteristics. The conversational quality of a VoIP communication is...
Multicast services are used in emerging multimedia applications based on Quality of Service (QoS) development of multimedia group application and the construction of multicast routing tree is significant. Upper bound on the delay between sender and receiver is one of the common QoS constraints. Delay-constrained routing protocols are used to find paths subject to the delay constraint while efficiently...
Wireless ad hoc networks are a collection of mobile nodes spreading over a defined geographical area, enabling realtime collaborative applications such as push-to-talk and VoIP. Unfortunately, wireless ad hoc networks suffer from limited bandwidth and QoS constraints. A proposed eXplicit MultiCAST (XCAST) based routing protocol (P-XCAST) is presented in this paper to support team-based communications...
Multipath streaming protocols have recently attracted much attention because they provide an effective means to provide high-quality streaming over the Internet. However, many existing schemes require a long start-up delay and thus are not suitable for interactive applications such as video conferencing and tele-presence. In this paper, we focus on real-time live streaming applications with stringent...
New emerging technologies like Multimedia applications require timely delivery of information as compared to reliability. The most widely used protocols over transport layer are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). Both of these have some drawbacks while using in real time applications. TCP increases delay in transfer of data but achieving reliable transfer of data...
Due to its bandwidth efficiency, multicast makes a group-centric communication more viable in wireless ad hoc networks with limited radio resources. PIM-SM, a de facto standard multicast protocol known for its high scalability, is a good fit for a large-scale ad hoc network. However, it does not provide a robust multicast communication under RP outage and host mobility. In this paper, we propose a...
A prioritized medium access control (PMAC) protocol is proposed for wireless sensor networks, based on a binary count down approach. PMAC effectively eliminates data collision and optimizes channel allocation. Moreover, as many networks nowadays compose traffic with several priorities, the simple yet effective design of PMAC offers strict service differentiation for prioritized packets. In this paper,...
Nowadays WiMax is becoming one of the main standards for the next generation wireless transmission systems. It provides QoS mechanism, but it needs performance optimization and evaluation and it is very difficult to make coverage prediction. This paper is about QoS estimation methods and measurements over WiMax networks. It presents first performance measurements about achievable rates for data or...
Bandwidth reservation in mobile wireless networks is a very challenging task due to the instability of radio channels, node mobility and lack of coordination between mobile nodes. Previously proposed reservation MAC protocols reserve a slot to each real-time source assuming that the source will use the reserved slot in each super-frame. Since different applications may have different bandwidth requirements,...
In this paper we investigate whether scheduling packets based on path information can improve the fairness in an ad hoc network. The users may have a need for a predictable service over time and common to the whole ad hoc network. However, the performance depends on the path between sender and receiver, and it will therefore vary over time. Two schemes are analyzed; the first scheme differentiates...
Video transmission is becoming an increasingly essential part of the current Internet; however before the high video quality at the client side becomes a reality, the best effort model has to adapt the video characteristic to the network conditions. In this paper, we are proposing a media middleware component that can be added to the edge routers in DiffServ network in order to have the responsibility...
High speed downlink packet access (HSDPA) was introduced to UMTS radio access segment to provide higher capacity for new packet switched services. As a result, packet switched sessions with multiple diverse traffic flows such as concurrent voice and data, or video and data being transmitted to the same user are a likely commonplace cellular packet data scenario. In HSDPA, radio access network (RAN)...
In this paper, we study a mechanism which allows the sender application to mark video packets based on its importance in reconstructing the video. Passing such video frames to differentiated service (DiffServ) network increases the video quality and treats the video frames based on their priorities. A media aware sub-layer has been added to the edge routers in DiffServ network. The media aware sub-layer...
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