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Because wireless channel condition is time-varying, the allocated bandwidth is usually not fixed. Therefore, it is a challenge to guarantee QoS, especially for bandwidth- consuming and delay-sensitive multimedia applications. In this paper, we propose a cross-layer mechanism to improve the quality of H.264 video when encountering short-term bandwidth fluctuations over IEEE 802.11e wireless networks...
With the advance of various wireless access technologies, the demand for a mobile user equipped with multiple air interfaces simultaneously executing diverse applications emerged. In such network environment, per- application mobility management is a key to allow each application of an end user device to dynamically and fully take advantage of the most suitable access technology. In this paper, we...
4G supports various types of services. The coverage of high-speed data service is smaller than that of low-speed data service, which make the high-speed data service users occur dropping before reaching the handover area. In order to solve the problem, this paper proposes A Coverage-based Handover Algorithm for High-speed Data Service (CBH), which extends the coverage of high-speed data service by...
A throughput-maximization call admission control (CAC) policy is proposed for CDMA beamforming systems in which the QoS requirements in both physical and network layers can be guaranteed. While the existing cross-layer CAC policies rely on a separate reduced-outage-probability (ROP) algorithm to guarantee the physical layer QoS requirement, which adds to system complexity and reduces spectral efficiency,...
Coverage and connectivity are both attractive issues in wireless sensor networks. Both of them are important measurements of quality of service (Qos). Coverage configuration is an effective method to alleviate the energy-limitation problem of sensor nodes, while network connectivity is an unelectable problem guaranteeing the network usefulness. Existing researches promoted many protocols to configure...
We consider a cross-layer scheme for the downlink multiuser Orthogonal Frequency Division Multiple Access (OFDMA) for mobile WiMAX (Worldwide Interoperability for Microwave Access) based on IEEE802.16e. We propose an intelligent Medium Access Control (MAC) that adapts with physical layer in response to the different QoS requirements of the service flows in the system. Our scheme satisfies the maximum...
This paper considers decentralized cross-layer optimization for multichannel random access with partial-local knowledge. In the network scenario considered, users are not necessarily within the transmission ranges of all other users, and each user may choose to send packets to or receive packets from different users simultaneously. A criterion for cross-layer optimization is provided leading to a...
Diversity-embedded space-time block coding (DE- STBC) introduced in [1] is a class of non-orthogonal STBC which can provide multiple diversity orders and transmission rates for the information symbols. This is achieved by transmitting the information symbols in layers each characterized by a diversity-rate tuple according to its QoS requirement. This paper derives a closed-form performance bound for...
In 4G networks, various wireless access technologies will be integrated into a heterogeneous network based on an IP core network infrastructure. Thus, numerous works focus on mobility and vertical handover management to allow multiple-interfaces mobile terminals to roam seamlessly between these access networks. The different handoff schemes can be classified into three approaches according to where...
IEEE 802.16, known as WiMAX, has received much attention for its capability to support multiple types of applications with diverse QoS requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue. In this paper, we propose a hierarchical downlink resource management framework for OFDMA based WiMAX systems. Our framework consists of a dynamic resource...
Significant throughput gains can be obtained in multi-user wireless system by exploiting the combination of multi-user scheduling in media access control (MAC) layer and MIMO spatial multiplexing using precoding in physical (PHY) layer. In this paper, we propose a multi-stage hybrid scheduling scheme for codebook-based precoding system, which applies different scheduling methods at different scheduling...
IEEE 802.11 is now being used in many situations where access point (AP) power saving would be highly desirable. Unfortunately, this is not possible since the existing standard requires that APs remain active at all times. In this paper, we present a framework for a power saving quality-of-service (QoS) enabled access point (PSQAP), intended for use in low power infrastructure applications. The proposed...
The IEEE 802.11-based wireless local area networks (WLANs) are widely used for high-speed wireless data access. With the recent 802.11e quality-of-service (QoS) extension, realtime applications such as voice over IP and video streaming are finding their way to be running over WLANs. The recent 802.11n proposal aims to provide higher throughput support for bandwidth-intensive multimedia applications...
In this paper, we propose a novel and efficient OFDMA radio resource management approach based on standard Linear Programming theory. Our approach overcomes the drawbacks of previously proposed algorithms by considering multiple service scenarios, multiple quality of service (QoS) parameters and use of multiple time slots per frame. Further, the algorithm has a considerably low complexity and is shown...
Adaptive transmission which adjusts optimally transmit power level, preceding matrix, modulation and coding schemes at the cost of perfect channel state information (CSI) , can greatly improve the performance of a communication link under fading environment. As the perfect CSI is difficult to be available at transmitter, it is valuable to study the adaptive design with partial CSI. Previous works...
A utility based resource allocation scheme is investigated for improving system performance of 802.16 OFDMA systems supporting a mix of multi-media traffic types. We show that a utility based approach can improve system capacity over conventional proportional-fair resource allocation schemes through more efficient allocation of only the required resources demanded by the QoS profile of each traffic...
Existing terminal oriented handover mechanisms capable of meeting the strict delay bounds of real time applications such as VoIP do not consider the QoS of candidate handover networks. In this paper ECHO - a QoS based handover solution for VoIP- is proposed. ECHO is endpoint centric and does not require any network support; it leverages the SCTP transport protocol. ECHO incorporates network metrics...
This paper investigates the construction of a multicast tree satisfying Quality of Service (QoS) real-time group communication in a heterogeneous network comprising multiple Mobile Ad-hoc NETworks (MANETs) attached to the backbone Internet. The main objective of our work is to optimize the Delay- and delay Variation Bounded Multicast Tree (DVBMT) problem, which has been proved to be NP-complete. This...
The use of 802.11-based multi-hop wireless mesh networks for Internet access is extensive and growing. The primary advantages of this approach are ease of deployment and lower cost. However, these networks are designed for web and e-mail applications. Highly interactive applications, such as multiplayer online games and VoIP, with their requirements for low delay, present significant challenges to...
Streaming and multimedia services are key applications in UWB-based high-rate short-range wireless personal area networks (WPANs). In this paper, we study how to support the quality of service (QoS) requirement of these services over the distributed TDMA-based WiMedia UWB MAC protocol. We develop an integer-linear programming model to solve the path available bandwidth problem. To reduce the computation...
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