A Metamodeling Approach for Cross-layer Optimization: A framework and Application to Voice over WiFi

in Simulation Modelling Practice and Theory (2011), 19(9), 2117-2129

Cross-layer design has been proposed to optimize the performance of networks by exploiting the interrelations among parameters and procedures at different levels of the protocol stack. This paper ... [more ▼]

Cross-layer design has been proposed to optimize the performance of networks by exploiting the interrelations among parameters and procedures at different levels of the protocol stack. This paper introduces a quantitative framework for the study of cross-layer interactions, which enables design engineers to analyze and quantify interlayer dependencies and to identify the optimal operating point of the system, by using network economic theory principles. The framework is then used for performance optimization of a single-cell Voice over WiFi (VoWiFi) system. Insights gained from the considered scenario enable us to define a novel cross-layer Call Admission Control (CAC) scheme. The multistage CAC takes into account Quality of Service (QoS) criteria, which provide satisfaction to the end user, as well as revenue criteria that maximize the possible profit of the WiFi provider. [less ▲]

Architectures and Cross-Layer Design for Cognitive Networks

in Handbook on Sensor Networks (2010)

Network evolution towards self-aware autonomous adaptive networking attempts to overcome the ine?ciency of con?guring and managing networks, which leads to performance degradation. In order to optimize ... [more ▼]

Network evolution towards self-aware autonomous adaptive networking attempts to overcome the ine?ciency of con?guring and managing networks, which leads to performance degradation. In order to optimize network operations, the introduction of self-awareness, self-management, and self-healing into the network was proposed. This created a new paradigm in networking, known as cognitive networking. This chapter describes state-of-the-art, as well as future directions in cognitive networking. Fundamental techniques for enabling cognitive properties, such as, adaptation, learning, and goal optimization processes are detailed in this text. A comparison of available research proposals leads to the design of a promising cognitive network architecture capable of incorporating cognitive network techniques. Finally, a discussion on the required properties of the cross-layer design for cognitive networks and deployment issues are speci?ed. [less ▲]

Service-Aware Retransmission Control in Cellular Networks

in Journal of Computer Systems, Networks, and Communications (2010)

This paper proposes a service-aware cross-layer approach between application/transport layers on the mobile terminal and link layer on the wireless base station to enable dynamic control on the level of ... [more ▼]

This paper proposes a service-aware cross-layer approach between application/transport layers on the mobile terminal and link layer on the wireless base station to enable dynamic control on the level of per-packet error protection for multimedia data streams. Specifically, in the context of cellular networks, the proposed scheme enables the mobile terminal to specify to the base station the desired level of Hybrid ARQ (HARQ) protection by using an in-band control feedback channel. Such protection is dynamically adapted on a per-packet basis and depends on the perceptual importance of different packets as well as on the reception history of the flow. Experimental results demonstrate the potential benefits deriving from the proposed strategy either for audio and video real-time streams as well as for TCP-based data transfers. [less ▲]

Packet Concatenation at the IP Level for Performance Enhancement in Wireless Local Area Networks

in Wireless Networks (2008), 14(4), 519-529

Wireless local area networks experience performance degradation in presence of small packets. The main reason for that is the large overhead added at the physical and link layers. This paper proposes a ... [more ▼]

Wireless local area networks experience performance degradation in presence of small packets. The main reason for that is the large overhead added at the physical and link layers. This paper proposes a concatenation algorithm which groups IP layer packets prior to transmission, called PAC-IP. As a result, the overhead added at the physical and the link layers is shared among the grouped packets. Along with performance improvement, PAC-IP enables packet-based fairness in medium access as well as includes QoS support module handling delay-sensitive traffic demands. The performance of the proposed algorithm is evaluated through both simulations and an experimental WLAN testbed environment covering the single-hop and the widespread infrastructure network scenarios. Obtained results underline significant performance enhancement in different operating scenarios and channel conditions. [less ▲]

Logarithmic Window Increase for TCP Westwood+ for Improvement in High Speed, Long Distance Networks

in Computer Networks (2008), 52(12), 2395-2410

The majority of current Internet applications uses Transmission Control Protocol (TCP) for ensuring reliable end-to-end delivery of data over IP networks. The resulting path is, generally speaking ... [more ▼]

The majority of current Internet applications uses Transmission Control Protocol (TCP) for ensuring reliable end-to-end delivery of data over IP networks. The resulting path is, generally speaking, characterized by fairly large propagation delays (of the order of tens to hundreds of milliseconds) and increasing available bandwidth. Current TCP performance is far from representing an optimal solution in such operating conditions. The main reason lies in the conservative congestion control strategy employed, which does not let TCP to exploit the always increasing available path capacity. As a consequence, TCP optimization has been an active research topic in the research community over the last 25 years, boosted in the last few years by the widespread adoption of high-speed optical fiber links in the backbone and the emergence of supercomputing networked applications from one side and tremendous growth of wireless bandwidth in network access from another. This has led to the introduction of several alternative proposals for performing congestion control. Most of them focus on the effectiveness of bandwidth utilization, introducing more ‘‘aggressive” congestion control strategies. However, such approaches result often in unfairness among flows with substantially different RTTs, or do not present the inter-protocol fairness features required for incremental network deployment. In this paper, we propose TCP LogWestwood+, a TCP Westwood+ enhancement based on a logarithmic increase function, targeting adaptation to the high-speed wireless environment. The algorithm shows low sensitivity with respect to RTT value, while maintaining high network utilization in a wide range of network settings. The performance, fairness and stability properties of the proposed TCP LogWestwood+ are studied analytically, and then validated by means of an extensive set of experiments including computer simulations and wide area Internet measurements. [less ▲]

Enhanced GPSR Routing in Multi-Hop Vehicular Communications through Movement Awareness

in IEEE Communications Letters (2007), 11(10), 781-783

Cross-Layer Congestion Control in Ad Hoc Wireless Networks

in Ad Hoc Networks (2006), 4(6), 678-708

DAWL: A Delayed-ACK Scheme for MAC-Level Performance Enhancement of Wireless LANs

in Mobile Networks and Applications (2005), 10(5), 607-615