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

in Simulation Modelling Practice & 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 ▲]

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 ▲]

Introduction: Why Cross-Layer? Its Advantages and Disadvantages

in Cross Layer Designs in WLAN Systems (2010)

GreenCloud: A Packet-level Simulator of Energy-aware Cloud Computing Data Centers

in IEEE Global Communications Conference (GLOBECOM), Miami, FL, USA, 2009 (2009)

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

Performance Improvement in Wireless Networks using Cross-layer ARQ

in Computer Networks (2007), 51(15), 4396-4411

This paper presents a novel cross-layer approach (LLE-TCP) designed for performance enhancement of TCP over a large variety of wireless networks. LLE-TCP avoids TCP ACK packet transmission over the ... [more ▼]

This paper presents a novel cross-layer approach (LLE-TCP) designed for performance enhancement of TCP over a large variety of wireless networks. LLE-TCP avoids TCP ACK packet transmission over the wireless channel. As a result, the saved time can be utilized by the nodes for data packet delivery. The proposed scheme enhances the protocol stacks of the wireless sender (or a base station) and the receiver with cross-layer ARQ agents which support ACK suppression. ARQ agent suppresses the outgoing ACKs at the receiver side and generates them locally at the sender or base station. The performance evaluation of the proposed approach is performed via simulations as well as IEEE 802.11 testbed experiments for single-hop and infrastructure network scenarios. LLE-TCP demonstrates the performance improvement in the range of 20–100% depending on the transmitted TCP/IP datagram size. Among the factors contributing to performance enhancement are: medium busy time reduction, reduced sensibility to link errors, reduced round trip time (RTT), and improved congestion control. A good level of throughput fairness as well as a fair coexistence with state-of-the-art TCP modifications ensures proper functionality of the proposed approach, while performance advantages extended even on non-LLE-TCP users favor an incremental deployment of the technique in existing networks. [less ▲]

Cross-Layering for Performance Improvement in Multi-Hop Wireless Networks

in Journal of Interconnection Networks (2006), 7(1), 51-61