Queue Management Mechanism for 802.11 Base Stations

in IEEE Communications Letters (2011), 15(7), 728-730

This paper presents a novel queue management mechanism for base stations in infrastructure IEEE 802.11 networks. The mechanism is transparent to high-level protocols and is compatible with the standard ... [more ▼]

This paper presents a novel queue management mechanism for base stations in infrastructure IEEE 802.11 networks. The mechanism is transparent to high-level protocols and is compatible with the standard. Its effectiveness is illustrated by showing that it can ameliorate the RTT unfairness and the MAC anomaly problems in wired-cum-wireless networks. [less ▲]

DENS: Data Center Energy-Efficient Network-Aware Scheduling

in IEEE/ACM International Conference on Green Computing and Communications (GreenCom), Hangzhou, China, 2010 (2010)

In modern data centers, energy consumption accounts for a considerably large slice of operational expenses. The state of the art in data center energy optimization is focusing only on job distribution ... [more ▼]

In modern data centers, energy consumption accounts for a considerably large slice of operational expenses. The state of the art in data center energy optimization is focusing only on job distribution between computing servers based on workload or thermal profiles. This paper underlines the role of communication fabric in data center energy consumption and presents a scheduling approach that combines energy efficiency and network awareness, termed DENS. The DENS methodology balances the energy consumption of a data center, individual job performance, and traffic demands. The proposed approach optimizes the tradeoff between job consolidation (to minimize the amount of computing servers) and distribution of traffic patterns (to avoid hotspots in the data center network). [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 ▲]

Formal Methods in Cross Layer Modeling and Optimization of Wireless Networks: State of the Art and Future Directions

in Heterogeneous Next Generation Networking: Innovations and Platforms (2008)

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 ▲]

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-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 & Applications (2005), 10(5), 607-615