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 ▲]

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 ▲]

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 ▲]

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)

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

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

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