1118388
HRPD-A downlink voice/IP and data throughput and delay analysis
HRPD-A adds new forward and reverse link rates and a forward link multi-user packet capability at the MAC layer. Completed simulations reveal the performance characteristics of this system in the 1.9 GHz frequency band. These characteristics consist of capacities of voice/IP traffic and mixed data and voice/IP traffic. Downlink data traffic models consist of FTP, HTTP (Web browsing), WAP, and video streaming models. The simulation assumptions include the ITU channel models and 3GPP2 data traffic models
10478649
WiMAX Overview and System Performance
In this paper, the performance of WiMax network with DL SIMO, DL MIMO and UL SIMO is analyzed via system simulations. Two data traffic models are considered, namely Web browsing (HTTP) and full buffer sessions, operating in multi path fading channels such as the ITU pedestrian-B and vehicular-A channels. The control channel coverage and reliability of WiMAX using realistic overhead is also analyzed in this paper.
60952010
DIET — A Scalable, Robust and Adaptable Multi-Agent Platform for Information Management
The complexity of the global information infrastructure demands new approaches to managing distributed information. The Decentralised Information Ecosystem Technologies (DIET) project has produced a software platform based on a lightweight, scalable, multi-agent system that can be used to support a variety of information management applications that deal with some of this complexity. This paper describes the main components of the DIET software platform, and several examples of its application. It also considers the diversity of potential applications for this technology.
15143128
Multi-channel spectrum-agile MAC protocol with adaptive load control
Spectrum-agile radios, also known as cognitive radios, have a great potential to improve spectrum utilization by enabling dynamic access to the spectrum. A key challenge in operating these radios is how to implement an efficient medium access control (MAC) mechanism that adaptively and efficiently allocates transmission powers and spectrum according to the surrounding environment. In this work, we propose a distributed MAC protocol for operating spectrum-agile radios in a multihop ad hoc network. Our protocol differs from previous designs in that it exploits the “dual-receive” capability of radios, thus overcoming various channel access problems that are common to multi-channel designs. We conduct theoretical analysis of the protocol, and study its performance via simulations. We show significant improvement in the system throughput under the proposed MAC design. To maximize this throughput, we propose a cross-layer framework for joint adaptive load and medium access controls. In this framework, the loads of individual nodes are adapted based on the values of local MAC parameters. Simulation results show that the proposed scheme achieves more than 90% of the maximum (global) system throughput that is achieved at saturation, while guaranteeing low collision rates.
6286725
GMAC: A Game-theoretic MAC Protocol for Mobile Ad Hoc Networks
The conservative nature of the 802.11 ad hoc scheme has instigated extensive research whose goal is to improve the spatial reuse and/or energy consumption of this scheme. Transmission power control (TPC) was shown to be effective in achieving this goal. Despite their demonstrated performance gains, previously proposed power-controlled channel access protocols often incur extra hardware cost (e.g., multiple transceivers). Furthermore, they do not fully exploit the potential of power control due to the heuristic nature of power allocation and “interference margin” computations. In this paper, we propose a distributed, single-channel MAC protocol (GMAC) that is inspired by game theory. In GMAC, multiple potential transmitters are first involved in an admission phase, which enables terminals to compute the transmission powers that achieve a Nash equilibrium (NE) for the given utility function. Subsequently, successful contenders can simultaneously proceed with their transmissions. Simulation results indicate that GMAC improves the network throughput over the 802.11 scheme by about 80%, and over another single-channel power-controlled MAC protocol (POWMAC) by about 40%. These gains are achieved at no extra energy cost.
39488688
Modeling of power electronics for simulation based analysis of power systems
Given the increased penetration of power electronic converters in power systems it is necessary to study their impact in the system operation. In order to achieve that goal the power converters must be appropriately modeled in simulation or analytical studies. This paper reviews the modeling requirements and characteristics of power electronic converter models for system studies. Several models of the equipment used in a ship power system are described. The use of these models in simulation based system studies is discussed in the paper. Stability analysis is used as example for that discussion. The models are grouped into categories based on their degree of detail and use. Moreover, the validity and computational requirements of those models are also discussed.
12497271
Inequivalent manifold ranking for content-based image retrieval
We propose to improve the effectiveness and scalability of graph based manifold ranking methods in image retrieval applications by emphasizing reliable images while damping the effect of noisy or irregular ones. Label information is firstly passed between most reliable data points, then propagated to less reliable ones on manifold structure. By treating these images inequivalently, undesirable effect of noisy samples is greatly reduced, thus effectiveness of manifold ranking algorithms is enhanced. Also, graph size in terms of number of nodes and edges is dramatically reduced, resulting in a great speed-up of the algorithm. Our experiment on real world image data set demonstrates the effectiveness of the proposed approach.