Guest Editorial: Selected Papers on Wireless and Mobility from IEEE INFOCOM

The three papers in this special section were originally presented at the IEEE INFOCOM 2006 conference in Barcelona. The augmented papers, which address issues in wireless networks and mobile computing, represent the high quality of research presented at the conference.     

Modeling the performance of HTTP over several transport protocols

This paper considers the interaction of HTTP with several transport protocols, including TCP, Transaction TCP, a UDP-based request-response protocol, and HTTP with persistent TCP connections. We present an analytic model for each of these protocols and use that model to evaluate network overhead carrying HTTP traffic across a variety of network characteristics. This model includes an analysis of the transient effects of TCP slow-start. We validate this model by comparing it to network packet traces measured with two protocols (HTTP and persistent HTTP) over local and wide-area networks. We show that the model is accurate within 5% of measured performance for wide-area networks, but can underestimate latency when the bandwidth is high and delay is low. We use the model to compare the connection-setup costs of these protocols, bounding the possible performance improvement. We evaluate these costs for a range of network characteristics, finding that setup optimizations are relatively unimportant for current modem, ISDN, and LAN users but can provide moderate to substantial performance improvement over high-speed WANs. We also use the model to predict performance over future network characteristics     

Report and discussion on the IEEE ComSoc TCGN Gigabit NetworkingWorkshop 1995

Presents a summary of the second Gigabit Networking Workshop. The focus of the workshop is on end-to-end (level 4) and higher issues. Topics discussed include: ATM and B-ISDN, TCP/IP over ATM, ATM role in the future Internet-based Global Information Infrastructure, traffic monitoring and middleware     

Permeability Reduction by Sediment Retention in Saturated Sand Columns

Recently, researchers in coastal engineering have paid more attention to the role of sediment (particulate organic matter adsorbed on fine solid particles, diameter range 1– $100~\upmu $ m) in considering the biodiversity of estuaries. In this study, permeability reduction of saturated sand columns by sediment retention is investigated through laboratory experiments. Water-based sediment was injected through vertical sand columns under a constant water head difference, with different flow rates, porosities of the sand columns, and the chemical properties of sediment. It was found that the permeability reduction was uniquely correlated with flow rate and sediment properties; that is, increasing flow rate or using sediment containing high amounts of organic matter causes a significant reduction in permeability. Furthermore, an approximate experimental equation is proposed to predict the retention mass of sediment. This equation can predict the retention mass with a relative error of less than 5 %. In addition, a new model is proposed to determine the permeability reduction by sediment retention. This model could predict the permeability reduction with a relative error of 10 %.     

Telecommunications issues of intelligent database management for ground processing systems in the EOS era

Future NASA Earth science missions, including the Earth Observing Systems (EOS), will generate vast amounts of data that must be processed and stored at various locations around the world. This article presents a stepwise-refinement of the Intelligent Database Management (IDM) system of the Distributed Active Archive Center (DAAC-one of seven regionally-located EOSDIS archive sites) architecture to showcase the telecommunications issues involved. This architecture is developed into a general overall design. It is shown that the current evolution of protocols is sufficient to support IDM at Gbps rates over large distances. It is also shown that the network design can accomodate o flexible data ingestion storage pipeline and a user extraction visualization engine, without interference between the two.     

Defining high-speed protocols: five challenges and an example thatsurvives the challenges

The First IEEE Gigabit Networking (GBN) Workshop defined a set of characteristics of “Interesting” high-speed applications. The GBN criteria ensure that the application addresses a significant problem, and that it actually requires a gigabit network. This paper presents five challenges that augment the GBN criteria. These challenges ask whether gigabit applications require new research into different protocols, or can be supported by existing protocols that merely run faster. It shows a class of applications, interactive distributed multimedia, namely interactive real-time World Wide Web (WWW) access, that survive the challenges. It also shows how source presenting is a way to use excess bandwidth-delay product to reduce the browser response time, and how this is one example of a truly gigabit protocol     

Measurement of Sediment Retention in a Sandy Tidal Flat Based on Pressure Drop Model

Sediment can either play an important role in subsurface environments as a food source for bacteria or deteriorate the subsurface environments by its retention. Thus, understanding sediment retention is useful for designing the management of subsurface environments. The pressure drop model derived from the Kozeny–Carman model is experimentally verified by the seepage flow in sand beds. It was found that the water head in the sand bed under steady-state flow and variations of the water head corresponding to changes in the boundary water head could be reproduced by the pressure drop model. As the porosity of the sand bed is taken into account in the pressure drop model, the sediment retention can be predicted from variations of the porosity. Experimental results showed that the water head in the sand bed varied due to sediment retention. This ensured that variances in the porosity of the sand bed could be predicted, leading to the investigation onto sediment retention. A method based on the pressure drop model is proposed to measure temporal variations of the water head in a sandy tidal flat and river water head. From field experiments, the temporal variations of the water head in the tidal flat could be predicted when the porosity of the tidal flat was used. Conversely, it is expected that sediment retention in the tidal flat can be predicted based on the variations of the porosity, if the water head in the tidal flat is observed temporally.     

Trace identification of plant substances by combining gas chromatography-mass spectrometry and direct deposition gas chromatography-Fourier transform infrared spectrometry

The advantages of combined gas chromatography-mass spectrometry and direct deposition gas chromatography-Fourier transform infrared spectrometry at the same level of sensitivity are demonstrated using an apolar capillary column. This technique was applied to allelochemicals present in minute concentrations. The identification of volatiles in green leaves and an alkaloid is described.