A tremendous amount of research has been done toward improving transport-layer performance over wireless data networks. The improved transport layer protocols are typically application-unaware. In this paper, we argue that the behavior of applications can and does dominate the actual performance experienced. More importantly, we show that for practical applications, application behavior all but completely negates any improvement achievable through better transport layer protocols. In this context, we motivate an application-aware, but application transparent, solution suite called A^3 (application-aware acceleration) that uses a set of design principles realized in an application-specific fashion to overcome the typical behavioral problems of applications. We demonstrate the performance of A^3 through both emulations using realistic application traffic traces and implementations using the NetFilter utility.

Current popular web-browsers simply fetch the entire web-page from the server in a greedy fashion. This simple web fetching mechanism employed by browsers is inappropriate for use in low-bandwidth networks, since they cause large response times for users unneccesarily. In this paper, we first analyze the reasons that cause large response times by considering several factors including the properties of typical web-pages and browsers, the interaction of the HTTP and TCP protocols, and the impact of server-side optimization techniques. We then propose three easy-to-deploy browser-side optimization mechanisms to reduce the user response time. Through simulations, we compare the performance of our solution with that of current browsers and show that the proposed scheme brings significant performance benefits in terms of user-perceived response times.

Web-based information access suffers tremendously in low-bandwidth wireless data networks due to the non-correlation between the content transferred across the wireless links and the actual data that is used to serve the user requests. As a result, the current web-access mechanisms face such problems as unnecessary bandwidth consumption, large response times, no service for partial disconnections, and low system utilization in wireless networks. In order to solve these problems with web-transfer in wireless networks, we present a new middleware for wireless web-access called Cut-Load, which performs application unaware content-partitioning in the graphical domain residing at both the mobile client and the proxy server that the mobile client communicates with. Cut-Load uses dynamic mode selection, opportunistic hoarding, transparent mode transfer, and display caching for efficient wireless web-access. Through simulations, we compare the performance of Cut-Load with that of the current web-access mechanisms and show that the proposed middleware brings significant performance benefits both in terms of bandwidth consumption and user-perceived response times.

A tremendous amount of research has been done toward improving transport layer performance over wireless data networks. The improved transport layer protocols are typically application-unaware. In this paper, we argue that the behavior of applications can and do dominate the actual performance experienced. More importantly, we show that for practical applications, application behavior all but completely negates any improvements achievable through better transport layer protocols. In this context, we motivate an application-aware, but application transparent, solution suite called A 3 (application-aware acceleration) that uses a set of design principles realized in an application specific fashion to overcome the typical behavioral problems of applications. We demonstrate the performance of A3 through emulations using realistic application traffic traces.

In this paper, we consider the problem of file synchronization when a mobile host shares files with a backbone file server in a network file system. Several diff schemes have been proposed to improve upon the transfer overheads of conventional file synchronization approaches which use full file transfer. These schemes compute the binary diff of the new file with respect to the old copy at the server and transfer the computed diff to the server for file-synchronization. However, Lee et al. have shown that the performance of diff can be significantly improved upon by shipping user operations as opposed to the data itself. Using this as motivation, we present a purely application-unaware approach called Mimic that relies on transferring raw user activity to the server for file synchronization. Through a simple prototype of the proposed approach, we show that Mimic can outperform diff under many common conditions. We also identify conditions under which diff based approaches do perform better than the proposed approach, but show that detection of such conditions is straightforward, thus enabling both schemes to be used in tandem with a mobile file system for bandwidth-efficient file synchronization.

we present a medium access control (MAC) protocol for ad hoc networks with multiple input multiple output (MIMO) links. MIMO links provide extremely high spectral efficiencies in multipath channels by simultaneously transmitting multiple independent data streams in the same channel. MAC protocols have been proposed in related work for ad hoc networks with other classes of smart antennas such as switched beam antennas. However, as we substantiate in the paper, the unique characteristics of MIMO links coupled with several key optimization considerations, necessitate an entirely new MAC protocol. We identify several advantages of MIMO links, and discuss key optimization considerations that can help in realizing an effective MAC protocol for such an environment. We present a centralized algorithm called stream-controlled medium access (SCMA) that has the key optimization considerations incorporated in its design. Finally, we present a distributed SCMA protocol that approximates the centralized algorithm and compare its performance against that of baseline protocols that are CSMA/CA variants.