While attractive in principle, architecture-based self-adaptation raises a number of research and engineering challenges. First, the ability to handle wide variety systems must be addressed. Second, need reduce costs adding external control system Our rainbow framework attempts address both problems. By adopting an approach, it provides reusable infrastructure together with mechanisms for specializing that needs specific systems. The specialization let developer capabilities choose what...

Software-based systems today are increasingly expected to dynamically self-adapt accommodate resource variability, changing user needs, and system faults. Recent work uses closed-loop control based on external models monitor adapt behavior at run time. Taking this externalized approach, the Rainbow framework we have developed software architectural a running system. A key goal primary challenge of is support reuse adaptation strategies infrastructure across different systems. We show that...

The most precious resource in a computer system is no longer its processor, memory, disk, or network, but rather human attention. Aura aims to minimize distractions on user's attention, creating an environment that adapts the context and needs. specifically intended for pervasive computing environments involving wireless communication, wearable handheld computers, smart spaces. Human attention especially scarce such environments, because user often preoccupied with walking, driving, other...

The packet pair mechanism has been shown to be a reliable method measure the bottleneck link capacity on network path, but its use for measuring available bandwidth is more challenging. In this paper, we modeling, measurements, and simulations better characterize interaction between probing packets competing traffic. We first construct simple model understand how traffic changes gap single-hop network. shows that initial critical parameter when using pairs estimate bandwidth. Based insight,...

Over the past few years, wireless networking technologies have made vast forays into our daily lives. Today, one can find 802.11 hardware and other personal technology employed at homes, shopping malls, coffee shops airports. Present-day network deployments bear two important properties: they are unplanned, with most access points (APs) deployed by users in a spontaneous manner, resulting highly variable AP densities; unmanaged, since manually configuring managing is very complicated. We...

Transmission of multimedia streams imposes a minimum-bandwidth requirement on the path being used to ensure end-to-end Quality-of-Service (QoS) guarantees. While any shortest-path algorithm can be select feasible path, additional constraints that limit resource consumption and balance network load are needed achieve efficient utilization. We present systematic evaluation four routing algorithms offer different tradeoffs between limiting hop count balancing load. Our considers not only call...

Increasingly, 802.11 devices are being used by mobile users. This results in very dynamic wireless channels that difficult to use efficiently. Current rate selection algorithms dominated probe-based approaches search for the best transmission using trial-and-error. In environments, techniques often perform poorly because they inefficiently moving target presented constantly changing channel. We have developed a channel-aware adaptation algorithm CHARM - uses signal strength measurements...

There is general belief that networks based on wireless technologies have much higher error rates than those more traditional such as optical fiber, coaxial cable, or twisted pair wiring. This difference has motivated research new protocol suites specifically for networks. While the characteristics of wired been well documented, less experimental data available LANs.In this paper we report results a study characterizing environment provided by AT&T WaveLAN, commercial product designed...

Channel models for vehicular networks typically disregard the effect of vehicles as physical obstructions wireless signal. We aim to clarify validity this simplification by quantifying impact through a series experiments. Using two cars equipped with Dedicated Short Range Communications (DSRC) hardware designed use, we perform experimental measurements in order collect received signal power and packet delivery ratio information multitude relevant scenarios: parking lot, highway, suburban...

The ability to locate network bottlenecks along end-to-end paths on the Internet is of great interest both operators and researchers. For example, knowing where bottleneck links are, can apply traffic engineering either at interdomain or intradomain level improve routing. Existing tools fail identify location bottlenecks, generate a large amount probing packets. In addition, they often require access end points. this paper we present Pathneck, tool that allows users efficiently accurately...

Increased user concern over security and privacy on the Internet has led to widespread adoption of HTTPS, secure version HTTP. HTTPS authenticates communicating end points provides confidentiality for ensuing communication. However, as with any solution, it does not come free. may introduce overhead in terms infrastructure costs, communication latency, data usage, energy consumption. Moreover, given opaqueness encrypted communication, in-network value added services requiring visibility into...

Energy management is a critical issue for mobile devices, with network activity often consuming significant portion of the total system energy. In this paper, we propose Catnap, that reduces energy consumption devices by allowing them to sleep during data transfers. Catnap exploits high bandwidth wireless interfaces -- which offer significantly higher compared available across Internet combining small gaps between packets into meaningful intervals, thereby NIC as well device doze off....

Question answering (Q&A) communities have been gaining popularity in the past few years. The success of such sites depends mainly on contribution a small number expert users who provide significant portion helpful answers, and so identifying that potential becoming strong contributers is an important task for owners communities.

Motivated by limitations in today's host-based IP network architecture, recent studies have proposed clean-slate architectures centered around alternative first-class principals, such as content, services, or users. However, much like the host-centric design, elevating one principal type above others hinders communication between other principals and inhibits network's capability to evolve. Our work presents eXpressive Internet Architecture (XIA), an architecture with native support for...

A significant fraction of Internet traffic is now encrypted and HTTPS will likely be the default in HTTP/2. However, Transport Layer Security (TLS), standard protocol for encryption Internet, assumes that all functionality resides at endpoints, making it impossible to use in-network services optimize network resource usage, improve user experience, protect clients servers from security threats. Re-introducing into TLS sessions today done through hacks, often weakening overall security.

Pervasive computing applications are increasingly leveraging contextual information from several sources to provide users with behavior appropriate the environment in which they reside. If these of used and deployed an ad hoc manner however may overlapping functionality, fail needed require use inconsistent interfaces by applications. To overcome problems, we introduce a service that provides via virtual database. Unlike previous efforts, our consistent, lightweight, powerful mechanism for...

We study how to improve the throughput of high-bandwidth traffic such as large file transfers in a network where resources are fairly shared among connections. While it is possible devise priority or reservation-based schemes that give preferential treatment at expense other connections, we focus on use routing algorithms resource allocation while maintaining max-min fair share semantics. In our approach, closely coupled with congestion control sense information, rates allocated existing...

The demand for wireless bandwidth in indoor environments such as homes and offices continues to increase rapidly. Although technologies MIMO can reach link throughputs of 100s Mbps (802.11n) a single link, the question how we deliver high throughput large number densely-packed devices remains an open problem. Directional antennas have been shown be effective way spatial reuse, but past work has focused largely on outdoor where interactions between links usually ignored. This assumption is...

The Internet is rapidly changing from a set of wires and switches that carry packets into sophisticated infrastructure delivers complex value-added services to end users. Services can range bit transport all the way up distributed like video teleconferencing, data mining, interactive simulations. Before such be supported in general dynamic manner we have develop appropriate resource management mechanisms. These mechanisms must make it possible identify allocate resources meet service or...

Wireless links can exhibit high error rates due to attenuation, fading, or interfering active radiation sources. To make matters worse, be highly variable changes in the wireless environment. Researchers and developers have explored a wide range of solutions optimize communication this difficult environment, including traditional end-to-end solutions, link-layer involving layer four processing inside network. A significant challenge is ensuring that systems with multiple layers control avoid...