ADSL Links Research Articles

Tele-operated ultrasound scans using a robotic probe and an ADSL or satellite link. Application to abdominal, pelvic, vascular, fetal and cardiac organs

The ratio of experienced work-related musculoskeletal discomfort among obstetric sonographers has been reported to be as high as 80–90%. Risk factors are excessive probe contact forces long reach and static positions. Robot Assisted Ultrasound has potential to reduce the risks but in order to design such solutions, a critical need exists for a deeper understanding of the related risk factors. This involves quantification of the imposed transducer contact forces during obstetric scans. Thus, the objective of this study was to provide more accurate probe-contact force information through the recording of probe contact forces during scans of 40 pregnant women. Factors addressed were operator experience, subject Body Mass Index (BMI), foetus size, gestational age and the purpose of the scan. The BMI of the pregnant women had a significant correlation with the mean and maximum contact forces. The mean and maximum axial contact forces were 9.05 N and 37.63 N, respectively. The dependency of the applied transducer contact force versus the operator experience was found significant. The study results provide design information about required contact forces for robotic solutions to the ergonomic challenges of the sonographers.

Notes from an internet chair

The ACM 8th international conference on emerging Networking EXperiements and Technologies (CoNEXT) was or- ganized in a lovely hotel in the south of France. Although it was in an excellent location in the city center of Nice with views to the sea, it suffered from poor Internet connectivity. In this paper we describe what happened to the network at CoNEXT and explain why Internet connectivity is usually a problem at small hotel venues. Next we highlight the usual issues with the network equipment that leads to the general network dissatisfaction of conference attendees. Finally we describe how we alleviated the problem by offloading network services and all network traffic into the cloud while supporting over 100 simultaneous connected devices on a single ADSL link with a device that is rated to only support around 15-20. Our experience shows that with simple offloading of certain network services, small conference venues with limited budget no longer have to be plagued by the usual factors that lead to an unsatisfactory Internet connectivity experience.

Estimating ADSL Link Capacity by Measuring RTT of Different Length Packets

This letter proposes a practical scheme that can estimate ADSL link rates. The proposed scheme allows us to estimate ADSL link rates from measurements made at the NOC using existing communications protocols and network node facilities; it imposes no heavy traffic overhead. The proposed scheme consists of two major steps. The first step is to collect measured data of round trip times (RTT) for both long and short packets to find their minimum values of RTTs by sending Internet Control Message Protocol (ICMP) echo request messages. The second step is to estimate the ADSL down- and up-link rates by using the difference in RTT between long and short packets and the experimentally-obtained correlated relationships between ADSL down- and up-link rates. RTTs are experimentally measured for an IP network, and it is shown that the down- and up-link rates can be obtained in a simple manner.

Performance Evaluation of Peer-to-Peer Progressive Download in Broadband Access Networks

P2P (Peer-to-Peer) file sharing architectures have scalable and cost-effective features. Hence, the application of P2P architectures to media streaming is attractive and expected to be an alternative to the current video streaming using IP multicast or content delivery systems because the current systems require expensive network infrastructures and large scale centralized cache storage systems. In this paper, we investigate the P2P progressive download enabling Internet video streaming services. We demonstrated the capability of the P2P progressive download in both laboratory test network as well as in the Internet. Through the experiments, we clarified the contribution of the FTTH links to the P2P progressive download in the heterogeneous access networks consisting of FTTH and ADSL links. We analyzed the cause of some download performance degradation occurred in the experiment and discussed about the effective methods to provide the video streaming service using P2P progressive download in the current heterogeneous networks.

SSL splitting: Securely serving data from untrusted caches

A popular technique for reducing the bandwidth load on Web servers is to serve the content from proxies. Typically these hosts are trusted by the clients and server not to modify the data that they proxy. SSL splitting is a new technique for guaranteeing the integrity of data served from proxies without requiring changes to Web clients. Instead of relaying an insecure HTTP connection, an SSL splitting proxy simulates a normal Secure Sockets Layer (SSL) connection with the client by merging authentication records from the server with data records from a cache. This technique reduces the bandwidth load on the server, while allowing an unmodified Web browser to verify that the data served from proxies is endorsed by the originating server. SSL splitting is implemented as a patch to the industry-standard OpenSSL library, with which the server is linked. In experiments replaying two-hour access.log traces taken from LCS Web sites over an ADSL link, SSL splitting reduces bandwidth consumption of the server by between 25% and 90% depending on the warmth of the cache and the redundancy of the trace. Uncached requests forwarded through the proxy exhibit latencies within approximately 5% of those of an unmodified SSL server.

A novel architecture for remote home automation e-services on an OSGi platform via high-speed internet connection ensuring QoS support by using RSVP technology

This paper discusses a novel architecture for remote home automation networks e-services on an OSGi platform via high speed Internet connections ensuring QoS support. These connections can be ADSL links, an emerging technology which provides the user of the local loop with broadband speeds. Since ADSL is a technology in the local loop, the presence of a signaling mechanism based on RSVP is necessary to maintain the high speed links through the network. So, a remote enduser who manages a home automation network can use an ADSL connection to assure the home automation e-services. Thus, guaranteed bandwidth as well as limited delay advances services can be achieved.