55,262 research outputs found
Don't Repeat Yourself: Seamless Execution and Analysis of Extensive Network Experiments
This paper presents MACI, the first bespoke framework for the management, the
scalable execution, and the interactive analysis of a large number of network
experiments. Driven by the desire to avoid repetitive implementation of just a
few scripts for the execution and analysis of experiments, MACI emerged as a
generic framework for network experiments that significantly increases
efficiency and ensures reproducibility. To this end, MACI incorporates and
integrates established simulators and analysis tools to foster rapid but
systematic network experiments.
We found MACI indispensable in all phases of the research and development
process of various communication systems, such as i) an extensive DASH video
streaming study, ii) the systematic development and improvement of Multipath
TCP schedulers, and iii) research on a distributed topology graph pattern
matching algorithm. With this work, we make MACI publicly available to the
research community to advance efficient and reproducible network experiments
An information and communications technology (ICT)-enabled method for collecting and collating information about pre-service teachers' pedagogical beliefs regarding the integration of ICT
This paper describes a method that utilized technology to collect and collate quantitative and qualitative data about preâservice teachersâ use of networked technologies during a 12âweek undergraduate course, and the impact of this use on their pedagogical beliefs regarding the integration of information and communications technology (ICT). The technologies used captured and analysed studentsâ spoken and written communication while engaging in four synchronous online tasks, and also collected evaluation data from online interviews, surveys and diaries. The richness of data afforded by this ICTâenabled method enabled the research to produce a rich narrative of how the students used the technology and provided evidence of a change in preâservice teachersâ pedagogical beliefs during the course
Bandwidth efficient multi-station wireless streaming based on complete complementary sequences
Data streaming from multiple base stations to a client is recognized as a robust technique for multimedia streaming. However the resulting transmission in parallel over wireless channels poses serious challenges, especially multiple access interference, multipath fading, noise effects and synchronization. Spread spectrum techniques seem the obvious choice to mitigate these effects, but at the cost of increased bandwidth requirements. This paper proposes a solution that exploits complete complementary spectrum spreading and data compression techniques jointly to resolve the communication challenges whilst ensuring efficient use of spectrum and acceptable bit error rate. Our proposed spreading scheme reduces the required transmission bandwidth by exploiting correlation among information present at multiple base stations. Results obtained show 1.75 Mchip/sec (or 25%) reduction in transmission rate, with only up to 6 dB loss in frequency-selective channel compared to a straightforward solution based solely on complete complementary spectrum spreading
Turbo-Detected Unequal Protection MPEG-4 Wireless Video Telephony using Multi-Level Coding, Trellis Coded Modulation and Space-Time Trellis Coding
Most multimedia source signals are capable of tolerating lossy, rather than lossless delivery to the human eye, ear and other human sensors. The corresponding lossy and preferably low-delay multimedia source codecs however exhibit unequal error sensitivity, which is not the case for Shannonâs ideal entropy codec. This paper proposes a jointly optimised turbo transceiver design capable of providing unequal error protection for MPEG-4 coding aided wireless video telephony. The transceiver investigated consists of space-time trellis coding (STTC) invoked for the sake of mitigating the effects of fading, in addition to bandwidth efficient trellis coded modulation or bit-interleaved coded modulation, combined with a multi-level coding scheme employing either two different-rate non-systematic convolutional codes (NSCs) or two recursive systematic convolutional codes for yielding a twin-class unequal-protection. A single-class protection based benchmark scheme combining STTC and NSC is used for comparison with the unequal-protection scheme advocated. The video performance of the various schemes is evaluated when communicating over uncorrelated Rayleigh fading channels. It was found that the proposed scheme requires about 2.8 dBs lower transmit power than the benchmark scheme in the context of the MPEG-4 videophone transceiver at a similar decoding complexity
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