On the Throughput of Channels that Wear Out

This work investigates the fundamental limits of communication over a noisy discrete memoryless channel that wears out, in the sense of signal-dependent catastrophic failure. In particular, we consider a channel that starts as a memoryless binary-input channel and when the number of transmitted ones causes a sufficient amount of damage, the channel ceases to convey signals. Constant composition codes are adopted to obtain an achievability bound and the left-concave right-convex inequality is then refined to obtain a converse bound on the log-volume throughput for channels that wear out. Since infinite blocklength codes will always wear out the channel for any finite threshold of failure and therefore cannot convey information at positive rates, we analyze the performance of finite blocklength codes to determine the maximum expected transmission volume at a given level of average error probability. We show that this maximization problem has a recursive form and can be solved by dynamic programming. Numerical results demonstrate that a sequence of block codes is preferred to a single block code for streaming sources.Comment: 23 pages, 1 table, 11 figures, submitted to IEEE Transactions on Communication

Experiments on meteor burst communications in the Antarctic

Two kinds of experiments on the meteor burst communication(MBC) are now being conducted in the Antarctic to study the ability of MBC as a communication medium for data collection systems in that region. In the first one, continuous tone signal is transmitted from Zhongshan Station. The received signal at Syowa Station about 1400km apart is recorded and analyzed. This experiment is to study basic properties of the meteor burst channel in that high latitude region. From the data available thus far, we can see that 1) the sinusoidal daily variation in the meteor activity typical in mid and low latitude regions can not be clearly seen, 2) non-meteoric propagations frequently dominate the channel, etc. On the other hand, the second experiment is to estimate data throughput of a commercial MBC system in that region. A remote station at Zhongshan Station tries to transfer data packets each consists of 10 data words to the master station at Syowa Station. Data packets are generated with five min interval. We are now operating the system only five min in each ten min interval. About 60% of the generated data packets are constantly transferred to the master station within two hours delay

VHF data transmission experiments using MBC equipment conducted during the period from JARE-43 to JARE-45

In order to study the ability of meteor burst communications (MBC) as a new medium of data collection networks in Antarctica, we have performed a series of VHF data transmission experiments. In the experiment during the period of JARE-43 (the 43rd Japanese Antarctic Research Expedition), a remote station at Zhongshan Station sent data packets to a master station at Syowa Station using a commercial MBC system. Together with meteor burst propagations, non-meteoric propagations were frequently observed during local nighttime. We found that they worked effectively for packet transmissions and greatly increased the data throughput. Overall data throughput obtained by this experiment was 0.63bps. In JARE-44, we added another remote station at Dome Fuji Station. Since the transmitted power from the master unit was split into two directions, data throughput from Zhongshan Station was reduced to 0.36bps. That from Dome Fuji Station was only 0.13bps. For the experiment in JARE-45, we replaced the commercial MBC system with a RANDOM (RAdio Network for Data Over Meteor) system developed by the authors. The experiment is being conducted between Syowa and Zhongshan Stations. The estimated data throughput during the period from April 1st, 2004 to August 31st, 2004 was 2.9bps

Spatio-Temporal Spectrum Holes and the Secondary User

DSA research must explicitly consider the perspective of secondary users. This paper considers the spatio-temporal properties of spectrum holes as they impact the secondary user’s communications needs. Like Weiss et.al. [1], this paper develops typology of spectrum holes from the point of view of the secondary user. Each type of spectrum hole is analyzed for the kinds of communications requirements that can be supported, illustrated, where possible, existing measurement data. The analysis concludes that a secondary user’s ability to meet their communications need varies considerably. More detailed analysis of the spatio-temporal density of spectrum holes would be necessary to further quantify these conclusions

Military Radio Communications Research in Australia

An overview of recent research by the Australian Defence Science and Technology Organisation in the field of military radio communications is presented. A philosophy for improving digital radio system performance over complex, variable channels is outlined. A key breakthrough, called PDF-directed adaptive radio, which can provide substantially greater throughput over HF channels whilst minimising bit-error rate and delay, is described. Simulation results for fast adaptive Schemes applied to both serial-tone and parallel-tone HF modems are presented and shown to significantly out-perform fixed rate modems and modems employing hybrid automatic-repeat-request schemes. A new detector scheme is discussed which has superior performance to conventional detectors for digital traffic in the presence of inter-symbol interference and impulsive noise

The study of an adaptive bit rate modem for meteor scatter communications

Includes bibliographical references

A plan for the collection and transmission of hydrometeorological data in the Brasilian Amazon basin

There are no author-identified significant results in this report

The IceCube Neutrino Observatory: Instrumentation and Online Systems

The IceCube Neutrino Observatory is a cubic-kilometer-scale high-energy neutrino detector built into the ice at the South Pole. Construction of IceCube, the largest neutrino detector built to date, was completed in 2011 and enabled the discovery of high-energy astrophysical neutrinos. We describe here the design, production, and calibration of the IceCube digital optical module (DOM), the cable systems, computing hardware, and our methodology for drilling and deployment. We also describe the online triggering and data filtering systems that select candidate neutrino and cosmic ray events for analysis. Due to a rigorous pre-deployment protocol, 98.4% of the DOMs in the deep ice are operating and collecting data. IceCube routinely achieves a detector uptime of 99% by emphasizing software stability and monitoring. Detector operations have been stable since construction was completed, and the detector is expected to operate at least until the end of the next decade.Comment: 83 pages, 50 figures; updated with minor changes from journal review and proofin

Potential markets for a satellite-based mobile communications system

The objective of the study was to define the market needs for improved land mobile communications systems. Within the context of this objective, the following goals were set: (1) characterize the present mobile communications industry; (2) determine the market for an improved system for mobile communications; and (3) define the system requirements as seen from the potential customer's viewpoint. The scope of the study was defined by the following parameters: (1) markets were confined to U.S. and Canada; (2) range of operation generally exceeded 20 miles, but this was not restrictive; (3) the classes of potential users considered included all private sector users, and non-military public sector users; (4) the time span examined was 1975 to 1985; and (5) highly localized users were generally excluded - e.g., taxicabs, and local paging