Rural land mobile radio market assessment and satellite and terrestrial system concepts

Market potential exists; the nature of the market in terms of service needs, usage characteristics, service requirements, and forecasting the demand to the year 2000; alternative system cncepts that show promise in addressing the identified needs, in a cost effective manner; and advanced technology requirements associated with these concepts are considered

A Tracing JIT Compiler for Erlang using LLVM

We have modified the Erlang runtime to add support for a tracing just-in-time (JIT) compiler, similar to Mozilla’s TraceMonkey. Tracing is a technique to augment an existing interpreter with a JIT simply by recording the instructions executed during a loop iteration, and then generate optimized native code from this. Tracing compilers are particularly suited to optimize number crunching tight loops, an area where Erlang traditionally has been lacking. We make use of the LLVM compiler library to optimize and emit native code. In micro benchmarks we show some major improvements, reducing execution time by up to 75%. However, from an engineering point of view, we conclude that the effort of an industrial strength implementation would be substantial – essentially reimplementing large parts of Erlang’s interpreter – and discuss a potential solution based on recent research in the area.Nästan alla moderna programspråk använder en interpretator – en flexibel och praktisk om än långsam lösning. Vi prövar ett enkelt sätt att kraftigt öka prestandan på Erlangs interpretator

Parallel Discrete Event Simulation with Erlang

Discrete Event Simulation (DES) is a widely used technique in which the state of the simulator is updated by events happening at discrete points in time (hence the name). DES is used to model and analyze many kinds of systems, including computer architectures, communication networks, street traffic, and others. Parallel and Distributed Simulation (PADS) aims at improving the efficiency of DES by partitioning the simulation model across multiple processing elements, in order to enabling larger and/or more detailed studies to be carried out. The interest on PADS is increasing since the widespread availability of multicore processors and affordable high performance computing clusters. However, designing parallel simulation models requires considerable expertise, the result being that PADS techniques are not as widespread as they could be. In this paper we describe ErlangTW, a parallel simulation middleware based on the Time Warp synchronization protocol. ErlangTW is entirely written in Erlang, a concurrent, functional programming language specifically targeted at building distributed systems. We argue that writing parallel simulation models in Erlang is considerably easier than using conventional programming languages. Moreover, ErlangTW allows simulation models to be executed either on single-core, multicore and distributed computing architectures. We describe the design and prototype implementation of ErlangTW, and report some preliminary performance results on multicore and distributed architectures using the well known PHOLD benchmark.Comment: Proceedings of ACM SIGPLAN Workshop on Functional High-Performance Computing (FHPC 2012) in conjunction with ICFP 2012. ISBN: 978-1-4503-1577-

Hierarchical Beamforming: Resource Allocation, Fairness and Flow Level Performance

We consider hierarchical beamforming in wireless networks. For a given population of flows, we propose computationally efficient algorithms for fair rate allocation including proportional fairness and max-min fairness. We next propose closed-form formulas for flow level performance, for both elastic (with either proportional fairness and max-min fairness) and streaming traffic. We further assess the performance of hierarchical beamforming using numerical experiments. Since the proposed solutions have low complexity compared to conventional beamforming, our work suggests that hierarchical beamforming is a promising candidate for the implementation of beamforming in future cellular networks.Comment: 34 page

Types and Intermediate Representations

The design objectives and the mechanisms for achieving those objectives are considered for each of three systems, Java, Erlang, and TIL. In particular, I examine the use of types and intermediate representations in the system implementation. In addition, the systems are compared to examine how one system\u27s mechanisms may (or may not) be applied to another

Applicability of different onboard routing and processing techniques to mobile satellite systems

The paper summarizes a study contract recently undertaken for ESA. The study compared the effectiveness of several processing architectures applied to multiple beam, geostationary global and European regional missions. The paper discusses architectures based on transparent SS-FDMA analog, transparent DSP and regenerative processing. Quantitative comparisons are presented and general conclusions are given with respect to suitability of the architectures to different mission requirements

Mobile radio alternative systems study, executive summary

Present day mobile communication technologies, systems and equipment are described from background in evaluating the concepts generated in the study. Average propagation ranges are calculated for terrestrial installations in each of seven physiographic areas of the contiguous states to determine the number of installations that would be required for nationwide coverage. Four system concepts are defined and analyzed to determine how well terrestrial systems can fulfill the requirements at acceptable costs

Towards the Automated Verification of Weibull Distributions for System Failure Rates

Weibull distributions can be used to accurately model failure behaviours of a wide range of critical systems such as on-orbit satellite subsystems. Markov chains have been used extensively to model reliability and performance of engineering systems or applications. However, the exponentially distributed sojourn time of Continuous-Time Markov Chains (CTMCs) can sometimes be unrealistic for satellite systems that exhibit Weibull failures. In this paper, we develop novel semi-Markov models that characterise failure behaviours, based on Weibull failure modes inferred from realistic data sources. We approximate and encode these new models with CTMCs and use the PRISM probabilistic model checker. The key bene t of this integration is that CTMC-based model checking tools allow us to automatically and e ciently verify reliability properties relevant to industrial critical systems