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In most existing studies of wavelength-division multiplexing networks, the problems of routing and wavelength assignment are generally treated separately, since it is NP-complete to produce the optimal solutions for the two problems at the same time. Our four adaptive routing algorithms presented in this paper, however, consider the availability of wavelengths during the routing process. Our algorithms favor paths with near-maximum number of available wavelengths between two nodes, resulting in improved load balancing. Simulations show that our algorithms reduce call blocks nearly by half when compared with the least-loaded and the k-fixed routing algorithms in some small networks using the first-fit wavelength assignment policy. In addition, simulation and analysis show that the path length of our algorithms is almost the same as those of the other algorithms. [ABSTRACT FROM AUTHOR]

Shows that there exists a spectrum of block replacement policies in computer memory that subsumes the two seemingly unrelated and independent Least Recently Used (LRU) and Least Frequently Used (LFU) policies. Spectrum of implementations of the LRFU that again subsumes the LRU and LFU implementations; Comparison of the LRFU policy with other policies; Combined effects of λ and correlated period on the performance of the LRFU policy.

An accurate and safe estimation of a task's worst case execution time (WCET) is crucial for reasoning about the timing properties of real-time systems. In RISC processors, the execution time of a program construct (e.g., a statement) is affected by various factors such as cache hits/misses and pipeline hazards, and these factors impose serious problems in analyzing the WCETs of tasks. To analyze the timing effects of RISC's pipelined execution and cache memory, we propose extensions to the original timing schema where the timing information associated with each program construct is a simple time-bound. In our approach, associated with each program construct is worst case timing abstraction, (WCTA), which contains detailed timing information of every execution path that might be the worst case execution path of the program construct. This extension leads to a revised timing schema that is similar to the original timing schema except that concatenation and pruning operations on WCTAs are newly defined to replace the add and max operations on time-bounds in the original timing schema. Our revised timing schema accurately accounts for the timing effects of pipelined execution and cache memory not only within but also across program constructs. This paper also reports on preliminary results of WCET analysis for a RISC processor. Our results show that tight WCET bounds (within a maximum of about 30% overestimation) can be obtained by using the revised timing schema approach. [ABSTRACT FROM AUTHOR]

Proposes a framework for solving the link assignment problem associated with the use of intersatellite links in low earth orbit satellite networks. Information on the framework; What is allowed by the finite state automation based framework; Details on what is used by Iridium and Calling low earth orbit satellites.

Proposes a technique used in the analysis of cache-related preemption delays in fixed-priority preemptive scheduling. Steps which the techniques consists of; Information on real-time systems; Schedulability analysis in fixed-priority scheduling; Details on caches in real-time systems.