Minimizing flowtime and maximum earliness on a single machine

We consider the bicriteria scheduling problem of minimizing flowtime and maximum earliness on a single machine. The problem is known to be NP-hard. We develop heuristic procedures for generating all efficient sequences for the cases where machine idle time is either allowed or not allowed. For both cases we also discuss an algorithm that finds the best of the approximately efficient sequences for a given objective function by generating only a small subset of those sequences. We present computational results which demonstrate that the heuristic procedures and the algorithms perform very well.     

On the downlink throughput of a broadband LEO satellite networkwith hopping beams

In this letter, we analyze the throughput of the downlink segment of a low Earth orbit (LEO) global broadband satellite network. The downlink design uses a set of hopping spot beams, each of which can he pointed independently to any fixed earth cell within the satellite footprint on a per-packet basis. We present upper and lower bounds on the downlink throughput as a function of the number of spot beams, the interference constraints, and the coverage area. The bounds provide insight into the interrelationship between various downlink parameters in the design process. The results are verified through Monte Carlo simulations     

Wavelength assignment algorithms for wavelength routedinterconnection of LANs

This paper addresses the wavelength assignment issues in interconnecting optical local area networks (LANs) in which a wavelength cannot be reused for local connections. Multiple LANs are connected using a wavelength routing bridge that may or may not support wavelength conversion. Static and dynamic approaches to partitioning of wavelengths for local and global traffic are compared using analysis and simulations. Under the static scenario, the wavelength set is partitioned into fixed sets of local wavelengths and global wavelengths. Dynamic wavelength assignment allows all traffic to use all the wavelengths and thus provides greater statistical multiplexing at the expense of increased implementation complexity. It is found that static wavelength assignment, the easiest algorithm to implement, is significantly outperformed by dynamic algorithms. Several dynamic assignment algorithms are developed, and architectural issues in interconnecting optical networks are discussed. The dependence of the call blocking performance on system parameters, such as the focal and global traffic statistics, and the number of available wavelengths is examined in detail. An elegant outcome is development of a simple, yet accurate, model to predict approximate blocking performance with an arbitrary number of LANs     

On the bit error rate of lightwave systems with optical amplifiers

The problem of evaluating the performances of communication systems with optical amplifiers and a wideband optical filter is addressed. Exact probability of error expressions for optical signals in presence of amplifier spontaneous noise and photodetector shot noise are given and compared with those predicted by Gaussian approximations for amplitude shift keying (ASK), frequency shift keying (FSK), or differential phase shift keying (DPSK) modulations, both for ideal photodetectors and for the case where shot noise is significant