The results of a traffic study undertaken to determine if a 64 kb/s common-signalling channel is sufficiently fast to meet the present and future call-processing needs of integrated digital loop-carrier (IDLC) systems are presented. Bell Communications Research (Bellcore) has proposed the use of such a 64 kb/s common signalling channel in a requirement document, technical reference TR-TSY-000303, to satisfy call-processing needs across the IDLC generic interface, whenever out-of-band signalling is used. The IDLC call-processing traffic on this message-oriented common-signalling channel is characterized, and associated design requirements in TR-303 under certain modelling assumptions (Poisson arrivals and exponential service time) are examined. Under worst-case conditions, it is concluded that a critical message requiring a response within 100 ms would practically always meet that delay criterion. Critical messages requiring a response within 40 ms would fail once every 10 busy hours. Since no specific signalling response requirement of 40 ms has been found, the authors conclude that a 64 kb/s common-signalling-channel for IDLC system is sufficiently fast to achieve required signalling response times.>

This paper reports the results of a study aimed at understanding the design process for fiber optic systems in subscriber lines, also known as loop network. Since loop spans are typically shorter and traffic volumes lower than interoffice trunks, the required performance level of a fiber optic system is often less than the maximum Obtainable from the technology. This affords us an opportunity to save money by designing a fiber optic system truly tailored to the application. The design problem is approached from an optimization point of view. A nonlinear programming model was formulated and solved for determining the optimal values of fiber attenuation, splicing loss, system gain and operating wavelength. The sensitivity of key parameters has been studied. We show that considerable savings can be realized if the components are selected based on the optimum values given by the model. The cost penalty is also calculated for nonoptimum designs. This study lays the groundwork for developing design techniques to be used by engineers in designing fiber optic systems and also for establishing the technical requirements of various fiber optic system components.