Circuit Demand Research Articles

Configurable M-factor VLSI DVB-S2 LDPC decoder architecture with optimized memory tiling design

Semi-parallel architectures for decoding Digital Video Broadcasting-Satellite 2 (DVB-S2) Low-Density Parity-Check (LDPC) codes have improved Very Large Scale Integration (VLSI) solutions, but their design is challenging from several perspectives. In order to conveniently exploit parallelism for obtaining VLSI LDPC decoders that occupy small circuit areas and demand low power consumption, we propose in this article a novel ASIC reconfigurable approach that exploits efficiently the memory block reshaping required to use a reduced number of processor nodes. We exploit different memory tiling configurations to reduce the memory area about 20%. The proposed architecture was synthesized for a 90 nm process design with a variable number of processor nodes and a competitive circuit area of 6.2 mm2 was achieved. The operating frequency simultaneously guarantees throughputs superior to 90 Mbps, as required by DVB-S2, and low levels of power consumption.

Comparative economic analysis between direct and indirect wiring in the copper-based local loop

In a copper-based local loop, a circuit pair is indirectly connected to each subscriber usually via a primary cross connection point (PCP) which acts as a buffer to absorb circuit demand fluctuations among subareas. But some telephone operators adhere to the classic practice of direct wiring based on technological preferences without taking advantage of cost-efficient flexibility points. We analyse the extra cost of maintaining the old practice of direct wiring over the popular one using flexibility points in a single PCP area. For that, the expectation of circuit shortages in subareas during a single replenishment period for the direct wiring is first obtained. Exploiting the convexity of the expectation, we then present a procedure for optimally allocating circuits among subareas, which not only serves its own purpose of circuit provisioning for the direct wiring but also precisely calculates the extra cost over the indirect case.

REFORMA - a tool based on PC for telecom network optimization

This contribution presents the software tool REFORMA, which will support the tasks of telecommunication network planning departments. It is shown that REFORMA offers various possibilities for circuit demand routing, grouping and stand-by network optimization applied to local and trunk networks with digital transmission systems. The large flexibility to implement different planning rules and network development strategies with REFORMA is demonstrated by some network examples. Further extensions and applications of this tool are also indicated.

Optimal routing in circuit switched communication networks

Consideration is given to the optimal circuit routing problem in an existing circuit-switched network. The objective is to find circuit routing which accommodates a given circuit demand while maximizing the residual capacity of the network. In addition, the cost of accommodating the circuit demand should not exceed a given amount. Practical considerations require that a solution be robust to the variations in circuit demand and cost. The objective function for the optimal circuit routing problem is not a smooth one. In order to overcome the difficulties of nonsmooth optimization, the objective function is approximated by smooth concave functions. The optimization algorithm for the circuit routing problem is obtained as a limiting case of the sequence of optimal routing strategies for the corresponding smooth convex optimization problems, and the proof of its convergence to the optimal solution is given. An approach to calculating the optimal multicommodity flow is presented. The optimization algorithm efficiently handles networks with a large number of commodities, satisfies the robustness requirements, and can be used to solve circuit routing problems for large networks. >

A Terminal Bay Relief Strategy

This paper explores a new, more optimal policy for planning terminal bays for the provisioning of circuits in a telephone operating company. This new policy regularly monitors the terminal bay inventory and orders K units when the spare reaches a certain parameter, R. For particular office characteristics the optimal (R, K) pair which minimizes cost is determined, subject to a performance constraint. A probabilistic circuit demand model is formulated and a combination of simulation and analytic approximation is used to calculate the cost and performance measure. In order to prove that the new policy is more economical, the new policy is compared, via another simulation, to the present policy of a typical telephone operating company.

Economies of Scale, Networks, and Network Cost Elasticity

A foundation for examining network economy of scale effects is presented. A natural measure of the network scale effect is the network cost elasticity e, defined as the ratio of the fractional decrease in network average cost per circuit mile to the fractional increase in total circuit miles carried by the network. The maximum scale effect is given by e = 1 while e = 0 signifies no scale effect. The value of e can be estimated by comparing two network plans, one with nominal circuit demands and one with small variations in the demands. For a static network model, e can vary from 0 to 0.75 for several possible ways of changing each point-to-point circuit demand. The complex point-to-point nature of network demand must be included in any meaningful study of network scale effects. A simple example is used to show that static studies, while providing useful insight, have little relevance to issues concerned with a communications network evolving over time. A dynamic model of network evolution is presented which includes the point-to-point nature of demand and the sequential nature of facility installation decisions. A low-cost plan is developed for a nominal and slightly modified demand forecast. The transmission facilities assumed available are the same for both plans. However, advances in transmission technology during the study interval must be allowed in both plans if the results are to have relevance.