Approximate analysis of a bidirectional looped dual‐bus network

The characteristics of a system consisting of a number of terminals (queues) connected to two buses with slots in opposite directions are analyzed here. Cells arrive independently at each terminal and are sent to a gateway station on an empty slot. In addition, cells to be emptied at terminals may be loaded on the slots transmitted from the gateway station. Such a slot can be utilized by a destination terminal and its downstream terminals. A bidirectional bus structure is used to alleviate unfairness among terminals and to improve system reliability. A rigorous solution of a basic model consisting of only one queue is first obtained in analyzing this system. Next, an approximate analysis is performed on the target model utilizing the foregoing result. Since rigorous analysis of the characteristics of the target model is difficult, two approximate analyses are proposed here. the validity of these approximate analyses is evaluated by making comparisons with simulation results. the results indicate that the analyses presented in this paper are useful and are sufficiently accurate for the case without cell unloading.