Improvements in TDMA circuit switching services on a tree‐shaped broadband network

Abstract

This paper attempts to realize the TDMA circuit switching service on the broadband tree-shaped network applying the two-way coaxial CATV techniques. The improvement of the time-slotted bus system with controller window proposed previously by the authors is dis-CUSSed.To make this system practical, such problems as simplification of terminal device and expansion of service scale must be solved. For this purpose, the "center measurement method" and the "variable width control window method" are developed anew. The former is a system which measures such parameters as the round-trip transmission delay at the central control device and notifies the terminal of the result.By improving the down-link transmission quality of the control window, which is important from the viewpoint of the stable operation of the whole system and by reducing the high-speed operation functions, the terminal 1 device is simplified. The latter is to adjust the control window width according to the traffic. By this scheme, the number of contained time-slots, i.e., the number of serviceable subscribers, can be increased without reducing the wide service area of the broadband tree-shaped network. A prototype system was constructed based on those two system improvements, and an experimental evaluation was attempted on the experimental two-way CATV system with a total length of 7.9 km. As a result, it was verified that the foregoing improvements are useful and matched to each other.