On the practical issues of implementing the VTPE-hBEB protocol in small processing power controllers

VTPE-hBEB is a protocol suitable to transmit realtime traffic on top of shared Ethernet, enabling the coexistence of specific real-time stations and legacy stations. It operates by letting one station at a time to disable the back-off algorithm for collision resolution. This privilege is shared among stations by a virtual token rotation mechanism. The implementation of this protocol with reduced processing power microcontrollers requires adaptations to be made on the determination of fundamental parameters such as the token rotation time. In this paper a timing analysis that takes into consideration the limitations of such processors is derived and validated with a set of experiments in which parameters such as the token rotation time and the message delay are measured.