An extended token bus protocol for embedded networks

A network environment is considered that can exist in commercial and military products, such as automatic guided vehicles, that use sensors and processors for movement, attack, defense and communication. A bus protocol called IMAP (improved token bus multiaccess protocol) is proposed for these embedded networks. Two modes of operation are defined for the protocol. The normal mode occurs when token passing is done in a random order and the token remains within a cluster of active stations. For a nonuniform traffic condition, this mode of operation can be interrupted by a mode in which token bus operation is carried out and the token is passed through every station. The performance (channel utilization and delay characteristics) of IMAP are compared to those of the token bus and CSMA/CD (carrier sense multiaccess with collision detection) and shown to be superior