Global Scheduling Approach to Conflict-Free Multiaccess via a Data Bus

A global scheduling multiple access (GSMA) scheme for data communication via a high speed bus is described. The GSMA scheme, which has a variable length frame format and the desirable property of guaranteeing each active user a minimum service per frame, attains conflict-free multiaccess and has the flexibility of providing more channel capacity to the large users. An expression for the mean system delay under a Poisson arrival law and an imbalanced loading (multi-rate) environment is derived. Numerical results indicate that the GSMA scheme offers substantially higher channel utilization compared to the synchronous time-division multiple access (STDMA) scheme, particularly at the low throughput region. It is shown also that the GSMA system offers superior delaythroughput performance to an STDMA or POLLING system.