An algorithm for adaptive retransmission in a slottedALOHA communication channel has been designed and implemented. This algorithm maintains the stability of the slotted-ALOHA channel under a wide variety of conditions and provides improvements in the response time of the channel. Simulation was used to test the algorithm for steady-state and impulse response. The algorithm was compared to a binary exponential backoff algorithm by simulation and was found to provide better response time.

A Dual-Mode Slotted TDMA Digital Bus has been designed and a prototype system has been built. This type of bus is a hybrid design which provides optimized bandwidth usage when such a system contains a combination of users with high duty cycle and/or synchronous data and low duty cycle asynchronous data. High duty cycle and/or synchronous users are assigned dedicated slots as in MITRIX. Low duty cycle asynchronous users are assigned a common set of contention slots as in slotted ALOHA. To assure both good response time and system stability, an algorithm was developed to compute an adaptive mean retransmission delay for the ALOHA slots. This paper discusses the theory behind the Dual-Mode Slotted TDMA Bus and provides supporting data determined by simulation.