Self-stabilizing ARQ on channels with bounded memory or bounded delay

It is shown that implementing self-stabilizing versions of standard ARQ (automatic-repeat-request) protocols, such as stop-and-wait or go-back-n, would require knowledge of a bound on the maximum delay or maximum memory of the communication channel involved. An alternative approach to self-stabilizing ARQ that incorporates a delay or memory bound directly as part of the communication model is given. Two ARQ protocols are presented that self-stabilize by using one bit of overhead in each transmitted message. The protocols operate exactly like standard stop-and-wait ARQ except that when a fault places them in an incorrect (unsafe) state, the additional bit in the protocol messages allows automatic recovery.<>