User unsuppressible protocol sequences for collision channel without feedback

A revisit of the model of collision channel without feedback (CCw/oFB) has motivated some interesting designs on periodic binary sequences. The protocol and system simplicity is particularly favorable for applications in certain wireless sensor and ad hoc networks. User unsuppressibility for individual service guarantee is desirable and emphasized here. We review some protocol sequences that are user unsuppressible (UU). Lower bounds of sequence length are obtained. Some corresponding sequence sets are identified.