On Opportunistic Cooperation for Improving the Stability Region with Multipacket Reception

We investigate the composite effects of multipacket reception (MPR) and relaying capability in affecting the stability region of a wireless network. With a general MPR channel, a trade-off arises as to whether to activate the relay simultaneously with the source so that both transmissions might be successful, or to let the relay remain silent to overhear the source’s transmission and then activate the cooperation. As such, we consider a two-user multiple-access system where the user with a better user-destination channel may act as the relay for the other. An opportunistic cooperation scheme through scheduling the relay’s transmission is proposed. Then the optimal scheduling probability for maximizing the stability region is characterized, and the corresponding stability region is derived. We show that the stability region of the opportunistic scheme may be convex under certain channel conditions, and may strictly outer-bound the stability region of the conventional cooperation scheme.