a suitable analytical rate expression (E.g. [@katabi07a]). Also for the ANC-OL mode to be more efficient than COOP in addition to inequality , the following condition must be true: $$\begin{aligned}
\label{ineq:4}
\frac{L}{\widetilde{R}_{ANCOL}}+T_{OVHD,ANCOL}<\frac{L}{\widetilde{R}_{COOP}}+T_{OVHD,COOP}.\end{aligned}$$ Relays use the previous rate estimation expressions for estimating the possible rate between for all the available channel estimates that they have stored for their neighbors. These results populate a data structure like the one depicted in Table \[tab1\], and in this case we name it $\mathbf{rate\_estimates}$. As we will see in the next section, a relay decides if it will notify another node regarding its ability to cooperate with the use of busy tones. A busy tone is a narrowband signal transmitted at the maximum allowed power of the wireless standard. This is accomplished on-demand, i.e. when another node desires to transmit.

Cooperative ANC MAC (CANC-MAC) {#sec:coopmac}
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The two previous algorithms for cooperative channel information exchange and rate estimation are essential for the operation of our system but they do not affect directly the channel access mechanism. Now we describe the third central component of the complete system that is the cooperative analog network coding MAC (CANC-MAC) protocol. The proposed protocol does not affect the contention 