in order to be able to test if the specific ANC-OL transmission is efficient (a subset of them in case of COOP). Therefore, a significant number of messages should normally be exchanged even in the simple network of Fig. \[fig:topology-mac-cc2\]. In this paper all the necessary channels are estimated by leveraging the transmission of existing control messages in order to avoid additional traffic. The precise algorithm that ensures minimum overhead is shown in Fig. \[fig:distributed-channel-estimation\], while it is described below in detail.

  ------- ------- ------- ------- ------- --------------------------------------------------------- --------------------------------------------------------- ------------------- ------------------------ -------------------------
   Src 1   Dst 1   Src 2   Dst 2   Relay                      $S\rightarrow D$                                  $S\rightarrow R$,$R\rightarrow D$              $\widetilde{R}^D$   $\widetilde{R}^{COOP}$   $\widetilde{R}^{ANCOL}$
   $N_1$   $N_2$     -       -       -                          $\tilde{h}_1$                                                   -                                      X                     -                         -
   $N_1$   $N_2$     -       -     $N_3$                        $\tilde{h}_1$                                      $\tilde{h}_2$,$\tilde{h}_4$                         -                     X                         -
   $N_1$   $N_2$     -       -     $N_6$                        $\tilde{h}_1$                                                   X                                      -                     X                         -
   $N_1$   $N_2$   $N_4$   $N_5$   $N_3$   $\tilde{h}_1$,$\tilde{h}_6$,$\tilde{h}_3$,$\tilde{h}_8$   $\tilde{h}_2$,$\tilde{h}_4$,$\tilde{h}_5$,$\tilde{h}_7$           -                     -                         X
   $N_1$   $N_2$   $N_4$   $N_5$   $N_6$                      $\tilde{h}_1$,...                                         $\tilde{h}_2$,...                              -                     -                         X
    ...                                                                                                                                                                                                    
  ------- ------- ------- ------- ------- --------------------------------------------------------- --------------------------------------------------------- ------------------- ------------------------ -------------------------

Every time a node associates with a specific wireless local-area network (WLAN) this algorithm is initiated while when it diss-associates (also because of mobility) the algorithm stops and the related 