Algorithm 5. Broadcast message receiving process for clustering phase (pseudo-code).

Input: msg, cluster, isCH, hopsToCH, clusterSize, CH_RSSI Output: Unicast_msg, cluster, isCH, hopsToCH, clusterSize (1)  If sender is defined in the neighbor list then      update neighbor node data     node.cluster $\leftarrow$ msg.cluster;     node.isCH $\leftarrow$ msg.isCH;     node.hopsToCH $\leftarrow$ msg.hopsToCH;     node.RSSI $\leftarrow$ max(RSSI); (2)  Else add new neighbor to the list     initialize new neighbor data     node.cluster $\leftarrow$ msg.cluster;     node.isCH$\leftarrow$ msg.isCH;     node.hopsToCH $\leftarrow$ msg.hopsToCH;     node.RSSI $\leftarrow$ msg.RSSI; (3)  If cluster = 0 or node.cluster$\ne$cluster then (4)  If (node.isCH$=1$ and isCH$\ne$1) then (5)    If cluster = 0 or (cluster$\ne$0 and hops = 0 and node.RSSI > CH_RSSI) then        cluster$\leftarrow$ node.cluster;        hops$\leftarrow$ 0;        CH_RSSI$\leftarrow$ node.RSSI;        clusterSize$\leftarrow$ node.clusterSize + 1; (10)   If (node.isCH$\ne 1$and isCH$\ne$1) then (11)     If (hops$>$1 and hops$>$node.hops + 1) or (hops = 0 and cluster = 0 and node.cluster$\ne$0) then        cluster $\leftarrow$ node.cluster;        hops$\leftarrow$ node.hops + 1;        clusterSize$\leftarrow$ clusterSize + 1; else        cluster Size $\leftarrow {\sum }_{i=1}^{N_j}clusterSize/N_j$, where $N_j$ is the number of neighbors which belong to the same cluster as the sensor node. (12)   msg.clusterSize $\leftarrow$ clusterSize;     msg.cluster $\leftarrow$cluster; load msg; send Unicast(msg);