in wireless networks, the exposed node problem occurs when a node is prevented from sending packets to other nodes because of co-channel interference with a neighboring transmitter. consider an example of four nodes labeled r1, s1, s2, and r2, where the two receivers (r1, r2) are out of range of each other, yet the two transmitters (s1, s2) in the middle are in range of each other. here, if a transmission between s1 and r1 is taking place, node s2 is prevented from transmitting to r2 as it concludes after carrier sense that it will interfere with the transmission by its neighbor s1. however note that r2 could still receive the transmission of s2 without interference because it is out of range of s1.