We analyze the carrier sensing and interference relations between the two wireless links and measure the impact of these relations on link capacity in two indoor 802.11a mesh network testbeds. We show that asymmetric carrier sensing and/or interference relations happen frequently in wireless networks; these asymmetric relations affect not only the level of performance degradation, but also the fairness of channel access. We then propose a new methodology that predicts the relation of carrier sensing and interference based on radio signal strength measurements. The measurement complexity increases only linearly with the number of wireless nodes. To our knowledge, the proposed methodology is the first trial that considers physical layer capture, and detects the source of interference that is out of the communication range. We validate the prediction methodology on an 11-node wireless mesh network testbed.