Nowadays, IEEE802.11n wireless local-area networks (WLANs) have been widely deployed due to its high-speed data transmission. The channel bonding is one of the key technologies to realize it. However, the data transmission throughput can be dropped when nearby multiple links are concurrently communicating, caused by interference. Previously, we have studied the throughput-drop estimation model for the links using the channel bonding, which considers the channel distance and the received signal strength (RSS) of the interfered links. In this paper, we further explore the throughput-drop estimation model for concurrently communicating two links without the channel bonding by extending the previous model. The effectiveness of the proposal is confirmed through experiments where the estimated throughput well matches the measured throughput.