In this paper, we evaluate and analyze a proposed scheme for collision detection in wireless local area networks (WLANs) by computer simulations and theoretical calculations. The proposed scheme utilizes the medium access control (MAC) procedure of multiple-input multiple-output (MIMO) transmission technology, which has been used to achieve transmission with a high link rate in WLANs in recent years; however, the transmission efficiency degrades at the MAC data service access point (SAP), although a high transmission link rate is achieved at the physical (PHY) layer. The transmission efficiency achieved by the proposed scheme is confirmed at a high level of approximately 97% when used with an aggregation MAC protocol data unit (A-MPDU) by computer simulations, which is better than that of Ethernet. An A-MPDU has the effect of improving the transmission efficiency because it achieves a burst transmission of data packets. Furthermore, the results of our theoretical calculations correspond with the computer simulation results, indicating that the proposed scheme is indeed efficient and reliable.