Nowadays, the IEEE 802.11n wireless local-area network (WLAN) has been widely used in the Internet access service due to simple installations, low cost devices, and easy extensions. A number of access-points (APs) are often installed in a service field, which may cause high radio interferences among wireless links and result in the poor performance. To address this problem in the dense WLAN, previously, we have proposed the transmission power optimization method for concurrently communicating APs when every AP uses the channel bonding (CB). CB can enhance the transmission capacity by bonding two adjacent channels into one. The method selects either the maximum or minimum power for each AP such that the average signal-to-interference ratio (SIR) among all the APs becomes largest, after the required receiving signal strength (RSS) is measured with the possible power combinations. However, it has been observed that the use of non-CB at APs sometimes offers the higher throughput when they are closely located. CB reduces the number of non-interfered channels and makes wireless links susceptible to interferences. In this paper, we investigate the applicability of the transmission power optimization method in the WLAN of three APs using both CB and non-CB. Extensive experiments were conducted under three network topologies using Raspberry Pi for APs and Linux PCs for hosts. The results confirmed the effectiveness of the method in any combination of CB and non-CB usage for the three APs.