The reason is that the network traffic volume has exceeded the APs' capacities. In most student dormitory buildings, each floor has three or four APs to avoid co-channel interference. Each AP usually provides signal coverage for at least six dormitories. In peak hours, there may be 20 to 30 students surfing on the Internet in an AP's coverage area. As a result, the required bandwidth exceeds the APs' capacities. Therefore, more APs are recommended in dormitory building with a high user density and high traffic volume. To avoid co-channel interference, antennas can be installed in dormitories.