Compare 2.4Ghz vs 5Ghz

2.4 Ghz has 3 non-overlapping 20Mhz width channel while 5Ghz has 11 to 24 * 20Mhz non-overlapping channel. So, the possibility of co-channel interference in 2.4Ghz is higher than the possibility in 5Ghz, and more bandwidth could be provided in 5Ghz by installing more AP in small area while avoiding co-channel interference.

With 802.11n, 40Mhz width could be used in 2.4Ghz, but it will be shrink to 20Mhz bandwidth if there is co-channel interference. With 802.11N and 802.11AC, up to 160Mhz channel width could be used in 5 Ghz.

However, the attenuation rate in 5Ghz is higher than the one in 2.4 Ghz because of high level of attenuation in higher frequency by obstacle or absorptive attenuation by air or water.So, the coverage by ap running in 2.4Ghz is wider than the coverage of AP running in 5Ghz, and 2.4Ghz is appropriate for the place where require wider range of coverage with less number of user and APs.