Grandstream Networks GWN7610 Deployment Manual page 32

If the air environment is very idle. For example, only a few APs are deployed, and the planning for channel
multiplexing are performed efficiently. Most of the time, the AP will be able to achieve the full speed with
80MHz bandwidth.
If the AP is deployed in a high-density environment and the same-channel and adjacent-channel
interference is large, the AP can hardly find the available bandwidth of 80MHz, then AP will perform channel
bandwidth fallback.
•
40MHz primary channel is idle, 40MHz secondary channel is busy, then use 40MHz bandwidth to
send data frames;
•
If the 40MHz bandwidth channel is also busy, then detect whether 20MHz primary is idle, and if it
is idle, send 20MHz bandwidth data frame, otherwise, perform collision avoidance.
Under the bandwidth detection mechanism, the rate of each data frame may not be completely constant,
it's depended on the channel bandwidth used by each frame and the location of the client.
Compared with 802.11n, this mechanism increases the flexibility of channel bandwidth usage. However, it
requires a bandwidth detection cost, which is continuously sending CTS.
In actual 802.11ac deployment, the primary 20MHz channel of adjacent AP can be selected between
CH36~48 and CH149~165 in turns, so the frequency will be isolated. For example, AP1 selects CH36
40MHz bandwidth, adjacent AP2 choose CH149 40MHz bandwidth, and so on. Of course, in actual
deployment, we also need to consider other interferences.
c) Channel transmission power
The WLAN network is a microcell. Its Wi-Fi module of the terminal cannot be compared with the 3G/4G
radio module on mobile communication, and the uplink is lack of compensation. So, try to reduce your AP
power!
For indoor deployment, it is necessary to consider the signal loss caused by building walls, furniture, doors
and windows, and even human activities. For outdoor deployment, the signal loss caused by the buildings,
landscapes, and vehicles need to be considered;
The estimation of the receiving power strength usually uses the following formula:
*Pr[dBm] = *Pt[dBm] + *Gt[dBi ] – PI[dB] + Gr[dBi]
*Pr[dBm] is receiving signal power strength;
*Pt[dBm] is maximum transmission power;
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