• B/G/N/AC
• Performance
• Mixed mode
• Dual module: B/G + N
• Indor coverage
• Seamless roaming
• Power setup
• 2.3 GHz and bridges

B/G/N/AC

You can find detailed description in http://en.wikipedia.org/wiki/IEEE_802.11. Brief practical info:

B, IEEE 802.11b - up to 11 marketing Mbit/s, rather old standard, uses 2.4 GHz. Real transfer rate ~5 Mbit/s duplex. Accepts about 10 clients in Access Point mode without significant transfer rate degrade. There are 13 frequency-divided channels available.

G, IEEE 802.11g - up to 54 marketing Mbit/s, was the most popular standars for a long time, also uses 2.4 GHz. Real transfer rate is about 21 Mbit/s duplex (2.1Mb/s). Accepts about 20-30 clients in Access Point mode without significant transfer rate degrade. Estimated transfer rate in such case is about 0.5 Mbit/s per client. We should take into account that we use shared media and packet collisions may occure (like on 10 MBit/s ethernet). Performance degrade is non-linear. Also, the most close clients have priority. There are 13 frequency-divided channels available. Actially, these channels are overlapping. Independent chanels (non-overlapped) are 1,6,11. Or 4 and 10. There must be distance of 6 between channels to avoid interference. Some devices support 14th channel far beyond 13th, which doesn't overlap 11th channel and lower ones. Note, most Apple devices doesn't support 12th and 13th channels.

G-turbo, Super-G - Sorry, In Russian only yet.

Mixed mode

Room Coverage

The main issue is walls, greater distances - less frequently. The more a signal travels through a wall, the more it weakens. Seems obvious. It's often overlooked that even when passing diagonally through a thin wall, a distance of 10-15 cm turns into 1-2-3 meters. That is, it won't work. Therefore, equipment should be placed, if possible, in a location from which the signal will pass directly through the walls that separate the required rooms.

Metallic walls are a special case. You need to reduce the transmitter's power and turn off the Short GI (guard interval) to reduce echo and interference from the access point with itself. If there's such a setting - decrease the base speed in the modulation settings (where you see 6, 12, 24, 36, 48, and 54).

If the signal in remote rooms is still low, you may have to install additional access points. Ideally, you would run a wire there, set up the second point on a different channel, but with the same SSID (network name) and the same authentication settings. This would result in WiFi roaming, and clients will automatically switch to the best access point. For information on which channels are independent, see above. (and below too) Important note:

• The first device operates in router mode
• The second device is set up in access point mode, DHCP is turned off on it, and it is connected to the LAN port of the first device.

"Seamless" Roaming

Attention! This is not a Mesh. Mesh is also an interesting technology, it works well (really not ;) when there are many access points, large coverage, and few clients - significantly fewer than access points. If the number of clients is comparable to or greater than the number of access points, it will not work properly.

• Ensure all access points are consistently configured (in terms of channel width, SSID, password, and encryption type). Only the power and channel settings should differ. This uniformity prevents clients from latching onto a distant yet faster access point instead of switching to a nearby slower one. You can use different (from 2.4GHz) channel width for 5GHz, but still same among all 5GHz devices.
• Turn off X TKIP and retain only X AES encryption, enhancing both security and compatibility, especially with newer iPhones and specific laptop Wi-Fi drivers. Also, TKIP prevents Ap from running transfer rates above 54Mbit/s. Note: unfortunately, disabling TKIP breaks compatibility with very old devices.
• Use X WPA-PSK/PSK2/PSK3 settings.
• Activate X MIMO.
• Use static IP X for Access Point.
• Enable X Transparent bridge (if any)
• Disable X DHCP
• Disable X WMM
• Disable X WDS
• Disable X airMax
• Disable X STP, MSTP, network discpovery, and all similar features. Block/disable these protocols on network switches too.
• All points (in access point mode) are connected by a cable to the central router either directly or via network switches; using repeaters is highly undesirable. If router doesn't operate normally in access point mode keep it in default mode and connect to uplink via LAN port
• For 2.4GHz:
  • With a 20MHz bandwidth, use non-overlapping channels: 1, 6, or 11. Devices like some Japanese gadgets and iPhones might face issues beyond channel 11. Strategically assign frequencies to minimize interference between access points operating on the same channel.
  • For the 40MHz setting, which is effectively 20+20, set the main channel and an auxiliary channel either higher or lower based on your device settings. This ensures minimum overlap and optimal performance.
  • Keep in mind that 2.4GHz frequency penetrates dry wood and brick quite effectively, struggles a bit with concrete, and barely passes through metal. Avoid placing access points on the same frequency directly opposite each other if a wall separates them. This frequency also gets absorbed significantly by water, so in crowded or plant-rich environments, elevate your access points.
• For 5GHz:
  • Utilize the broader range of independent channels, with 20MHz options at 36, 40, 44, 48.
  • Deploy 40MHz on channels 36(+40) and 48(+42).
  • The 80MHz setting spans all channels between 36 and 48.
  • Additional ranges like 52-64, 100-144, and 149-177 are available, but not all devices support them. As with 2.4GHz, manage the primary and auxiliary channels strategically to prevent potential speed drops during overlap.
  • Remember that 5GHz is excellent with dry wood, decent with brick, struggles with concrete, and is entirely blocked by metal.
• Using this knowledge, position the equipment and chose channel (fixed !) in such a way that the points operating on the same channel see each other as poorly as possible. And if it's not possible to completely isolate them, ensure that other points on the same channel give a signal strength no higher than -60db. View the actual picture in Wifi Analyzer Android/ iPhone. It should be noted that it displays the status with a delay of up to a minute. If the signal strength for the client from the nearest point is weaker than -50db, performance will be poor; below -60db, only messengers will work; at -70db, there will be no connection.
• A crucial point unrelated to WiFi: If your ISP doesn't support IPv6, or if you aren't distributing it to clients, ensure you fully X disable it on the local-facing interface. Additionally, filter out X DNS responses to remove AAAA records. For bind, use the command: filter-aaaa-on-v4 yes;. This is because some applications cannot correctly detect broken IPv6 connectivity and clients may experience missing incoming calls in messenger apps, like Signal

Attention! If you are using Outdoor access points in 5GHz, pay attention to the radar settings and DFS. Because when using DFS/RD channels, see https://en.wikipedia.org/wiki/List_of_WLAN_channels, upon detecting an external signal on the same frequency, the access point might (and generally should) turn off the radio module. Use allowed channels or switch to indor mode.

Completely Wireless

If it's impossible to run a wire to the second device, they can be connected wirelessly. However, there's a catch. If you set up the 2nd point in repeater mode (repeater), the overall bandwidth of the network will drop by half. This is because the repeater both receives and sends the signal simultaneously in all directions. If this solution satisfies the client and they are 200% sure about it, then it's OK.

Note: This requires meticulous configuration that involves monitoring the signal level in the room, adjusting power, etc. With standard firmware on "home" devices, results aren't guaranteed. When using OpenWRT, the chances are higher.

The correct setup is as follows:

1. A router with DHCP enabled on channel 1.
2. An access point in AP-client mode - meaning it connects to the router [1] as a client (bridge) via WiFi. You cannot connect to it wirelessly (i.e., the Access Point capability is disabled), and DHCP is also turned off. It operates on the same channel 1. Its only task is to connect router [1] with another access point [3].
3. An access point set to an independent channel (e.g., 11), but with the same network settings (SSID) and security (encryption, key, etc.) as router [1]. DHCP is turned off, and its WAN port is connected via a short copper patch cord to the LAN port of the repeater (AP-client, bridge) [2].

Power Settings

You should set the power as low as possible while maintaining a stable connection even in the far reaches of the room. An excessively powerful signal:

1. Reflects off walls and creates noise in the room, which can degrade the quality of the connection.
2. "Blinds" nearby receiving devices.
3. Reduces the reception quality for neighbors, forcing them to try and increase their signal strength.

Therefore, if you cannot achieve satisfactory results through playing with the router's location, choosing channels, or adjusting power, you should decrease the power and revisit the section above about covering rooms.

For metallic walls - apart from reducing the transmitter's power, you need to disable X Short GI (guard interval). And if available, lower the base rate in modulation settings (where you have rates like 6, 12, 24, 36, 48, and 54).

Regarding the power of radio bridges:
When setting up "on the table", set it to the minimum. Before installing, reduce the speed to the lowest, and adjust the power depending on distance. If the distance is long, opt for the maximum. However, under no circumstances should you direct devices close to one another; this can cause overheating or damage. After installation and proper antenna orientation, you can gradually increase the speed and decrease the power. The key is to make these adjustments smoothly. Otherwise, the connection might break, and you'll have to run to the other side with a laptop.

Standard channels

See also:

• IEEE 802.11
• Channel list
• WiFi roaming
• DFS.
• non-standard 802.11
• Long range WiFi
• OpenWRT
• Epic fail with TP-Link Deco mesh

FB