QCA wireless settings
From DD-WRT Wiki
This page shows the contents and descriptions of standard and advanced wireless settings for Qualcomm Atheros (QCA) based routers on the latest current wireless driver in use which is ath9k, & ath10k for 802.11ac. Not every router shows every possible setting shown here! Some routers will have less If you are a Broadcom or Ralink user, please refer to this page for Broadcom/Ralink wireless settings.
 Standard Settings
 Wireless Physical Interface
Available Interfaces: ath0, ath1 (Varies by router)
If you have a dual band router ath1 will be displayed below ath0 with the same available settings. Ath0 is the 2.4GHz radio and ath1 is the 5GHz radio for most routers, for some like the TL-WDR4900 v1.3, ath0 is 5GHz & ath1 is 2.4GHz its just the way the radios are connected on the PCB & is normal. If you create a VAP for 2.4GHz or 5GHz radio the VAPs will be labeled athX.1 & athX.1 respectively where X = the interface's number a VAP made on ath0 while be ath0.1 then 0.2 etc. Refer to this thread for some info about VAPs with Qualcomm Atheros.
 Wireless Mode
Available Settings: AP, Client, Client Bridge (Routed), AdHoc, WDS Station, WDS AP
Recommended Setting: AP for most users, other options if you are advanced and know you need it
Determines how the specific wireless interface of the router is to behave. If you want to run a normal access point which most do, AP would be your choice. Client and Client Bridge (Routed) is the Qualcomm Atheros equivalent to Broadcom's Repeater and Repeater Bridge modes.
 Wireless Network Mode
Available Settings (2.4 GHz): Disabled, Mixed, B-Only, G-Only, BG-Mixed, NG-Mixed, N-Only (2.4 GHz)
Available Settings (5 GHz): Disabled, A-Only N-Only (5 GHz), NA-Mixed, AC-Only, Mixed
Recommended Setting: What best suits you
Controls which 802.11 signals are being broadcast by the radio. Depending on the selected network mode your wireless channel list and maximum TX power can vary. Mixed is the recommended setting for most people as your clients' NICs are able to use either HT20, HT40, & HT80 "properly" with this setting. If you have any issues & hardly use or do not use 802.11b clients, switch to NG-Mixed. N-Only is broken on many units for some time & still is, try to avoid as there is NO performance change from Mixed -> NG-Mixed -> N-Only if all you use is 802.11n clients for either of them. For non-802.11ac 5 GHz radios, Mixed & NA-Mixed are theoretically the same.
 Channel Width
Available Settings: Dynamic (20/40 MHz), Wide HT80 (40+40 MHz)*, Wide HT40 (20+20 MHz), Full (20 MHz), Half (10 MHz), Quarter (5 MHz)
Recommended Setting: Wide HT80 (40+40 MHz)*, Wide HT40 (20+20 MHz), Full (20 MHz) if using long range (1km+) links or have interference in your area such as baby monitors, many other Wi-Fi APs etc.
This determines the width of the wireless channel where higher allows more bandwidth but less overlapping channels and lower allows more non-overlapping channels but less bandwidth. It is said that 40 MHz, which enables channel bonding by using two 20 MHz wide channels together, is not "neighbor friendly". This is correct as the wider channel creates more overlap onto other channels, which /could/ create more interference for neighbors, but usually is not an issue unless you are in a VERY packed wireless area. 40 MHz allows your 2.4GHz 802.11n draft devices to connect at their max of 300 Mbps when signal is sufficient as well as a large throughput increase and enables Atheros Super-G*. If Full (20 MHz) is used for 802.11n clients the max connection speed will only be 144 Mbps and 802.11g clients supporting Super-G max connection speed will only be 54 Mbps.
*Note: You MUST have this setting on Wide HT40 (20+20 MHz) to allow 802.11n devices (2.4 GHz & 5 GHz) to connect at their max!
*Note 2: 802.11g + Wide HT40 (20+20 MHz) = Super-G!*
*Note 3: Wide HT80 (40+40 MHz) is only displayed & available for 802.11ac (5 GHz) routers only & is required to reach the high PHY rates of 802.11ac
This is an Atheros technology to increase the throughput of 802.11g devices and NOT compatible with 40MHz channel width in 802.11n. In order to utilize the Super-G feature you must have an Atheros router capable of broadcasting 40 MHz wide channels, nearly all Atheros routers support this feature, and a Super-G ready client. If you have an Atheros router and Super-G ready client, ensure your wireless network mode is on Mixed or G-Only with Wide HT40 (20+20 MHz) as the channel width. The client should now connect at the theoretical max link rate of 108 Mbps, doubled that of standard 802.11g 54 Mbps. This feature reaches these speeds by channel bonding, a method that bonds two 20 MHz wide channels together, a similar way 802.11n does. Maximum true throughput with a Super-G client should be around 85 ~ 90 Mbps depending on distance, SNR, noise, & other wireless settings and optimizations.
 Wireless Channel
Available Settings (2.4 GHz): Channels 1 - 14 depending on your regulatory domain & channel width
Available Settings (5 GHz): Channels 34 - 64 (lower band), 100 - 140 (mid band), 149 - 165 (upper band) depending on your regulatory domain*
Recommended Setting: Any if on build r18000 or higher* Use the channel giving most throughput/range/SNR
Controls when channel or frequency your WLAN uses. If you have packet loss or abnormally slow throughput switch to another channel for less interference. All routers default to either channels 1, 6, or 11 (for 2.4 GHz), it is not recommended to use these channels as most users are inexperienced, and leave them at their defaults. Most of these channels are noisy but for any reason if there isn't many APs around you using these channels, use them.
- The reduced link rate issue with channels 1, 3, 5 appears to be corrected with the ath9k builds. As well as channel 11's weak TX power, could be Canada/USA's regulatory laws have changed also regarding channel 11 TX power.
- Available channels will vary greatly by region & there is no place on Earth where every 5 GHz channel is available legally. Only North America currently allows the upper 5 GHz band aka 5.8 GHz being channels 149-165, those channels allow high TX power up to 30 dBm, using a foreign regulatory setting to bypass your local laws is not recommended & is at your own risk.
 Extension Channel
Available Settings: Upper, lower, upper upper, lower lower*
Recommended Setting: Any
This setting is only valid when Wide HT40 (20+20 MHz) or Wide HT80 (40+40 MHz) is used for channel width. It controls the extension channel, which is the other channel(s) used to attain the 40 MHz width or in the case of 80 MHz for 802.11ac, the other 3 channels, is above or below the primary selected channel. Recent builds have fixed the selectable channels, use upper or lower depending which channel you want.
- Upper upper & lower lower are only listed for 802.11ac routers.
 Wireless Network Name (SSID)
This is where you can choose the name of your wireless network when its being broadcast to roaming clients. You can name this anything you want.
 Wireless SSID Broadcast
Available Settings: Enable, disable
Recommended Setting: Enable
Dependent on the setting above, this controls if your SSID is being broadcast or not. When disable is selected many clients still pick up the beacon and display it as "Hidden" along with the AP's MAC address. Disabling is not recommended as it hardly does anything for security, a determined intruder can still access your network with different methods.
 Advanced Settings
- Build 14815 and newer has a tab to show or hide advanced wireless settings.
 Regulatory Domain
This determines the channels available in the list for both bands (if you have a dual band router) and the maximum EIRP "legally" allowed by the telecom authorities in chosen country. EIRP is TX power plus antenna gain, an example.
20 dBm TX power and 2 dBi antenna gain has an EIRP of 22 dBm. 22 dBm TX power and 0 dBi antenna gain also has an EIRP of 22 dBm.
Maximum EIRP varies by nation and your max TX power will be capped by the regulatory domain if you have a powerful radio. For example, Canada's max EIRP is 36 dBm, with Canada selected and antenna gain at 0 dBi. The radios will never go above 36 dBm.
 TX Power
Recommended Setting: Highest dBm your radios/regulatory domain support
Transmit (TX) power is the amount of "current" or "juice" going to the antennas, it is NOT the output power FROM the antennas, as that is EIRP. Usually more TX power is better as it allows clients further away to "hear" your AP. Assuming the clients also have near equal TX power so the AP can "hear" them back. If TX power is increased too much excess noise can develop and reduce throughput or even range, this is an issue with most Broadcom routers. But with Qualcomm Atheros this does not seem to be much of a problem as most QCA radios work very well at their max TX power. Maximum TX power is controlled by the radios (power control*), regulatory domain, wireless channel used, & wireless channel width. The default value for most routers currently is 20 dBm.
An automatic feature which controls the max TX power by the SNR & link speed. The higher the SNR, the lower the TX power will be(this action does not display on the wireless status GUI). See vendor specs/FCC documents for more info.
 Antenna Gain
Recommended Setting: 0 dBi
Antenna gain is amount of "gain" or "boost" of signal that the antenna provides. Its a bit complicated but remember this, antennas are not amplifiers. They do not magnify the signal, but instead "focus" the signal in certain directions, yes even omni-directional antennas do it. The higher the gain the better as it increases EIRP which somewhat helps extend range and significantly helps sensitivity. With high sensitivity, the AP is able to hear "faint" clients, clients that may have a low TX power or are just simply very far away. Set this to 0 so DD-WRT does not take gain into consideration when calculating EIRP, depending on regulatory setting an example of 25 dBm EIRP(20 dBm TX power+5 dBi gain) may be too high when the limit is lets say 22 dBm, the TX power in this case will be forced down to 17 dBm. Antenna gain has no effect on performance of the WLAN directly.
 Protection Mode
Available Settings: None, CTS, RTS/CTS
Recommended Setting: RTS/CTS
This setting controls whether the clear to send/request to send mechanism is enabled or disabled. When enabled, a RTS/CTS handshake must be completed before data can be transmitted. Helpful in noisy environments it ensures all clients "take turns" communicating with the AP, if disabled sometimes packet collisions can occur causing a drop in throughput due to retransmission overhead. This is a setting to experiment with if you have high error rate or high noise floor (-90 noise is good, -60 is bad). Most users should leave this set to RTS/CTS for max throughput because the protection mechanism is only enabled automatically when needed, if its off when its needed, your wireless performance can plummet with errors, disconnects & low throughput, & if its no longer needed its turned off automatically on the fly. If you have 802.11b devices mixed with 802.11g/n then this setting is required to allow proper operation of 802.11b devices, if you have the hidden node problem this setting is also required to rectify it.
 RTS Threshold
Available Settings: Enable, Disable
Recommended Setting: Enable
Only valid if RTS/CTS is enabled, this setting sets the maximum packet size before it is fragmented into smaller packets, if you still have high TX/RX errors with RTS/CTS enabled and RTS Threshold at it's default, try lowering it by 10. Lowering it too much can further create overhead and reduce throughput. Leaving this on the default setting 2346 essentially disables the RTS feature and only leaves CTS enabled as most packets don't exceed 2346 bytes.
 Transmission Minimum & Maximum Rate
Available Settings: N/A
Recommended Setting: N/A
This setting has been removed for a while now due to it's lack of working function, its unknown if it will return. It controls the minimum and maximum theoretical rates for connected clients. It is recommended to leave this on Auto if you have the setting, or if it returns in future builds.
 Short Preamble
Available Settings: Enable, Disable
Recommended Setting: Enable
If you have 802.11b clients in your network try enabling this, if they have problems connecting or with performance then leave it disabled. Preamble is at the head or front of the PLCP which devices need in order to start transferring data. The long preamble ensure compatibility with legacy 802.11b devices but can slightly reduce throughput at high data rates. The support for short preamble which is reducing the header's size by 50%, down to 9 bytes, is optional for 802.11b. 802.11g and newer all support short preamble, so if you do not have 802.11b devices in your network leave this enabled at all times.
 TX & RX Antenna Chains
Available Settings: 1, 1+2, 1+3, 1+2+3
Recommended Setting: Varies by router
This setting is critical for proper, smooth, fast Wi-Fi performance. 2x2:2 routers will either have TX/RX chains at 1+2/1+2, 1+3/1+3, 1+2/1+3, or 1+3/1+2. This can take some time to find the proper setting but its worth it, you can more easily find the correct setting by using a 802.11n client thats capable of 300 Mbps link. Note the TX/RX link rates on the wireless status page, when set incorrectly one or both of the rates will drop to a much lower speed such as 200, 170, 81 etc. This is best done with the client less than 10 feet from the AP with clear line of sight. Some routers with chains set incorrectly such as D-Link DIR-615 C1, will deny connections to clients, heavily reduce throughput, and other errors. Searching the FCC ID of your router will aid in setting the correct chain settings. Some popular routers such as the Netgear WNDR3700 v1/2/4 and D-Link DIR-825 B1/B2 require both chains set at 1+2 for proper Wi-Fi performance. Default is not always right!*
*With recent builds (at least r20000+) most units have the proper defaults preset & invalid options removed, such as 1+2+3 for TX/RX on WNDR3700 as the router only has 2 chains each therefor only has 1 & 1+2 available to be selected.
 AP Isolation
Available Settings: Enable, Disable
Recommended Setting: Disable for private home Wi-Fi with trusted users, enable for public/guest Wi-Fi hotspot
AP Isolation allows clients connected to the same AP to communicate with each other or not, very much like Ad-Hoc mode. If you run a public Wi-Fi hotspot its recommended you enable this for privacy/security reasons & to help mitigate Wi-Fi snooping attacks that reveal login info such as this. If you want files to be shared from client to client in your home network, AP isolation must be disabled. This setting does not influence Wi-Fi throughput. If this setting is enabled it will break AdHoc based play on gaming devices such as Nintendo's DS system.
 Radar Detection
Available Settings: Enable, Disable
Recommended Setting: Disabled for most users. Enabled if country law requires it.
Radar Detection (DFS: Dynamic Frequency Selection). If enabled, radar detection will change the frequency only when it identifies a military or weather radar nearby in it's frequency. Most users shouldn't have any interference issues even those living near such locations. This applies to 5 GHz band only.
A list of channels to be used when searching, seperated by comma. Specially usefull when using SuperChannel feature. Leave this at the default value unless you know what it does.
 Sensitivity Range (ACK Timing)
Available Settings: 0 - 999999 (meters)
Recommended Setting: 0 - 900* for 2.4 GHz & 0 - 450 for 5 GHz, greater than 900 only when needed for long distance link
ACK timing is also a throughput controller, too high and your devices will literally be "waiting" too long and time will be passing with them at idle. Too low and active transmissions could be cut off causing retransmissions which create overhead, that lowers throughput. The AP sends a packet and all clients must wait for XXX time, where XXX is the ACK timing, the client then receives that packet and responds to the AP with an ACK(nowledgement), AP sees the AP then finally everyone is free to transmit.
Most users want this between 0 - 900/0 - 450 (2.4/5 GHz), the distance used is meters and needs to be doubled the distance of the furthest client from the AP (plus some headroom). Doubled because the signal travels to the client and back, double the distance. In earlier builds with the older MADWIFI driver reducing ACK from default 2000 to 1500 gave a throughput increase of 0.6 Mbps - 1 Mbps. Though with modern builds (r21061+) using the ath9k driver along with the internal changes to ACK timing, reducing to 1500 does little for throughput, one would have to drop at least below 1000m. With the current ath9k builds an ACK timing of 0 DOES disable it** completely like on Broadcom & gives a large 5-6 Mbps increase over default. But if you do not disable ACK timing remember ACK timing too low can cause issues such as cutting off a still in progress transmission, causing a retransmission that half way to the destination, clashes with the returning ACK of the first transmission. This usually only happens with hidden nodes &/or clients that are distanced very far away/beyond ACK timing's set range.
Long distance links, such as 2 KM+ will need to increase this setting accordingly. 4000m for 2km, 6000m for 3km, and so on, its good practice to add a little more 5-10% or so, than the exact needed value to account for any overhead etc.
- Current ath9k drivers only use ACK timing in 450m intervals, being 0, 450, 900, 1350, 1800 & so on. Setting a value such as 300m will automatically use the closest valid entry, being 450 in this case & you will see so on the wireless status page, setting 1300 will actually use 1350 & so on.
- 802.11g(n benefits too) mode with a DWA-542 NIC got 15 Mbps with default setting on a TL-WDR4900 v1.3, with ACK at 450 that rose to 20 Mbps, with ACK disabled it rose further to 21 Mbps & is consistently repeatable. As always your results will vary depending on router, channel, clients & interference. Users in heavy interference areas may benefit from leaving ACK timing on vs turning it off, disabled ACK timing is also known as the "No-Ack" setting in stock firmwares.
 Max Associated Clients
Available Settings: 1 - 256
Recommended Setting: What suits you
Determines the maximum number of clients that can be connected to the AP at any given time. Hotspot users will find this very handy. Using a shorter DHCP lease time such as 2 ~ 12 hours instead of default 24 will also help free up IPs if you are finding 256 users is not enough for a large public hotspot.
 MTik Compatibility
Available Settings: Enable, Disable
Recommended Setting: Disable
It activates a beta WDS compatibility with Mikrotik RouterOS. It's almost useless. Only use it when you're testing stuff from DD-WRT or using Mikrotik RouterOS.
 Network Configuration
Available Settings: Unbridged, Bridged
Recommended Setting: Bridged
This setting controls if the wireless interface is "bridged" with the LAN ports. Bridged meaning a client on the wireless interface and a client on the Ethernet LAN interface are on the same network on the same subnet. Unbridged allows you to "separate" the WLAN (wireless LAN) by giving it its own subnet and even its own DHCP server. If you want a unbridged interface, you are better off creating a VAP instead of unbridging the main interface.