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advanced-wireless

Advanced Wireless

The Advanced Wireless menu contains settings for advanced tuning of WiFi interfaces. Changing settings from defaults is not recommended unless you are experienced with advanced WiFi settings. Default dropdown settings are noted with an asterisk (*). For basic WiFi settings, see the the Network menu wiki page.




Afterburner

(Note: only supported on MIPS RT & RT-N branch/images, NOT ARM)

Enabling Afterburner turns on support for Broadcom's frame-bursting and compression technology to improve 802.11g wireless throughput. This feature is also known as 125 High Speed Mode (or 125HSM) and goes by other names with other hardware vendors. Theoretically, this boosts signalling rates to 125 MB/s. Realistically, one can expect 30-40 Mb/s throughput in real world environments. Since this is a proprietary protocol extension, effectiveness will vary depending on the client device maker as well.


  • Disable *
  • Enable
  • Auto


Authentication Type

This option controls whether clients must use shared keys to authenticate. Shared Key is disabled in some wireless security modes, for compatibility reasons.


  • Auto *
  • Shared Key


Protected Management Frames

(Default: Off).

Protected Management Frames (PMF), or Management Frame Protection (MFP). Support for this (ARM-only) option started with release 2021.6.

  • Disable * - Choosing this turns off PMF.
  • Capable - This allows all WiFi clients to connect to the network, whether or not they're PMF-capable.
    Check your wireless clients for connectivity problems.
  • Required - Only PMF-capable WiFi clients can connect to the network.


Protected Management Frames (PMF) provide security for unicast and multicast management action frames. PMF prevents unicast management action frames from eavesdropping and forging. It also prevents forged multicast management action frames. PMF augments existing privacy protections for data frames with mechanisms that improve the resilience of mission-critical networks.

By default, this feature is disabled because not all wireless clients support it.


Basic Rate

The Basic Rate Set is a list of rates at which the router reports it can sync. with wireless client devices. A router regularly broadcasts the Basic Rate Set in its beacon packets. In this way, wireless clients in your network know which rates will be used. The Router will also advertise that it will automatically select the best rate for transmission.


  • Default *
  • 1-2 Mbps
  • All


Default: Tomato advertises it can sync. at all standard wireless rates, including 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, and 802.11b rates of 1, 2, 5.5 and 11 Mbps.

1-2 Mbps: This setting is sometimes required for compatibility with 802.11b clients, if they don't connect via the Default setting.

All: This setting makes Tomato advertise all wireless rates supported in hardware.

:pasted:20220309-082608.png


Beacon Interval

(Default: 100 ms).

This specifies the time period between one beacon broadcast and the next. A beacon is a packet broadcast by the router to synchronize the wireless network and serve administrative functions. Beacons typically include information such as the SSID, Timestamp, various parameters and the router's available services.

Beacons use up some network bandwidth that could be used for transmission of actual user data. Therefore, using a higher value (more time between beacon broadcasts) may achieve better throughput on your network.

Using higher beacon values may also extend the battery life of some mobile client devices. This is because WiFi adapters are able to “sleep” in between beacon broadcasts. When beacons are less frequent, your devices have more time to sleep, saving energy in the process. Thus, battery life increases.

Setting a lower beacon interval allows faster router discovery. When the router sends beacons more frequently, clients can discover it more quickly. This can help with weak signals and poor reception environments. After all, the more frequenlty beacons are sent, the better the chance client devices will receive them. This can also be helpful when you are using roaming features, with multiple APs. It allows the client devices to better choose which AP to connect to.


CTS Protection Mode


  • Disable *
  • Auto - Determines which computer can reach the router at a specific time
    through CTS and its send (RTS) packet.


This function could more appropriately be called RTS/CTS Protection Mode. Wireless client devices transmitting to a router cannot detect when other devices on the same network are also transmitting. When more than one client transmits at a time, data collisions occur. The router is then forced to discard data from both clients. This increases error rates and reduces speed.

When Clear-to-Send Protection is on, a computer must send a RTS (Request to Send) frame to the router. This is basically a request to be allowed to transmit at that moment. In return, the router must send back a Clear-To-Send frame indicating the client can send data. In this way, CTS Protection Mode determines the order in which computers contact the access router. Typically, CTS frames are not needed until the client has a data frame to send that meets a size threshold. That threshold frame size can be set in the RTS Threshold field. See below for details.

CTS is typically used for 802.11b/g/n/ac protocols. RTS-CTS is typically used with 802.11a/b/g protocols.

Disable is the recommended setting, as well-designed networks rarely need it. However, if you experience lots of physical layer collisions, try enabling this and tuning the RTS Threshold setting.


Regulatory Mode

This option lets you choose which wireless standards are followed.


  • Off *
  • 802.11d
  • 802.11h


Countries which share a common set of regulations are called regulatory domains in the 802.11 specification. Four major regulatory bodies have authority over almost all of the world's technology regulations:


  1. Federal Communications Commission or “FCC” (USA)
  2. European Telecommunications Standards Institute or “ETSI”
  3. Telecom Engineering Center or “TELEC” (Japan)
  4. (South) Korea Communications Commission (KCC)


Each domain has strict regulations for parameters like antenna gain, transmit power, channel selection. Many countries adhere to the standards completely. A few countries modify an existing standard to their unique needs. This can create complications.

802.11d: This supplemental standard adds requirements and definitions necessary to allow 802.11 equipment to operate in markets not served by the current standard. This includes anywhere outside the Americas (FCC), Europe (ETSI), Japan (TELEC), China, Israel, Singapore, and Taiwan.[1]

802.11h: 802.11h is the standard for Spectrum and Transmit Power Management Extensions. It solves problems like interference with satellites and radar using the same 5 GHz frequency band. The standard provides Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to the IEEE 802.11a MAC layer.


Country / Region

(Default: Singapore / 12) [ARM]

The Country / Region AND Country Rev(ision) codes define the possible channel list, power and other regulations for each country. The current wireless driver (year 2020 and newer) supports approximately 290 countries and 2000 combinations of country code and revision.

Please See: Country Code / Country Rev Collection for FreshTomato


:pasted:20220309-082745.png


Some Country / Rev combinations are invalid, and don't work together.

For example, on ARM routers, setting Country to USA by just changing Country to “US” and leaving Revision set to “12” is invalid. You need to change Country / Region to “US” and revision to “0” for a valid combination. Using an invalid combination can cause problems with WiFi functioning.


SDK6 Example Country / Region and Country Rev choices (ARM Routers):

  • EU / 13 - Country: EU (Europe) AND Country Rev: 13 (Asus defaults for Germany and SDK6 routers: RT-N18U, RT-AC56U, RT-AC68U C1)
  • EU / 13 - Country: EU (Europe) AND Country Rev: 13 (Asus defaults for Germany and SDK6 routers: RT-N18U, RT-AC56U, RT-AC68U C1)
  • EU / 13 - Country: EU (Europe) AND Country Rev: 13 (Asus defaults for UK [alias “EU”] and SDK6 routers: RT-AC68U C1 - Bought in: UK)
  • EU / 33 - Country: EU (Europe) AND Country Rev: 33 (Asus defaults for Germany and SDK6 router: RT-AC66U_B1)
  • US / 0 - Country: US (USA) AND Country Rev: 0 (Asus defaults for USA and SDK6 routers: RT-AC68U A1/A2)
  • US / 0 - Country: US (USA) AND Country Rev: 0 (Asus defaults for Canada and SDK6 router: RT-AC68U A2 - Bought in: Canada)
  • US / 10 - Country: US (USA) AND Country Rev: 10 (Asus defaulst for USA and SDK6 router: RT-AC56U - Bought in: USA [CFE: 1.0.2.7])
  • Q2 / 33 - Country: Q2 (USA) AND Country Rev: 33 (Asus defaults for USA and SDK6 router: RT-AC68U C1)
  • Q2 / 40 - Country: Q2 (USA) AND Country Rev: 40 (Asus defaults for USA and SDK6 router: RT-AC68U B1/B2)
  • Q2 / 61 - Country: Q2 (USA) AND Country Rev: 61 (Asus defaults for USA and SDK6 router: RT-AC66U_B1 / RT-AC1750_B1)
  • CA / 58 - Country: CA (Canada) AND Country Rev: 58 (Asus defaults for Canada and SDK6 router: RT-AC1900P)
  • SG / 12 - Country: SG (Singapore) AND Country Rev: 12 (default *)


SDK7 Example Country / Region and Country Rev choices (ARM Routers):

  • E0 / 989 - Country: E0 AND Country Rev: 989 (Asus default setup for UK [alias “E0”] and SDK7 router RT-AC3200 - Bought in: UK)
  • Q2 / 96 - Country: Q2 (USA) AND Country Rev: 96 (Asus default setup for USA and SDK7 router RT-AC3200)
  • SG / 12 - Country: SG (Singapore) AND Country Rev: 12 (Default *)


SDK714 Example Country / Region and Country Rev choices (ARM Routers):

  • E0 / 946 - Country: E0 AND Country Rev: 946 (Asus default setup for Germany [alias “E0”] and SDK714 router RT-AC5300)
  • Q2 / 992 - Country: Q2 AND Country Rev: 992 (Asus default setup for USA [alias “Q2”] and SDK714 router RT-AC3100)
  • Q1 / 984 - Country: Q1 AND Country Rev: 984 (Asus default setup for USA [alias “Q1”] and SDK714 router RT-AC5300)
  • TBD. - CFE default value used


Example Country / Region and Country Rev choices (MIPS Routers, RT-N and RT-AC):

  • EU / 4 - Country: EU (Europe) AND Country Rev: 4
  • EU / 13 - Country: EU (Europe) AND Country Rev: 13
  • PL / 2 - Country: PL (Poland) AND Country Rev: 2
  • DE / 3 - Country: DE (Germany) AND Country Rev: 3
  • US / 10 - Country: US (USA) AND Country Rev: 10
  • CN / 1 - Country: CN (China) AND Country Rev: 1
  • TW / 4 - Country: TW (Taiwan) AND Country Rev: 4


Advanced users can see the complete list of settings and their code commit entries here:


SDK6 ARM routers:
https://bitbucket.org/pedro311/freshtomato-arm/commits/ffb286c7afa64b02bc2136d6bd67ba6f7f6b42b2


SDK7 ARM routers:
https://bitbucket.org/pedro311/freshtomato-arm/commits/92da4ad49c2df3bc6d17f58c1b564891ce87a048


SDK714 ARM routers: Not yet available.


SDK5 Mips (RT-N) routers:
https://bitbucket.org/pedro311/freshtomato-mips/commits/5c72e2e4753e2e2db86c519fa5d89f18ee555aff

MIPS SDK5 (RT) builds, there is only a Country setting.


SDK6 MIPS (RT-AC) routers:
https://bitbucket.org/pedro311/freshtomato-mips/commits/65128b4b2de5c677349dcbd7fe018e23e45c8bba


For example: for SDK6 (ARM models/builds) and country: USA, open file “wlc_clm_data.c” in directory:
“sysdeps/RT-AC68U/clm/src/wlc_clm_data.c” and go to line ~98738. You should see the following:

/** Region definitions */
static const clm_country_rev_definition10_fl_t country_definitions[] = {
    /*      CC    rev      2.4        5            2.4 HT              5 HT  flags */
...
...
    REGION("US", 0 /*  0 */,   A6_58,   29e_2,           An7_62,           29en_9, SCR_2    | CLM_DATA_FLAG_REG_TXBF), /* US/0 */  <-- Line:  98738 (Example provided at advanced-wireless page)
    REGION("US", 1 /*  1 */,   A6_58,   29e_2,           An7_62,           29en_9, SCR_2    | CLM_DATA_FLAG_REG_TXBF), /* US/1 */
    REGION("US", 2 /* 11 */,      A1,     19b,              An4,             19bn, SCR_NONE), /* US/11 */
    REGION("US", 3 /* 13 */,      A5,      15,              An6,              15n, SCR_NONE), /* US/13 */
    REGION("US", 4 /* 14 */,      A6,      15,              An7,              15n, SCR_NONE), /* US/14 */
    REGION("US", 5 /* 18 */,      A9,      15,            An6_2,              15n, SCR_NONE), /* US/18 */
    REGION("US", 6 /* 19 */,      A6,      19,           An8_T2,             19cn, SCR_NONE), /* US/19 */
    REGION("US", 7 /* 20 */,      A3,    19_1,           An1_T3,            19n_1, SCR_NONE), /* US/20 */
...
...



The comment field on the right contains valid Country / Revision combinations. Notice that Country: “US” and Country Rev: “12” is NOT a valid setting for the WiFi driver. Do not use “#a” or “#r”. These are special values designed only for testing purposes.


Starting with MIPS SDK6 (RT-AC) builds and all ARM Branches/Versions you must choose a Country and a Country Revision. This applies to releases 2020.6 and later. With release 2022.4 and later, you will need to choose a Country and Revison code for RT-N models also.


Note for Asus models: To check the Country / Revision combination stored in the bootloader (the factory default value), use the following system commands.


For example, on an RT-AC66U_B1 ARM router:


root@RT-AC66U_B1:/tmp/home/root# cat /dev/mtd0ro | grep ccode
0:ccode=EU
1:ccode=EU
root@RT-AC66U_B1:/tmp/home/root# cat /dev/mtd0ro | grep regrev
0:regrev=33
1:regrev=33
root@RT-AC66U_B1:/tmp/home/root#


On some older routers, some combinations may no longer be supported by the WiFi driver. For example, see: example.


To check the current wireless country setup:


root@R7000:/tmp/home/root# wl -i eth1 country
DE (DE/7) GERMANY
root@R7000:/tmp/home/root# wl -i eth2 country
DE (DE/7) GERMANY
root@R7000:/tmp/home/root#


Country Revision

For an explanation of this setting, see the Country/Region section above. The Revision setting exists only in releases 2020.6 and later. On MIPS SDK5 (RT-N) models, the setting exists starting with release 2022.4.


Bluetooth Coexistence


  • Disable *
  • Enable
  • Preemption


 :pasted:20220309-082841.png


Bluetooth and 2.4 GHz WiFi radio waves can interfere with each other, since both operate on the same band. Choosing Enable can help to reduce that interference, by asking the Bluetooth devices to take turns using the same channels as your WiFi.

The Preemptive function will make FreshTomato inform the Bluetooth device about which Bluetooth channel it's operating on. The Bluetooth device can then mark that channel as “in use” and use alternate channels for its own communications.

The Bluetooth devices must support the Bluetooth Coexistence function, or they will be unable to share nicely and this option will have no effect.

This option is available only on the 2.4GHz interface.


Distance / ACK Timing

(Default: 0)

When a router sends a packet to a client, it waits for an ACKnowledgement frame from the client to ensure the packet was received. The time period the router waits for that acknowledgement is called the “ACK timeout” (or “Timing”). Traditionally, ACK Timing is set to the maximum distance of the furthest client device in meters x 2. The doubling is to account for the round-trip distance/time, including the time it takes for the client to receive the packet, and the time for the response to travel back to the router. For example, if you roam with your laptop up to 50 meters from your AP, the setting would be 100. Generally, the default is recommended, except where administrators have a strong knowledge of timing or are building long-distance wireless links.

Typically, 802.11b/g has a range of less than 100 meters. Therefore, one might assume this should never be set higher than 200. However, in scenarios with high power antennas or other long-range gear, the timing settings would need to increase. Longer distance links have been established far beyond the theoretical limits of 802.11 b/g.

However, higher ACK Timing comes at the cost of lower throughput. If set too high, packets could be lost as the router waits for the ACK window to timeout for ACK frames that were never going to arrive. It will also resend the “unacknowledged” packet to the client, thinking it might not have received it yet. If ACK Timing is too low, the router may drop returning ACK frames too early, and again resend the original “unacknowledged” packet. This too might lower throughput.


Roaming Assistant

(Default: 0 / Disabled)

This function allows you “kick” users with a weak signal signal strength at or below at value you set, off the WiFi network. After enabling the Roaming Assistant, you can define the value for disconnecting clients with RSSI lower than -XY dBm (Valid range: -90 to -45) from your WiFi radio interface (eth1/eth2/eth3).

Support for this option started with release 2022.1 (ARM & MIPS hardware; Some MIPS models may not include this setting).


DTIM Interval

(Default: 1)

A Delivery Traffic Indication Message (DTIM) message is a field included in some beacon frames. It informs clients that the access point/router has buffered or multicast/broadcast data to receive. When in power-save mode, a client device may sleep for one or more beacon intervals, then wake up for beacon frames that include DTIMs. A DTIM message notifies sleeping clients that they will need to wake up to receive the waiting frames.

The DTIM Interval specifies how often a beacon frame includes a DTIM message, expressed as the number of beacon frames that will be sent before a DTIM is included in a beacon frame. DTIM Interval values range 1 to 255. The DTIM Interval value is included in each beacon frame. Following a beacon frame that includes a DTIM, the router will release any existing buffered broadcast and/or multicast data. This means that the DTIM message is included in every second beacon frame.

  • Shorter DTIM Intervals force network clients to wake up more often to be ready to receive broadcast/multicast traffic. This puts higher loads on the clients, which may increase power consumption, which may cause battery-powered devices to drain faster.
  • Longer DTIM Intervals let clients sleep longer and save power. However, with the router waiting to send the data, it may have to buffer more of the broadcast/multicast data. The extra buffering could cause overruns if the router can't store all the data until it can be sent. Thus, longer intervals can slow throughput.


In short, WiFi clients may have conflicting requirements for power consumption and communication throughput when in power-save mode.


Fragmentation Threshold

(Default: 2346)

IP fragmentation occurs when the IP layer breaks down datagrams into smaller pieces (fragments). The destination host, or sometimes intermediate routers reassemble the fragments to make the message whole again. This is usually done to reduce the size of the datagrams so the pieces can pass through a link with a smaller MTU than the original datagram size.

This option specifies the maximum size of datagram that can occur before it's fragmented into multiple datagrams. Similar to RTS Threshold, tuning Fragmentation Threshold may reduce frequent collisions on the network. Too low values may cause poor network performance. The default setting is recommended.



Frame Burst


  • Disabled *
  • Enabled


Frame-bursting is a link layer protocol used to increase the throughput of connections on links between 802.11a/b/g/n hosts under certain network conditions. It does this by reducing the overhead used in the wireless session between hosts. It grew from standards first introduced in the 802.11e QoS specification for link layer connections.

Network protocols for shared media are designed so that any host that has sent a MAC layer frame is then supposed to yield the medium and wait for a fixed period of time. This helps create a fair use of the medium by multiple users.

Frame bursting allows wireless clients to upload data at faster speeds by using the wait intervals between frames to “burst” a series of up to three frames before waiting the required period. As usual, there are compromises. Frame Burst can cause unfair allocation of airtime on networks where where only some clients support Frame Burst. The wait periods between frames were not originally designed to include data traffic. The recommended setting is Disabled, unless there are very few hosts on your network. Broadcom's implementation of this feature is called “Express Technology”.



Maximum Clients

(Default: 128)

This specifies the maximum number of clients that can be connected to the WiFi network. It is not reccomended to increase this number, as the likely result will be an overloaded network with slow throughput. There is little harm in testing a lower number. This can be useful to reduce network traffic, or for security purposes.


Multicast Rate


  • Auto *
  • 1 Mbps
  • … up to
  • 54 Mbps


This setting controls the rate at which hosts can send multicast packets to a multicast group. Traffic exceeding this rate is discarded. Optimizing this rate can lower collisions, especially when multiple devices or services are being run at the same time. Optimization may be essential for applications which stream video and corporate communications.

For small, basic networks, the default should work fine. However, on larger networks, it's recommended that you adjust this setting. Typically, switching to the lowest setting is the quickest, easiest way to optimize your system. However, networks with more client devices will likely require higher settings to be effective. Setting this too high can impact performance, so you may need to test to ensure that your setting isn’t using up all of the bandwidth on just one device.


Preamble


  • Long *
  • Short


In wireless networking, the preamble (or “header”) is a section of data at the head of data link layer frames which contains information wireless devices need to send and receive data. Part of the preamble involves the length of the CRC (Cyclic Redundancy Check) block for communication between the router/AP and roaming wireless adapters. CRC is commonly used to detect data transmission errors.

Generally, all WiFi devices on the LAN should use the same preamble type. If they don't, they will have trouble communicating. On some legacy wireless equipment, Preamble type may bet set with a physical switch. In current hardware, it is set via the web interface or command-line interface.

The default setting is Long, to maintain compatibility with older equipment. Long preamble is also recommended for long-distance connections or links with weak signals, since both require more extensive error checking. The Short preamble can be used on modern gear which transmits strong signals in a low-interference environment.


802.11n Preamble


  • Auto
  • Mixed Mode *
  • Greenfield
  • GF-BRCM


For an explanation of wireless preamble basics, see the Preamble section above.

Auto: TBD.

Mixed Mode: Mixed Mode transmissions can be decoded by 802.11a/g clients, for backwards compatibility. In Mixed mode, 802.11n devices transmit a legacy format preamble, followed by an HT format preamble and a legacy radio signal. A Mixed mode device must also send legacy format CTS-to-Self or RTS/CTS (Request to Send/Clear to Send) frames before transmitting. These mechanisms let other 802.11a/b/g devices sense a busy network medium and wait for another turn to transmit. This allows backwards compatibility with earlier protocols, but reduces throughput, compared with Greenfield, or GF-BRCM modes.

Greenfield: This 802.11n mode is also known as “High Throughput” mode. In this mode, 802.11n improves efficiency by using a high throughput modulation method and a shorter preamble. Neither feature is supported on 802.11a/b/g devices. This preamble mode breaks backwards compatibility and can reduce throughput on some 802.11n devices not fully Greenfield-compatible. See the explanation of GF-BRCM below for a possible solution to such problems.

GF-BRCM: “Greenfield-Broadcom” is the Broadcom proprietary pre- or draft-802.11n implementation of Greenfield. Choosing this option may prevent problems with devices which are not fully Greenfield compliant.


Overlapping BSS Coexistence


  • Off * Channel width settings will function as configured.
  • On: If FreshTomato detects interference, it will switch from use of 40 MHz channel width to 20MHz channel width.



Overlapping BSS Coexistence is a feature to help prevent interference between WiFi networks. When you enable Overlapping BSS Coexistence, your router’s 2.4 GHz radio will use a 40 MHz channel (if it's configured that way) until it detects another router or AP using a 40 MHz channel width. When this happens, your router will fall back to using a 20 MHz channel to avoid interference with the “nearby” network(s).

Depending on your network, disabling Overlapping BSS Coexistence might help your devices connect to the WiFi router at faster speeds.


RTS Threshold

(Default: 2347)

When CTS (Clear-to-Send) Protection is on, a host must send an RTS (Request-to-Send) frame to the router to get permission to transmit data frames at that time. In return, the router must send back a Clear-To-Send frame, indicating the client can send data. In this way, CTS Protection Mode determines the order in which computers contact the router. Typically, CTS frames aren't needed until the client has a data frame to send that meets a size threshold. The RTS Threshold is that threshold frame size.


Transmit Power

(Default: 0)

This lets you override regulatory and other limitations to increase or lower the Transmit Power, in milliwatts. The default setting of “0” uses the regulated power level for your chosen Country setting. Before you increase Transmit Power to improve signal range, you are advised to try signal-reception solutions first, such as relocating your router to a more central location, elevating it, or using higher gain, external antennas.

Lowering Transmit Power can be useful for increasing security. For example, if power is too low to reach past the boundaries of your property, it will be harder for others outside your property to snoop on your connection. Lowering Transmit Power can also reduce interference received by other, nearby radio equipment.


Transmission Rate

The Transmission Rate is the rate at which data are being transerred between a router and a WiFi client device. Several factors affect Transmission Rate, including the WiFi protocol used, signal strength, channel width (in MHz), and the use of MIMO or SU-MIMO. This setting is outdated and mostly applies to older protocols such as 802.11g. In general, you are advised to leave the setting on Auto.


  • Auto * (Default)
  • 1 Mbps
  • … up to
  • 54 Mbps


AC-PHY Interference Mitigation

This option is only available for wireless chipsets/ICs which support the 802.11ac protocol.


  • None * (default)
  • desense based on glitch count (opt. 1)
  • limit pktgain based on hwaci (opt. 2)
  • limit pktgain based on w2/nb (opt. 3)
  • opt. 1 AND opt. 2
  • opt. 1 AND opt. 3
  • opt. 2 AND opt. 3
  • opt. 1 AND opt. 2 AND opt. 3 (All option enabled)

When Access Points/routers within radio range of each other are administered separately, their configured channels might overlap. Since AP's operate in an unregulated ISM frequency band, there also may be other equipment operating on or near the same ferquencies, such as microwave ovens, Bluetooth gear, or wireless keyboards and mice.

Starting with with WiFi protocol 802.11ac, AC-PHY Interference Mitigation mechanisms can use 3 different strategies, or combinations of them, to reduce interference from other “nearby” devices . Depending of which WiFi chipset/radio your router contains,





Interference Mitigation (non-802.11ac)

This sets the Wireless Interference Mitigation mode. This option is only available wireless chipsets/interfaces that do NOT support 802.11ac. For chipsets that support 802.11ac, please see the section titled “AC-PHY Interference Mitigation”.


  • None * (Default)
  • Non-WLAN
  • WLAN Manual
  • WLAN Auto
  • WLAN Auto with Noise Reduction


None: This setting is recommended if there are no other “nearby” electronic devices that may cause interference.

Non-WLAN: Use this if the main source of your interference is non-Wireless LAN devices, such as cordless phones, microwaves and so on.

WLAN Manual: This activates interference mitigation against other Wireless LAN Access Points.

WLAN Auto: Similar to WLAN Manual, this activates mitigation only if FreshTomato detects other APs transmitting at the same time. This seems to work better in most cases, but consider disabling it if you get WiFi stability issues. It has been known to cause instability and poor throughput.

WLAN Auto with Noise Reduction:


WMM


  • Auto
  • Disable
  • Enable * (Default / recommended)


Wireless MultiMedia is a best-effort form of QoS that maintains the priority of audio, video and voice applications over others which are less time critical. WMM ensures that applications that need better throughput and performance are inserted with a higher position in priority queues.

For example, video and audio applications would get higher priority over a file transfer application. Setting priorities this way would prevent the parties in a (VoIP) phone conversation from experiencing delays, as the network would ensure packets arrive on time. Someone watching a video would be more likely to see smooth action.

However, WMM can be very data demanding. With older WiFi protocols, such as (802.11b, a, g ) it may use too much bandwidth. For this reason, you can disable it to free up usable bandwidth.

However, WMM is a requirement of the 802.11n, 802.11ac and 802.11ax specifications. Disabling it will cause fully WMM-compliant clients to fall back to 802.11a/g legacy rates (of 54 Megabits/second).

Also note that if you some Apple products, such as iPhone, iPad, iPod touch, or Apple TV may not be able to connect to WiFi via the 802.1 protocl unless WMM is enabled.

No ACK

ACKnowledgement frames are sent on networks to acknowledge receipt of data frames. This allows applicable protocols to guarantee data delivery. However, it can also slow throughput. If your network is reliable enough without acknowledgements, disabling them may improve throughput. Caution is advised before enabling this setting.


  • Enable
  • Disable * (Default)


APSD Mode

Automatic Power Save Delivery options:


  • Disable
  • Enable * (Default)


When your client device's WiFi adapter enters into power saving mode or “sleep” mode, FreshTomato can buffer data and hold it for your mobile devices with the WMM APSD function. This can help to save power, which is especially important for battery-powered devices. This feature can also reduce the latency of traffic flow to/from WiFi clients.

There are two types of APSD power saving features. with U-APSD (Unscheduled Automatic Power Save Delivery), your client devices signal the router to transmit any buffered data.

With S-APSD (Scheduled Automatic Power Save Delivery), the router sends buffered data on a fixed schedule known to the power-saving device without any signal from the client device.


Wireless Multicast Forwarding


  • Disable * (default)
  • Enable



Modulation Scheme

(Note: was called Turbo QAM up to 2022.7)

This setting will enable Turbo QAM, Broadcom's name for 256-QAM. Do not confuse this with Broadcom's other Turbo QAM, a modulation scheme used for cablemodem technology. (Requires Wireless Network Mode set to Auto)

Turbo QAM, or 256-QAM is a modulation method in which the two carrier signals are shifted in phase by 90 degrees. These two signals are then modulated and combined. The 90° difference in phase between the two signals means they are “in quadrature”.

In theory, this modulation method makes it possible to transmit more bits per symbol, and thus increase data rates. In reality, most claims of big increases in transfer rates are likely exaggerated. QAM links are more susceptible to noise. As a result, Turbo QAM is generally only useful in very low-noise/interference wireless environments. Many people report it being effective on line-of-sight links of up to about 25 feet. Vendors claim the range with Turbo QAM may improve when beamforming is used. You may need to experiment to see what works best on your network.

NitroQAM/1024-QAM is only available for SDK714 Routers like the RT-AC5300, RT-AC3100 or RT-AC88U.





Explicit beamforming

Checking this enables Explicit beamforming technology. Traditionally, most WiFi routers and access points have included omnidirectional antennas. These radiate radio energy equally in all directions. This is not always the most effective/efficient way to exchange radio signals with a client device. Much of the signal goes off in directions other than the client or other device. Explicit beamforming improves on this.

Beamforming radiates signals towards the receiver, instead of in an omnidirectional pattern. If the hardware has adequate information to send the radio energy in one particular direction, it will do so. The result can be an increase the signal-to-noise ratio and data rates between the two devices.

Beamforming was introduced starting with 802.11n. but vendors used different standards. This meant beamforming made little difference in performance. With 802.11ac, the beamforming method was standardized (Explicit). Compatibility across vendors is good. Explicit beamforming requires both client and router/Access point to support the feature. If both devices support it, they'll use a handshake at the beginning of their session to help establish their respective locations and the channel on which they'll communicate.

Beamforming works best at medium range. At short range, the signal power is high enough that the signal-to-noise ratio will support the maximum data rate. At long ranges, beamforming does not offer gains over an omnidirectional antenna.


Universal/Implicit beamforming

Beamforming is a performance feature included in WiFi protocols starting with 802.11n. Beamforming radiates signals more directly towards the receiver, instead of in an omnidirectional pattern, like older equipment. This can result in a higher signal-to-noise ratio and faster data rates between the two devices exchanging data.

Traditionally, most WiFi routers and access points included omnidirectional antennas. These radiate radio energy equally in all directions. This is not the most effective/efficient way to exchange radio signals to another device. Much of the signal goes off in directions away from the or other wireless device.

With 802.11n, several beamforming methods were allowed, but no standard method existed. A lack of standardization meant beamforming usually provided little performance improvement.

Implicit beamforming is used with legacy devices that don't support beamforming. With Implicit beamforming, the router estimates the channel and determines the radiation direction to improve signal/transmission rate to the client device. However, it won't be able to radiate signal as precisely to the endpoint device as it could if the endpoint supported Explicit beamforming. (See above section). Implicit beamforming is also known as Universal beamforming, since it can theoretically work with almost all client equipment, even that which doesn't support beamforming.

Both access points and clients (which support it) can use beamforming. However, the higher processing power and larger distance between antennas in routers/access points means that most beamforming performance gains should be expected in transmissions from router/AP to client.


Optimized for Xbox


  • Disable * (Default will enable LDPC (Low-Density-Parity-Check) cap.)
  • Enable


LDPC is a forward error correction capability that allows single bit errors to be automatically corrected. Starting with 802.11n, LDPC was added as an optional capability that must be negotiated as part of the 802.11 association process. If LDPC is enabled, an AP will advertise that capability in its beacon packets.

LDPC can increase signal-to-noise ratio, (SNR) approximately 1-2 dB, depending on specifics of the channel being used. When LDCP increases SNR, it can consequently improve data rates, and in doing so, reduce airtime utilization.

Enabling Optimized for Xbox disables LDPC.

Note: Align Option/Label name to AsusWRT (see commit)


Air Time Fairness

Generally, the relationship between Wifi (clients) and a broadcaster is generally first-come first-serve. Moreover, many broadcasters might take the slowest client's speed as the effective rate of all connected clients on the same band.

advanced-wireless.txt · Last modified: 2023/10/13 10:59 by m_ars