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wireless

Advanced Wireless

The Advanced Wireless menu contains settings for advanced tuning of Wi-Fi interfaces. It is not recommended you change these settings from the defaults unless you are knowledgeable about and experienced with advanced Wi-Fi settings. All default settings in dropdown menus on this page are noted with an asterisk (*).

Afterburner

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.

Options:

  • Disable * (Default)
  • Enable
  • Auto

AP Isolation

When enabled, wireless clients will not be able to communicate with each other through the FreshTomato router, but will be able to communicate with the router itself or to the Internet. This may be useful on guest networks, to prevent hacking and other security problems. This doesn't guarantee security, however. For example, this setting does NOT prevent ad hoc Wi-Fi connections between client devices, or direct Bluetooth or NFC connections.

Options:

  • Disable * (Default)
  • Enable

Authentication Type

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

Options:

  • Auto * (Default)
  • Shared Key

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.

Options:

  • Default *
  • 1-2 Mbps
  • All

Default: The router advertises that it can sync. at all standard wireless rates. This includes: 6, 9, 12, 18, 24, 36, 48, and 54 Mbps in addition to the 802.11b rates of 1, 2, 5.5 and 11Mbps.

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

All: This setting makes the router advertise all wireless rates supported by its hardware.

wiki.freshtomato.org_lib_plugins_ckgedit_fckeditor_userfiles_image_advancedwirelessnosidebar.jpg

Beacon Interval

This setting specifies the period of time between one beacon broadcast and the next. A beacon is a packet broadcast by the router to synchronize the wireless network and serve other administrative functions. (Default: 100 ms).

CTS Protection Mode

Options:

  • Disable * (Default)
  • Auto

This function could more appropriately be called RTS/CTS Protection Mode. Wireless client devices transmitting to an 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 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 access point/router. Typically, CTS frames are not sent/needed until the client has a data frame to send that meets a certain size threshold. That threshold frame size can be set in the RTS Threshold field. See below for details about that setting. CTS is typically used for 802.11b/g/n/ac protocols. RTS-CTS is typically used with 802.11a/b/g protocols.

Auto: determines which computer can reach the FreshTomato router at a specific time through CTS and its send (RTS) packet. Disabled is the recommended setting, since well-designed networks rarely need it. However, if you are experiencing lots of physical layer collisions, then you might try enabling this and tuning the RTS Threshold setting.

Regulatory Mode

This menu lets you choose which wireless standards are followed. Countries (usually adjoining) that share a common set of regulations are referred to in the 802.11 specification as regulatory domains. 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 such as antenna gain, transmit power, channel selection which must be adhered to. Many countries choose to adhere to the standards completely. A few countries use one standard as a guideline and modify it to their own unique needs. This can create complications and compatibility issues.

Options:

  • Off * (Default)
  • 802.11d
  • 802.11h

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

802.11h: 802.11h is the IEEE 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. (Media Access Control layer).

Country / Region

Country code AND rev(ision) 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.

Example Country / Region and Country Rev choices:

  • CY / 4 - Country: CY (Cyprus) AND Country Rev: 4
  • CZ / 4 - Country: CZ (Czech Republic) AND Country Rev: 4
  • EU / 13 - Country: EU (Europe) AND Country Rev: 13
  • EU / 33 - Country: EU (Europe) AND Country Rev: 33
  • EU / 53 - Country: EU (Europe) AND Country Rev: 53
  • EU / 78 - Country: EU (Europe) AND Country Rev: 78
  • DE / 7 - Country: DE (Germany) AND Country Rev: 7
  • PL / 4 - Country: PL (Poland) AND Country Rev: 4
  • FR / 5 - Country: FR (France) AND Country Rev: 5
  • GB / 6 - Country: GB (Great Britain) AND Country Rev: 6
  • FI / 4 - Country: FI (Finland) AND Country Rev: 4
  • HU / 4 - Country: HU (Hungary) AND Country Rev: 4
  • ES / 4 - Country: ES (Spain) AND Country Rev: 4
  • IT / 4 - Country: IT (Italy) AND Country Rev: 4
  • US / 0 - Country: US (USA) AND Country Rev: 0
  • CA / 223 - Country: CA (Canada) AND Country Rev: 223
  • BR / 17 - Country: BR (Brazil) AND Country Rev: 17
  • BR / 20 - Country: BR (Brazil) AND Country Rev: 20
  • RU / 50 - Country: RU (Russia) AND Country Rev: 50
  • CN / 38 - Country: CN (China) AND Country Rev: 38
  • CN / 224 - Country: CN (China) AND Country Rev: 224
  • AU / 43 - Country: AU (Australia) AND Country Rev: 43
  • AU / 44 - Country: AU (Australia) AND Country Rev: 44
  • SG / 12 - Country: SG (Singapore) AND Country Rev: 12 (default *)

Some combinations of Country and revision codes are invalid, and will not work together. For example, if you set country to USA, and change only country to “US” and leave revision at “12” that would be invalid. You need to change country / region to “US” and country revision to “0” to have a working combination.

Most users will be able to choose the correct settings from those in the Wireless menu. However, there are many more settings.

Advanced users can see the complete list of settings and their code commit entries here:
For SDK6 routers:
https://bitbucket.org/pedro311/freshtomato-arm/commits/ffb286c7afa64b02bc2136d6bd67ba6f7f6b42b2/raw

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

For example, for SDK6 (ARM models only) builds and country USA, open file “wlc_clm_data.c”
(sysdeps/RT-AC68U/clm/src/wlc_clm_data.c) and go to line ~98738. There, you will 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 */
...
...

In the comment field on the right are valid combinations for country and revision. You can see that country “US” and country rev “12” is NOT a valid setting for the wireless driver. Do not use “#a” or “#r”. They are for debugging/testing and not meant for daily use.

(Default: Singapore / 12).

NOTE: For FreshTomato MIPS SDK5 (RT and RT-N) builds, there is currently only a country selection. Starting with MIPS SDK6 (RT-AC) builds and all ARM-Branches/Versions you will need to choose a country and a country rev. This applies to FreshTomato 2020-6 and later.

Country Rev

See the Country/Region section above. Revision settings only exist in FreshTomato 2020-6 and later.

Bluetooth Coexistence

Options:

  • Disable * (Default)
  • Enable
  • Preemption

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

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

Distance / ACK Timing

(Default: 0).

When a router sends a packet to a network client, the router waits for an ACKnowledgement frame from the client to ensure the packet was received. The fixed 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. That 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 it takes 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. The default value is recommended for most scenarios, except where administrators have a strong knowledge of timing and/or 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 which go 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 might drop returning ACK frames too early, and again resend the original “unacknowledged” packet. This also could lower throughput.

DTIM Interval

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 for them to receive. When in power-save mode, a client device may choose to 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 frames mentioned.

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 access point will release any exsiting buffered broadcast and/or multicast data. (Default: 1). 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. This could increase power consumption. For portable devices, such as laptops, batteries could be drained faster.
  • Longer DTIM Intervals would allow network clients to sleep longer and save more power. However, the router would have to wait to send the data to the the sleeping clients. This forces the router to buffer more of the broadcast/multicast data. The extra buffering at the router could cause overruns if the router didn't have enough capacity to store all that data until it could be sent. In this way, longer intervals could slow throughput. Therefore, wireless client devices may have conflicting requirements for power consumption and communication throughput when in power-save mode. One is wise to balance both priorities.

Fragmentation Threshold

IP fragmentation is a process which happens when the IP layer breaks datagrams into smaller pieces (fragments). The destination host, or sometimes intermediate routers reassemble the fragmented pieces to make the message whole again. This is usually done to reduce the size of the datagrams so that 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 is fragmented into multiple datagrams. Similar to RTS Threshold, tuning the Fragmentation Threshold setting can be useful in reducing frequent collisions on the network. Too low values may result in poor network performance. The reccommended setting is the default value of 2346. (Default: 2346).

Frame Burst

Options

  • Disabled * (Default)
  • 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 a Router/AP and a client device or between two client devices (ad hoc network). 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 there is a mix of those clients that support Frame Burst and those that don't. The wait periods between frames were not originally designed to include data traffic. They were designed to be contention periods where other hosts can capture the medium and send data. The recommended setting is Disabled, unless there are only a very small number of hosts on your network. Broadcom's implementation of this feature is called “Express Technology”.

Maximum Clients

(Default: 128)

This option specifies the maximum number of clients that can be connected to the wireless network. It is not recommened to increase this number, as the result will likely be an overloaded network, and 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

Options:

  • Auto * (Default)
  • 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. It is important to optimize this rate to lower collisions, particularly when multiple devices or services are being run at the same time. This optimization can be essential for applications such as video conferencing and corporate communications.

For small, basic networks, the default setting should work fine. However, on larger networks, it'is recommended that you adjust this setting. If you’ve noticed decreased performance when running multiple streaming devices on your network, it's also advisable to do so. This is especially true when devices are streaming video.

If you don’t run streaming devices simultaneously, using the “Auto” setting is a good option. 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 rate 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. The optimum setting (combined with other custom router settings tailored to your network) will allow you to connect multiple devices that run smoothly and without interruption.

Preamble

Options:

  • Long * (Default)
  • 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 specification 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 detection data transmission errors.

Generally, all wireless devices on the network 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. Current routers and access points have this setting in their web administration or command-line interface.

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

802.11n Preamble

Options:

  • Auto
  • Mixed Mode * (Default)
  • Greenfield
  • GF-BRCM

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

Auto: TBD.

Mixed Mode: Mixed Mode transmissions can be decoded by 802.11a/g clients, providing 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. These compromises alows for backwards compatiblity with earlier protocols, but reduce throughput, compared with Greenfield, or GF-BRCM modes.

Greenfield: This 802.11n mode is also known as “High Throughput” or “HT” mode. In this mode, the protocol improves efficieny by using a high througput modulation method and a shorter preamble. Neither of these is supported on 802.11a/b/g devices. The main compromise, other than backwards compatiblity, is that this mode can reduce throughput on some 802.11n devices not fully compatible with the 802.11n standard.

GF-BRCM: TBD.

Overlapping BSS Coexistence

Options:

  • Off * (default)
  • On

RTS Threshold

When CTS (Clear-to-Send) Protection is on, a host must send a RTS (Request-to-Send) frame to the router to obtain 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 access point/router. Typically, CTS frames are not sent/needed until the client has a data frame to send that meets a certain size threshold. That threshold frame size is set here, in the RTS Threshold field. (Default: 2347).

Transmit Power

This allows you to override regulatory and other limitations and increase or lower the Transmit Power, in mW (milliwatts). The default / recommended setting is “0”, which uses the regulated power level for your chosen country setting. It is recommended that before you increase Transmit Power to improve signal range, you try more conventional methods first. These methods include relocating your router/AP to a more central location, elevating it, and (if supported) using better, external higher gain 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 to snoop on your connection.

Transmission Rate

Options:

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

The default/recommended setting is Auto.

AC-PHY Interference Mitigation

This option is only available for AC capable wireless ICs / interfaces

  • 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)

Interference Mitigation

This option is only available for NON-AC capable wireless ICs / interfaces

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

WMM

Wireless Multimedia options:

  • Auto
  • Disable
  • Enable * (default and also recommended setup)

Note: Disabling WMM will/should result in clients falling back to 802.11a/g rates (54 Mbit/s).

No ACK

No Acknowledgement options:

  • Disable * (default)
  • Enable

APSD Mode

Automatic Power Save Delivery options:

  • Disable
  • Enable * (default)

Wireless Multicast Forwarding

Options:

  • Disable * (default)
  • Enable

Turbo QAM (Requires Wireless Network Mode set to Auto)

Enable 256-QAM (MCS 8/9) support. Wireless Mode must be set to Auto. Note: Not all router support that feature.

Explicit beamforming

Router and wireless client both support beamforming technology. Allow these devices to communicate channel estimation and steering direction to each other to improve download and upload speed. Note: Not all router support that feature.

Universal/Implicit beamforming

For Legacy wireless network adapter that do no support beamforming, the router estimates the channel and determines the steering direction to improve the downlink speed. (It is also called Implicit Beamforming) Note: Not all router support that feature.

Air Time Fairness

Enable/Provide Airtime Fairness between multiple links.

wireless.txt · Last modified: 2021/07/19 07:00 by m_ars