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UniFi Video is an obsolete product line.

This application and its related devices will no longer receive any manner of technical support, including functional and security updates. Additionally, there will be no further updates to Help Center content pertaining to UniFi Video.

airFiber - Frequently Asked Questions (FAQs)

What is the minimum link distance between Master and Slave?

The minimum distance between Master and Slave ends of the link will depend on the model:

  • airFiber5: 10 meters
  • airFiber 2X, 3X, 4X, and 5X: this varies depending on the antenna gain, but a general rule would be 25 meters
  • airFiber24: 25 meters (using firmware 2.0 or higher)
  • airFiber11: 25 meters 

What is the difference between Hybrid Division Duplexing (HDD) & Frequency Division Duplexing (FDD)?

Hybrid Division Duplexing (HDD), is a special, proprietary wireless mode which allows for half-duplex wireless operation, where same frequency is used on both TX/RX chains. This proprietary mode is similar to Time Division Duplexing (TDD) and allows for more resilient radio links, at longer distances. 

HDD.png

The Frequency Division Duplexing (FDD), is a wireless protocol that allows for full-duplex wireless operation. It uses separate frequencies for TX/RX chains on the same radio. Given the isolation, this wireless mode allows for the highest available throughput.

FDD.png

airFiber radios can operate in Full-Duplex (FDD) or Half-Duplex (HDD) mode. Full-Duplex offers the highest performance and lower latency (below 1ms) but generally speaking, requires perfect Line of Sight and perfect alignment. On the other hand, Half-Duplex mode is more tolerant to misalignment and in certain cases can work in nLoS (near Line of Sight) scenarios, especially at lower frequencies, like in the 2.4GHz band (ex. AF-2X).

Important: When the radios are running in Half-Duplex mode, it's recommended to always set the same Wireless Mode (Master or Slave) in all the units located at a specific location. 

Which airFiber device models support FDD & HDD modes of wireless operation?

Device Model

Full-Duplex (FDD)

Half-Duplex (HDD)

AF-2X - Yes
AF-3X - Yes
AF-4X - Yes
AF-5X - Yes
AF-5/AF-5U Yes Yes
AF24 Yes Yes
AF24HD Yes Yes
AF-11 Yes -
AF-5XHD - Yes
AF60 - Yes
AF60-LR - Yes

For more information, along with other airFiber features in the different User Guides downloadable in our Downloads page, under the Documentation section. 

How do Half-Duplex & Full-Duplex modes work specifically with airFiber devices?

When you think of any airMAX and airFiber X-series products, you immediately think Half Duplex. With those products, you choose one frequency and width. Both the AP and CPE use that same frequency/width to send data in both directions. The AF5 and airMAX both do it by taking turns sending data, one side at a time. While there are largely technical and hardware differences in how airMAX and airFiber send data using a single channel, just remember that in both cases it's one side sending at a time. That's the AF5 in Half Duplex and AF-2X/AF-3X/AF-4X/AF-5X.

If you are used to picking a single open channel using airMAX, or replacing another Half Duplex link, using Half Duplex with AF5 or any AF-X model will seem very familiar and easy to understand. Just pick a channel that's open on both sides, and use it for both directions.

One very important thing to understand is that Half Duplex with AF5 is not half speed. It's not like Half Duplex ethernet where you use fewer wires and run at half the speed. With AF5, you get the same throughput per spectrum used, in both Half and Full Duplex. It's not whether you use half or full that determines throughput, it's the amount of spectrum you use. And in fact, under some conditions, Half Duplex will provide better total throughput than Full Duplex.

The other important Half Duplex difference between AF5 and airMAX is the AF5 send/receive time slots are fixed, while in airMAX they're variable. airMAX will adjust the time slots for the direction that needs it most at any given time, being able to assign nearly all the bandwidth to one direction. But in AF5, in order to keep the latency down, it doesn't have time to make those adjustments. The send / receive time slots or Duty Cycle is fixed so both sides can instantly transfer any data that comes along. In v2.1, the Duty Cycle is always 50% which means 50/50 send/receive. Since firmware version 3.2, you can choose among different duty cycle menu choices like 75%, which would mean 75% download and 25% upload; and 67%, which would mean 67% download and 33% upload. 

There are more advanced ways to use Half Duplex, but we'll skip those for now and move on to Full Duplex. With Full Duplex, you use separate channels for each direction. One channel is exclusively used for transmission, and another different channel is exclusively used for reception. Both sides can send at the exact same time, hence the name Full Duplex. Because each frequency is only used in one direction, the one-way flow is doubled compared to Half Duplex. But, in order to send in both directions, you now need two channels and more spectrum. It's important to remember that any speed increase in using Full Duplex, is only achieved by increasing the use of spectrum.

Using Full Duplex does have some interesting advantages. For starters, each end of the link has noise on a different frequency, so you can independently tune the best reception frequency for each side based on noise detected. You no longer have to find a common ground channel that's open on both sides.

The other advantage of Full Duplex is that the channel width for each direction can be different. You can provide a wider channel for faster downloads, and a narrower channel for uploads and save spectrum by doing that.

Note: Full Duplex can self-interfere if the power is too high, and the channels too close. Cranking the power to the max is counterproductive with Full Duplex. Between 43-45 dBm seems to be a limit above which higher constellations can't be maintained and performance will start to drop.

Now getting back to Half Duplex. You don't have to use just a single channel for Half Duplex. Nothing says you can't use one for each direction. But the AF5, will still only send in one direction at a time, so this can waste spectrum. But using two channels in half can actually be very useful at times. Let say you can only find a different 20 wide free channel on each side of the link. And they both overlap with 10 shared widths in the middle. You can't use Full Duplex because they will self-interfere. Or you could settle for the common 10 wide in the middle. But the best solution is to use Half Duplex with two slightly different channels. Because each side sends one at a time, you won't self-interfere in the middle 10. And the increased bandwidth allowed by this will double your throughput compared to settling for the shared 10 wide in the middle.

How much does rainfall impact airFiber links?

Radio signals undergo significant levels of attenuation from humidity and precipitation: around 8GHz and higher. Therefore, it's always recommended to consider humidity and rainfall as factors in link planning.

Due to their acute wavelengths, signals in the 24GHz band encounter additional atmospheric attenuation beyond that which is expected from free space path loss due to water absorption, including rain fade. A general guideline is an additional loss of 1-3 dB per kilometer. The amount of additional atmospheric attenuation will vary, depending on your specific installation environment (the world has a variety of rainfall zones).

For example, links exposed to 25 mm/hr of rainfall could undergo additional 4dB of attenuation per km. The table below illustrates the estimated additional attenuation at various rainfall rates and distances, based on information from the FCC bulletin.

Estimated rainfall attenuation rates at 24GHz. 

Distance 1.25 mm/hr 5 mm/hr 25 mm/hr
1 km 0.2 dB 0.7 dB 4 dB
2 km 0.4 dB 1.4 dB 8 dB
3 km 0.6 dB 2.1 dB 12 dB
4 km 0.8 dB 2.8 dB 16 dB
5 km 1 dB 3.5 dB 20 dB 

Can the AF5 connect to the AF5U?

AF5 is a radio system designed to work between 5470MHz and 5850MHz (or 5950MHz in some regions). AF5-U is a radio system designed to work between 5725MHz and 5850MHz (or 6200MHz in some regions). Both models support the UNII-3 band, 5725MHz to 5850MHz*, so a radio link using one AF5 and one AF5U on the other end will work fine as long as they use any frequency within the UNII-3 band.

Note: International units can work up to 5950MHz depending on country limits.

Can the AF24 connect to the AF24HD?

AF24 and AF24-HD can create a link together. However maximum throughput will be limited by the AF24 (up to 6X, 64QAM).

Can the AF-5X connect to the AF-5XHD?

No, the AF5XHD is a brand new architecture that is incompatible with the AF5X.

How does airFiber handle traffic prioritization & QOS?

airFiber devices operate at layer-2 with built-in quality of service (QoS) handling frame prioritization based on 802.1p priority values located in the VLAN field in the Ethernet frame header. Like with airMAX, these values should be applied prior to arriving at the airFiber in order to receive their respective prioritization. Depending on the values configured here, airFiber will automatically prioritize the traffic accordingly as seen in the table to the right. Frames with 802.1p value set to 7 are the highest priority and frames with 802.1p value set to 1 are the lowest priority. 

802.1p CoS Value

airFiber Priority

0 2
1 0
2 1
3 3
4 4
5 5
6 6
7 7

What Output (TX) Power and Receive (RX) Sensitivity levels are required for certain modulation rates?

In order to negotiate at a given Modulation & Coding Scheme (MCS) rate, radios require minimum signal thresholds. Radio sensitivity information is available on our product datasheets (found on our Downloads page).

Additionally, radio output power also determines modulation rate, since higher output powers cause distortion in symbol mapping at transmitter/receiver radios. Compared to competitor radios, airFiber radios operate cleanly to maximize throughput efficiency at every output power level.

The following two tables shown below help explain these two concepts:

  1. The first table shows modulation rates according to maximum TX Power.
  2. The second table shows modulation rates according to minimum radio sensitivity, based on given channel widths.

Note: Remember that EIRP (and consequently, maximum output power) depends on country code and frequency.

Suggested Max TX Power:

  Modulation Output Power
8x 19-20 dBm
6x  21-22 dBm
4x  23-24 dBm
1-2x  26 dBm
1/4x 26 dBm

From the table above we can conclude that to achieve up to 8x modulation it's highly recommended to use output power up to 20dBm. If higher levels are used, for example 21dBm output power, it's possible that you'd only get up to 6x.

Suggested RX Sensitivity Levels:

Radio sensitivity depends on channel width and modulation, for example if you want to get 8x modulation using 30MHz channel you need a received signal strength of -62dBm or better (like -60dBm, -55dBm, etc...).

User Tip: It's a good practice to keep a certain fade margin to prepare for weather changes or other situations that could temporarily affect your link. Recommended fade margins depend on your area and link distance. In most cases, it's recommended to keep at least 5dBm of fade margin.

BW (MHz)

Rate

RX Power (dBm)

50

8x

-60

50

6x

-67

50

4x

-74

50

2x

-81

50

1x

-83

 

 

 

40

8x

-61

40

6x

-68

40

4x

-75

40

2x

-82

40

1x

-84

 

 

 

30

8x

-62

30

6x

-69

30

4x

-76

30

2x

-83

30

1x

-85

 

 

 

20

8x

-64

20

6x

-71

20

4x

-78

20

2x

-85

20

1x

-87

 

 

 

10

8x

-66

10

6x

-74

10

4x

-81

10

2x

-88

10

1x

-90

What is the BER (Bit Error Rate) on airFiber radios?

BER (Bit Error Rate) is a very popular measurement of the percentage of packets with errors on a digital link. A BER value of 10 - 6 = (1/1000000), means that of every 1.000.000 received packets 1 has errors and must be retransmitted, which is considered a very good link. On the other hand, a link with a BER of 10 - 3 = (1/1000), is considered a very bad or damaged link (according to the IEC 608720-3 and IEC 60801-4).

Thanks to airFiber's revolutionary system it has an effective BER = 0, which means that of every 1.000.000.000 received packets 0 has errors. How is this possible? airFiber uses hitless adaptive modulation and an ARQ scheme over the radio link to ensure that no bit errors are delivered over the link. More information about BER available here: https://en.wikipedia.org/wiki/Bit_error_rate

Is auto modulation a hitless protocol?

Yes, airFiber Adaptive Modulation is hitless. airFiber uses a selective acknowledgment-based protocol to ensure that no packets are lost as a result of link adjustments such as changes in modulation. The only thing you should see during a transition is a short spike in latency while the rates change. Make sure Flow Control is enabled to avoid any potential Rx buffer overflow when the link is heavily loaded.

If the link needs to modulate down it will be capable of carrying less traffic and thus may lose packets as a result of overflow (i.e. the user rate is 700 Mbits and the link negotiated to 500 Mbits).

Which antennas are compatible with AF-4X?

airFiber 4X (AF-4X) works with any 4.9GHz-capable MIMO antenna. The AF-4X is a high-performance radio designed to work in the licensed 4.9GHz band, also known as the public safety band. A license is required to use these radios in the United States. US units operate from 4,940MHz to 4,990MHz, and international units (only for export) can operate from 4.7-4.99GHz.

Important: You must have a license to use any 4GHz frequency. You will be breaking the law if you fail to comply.

The AF-4X works with any 4.9GHz-capable MIMO antenna. It is compatible with the Ubiquiti airFiber Dish 30dBi and 34dBi models, as well as the RocketDish 30dBi and 34dBi antennas. Unfortunately, since those antennas have been designed for the 5GHz band, the performance in the 4.9GHz range is lower. Therefore, it's important to consider this and use the following values in your calculations and in the data you enter into the airFiber 4X Wireless tab.

Shown below are a list of Ubiquiti antennas that can be used with the AF-4X and their corresponding gain.

  Antenna Gain at 4.9GHz
AF-5G30-S45 26dBi
AF-5G34-S45 30dBi
RD-5G30 26dBi
RD-5G34 30dBi
MonsterDish 34dBi
Note: The AF-5G23-S45 antenna is not recommended for the 4.9GHz, since its antenna gain at 4.9GHz is around 17-18dBi.

What are are some recommendations for grounding airFiber units?

Ubiquiti recommends professional installers follow local regulatory regulations and guidelines concerning grounding. Improperly grounding airFiber and other network devices, including inadequate grounding installation, automatically voids the device warranty.

Listed below are some general tips related to grounding that may reduce the chances that your airFiber device may be damaged due to ESD & other related events.

  1. First, you need a properly grounded mast, pole, tower or grounding bar located next to the airFiber. The maximum distance between the airFiber unit and the grounding point is 1 meter (3ft). If you don't have a grounding point close enough to the radio or you are not sure about the quality of the grounding installation, it's highly recommended to contact a certified electrician in your area to check it and install new grounding if necessary.
  2. The ground wire diameter must be a minimum of 8 AWG (10AWG for AF-5XHD), and the maximum cable length must be 1 meter (3ft).
  3. Proper connectors should be used on both sides of the cable to ensure good conductivity; the diameter of the connectors needs to be appropriate for the diameter of the wire you are using.
  4. Remember to secure the nut to the grounding bolt after you insert the grounding connector.
  5. It's also highly recommended to use two Outdoor Gigabit PoE surge protectors, like the Ubiquiti Ethernet Surge Protector, model ETH-SP.  High quality outdoor shielded cable and connectors must be used in the cable that connects the AF’s DATA port and the ETH-SP, as well as from the ETH-SP to the PoE Adapter.  
  6. Finally, make sure that the AC outlet where the PoE Adapter/switch is connected, also has a proper grounding installation.

Note: We also recommend using Ubiquiti Ethernet Surge Suppressors that offers superior ESD protection. You can also use any high-quality Gigabit surge suppressor that uses the 4 pairs for data and power.

What do the LED patterns on the AF24 unit mean?

The AF24 unit displays information for the radio operator helpful in alignment and troubleshooting an link. The table below explains the meaning for each LED pattern. Use the following image as reference.

  

If viewing on mobile please turn device horizontally for better viewing of tables.

 

DATA Port

AUX Port

LED Display

CONFIG Port

Left LED Speed
  • Off - 10/100 Mbps Negotiation
  • On - 1000 Mbps Negotiations
GPS
  • Off - No GPS Sync
  • On - Operational; Strong GPS Signal
  • Normal* - Operational; Weak GPS Signal

Master/Slave Unit

  • Off - Slave Mode
  • On - Master Mode

Speed

  • Off - 10 Mbps Negotiation
  • On - 100 Mbps Negotiation
Middle N/A N/A

 

 LED Display - RX Power (-dBm)

  • Number - Decodable RX Signal
  • Flashing Number - Undecodable RX Signal
  • "oL" - Overload Condition (too strong of signal; suggestion is to lower TX power)

N/A

Right LED

Link Activity

  • Off - No Ethernet Link
  • On - Ethernet Link Establish
  • Random* - Ethernet Activity (Data passing, etc.)

Modulation

  • Off - 1x (QPSK SISO)
  • Short* - 2x (QPSK MIMO)
  • Normal* - 4x (16QAM MIMO)
  • Long* - 6x (64QAM MIMO)

RF Link Status

  • Off - RF Offline (The radio is not communicating with any other stations)
  • Short* - Syncing (The radio is syncing with the GPS hardware)
  • Normal* - Beaconing (The radio is looking for a slave radio to associate and begin communicating)
  • Long* - Registering (The radio is associating/initializing an RF Link with another radio)
  • On - Operational (The radio link is 'live' and radios may pass traffic over the wireless interface)

Link Activity

  • Off - No Ethernet Link
  • On - Ethernet Link Establish
  • Random* - Ethernet Activity

* Short Flash (1:3 on/off cycle) - Normal Flash (1:1 on/off cycle) - Long Flash (3:1 on/off cycle) - Random* = Does not follow a set cycle, flashing may be intermittent.

What do the LED patterns on AF-X units mean?

The information displayed by AF-X units helps operators with alignment, monitoring & troubleshooting. The tables below explain the meaning for each LED pattern & ports. Use the following images for reference.

  

Management Port: 10/100 Mbps, secured Ethernet port for configuration. In-Band Management is enabled by default in the airFiber Configuration Interface. When In-Band Management is disabled, the MGMT port is the only port that can monitor, configure, and/or update firmware.

Reset Button: To reset to factory defaults, press and hold the Reset button for more than 10 seconds while the device is already powered on.

Data Port: Gigabit PoE port for handling all user traffic and powering the device.

 

 

Once fully booted, the Signal 1-4 LEDs act as a bar graph showing how close the AF-X is to ideal aiming. This is auto-scaled based on the link range, the antenna gains, and the configured TX power of the remote AF-X. Each Signal LED has three possible states: On, Flashing, and Off. All Signal LEDs would be on and steady in an ideal link. If the link has a 1 dB loss, the Signal 4 LED will flash; a 2 dB loss and the Signal 4 LED will turn off. The full bar graph LED states are shown below. A perfectly aligned link should show all four Signal LEDs ON.

 

Note: In order to calculate an accurate expected signal level, you will need to enter the right antenna gain and cable loss in the Wireless tab. If you enter different values, you will see inaccurate results

Besides the Signal LEDs, the AF-X has other additional LEDs which offer additional information. See the table below for more information:  

LED

State

Status

Link

Off

Short Flash*

Normal Flash*

Long Flash*

On

RF Off

Syncing

Beaconing

Registering

Operational

GPS

Off

Normal Flash*

On

No GPS Synchronization

Non-Operational (Weak Signal)

Operational (Strong Signal)

Management

Off

On

Random Flashing

No Ethernet Link

Ethernet Link Established

Ethernet Activity

Data

Off 

On 

Random Flashing

No Ethernet Link 

Ethernet Link Established 

Ethernet Activity

Power

Off

On

No Power

Powered on

* Short Flash (1:3 on/off cycle) - Normal Flash (1:1 on/off cycle) - Long Flash (3:1 on/off cycle)

What do the LED patterns on AF5/AF5U units mean?

The airFiber 5/5U incorporates two LED displays: one showing local Rx signal; the other, remote Rx signal strength. The info displayed by AF5/AF5U units helps operators with alignment, monitoring & troubleshooting. The tables below explain the meaning for each LED pattern & ports. Use the following images for reference. 

Reset Button: To reset to factory defaults, press and hold the Reset button for more than five seconds while the unit is already powered on.

 

Remote Display: Displays the received signal strength in dBm of the remote airFiber radio.

 

Local Display: Displays the received signal strength in dBm of the local airFiber radio. 

 

Management Port: 10/100 Mbps, secured port for configuration. By default, this is the only port that can monitor, configure, and/or update firmware. 

 

Aux Port: Port for audio tone aiming.

 

Data Port: 10/100/1000 Mbps port handles all user traffic.  

 

LEDs

LED Label

State

Status

GPS

Off

On

Normal Flash

No GPS Sync

Operational (Stron signal)

Non-Operational (Weak signal)

Master

Off

On

Slave Mode

Master Mode

Link Status

Off

Short Flash

 

 

Normal

Long Flash

On

RF Off

Syning (DFS countries only)

* DFS CAC

* RADAR Detected

Beaconing 

Registering

Operational

Remote

On

Displays the received signal

strength in dBm of the remote

airFiber radio

Local

On

Displays the received signal

strength in dBm of the remote

airFiber radio

Overload

Fast Flash

Overload Condition (Identify

and eliminate any source of

strong in‑band interference.)

(Unlabeled) On  10X (1024QAM) 
8x On 256QAM MIMO 
6x On  64QAM MIMO
4X  On  16QAM MIMO 
2X  Long Flash  QPSK MIMO
1X  Normal Flash  1x QPSK xRT™**
0.25X  Short Flash  ¼x QPSK xRT**

* Short Flash (1:3 on/off cycle) · Normal Flash (1:1 on/off cycle) · Long Flash (3:1 on/off cycle)

** Extreme Range Technology

Port LEDs

Port

LED Label

State

Status

Management  Act

Off

On

Random Flashing

No Ethernet link

Ethernet Link Established

Ethernet activity

Speed

Off

On

10Mbps

100Mbps

Data  Act

Off

On

Random Flashing

No Ethernet link

Ethernet Link Established

Ethernet activity

Speed

Off

On

10/100Mbps 

1000Mbps

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