Ubiquiti airFiber 24HD
24 GHz Full Duplex Point-to-Point 2 Gbps Radio

Features:

Benefits:

Best-in-Class Performance and Range

Our INVICTUS custom silicon dramatically improves wireless performance. The AF-24HD model supports the dense modulation rates, up to 256QAM, that are required for high data rates, up to 2 Gbps. The airFiber AF-24/AF-24HD features the most powerful automatic compensation for path loss degradation due to rain fade, so it provides the best range among 24 GHz products and allows for constellation threshold extension.

Addressing the Under-served

airFiber core networks backbones can be instantly and cost-effectively deployed anywhere, bringing Internet deep into the unserved areas of the world.

Plug and Play Installation

Utilizing precision mounting hardware combined with a dynamic RSSI indicator, airFiber can be easily deployed by a single installer. Integrated GPS receivers automatically calculate position and timing parameters in the background, providing a true plug and play installation experience.

Hybrid Division Duplex (HDD)

HDD provides the best of both worlds — latency performance of Frequency Division Duplex (FDD) with the spectral efficiency of Time Division Duplex (TDD).

Breakthrough Radio Design

airFiber is the result of 100's of R&D years in radio design culminating in the most advanced, application-specific radio solution ever built for the worldwide 24GHz license-free band. It is based on a highly flexible FPGA architecture that can further be field optimized through firmware upgrades.

Superior 24 GHz Performance

Systems for millimeter-wave frequencies typically experience RF (Radio Frequency) losses, which occur when part of the RF is lost in the switches and filters. The Ubiquiti R&D team eliminated such RF losses with separate TX and RX antennas, so the link budget is robust and airFiber AF24HD has better noise figure and higher transmit power efficiency.

Robust Mechanical Assembly

An independent lab has tested the airFiber mechanical assembly to meet MIL-STD-810G, a rigorous United States MIL-STD (Military Standard) that defines a variety of challenging environmental conditions. The mechanical assembly has also undergone vibration testing using an extended version of IEC 60068-2-6, an environmental standard of the IEC (International Electrotechnical Commission).

Product Views:

Specifications:

airFiber AF-24HD Specification
Operating Frequency	24.05 – 24.25 GHz
Dimensions	593 x 768 x 370 mm (23.35 x 30.24 x 14.57")
Weight	17.3 kg (38.14 lb) Mount Included
Max. Power Consumption	50W
Power Supply	50V, 1.2A PoE GigE Adapter (Included)
Power Method	Passive Power over Ethernet
Supported Voltage Range	42-58VDC
Certifications	CE, FCC, IC
Wind Loading	770 N @ 200 km/hr (170 lbf @ 125 mph)
Wind Survivability	200 km/hr (125 mph)
Mounting	Pole Mount Kit (Included)
Operating Temperature	-40 to 55°C (-40 to 131° F)
LEDs	(8) Status LEDs: Data Port Speed Data Port Link/Activity Configuration Port Speed Configuration Port Link/Activity GPS Synchronization Modulation Mode Master/Slave RF Status (1) Two-Digit LED Display Calibrated in dBm
Interface
Data Port	(1) 10/100/1000 Ethernet Port
Configuration Port	(1) 10/100 Ethernet Port
Auxiliary Port	(1) RJ-12, Alignment Tone Port
Interface
Maximum Throughput	2 Gbps
Maximum Range	20+ km
Packets per Second	> 1 Million
Encryption	128-Bit AES
Uplink/Downlink Ratio	50% Fixed
airFiber AF24HD Radio Frequency
GPS	GPS Clock Synchronization
Transceiver
EIRP	~33 dBm (FCC/IC), ~20 dBm (CE)
Frequency Accuracy	±2.5 ppm without GPS Synchronization ±0.2 ppm with GPS Synchronization
Channel Bandwidth	100 MHz
Operating Channels	24.1 GHz, 24.2 GHz
Modulation	256QAM MIMO 64QAM MIMO 16QAM MIMO QPSK MIMO QPSK SISO ¼x QPSK SISO
Integrated Split Antenna
TX Gain	33 dBi
RX Gain	40 dBi
Beamwidth	< 3.5°
Front-to-Back Ratio	70 dB
Polarity	Dual-Slant Polarization
Cross-Polarity Isolation	> 28 dB

* FDD = (2) 100 MHz channels and TDD = (1) 100 MHz channel

Receive Sensitivity:

airFiber AF-24HD Receive Sensitivity
Modulation	Sensitivity	FDD Capacity*	TDD Capacity*
256QAM	-60 dBm	2000 Mbps	1024 Mbps
64QAM	-66 dBm	1500 Mbps	760 Mbps
16QAM	-72 dBm	1000 Mbps	507 Mbps
QPSK MIMO	-78 dBm	500 Mbps	253 Mbps
QPSK SISO	-80 dBm	250 Mbps	127 Mbps
¼x QPSK SISO	-87 dBm	62.5 Mbps	31.7 Mbps

Design Guide:

Getting the Most from a Versatile Platform

The airFiber AF24 is a versatile platform that can be optimized for a variety of conditions. The user interface is simple and intuitive, but there are numerous configuration parameters. The AF24 is a veritable Swiss Army knife when it comes to versatility and options to address different needs.

Configuration for Ultimate Speed and Latency Performance

Typically the best speed and lowest latency will be obtained with the AF24 configured as a full-duplex system using Frequency Division Duplexing (FDD). The data streams generated by the AF24 are simultaneously transferred across the wireless link. The transmitter and receiver are running concurrently in time. Because of the trade-off between bandwidth resources and propagation conditions, this approach is typically reserved for links in areas where installations are in clear line-of-sight conditions and free of reflected energy such as that generated by heavy rain or intermediate objects. Installations that are subject to Fresnel reflections or highly scattered environments may experience some level of degradation at great range.

For Full Duplex mode, the TX and RX Frequencies should be different.

Full-Duplex Diagram

Configuration for Highest Possible Availability and Robustness

Links that are installed in environments that are highly reflective or subject to considerable scattering due to heavy rain or foliage loss are typically better suited to half-duplex configurations. In this case the frequency and bandwidth resources are shared on a Time Division Duplexing (TDD) basis, and the system can accept higher levels of propagation distortion. The trade-offs are reduced throughput and slightly higher latency.

For Half Duplex mode (default), the TX and RX Frequencies can be the same or different to suit local interference.

Half-Duplex Diagram

The AF24 radio system has the ability to manage time and bandwidth resources, similar to other systems utilizing different modulation schemes that are scaled according to the noise, interference, and quality of the propagation channel. The AF24 system also automatically scales its modulation based on channel quality but has the ability to be reconfigured from a time/bandwidth perspective to allow for best possible performance. In many regards the suitability of the duplexing scheme needs to be taken into account based on the ultimate goals of the user. Just as channel conditions have an effect on the modulation scheme selection, there are effects on duplexing modes to consider as well.

Alignment

Tips

• We recommend using a pair of installers in constant communication because in the fine-tuning stage, one installer makes azimuth and elevation adjustments on one airFiber radio while the other installer reports the received signal level at the other airFiber radio. (Fine-tuning is necessary because the main lobe of the receiver is more narrow than that of the transmitter, in both azimuth and elevation.)
• To accurately align the airFiber radios for best performance, you MUST align only one end of the link at a time.
• As a safety precaution, ground the airFiber radios to grounded masts, poles, towers, or grounding bars. Use ground wires with a minimum diameter of 8 AWG (10 mm2) and a maximum length of 1 meter. For guidelines about grounding and lightning protection, follow your local electrical regulatory codes.
• For more convenient alignment, you may consider using long-range scopes (not included) temporarily attached to your airFiber radios.
• You may need to use additional hardware to compensate for issues such as the improper orientation of a mounting pole or significant elevation differences between the airFiber radios.

Establishing a Preliminary Link

Adjust the positions of the airFiber radios to be within a few degrees of the line of sight between them. The Master must be aimed first at the Slave because the Slave does not transmit any RF signal until it detects transmissions from the Master.

Fine-Tuning the Link

The Azimuth (AZ) and Elevation (EL) Adjustment Bolts of the Alignment Bracket adjust the azimuth and elevation within a range of ±10°. For accurate alignment, make adjustments on one end of the link while the other installer reports the received signal level at the other end of the link.

Note: Do NOT make simultaneous adjustments on the Master and Slave.

Alternate adjustments between the airFiber radios, until you achieve a symmetric link, with the received signal levels within 1 dB of each other. This ensures the best possible data rate between the airFiber radios.

Lock the alignment on both airFiber radios by tightening all eight Lock Bolts on the Alignment Bracket. Observe the LED Display on each airFiber AF24 to ensure that the value remains constant. If the LED value changes during the locking process, loosen the Lock Bolts, finalize the alignment of each airFiber AF24 again, and retighten the Lock Bolts.

Summary

The following summarizes these guidelines. We have seen installations that greatly deviate from these guidelines yet still work very well. Each installation is different and will need to be optimized based on the conditions present in the field and the goals of the user.

Frequency Division Duplexing (FDD) is best for:

• Maximum possible throughput
• Minimum possible latency
• Installations that are free of reflective and scattering elements
• Areas that see lower amounts of rainfall
• Scenarios with more available spectrum

Time Division Duplexing (TDD) is best for:

• Co-location with other master nodes
• Robustness in areas that see the most rainfall
• Scenarios with less available spectrum
• Less than ideal installations, such as installations near obstructions or scattering elements

These guidelines are only general recommendations. For example, we have successfully co-located FDD links and installed FDD links that work on a single frequency at short range.

Technology:

airFiber Radio

• Superior Throughput with No RF Losses
• Innovative Zero IF Radio
• Flexible FPGA Architecture
• Revolutionary Media Access Control
• Multiple Input, Multiple Output Spatial Multiplexing
• Time and Bandwidth Resource Management

Superior Throughput with No RF Losses
Starting with the silicon chip, the Ubiquiti Networks™ Research and Development (R&D) team created airFiber, a sophisticated system robust enough to perform in the harshest RF noise environments. Designed for high-performance backhauls and outdoor, PtP (Point-to-Point) bridging, airFiber AF24 efficiently delivers up to 1.5+ Gbps, aggregate throughput. Systems for millimeter-wave frequencies typically experience RF (Radio Frequency) losses, which occur when part of the RF is lost in the switches and filters. The R&D team eliminated such RF losses, so the link budget is robust and airFiber has better noise figure and higher transmit power efficiency.

Innovative Zero IF Radio
Designed with two multiplexed transmitters and two multiplexed receivers, the airFiber radio is Zero IF (Intermediate Frequency); it is a direct-conversion radio that generates and decodes the received signal at baseband, so there is no intermediate frequency and virtually no signal loss between the radio and antenna. The R&D team invented numerous algorithms to control the amplitude and phase. The end results are excellent spectral shape and freedom from spurious responses that stem from conversion by-products.

Flexible FPGA Architecture
The highly flexible FPGA (Field Programmable Gate Array) architecture can be further field-optimized through firmware upgrades. airFiber features both sophistication and reprogrammability; you can add features as they become available and enhance system performance through firmware upgrades.

Revolutionary Media Access Control
The R&D team created a new MAC (Media Access Control), which is the link between the radio control (FPGA) and physical network. All real-time packet processing is placed in dedicated parallel hardware rather than in software. All real-time functions related to digital signal processing and coding are handled in fully custom hardware that is reconfigurable, so the MAC is extremely powerful while retaining the inherent flexibility of a software-defined system.

Multiple Input, Multiple Output Spatial Multiplexing
airFiber incorporates an OFDM (Orthogonal Frequency Division Multiplexing) system to use linear, 2x2, MIMO (Multiple Input, Multiple Output) spatial multiplexing, which has two benefits: enhanced spectral efficiency and the ability to maintain reliable links in poor propagation environments.

Time and Bandwidth Resource Management
airFiber automatically scales its modulation based on channel quality but has the ability to be reconfigured from a time/bandwidth perspective to enable the best possible performance in a wide variety of deployment scenarios.

Dual-Antenna Architecture

• Innovative Dual-Antenna Architecture
• Synchronous Data Transmission and Reception
• Robust Mechanical Assembly

Innovative Dual-Antenna Architecture
The Ubiquiti Networks™ R&D (Research and Development) team created airFiber for outdoor PtP (Point-to-Point) bridging and high-performance network backhauls. The team invented a market-leading, dual-antenna architecture. Each airFiber unit features a radical departure from industry practice: a one-piece "monocoque" molding comprising two complete antenna systems and a mechanical back-plane. "Monocoque" means that the exterior skin supports the structural load of the airFiber hardware; this same concept is used to construct lightweight, rigid structures, such as those used for Formula One race cars. Due to its single-piece, injection-molded architecture, airFiber adds lightness in weight and affordability to its list of advantages.

Synchronous Data Transmission and Reception
If airFiber had been constructed using conventional methods and individual mechanical parts, collimation distortion (the two antenna beams being skewed with respect to one another) would likely have a negative impact on link budgets and overall system performance. With airFiber's innovative, one-piece assembly, the two antennas can be aimed at exactly the same point in space with a high degree of accuracy and repeatability. airFiber features a dual-independent, 2x2 MIMO, high-gain reflector antenna system. On each airFiber unit, the smaller antenna on the bottom transmits, and the larger antenna on the top receives. The main lobe of the receiver is more narrow than that of the transmitter, in both azimuth and elevation, so peak performance requires precise aiming and fine-tuning of the alignment between the airFiber units during installation.

Robust Mechanical Assembly
An independent lab has tested the airFiber mechanical assembly to meet MIL-STD-810G, a rigorous United States military standard that defines a variety of challenging environmental conditions. The airFiber mechanical assembly has also undergone vibration testing using an extended version of IEC 60068-2-6, an environmental standard of the IEC (International Electrotechnical Commission). By industry standards, the typical test looks for no observable mechanical failures after 3 hours of sinusoidal sweeps. The airFiber R&D team set the bar higher for airFiber, which passed an extended, 3-axis test that ran for 9 hours to ensure no mechanical failures. (Extended 9-hour testing is often done for MIL-STD compliance.)

Software:

Loaded with Powerful Features

airOS F is an intuitive, versatile, highly developed Ubiquiti firmware technology that resides on airFiber. It is exceptionally intuitive and was designed to require no training to operate. Behind the user interface is a powerful firmware architecture which enables hi-performance network backhauls.

airOS F Tools

• Speed Test
• Antenna Alignment
• Device Discovery
• Site Survey
• Ping
• Traceroute

airOS F Integrated Technologies

airFiber’s purpose-built hardware provides superior wireless performance, higher capacity, and lower latency. Unlike standard WiFi protocols, Ubiquiti airFiber’s Hybrid Division Duplex (HDD) provides the best of both worlds — latency performance of Frequency Division Duplex (FDD) with the spectral efficiency of Time Division Duplex (TDD).

Documentation:

Download the Ubiquiti airFiber Datasheet (PDF).

Download the Ubiquiti airFiber Design Guide Datasheet (PDF).