modified on 17 December 2012 at 21:59 ••• 59,312 views

Getting Started with airMAX

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Product Options for Different Scenarios

In fixed outdoor wireless communications there are two primary deployment methods used for distributing wireless: Point-to-Point (PtP), and Point-to-Multipoint (PtMP).

  • Point-to-Point (PtP): Connects two locations, usually multiple km, essentially forming an Ethernet bridge.
  • Point-to-Multipoint links (PtMP): Connects three or more locations, using one Base Station (or Access Point) and multiple CPE devices (Stations) connected to the Access Point.


PtP Links

PtP link

The following suggestions are based on reference distances. Real results depend on environmental interference, Line of Sight, EIRP limits and other factors. The products that follow are sorted by distance; shortest to longest.

  • Short distance (0-5 km)
  • Loco M: Ideal for very short distance links. Lowest cost PtP solution
  • Nano M: Very popular product for short links, frequently used for video surveillance due to its dual-Ethernet port capability
  • Medium distance (5-15 km)
  • airGrid M: Ideal for low throughput links, where connectivity, wind-loading properties, or low price are more important than performance. Non-MIMO device
  • NanoBridge M: Provides incredible price/performance for medium distance links
  • PowerBridge M: State of the art device for medium-long distances. Double the RAM of other products for additional performance
  • Long distance (15+ km)
  • Rocket M w/Dish: Industry-standard for long distance high performance links. Up to 150Mbps TCP/IP throughput. Distances of 100+ km
  • High Performance Backhaul
  • airFiber 24: For extreme performance, the airFiber 24 product delivers up to 1.4Gbps of actual throughput at distances of 5+ km in the 24GHz band. However, under certain circumstances you can use it up to 13 km.

PtMP

PtMP performance depends on both sides of the link, i.e. if you want to reach long distances, you must choose the right Base Station AND the right CPE for each case.

Base Station

Usually located on the top of a tower, building or mast. The height will determine maximum coverage. When planning the Base Station, it's usually ideal to plan for an antenna with the smallest coverage that still covers the desired area. Antennas with a wider beamwidth, covering a wider zone reaching more stations, may be more susceptible to interference, resulting in decreased scalability and performance.

PtMp link


  • Low capacity and short distance Base Station (ideal for starters in areas with low interference)
  • Rocket M with RocketOMNI antenna: up to 60+ concurrent stations when all devices are airMAX capable. Highly susceptible to interference, recommended only for moderately/highly rural areas
  • High Capacity & High Performance Base Stations
  • Rocket M with Standard Sector Antenna: Industry-standard for Base Stations. Four 90° or three 120° antennas for 360° coverage. 300+ stations per Base Station/AP Tower
  • Rocket M-Titanium and Titanium Sector Antennas: New, high-performance solution for high density areas. Variable beamwidth (60-120°) antennas for scalable growth. 500+ stations per Base Station/AP Cell Tower. Superior isolation and airSync technology to avoid co-location interference

Customer Premise Equipment (CPE)

  • Short distance (0-3 km)
  • Loco M: Lowest cost option, short range, and least directive CPE
  • Nano M: Slightly greater range than the Loco M and more directive
  • Medium distance (3-7 km)
  • airGrid M: Low cost CPE, very narrow beamwidth, but not MIMO (half the performance of NanoBridge M)
  • NanoBridge M: Highly directive CPE, better range and lower noise.
  • Long distance
  • PowerBridge M: Higher power device, highly directive CPE, better range and lower noise, aesthetically pleasing compared to dish
  • Rocket M with RocketDish: Best performing option, higher cost than integrated designs, can be unsightly as a CPE

Note! It is fine to use higher performing devices for shorter distances. As an example, the NanoBridge M will likely outperform the Loco M for short range links due to the antenna properties.


Hotspots

The UniFi product line is recommended for hotspot scenarios. It offers centralized management, guest portals, bandwidth limits, multiple SSIDs, vouchers and many other features.

Frequency Options

Unlicensed frequencies

Each frequency has different characteristics due to physics and utilization. Lower frequencies have better propagation characteristics than higher frequencies, and may work better in environments where Line of Sight is obstructed (trees, etc.). However, these bands may also have higher levels of noise and interference, so it's important to select the frequency that works best in your situation.

900MHz (M900)

Advantages and Disadvantages

  • + Better tolerance for trees and small obstacles vs. higher frequencies.
  • - Usually higher noise levels
  • - Only 26MHz bandwidth
  • - Not unlicensed worldwide.

2.4GHz (M2)

Advantages and Disadvantages

  • + Worldwide unlicensed
  • - Only three non-overlapping 20MHz channels (1, 6, 11)
  • - It’s a very crowded band; there’s a lot of interference from cordless phones, SOHO Wireless Router, other WISPs, etc…
  • - 40MHz channels not recommended


3.x GHz (M3-M365)

Advantages and Disadvantages

  • + 300MHz bandwidth in countries where 3.4-3.7GHz band is available
  • + Noise-free in most areas
  • - Only 25MHz bandwidth in countries where 3.65GHz can be used.
  • - Requires license.

5 GHz (M5)

Advantages and Disadvantages

  • + Worldwide unlicensed
  • + Higher EIRP limits, allow higher gain antennas, and long distance links
  • + Large amounts of spectrum available, easier to co-locate nearby devices
  • - Weaker propagation vs. lower frequencies when obstacles are present (trees, walls, etc.)

10 GHz (M10)

Advantages and disadvantages

  • + Noise-free in most cases, very useful when 5.8GHz band is crowded.
  • + Very small Fresnel zone
  • - Only available in a few areas
  • - Licensed band
  • - Requires perfectly clear Line of Sight


Antenna Options

Directional antenna


High gain antennas play an important role in hi-performance outdoor wireless for a couple of reasons.

  1. They provide hi-gain amplification of the signal power resulting in higher signals and better link quality.
  2. They are highly directional which gives them spatial filtering characteristics, which can help to block noise – especially important in noisy environments.


Antennas fall into these categories:

  • Yagi: Directive, used for PTP and CPE applications. Frequently used in low frequencies, such as 900MHz, due to size
  • Grid: Directive, used for PTP and CPE applications. Great wind-loading properties. However, this type only works in one polarity (1x1), so lower performance than 2x2 antennas (Dish, Panel, etc)
  • Panel:Directive, used for PTP and CPE applications. Compact design is very attractive in situations where dishes are not preferred.
  • Dish: Most Directive, highest performing airMAX antennas for PTP applications. Usually larger and heavier.
  • Omni: Provides 360 degrees of horizontal coverage (omni-directional). Ideal for low capacity and wide-coverage AP / Base Station applications)
  • Sector: Ideal choice for high performance Base Stations. Offer higher gain and directivity than omnidirectional antennas. Usually offered in 60, 90, or 120 degree options.


Link Planning

Distance is one important factor when you consider link planning. However, there are also other important factors, such as Fresnel zone and Fade Margin.

The Fresnel zone: The Fresnel zone defines the area surrounding a line of sight link that must be free of obstructions that might cause out of phase reflections that can significantly degrade signal quality. The below image shows an example of an obstruction that is within the Fresnel zone of the link:


airLink: In many cases, calculating the Fresnel zone is a complicated task, since it’s not a simple ‘Line of Sight’ from one end of the link to the other. Therefore, Ubiquiti developed airLink (www.ubnt.com/airlink), a link budget software which allows installers to estimate the link viability, providing important information such as Fresnel zone clearance, link distance and estimated signal strength and performance.

airView: A site survey should be conducted on-site to examine environmental noise of an area. The easiest way to analyze spectrum interference is using airView, you can find a step-by-step guide here. In case the entire spectrum is very crowded you should consider using a different band. For example, if 2.4GHz band is crowded, it may would be a good idea moving to 5.8GHz or 3.65GHz band.

Fade Margin: Signals strength may fluctuate with environmental changes (change in season, rain patterns, etc.). Therefore, operators usually take into account a 15dB “fade margin”, in order to guarantee a high uptime rate and more robust link.

Best Practices for Outdoor Wireless

  • ALWAYS use shielded cable (like TOUGHCable PRO & CARRIER Grade) and properly ground all outdoor radios to avoid ESD damage and long-term performance degradation.
  • Alignment your antennas properly, make sure both polarities (or chains) have balanced signal.
  • Enable airMAX for superb performance—it’s based on a proprietary TDMA protocol which results in:
  • Elimination of hidden-nodes
  • Increased throughput, low latency across networks
  • Highly scalable networks with multiple stations associated.
  • Secure your devices
  • Enable HTTPS
  • Change default credentials
  • Use the latest firmware available

WISP Information