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Wireless Frequency Spectrum

Ideal for Wireless Link or WISP Design

Choosing the right type of wireless frequency spectrum is extremely important when designing your Wireless Links. Your choice of wireless frequency can alter the attributes and abilities of your network. Each spectrum has its advantages and disadvantages, by understanding these you can better determine where to deploy certain frequency equipment in your wireless solution.

Licensed vs. Non-licensed

The government, through the FCC (federal communications commission) has set rules and guidelines for the use of radio equipment to better control wireless frequency "traffic". The more wireless "traffic" the less effective wireless signal transmissions become. In order to avoid most radio interference, the FCC has allowed businesses to purchase allotments of frequency spectrum which they can broadcast on without any outside interference from others using the same frequency. This is the ideal situation for wireless networking; however, this frequency "real estate" does not come cheap. It is almost financially impossible for most individuals to license private frequency spectrum.

This is why we steer the vast majority of WISP entrepreneurs or any individual away from licensed frequency bands. Non-licensed frequency is a vastly cheaper and quicker platform for building your wireless solution.

Despite the heavy use of the license free spectrum, it is still an excellent platform for building cheap, fast and reliable wireless networks.

License Free

The FCC has provided several license-free bands for the wireless community to utilize (ISM & U-NII bands). They are:

• 900 MHz: 902-928 MHz
• 2.4 GHz: 2403-2483 MHz
• 5 GHz: 5725-5850 MHz, 5150-5250 MHz, 5250-5350 MHz, 5725-5825 MHz

Frequency Attributes

Wireless signals have changing attributes as frequency, wavelength, amplitude and several other key features change.

When Frequency Increases:

• Becomes easier to attenuate (can’t travel as easily through obstacles i.e foliage, walls etc).
• Able to transmit more bandwidth.

When Frequency Increases:

• More effective when transmitting through obstacles-less attenuation (when compared to higher frequency signals).
• Can’t transmit as much bandwidth as higher frequency signals.
• The lower frequency bands (i.e 900 MHz, 2.4 MHz) are much more congested, with more wireless "traffic" than the higher frequency- 5 GHz bands.

900 MHz vs 2.4 GHz vs 5 GHz License Free Wireless Frequencies

	900 MHz	2.4 GHz	5 GHz
Popularity	Not widely used in WISP Networks	Widely Used	Becoming Widely Used
Speed	Lowest Throughput	High Throughput	High Throughput
Cost	Inexpensive	Inexpensive	Inexpensive
Frequency	Crowded, Good Nlos Usage	Crowded	Uncrowded
Range	Weak Range	Average Range	Average Range
Application	Mesh, short ptmp with lots of obstacles	Mesh, ptp, ptmp	Backhaul, ptp, ptmp

802.11 A vs B vs G Wireless Technology Comparison Chart

	802.11 b	802.11 a	802.11 g
Popularity	Widely adopted readily available	New technology	Rapid growth
Speed	Up to 11 Mbps	Up to 54 Mbps	Up to 54 Mbps
Cost	Inexpensive	More expensive	Inexpensive
Frequency	Crowded band	Uncrowded - 5GHz	Crowded band
Range	Good Range, depend on equip & obstacles	Shorter Range, depend on equip & obstacles	Good Range, depend on equip & obstacles
Public Access	Lots of access: hotspot, public Wi-Fi, etc	Limited	Lots of access: hotspot, public Wi-Fi, etc
Compatibility	Widest adoption	Incompatible w/ 802.11 b/g	Interoperates w/ 802.11 b