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Wireless Frequencies and Nextiva Wireless Devices PDF Print E-mail

The unlicensed 2.4 GHz and 5 GHz wireless bands and the licensed 4.9 GHz US and Canada public safety bands

Radio Frequency

RF (radio frequency) communications work by creating electromagnetic waves at a source and then receiving those electromagnetic waves at a particular destination. The electromagnetic waves travel through the air at almost the speed of light. The wavelength of an electromagnetic signal is inversely proportional to the frequency: that is, the higher the frequency, the shorter the wavelength.

Frequency is measured in hertz (cycles per second), and radio frequencies are measured in kilohertz (KHz or thousands of cycles per second), megahertz (MHz or millions of cycles per second) and gigahertz (GHz or billions of cycles per second). Since higher frequencies result in shorter wavelengths, the wavelength of a 900 MHz device is longer than that of a 2.4 GHz device.

2.4 GHz Wireless Band (Unlicensed)

The 2.4 GHz band has 14 frequency channels, but only 11 are permitted for unlicensed use by the FCC in the US. Each channel extends 11 MHz on each side of the center frequency. Most importantly, the channels overlap. The table below shows the frequency channels that are available in the 2.4 GHz band.

Channel Frequency (MHz) Location
To the extent that channels overlap, they interfere with each other and reduce available bandwidth. For installations that require multiple access points, three access points using channels 1, 6, and 11 have no overlap. Larger installations must be properly deployed to minimize interference, or a frequency band with more available channels must be used.

Note that the 2.4 GHz frequency band is limited by the number of non-interfering channels available, and most wireless office telephones and networking equipment use the same frequency band. This increases the risk of potential interference and can reduce available throughput for transmitting video. Consequently, 2.4 GHz equipment should be used only when there is little risk of interference from other 2.4 GHz equipment being used in the area.
1 2412 North America, Europe, Japan
2 2417 North America, Europe, Japan
3 2422 North America, Europe, Japan
4 2427 North America, Europe, Japan
5 2432 North America, Europe, Japan
6 2437 North America, Europe, Japan
7 2442 North America, Europe, Japan
8 2447 North America, Europe, Japan
9 2452 North America, Europe, Japan
10 2457 North America, Europe, Japan
11 2462 North America, Europe, Japan
12 2467 Europe, Japan
13 2472 Europe, Japan
14 2484 Japan Only

5 GHz Wireless Band (Unlicensed)

The 5 GHz band is actually four frequency bands: 5.1 GHz, 5.3 GHz, 5.4 GHz, and 5.8 GHz. The 5 GHz band has a total of 24 channels with 20 MHz bandwidth available. Five of these can be used outdoors without requiring DFS and TPC. Unlike the 2.4 GHz band, the five channels are non-overlapping, so all five channels have the potential to be used in a single wireless system.

The table below shows the frequency channels that are available in the 5 GHz bands.

Channel Frequency (GHz) Location
36 5.180 Indoor Only
40 5.200 Indoor Only
44 5.220 Indoor Only
48 5.240 Indoor Only
52 5.260 DFS required
56 5.280 DFS required
60 5.300 DFS required
64 5.320 DFS required
100 5.500 DFS required
104 5.520 DFS required
108 5.540 DFS required
112 5.560 DFS required
116 5.580 DFS required
120 5.600 DFS required
124 5.620 DFS required
128 5.640 DFS required
132 5.660 DFS required
136 5.680 DFS required
140 5.700 DFS required
149 5.745 North America
153 5.765 North America
157 5.785 North America
161 5.805 North America
165 5.825 North America

4.9 GHz US Public Safety Band (Licensed)

The US Federal Communications Commission (FCC) allotment of 50 MHz of spectrum in the 4.9 GHz band permits public safety agencies to implement on-scene wireless networks for streaming video, rapid Internet, database access, and the transfer of large files, such as maps, building layouts, medical files, and missing person images. It also allows public safety agencies to establish temporary fixed links to support surveillance operations. This allocation gives every jurisdiction in the country access to the spectrum for interoperable broadband communications. Specific FCC rules are covered in Subpart Y in 47CFR part 90 of the FCC regulations.

A 4.9 GHz band license gives the licensee authority to operate on an authorized channel in this band within the applicant’s jurisdiction (city, county, state). A license allows use of base stations and mobile devices, such as laptops and PDAs.

The 4.9 GHz band must be shared by all licensees in an area, with coordinated usage and channel arrangements. Generally, this is not an issue since few 4.9 GHz transmitters exist and few transmit continuously. Licenses are granted for a period of 10 years.

Who is eligible to apply for a 4.9 GHz license? All US state and local government entities, private companies sponsored by a government entity (such as private ambulance services), and any organization with critical infrastructure (power companies, pipelines, etc.) that provides public safety services for the protection of life, health, or property. They may apply on the FCC website under the ULS section and must pay a $50 filing fee. Those organizations that do not meet the eligibility requirements, but support public safety, may negotiate with the license holder for sharing agreements.

Increasing the Number of Channels with Channel Fragmentation

Since the 4.9 GHz band is limited to 50 MHz, only 2 standard, independent channels of 20 MHz are available in this band. Channel fragmentation in the 4.9 GHz band has been added to allow more than two systems to operate in the same area. With channel fragmentation, a licensee can select a channel bandwidth of 20 MHz (standard channel bandwidth currently supported), 10 MHz, or 5 MHz. The 10 MHz channel bandwidth allows for four independent channels, and 5 MHz allows 10 independent channels. The 5 and 10 MHz channel bandwidths are available only in the 4.9 GHz band.

Nextiva Wireless Edge Devices

All Nextiva wireless edge devices are designed for high performance on the unlicensed 2.4 and 5 GHz wireless bands and the licensed 4.9 GHZ US public safety band.

S4100 Wireless video encoder/transmitter and decoder/receiver pair for point-to-point wireless applications, delivering MPEG-4 based video up to 4CIF/30 fps
S4200 Wireless video encoder/transmitter for point-to-multipoint wireless applications, delivering dual-stream, MPEG-4 based video up to 4CIF/30 fps, with optional on-board analytics
S4300 Wireless access point for aggregating traffc from multiple S4200 devices in point-to-multipoint applications
S4300-BR Two units that act as a wireless bridge in point-to-point or point-to-multipoint applications
S4300-RP Wireless repeater for retransmitting signals from Nextiva wireless devices to a wired LAN in point-to-point or point-to-multipoint applications