Last Post: February 7, 2008:
What should we call the new 255 MHz wide U-NII band?
I think naming the several U-NII bands should be done by the FCC. Within USA territories it is their spectrum and their rules.
Looking over the FCC documents I get these impressions:
1. The FCC uses the compound acronym U-NII and not UNII.
2. The FCC uses absolute frequency ranges for bands and does not otherwise name the bands.
3. The FCC uses bands to define contiguous spectrum and sometimes bands within those bands to apply rules.
4. The FCC up to now has always defined two contiguous U-NII spectrum bands and three sets of U-NII rules.
5. The FCC 2004 amendments enlarged the second of the two spectrum bands and applied the second of the three rule sets to the additional spectrum.
Naming the bands I, II, III, first, second, third, lower, middle, upper, although never sanctioned by the FCC nonetheless used to be convenient. Now the "three band" fiction is confusing. Which of the several bands was extended in 2004, the second or the third?
When the FCC next changes the U-NII spectrum and/or the U-NII rules, the new bands will have absolute frequency ranges that are likely to further confuse any devotion given now to the "three band" fiction.
If it takes four bands to properly describe the interaction of U-NII spectrum and U-NII rules then lets both call them out by their frequency boundaries when precision calls for it and by their position relative to each other -- first, second, third, fourth -- when convenient. In both cases know also that the first and second bands are contiguous, the third and fourth bands are contiguous, and the second and third bands share a set of rules.
Band : Frequency : Width : Power
1st U-NII band : 5.15-5.25 GHz : 100 MHz : "50 mW" rules
2nd U-NII band : 5.25-5.35 GHz : 100 MHz : "250 mW" rules
3rd U-NII band : 5.47-5.725 GHz : 255 MHz : "250 mW" rules
4th U-NII band : 5.725-5.825 GHz : 100 MHz : "1 W" rules
I hope this helps. Thanks. /criss
"FCC 04-165 Report and Order, Adopted: July 8, 2004
"???¡ì 15.403 Definitions.
"(s) U-NII devices. Intentional radiators operating in the frequency bands 5.15 - 5.35 GHz and 5.470 - 5.825 GHz that use wideband digital modulation techniques and provide a wide array of high data rate mobile and fixed communications for individuals, businesses, and institutions.
"???¡ì 15.407 General technical requirements.
"(a) Power limits:
"(1) For the band 5.15-5.25 GHz, the maximum conducted output power over the frequency band of operation shall not exceed the lesser of 50 mW or ....
"(2) For the 5.25-5.35 GHz and 5.47-5.725 GHz bands, the maximum conducted output power over the frequency bands of operation shall not exceed the lesser of 250 mW or ....
"(3) For the band 5.725-5.825 GHz, the maximum conducted output power over the frequency band of operation shall not exceed the lesser of 1 W or ...."
After consulting the entire CWNE Roundtable for this purpose, we have reached a consensus that the naming of the bands will be
Band : CWNP name : Often called:
5.15 ?¡é?€?¡° 5.25 GHz : UNII-1 : Lower UNII
5.25 ?¡é?€?¡° 5.35 GHz : UNII-2 : Middle UNII
5.470 ?¡é?€?¡° 5.725 GHz : UNII-2E : UNII-2 Extended
5.725 ?¡é?€?¡° 5.825 GHz : UNII-3 : Upper UNII
I agree, as have others, that calling a band by its freq range is the most accurate way to address it, but we need user-friendly naming conventions as well. We can teach in our classes, put in our books, etc all of the common naming, but when it comes to exams, we have to have one that's consistently used and documented properly. That's what is above.
Question 1: How many FCC U-NII bands are there?
A) One - the 5 GHz band
B) Two - a lower band and an upper band
C) Three - a lower band, an extended middle band, and an upper band
D) Four - a lower band, a middle band, an upper band, and an extended middle band
Explanation: Ever since the FCC defined the Unlicensed National Information Infrastructure (U-NII), there have been two discontinuous U-NII bands. The original two bands were 200 MHz and 100 MHz wide. In 2004 the second of the two bands was extended by 255 MHz. Since then the two bands occupy 5.15-5.35 GHz and 5.47-5.825 GHz.
A is incorrect because, although the IEEE 802.11 OFDM and HT PHYs are said to operate in the "5 GHz" band, the FCC does not define U-NII in this manner.
C is incorrect because, although the IEEE and vendors for a time spoke of three power output rules applying to three distinct bands, it was the last of these bands that was extended by 255 MHz in 2004.
D is incorrect because while the three power output rules do apply to four parts of two bands, it makes little sense to call the four bands by these tortured names especially when it was the "upper" band that was extended by 255 MHz.
The IEEE 802.11a-1999 amendment, section 18.104.22.168.3, refers to lower, middle, and upper U-NII bands, but this language is removed from the pending revision of the IEEE 802.11 base document where seven (!) bands are defined (with more pending in amendments to follow such as 5.9 GHz for vehicular WLANs).
Question 2: How many FCC U-NII output power rules are there?
Explanation: Ever since the FCC defined the Unlicensed National Information Infrastructure (U-NII), there have been three U-NII output power rules. In 2004 255 MHz was added to the original 300 MHz U-NII spectrum and the second of the existing three rules was applied to the additional spectrum.
22.214.171.124.1 Operating frequency range
The OFDM PHY shall operate in the 5 GHz band, as allocated by a regulatory body in its operational region. Spectrum allocation in the 5 GHz band is subject to authorities responsible for geographic-specific regulatory domains (e.g., global, regional, and national). The particular channelization to be used for this standard is dependent on such allocation, as well as the associated regulations for use of the allocations. These regulations are subject to revision, or may be superseded.
In some regulatory domains, several frequency bands may be available for OFDM PHY-based wireless LANs. These bands may be contiguous or not, and different regulatory limits may be applicable. A compliant OFDM PHY shall support at least one frequency band in at least one regulatory domain. The support of specific regulatory domains, and bands within the domains, shall be indicated by PLME attributes dot11 RegDomainsSupported and dot11 FrequencyBandsSupported.
The set of valid operating channel numbers by regulatory domain is defined in Annex J.
SYNTAX INTEGER (1..127)
"The capability of the OFDM PHY implementation to operate in the 4.9
GHz and 5 GHz bands. Coded as an integer value with bit 0 LSB as
bit 0 .. capable of operating in the 5.15-5.25 GHz band
bit 1 .. capable of operating in the 5.25-5.35 GHz band
bit 2 .. capable of operating in the 5.725-5.825 GHz band
bit 3 .. capable of operating in the 5.47-5.725 GHz band
bit 4 .. capable of operating in the lower Japanese (5.15-5.25 GHz) band
bit 5 .. capable of operating in the 5.03-5.091 GHz band
bit 6 .. capable of operating in the 4.94-4.99 GHz band
For example, for an implementation capable of operating in the
5.15-5.35 GHz bands this attribute would take
the value 3."
I hope this helps end the era of lower/middle/upper/extended. Thanks. /criss
For me answer D is correct. as long as i understanding and i am preparing for CWNA , there were three bands, lower, middle and upper and devinator just said there will be a extended one, so why answer is B ?
Luckly this will not be covered when i sit exam in July...
let me know...
The FCC created two U-NII bands and three U-NII output power rules. The two halves of the first band used the first two rules, and the second band used the third rule.
The IEEE in 1999 described these as three bands and three rules, calling the bands lower, middle, and upper. No one much cared that the first two of these bands were contiguous.
The FCC expanded the second U-NII band in 2004, but applied the second rule to the additional spectrum. Now both FCC U-NII bands had two parts governed by separate rules for a total of four parts -- two U-NII bands, three U-NII rules, and four pairs of U-NII sub-bands and rules.
The IEEE is poised to retract their lower, middle, and upper terminology and describe each of four pairs of U-NII sub-bands and U-NII rules as a distinct frequency band but with no name. By 2008 there will be no IEEE 802.11 lower, middle, upper, nor extended, bands. Apparently the IEEE found maintaining names for these bands to be not worth the trouble and confusion.
If neither the FCC that owns U-NII, nor the IEEE that owns 802.11, names these bands, why should anyone else, especially with outdated terminology fit for three sub-bands rather than four, and confusion about just what was "extended"?
I hope this helps. Thanks. /criss
It helped indeed but the subject is rather confusing...another confusion that i see regards the output powers, in the books it was 40mw for lower bands, 200mw for middle bands and 800mw for upper bands.
and i took a look and they increased a little, is that correct ?
Notice that the FCC says "the lesser of" a simple number or .... I left out the rest of the FCC formula. Apparently the IEEE 802.11 committee applied the FCC formula and found that in practical terms the best the IEEE could do was about 80% of the simple number. Hence each set of numbers is correct in its own context.
FCC limits : IEEE limits
lesser of 50 mW or ... : 40 mW
lesser of 250 mW or ... : 200 mW
lesser of 1 W or ... : 800 mW
I hope this helps. Thanks. /criss
I vote we rename the US unlicensed frequency bands from 900 MHz, 2.4 GHz and 5 GHz to lower, middle, and upper UFBs. ;-)
Does one need to memorize these UNII bands for the CWNA exam?
That would be a very good thing, yes.