Writings of Mass Deduction

Wireless frequency bands are a bit of a mystery to many wireless users.  Let’s see what we can demystify, however.  In general terms, you can break wireless spectrum down into two types:  low-band and high-band, and each has an advantage.

Lower frequency number travel further from the site, and penetrate buildings better.  Common low-band frequencies in North/CentralSouth America are 600MHz, 700MHz, and 850MHz, and a common one in the rest of the world is 900MHz.

Higher frequency numbers generally offer greater wireless capacity, meaning more customers can use it simultaneously and it may offer higher speeds.  Common high-band frequencies in use in North America are 1700/2100MHz and 1900MHz, a common one in the rest of the world is 1800MHz, and a common one globally is 2600MHz.

But don’t some of these frequency bands have special names as well, such as “AWS”?  Yes, see the notes at the bottom with regard to details on the different blocks.  If you just want to know what the names correspond to, then know that:

CLR = 800MHz (AKA 850MHz, AKA Band 5)

PCS = 1900MHz (AKA Band 2)

AWS = 1700/2100MHz (AKA AWS-1, AKA Band 4)

BRS = 2600MHz (AKA 2500MHz, AKA Band 7)

MBS = 700MHz

In an ideal world, a wireless carrier would generally prefer to have a mix of low and high-band frequencies.  Low-band spectrum can be rapidly deployed over a wide area at lower cost because fewer cell sites are needed.  This is what was done in the early days of cellular phones, where all the sites were 800MHz.  Initially, cellular phones were analogue (rather than digital) and used for nothing much other than phone calls.  They were insecure and relatively few people could be fit into the frequency band.

As more people started using wireless phones leading to congestion in the airwaves, and as other uses for the technology (such as text messaging and data) began to be envisioned, the first high-band was auctioned off and “Digital PCS” was born.  The new 1900MHz frequency required approximately four times as many sites to cover the same area, but this dramatically increased capacity.  New digital technologies such as GSM and CDMA started getting a lot more phone calls into the same amount of wireless space.  For the first time, people had to start wondering about what frequencies their phone supported, however, a problem that would become worse over time.  Suddenly there were who, if they had a complaint about a carrier’s service, might benefit from a new people complaining about the quality of a wireless carrier’s service, without realizing that if they changed their device to one that supported a greater number of their carrier’s frequencies that they would likely enjoy improved service (perhaps less congestion, perhaps stronger signal).  We’ve been in that state ever since, as new frequencies gradually get rolled out.

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MORE DETAILS ON COMMON FREQUENCY BANDS

Most frequency bands have a three-letter nickname.  Some of them are rarely called by the nickname (such as 850MHz), others are commonly called by their nickname (such as “AWS”), and this often causes confusion.  If you’re trying to decipher a post on an online wireless forum, you’d ideally be conversant in their nicknames as well.  I’ll discuss each one that has a nickname in their order of appearance in Canada:

• CLR = 800MHz (AKA 850MHz, AKA Band 5).  CLR is meant to be short for the word “cellular”.  This was the first wireless phone frequency band for the public in Canada, the U.S., and much of the Americas, all the way back to the original analogue “brick” cellular phones.  Cellular, BTW, refers to the way the network is laid out in “cells”, each cell centred around a cell site.

• PCS = 1900MHz (AKA Band 2).  PCS stands for Personal Communications Services.  When you started seeing ads in the late ’90s for “digital” phones, this was the band they were all using.  Rogers in Canada even branded their new digital network under the name “Digital PCS”.

• AWS = 1700/2100MHz (AKA AWS-1, AKA Band 4).  AWS stands for Advanced Wireless Services.  This was the first band allocated in Canada when 4G/LTE came out, and is also used for LTE by most American carriers (some as a primary band, some as a secondary band).  Why is both 1700MHz and 2100MHz?  Well, because most frequency bands are “paired” (though some of the newer ones aren’t more on that later).  In the case of PCS (for example), the tower listens for the phone (the uplink) in the 1850-1910MHz range (depending on which slice of PCS your local carrier has, as multiple carriers divvy up the band between them in an area).  The phone listens for the cell site in the upper end of the range, from 1930-1990MHz (the downlink).  For simplicity’s sake, the band is commonly referred to as 1900MHz, however.  AWS is the same, except the tower listens for the phone in the lower 1700MHz range, and the phone listens for the tower in the 2100MHz range.  In other countries they rolled out 1700MHz all on its own because 2100MHz was already in use there, so in North America we went a very different route which increased capacity but created incompatibility.

• BRS = 2600MHz (AKA 2500MHz, AKA Band 7).  BRS stands for Broadband Radio Services.  The actual frequency band takes up much of the range between 2500-2700Mhz.  This band is in use in parts of Africa, and in much of Europe, Asia, and South America.  As for North America, however, it’s commonly found in big cities in Canada but is not in use in the United States at all.  This band is great for phone importers, as almost all modern phones support this band, even those that support no other LTE bands in use in Canada.  Why is this not in use in the United States?  The U.S. distributed this band as a nearly (but not quite) identical band called EBS, or Educational Broadband Service.  It passed through different hands before ending up with Sprint, who launched band 41 LTE.  Sprint is known for using oddball bands in the U.S., and for having strict policies about activating handsets on their network that they didn’t sell (or in some cases handsets that they did sell, if you’re trying to activate a Sprint-branded phone on one of their prepaid brands such as Boost Mobile), so they’re likely unconcerned with people being able to activate band 7 handsets on their network.

• MBS = 700MHz.  MBS stands for Mobile Broadband Service.  This was the main LTE frequency for AT&T in the U.S. when they first launched it, and is the main low-band LTE frequency for both Canada and the U.S.  Unlike most other LTE frequencies where there’s one band number for the whole thing, MBS is broken down into many competing bands depending on the section, or “block”, of the frequency in question.  For example, the lowest chunk of MBS is 700Mhz blocks A, B, and C, which has predominantly been rolled out in the U.S. by T-Mobile.  Block A interferes with television signals in some markets, so T-Mobile has had to negotiate with TV stations doing over-the-air broadcasts on Channel 51 to relocate to other channels to roll out this service.  Because of this interference issue, AT&T convinced regulators to create a new band, Band 17, that is a sub-set of Band 12 with block A removed.  Band 17 is the band they initially offered LTE service on.  In Canada, Rogers got much of the country’s Blocks A and B, and chose to launch half of it as Band 12 (the only way to utilize Block A at all) and Band 17 (due to many more handsets supporting band 17 at the time).  Down the road they could conceivably reallocate their band 17 with their band 12, in areas where there’s no Channel 51 interference.

• AWS-3 = 1700/2100MHz.  Slightly higher up the 1700MHz band for the uplink and 2100MHz for the downlink than AWS-1, sits AWS-3.  What happened to AWS-2, you ask?  It’s actually an extension of PCS.  PCS was broken down into blocks A-F, and the first extension of PCS was called PCS-G.  AWS-2 can also be thought of as PCS-H, since it adds an H block alongside PCS.