Understanding 3G and 4G... Or Not. A Semi-Humorous Waltz Through Jargon Land

Okay, so now you understand 3G!

The screen capture above is taken from the Wikipedia article about 3G mobile phone technology. Recently I have been attempting to really understand with 3G technology is, and what 4G technology will be.

It started with a friendly visit to my AT&T store, where I told the salesman that I was planning to switch to Verizon as soon as the iPhone was available on that network. What ensued was a 30 minute debate about phone network technologies. While some of the things he said didn't make sense, he was dramatically better informed than I expected. I said that I understood that Verizon would be using the new 700 MHz bands for their 4g and would therefore get good building penetration. He said AT&T already uses 850Mhz and has good penetration. (Hard to know what frequencies the phones are actually using at any one time; they also run at 1900Mhz which doesn't penetrate so well)

I can't remember all the details of the conversation, but it led me craving some real facts. And of course, when you search for real facts, you get charts like the one above.

Sprint is claiming 4G service with their WiMax service. The AT&T guy said that WiMax is like a fancy hotspot. If you connect to it, you'll get fast speeds, but you better not move away from the cell, or you'll drop back to the 3G network. True? I don't know. But I'm not used to being so fuzzy on a technology so central to our daily lives.

This article:  "Will the real 4G please stand up?" doesn't help much, other than to say that there are a bunch of competing technologies for "4G" and each has its alphabet soup: LTE, HSPA+

Sometimes you can get clearer information from the hardware vendors themselves. A Google search for "4g manufacturers" got me this result, just for WiMax.

A search for "LTE Manufacturers" got me the page above. So, let's say I have a little local network and I want to buy a nice 4G network infrastructure setup. I should be able to search for that and get some answers? Not easy. Finally a search for "Ericson 4G Network Hardware" got me this:  Okay, that's good. A real vendor, and a real network. Let's see what I can find out about the hardware.

Apparantly, Alcatel Lucent doesn't support Amazon Prime. It's not easy to even figure out where to look. But I am undaunted.

Uh...Where's my shiny overview of 4G technology, complete with some nice screen shots of some honkin' rack-mounted hardware?

Oh wait, now things are getting clearer. I hadn't realized the important role that EPC, MME, PCRF, SGW and PGW would play on the Converged Backbone Transport IP/MPLS.

Maybe Motorola might put things more simply. Hey, look above. That's progress. Some rack mounted stuff. Some brochures and some articles. I'm writing this in real time, so you'll discover with me. Where to start? How about LTE Technical White Paper

Of course! But at least Motorola's document has large type and nice illustrations.

And they do explain some of the three-letter acronyms from the Alcatel document. Let's see if some of the rack-mounted hardware gets us anywhere.

Okay, now we're at the hardware store. No prices shown, but let's check out the WBR 700 Series LTE BCU3 FDD & TDD Baseband Controller Unit.

Okay, this looks like some real hardware, with some good stuff on the right.

From the link: (A PDF)

Okay, I'm getting the idea that this stuff isn't aimed at me. If you're not a network engineer, its going to be hard to jump in and figure anything out.

From a PDF

So, is there anyone out there who can explain this stuff in English? Anyone know some articles that do that? If you have any information, please comment below!

7 responses
I'm reading this on a 4G connection from Sprint. It's still not any clearer :-).
I don't think there is any such thing as 4G or 3G. It's just marketing slang to group technologies by basic "speed". From the looks of LTE when it is actually available it is going to be much faster that WIMAX.
Jack - True. In fact, I think the organizing body that controls "official" 4G says it has to have 100Mbit speeds. (At least theoretical speed). Still, the nerd in me would like to learn SOMETHING about how all this works, and what makes different standards better or worse. Does WiMax have handoffs? Does At&t reallly use 850Mhz? How do you know? Will Verizon 4G really stay only at 700Mhz, and thereby have awesome building penetration all the time?
you aren't considering the magic elves option.
I actually know someone at sprint in the engineering side i could ask for you if there is in fact a blog or cheat sheet to help you find some info. I have the sprint wimax and it is really sweet. Don't even have a wired internet option in my house anymore. TV from OTA or Hulu. I'm totally wire free now. (except at work of course)
Hook me up! I need truth. Engineers know the truth and usually speak it. 
Bill, There are (at least) two answers, one focused on technology and one based on ITU definitions.

The technology answer is roughly:
3G -- uses CDMA modulation and a hybrid core network that treats voice and data separately,
4G -- uses OFDMA modulation (optionally with SC-FDMA on the uplink) and an All-IP core network.
Note that while OFDMA and SC-FDMA sound different, they use extremely similar computational structures in the silicon.

The ITU answer is more political. Until they began to cave into marketing hype in a December 6th press release, the ITU defined 4G as a downlink capable of 100 Mbps to a moving device (auto & train speeds) and 1 Gbps to a fixed or slowly moving device (pedestrian speeds). The two candidate systems for 4G (prior to 6 Dec 2010) were LTE-Advanced and WiMAX 802.16m -- both systems that are still in development and likely years away from widespread deployment.

After their press release of a few weeks ago, things got a lot muddier... See:

The good thing about your information is that it is explicit enough for students to grasp. Thanks for your efforts in spreading academic knowledge.

dissertation | writing a dissertation | thesis dissertation

1 visitor upvoted this post.