WiMax Is Finally Coming — Here's How It Performs

GMGruman writes "Carriers have promised WiMax networks for years. But will they deliver the goods, or be slow like many early 3G networks or patchy in coverage like the metro Wi-Fi attempts in most cities? This hands-on review looks at a nearly-WiMax deployment (technically, OFDM) in Reno, testing its speeds and reach, as a measure of what Sprint and Clearwire will deliver in their joint WiMax rollouts starting next month. The good news is that this time, the carrier promises look to be delivered on."

Comments

So a nearly-wimax review of something else?

[Anonymous Coward]

So, this is a review of WIMAX, except it's not of WIMAX it's of something else? Can we review Wifi next to see how T-Mobile's 3G service is in my area too?

Re:So a nearly-wimax review of something else?

[Ctrl-Z]

I know you're a coward, but did you actually read the article? I can understand how you might be confused, but the word "WiMax" appears about 25 times. Why do you think this isn't a review of WiMax?

Re:So a nearly-wimax review of something else?

[santiagoanders]

From TFA:

"To be completely accurate, the Clearwire service is not officially WiMax but OFDM, the underlying technology behind the WiMax standard. Clearwire deployed the Reno network before the WiMax standard was final, but it is practically the same technology."

Re:So a nearly-wimax review of something else?

[clang_jangle]

Maybe he actually RTFA and saw:

To be completely accurate, the Clearwire service is not officially WiMax but OFDM, the underlying technology behind the WiMax standard. Clearwire deployed the Reno network before the WiMax standard was final, but it is practically the same technology.

"Practically the same technology"?! Let's call things what they are, please... This "review" is of a wimax-like network; the "test" may or may not be indicative of any future wimax implementation.

Re:So a nearly-wimax review of something else?

[squiggleslash]

Exactly. WiMAX's up and coming rival is GSM/UMTS LTE, which also uses OFDM. You might just as well say this is a review of an LTE network, or that a review of Sprint's 3G network (CDMA) is a review of T-Mobile's (UMTS/W-CDMA).

Re:So a nearly-wimax review of something else?

[Ctrl-Z]

What in the world does that mean? Why is it not WiMax? WiMax can be implemented using OFDM. Which WiMax standard was not final? 802.16e?

I think this whole thing needs [citation needed]

.

Re:So a nearly-wimax review of something else?

[lysergic.acid]

well, the success of this test shows that orthogonal frequency-division multiplexing can be used to implement wireless last-mile broadband.

the fact that this is a less-mature technology (was deployed before the WiMAX standard was finalized, so it is likely using an old draft of the WiMAX standard) means that we might be able to expect better performance from the official WiMAX protocol.

if anything, this test shows how WiMAX will perform under real-life conditions involving steel buildings, electronic noise, and moving network nodes. so far the results are positive.

if the current WiMAX standard has solved the problem with non-stationary network nodes, then it would surpass 3G cellular data networks in all ways, especially pricing.

Re:So a nearly-wimax review of something else?

[santiagoanders]

Likely it means they do not use the same MAC layer messaging and control, but the PHY layers have much in common. Perhaps they even use the same subcarrier arrangement?
Difference may be: different bandwidth (WiMax can use up to 20MHz bands), different coding schemes (WiMax can go up to 64QAM + several different ECC methods), lack of MIMO (WiMax can have a 4x4 antenna arrangement, but I doubt that this will become a reality anytime soon).

Re:So a nearly-wimax review of something else?

[negRo_slim]

Sounds like your splitting hairs to me...

Clearwire currently uses Expedience wireless technology, dubbed Pre-WiMax, transmitted from cell sites over licensed spectrum of 2.5-2.6 GHz in the U.S. and 3.5 GHz in Europe.

On May 7, 2008, Clearwire and Sprint Nextel's wireless broadband unit Xohm announced their intent to merge, combining Sprint's 4G WiMax network (Xohm) with Clearwire's existing pre-Wimax broadband network.

Perhaps the cheaper slower access plans will use the older tech? Either way, they seem similar enough to warrant talking about them both in this instance. But as someone who in the past used Clearwire for 1+ years. I will say it was generally acceptable. Latency was an issue and Bittorrent wasn't usuable, though I've heard otherwise from a few people. However, in the end it was the latency that made me move on... I just couldn't justify paying what they wanted when half the time I was over 3secs away from my needed servers. In the end I posted a days worth of latencys with timestamps to the tubes and received an email, out of nowhere, from someone with Clearwire corporate. But really there was nothing they could do, it was a physical limitation of the service as far as I can infer. As it only occured in certain areas of town, most notably the areas I ate, slept, showered and generally lived. Too bad it wasn't as portable as the commercials would of lead one to believe, but something about a modem the size of a hardcover A Brief History Of Time with a wall wart doesn't scream mobility to me.

Re:So a nearly-wimax review of something else?

[Guspaz]

That sounds a lot like what Bell Canada did; they launched a pre-spec WiMax service years ago.

Saying that "WiMax Is Finally Coming" is a bit late, though; Wikipedia lists hundreds of existing deployments:

http://en.wikipedia.org/wiki/List_of_deployed_WiMAX_networks

Re:So a nearly-wimax review of something else?

[jaakennuste]

Not before 2011. Im talking about mobile wimax. And still, customers are owned by mobile telco operators. Jack http://seoapplied.blogspot.com/

Re:So a nearly-wimax review of something else?

[Ungrounded Lightning]

So, this is a review of WIMAX, except it's not of WIMAX it's of something else? Can we review Wifi next to see how T-Mobile's 3G service is in my area too?

Much of the WiMax standard settled early. The physical layer was part of that. But there was a long time while some details were being hammered out.

During this time a number of vendors came to market with equipment that conformed to as much of the standard as seemed stable and took a guess at how to fill in the rest or how the arguments would settle out. Perhaps they'd be able to meet the final standard with a firmware change, perhaps they'd need to change the hardware somewhat.

This interim equipment worked about the same way, and as well in terms of coverage, noise immunity, multipath immunity/use, speed, etc., as equipment conforming to the final standard would. The downside for a customer WISP was potential inability to interoperate with standardized, cheap, multi-supplier equipment without reflashing, or possibly replacing, the early-adopter hardware - leading to higher costs and potential loss of future customers (such as those with conforming-only chipsets built into their laptops). The upside was that they could deploy their networks RIGHT AWAY, getting investment when money was available, establishing a footprint and a customer base (who would be hard to lure away with service only about equivalent), getting revenue from the expensive bandwidth licenses, and so on.

So a number of companies, such as Clearwire, chose to take the risk in order to get a jump on the competition and become established in broadband-underserved areas.

So the nearly-WiMax in question will have essentially the same properties as true WiMax, with the primary exception of interoperability with commodity WiMax hardware, making the review a useful one.

And possibly one other thing: One of the issues with the early versions of the WiMax spec was its poor handling of doppler shift, making it unsuitable for use on cars, busses, and trains - at least when moving at freeway/railroad speed toward/away from the associated base station. (I'm not sure what happened to that. I think they did NOT fix it in the final standard. I was working with a couple colleagues on a potential WiMax startup and we threw in the towel when it became apparent that you couldn't get prototype silicon or specs from the vendors unless you were already a {VERY} large company with an established relationship.)

Re:So a nearly-wimax review of something else?

[anothy]

from memory (former WiMAX Forum member), all the revisions to the standard up through current put the target for motion at 70mph. fine for cities and lots of commuter rail, but you'll run into problems on high speed freeways or long distance trains. this was not viewed as a defect; nobody was working on changing it.

the thing that's relevant here, which i think is often missed, is the difference between WiMAX and 802.16. ISO, in 802.16, specifies most of the technical issues, especially at the lower levels, and the WiMAX Forum, in a series of documents, specifies lots of stuff above and beyond that. the two organizations have a very high impedance feedback loop, so the Forum tries hard to just use whatever ISO has already done. wifi and 802.11 have a similar relationship, but wifi layers much less on (because they have less ambitious goals).

Bandwidth limits?

[MBGMorden]

There are already cellular broadband cards available from most carriers that seem to perform at fairly similar speeds. My main concern is what type of (monthly) bandwidth they offer. Standard practice from MOST carriers seems to be a 5GB per month limit, which is just ridiculously low (you could literally kill your monthly bandwidth with a single HD video rental from iTunes or Xbox live). In looking the main carrier that I couldn't find had a limit stated was Cricket - but their service area doesn't quite reach out to my house.

So long as my DSL offers effectively unlimited bandwidth (I only have a 1Mbps DSL connection so it'd hard to pull down more than the connection support anyways), I'll stick with them, even with some reliability problems.

Re:Bandwidth limits?

[ajdowntown]

See my other post, but according to my friend that works for the WiMax project, there will not be any bandwidth cap. The reason the cellular data cards needed bandwidth caps is because the problem with the towers. Each tower for 3G technologies have about a T1 running to them, so the line can easily get saturated. From what I understand, the WiMax towers have something crazy like a 10GB line running to them, thus not having to have the same caps as the cellular networks to artificially keep usage low. He also said that the WiMax team will re-evaluate the unlimited usage after a year or so to see if it is still feasible.

Re:Bandwidth limits?

[entrigant]

I think you might be missing the point for a cellular modem. It's not meant to be your primary internet gateway for all of your multimedia needs. I have an EVDO modem built into my laptop and a 5GB subscription. The point is when I'm on the road or out of the office working with a client I can send/check e-mail, use jabber, ssh, and load web pages. None of these activities come close to taxing my 5GB limit.

Re:Bandwidth limits?

[MBGMorden]

Yes, but for many people, particularly in rural areas, cellular is the only way to get a decent connection speed (without resorting to satellite was has reliability problems and similar bandwidth caps - though you do get to at least revert to dial up speeds after exceeding those).

In that case it's not really a question of what it's "meant for". It's a question of what it can do. For rural people with no other options, cellular is a valid solution if they could get the bandwidth cap to something more reasonable.

Re:Bandwidth limits?

[morcego]

I know at least 2 people who use celular network exclusively for internet access. The reason is celular is the only kind of "broadband" (ie: not dialup) available at their location.

Re:Bandwidth limits?

[afidel]

At what it costs for a cellular modem you SHOULD be able to use it as a primary internet connection, just like no-one expects to need a landline once they have reliable, reasonably priced cellular voice service you shouldn't need a $50/month landline internet connection AND a $50-100/month cellular internet connection.

Re:Bandwidth limits?

[limaxray]

Those type of people are in the vast minority - most cellular broadband customers use it for mobile business purposes where 5G is more than enough. In most carrier's contracts it actually says you can NOT use it as a primary (or even as a backup) site internet connection. They are intended solely for mobile connectivity purposes.

Re:Bandwidth limits?

[electrictroy]

WiiMax? Is that a Nintendo console with 720p or 1080i output? I bet there will be a long waiting line; and probably scalpers on Ebay charging $1000 to get one.. I'll wait and pick mine up after Christmas.

Re:Bandwidth limits?

[MBGMorden]

They're certainly selling it as such. My brother uses one of these and the local office touted it as the perfect solution for them since they're out of range of DSL or cable modem. He also referred to the 5GB monthly cap as "virtually unlimited" (so there are some reputation qualms I have there), but that office certainly was marketing it as a primary connectivity option. I'm sure they're not alone.

And even in the absence of such marketing by a local office, I see nothing in any of the national marketing materials that points to it NOT being intended as a primary connection, or that points to it being solely intended for the mobile market.

Re:Bandwidth limits?

[electrictroy]

>>>for the WiMax project, there will not be any bandwidth cap.

Riiiiight. And Comcast actually gives me the 10 megabits/second I paid for. Yep. Uh huh. Sure. Last I checked my Utorrent is maxing-out at just 100 kilobytes/s, aka ~1 Mbps, not 10.

Re:Bandwidth limits?

[electrictroy]

If rural residents have phone lines running into their house, they should be able to get some kind of DSL which would be ~10 times faster than dialup (300-500 kbit/s) or maybe 20 times faster (600-1000 kb/s). ----- Plus DSL would be a lot cheaper than either cellular or satellite (~$15 versus $60 a month). The Verizons of the world just need to stop dragging their feet & install the necessary equipment to make DSL work. The phoneline wiring into everybody's home is already present and waiting to be used.

Also:

In defense of dialup, it's not that bad if you're just surfing the web. While traveling, I use Netscape ISP which uses image compression to give my phone-internet an effective speed equal to DSL at home.

Re:Bandwidth limits?

[Cajun Hell]

In that case it's not really a question of what it's "meant for". It's a question of what it can do.

And what can be done under a 5G/mo cap is a shitload: basically, everything you were doing on the internet 10 years ago. Of course you want more, but it's pretty awesome as-is.

Re:Bandwidth limits?

[Tony Hoyle]

My 3G modem costs £5 ($10) a month for a 1gb cap, which is fine for out and about.. If I want more I plug it into the home connection.

For $50 a month I'd expect unlimited, personally.

Re:Bandwidth limits?

[afidel]

Cool, glad to hear things don't suck in the UK, in the US you generally only have one plan tier available for tethering or cellular modem capabilities and it's generally priced between $50 and $75 and is "unlimited" (no time limit but ~5GB of transfer with severe restrictions on what types of services and equipment you can use it with).

Re:Bandwidth limits?

[MBGMorden]

Not sure where you're getting your info, but TONS of customers have access to phone lines but not DSL. DSL is good for at most a few miles from the switching station. Phone lines can extend out dozens of miles from those stations (if not farther). Not to mention your $15 price estimate is WAY off base. The starting package here (for people who even have access to it) is $50/month for 1Mbps (and then $60/month for 3Mbps and $70/month for 5Mbps). While the speeds are generally higher for most DSL providers, I haven't seen the price drop significantly - you might find a few with starting prices around $30 if you shop around but $15/month is unheard of in my searches.

As to dial-up, maybe you're just less picky than me, but having used dial-up just to check discussion forums and such when diagnosing problems at other people's houses, I can say that dial-up is damn near unworkably slow even compared to a 1Mbps DSL connection, even for strictly web access. It worked OK when email was plain text and cached to your local drive, and when web pages were an order of magnitude less complex, but on today's internet dial-up just isn't an option for anything but the most patient of users.

Re:Bandwidth limits?

[MBGMorden]

I'll not argue that a lot can be done on 5GB's - and if it was between that and going back to dial up I'd suffer with the 5GB limit (I know several people doing that - I have crappy DSL so I'm not down to that yet), but there's no denying that for MODERN usage, 5GB is pretty low. Low enough for me that I'd probably do my general browsing with image downloading turned off and saving my bandwidth for more important pages and file downloads. I mean the next WoW patch alone is taking nearly a gigabyte (and when you work in the inefficiencies of Bittorrent it's likely over that) by itself. Factor in a few podcasts I listen to (some video) and a moderate amount of general content downloading from iTunes and the like, and that 5GB limit runs out QUICK.

Effectively, 5GB would be enough for me, as you said, 10 years ago, but not now.

Re:Bandwidth limits?

[MBGMorden]

You know, $10/GB wouldn't even be as bad if they would scale it up linearly.

The cell providers here normally charge $60/month for 5GB, but if you go over that, it's $0.25 per MB (yep, megabyte).

So your first 5/GB is $60 and your second would be $1280. That's just ridiculous.

BTW, for Verizon at least, the only step DOWN from that $60 plan is a $40 plan where you get 50MB per month (again, that really is fifty megabytes - only stressing as if I hadn't checked on this myself I'd read that and assume that someone left out an extra zero or something) with the same overage charges. Prices on this stuff is just insane.

Re:Bandwidth limits?

[fiddler.wo.a.roof]

DSL does not work if there is fiber between you and the access point

Re:Bandwidth limits?

[elrous0]

Yes but WiMax, unlike current cell modem service, is apparently hoping to compete with DSL and cable. If they're going to do that, they need to be prepared to offer similar usage caps to existing DSL/cable providers (a lot more than 5 GB per month).

Re:Bandwidth limits?

[gravis777]

I can vouch for the T1 to the 3G towers. A friend of mine spent a year setting these up. Now, this may be fine if you are out in someplace like Venus, Texas on an iPhone, as there will only be a few people on this tower at any given time. However, what about in someplace like Downtown Dallas? There are times when I cannot place a call because the network is jamed (although that is seeming to happen less and less, it seems like my carrier has recently upgraded their capacity).

The train between Fort Worth and Dallas has one of the first metro WiFi deployments in the country (whether more have come up since, I do not know). They use some type of cellular modem to provide this access. There are obviously areas and times of day where the speed is much faster than at others (and this is not due just to the fact that you have 30 people on one cellular connection either, there are times of day and areas where I am the only person on the train, and still have these issues).

Point is, I am kinda wonder, living about as far outside of the city as I am (and can still be considered to be in a suburb), how long it will take me to get fiber to the home if these providers cannot even run them to their towers.

Re:Bandwidth limits?

[Lueseiseki]

Did you seriously expect that you could constantly download 1.25 megabytes per second of data? I don't think you understand how the internet, (much less torrents) work.

Re:Bandwidth limits?

[mattack2]

I have no access to DSL and I'm in Silicon Valley!

Re:Bandwidth limits?

[mattack2]

att.com shows $14.99 "basic" DSL with a 2 year price guarantee. They were advertising that price for a while, then went up to $19.99 for a while.. now I guess they're back down again.

(Hmm, I still can't get their 'DSL', but I apparently finally can get some of their "High Speed Internet" options. Is it different from DSL? I'm not sure.. they sure seem to list them differently.)

Re:Bandwidth limits?

[Gavagai80]

AT&T partners with a satellite provider (wildblue) to offer a branded "high speed internet" option to people who they don't actually service.

Re:Bandwidth limits?

[Trogre]

Literally? Was my monthly bandwidth even alive in the first place?

hardware

[Anonymous Coward]

Is there any light weight device available that converts wimax to wifi (ie. battery powered that everyone can carry around)? Seeing as there are so many devices (including cell phones) available that support wifi it would be a shame to not use em 'as god intended' ;)

Re:hardware

[I.M.O.G.]

Yes, a wireless router would do the trick - The DWL-G730AP would be like what your looking for. It can be powered by USB also so it fits all your stated reqs. The unit would plug into your wimax modem, which would not be battery powered as you had hoped - but most places have electric outlets.

Thats as close as you are going to get to a continuously mobile wifi connection that travels with you from currently available products.

Cheese State Ahead of the Curve

[feld]

Madison, WI has had WiMAX for over a year, but it wasn't been publicly launched until January. TDS Telecom offers WiMAX not just for internet, but for phone! You get indoor or outdoor WiMAX equipment depending on how the survey of your location goes, and you also get a UPS for the equipment so it doesn't go down when the power's out.

Residents using it report that it gives better call quality (which is probably due to poor phone lines) and say their connection is faster than landline DSL (also probably line quality, but could be less congested networks).

Here's some infos on what we have:

http://www.tdstelecom.com/absolutenews/templates/news_template.asp?articleid=496&zoneid=5

Re:Cheese State Ahead of the Curve

[lysergic.acid]

hrmm... so is the phone service basically just VoIP over WiMAX? if so, then i see a lot of other cities following in Madison's footsteps.

it makes perfect sense to merge specialized communications networks, such as telecommunication, with internet access. nowadays an internet connection is just as important as a phone line, and you can transfer digital audio/video/text and any other data over the internet. so a dedicated telecommunications line is just redundant.

and when municipal Wi-Fi/WiMAX becomes as standard as roads/power lines, then we'll start seeing Wi-Fi/WiMAX mobile phones. we'll probably first see hybrid carrier-neutral wireless handsets, which can use Wi-Fi connections when available, but will default to cellular carriers if an open Wi-Fi network can't be found. and as slow adopters finally catch up to cities like SF, Madison, etc. and Wi-Fi coverage becomes ubiquitous, then more people will start using pure wireless VoIP handsets.

I've had it in SE Idaho

[jb_02_98]

I've had Wimax here in southeast Idaho for a while. It seems to work ok, the only problem being that they got overwhelmed when they started the service and had some bandwidth shortages due to uptake being quicker than they had originally planned. Other than that, it seems pretty reliable and seems to work well. I'm excited to see the tech rolled out elsewhere.

From TFS

[FredFredrickson]

The good news is that this time, the carrier promises look to be delivered on.

Is there something I missed? I don't understand...

WiMax is indeed coming

[ajdowntown]

I have a good friend that works directly for the WiMax team. According to him, there are many cities all ready to go with WiMax, and the first city to sell it will be Baltimore, with two months later Washington DC and LA I believe coming on next. Then, if all turns out well, 30 cities in 2009, and by 2010, most all major metro areas being covered. My friend already has a working WiMax card at his house (here in DC) and has been using it for the past 2 months. He said Baltimore was going to be first because it is the city with the most "complete" coverage. There is even suppose to be some sort of ceremony going on with the mayor of Baltimore attending. I am also told that anyone from the DC area could potentially drive to DC to buy the WiMax cards and use it back home in DC no problem.

My friend also said that the current limitations are with the WiMax cards, only getting about 2 megs a sec, while the ones coming next year will be almost twice as fast.

This is a good friend, so I trust what he says, but, as always, YMMV.

Re:WiMax is indeed coming

[Anonymous Coward]

Hi AJ: small correction: WiMAX is here now! I am the friend you refer to :) Posting anon due to various disclosure agreements, etc. We launched Monday in Baltimore, and the service is commercially available now ( http://www.xohm.com/ ). Performance is also MUCH better than the "review" See the following "review of the review" at ZDNET: http://blogs.zdnet.com/computers/?p=228 [zdnet.com] In short, what was "reviewed" is NOT WiMAX, and does not reflect true "real world" performance. WiMAX works wonderfully with mobile handoffs, and has better performance than the Clearwire network that was tested. Clearwire's current networks are not yet WiMAX compliant. XOHM's are.

MOBILE WiMAX

[santiagoanders]

WiMAX has been around for a while - the IEEE 802.16-2004 standard has been around a while, mostly for stationary links in rural or semi-wilderness areas. I know that AT&T has deployed some stationary WiMAX services in Alaska.

The XOHM network that Sprint is unrolling is a MOBILE WiMAX network. This is IEEE 802.16e-2005. It adds additional features meant to help with mobility (e.g. Hybrid ARQ). Some of these features may or may not be present in the Clearwire service.

There are a lot of vendors that are implementing WiMAX hardware, so one review isn't going to say everything.

So the most important question

[The Cisco Kid]

Is WiMax intended to upgrade/replace Wifi (eg, I buy my own WiMax router, connect it to my own Ethernet network, and can then access said network wirelessly at extended range and/or speed with off-the-shelf hardware?) or is it intended to replace GPRS/3G/etc cell data networks (Eg, I bend over and get fscked with a long overpriced contract to a cellco, have to buy their proprietary hardware to use with it [which isnt of using standards like ethernet, plugs in with pcmcia only, and requires windoze-only proprietary software drivers], and then get the "privilege" of being billed per-kbyte of data I transfer over it)

If the former, than Yay WiMax. If the latter, then *yawn*.

Re:So the most important question

[santiagoanders]

Mobile WiMax does not replace Wifi - it's the latter. But I doubt all of those negative statements are true.

Re:So the most important question

[compro01]

1. No. Wimax has nothing to do with wifi. Wimax is a last-mile type connection, much like DSL, cable, etc, with the capability to act like cellular broadband in the sense it does not necessarily require a fixed antenna and thus can be mobile.

2. Maybe. I've heard thoughts of cellular service along the lines of VOIP-over-wimax, though I imagine this is several years away, if it even pans out.

3. Provided it uses actual wimax and not a similar non-standard, it would act like a modem and connect via ethernet/wifi in a fixed mode and usb/pcmcia/expresscard/built-in/etc. when used in a mobile mode.

WiMax and OFDM

[loose electron]

Just to clarify - OFDM is the modulation method used to convery data. Modulation methodology doesnt really tell you much about bandwidth and data rate, since a communication channel design can trade these properties off in an interactive manner when the design standard is defined.

The good news is that WiMax is designed to do data over long distance (measured in Km's) rather than the the duct tape installations of WiFi, which was never supposed to be used for distance data communication. Some of the crazy WiFi installations that are out there are 5 star silly, trying to do things that WiFi systems were never designed to do.

Some useful links:
http://en.wikipedia.org/wiki/Wimax
http://www.wimaxforum.org/
http://www.wimax.com/
http://www.networkworld.com/topics/wimax.html

If you want to get into the nitty gritty of the details, the IEEE has the 802.16 standards for all the details as well.
The good news is that this time around it actualy seems to be happening. It's out there in a big way (read some of the deployments in the above links) but not widespread yet.

Re:WiMax and OFDM

[nmos]

Just to clarify - OFDM is the modulation method used to convery data.

Is "OFDM" a real thing or is it just some dyslexic's way of spelling ODFM?

Re:WiMax and OFDM

[TechyImmigrant]

Just to clarify - OFDM is the modulation method used to convery data.

Is "OFDM" a real thing or is it just some dyslexic's way of spelling ODFM?

Orthogonal Frequency Division Multiplex. But you already knew that.

OFDM variants of 802.16 have been around for a while. OFDM is a generic term for a form of modulation. However in 802.16, OFDM is a specific physical layer specification that covers more than modulation. It covers the frame structure and things that in other specs would be considered a MAC.

There are other PHYs in 802.16. SC, SCa, OFDMA etc.

The one that is the basis of the promised mobile WiMAX networks is OFDMA. The point being it has super sexy multiple access in the uplink where the multiple users transmit at the same time, on the same frequency with the orthogonal subcarriers from the same OFDM symbol magically interleaving.

OFDM mode is more to do with fixed deployments.

They both make 3G look like RS232.

Also the link security is actually secure, which is my fault. Sorry. The backhaul isn't though. It never will be. Use end to end security because VoIP has LI.

Re:WiMax and OFDM

[Agripa]

The one that is the basis of the promised mobile WiMAX networks is OFDMA. The point being it has super sexy multiple access in the uplink where the multiple users transmit at the same time, on the same frequency with the orthogonal subcarriers from the same OFDM symbol magically interleaving.

I have been investigating digital radio design and have a couple questions about this. My specific interest is in digital radio design for use in hostile RF environments.

Are the radios full duplex allowing continuous carrier frequency feedback and adjustment? I guess even if they were half duplex then doppler shift adjustment would be possible. I have wondered however if this is related to any problems with high speed mobile usage.

Do the receivers suffer from in band dynamic range limitations or does having a continuously adjustable transmitter output power prevent that type of problem?

Re:WiMax and OFDM

[TechyImmigrant]

The standard supports both half and full duplex radios. The BS scheduler takes into account the capability of the SS when scheduling when it can receive or transmit.

The advanced pilot structures in OFDMA permit rapid doppler compensation, MIMO and other funky stuff.

The period ranging is increased in rate for mobile terminals to provide for estimation of the more rapidly changing channel and appropriate power and timing adjustment.

Every radio, especially a super linear one needed for OFDM will have dynamic range issues, but they are not particularly insurmountable. There are the usual collection of PAPR reduction and power control mechanisms in place in the spec.

WiMax

[salarelv]

Eem...we have had WiMax connection for more than 2 years in Estonia. Main cities are covered and prices start from $30 for 256Kbps and up to 768Kbps. Some people have complained that WiMax isn't so good in the wild (large trees reflect the waves). More popular is a CDMA service from the main energy grid provider.

Re:WiMax

[santiagoanders]

Yes, many countries are way ahead of the US on this, especially Korea.

See WiBro:
http://en.wikipedia.org/wiki/WiBro

Re:WiMax

[raju1kabir]

Also had it in Malaysia for a little while. About US$30/month for 1.2 megabit, $65 for 2.4 megabit. From what I've seen, it delivers as promised, but the uptake hasn't been high enough yet to really see how it performs under heavy use. When they do their demos they sometimes use an uncapped account and seem to get about 5mbps.

Live WiMax test in Baltimore!

[branchingfactor]

Laptopmag.com is live blogging a test of the XOHM WiMax deployment in Baltmore http://blog.laptopmag.com/live-with-xohm-wimax-in-baltimore

Re:Live WiMax test in Baltimore!

[rnelsonee]

Ah, thank you - I heard conflicting reports on whether or not XOHM would be available at all in October.

For those that want to check coverage, go here:
http://www.xohm.com/baltimore/

It looks like almost full coverage for downtown, Fells Point/East Baltimore, Charles Villige, etc. Considering Comcast mistakenly physically disconnected my internet on Thursday and I still have no internet, I'm in the mood to switch!

Clearwire - Security through Obscurity

[IsThisNickTaken]

Out of curiosity I called Clearwire after seeing one of the inserts. I was curious about the security they offered. I eventually spoke to a tech support person who verified something along the lines of "We use OFDM to protect your data. The information is not encrypted. I can't tell you our proprietary security details." I had mentioned that as a potential client who is interested in security, I would not accept the fact that OFDM is shiny and new and no bad guys can demodulate it as a good answer.

Re:Clearwire - Security through Obscurity

[MukiMuki]

Isn't this what firewall software and SSL/SSH is for?

Re:Clearwire - Security through Obscurity

[IsThisNickTaken]

I agree that anything requiring real security should be done over SSL/SSH to provide end to end encryption. If I am using a wired connection and not using SSL/SSH, anyone between my host and the other endpoint can tap in and see my traffic. This would typically be people at my ISP, their peering ISPs, backbone providers, etc. With unencrypted wireless, in addition to people providing the infrastructure, anyone with the right type of radio receiver can see the traffic that is not sent over SSL/SSH.

I'm not sure how firewall software addresses the "I don't want anybody with the right radio and proximity to me or the wireless tower I am communicating with to see my packets".

Re:Clearwire - Security through Obscurity

[TechyImmigrant]

FYI - The WiMAX Standard Profiles require that all devices support strong payload encryption over-the-air, as spelled out in the 802.16 standard.

Whether a network is configured to enable that feature is an operator choice; this generation of equipment may still have 'compromises', as in "It's supported!", but if you turn it on for everybody the scheduling of users gets crappy and packets dropped because the network processor's memory bandwidth is eaten up by 2x more users data going to and from the HW crypto accelerator.

Yes, I've worked in wireless telco.

The crypto overhead is 12 bytes per MPDU. Given the packing and fragmentation, this doesn't mean 12 bytes per MSDU aka IP packet.

Carriers want it on not because it protects users, but because it protects them from theft of service.

The per packet processing overhead is effectively zero if you implement it right. The spec was written the way it was written to permit an inline AES-CCM unit in the datapath with a latency of no more than 11 clocks. A tiny sliver of silicon can cope with all the crypto load of a BS. Implementers who decide to offload the crypto onto processors are fools.

Re:Clearwire - Security through Obscurity

[TechyImmigrant]

As before, crypto in 802.16 is link security. Good for hiding your on air packets but that is a side effect of the primary purpose of preventing theft of service.

It has nothing to do with end to end security. Use SSL/SSH/TLS/IPSec or whatever for that.

And the prize for most stilted sentence ever...

[Qubit]

"The good news is that this time, the carrier promises look to be delivered on."

Really? What exactly is being delivered, and to whom is it being delivered?

If the carrier promises look, then can I get some, and does it come in Kilograms?

I think that what they're trying to say is:

The good news is that this time, the carrier's promises look to be delivered on."

Of course, that's still horribly confusing. Let's move that around:

The good news is that this time, it looks like the carrier will deliver on their promises."

Much better.

Re:And the prize for most stilted sentence ever...

[g0at]

While your sentence is vastly better, I would further fix it to read "it looks like the carrier will deliver on its promises."

-b

Line noise

[tepples]

If rural residents have phone lines running into their house, they should be able to get some kind of DSL which would be ~10 times faster than dialup (300-500 kbit/s) or maybe 20 times faster (600-1000 kb/s).

You can't get DSL if the connection from the closest access multiplexer has an unacceptable amount of line noise above the audio band. Runs of longer than two miles tend to do this.

Re:Line noise

[bill_mcgonigle]

You can't get DSL if the connection from the closest access multiplexer has an unacceptable amount of line noise above the audio band. Runs of longer than two miles tend to do this.

You're right, though I suspect that's what electrictoy meant by 'proper equipment'.

Our local line has a junction box that went open for six months before Verizon stopped by one day last year and threw a black trash bag over it.

High latency

[wormeyman]

I have Clearwire up here in Washington state and while i connect at 1.1mbs on my up to 1.5 mbs connection i have horrible latency due to it being a wireless connection i ping 130ms to google and get auto kicked from online servers for having too high of a ping. I would definitely agree with the final sentence in the article "If your main use is for video downloads and 3D gaming, that's another story. "

Re:High latency

[Sean0michael]

Mod parent up. It isn't something that gets mentioned usually, but it is important.

I also have Clearwire in Seattle. When playing WOW, my latency can be all over the map, depending on who's using the connection. This summer, I was usually lagging 210-550 milliseconds, which for a newb was tolerable. Sometimes though it would spike to 2000-3000 milliseconds, which made playing the game quite a pain. It was highly dependent on the time of day -- early morning was always the best for gaming, dinner hour the worst.

For anything other than that, I'm pretty satisfied. They block Skype to sell their own VOIP stuff, but I use my cellphone exclusively anyway so it doesn't affect me. My internet browsing is fine, and downloading Linux ISOs and such is no more of a pain than doing it with Comcast. Plus, if I move out of the apartment, I can take my Internet with me and be hooked up the same day I move in -- no waiting on some cable guy to come around.

And latency...?

[Nexus7]

Another review that pretends that latency is irrelevant.

A Solution in Search of a Question

[WillAffleckUW]

The problem is that WiMax is really just a method to get higher revenues from an unsuspecting mobile wireless public - a solution, in other words, in search of a question for which it can be the answer.

But this leads us to the end result that we don't Need WiMax, we don't Want WiMax, and we sure as heck don't want to pay $100 a month for something when the slightly slower but much more available alternative is mostly free.

It's like a Hedge Fund. The markets got along fine without them, and they cause more trouble and suck money out of consumers far more than they deliver value.

Just. Say. NO.

Re:A Solution in Search of a Question

[WillAffleckUW]

(note - when I say $100 a month I'm tallying up True Cost - basic fee, standard add ons, local sales tax, county sales tax, state sales tax, fed sales tax, fed fees - your mileage may vary but it will probably be in the $90 to $120 a month range when you add it all up)

Re:A Solution in Search of a Question

[Carlosos]

Clearwire starts at $25 (they try to get you with a much lower promotional price) and I don't believe that they will add $75 in taxes. It's $5 more if you don't own a modem. (or purchase for $100)

Re:A Solution in Search of a Question

[WillAffleckUW]

Strange, a number of people posting on here have directly quoted prices that work out to what I said.

You must mean the initial teaser price.

Re:A Solution in Search of a Question

[Carlosos]

It only gets that expensive if you also have VoIP phone service with them or also more expensive for the higher speeds but the people that I know that get it go with the slowest speed or the twice the speed for $5 more. For the people that just want cheap internet it is pretty good but for everyone else that wants to pay 10-30 more for more speed are better off with DSL or cable.

Here are the prices of clearwire:

ClearPremium
Up to 1.5Mbps download
5 email accounts
2 yr term
Regular Price: $ 34.99 /mo
NOW $ 9.99 /mo
for the first 4 months
$ 100.00 in savings
+ Free Activation
+ Free Shipping

ClearPremium Plus
Up to 2.0Mbps download
5 email accounts
2 yr term
Regular Price: $ 44.99 /mo
NOW $ 24.99 /mo
for the first 3 months
$ 60.00 in savings
+ Free Activation
+ Free Shipping

ClearValue
Up to 768Kbps download
3 email accounts
2 yr term
Regular Price: $ 24.99 /mo
NOW $ 19.99 /mo
for the first 3 months
$ 15.00 in savings
+ Free Activation
+ Free Shipping

ClearPremium Choice
Up to 1.5Mbps download
5 email accounts
2 yr term
Regular Price: $ 29.99 /mo
NOW $ 29.99 /mo
+ Free Activation
+ Free Shipping

Re:A Solution in Search of a Question

[WillAffleckUW]

note the phrase ... "for the first x months"

I said the ACTUAL PRICE.

Re:A Solution in Search of a Question

[Carlosos]

The list has both prices!
Regular Price and NOW are two different prices. The "NOW" prices is the promotional price. The regular price is the actual price.

Re:A Solution in Search of a Question

[WillAffleckUW]

thank you for agreeing with my truthful statement.

What about the latency?

[BillTheKatt]

I'd be interested to know what the latency was like. Bandwidth is just one component of performance. Poor latency and/or jitter means it wouldn't be very useful for VoIP or games.

Clearwire in Daytona

[Carlosos]

Here in the Daytona Beach Area, we got Clearwire as WiMax provider since about 2 years and a lot of people like it because it is cheaper than DSL and cable. Clearwire also advertised itself to work on the beach. Who doesn't want to sit on the beach and have Internet access? (even though I know nobody that has ever used it like that)

WiMax deployment in Pakistan

[aakhan]

Pakistan apparently has one of the largest WiMax deployment in the world. I have been a user of WiMax for over five months now, and been nothing but happy with it.