AT&T 3G MicroCell: A Comprehensive Exploration
by Brian Klug on April 1, 2010 1:55 AM EST- Posted in
- Smartphones
- AT&T
- Microcell Review
- Mobile
I mentioned earlier that voice and data both work fine, as long as you're inside the MicroCell's coverage radius. So what happens if you step outside? In theory and per advertising, your call is supposed to transition "seamlessly" to the nearest macrosite. In fact, the first time I tried walking out of location 1, it transitioned perfectly! I then proceeded to spend over a half hour trying to repeat my initial success...
The Theory of Handovers
But before I dive into the problems I experienced, let's briefly touch on some of the tech behind it. There are two types of handover that happen on a cellular network: soft and hard handovers. In a soft handover, the phone is continually talking to multiple macrocells at the same time - the transition happens seamlessly because you're already connected and communicating with towers you're going to handover to. This is a make-before-break transition. The transition is simply a matter of choosing which one has the best link quality, and this is generally how most transitions happen because it's robust.
The other case is a hard handover - this is less seamless break-before-make transition that's nearly instantaneous in practice, but still perceptible if you know what to look for. In a hard handover, the phone literally releases its active connection and transitions to another. Also of relevance are so-called vertical handoffs - these are transitions that happen across network technologies, in this case from UMTS to GSM, though other cross-technology handovers are possible as well. There's a huge amount of complexity to these systems; effectively handing off users while maintaining voice and data sessions is a challenging multidimensional problem. One that's often taken entirely for granted because of just how well we're used to it working.
So you can imagine my surprise when I discovered that the handover from femtocell back to public 3G wasn't just rough, it's downright crude. First of all, virtually every femtocell handover is of the hard variety, and in practice almost all of the ones I saw were also vertical, from UMTS (3G) to GSM (2G). During that long provisioning process, I mentioned that the femtocell is building a rough list of all the macrocells it can see. Hopefully, it can see a few of both 3G and 2G variety, which it passes onto the phone in the form of a neighbor list. The phone also builds out its own neighbor list, which you can see some of in the Field Trial (*3001#12345#*) dialer application. It's been gimped significantly since the iPhone 2G, but there's still enough here to get the point across:
Neighbor Cells - Just like advertised
Anyhow, when you leave the femtocell's radius, if there's a macrocell in range and your phone can hard handover to it, the call continues. Hopefully this is what happens, otherwise the call drops. Of course, the big caveat here is that if you're installing the femtocell in a place with little to no signal (why it's there in the first place) handover is going to be a difficult prospect. That's why I tried the AT&T MicroCell both in an area with good existing coverage, and one with poor coverage. The results at both were equally disappointing.
AT&T advertises an effective range of 5000 square feet. This seems about right, but it's signal dependent. Location one is just over of 2000 square feet, and continual femtocell coverage barely makes it across two rooms. Location two is effectively 5000 square feet, and femtocell coverage includes the whole house, guest house, and most of both long driveways. Again, this is largely in part because the femtocell is sitting atop existing 3G spectrum - there's no spectrum overlay just for microcells yet. The result is that if signal is bad where you are, your microcell range is larger. Conversely, if signal is already reasonable, you're not going to see more than a room or two of microcell coverage. It's a complex problem akin to the cell breathing phenomenon, and I think AT&T's 3G MicroCell product is doing a lot of ranging at setup.
Facebook
Twitter
RSS
63 Comments
View All Comments
Some1ne - Thursday, April 1, 2010 - link
So let me get this straight. I'm supposed to pay AT&T for access to a device that uses my own Internet connection to patch up holes in their network? That's just ridiculous. It's AT&T's inadequate network coverage that makes these devices necessary in the first place, and now they're actually trying to profit off of having poor network coverage. Pretty much removes any incentive for them to improve their network, now doesn't it?These devices should be provided free of charge, as a "sorry you can't actually use the network that you paid to access" kind of token. Anyone who pays for one of these is just giving AT&T one more reason not to fix their coverage issues.
Alexstarfire - Thursday, April 1, 2010 - link
I rather agree. Makes you wonder what they actually do with all the money they receive monthly. Also means that if you purchase one, much like how it should be if you use an unlocked phone, that your monthly bill should drop in price. Except in this case if they are using your broadband connection then it should practically be free since it provides next to no burden on them, though I don't know what happens after it goes through the connection.therealnickdanger - Thursday, April 1, 2010 - link
How do you know that the actual cost of the device and the technology driving it isn't already subsidized by your bill? Perhaps you're only paying 10% of what it really costs.vol7ron - Thursday, April 1, 2010 - link
Even if a subsidy were included, which would only cover some (not all) of the costs, the fact that people have to pay anything more for it is ridiculous given the nature of what a cell company is: a service. Cell phone companies are in business for one reason and by making you pay anything more to receive the core product is truely sad.There are other companies, like Cisco, that have built their own repeaters and Mobile-to-VOIP products, which I commend, because they are a technology company not providing the service. They're taking something bad, that they don't have control of, and making it bearable. Cell phone providers are at the other end, they have full control but are making you pay more, even though you aren't getting the initial benefit of what you're paying for in the first place.
zinfamous - Thursday, April 1, 2010 - link
This is kind of where I sit with the argument. a one-time ~$150 cost to the customer *may* be cheaper in the end, than having a network-wide upgrade that increases costs across all customers, paying more and more per month.Perhaps it also improves access to those willing, and needing increased network performance, paying a bit more for the premium, while those customers with little need for the bandwidth go on about their normal use, paying what they always have. It's like...a single-payer network structure! :D
DoeBoy - Thursday, April 1, 2010 - link
IT seems to me some people forget that companies are in business to make money. This is a great way for ATT to make a lot of extra money. I live in a rural area and i complain all the time in an area they say has coverage that does not at all. While this would aid me in getting better service it also would require me to pay for an inet connection which is not covered by att. Clearly they aren't a moral company when your service is so bad you have to have a product that uses some other technology(a la internet) and then charge the person not only for that product that gets you service but not even lower your bill since you technically arent using their towers really at all under this sucker. Clearly Verizon and ATT are both big 500lb gorillas. In europe its much easier to get a cheap cell phone deal and coverage. Clark Howard seems to think ATT and Verizon are going to end up being more corporate and smaller companies like t-mobile, cricket, metropcs and what not will fill in the void for the regular consumer.Some1ne - Thursday, April 1, 2010 - link
The problem is that when you look at the pricing matrix, not only is there a fixed upfront cost, there are also recurring monthly fees. It doesn't matter how much the up front cost is subsidized. The monthly fees mean that sooner or later, AT&T will be turning a profit on these devices.And even worse, the fees are higher if you're not already using AT&T as your ISP and/or land-line provider. That makes the least sense out of anything, since if you have a different ISP, then by running the femtocell you are completely unburdening AT&T's network, and dumping all the work onto someone else. The get to sell your bandwidth to someone else, and charge you more while doing it.
taltamir - Thursday, April 1, 2010 - link
in computers, the technology is made mostly of sand... it costs practically nothing.It is the technology you are paying for...
However there is one major component here, AT&T themselves look at it as a "cost cutting method"... in other words it is intended to cost them LESS, aka, they are making MORE of a profit on you if you get one of those then without.
The whole thing is absurd. You pay hundreds of dollars for a black box device with tamper protection and absolutely horrid performance (compared to wifi), then you pay a monthly fee for the privilege of using said device...
they should just put wifi in every device and have wifi be free (but they usually charge a monthly fee for that privilege as well)
ant1pathy - Friday, April 2, 2010 - link
You are, of course, welcome to change carriers. If you feel the service you are recieving is subpar and another carrier would be better for you, the termination fee is probably less than the cost of the box. If you're continuing to pay for a service that does not meet your needs and you can't really use, then you are the pefect consumer.Wolfpup - Wednesday, April 21, 2010 - link
I completely agree. It's absolutely nuts IMO.