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CDMA vs. GSM: What’s the Difference?

If you’re shopping for a mobile phone, you’re in for a lot of acronyms. Here’s what you need to know about two basic, yet important, terms.
CDMA vs. GSM: What's the Difference?

Two basic technologies in mobile phones, CDMA and GSM represent a gap you can’t cross. They’re the reason you can’t use many AT&T phones on Verizon’s network and vice versa. But what does CDMA vs. GSM really mean for you?

CDMA (Code Division Multiple Access) and GSM (Global System for Mobiles) are shorthand for the two major radio systems used in cell phones. Both acronyms tend to group together a bunch of technologies run by the same entities. In this story, I’ll try to explain who uses which technology and what the real differences are.

Which Carriers are CDMA? Which are GSM?
In the U.S., Sprint, Verizon and U.S. Cellular use CDMA. AT&T and T-Mobile use GSM.

Most of the rest of the world uses GSM. The global spread of GSM came about because in 1987, Europe mandated the technology by law, and because GSM comes from an industry consortium. What we call CDMA, by and large, is owned by chipmaker Qualcomm. This made it less expensive for third parties to build GSM equipment.

There are several variants and options carriers can choose, like toppings on their technological ice cream. In this story we’ll focus on U.S. networks.

What CDMA vs. GSM Means to You
For call quality, the technology you use is much less important than the way your carrier has built its network. There are good and bad CDMA and GSM networks, but there are key differences between the technologies. Here’s what you, as a consumer, need to know.

It’s much easier to swap phones on GSM networks, because GSM carriers put customer information on a removable SIM card. Take the card out, put it in a different phone, and the new phone now has your number. What’s more, to be considered GSM, a carrier must accept any GSM-compliant phone. So the GSM carriers don’t have total control of the phone you’re using.

That’s not the case with CDMA. In the U.S., CDMA carriers use network-based white lists to verify their subscribers. That means you can only switch phones with your carrier’s permission, and a carrier doesn’t have to accept any particular phone onto its network. It could, but typically, U.S. carriers choose not to.

Many Sprint and Verizon phones now have SIM cards, but that isn’t because of CDMA. The SIM cards are generally there for Sprint’s and Verizon’s 4G LTE networks, because the LTE standard also uses SIM cards. The phones may also have SIM slots to support foreign GSM networks as “world phones.” But those carriers still use CDMA to authenticate their phones on their own home networks.

3G CDMA networks (known as “EV-DO” or “Evolution Data Optimized”) also, generally, can’t make voice calls and transmit data at the same time. Once more, that’s an available option (known as “SV-DO” for “Simultaneous Voice and Data Optimization”), but one that U.S. carriers haven’t adopted for their networks and phones.

On the other hand, all 3G GSM networks have simultaneous voice and data, because it’s a required part of the spec. (3G GSM is also actually a type of CDMA. I’ll explain that later.)

So why did so many U.S. carriers go with CDMA? Timing. When Verizon’s predecessors and Sprint switched from analog to digital in 1995 and 1996, CDMA was the newest, hottest, fastest technology. It offered more capacity, better call quality and more potential than the GSM of the day. GSM caught up, but by then those carriers’ paths were set.

It’s possible to switch from CDMA to GSM. Bell and Telus in Canada have done it, to get access to the wider variety of off-the-shelf GSM phones. But Verizon and Sprint are big enough that they can get custom phones built for them, so they don’t see the need to waste money switching 3G technologies when they could be building out their 4G networks.

The Technology Behind CDMA vs. GSM
CDMA and GSM are both multiple access technologies. They’re ways for people to cram multiple phone calls or Internet connections into one radio channel.

GSM came first. It’s a “time division” system. Calls take turns. Your voice is transformed into digital data, which is given a channel and a time slot, so three calls on one channel look like this: 123123123123. On the other end, the receiver listens only to the assigned time slot and pieces the call back together.

The pulsing of the time division signal created the notorious “GSM buzz,” a buzzing sound whenever you put a GSM phone near a speaker. That’s mostly gone now, because 3G GSM (as I explain later) isn’t a time division technology.

CDMA required a bit more processing power. It’s a “code division” system. Every call’s data is encoded with a unique key, then the calls are all transmitted at once; if you have calls 1, 2, and 3 in a channel, the channel would just say 66666666. The receivers each have the unique key to “divide” the combined signal into its individual calls.

Code division turned out to be a more powerful and flexible technology, so “3G GSM” is actually a CDMA technology, called WCDMA (wideband CDMA) or UMTS (Universal Mobile Telephone System). WCDMA requires wider channels than older CDMA systems, as the name implies, but it has more data capacity.

Since its inception, GSM has evolved faster than CDMA. As I mentioned above, WCDMA is considered the 3G version of GSM technology. To further speed things up, the 3GPP (the GSM governing body) released extensions called HSPA, which have sped GSM networks up to as fast as 42Mbps, at least in theory.

Our CDMA networks, meanwhile, are stuck at 3.6Mbps. While faster CDMA technologies exist, U.S. carriers chose not to install them and have instead turned to 4G LTE to be more compatible with global standards.

The Future is LTE
The CDMA vs. GSM gap will close eventually as everyone moves to 4G LTE, but that doesn’t mean everyone’s phones will be compatible. LTE, or “Long Term Evolution,” is the new globally accepted 4G wireless standard. All of the U.S. carriers are turning it on. For more, see 3G vs. 4G: What’s the Difference?

The problem is, they’re turning it on in different frequency bands, with different 3G backup systems, and even, in the case of the new Sprint Spark network, using an LTE variant (TD-LTE) that doesn’t work with any other U.S. carrier’s phones. There are very few phones that support all of the carriers’ LTE bands.

Verizon has said it aims to start selling LTE-only phones in 2015, but for now, those will require special Verizon software to make voice calls, so that move won’t make it any easier to switch carriers with your phone. Even without CDMA, the CDMA philosophy of carrier control of your phone will remain intact.

A growing number of phones support all of these standards, but it can be hard to tell which ones. The iPhone 6, the iPhone 6 Plus and the Google Nexus 6 are the most flexible. iPhone 6 and 6 Plus units from AT&T, T-Mobile, and Verizon can all be used on all three carriers, but they lack Sprint’s special LTE bands. Sprint iPhones have all the bands, but Sprint has strict unlocking policies. Nexus 6 phones will technically work on all four carriers, but Sprint only allows phones purchased from Google or Sprint on its network.

HTC One (M8) and Samsung Galaxy S5 phones from Verizon will work somewhat on AT&T’s and T-Mobile’s networks, albeit with limited coverage because while they have CDMA, GSM and LTE, they don’t have all the frequency bands AT&T and T-Mobile use. Variants of those same models sold by AT&T and T-Mobile won’t work on Verizon at all, because they lack the CDMA radio needed for Verizon. It’s a mess.

So what does all of this mean for you? If you want to switch phones often, use your phone in Europe, or use imported phones, just go with GSM. Otherwise, pick your carrier based on coverage and call quality in your area and assume you’ll probably need a new phone if you switch carriers. Our Readers’ Choice and Fastest Mobile Networks awards are a great place to start.

Upcoming Battery Will Charge Phones And Electric Cars in Minutes

October 14, 2014 | by Lisa Winter

photo credit: Martin Abegglen via flickr

It takes about an hour to fully charge a cell phone, and the battery lasts about two to three years over 500 charge cycles. However, a new design could reduce charge time to only a few minutes and the battery is expected to last for 10,000 charge cycles over a 20 year lifespan. In addition to revolutionizing the technology that powers mobile devices, this has huge implications for the performance and longevity of batteries used in electric cars as well. The battery design was invented by Chen Xiaodong of Nanyang Technology University, and it was described in the journal Advanced Materials.

Rechargeable lithium ion batteries have been popularly used in electronic devices since the early 1990s, though the chemistry behind them has been studied since 1912. Traditionally, the batteries use a graphite anode (negative end) with a metal oxide cathode (positive end), along with an additive that helps facilitate electron exchange.

However, this new design replaces the carbon-based anode with a gel made of nanotubes of titanium dioxide. Titanium dioxide is spherical when found in nature, but converting it into the nanotubes allows it to charge much faster. This gel also replaces the need for the additive. Without the additive, there is more room within the battery for more of the gel, increasing the amount of energy it can store.

While many scientists have been trying to improve the performance and charging speed of batteries for years, the beauty of this new design is that it does not require developing something entirely new, rather it significantly improves what is already there. In fact, these modifications can be integrated into existing manufacturing procedures, making it much easier to bring this technology to market.

“Electric cars will be able to increase their range dramatically, with just five minutes of charging, which is on par with the time needed to pump petrol for current cars,” Chen Xiaodong said in a press release. “Equally important, we can now drastically cut down the toxic waste generated by disposed batteries, since our batteries last ten times longer than the current generation of lithium-ion batteries.”

The battery is the heart of the electric car and can cost around $5000 USD. By using a battery that can last 20 times longer than current technology, it will decrease the lifetime cost of the electric car, making them a more affordable and attractive option.

This new battery has already been patented and the team is currently in the process of trying to build a large prototype. Even ahead of the prototype, many in the electronics industry have expressed an interest in the new technology. The researchers believe that it could be available to consumers as early as 2016.

[Header image credit: Martin Abegglen via flickr, CC BY-SA 2.0]

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Apple Unveils iPhone 6, Apple Watch, Apple Pay

September 9th, 2014

(AP Photo/Marcio Jose Sanchez

(AP Photo/Marcio Jose Sanchez

 

By MICHAEL LIEDTKE and ANICK JESDANUN, AP Technology Writers
CUPERTINO, Calif. (AP) — For the first time in years, Apple’s iPhones weren’t the star of the show. Apple unveiled a smartwatch on Tuesday, a wearable device that marks the company’s first major entry in a new product category since the iPad’s debut in 2010.

The move is significant because of recent questions about whether Apple still has a knack for innovating following the 2011 death of co-founder Steve Jobs.

The device’s introduction upstaged the company’s two new, larger iPhones, which won’t just have bigger screens; they’ll have a new, horizontal viewing mode to take advantage of the larger display.

The iPhone 6 will have a screen measuring 4.7 inches, while the iPhone 6 Plus will be 5.5 inches. In both cases, app developers will be able to design apps that can be viewed differently when the phone is held horizontally.

Apple also introduced a system for using the phone to make credit card payments at retail stores.

Apple is turning to the past as it lays out its future. The company is holding the event at the Flint Center for the Performing Arts, the same venue where Jobs unveiled the industry-shifting Mac computer 25 years ago. The Cupertino, California, venue is near Apple’s headquarters.

As for the iPhones, which still represent the main source of Apple’s profits, larger models should help the company compete with Android devices.

Here’s what unfolded at Tuesday’s event:

LARGER iPHONES

The iPhone 6 will have a 4.7-inch screen, while the iPhone 6 Plus will be 5.5 inches. The screen resolution on the Plus version will be sharper than previous iPhones, at 401 pixels per inch rather than 326.

With the larger screen comes a new horizontal view of the home screen. Usually, icons are stacked vertically, even when the phone is turned horizontally. App developers will also have new tools to rearrange their content to take advantage of that larger screen.

The new phones aren’t as big as Samsung’s latest flagship phones – 5.1 inches for the Galaxy S5 and 5.7 inches for the Note 4 – but they will be large enough to neutralize a key advantage Samsung and other Android manufacturers have had.

Notably, Samsung’s Note phone isn’t getting bigger this year. Last year’s Note 3 was 5.7 inches. Instead, Samsung is emphasizing other hardware features, such as a sharper screen. It’s also releasing a model with a curved edge to display weather, time and other information on the side of the phone.

Apple says the new phones will be faster and have better battery life than previous versions. The phones will also have a new sensor, the barometer, to estimate how much you’ve climbed stairs, not just how far you’ve walked or run.

Of course, some people still use their phones to actually make calls. When there’s poor cellular reception, people will be able to make regular calls over Wi-Fi. The handoff between the two networks will be seamless. In the U.S., this feature will initially be available through T-Mobile.

The resolution on the camera is staying at 8 megapixels, while rival Android and Windows phones have been boosting that. The S5, for instance, is at 16 megapixels. However, the megapixel count is only one factor in what makes a good photo. Apple says it is putting in new sensors for better shots.

Apple is also improving a slow-motion video feature by allowing even slower shots. The camera will be able to take 240 frames per second, double what’s in last year’s iPhone 5s. Normally, video is at 60 frames per second.

The new phones will start shipping in the U.S. on Sept. 19, with advance orders to begin this Friday. Starting prices will be comparable to those in the past – $199 with a two-year contract for the iPhone 6 with 16 gigabytes of storage.

However, the step-up models will have double the memory than before – $299 for 64 gigabytes and $399 for 128 gigabytes. The iPhone 6 Plus phones will cost $100 more at each configuration.

MOBILE PAYMENTS

Apple is calling its new payment system Apple Pay.

You’ll be able to use your phone’s camera to capture a photo of your card. Apple will verify it behind the scenes and add it to your phone’s Passbook account so you can make payments at a retailer. Apple announced several merchants that will accept this system, including Macy’s, Whole Foods, Walgreens and Disney stores – and of course, Apple stores.

Many companies have tried to push mobile payment services, but none has caught on widely. Cook says that’s because the business models have been centered around companies’ self-interest instead of the user experience. The latter, Cook says, is “exactly what Apple does best.”

For security, the card number is stored only on the device. Each time you pay, a one-time card number is created to make the transaction.

A SMARTWATCH

The audience erupted with cheers as Cook proclaimed that he had, “one more thing.” It was how Jobs used to close his keynote addresses.

That one more thing was Apple’s upcoming smartwatch. It’s called the Apple Watch, rather than the iWatch that many people had been speculating.

Consumer electronics companies have yet to demonstrate a compelling need for smartwatches, while bracelets have largely been niche products aimed at tracking fitness activities. Apple’s device looks to change that.

Consider the company’s track record: Music players, smartphones and tablet computers existed long before Apple made its own versions. But they weren’t mainstream or popular until the iPod, iPhone and iPad came along. Under Jobs, Apple made those products easy and fun to use.

Cook says Apple had to invent a new interface for the watch because simply shrinking a phone wouldn’t work.

Much of the interaction would be through the dial on the watch, which Apple calls the digital crown. You use that to zoom in and out of a map, for instance, so you’re not blocking the screen, which would have occurred if you were pinching in and out to zoom.

Apple also worked with app developers to create new functionality. You’ll be able to unlock room doors at Starwood hotels or remind yourself where you parked your car with a BMW app.

The new watch will come in a variety of styles and straps, with a choice of two sizes. Watches from competing vendors have been criticized for being too big for smaller arms.

The watch will require one of the new iPhones or an iPhone 5, 5s or 5c. It will be available early next year at a starting price of $349.

NEW SOFTWARE

Though much of the attention has been on new gadgets, the software powering those gadgets is getting its annual refresh. Apple considers iOS 8 to be its biggest update since the introduction of the app store in 2008.

Existing iPhone and iPad users will be eligible for the free upgrade, too. Apple takes pride in pushing existing customers to the latest software, allowing app developers to incorporate new features without worrying about abandoning existing users. With Android, many recent phones can’t be upgraded right away because of restrictions placed by manufacturers and wireless carriers.

Among other things, iOS 8 will let devices work better in sync. For instance, it’ll be possible to start a message on an iPhone and finish it on an iPad. With an upcoming Mac upgrade called Yosemite, it’ll be possible to continue working on that same message on a Mac computer as well.

These handoff features will extend to the new Apple Watch, too.

The new software will be available to existing users on Sept. 17.

Closing out the event, U2 performed on stage before Cook made its new album, “Songs of Innocence” available for free to all customers of Apple’s iTunes.

Apple’s stock was up 1 percent to $99.36 in Tuesday’s late afternoon trading.

© 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

How Shazam Works?

Shazam application logo for the iPhone.

Shazam is the closest a cell phone can come to magic. Say you’re in a restaurant, a song comes on, and you can’t quite place the tune. In the past, your options were limited; you could try asking your spouse or the waiter for a clue, but that approach risked revealing your ignorance. (That’s “ Sex Machine,” dumb ass.) Shazam—which launched in the United Kingdom in 2002 as a call-in service and became widely known in the United States last year when it hit the iPhone—solves the dilemma in a few clicks. Press a button on your phone, and in seconds you’ll get the artist and song title. Other than playing video games, it’s the most useful thing you can do on your phone. Read more [+]

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