Computeruser.com
Latest News

Standards alphabet soup

Standards like CDMA and GSM are confusing, but all the letters could soon spell ‘wireless.’

The tech world is rife with initials, as anyone with a PDA, PS2, and MP3 player can tell you. For those paying attention to the cellular world, however, the tangle of terminology can make a spin through CompTIA’s CDIA+ section seem like a snap. As competing standards evolve, CDMA, TDMA, and GSM have become only the most basic shorthand, with an alphabet soup of new abbreviations bubbling up in the past few years, including GPRS, 3GSM, WCDMA, CDMA2000, and 3G.

Most users of cell phones and other mobile devices don’t actually need to know CDMA from INXS, and usually, they don’t want to know. They just like to push the buttons and have the right connections made. But these standards do affect us, because they’re closely associated with carrier coverage, capabilities, and phone availability. Also, as much of the world veers in the direction of GSM, those in the United States who embrace CDMA will find themselves continuing to face issues of interoperability and cost as the next generation of technology speeds ahead.

The adoption of wireless devices, and the continued shrinking of the globe as worldwide communication is necessary, should heat up the standards battle even more. This standards war might cause a peace-loving technologist to plead, “Can’t we all just get along?” The answer, unfortunately, might be: Not in the near future.

Standard definition

To understand some of the issues facing communications providers, it’s necessary to untangle a little of the terminology and look at how so many paths got created.

In the 1980s, when cellular networks were first introduced, the channel allocated for a call used an analog radio transmission technology called AMPS (Advanced Mobile Phone System). As the technology improved, carriers began to deploy digital technology, but this required new tactics. Thus, different ways to deal with the problem sprouted into being.

Time Division Multiple Access (TDMA) is a bit like a timeshare condo, but without the housekeeping charges. Three calls can use the same frequency at the same time, and each call gets a time slot for use of the full channel, with rotation of the calls to prevent channel hogging. Data and voice information are stored and sent in packets based on whose time slot it is, but because the pattern of rotation repeats so quickly, there’s little delay. This neat timeshare trick sped up the cellular world considerably. Where an analog-based network can handle about 100 calls simultaneously, a TDMA-based network can handle around 1,000 calls at once.

As TDMA was becoming standardized, Qualcomm whipped up Code Division Multiple Access (CDMA) for the military, to allow soldiers to better communicate on the battlefield. It assigns each call a unique code, and uses a low-power signal across a wide frequency so each call can move quickly through different frequencies. Now widely used in the commercial sector, CDMA uses whatever bandwidth it can find, and boosts the number of simultaneous calls handled to 10,000.

Developed as an open standard, Global System for Mobile communications (GSM) caught on quickly in Europe, where it’s still far and away the primary standard. It uses parts of both TDMA and CDMA by separating calls into time slots and also assigning a unique code to each call. According to the GSM Association, its 690 second- and third-generation wireless network operators provide services to more than 800 million customers in over 192 countries, accounting for approximately 71 percent of the total digital wireless market. The association expects that GSM will see its one billionth customer by the end of 2003.

Next gen networks

As TDMA wireless networks stumble toward extinction, GSM and CDMA are the big two of the standards world, from which all others have been born. And the next generation standards are growing up fast.

Usually called 3G for third generation, the new crop of standards is focused on wireless data capability. Here’s where it gets a little tricky, because the abbreviations used for the other standards have, excuse the pun, standard meanings. However, 3G is a term bandied about loosely, and made even more confusing by the amount of hype given to it. Also thrown into the mix is 2.5G, considered to be the transition between the three main standards and their futuristic kin. Basically, most carriers are currently in the process of rolling out 2.5G, with 3G plans straight ahead.

For this endeavor, newer standards have been trotted out. GSM’s evolution is the 2.5G option General Packet Radio Service (GPRS), a 3G option called 3GSM, and a more advanced delivery method known as EDGE for Enhanced Data rates for GSM Evolution. CDMA now boasts two spunky kids, the 2.5G CDMA2000, and the 3G Wideband CDMA, or WCDMA. Sometimes the former will be referred to by the name given in its first phase, CDMA2000 1x.

Got all that? Good. Now here’s why you shouldn’t worry, but you should care.

Network news

For most consumers, cellular and wireless standards are in the background, like picking up the phone and dialing long distance without thinking of whether Sprint or MCI is handling the call. When it comes time to buy a phone or another mobile device, users’ interest raises, however. Users are rightly careful to lock into a network that will fit their needs not only today, but in future evolutionary steps of the standards.

“From a consumer viewpoint, there are a couple of reasons to care about standards,” says Tom Rosch, general partner in information technology at venture capital firm InterWest Partners. “The main thing is that in some areas, there’s crappy coverage. This can be caused by which carrier you have and what kind of upgrades they’re making to the network.” Updating equipment from 2G to 3G by way of 2.5G isn’t cheap, and carriers are sometimes rolling out their upgrades slowly, causing customers to groan about dropped calls and spotty connections.

There is also the future to consider, according to Rosch. He says, “You want to get new features like data over your cell phone, you want e-mail access, you want to be able to match movies and make videos.” Which carrier a consumer chooses for these options will depend on service availability, which in turn depends on the standards being utilized by each carrier.

But the main quibble about different standards is a loud groan from a small minority: the people who want their phones to work anywhere in the world. These traveling few grumble about how GSM in Europe and Asia means one phone while the CDMA-focused United States requires another. There are dual-band phones that work on the slightly different GSM/GPRS networks in both Europe and the States, but none work on both CDMA and GSM networks. Work is being done on developing a phone with multiple chipsets, but it’s still at least a year away by conservative estimate.

Increasingly, as some carriers like AT&T grow their GSM network in the United States, the problem of CDMA versus GSM may worsen. Also, CDMA is getting a foothold in Asia and Australia, which means that even though GSM leads the pack by an overwhelming margin now, the potential for a world of more mixed standards could cause more headaches than hurrahs.

Also at issue is the future of technology decisions, says Chris Conley, professor of product design and development at the Illinois Institute of Technology. He says, “In the U.S. we have CDMA, TDMA, and GSM all competing with poor interoperation. In addition, each of these standards is evolving to allow data to be served. This is one area where the U.S. consumer does not know what they’re missing, or what is possible with mobile technology. We’re still primarily a voice market with little messaging and data use. Europe and Asia have a different balance. Much more messaging and data with reduced voice usage.”

However, this doesn’t necessarily lead to two different technology paths, with standards driving how devices get developed and where. Conley says, “Since mobile technology is still relatively young and progressing rapidly, carriers associate their technology with features relevant to users. But in the end, which could be 10 years away, we won’t care.” He cites the example of automobiles, which used to be judged and purchased based on their technology, but now are chosen instead according to brand, options, and car type.

Future think

When Conley says the end of the standards differences could be as much as 10 years away, he isn’t kidding. Even now, the slow rollout from 2G up to the halfway mark is taking longer than carriers anticipated.

“It’s going a lot slower than people thought it would,” says Rick Osterloh, senior product manager for Good Technology, a developer of wireless software, services and handhelds. “The key thing that the carriers are doing is taking an existing cellular network structure and adding another component that enables data to go over the same spectrum as voice.” He adds that making sure the physical infrastructure, the steel towers dotting the countryside, are in shape is only the first part of the process. Next comes making sure the networks are reliable and testing applications, and that only brings a carrier up to 2.5G.

Osterloh says, “The really substantial upgrade will be to 3G. CDMA does have some technical advantages for this upgrade, but all carriers will face technology and economic risks.” According to New Jersey-based Probe Research, about 150 2.5G networks and five 3G networks are in commercial service. However, that leaves hundreds more that have to upgrade.

Ray Hegarty, an analyst for San Francisco-based technology research firm The451 says the process could take more time because of the continual legislative wrangling that has become commonplace in the communications industry. Also, carriers have yet to figure out proper billing procedures, which may seem minor, but could add quite a bit of time onto the march to 3G. Hegarty says, “The carriers don’t have the sophistication, they don’t have the billing back end in place. They’re far from being able to integrate their databases in a way that will enable them to pull this off. It’s going to cost them a lot of money to do it, and at the moment, capital expenditures are something of a problem.”

Despite the stumbling blocks thrown into the road to better wireless service, some are still optimistic that multiple standards and competing technologies won’t stop progress. Probe Research predicts that carriers will make the investment, because offering 3G capability will increase the amount of revenue per customer in the long run. And many believe that the number of potential customers is staggering. Probe suggests that the market for 2.5G and 3G packet-data infrastructure will almost double by 2004.

The result of the TDMA/GSM/CDMA tussle is a resounding “wait and see,” unfortunately. As carriers expand their reach and ask technicians to scramble up steel towers, consumers long for the time when 3G is as prevalent as those MP3s and PDAs. After all, just imagine being able to get INXS or U2 MP3s via 3G–now, that will be a red-letter day.

The skinny on the standards

CDMA

Speed: Around 14.4Kbps

Carriers: Verizon Wireless, Sprint PCS, Sprint Wireless

Features: Originally called IS-95.

GSM

Speed: Between 9.6Kbps and 38.4Kbps

Carriers: AT & T Wireless, Cingular Wireless, T-Mobile

Features: Most used standard and growing fast.

3GSM

Features: The generic term used for the next generation of mobile communications services. The concepts for 3GSM services are currently being developed across the industry and by global groups such as the Third Generation Partnership Project (3GPP).

TDMA

Speed: About 9.6Kbps

Carriers: Cellular One, US Cellular, SunCom. Depending on phone, some compatibility with AT&T Wireless and Cingular Wireless.

Features: Although GSM uses part of this standard, it’s slowly being phased out by its more prevalent cousins.

GPRS

Speed: Theoretical data rates over 170Kbps

Carriers: AT & T Wireless, Cingular Wireless, T-Mobile

Features: Adds packet data capabiity, and the ability to use more than one of the GSM time slots at a time.

CDMA2000

Speed: Up to 614Kbps. Data rate of 1X version is 144Kbps.

Carriers: Ericsson

Features: Also known as 1X, or 1XEV-DO. This enables operators with existing IS-95 systems to double system capacity.

WCDMA

Speed: Up to 2Mbps

Carriers: Ericsson

Features: “W” stands for wideband. The information in a CDMA transmission is digitally mixed with unique coding and spread out ver the entire 1.25 MHz carrier.

EDGE

Speed: Up to 48Kbps per time slot predicted, theoretical maximum of 384Kbps, assuming all eight time slots are used for data and none for voice.

Features: Based on a new modulation scheme called eight-phase-shift keying. It allows a much higher bit rate, and is also the type of modulation used in WCDMA, so EDGE can be used by operators who fail to win WCDMA spectrum.

Leave a comment

seks shop - izolasyon
basic theory test book basic theory test