Which is better? TDMA or CDMA?
I am curious to know which is better? TDMA or CDMA? Also, which is more reliable?...
- 01-09-2002, 12:54 AM #1
I am curious to know which is better? TDMA or CDMA?
Also, which is more reliable?
- 01-09-2002, 10:15 AM #2
- Join Date
- Oct 2001
Simple, CDMA is better than TDMA. TDMA is an older technology. Note that GSM is also a form of TDMA but utilizes a more complex implementation to improve upon TDMA's shortcomings. Also GSM uses a better CODEC than TDMA and therefore offers better sound quality.
Essentially, CDMA is a spread-sprectrum communication technique that offers better sound quality and handles more call volume than TDMA. Now mind you, the reason why CDMA carriers here in the US haven't blown the pants off of TDMA/GSM carriers is because there are other factors that come into play in determining how good cellular service is...such as the implementation and distribution of the number of appropriate cell towers for cellular signal coverage and to handle the call volume.
CDMA is also advantageous over GSM/TDMA because it can handle data transmissions better. If you're familiar with computer technology you will know that utilizing circuit-switched technology for mobile data tx is quite inefficient - well guess what? GSM/TDMA is based on circuit-switched technology whereas CDMA is packet-based, a more efficient approach for data tx.
TDMA has been able to hold its own because there are more TDMA towers right now than CDMA towers...especially in the cow country areas.
Note that current CDMA carriers will be upgrading to CDMA2000 (narrowband spread-sprectrum) and GSM/TDMA carriers will be upgrading to WCDMA (wideband spread-sprectrum). So essentially we will be seeing a convergence to some form of CDMA, albeit 2 different standards.
You may ask why then didn't CDMA carriers and GSM/TDMA carriers converge to a single standard (CDMA2000)? Politcs, Money, Politcs, Money...
Here's what someone also mentioned in another forum...
"I was speaking with a former Qualcomm executive (and major shareholder) who informed me that Qualcomm now individiually licensed CDMA to the European and American handset manufacturers (Nokia, Ericsson, Motorola and Siemens wanted a joint license - Qualcomm said no). Qualcomm suggested that the GSM carriers upgrade to CDMA2000 instead of WCDMA becuase, in their opinion, CDMA2000 will be a better technology (Qualcomm gets paid no matter what). The GSM carriers/manufacturers said no because they do not want interop. because of the manufacturing monopoly on GSM phones. Therefore - to keep interop between CDMA2000 and WCDMA, the Europeans are rolling out WCDMA even though by many it is considered inferior to CDMA2000. Nevertheless, GSM/GPRS/UMTS/EDGE has 90% of the global market, so we might see the same situation as we saw with IBM's OS/2 and Microsoft Windows....."
- 01-09-2002, 12:25 PM #3
- Join Date
- Oct 2001
- Central Valley NorCA
- Samsung SGH-I317 Note2
- Plantronics Discovery925, Garmin Nuvi 660
Now for the flip side of the coin....
First: Kenny's discussion is in whole completely correct. However....
I continue to hold that "better" is a matter of opinion and debate when it comes down to everyday use. "Better" to most users boils down to: Can I talk and have clear, secure calls? The answer for both TDMA and CDMA is Yes.
Read the second subheading on this article: http://whitehare.topcities.com/QA-Verizon.htm
- 01-09-2002, 8:54 PM #4
- Join Date
- Oct 2001
Korea’s wireless carriers are gearing up for the football (soccer) World Cup, to be held in Japan and Korea next summer. This large international event enables the Koreans to showcase their advanced CDMA technology. Korea is the only 'pure' CDMA market in the world. CDMA also forms the basis of 3G technology, and the Koreans hope their experience with CDMA will help them penetrate the international market for 3G technology, including the highly competative handsets market.
While global attention has focused on Japan’s DoCoMo and the recent launch of FOMA (its 3G W-CDMA network), the Koreans have been using a fast CDMA2000 1x network for more than a year. 1x is the CDMA version of GPRS, but is effectively a 3G technology. According to guidelines of the International Telecommunications Union (ITU), a 3G system must offer a minimum data rate of 144 kbps. CDMA2000 1x supports 153 kbps, enough for short video clips. Last month, at the Comdex in Las Vegas, Korea’s three leading mobile operators - SK Telecom, Korea Telecom Freetel (KFT) and LG Telecom - received the Andrew Seybold Price for their advanced CDMA 1x networks.
Penetration of mobile internet services in Korea reached 23%. The figure is expected to rise to 43% this year, the higest in the world. Koreans use their ‘1x’ phones to download not only weather reports and horoscopes but also video and CD-quality audio. Moreover, the Koreans operators are preparing the launch of CDMA2000 1x EV-D, a network that offers a theoretical speed of 2.4Mbps. The big three are working to have the new network operational before the World Cup in June next year. Unlike their European counterparts, Korean carriers have no problems procuring the required handsets for their advanced networks.
The rapid development of the wireless market in Korea illustrates that CDMA technology has several advantages. The migration from 2G via 2.5G to 3G network technology is faster and more economical than the migration from GSM via GPRS/EDGE to W-CDMA. The latter requires a near-total overhaul of the network, as well as new handsets. Moreover, GPRS is not compatible with W-CDMA. The migration of a CDMA network is largely a software upgrade, and CDMA handsets are backward compatible. 2.5G and 3G CDMA handsets can also be used on 2G networks.
The principle advantage of GSM is related to economies of scale. GSM has over 700 million users worldwide, versus about 100 million for CDMA. Deploying a GSM network is cheaper than a 2G CDMA network. However, most analysts agree that CDMA is superior to GSM. It makes more efficient use of the radio spectrum, and offers better data throughput. The latter becomes a factor when data replaces voice as the principle source of revenue, see Table 1 and Table 2.
CDMA is based on technology developed by Qualcomm, the American technology giant. Qualcomm’s hold on CDMA technology is somewhat comparable to Microsoft’s hold on the desktop PC. All suppliers of CDMA technology, both infrastucture and handsets, pay royaties to Qualcomm. The company receives approximately six dollars for each CDMA handset sold in the world. It stands to earn billions from the deployment of 3G networks.
Like Microsoft, Qualcomm has its detractors. The company fought a lengthy batlle with Ericsson about the validity of its patents on core CDMA technology. Nokia long refused to take a CDMA license, and has only recently capitulated. Qualcomm follows a hard-nosed licencing policy, and has even upset the Koreans, their most important allies. In October, seven Korean handset makers took Qualcomm to court for an agreement the Americans reached with Chinese CDMA handset makers.
The Koreans pay Qualcomm a standard 5.25% in royalties for handsets sold on the domestic market, and 5.72% for export models. When the agreement was signed, Qualcomm promised the Koreans 'the most favorable terms'. But the Koreans claim Qualcomm violated this promise by giving the Chinese a better deal. The Chinese pay 2.65% for handsets sold on the domestic Chinese market and 7% for export models. As a result, Koreans exporting CDMA handsets to China will have paid 4.35% more in royalties than their Chinese competitors.
Unfair and ungrateful, say the Koreans, if only because Korea has been the driving force in commercialising CDMA technology. It pioneered the design and production of CDMA handsets, enabling CDMA to develop rapidly. Korea’s handset makers also point out that they have already paid Qualcomm more than $758m in royalties. The Koreans export CDMA handsets to the US, South America, and markets in Asia. But China has always been regarded as the big prize, hence the anger of the Koreans. (The two largest handset makers, Samsung and LG, have not joined the lawsuit, but are negotiating with Qualcomm.)
The Chinese are currently buying some 40 million handsets a year. Most of these are GSM models, but China Unicom operates a regional CDMA network, which will be expanded to 300 cities this year. By 2004, the network will serve 50 million subscribers. When China migrates to 3G networks, the Koreans hope their experience with CDMA technology will give them an advantage on the Chinese market. China is likely to deploy three different 3G systems: W-CDMA, CDMA2000 and Chinese own TD-SCDMA.
Interestingly, large quantities of Korean CDMA handsets are being smuggled into China. Electronics shops in several Chinese cities diplay signs that say: 'CDMA, environmentally friendly, high voice transmission quality, low charge, phone plus number - all for 588 yuan ($71).' The price is a bargain for the Chinese. GSM phones are sold for about $120, while the price of legally important Korean CDMA handsets comes to about $240.
Unlike GSM phones, CDMA handsets have no SIM card. CDMA carrier China Unicom is aware of the illegal phones but allows them on the network to attract new subscibers. However, Qualcomm and Samsung are currently working on a R-UIM, (removable user identity module), a smart card similar to the SIM card. Handsets equipped with a R-UIM can be used on both GSM and CDMA networks. (Samsung produces both CDMA and GSM phones.)
Wireless technology has become critical to the Korean economy. This year, the export of wireless technology will exceed the value of the Korean car industry. The Korean goverment actively supports the industry. It is promoting the formation of a so-called CDMA belt, a far-reaching roaming agreement among CDMA carriers on both sides of the Pacific. The CDMA belt is meant to be a duplication of the large European GSM market.
SK Telecom has already signed an agreement with KDDI, the Japanese CDMA carrier. KDDI, with more than 10 million subscribers, is one of the world’s largest CDMA carriers. The Koreans are also negotiating with CDMA carriers in China, Taiwan, Thailand, Australia, the US, Canada and South America. The CDMA belt is expected to ultimately cover some 2 billion users.
The Koreans are also building bridges to the European GSM camp. Korean Telecom has developed a gateway for GSM phones, and SK Telecom and LG Telecom are currently negotiating roaming agreements with several European carriers. If all goes well, Europeans visiting the World Cup Soccer next summer will be able to use their GSM phones to call directly from Seoul to Europe. But they will have to do without a new feature available to users of CDMA. When a team scores a goal, Koreans can see an instant video replay on their 1x handsets.
- 01-10-2002, 9:32 AM #5
- 01-10-2002, 10:45 AM #6
- Join Date
- Oct 2001
By Jay Wrolstad
January 9, 2002
As for the head-to-head competition with CDMA2000, Nokia spokesperson Cherie Gary told Wireless NewsFactor that 75 percent of wireless carriers have already chosen the GSM/EDGE path.
The battle for 3G (third generation) wireless supremacy in the United States has been joined in earnest with the announcement by Nokia (NYSE: NOK) that the Finnish telecommunications giant has begun shipping commercial EDGE (enhanced data for GSM evolution) hardware to carriers in North America.
EDGE technology is based on the GSM (global system for mobile communications) standard and provides packet data transmission rates of up to as 473 kilobits per second (kbps), which is more than fast enough to support 3G features such as streaming media as well as increased voice capacity, Nokia said.
Volume deliveries have been made to Cingular Wireless and AT&T Wireless (NYSE: AWE), Nokia said, making these operators the first to implement the EDGE-based standard for eventually providing 3G services in the 800 MHz and 1900 MHZ spectrum bands to their customers.
"AT&T plans to begin offering commercial EDGE service this year, and Cingular has said its entire network will run on this technology by 2004," Nokia spokesperson Cherie Gary told Wireless NewsFactor.
The equipment being shipped now includes GSM/EDGE radios, baseband units and some software, which will undergo testing by the carriers, she said. Shortly after GSM/EDGE rolls out in the U.S., Nokia plans a launch in Europe.
Race To Upgrade
But while Cingular and AT&T Wireless are committed to EDGE, competitors such as Verizon Wireless (NYSE: VZ), Sprint PCS (NYSE: PCS) and other U.S. carriers have invested heavily in Qualcomm's (Nasdaq: QCOM) CDMA2000 (code division multiple access) technology for their next-generation networks. And Qualcomm announced a week ago that it had begun shipping an array of 3G products based on its CDMA2000 1X technology platform.
Who will gain the upper hand will not be known for years, until the networks are up and running and the necessary handsets are widely available. "They each have strengths and weaknesses, but the upgrade probably will be smoother with CDMA2000," David Berndt, director of wireless mobile technologies at the Yankee Group, told Wireless NewsFactor.
To reach the 3G goal, Berndt said, GSM carriers such as Cingular and AT&T Wireless require a software upgrade from GPRS (general packet radio service) to EDGE and then must move to UMTS (universal mobile telecommunications system). CDMA2000 1X, he said, has been deployed in Korea and has been working well, while GPRS has experienced some problems in Europe.
"Globally, CDMA has the edge," Berndt said. Carriers such as Cingular and AT&T Wireless have begun rolling out GSM networks, so they are committed to staying with the technology, he added.
Nokia Claims Advantage
Still, Nokia contends that the deployment of EDGE by major carriers in the United States and elsewhere around the world make it the key to launching 3G services in the global wireless industry.
"EDGE allows carriers to begin offering 3G services well ahead of other competing technologies. It will enhance the spectrum efficiency of current GSM networks three- to fourfold and will enable data rates up to 473 kbps for GSM/GPRS subscribers," said Timothy Eckersley, senior vice president at Nokia Networks.
More efficient use of radio spectrum by GSM/EDGE allows more efficient use of available spectrum by carriers, Nokia said -- and as part of a global standard, EDGE offers the benefits of global roaming and economies of scale provided by GSM.
As for going head to head with CDMA2000, Gary pointed out that the GSM/EDGE path has been chosen by 75 percent of wireless carriers, giving it an advantage with global roaming capabilities and greater wireless terminal options.
"The GSM 3G phones are more affordable as well, costing $10 to $20 less than CDMA-enabled phones, which does not sound like much, but in volume is a substantial difference," she added.
Network Rollouts This Year
While terms of the EDGE technology agreements with Cingular and AT&T Wireless were not revealed by Nokia, Cingular last month said it had reached a US$1 billion deal with Nokia for GSM/EDGE infrastructure equipment as part of a $3.5 billion nationwide network upgrade.
Cingular plans to provide nationwide GSM/EDGE services, including GPRS, beginning this year. AT&T Wireless also has announced its intentions to deploy the technology in the second half of 2002. That may well be a realistic goal, given that Nokia and AT&T Wireless already have completed the first live EDGE data call using EDGE/GSM technology.
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