subject: difference between CDMA and GSM batteries? - T-Mobile [print this page] difference between CDMA and GSM batteries? - T-Mobile
Code division multiple access (CDMA) is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply CDMA), which use CDMA as an underlying channel access method. One of the basic concepts in data communication is the idea of allowing several transmitters to send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). This concept is called multiplexing. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. CDMA is a form of spread-spectrum signaling, since the modulated coded signal has a much higher data bandwidth than the data being communicated. An analogy to the problem of multiple access is a room (channel) in which people wish to talk to each other simultaneously. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different languages (code division). CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can communicate. GSM (Global System for Mobile Communications: originally from Groupe Spcial Mobile) is the most popular standard for mobile telephony systems in the world. The GSM Association, its promoting industry trade organization of mobile phone carriers and manufacturers, estimates that 80% of the global mobile market uses the standard GSM is used by over 1.5 billion peopleacross more than 212 countries and territories This ubiquity means that subscribers can use their phones throughout the world, enabled by international roaming arrangements between mobile network operators. GSM differs from its predecessor technologies in that both signaling and speech channels are digital, and thus GSM is considered a second generation (2G) mobile phone system. This also facilitates the wide-spread implementation of data communication applications into the system. The GSM standard has been an advantage to both consumers, who may benefit from the ability to roam and switch carriers without replacing phones, and also to network operators, who can choose equipment from many GSM equipment vendors GSM also pioneered low-cost implementation of the short message service (SMS), also called text messaging, which has since been supported on other mobile phone standards as well. The standard includes a worldwide emergency telephone number feature (112). Newer versions of the standard were backward-compatible with the original GSM system. For example, Release '97 of the standard added packet data capabilities by means of General Packet Radio Service (GPRS). Release '99 introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution (EDGE). T-Mobile is a German provider, owned by Deutsche Telekom. It operates several GSM networks in Europe and the United States. T-Mobile also has financial stakes in mobile operators in Central and Eastern Europe. Globally, T-Mobile has some 150 million subscribers, making it the world's eighth largest mobile phone service provider by subscribers and the third largest multinational after the United Kingdom's Vodafone and Spain's Telefnica. T-Mobile UK has recently become part of a joint venture with France Telecom's mobile network provider, Orange U.K.; together they make the UK's largest mobile operator, called Everything Everywhere. Based in Germany, T-Mobile is present in ten other European countries (Austria, Croatia, Czech Republic, Hungary, Macedonia, Montenegro, the Netherlands, Poland, Slovakia and the United Kingdom) as well as the United States. In late 2005, Deutsche Telekom attempted to acquire rival mobile network operator O2, but was beaten by Spain's Telefnica. In March 2008, the company announced its plan to acquire Siemens Wireless Modules (now known as Cinterion Wireless Modules) as part of the JOMA consortium. The Siemens Wireless Modules spin off to Cinterion Wireless Modules was concluded on 1 May 2008. for more info - Mobile question and answers
