MOBILE TECHNOLOGIES - GSM AND CDMA

GSM (Global System for Mobile Communications)

It 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 more than 3 billion people across over 212 countries and territories. Its ubiquity enables roaming of international conditions between mobile phone operators, providing subscribers the use of their phones in many parts of the world. GSM differs from its previous technologies in that both signaling and speech channels are digital, and thus GSM is considered a 2G mobile phone system. This also facilitates the wide-spread implementation of data communication applications into the system. The ubiquity of implementation of 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 text messaging (SMS) and newer versions (Release 1997) General Packet Radio Service (GPRS) (standard added packet data capabilities) and (Release 1999) Enhanced Data Rates for GSM Evolution (EDGE) (higher speed data transmission)

CDMA (Code Division Multiple Access)

It is a channel access method utilized by various radio communication technologies. It is 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 sharing a bandwidth of frequencies in different categories. This is called multiplexing. It employs spread-spectrum technology and a special coding scheme (where code assigned to each) to allow multi users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, where (FDMA) Frequency-division multiple access divides the same 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 communicate with each other. Because of this confusion, In order to avoid this people could take turns speaking (time division), at different pitches (frequency division) or in different languages (code division). CDMA is analogous to the last example where people speaking the same language can understand, but not the other. Likewise, in radio CDMA, each group of users, a shared code is given. The same channel can be occupied by many codes, but users who only associated with a particular code can understand each other.

COMPARING CDMA / GSM – which is better?

Advantages of CDMA:

Ø Cellular communications security increased

Ø Simultaneous Conversations

Ø Efficiency increased, mean to carrier can serve more subscribers

Ø Smaller Phones

Ø Power requirements is less and cell-to-cell coordination needed by operators is also less

Ø Extended reach – Beneficial to rural users situated very far from cells

Disadvantages of CDMA

Ø Due to its proprietary nature, all of CDMA’s flaws are not known to the engineering society

Ø CDMA is a relatively new, and the network is not as mature as GSM

Ø CDMA cannot offer international roaming, a large GSM advantage

Advantages of GSM:

Ø GSM is already used worldwide with over 450 million subscribers

Ø International roaming permits subscribers to use one phone throughout Western Europe. CDMA will work only in ASIAN countries but not in European countries like France, Germany, U.K

Ø GSM is mature, started in mid - 80’s. It means a more stable network with vigorous features. CDMA is still building its network

Ø GSM – engineers cut their teeth on the technology, creating unconscious preference

Ø The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM – m – commerce advantages

Ø A MORE ELEGANT WAY TO UPGRADE TO 3G, says Strategies Group senior wireless analyst Adam Guy.

Disadvantages of GSM

Ø Lack of access to escalating American market

Today, the battle between CDMA and GSM is cluttered. One point – Europe favored – GSM and North America favored CDMA, the advantage of one over the other has unclear as major carriers like AT&T wireless begin to support GSM, and recent trials even showed compatibility between the two technologies

GSM still holds the upper hand. GSM users – over 456 million and CDMA users – over 82 million