GSM Vs CDMA - A Comparative Study

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Comparison of Handsets Contd...

Disadvantages of CDMA Restricted roaming: CDMA cannot offer international roaming in all parts of the world. Qualcomm has been working on technology-neutral handsets, but these are not yet ready to be commercialised.28 High equipment cost, but offset by higher erlangs29 capacity: CDMA's hardware for its cell sites and stations is more expensive and complex than GSM's hardware. But on a per erlang (of traffic density) basis, CDMA's capital cost is quite competitive vis-a- vis that of GSM.30 Lack of smart cards: Since CDMA systems do not work on Subscriber Identity Modules (SIM) cards, reprogramming of the handset is necessary when a subscriber wishes to switch to a new handset or a different operator. This has a negative effect on the flexibility, convenience and delivery of the services offered. The Reusable Identity Modules (RUIM) launched recently under CDMA could overcome this shortcoming in the near future. 31

Phone heating up: These problems are interrelated. All cellular networks work through a connection between a cell phone and base station antennas. If all the antennas are not activated, the existing activated antennas try to cater to the needs of more subscribers than they should. When a CDMA handset realizes that a signal is weak, it tries to increase its power to reach the nearest tower signal. This leads to overheating of the phone. Moreover the attempt to meet the handset's demand for increased power drains the batteries.³²

Locked out: Sometimes, if two people with similar handsets stand close together, one handset may receive a stronger signal than the other. When on the move, a CDMA handset is connected to two towers for a short time-one from the tower of the cell where it exits and the other from the tower of the cell where it is enters. At times a user may find himself between two towers, one whose power is very strong and the other whose power is relatively weaker. To improve its contact with the stronger tower, the phone increases its power. But because it is under the influence of the tower with the weaker signal strength, it is forced to link up with the weaker tower. The phone's software is not able to make a transition and gets locked out. The only way out of this situation is to switch off the phone and restart it.³³

Advantages of GSM
Roaming Facility: GSM is used around the world by over 450 million subscribers. It provides an international roaming facility which permits users to use their phones all over the globe. Unlike GSM, a CDMA phone used in India will not work in France, Germany or any other European country. Since GSM phones use SIM cards, customers have access to data encryption facilities.³⁴

Less channel pollution: In most densely populated urban areas, cell sites are placed in close proximity. The user's phone receives signals from several base stations at once and none of these signals are dominant. This leads to a deterioration in CDMA voice quality. CDMA's coverage in sparsely populated areas is superior to that of GSM. In GSM, the adjacent cells use different frequencies. Hence deterioration in voice quality does not occur.³⁵

Conclusion

The wireless world is divided into two camps, GSM (used in a large part of Western Europe) and CDMA (used in North America and parts of Asia). Just two years before CDMA was introduced in Hong Kong in1995, European manufacturers chose to support the earlier technology, GSM's TDMA. Since most cellular users are in Europe and Asia, GSM is the more widely used technology. As of June, 2003, GSM had 793 million users worldwide while CDMA had 159 million users.

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28] www.mcommercetimes.com
29] A unit of traffic density. Erlang is CCS per hour, where CCS is hundreds of call seconds
30] www.mcommercetimes.com
31] BusinessWorld, April 21, 2003.
32] BusinessWorld, April 21, 2003.
33] BusinessWorld, April 21, 2003.
34] www.mcommercetimes.com.
35] www.geocities.com

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