IGNOU BCA 4th sem Solved Assignment - Discuss the disadvantages of CDMA in wireless communication.

Discuss the disadvantages of CDMA in wireless communication.

Ans

Advantages of CDMA techniques:

 Efficient practical utilization of fixed frequency spectrum.

 Flexible allocation of resources.

 Many users of CDMA use the same frequency, TDD or FDD may be used

 Multipath fading may be substantially reduced because of large signal bandwidth

 No absolute limit on the number of users, Easy addition of more users.

 Impossible for hackers to decipher the code sent

 Better signal quality

 No sense of handoff when changing cells

 The CDMA channel is nominally 1.23 MHz wide.

 CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another.

 CDMA is compatible with other cellular technologies; this allows for nationwide roaming.

 The combination of digital and spread-spectrum modes supports several times as many signals per unit bandwidth as analog modes.

There are numerous handsets and service providers available in the market. Hence the buyers can choose from a variety of options.

They come with a variety of plans with cheaper call rates, free messaging facility, and limited free calls and so on.

The quality of calling in GSM is better and also better secured than CDMA.

A number of value-added services such as GPRS are making GSM a perfect choice.

The consumption of power is less in GSM mobiles.

With the tri-band GSM, one can use the phone anywhere around the world.

Disadvantages to using CDMA:

 As the number of users increases, the overall quality of service decreases

 Self-jamming

 Near- Far- problem arises

The per-unit charge on roaming calls is higher in GSM than in CDMA.

• Calls made through GSM mobiles can be tampered.

• If the SIM gets lost, one can lose all the data, if the same is not saved in the phone.

CDMA: CDMA is a proprietary standard designed by Qualcomm in the United States. CDMA is used as the second and third generations of the wireless communication. CDMA system operates on 800-MHz and 1900 MHz bands of frequency. In CDMA, first the voice signal is digitized & the resultant data is spread out over the entire frequency bandwidth. CDMA is a form of spread spectrum, which clearly means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range. Unlike GSM, it does not use the SIM card, rather gives a specific serial number to the handsets. CDMA systems use multiple access schemes, which are pioneered by Qualcomm.

There is no availability of variety of handsets in CDMA as in case of GSM for customers.

• They are incompatible with GSM handsets.

• CDMA has only 2 service providers to its credit & consumers have no option in case of their decreasing service level.

• The CDMA services have not yet got the facility for the web based services like messenger, downloading ringtones etc from websites.