CDMA (Code division multiple access)

GSM refers to Global System for Mobile communications while

CDMA refers to Code Division Multiple Access.

Both are two diffrent technologies in Telcommunications and

behave diffrently in terms of giving voice and data

services to the customer.

Though GSM is globally used teschnology - CDMA technology

has more benefits in terms of call clarity, faster data

speeds etc while GSM covers most of the network areas and

has got variety of handsets to choose from, people prefer

this technology.

Other than these 2 technologies we have other technologies

like TDMA, WCDMA etc

Reverse link is weak in CDMA because of use of PN Long codes compared to Walsh codes in the forward link. Since, walsh codes are perfectly orthogonal in nature there is less interference in the forward link. PN long codes on the other hand are non-orthogonal in nature. However, we cant use walsh codes for the reverse link as it may seem from the above as the best possible solution. This is because walsh codes are very small in number (64/128/512 max), and hence are not sufficient for identification of large number of users in the reverse link for which the PN long codes are employed.

1> cdma stands for code division multiple access; its

frequency 800 mhz and 1900 mhz

2>channel bandwidth 12mhz with 1.25mhz for spread spectrum

3>in cdma we allocate a unique code to the user separately

and allocate the total bandwidth to the user.

4>in gsm we divide the bandwidth into many time slots and

allocate each time slot to the user.

1) For 1xRTT has four forward and two reverse channels,

where as in EVDO channel structure is different.

2) 1x RTT supports upto 153.2 kbps of data, where as EVDO

supports upto 3.1Mbps.

3)In 1x RTT during measurement pilot power ratio , Traffic

power ratio are also taken into consideration; where as in

EVDO FTAP , RTAP with Slots are taken into consideration