  Quadrature Phase Shift Keying (QPSK) and Offset Quadrature Phase Shift Keying
(OQPSK) are two well accepted modulation techniques used in Code Division
Multiple Access (CDMA) system. The Pulse Shaping Filters play an important role
in digital transmission. The type of Pulse Shaping Filter used, and its
behavior would influence the performance of the communication system. This in
turn, would have an effect on the performance of the Mobile Communication
system, in which the digital communication technique has been employed. In this
paper we have presented comparative study of some performance parameters or
performance metrics of a digital communication system like, Error Vector
Magnitude (EVM), Magnitude Error, Phase Error and Bandwidth Efficiency for a
QPSK transmission system. Root Raised Cosine (RRC) and Raised Cosine (RC) Pulse
shaping filters have been used for comparison. The measurement results serve as
a guideline to the system designer to select the proper pulse shaping filter
with the appropriate value of filter roll off factor (a) in a QPSK modulated
mobile communication system for optimal values of its different performance
metrics.
