## EECS CSPL SEMINAR SERIES

FALL TERM 1996

Sangsin Na
# Sangsin Na

### Department of Electronics Engineering, Ajou University,
Korea

### sangna@madang.ajou.ac.kr

Friday, October 25, 1996

1:30-2:30 pm

1504 G. G. Brown Building

### Intersymbol Interference Due to Mismatched Raised Cosine
Filters and the Taylor-Series Approximation

Abstract -

The talk presents and discusses two results on
the effect of sampling-time jitter
at the receiver on the bit error probability in
digital modulation over an additive Gaussian noise channel.

The first result is regarding the bit error probability
of a digital communication system with mismatched
square-root raised cosine filters at the transmitter and
the receiver, in which the filters have different roll-off
factors; the second is the Taylor series approximation
of the bit error probability in the case of matched
raised-cosine pulse-shaping filters.

The principal result is that the roll-off factor mismatch
incurs intersymbol interference even when the sampling time
is perfect and that the mismatch intersymbol interference seems
negligible when the signal-to-noise
ratio is moderate (around 6 dB) and it grows
as the signal-to-noise ratio increases. However, the mismatch
loss is within 0.5 dB of the optimum bit error probability at
around 1.0E-8.

In the case of the matched square-root raised cosine filters, an
approximation formula for the bit error probability is derived.
It shows how the factors affect the bit error probability.
This formula becomes more accurate for smaller jitter and a bigger
roll-off factor.

Biosketch -

Sangsin Na is a Professor in the
Department of Electronics Engineering,
Ajou University,
Suwon 442-749, Korea.
He received his BS in EE, Seoul National University,
MS in ECE, University of Michigan, and his
Ph.D. in EE:Systems, Univ. of Michigan.

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