Optical Communication Components and Subsystems
ECE 565
Spring 2005
Homework 7
Assignment due date: Monday, April 4, 12:30 PM
From the text: Problems 4.9, 4.12, 4.13, 4.16, 4.17
Special Problem: see next page
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View Full DocumentSpecial Problem 1.
This problem is related to intersymbolinterference (ISI) noise in onoﬀ
keying, direct detection optical communication. Consider a train of
n
optical pulses arriving at an
optical receiver. These pulses represent
n
bits of binary information (consisting of zeros or ones).
Let
P
(
t
) denote the received optical power as a function of real time,
t
. If each bit is allowed to
occupy
T
B
seconds and if all types of pulse broadening in the ﬁber are neglected, then we can
represent
P
(
t
) as
P
(
t
) =
n
X
k
=0
P
k
q
(
t

kT
B
)
,
(1)
where for each
k
,
q
(
t

kT
B
) is a rectangular pulse of unity hight that starts at
t
=
kT
B
and ends
at
t
= (
k
+ 1)
T
B
. For simplicity, assume that for each
k
, the pulse intensity
P
k
is either 0 W or 1
W, corresponding to the absence or presence of a pulse, respectively.
According to a shotnoise model for the photocurrent, the receiver photocurrent (output)
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 Spring '11
 Rahmir
 Photon, Signaltonoise ratio, pulse, Rectangular function

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