1. 12 March 2001
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [OQPSK Cross-Talk Characteristics]
Date Submitted: [12 March 2001]
Source: [Rick Roberts] Company [XtremeSpectrum]
Address [8133 Leesburg Pike, Vienna, Va ]
Voice:[ ], FAX: [ ],
Re: [ revision zero]
Abstract: [Discussions the cross talk nature of OQPSK]
Purpose: [Support TG PHY Committee]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
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2. I Q Simplistic Example of Cross-Correlation Problem in OQPSK
12 March 2001
Consider OQPSK transmission in a simple complex impulse response channel I2 I3 I5
QI2
QI3 I
QI1
QI4
QI5 I1 I4
Notice the Cross Talk Between the I and Q Channels and the Locate of the Zero Crossing Q1 Q4 Q5
IQ2
IQ3
IQ5 Q
IQ1
IQ4 Q2 Q3
Now cross correlate between the two channels “at the respective sample time for each arm”
Xqi = E[Q1*QI1 + Q2*QI2 + Q3*QI3 + Q4*QI4 + Q5*QI5]
Xiq = E[I1*IQ1 + I2*IQ2 + I3*IQ3 + I4*IQ4 + I5*IQ5]
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3. 12 March 2001
Now time align the I and Q channels as an OQPSK receiver would do using a time delay I2 I3 I5
QI2
QI3 I
QI1
QI4
QI5 I1 I4
Notice the Cross Talk Between the I and Q Channels and the Locate of the Zero Crossing Q1 Q4 Q5
IQ2
IQ3
IQ5 Q
IQ1
IQ4 Q2 Q3
Notice that the cross correlation value has changed! Statistically this is not the same signal! It is this change in statistics that I believe is causing problems for Jayhen. - Rick
Now cross correlate between the two channels “at the sample time”
Xqi = E[Q1*I1 + Q2*I2 + Q3*I3 + Q4*I4 + Q5*I5]
Xiq = E[I1*Q1 + I2*Q2 + I3*Q3 + I4*Q4 + I5*Q5]
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