1. Oct 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [ICI Analysis]
Date Submitted: [4 Oct 2005]
Source: [Rick Roberts] Company [Harris Corporation]
Address [Melbourne, Florida]
Voice:[ ], FAX: [],
Re: []
Abstract: [ICI Analysis]
Purpose: []
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.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
Rick Roberts, Harris Corp

2. TX Filtering Induced InterChip Interference (ICI) Analysis
Oct 2005
TX Filtering Induced InterChip Interference (ICI) Analysis
Rick Roberts, Harris Corp

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Oct 2005
Block Diagram
Code 1
Cross
Correlator
50% Excess BW RRC or
Guassian
50% Excess BW RRC or
Guassian
Auto Corr
Code 1
BPSK
MOD
BPSK
DEMOD
Low Pass
Low Pass
Cross
Correlator
Cross Corr
4.5 GHz LO
Code 2
Rick Roberts, Harris Corp
<author>, <company>

4. For this analysis I’ve used codes that have predictable properties.
Oct 2005
Summary
InterChip Interference (ICI) at the transmitter output occurs as the chipping rate approaches the Nyquist rate. The ICI significantly increases as the chipping rate is increased beyond the Nyquist rate.
This ICI impacts the transmitted code word, namely it degrades the cross correlation between previously nearly orthogonal code words and it increases the TX peak output power.
The approach presented in document a is hard to evaluate because the codes are random (due to the scrambler cover code), meaning they don’t have predictable cross correlation properties except over long average. This may be problematic if we are depending upon the code to support SOP via some measure of CDMA.
For this analysis I’ve used codes that have predictable properties.
Rick Roberts, Harris Corp

5. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Oct 2005
Code Words*
Source 1:
Source 2:
* Extracted from Document /153r6, 2-BOK codes for PNC1 and PNC2 (slide 10)
Rick Roberts, Harris Corp
<author>, <company>

6. Oct 2005 Root Raised Cosine Gaussian -3 dB BW is 500 MHz
Rick Roberts, Harris Corp

7. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Oct 2005
Chip Eye Patterns vs. Chipping Rate for Fixed 500 MHz BW
RRC
Gaussian
625 Mcps
500 Mcps
250 Mcps
100 Mcps
Rick Roberts, Harris Corp
<author>, <company>

8. Oct 2005
Rick Roberts, Harris Corp

9. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Oct 2005
Note: while actual results will vary with other nearly orthogonal codewords, they will show similar degradation
Rick Roberts, Harris Corp
<author>, <company>

10. Oct 2005
Conclusion
It is better that the chipping rate does not exceed the Nyquist rate as determined by the pulse forming network (chipping rate filter). To do so increases the TX peak power and also starts to impact the code properties (if any).
Rick Roberts, Harris Corp