1. Explicit feedback with sounding packet
May 2006
doc.: IEEE /1524r0
September 2006
Explicit feedback with sounding packet
Date:
Authors:
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Deric Waters, Texas Instruments
Deric Waters, Texas Instruments

2. Flaws in Pilot Definition for MCS 32
September 2006
Flaws in Pilot Definition for MCS 32
Pilot values for the second space-time stream are undefined.
Text and equation (20-55) [D1.0] are inconsistent.
Pg. 209, line 5-6 [D1.0], “The pilot values are the same as the values on bins -21, -7, 7, 21 in the 20MHz mode, repeated on the 6 negative and positive bins and rotated in the upper bins.” Implies that pilot values depend on the OFDM symbol number, n.
(20-55) defines pilot values from The pilot values are the same for every OFDM symbol (i.e. not a function of n).
Deric Waters, Texas Instruments

3. Eq (20-55) September 2006 , where , as defined in Clause 17.3.5.9.
Deric Waters, Texas Instruments

4. Pilot Values in 20 MHz Transmission
September 2006
Pilot Values in 20 MHz Transmission
NSTS
iSTS 1 -1 2
n is the OFDM symbol number.
Deric Waters, Texas Instruments

5. Two Possible Solutions
September 2006
Two Possible Solutions
Modify equation to implement the text.
HT duplicate and 20 MHz HT modes have the same pilot values (depends on the OFDM symbol number).
Modify the text to match the equation.
HT duplicate mode (non-STBC) has same pilot values as non-HT duplicate (independent of the OFDM symbol number).
Both solutions require defining the pilot values for the STBC mode.
Deric Waters, Texas Instruments

6. Straw Poll #1 Yes: No: Don’t care:
September 2006
Straw Poll #1
Should MCS 32 with NSTS=1 have the same pilot values as non-HT duplicate (same as legacy 20 MHz transmission)?
Yes:
No:
Don’t care:
Deric Waters, Texas Instruments

7. Straw Poll #2 For MCS 32 with STBC,
September 2006
Straw Poll #2
For MCS 32 with STBC,
Pilot values of first space-time stream should match pilot values from non-HT duplicate mode. Pilot values of second space-time stream are a static orthogonal sequence.
Pilot values of both space-time streams match the pilot values of 20 MHz transmission.
Option 1:
Option 2:
Don’t care:
Deric Waters, Texas Instruments