1. Cyclic Shift For More Than 4 Antennas in Non-VHT Portion
July 2010
doc.: IEEE /0916r0
July 2010
Cyclic Shift For More Than 4 Antennas in Non-VHT Portion
Date:
Authors:
Yung-Szu Tu, et al., Ralink Tech.
Yung-Szu Tu, et al., Ralink Tech.

2. Outline Introduction Cyclic shift in VHT-SIGA
July 2010
Outline
Introduction
Cyclic shift in VHT-SIGA
Cyclic shift for more than 4 antennas
Straw polls
Yung-Szu Tu, et al., Ralink Tech.

3. July 2010
Introduction
Cyclic shift, i.e. CSD value, for up to 4 antennas in L-STF, L-LTF, and L-SIG has been defined in the spec. framework [1]
The same as CSD values for the non-HT portion of the packet defined in Table 20-8 of Std n-200
CSD values for more than 4 antennas in L-STF, L-LTF, and L-SIG is TBD [1]
CSD values in VHT-SIGA is not determined yet
Yung-Szu Tu, et al., Ralink Tech.

4. Cyclic Shift in VHT-SIGA
July 2010
Cyclic Shift in VHT-SIGA
In n [2], CSD values in HT-SIG are the same as L-STF, L-LTF, and L-SIG
Although CSD values in L-STF, L-LTF, and L-SIG are TBD for more than 4 antennas, i.e. transmit chains, CSD values in VHT-SIGA can be the same as L-STF, L-LTF, and L-SIG of n for up to 4 antennas
Yung-Szu Tu, et al., Ralink Tech.

5. Cyclic Shift for More Than 4 Antennas
July 2010
Cyclic Shift for More Than 4 Antennas
To avoid unintentional and undesired beamforming, cyclic shift is used
In [3], it is pointed out that large CSD values would result in SIGNAL field errors
Therefore, the CSD values in non-HT and HT-SIG portion in n are different than the rest
Within the interval of 200ns
Yung-Szu Tu, et al., Ralink Tech.

6. Cyclic Shift for More Than 4 Antennas (cont.)
July 2010
Cyclic Shift for More Than 4 Antennas (cont.)
We propose CSD values for more than 4 antennas are also within the interval of 200ns
For 6, 7, and 8 antennas, there are several choices, but we need further investigation to choose the best one
For number of TX chain =5:
Number of TX chain
CSD1
CSD2
CSD3
CSD4
CSD5 5
0ns
-50ns
-100ns
-150ns
-200ns
Yung-Szu Tu, et al., Ralink Tech.

7. Cyclic Shift for More Than 4 Antennas (cont.)
July 2010
Cyclic Shift for More Than 4 Antennas (cont.)
For number of TX chain =6:
Number of TX chain
CSD1
CSD2
CSD3
CSD4
CSD5
CSD6 6
0ns
-25ns
-50ns
-75ns
-100ns
-125ns
-150ns
-200ns
-175ns
Yung-Szu Tu, et al., Ralink Tech.

8. Cyclic Shift for More Than 4 Antennas (cont.)
July 2010
Cyclic Shift for More Than 4 Antennas (cont.)
Number of TX chain
CSD1
CSD2
CSD3
CSD4
CSD5
CSD6
CSD7 7
0ns
-25ns
-50ns
-75ns
-100ns
-125ns
-150ns
-200ns
-175ns
For number of TX chain =7:
Yung-Szu Tu, et al., Ralink Tech.

9. Cyclic Shift for More Than 4 Antennas (cont.)
July 2010
Cyclic Shift for More Than 4 Antennas (cont.)
For number of TX chain =8:
Number of TX chain
CSD1
CSD2
CSD3
CSD4
CSD5
CSD6
CSD7
CSD8 8
0ns
-25ns
-50ns
-75ns
-100ns
-125ns
-150ns
-175ns
-125s
-200ns
-100s
Yung-Szu Tu, et al., Ralink Tech.

10. Straw Poll on VHT-SIGA CSD
July 2010
Straw Poll on VHT-SIGA CSD
Do you support adding to the specification framework document (IEEE /0992)
3.2.x: The CSD (Cyclic Shift Diversity) values for up to 4 antennas in VHT-SIGA are the same as the CSD values for the non-HT portion of the packet defined in Table 20-8 of Std n-2009.
Yes:
No:
Abs:
Yung-Szu Tu, et al., Ralink Tech.

11. Straw Poll on CSD for More Than 4 Antennas
July 2010
Straw Poll on CSD for More Than 4 Antennas
For more than 4 antennas, do you support
1. To constrain the CSD values in L-STF, L-LTF, and L-SIG and VHT-SIGA to be within an interval of 200ns
2. CSD values are different for different antennas
3. VHT-SIGA has the same CSD values as L-STF, L-LTF, and L-SIG
Yes:
No:
Abs:
Yung-Szu Tu, et al., Ralink Tech.

12. July 2010
Reference
[1] Robert Stacey, et. al., Specification Framework for TGac, IEEE /0992r11, May 18, 2010
[2] IEEE, Std n-2009
[3] Tsuguhide Aoki and Daisuke Takeda, Backward Compatibility of CDD Preambles, IEEE /0006r1, Jan. 17, 2005
[4] Eldad Perahia and Robert Stacey, Next Generation Wireless LANs, Cambridge, 2008
Yung-Szu Tu, et al., Ralink Tech.