1. Further Rotation Modulation Application
January 2010
doc.: IEEE /0084r3
Further Rotation Modulation Application
Date:
Authors:
Brian Hart, Cisco Systems

2. Abstract
According to the IEEE /0433r2 document, the rotation modulation technique has already been adopted in QPSK modulation.
Based on our recent research, this technique can also improve the performance of 16QAM and 64QAM modulations. Therefore, we recommend to introduce this scheme for 16QAM and 64QAM.

3. Rotation modulation
IEEE /0433r2 document has adopted rotation modulation technique in QPSK modulation.
The process of rotation modulation is
The rotation matrix for QPSK is

4. Our Proposed Rotation Matrix
However, based on our research, the rotated 16QAM and 64QAM modulations also exhibits obvious SNR gain as well.
Modulation
Proposed Rotation Matrix
16QAM
64QAM

5. Simulation Parameters
Values
PHY scheme
OFDM
Length of FFT
512
Number of subcarriers
355
Code Type
LDPC in Draft 0.1
Code Rate
1/2, 3/4, 5/8, 13/16
Modulation Type
QPSK, 16QAM, 64QAM
Channel Type
Conference Room STA-STA [2]

6. Rotation Modulation NLOS R=1/2 & 5/8
Slide 6

7. Rotation Modulation NLOS R= 3/4 & 13/16

8. Gain of Rotation Modulation (NLOS)
Gain (FER=0.01)
QPSK
16QAM
64QAM
13/16
1.5
1.0
0.8
3/4
0.9
0.6
0.5
5/8
0.3
0.2
1/2

9. Rotation Modulation LOS R=13/16
For LOS channel, rotation modulation still exhibits better performance.

10. Conclusions
For NLOS-OFDM system, rotation modulation has obvious performance gain over conventional modulations, especially for high code rates.
The gain of rotated 16QAM is up to 1.0 dB
The gain of rotated 64QAM is up to 0.8 dB
For LOS-OFDM system, the rotation modulation still exhibits better performance.
In a word, rotation modulation is applicable to 16QAM and 64QAM.

11. Comment-1 Change to 21.5.3.2.3.3 16-QAM Modulation
Add the following sentences at the end of :
Each pair of constellation points
is converted into
where the matrix
and the indices P(k), in the range NSD /2 to NSD-1, are as defined in
The output is the stream of blocks

12. Comment-2 Change to 21.5.3.2.3.4 64-QAM Modulation
Add the following sentences at the end of :
Each pair of constellation points
is converted into
where the matrix
and the indices P(k), in the range NSD /2 to NSD-1, are as defined in
The output is the stream of blocks

13. References
1. IEEE P Wireless LANs PHY/MAC Complete Proposal Specification,
2. IEEE P Wireless Channel Models for 60 GHz WLAN Systems,
3. J.Boutros, E.Viterbo, Signal Space Diversity: a power and bandwidth efficient diversity technique for the Rayleigh fading channel. IEEE Trans. Inform.Theory, vol.44. pp , July
4. Wu Zhanji, A novel Coding-Rotated-Modulation OFDM scheme, International Conference on Communication Technology and Application 2009, ICCTA 2009, October, 2009, pp: