1. Rotation Modulation Application to 802.11ac system
January 2010
doc.: IEEE /0084r3
Rotation Modulation Application to ac system
Date:
Authors:
Brian Hart, Cisco Systems

2. Abstract
Rotation modulation technique for QPSK has already been adopted in ad system. Based on our recent research, this technique can also improve the overall performance of ac system.

3. Our Proposed Scheme
Encode
Rotational Mod.
OFDM
Space-Time-Freq Interleaver
( I/Q Separate)
Precoding
OFDM
Encode
Rotational Mod.
CSI Estimation
1 Introduce rotational modulation matrices for 4/16/64/256 QAM
2 Introduce space/time/frequency I/Q separate interleaver

4. Our Proposed Rotation Matrix to 802.11ac system
Modulation
Proposed Rotation Matrix
QPSK
16QAM
64QAM
256QAM

5. Simulation Parameters
Values
PHY scheme
OFDM
Antenna scheme
2*2 ,4*4,8*8
Length of FFT 64
Number of subcarriers 57
Code Type
LDPC, CC
Code Rate
3/4, 5/6
Modulation Type
QPSK 16QAM 64QAM 256QAM
Channel Type
TGac Channel Model E LOS,NLOS[4,5]

6. Rotation Modulation LOS (2*2),LDPC

7. Gain of Rotation Modulation (LOS2*2),LDPC
MCS
MODULATION
CODE RATE
GAIN (dB) (FER=0.01) 2
QPSK
3/4
7.2 4
16-QAM
4.8 7
64-QAM
5/6
4.5 8
256-QAM
1.8

8. Rotation Modulation LOS (2*2),CC

9. Gain of Rotation Modulation (LOS2*2),CC
MCS
MODULATION
CODE RATE
GAIN (dB) (FER=0.01) 2
QPSK
3/4
7.4 4
16-QAM
5.6 7
64-QAM
5/6
5.2 8
256-QAM
2.3

10. Rotation Modulation NLOS(4*4) ,CC

11. Gain of Rotation Modulation (NLOS4*4),CC
MCS
MODULATION
CODE RATE
GAIN (dB) (FER=0.01) 2
QPSK
3/4
5.2 4
16-QAM
4.4 7
64-QAM
5/6
4.1 8
256-QAM
1.5

12. Rotation Modulation NLOS(8*8) ,CC

13. Gain of Rotation Modulation (NLOS8*8),CC
MCS
MODULATION
CODE RATE
GAIN (dB) (FER=0.01) 2
QPSK
3/4
3.2 4
16-QAM
2.8 7
64-QAM
5/6
3.3 8
256-QAM
1.5

14. Effect of phase noise 2.2 2.3 2.4 2.6 MCS2 Gain（db）（FER=0.01）
No PN(Ideal)
2.2
With PN(Ideal)
2.3
No PN(LS)
2.4
With PN(LS)
2.6

15. June 2010
doc.: IEEE /xxxxr0
Conclusions
No matter LOS or NLOS channel, No matter LDPC Coding or Convolutional Coding, rotational modulation has obvious performance gain over conventional modulations, which is up to 7 dB.
For different antenna schemes,2*2 antenna scheme can achieve the largest relative gain; for 4 * 4 and 8 * 8, it also can obtain remarkable gain.
Rotational modulation is robust for phase noise.
In a word, based on our proposal, rotation modulation is also applicable to ac system.
Brian Hart, Cisco Systems

16. References
1. IEEE P Wireless LANs PHY/MAC Complete Proposal Specification,
2. 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
3. Wu Zhanji, A novel Coding-Rotated-Modulation OFDM scheme, International Conference on Communication Technology and Application 2009, ICCTA 2009, October, 2009, pp:
Erceg, V. et al. “TGn Channel Models.” Doc. IEEE /940r4.
Breit, G. et al., “TGac Channel Model Addendum,” Doc. IEEE /0308r12