1. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Joint Coding and Modulation Diversity for 802.11ah Date: 2011-11-05 Authors: Slide1

2. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission 802.11ah shall include support for 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz PHY transmissions. [1] An 802.11ah STA shall support reception of 1 MHz and 2 MHz PHY transmissions. [1] The 2 MHz PHY transmission shall be an OFDM based waveform consisting of a total of 64 tones (including tones allocated as pilot, guard and DC). This implies a tone spacing of 31.25 kHz. The tone spacing for all other bandwidths PHY transmissions shall be same as the tone spacing in the 2 MHz PHY transmission. Compared with 802.11ac, Tgah has smaller bandwidth and tone spacing. Background Slide2

3. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Based on IEEE 802.11-11/0883r1 [2] TGah outdoor channel model 3GPP/3GPP2 SCM (spatial channel model) shall be used to evaluate 11ah outdoor MIMO link and system performance. TGah indoor channel model The proposed indoor channel model for TGah is based on the 802.11n channel models, which have been widely used in the 802.11 Standard development. 802.11ah Channel Model Slide3

4. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Abstract Doc.IEEE802.11-11/0069r0 [3] proposed to use TGac features as a basis for Tgah. Doc. IEEE 802.11-10/0336r0 [4] has demonstrated the performance advantages of Joint Coding and Modulation Diversity technique in 802.11 ac system. Based on our recent research, Joint Coding and Modulation Diversity technique can also improve the overall performance of 802.11ah system, especially in MIMO-OFDM scenario. Therefore, we recommend to introduce this technique to 802.11ah system. Slide 4

5. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Proposed Transmitter/Receiver Block Diagram NOTES — Red blocks are our proposed amendment. —The number of transmit chains can be not equal to the number of space-time streams — SVD-precoding, codebook-percoding and non-precoding are all supported. Slide 5

6. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission In the amendment, we use rotational modulation method to combine with time diversity of channel coding, spatial diversity of MIMO and frequency diversity of OFDM, which is named joint coding and modulation diversity (JCMD). As compared with JCMD, the processing scheme in IEEE 802.11n/ac Standard is named bit interleaved coded modulation (BICM) for simplicity. Amendment and simulation are based on the document IEEE 802.11n-2009,IEEE 802.11-09/0992r18 and Draft 802.11ac D1.1. Slide 6

7. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission According to rotational matrix ， rotate the conventional modulated symbol. The relationship between conventional modulated complex symbol A + j*B and the rotational modulated complex symbol X + j*Y is shown in equation: where A and B are the I (in-phase) and Q (quadrature) component of the normal QAM, respectively; X and Y are the I and Q component of rotated QAM, respectively Basic principle of the rotational modulation Slide 7

8. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission It is already used in IEEE 802.11ad. An example of rotated QPSK Slide8

9. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Our Proposed Rotation Matrix to 802.11ah system Modulation Proposed Rotation Matrix QPSK 16QAM 64QAM 256QAM Slide 9

10. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of the Spatial Interleaving In this process, denotes rotated symbol on the stream at time sample. So the interleaving is usual spiral layer interleaving process among all streams at the same time. The method is as follow: Where is the number of spatial streams. For example, consider the case, =4: Corresponding, uses the inverse algorithm at the receiver as follow: Slide 10

11. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of the Spatial Q-Interleaving In the spatial Q-interleaving process, I components of the complex signals are unchanged, while Q components of signals are changed as follows: That is to say, Q component on stream i will be moved to the stream (Nss-i-1). So, it is just a simple reverse interleaver, and the interleaver length is the number of the spatial streams. Slide 11

12. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of the Frequency domain Q- interleaveing In the frequency domain Q-interleaving process, the I components of the complex signals are unchanged, while Q components of signals are changed as follows: is the number of subcarriers for data. That is to say, Q component on subcarrier i will be moved to the subcarrier. So, it is just a simple cyclic-shift interleaver, and the linterleaver length is the number of data subcarriers. Slide 12

13. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of demodulation Due to spatial Q-interleaving and frequency Q-interleaving, fading coefficient of I component is usually different from that of Q component. Slide 13

14. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of demodulation For example, consider the R-QPSK （ rotational quadrature phase-shift keying ） : The procedure for demodulation is shown as follows: 1)Compute the distance between the received point and each reference constellation point. The relationship between the reference constellation point and the rotational constellation point is shown as follows: so Slide 14

15. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Basic principle of demodulation 2) Compute the Likelihood ratio (LLR) for every bit. The LLR is the input of the decoder. For the first bit : For the second bit: There is also a simplified algorithm to compute the LLRs: Similarly, for M-ary QAM(Quadrature amplitude modulation), we should compute LLRs for bits. Slide 15

16. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Simulation Parameters ParametersValues PHY schemeOFDM Antenna scheme2*2 Length of FFT64 Number of subcarriers56 Number of data subcarriers 52 Code TypeBCC Channel Model 802.11n channel models (Indoor) 3GPP SCM channel model (Outdoor) Code Rate3/4, 5/6 Modulation TypeQPSK 16QAM 64QAM Bandwidth2 MHz Sub-carrier spacing31.25 kHZ Channel estimationIdeal channel estimation Slide 16

17. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission MCS (modulation and coding scheme) （ 2*2 ） MCSMODULATIONCODE RATENumber of OFDM symbols per frame Block Size 2QPSK3/461248 416-QAM3/441668 764-QAM5/621248 Slide 17

18. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Indoor Channel Model LOS case E [2],BCC ParametersValue 2 2 2 Carrier Frequency0.8 GHz Code Rate3/4, 5/6 Modulation TypeQPSK,16QAM,64QAM Bandwidth2.0 MHz Sample Time500 ns FFT64 Subcarrier Bandwidth 31.25 kHz CP16 Speed1.2 km/h Gain dB (FER=0.1) QPSK6 16QAM5.6 64QAM5 Slide 18

19. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Outdoor Channel Model 3GPP SCM [3],BCC ParametersValue 2 2 2 Carrier Frequency0.8 GHz Code Rate3/4, 5/6 Modulation TypeQPSK,16QAM,64QAM Bandwidth2.0 MHz Sample Time500 ns FFT64 Subcarrier Bandwidth 31.25 kHz CP16 Speed1.2 km/h Gain dB (FER=0.1) QPSK8 16QAM7 64QAM6 Slide 19

20. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Hardware Platform The platform Rohde&Schwarz AMU (fading simulator) 2*FSV(signal analyzer) 2*SMBV(vector signal generator) 2*PicoChip PC203 Baseband Unit 2*RRU Slide 20

21. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Hardware Simulation Results SISO: JCMD obtains 2 dB SNR gain at FER=0.1 as compared with BICM. ParametersValue CodeTurbp Modulation Type QPSK Code Rate 3/4 Code Length 768 Channel Model TU 3Path Speed 0km/h Channel EstimationLS Slide 21

22. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Hardware Simulation Results 2*2 MIMO: JCMD obtains 3.3dB SNR gain at FER=0.1 as compared with BICM. ParametersValue Channel ModelVA_MIMO_60km/h Code3GPP LTE Turbo Code Rate3/4 Modulation TypeQPSK SchemeBICM/JCMD PrecodingNo-Precoding Channel EstimationLS, LMMSE MIMO detectionMMSE Slide 22

23. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Conclusions It is proved that the proposed scheme has the obvious SNR gains over the current scheme, which implies –Larger coverage area –Lower transmit power The proposed scheme is easy to be implemented –Rotated QAM modulation –Q-components Interleaver within one OFDM symbol In a word, the proposed scheme is very suitable for TGah to meet the requirement of PAR. Slide 23

24. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission References [ 1] 11-11-1294-00-00ah-spec-framework-text-of-11ah-bw-modes.pptx [2] 11-11-0883-01-00ah-Channel-Model-Text.docx [3] 3GPP TR 25.996 - Technical Specification Group Radio Access Network; Spatial channel model for Multiple Input Multiple Output (MIMO) simulations [4] 11-11-0069-01-00ah-tgah-Introductory-proposal.ppt [5] 11-11-0336-00-00ac-joint-coding-and-modulation-diversity-to-802- 11ac.ppt [6]11-11-1137-02-00ah-specification-framework-for-tgah.docx Slide 24

25. doc.: IEEE 802.11-11/1536r1 Zhanji Wu, et. Al. November 2011 Submission Strawpoll Do you accept JCMD as an enhanced coded modulation scheme to be considered for 802.11ah? -Yes -No -Abstain Slide 25