Non-Uniform Constellations for Higher Order QAMs in January 2015

Non-uniform constellations (NUCs) offer improved performance compared to uniform constellations (UCs) in the context of higher order QAMs discussed as potential technology for next-generation 60GHz OFDM. The use of NUCs optimizes the location of constellation points, ensuring robust and weak bits carry an optimal amount of information. Two-dimensional NUCs have shown higher gains compared to one-dimensional NUCs, albeit with a requirement for two-dimensional demapping. Examples of NUCs under different SNR conditions illustrate their effectiveness in maximizing channel capacity and information transmission.

• Non-Uniform Constellations
• Higher Order QAMs
• IEEE 802.11
• 60GHz OFDM
• Constellation Points

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1. January 2015 Non-Uniform Constellations for Higher Order QAMs Date: 2015/01/12 doc.: IEEE 802.11-15/0096r0 Authors: Name Daniel Schneider Affiliations Address Sony Deutschland GmbH Phone email Hedelfingestr. 61, 70327 Stuttgart, Germany daniel.schneider@eu.sony.com Submission Slide 1 Daniel Schneider, Sony

2. January 2015 doc.: IEEE 802.11-15/0096r0 Motivation (1/2) Higher order QAMs discussed in e.g. [1]-[2] as potential technology for next-generation 60GHz OFDM: 128-QAM, 256-QAM (up to 64-QAM in ad) SC: 64-QAM (up to 16-QAM in ad) Non-uniform constellations (NUCs) provide increased performance compared to uniform constellations (UCs) Optimum location of constellation points Robust and weak bits carry optimum amount of information Submission Slide 2 Daniel Schneider, Sony

3. January 2015 doc.: IEEE 802.11-15/0096r0 Motivation (2/2) Introduced lately in several broadcast standards DVB-NGH [3], DVB/S2x [4] Theoretical shaping gain up to 1.5dB Moderate complexity increase Change of QAM (de)mapper Submission Slide 3 Daniel Schneider, Sony

4. January 2015 doc.: IEEE 802.11-15/0096r0 NUC: 1-D vs 2D 1D 16NUC for 3dB 1-D NUC: 16-QAM 1-D NUC I/Q symmetry 1-D demapping as for uniform constellations (UC), i.e. same demapping complexity as for regular QAMs 1 0.5 Im{xl} 0 -0.5 -1 -1 -0.5 0 0.5 1 Re{xl} 2-D NUC: 16-QAM 2-D NUC Symmetric quadrants Higher gain compared to 1-D NUC 2-D demapping required Submission Slide 4 Daniel Schneider, Sony

5. January 2015 doc.: IEEE 802.11-15/0096r0 NUC Example for different SNR Conditions 8NUC for low SNR 8PSK reference 8NUC optimized at 0 dB 1 1 bitwise BICM capacity for AWGN channel 20 bitwise BICM capacity for AWGN channel 8NUC for SNR = 0 dB 2 over-lapping points robust bits robust bits 0.8 0.8 1 0.6 0.6 0.5 100 000 110 010 0.4 Im{xl} 0.4 0 weak bits bit 0 bit 1 bit 2 bit 0 bit 1 bit 2 weak bits 0.2 0.2 -0.5 111 101 001 011 0 0 -10 -5 0 5 10 15 -1 -10 -5 0 5 10 15 20 SNR [dB] SNR [dB] -1 -0.5 0 0.5 1 0.0000+0.4859+0.4859= 0.9719 Re{xl} 0.1282+0.3973+0.3973 = 0.9229 Interpretation: weak bits carry no information, 2 most robust bits with maximum distance 8NUC for high SNR 8PAM reference 8ary hexagonal lattice 1 1 bitwise BICM capacity for AWGN channel bitwise BICM capacity for AWGN channel robust bits robust bits 0.8 8ary ideal hexagonal lattice 0.8 1.5 0.6 110 0.6 1 weak bits 001 0.5 0.4 0.4 000 Im{xl} 100 0 weak bits bit 0 bit 1 bit 2 bit 0 bit 1 bit 2 011 0.2 0.2 -0.5 101 010 0 -1 -10 -5 0 5 10 15 20 0 111 -10 -5 0 5 10 15 20 SNR [dB] -1.5 SNR [dB] 0.9393+0.9697+0.9697 =2.8787 -1 0 1 0.9749+0.9749+0.9779 =2.9276 Re{xl} Submission Slide 5 Eisuke Sakai, Sony Corporation Interpretation: hexagonal lattice = dense packing , maximize minimum Euclidean distance

6. January 2015 doc.: IEEE 802.11-15/0096r0 Initial Simulations: Parameters Replacement of original uniform constellations by NUC OFDM, MCSs: 18-24 Additionally: 128- and 256-QAM Message Length: 1000bytes Channel AWGN AWGN (channel is very close to AWGN in the LOS case) Gain evaluated compared to UC at FER=10-2 1D and 2D NUC MCS index modulation bit/symbol 18 16-QAM 19 16-QAM 20 16-QAM 21 16-QAM 22 64-QAM 23 64-QAM 24 64-QAM 128-QAM 128-QAM 128-QAM 128-QAM 256-QAM 256-QAM 256-QAM 256-QAM coderate 1/2 5/8 3/4 13/16 5/8 3/4 13/16 1/2 5/8 3/4 13/16 1/2 5/8 3/4 13/16 4 4 4 4 6 6 6 7 7 7 7 8 8 8 8 Submission Slide 6 Daniel Schneider, Sony

7. January 2015 doc.: IEEE 802.11-15/0096r0 Initial Simulations: Results Channel: AWGN Up to 0.8dB gain of NUC compared to regular QAM gain compared to UC, OFDM AD, AWGN 1.2 1D NUC 2D NUC waterfall SNR gain [dB] @FER=1e-2 1 128-QAM* 256-QAM 802.11ad 0.8 64-QAM 0.6 0.4 16-QAM 0.2 0 1/2 5/8 3/4 13/16 5/8 3/4 13/16 1/2 5/8 3/4 13/16 1/2 5/8 3/4 13/16 code rate Slide 7 * Only 2D-NUC simulated Submission Daniel Schneider, Sony

8. January 2015 doc.: IEEE 802.11-15/0096r0 Conclusions Significant gain of NUC compared to UC Gain up to 0.8dB for 128-QAM and 0.7dB for 256-QAM Moderate complexity increase Isolated change of QAM mapper and demapper Same demapper complexity as for uniform constellations for 1-D NUCs 2-D demapping required for 2-D NUCs Submission Slide 8 Daniel Schneider, Sony

9. January 2015 doc.: IEEE 802.11-15/0096r0 References 1. Alecsander Eitan, Qualcomm, 11-14-1378-00-ng60 PHY rate for NG60 2. Alecsander Eitan, Qualcomm et al, 11-14-0652-00- 0wng-wng Next Generation 802.11ad 3. Next Generation broadcasting system to Handheld, physical layer specification (DVB-NGH), DVB BlueBook A160, 2012 4. DVB-S2X BlueBook A83-2 / EN302307-2 Submission Slide 9 Daniel Schneider, Sony

10. January 2015 doc.: IEEE 802.11-15/0096r0 BACKUP Submission Slide 10 Daniel Schneider, Sony