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Joint Coding and Modulation Diversity for the Next Generation WLAN

Joint Coding and Modulation Diversity for the Next Generation WLAN. Date: 2013-01-15. Authors:. Abstract. The combination of OFDM and MIMO is still a key feature for high-throughput transmission in the next generation WLAN.

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Joint Coding and Modulation Diversity for the Next Generation WLAN

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  1. Joint Coding and Modulation Diversity for the Next Generation WLAN Date: 2013-01-15 Authors:

  2. Abstract • The combination of OFDM and MIMO is still a key feature for high-throughput transmission in the next generation WLAN. • An improved MIMO-OFDM scheme based on modulation diversity named Joint Coding and Modulation Diversity (JCMD) is proposed. It can take full advantage of the coding-gain, the frequency diversity of OFDM system and the spatial diversity of MIMO all together. Simulation results turn out that it can obtain obvious SNR gain as compared with the current BICM-MIMO scheme, which is up to 7dB.

  3. Background • IEEE 802.11ac greatly enhanced the air interface key technologies, such as enhanced LDPC coding and tone mapper, multiuser (MU) MIMO, broader bandwidth up to 160MHz, higher order quadrature amplitude modulation (QAM) modulation up to 256QAM and more transmit antenna number up to 8. • [1] had proposed that the system capacity of 10 G bit/s will be achieved by combining some possible technologies for the next generation WLAN. • The system capacity should be improved to maintain high performance. • Higher peak data rate • extend the bandwidth/channel, e.g. 320 MHz/ch • The next generation WLAN will support more spatial streams • support more users in a MU-MIMO transmission • Higher spectrum efficiency • DL-OFDMA • Advanced SDMA

  4. JCMD-MU-MIMO Transmit Diagram • NOTES • The blocks drawn in dotted line are our proposed additional processing on the basis of the current 802.11 ac standard scheme. • In simulations, the spatial mapping method for SU and MU MIMO are SVD and BD precoding, respectively.

  5. Joint Coding and Modulation Diversity • Rotational Modulation • Maximized modulation diversity order. • The relationship between conventional modulated complex symbol A + j*B and the rotational modulated complex symbol X + j*Y can be expressed as: QPSK R-QPSK L=1 L=2

  6. Proposed Rotational Matrices Optimum rotational matrices are proposed as follows

  7. Joint Coding and Modulation Diversity • Q-Component Interleaver • Spatial Q-Interleaving Let and denote the input Q-component and the output Q-component of the spatial Q-interleaver on the spatial stream at the t instant. The spatial Q-interleaving is defined as follows, where is the spatial stream number. (1) • Frequency domain Q-Interleaving On each spatial stream, the frequency domain Q-Interleaving is carried out as follows, where is the OFDM subcarrier number. (2)

  8. Simulation Parameters for 802.11ac SU-MIMO Scheme

  9. FER performance for 2*2 SU-MIMO scheme in 802.11 AC Channel, case E, NLOS

  10. FER performance for 4*4 SU-MIMO scheme in 802.11 AC Channel, case E, NLOS

  11. Simulation Parameters for 802.11ac MU-MIMO Scheme

  12. FER performance for MU-MIMO scheme in 802.11 AC Channel, case E, NLOS, 2 users, each user has 2 spatial streams.

  13. Hardware prototype system

  14. FER performance for Hardware prototype system in VA channel • Hardware prototype system has significant performance advantage about 3 dB.

  15. Complexity Analysis • The total number of addition/subtraction and multiplication/division operations is used to represent the overall complexity base on the hardware prototype system. The overall complexity of the proposed JCMD scheme is almost the same as the conventional BICM scheme.

  16. Conclusions • JCMD scheme jointly optimizes the MIMO-OFDM, channel coding and modulation together, which makes full use of time, frequency and space diversity. • Rotational modulation • Q-components interleaver • The proposed scheme can obtain obvious SNR gain (up to 7dB) as compared with the current BICM MIMO scheme in IEEE 802.11 standard for LDPC/BCC coding, all MCSs and various channels . • Significant SNR gain • Larger coverage area • Lower transmit power • Low complexity • Low processing power and cost • JCMD is suitable for the next generation WLAN.

  17. References [1] 11-12-0820-00-0wng-improved-spectrum-efficiency-for-the-next-generation-wlans.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

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