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Published byCecelia Starley Modified over 4 years ago

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**Cyclic Shift Diversity Design for IEEE 802.11aj (45GHz)**

Date: Presenter: Shiwen HE Authors/contributors:

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Background Cyclic shift diversity (CSD) is a simple and valid strategy that can be used to achieve spatial diversity. CSD can reduce the effects of unintended beamforming when correlated signals are transmitted in multiple space-time streams. CSD can be achieved straightforwardly by introducing different cyclic shifts to every part of the OFDM symbols or blocks in SC systems. 802.11n and ac defined their CSD table values respectively. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**Introduction In OFDM scenario:**

- Cyclic delays are introduced to the effective parts of the OFDM symbols, illustrated as following. In SC scenario: - Cyclic delays are introduced to the parts of the blocks, illustrated as following. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**The Optimization of CSD values ： **

- When applying cyclic delay, the signal received via multiple transmitting antennas in frequency domain is where is the cyclic delay value at the transmitter antenna，and is the number of transmitter antenna, is the addictive noise. - The cyclic delays can be seen respectively as phase rotations introduced to the channel frequency response Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**is a random gap of frequency. **

- It is assumed that the composite channels have similarly stochastic properties, expressed by a common correlation function is a random gap of frequency. - Then the correlation function of the composite channels can be expressed as Since then which implies that the correlation is reduced. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**where F is the sub-carrier spacing, and l, m are integer variables. **

- With selecting appropriately , it is possible to force a zero in the correlation function and to introduce better diversity to the composite channel. where F is the sub-carrier spacing, and l, m are integer variables. - Such a result is achieved for delays Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**Four sub-channels realization of 4x1 system(OFDM):**

Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**Equivalent channel realization of 4x1 system(OFDM):**

Without CSD Applying CSD Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**TCS(n) values for the data fields of a PPDU**

CSD Table for OFDM Data field : TCS(n) values for the data fields of a PPDU NSTS,total Cyclic shift for space-time stream n (ns) 1 2 3 4 - -128Ts -170Ts -85Ts -64Ts -192Ts Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**CSD cont: Spatial Extending for OFDM :**

NSTS NTx Qk 1 2 4 3 Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**TCS(n) values for the data fields of a PPDU**

CSD Table for SC Data field : TCS(n) values for the data fields of a PPDU NSTS,total Cyclic shift for space-time stream n (ns) 1 2 3 4 - -128Tc -170Tc -85Tc -64Tc -192Tc Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**CSD cont: Spatial Extending for SC :**

NSTS NTx Qk 1 2 4 3 Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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Simulation Comparisons of error performance of the 2x1 OFDM system with QPSK Modulation and 1/2-rate. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**Comparisons of error performance of the 2x1 SC system with QPSK **

Modulation and 1/2-rate. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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Conclusion With QPSK modulation and 1/2-rate, PER performance can be improved about 1dB at the PER of 0.1 by using the proposed CSD table values . Compared with STBC, the proposed CSD scheme loses a little gain with QPSK modulation and 1/2-rate. However, CSD scheme has low additional complexity. The proposed CSD table values can be applied to the data field of the OFDM or SC scenario. Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**References [1] 11-06-0952-01-000n-lb84-csd-text-proposal-submission.**

[2] ac-legacy-csd-table-for-11ac. [3] K. Witrisal, Y.-H. Kim and R. Prasad, “Antenna diversity for OFDM using cyclic delays”, Benelux: Roc. SCVT-2001, , pp Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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**Thanks for Your Attention.**

Agilent technologies E8267D PSG Vector Signal Generator, up to 44GHz, 160 MHz (extendable to 2 GHz) RF modulation bandwidth E4448A PSA Spectrum Analyzer, 3 Hz - 50 GHz, Analysis Bandwidth 10 MHz analysis bandwidth (option B7J for the Basic mode) Optional 40 or 80 MHz analysis bandwidth to capture and measure complex signals. View the demo -78 dB (nominal) third order intermodulation for 40 or 80 MHz analysis bandwidth Up to 300 MHz analysis bandwidth for calibrated VSA measurements Rohde&Schwarz (R&S)

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