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Signaling for Adaptive Modulation in Wireless Networks

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Explore Dr. Günter Kleindl's research on improving throughput and range through adaptive modulation with signaling. Learn about implementing adaptive modulation, OFDM subcarriers, range enhancement, and more.

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Signaling for Adaptive Modulation in Wireless Networks

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  1. Signaling for Adaptive Modulation by Dr. Günter Kleindl Siemens AG G. Kleindl / Siemens

  2. Motivation and Requirements • Adaptive modulation is one method to improve the throughput and/or range • Adaptive modulation requires signaling • Easy implementation and compatibility to IEEE 802.11a/g G. Kleindl / Siemens

  3. SNR(f) QPSK 3/4 QPSK 1/2 BPSK 3/4 f Conventional Modulation for OFDM-Subcarriers 64 QAM 3/4 64 QAM 2/3 16 QAM 3/4 SNR 16 QAM 1/2 shifting of grid Average BPSK 1/2 • All subcarriers get the same modulation alphabet G. Kleindl / Siemens

  4. Adaptive Modulation for OFDM-Subcarriers SNR Average • Bundles of adjacent subcarriers • get individual modulation alphabets G. Kleindl / Siemens

  5. How to implement ? Source RTS Data CTS ACK Destination • A small extension in the RTS / CTS frames is a solution G. Kleindl / Siemens

  6. RTS Frame Format Frame Control Duration RA TA FCS Protocol Version Type Subtype Other Bits • Take an unused bit combination in the Subtype field • to signal in the RTS that a terminal is able to transmit • according to the bit loading feature, • e.g. Subtype = 0011 G. Kleindl / Siemens

  7. CTS Frame Format Frame Control Duration RA Bit Loading Table FCS • The destination terminal measures the RTS • subcarriers and answers with a bit loading table for • adaptive modulation in the CTS frame. • The source modulates the data frame according to • the bit loading table. G. Kleindl / Siemens

  8. 000 Nil 001 BPSK 010 QPSK 011 8 PSK 100 16 QAM 101 32 QAM 110 64 QAM 111 128 QAM Example of a Bit Loading Table • Number 8 possible PHY-modes and select one for • each of the 16 bundles, i.e. 3 bit x 16 = 48 bits = 6 bytes. • Transport these bytes in the CTS frame. G. Kleindl / Siemens

  9. Range Enhancement • Adaptive modulation can significantly improve • the range G. Kleindl / Siemens

  10. Other Company’s ResultsDoc.#: 11-02-232r0-WNG from Aware • Adaptive modulation can significantly improve • the throughput G. Kleindl / Siemens

  11. Conclusions • Adaptive modulation is one method to improve the throughput and/or range • The available RTS/CTS signaling can easily be extended • for adaptive modulation and further techniques like • multiple transmit antennas G. Kleindl / Siemens

  12. Thank you foryour attention ! G. Kleindl / Siemens

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