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Signaling for Adaptive Modulation in Wireless Networks

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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