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Outline of Draft Standard for 5 GHz

This draft standard outlines the parameters and modulation techniques for a 5 GHz OFDM system. It discusses the advantages of OFDM, sub-carrier allocation, base band modulation, channelization, header parameters, training symbols, encoder, and other functions.

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Outline of Draft Standard for 5 GHz

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  1. Outline of Draft Standard for 5 GHz Hitoshi Takanashi, Masahiro Morikura, Richard van Nee Lucent + NTT Hitoshi, Masahiro, Richard Lucent+NTT

  2. Advantages of OFDM • Robust against delay spread • No feed back loop : stable • Any modulation schemes can be applied to the base band modulation. Same spectrum shape is found. • Fall back function is supported • Same PHY as BRAN’s would be possible Hitoshi, Masahiro, Richard Lucent+NTT

  3. Configuration of PHY Modulation in Base band Hitoshi, Masahiro, Richard Lucent+NTT

  4. OFDM Parameters • 48 sub-carriers in 12.5 MHz • Center carrier is not used • 64 points of FFT/IFFT • Base band modulation : • DPSK, DQPSK and 16QAM • 5 carriers in 100 MHz (15 MHz separation) Hitoshi, Masahiro, Richard Lucent+NTT

  5. Sub-carrier Allocation The center carrier interfered by the DC offset is not used. Hitoshi, Masahiro, Richard Lucent+NTT

  6. Base band Modulation • DBPSK and DQPSK • Differential coding for differential detection • DBPSK, r=1/2 : 5 Mbit/s • DQPSK, r=1/2 : 10 Mbit/s • DQPSK, r=3/4 : 15 Mbit/s • Pilot carriers (#3, 26 and 47) • 16 QAM • Pilot carriers (#3, 26 and 47) • r=1/2 : 20 Mbit/s • r=3/4 : 30 Mbit/s Hitoshi, Masahiro, Richard Lucent+NTT

  7. Channelization in L & M band • 10 carriers in 200 MHz band • Guard band : 13.875 MHz to the band edge • 15 MHz separation Hitoshi, Masahiro, Richard Lucent+NTT

  8. Channelization in Upper band • Same as lower / middle band Hitoshi, Masahiro, Richard Lucent+NTT

  9. Header Parameters • Long Guard Interval is secured Hitoshi, Masahiro, Richard Lucent+NTT

  10. Ts=T+TG Tprefix T Tpostfix  T Cyclic Extention • A raised cosine window to reduce out band power (roll off factor : 0.025) Hitoshi, Masahiro, Richard Lucent+NTT

  11. Training Symbols • Short and Long symbols Hitoshi, Masahiro, Richard Lucent+NTT

  12. Encoder • 64 states convolutional encoder • rate : 1/2 - 3/4 (punctured) Hitoshi, Masahiro, Richard Lucent+NTT

  13. Bit stealing/insertion Hitoshi, Masahiro, Richard Lucent+NTT

  14. Layer Reference Model • As used in the current MAC • New Primitive parameters are defined Hitoshi, Masahiro, Richard Lucent+NTT

  15. PLCP Frame Format Hitoshi, Masahiro, Richard Lucent+NTT

  16. Other Functions • Bit stuff to make the MPDU length multiples of an OFDM symbol. • Tail bits to set the convolutional encoder to a state. • Scrambler to minimize the data DC offset. • Interleave to enhance error correction function (within an OFDM symbol) Hitoshi, Masahiro, Richard Lucent+NTT

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