Changes between Version 7 and Version 8 of OFDM/MIMO/Docs/PHYDetails/FrameFormat
- Timestamp:
- Aug 29, 2009, 9:16:11 PM (15 years ago)
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OFDM/MIMO/Docs/PHYDetails/FrameFormat
v7 v8 7 7 8 8 [[Image(OFDM/MIMO/Docs/Images:FrameFormatOverview.png)]] 9 10 The actual format depends on the antenna mode: 11 12 '''SISO Frame Format'''[[BR]] 13 [[Image(OFDM/MIMO/Docs/Images:SISO_Frame_Format.png, 684)]] 14 15 '''Alamouti Frame Format'''[[BR]] 16 [[Image(OFDM/MIMO/Docs/Images:SISO_Frame_Format.png, 684)]] 17 18 '''Multiplexing Frame Format'''[[BR]] 19 [[Image(OFDM/MIMO/Docs/Images:MIMO_Frame_Format.png)]] 9 20 10 21 === Preamble === … … 34 45 The number of full-rate symbols is calculated automatically by the transmitter based on the modulation rate and packet length specified by user code. The maximum number of full-rate symbols is 2047 (way more than enough for very long packets). 35 46 36 == SISO Frame Format == 47 The number of full-rate symbols can be zero. This enables header-only packets. User code selects this mode by transmitting a packet whose length equals the number header bytes specified during the OFDM core initialization. 37 48 38 [[Image(OFDM/MIMO/Docs/Images:SISO_Frame_Format.png, 684)]] 49 == Checksums == 50 The OFDM transmitter subsystem includes a checksum calculation and insertion block. This block will overwrite the last two bytes of the header with a 16-bit CRC calculated over the full contents of the base-rate symbols. The checksum block will overwrite the last four bytes of the packet with a 32-bit CRC calculated over the full packet, including the header. The 32-bit full-packet checksum is not used for header-only packets. 39 51 40 == Multiplexing Frame Format == 41 42 [[Image(OFDM/MIMO/Docs/Images:MIMO_Frame_Format.png)]] 52 User code must accommodate these checksum insertions by leaving the corresponding bytes empty in packets loaded for transmission, and by ignoring these bytes when processing received packets.