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TGaf comments on PHY. Authors:. Date: 2011-03-15. Abstract.
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TGaf comments on PHY Authors: Date: 2011-03-15
Abstract Presentation addresses CID #14, #18, #19, #80, #81, #235, #239, #240, #478, #479, #480, #482, #629, #649, #652, #681, #733, #739, #748, #753, #754, #806, #832, #884, #973, #1005, #1197, #1198, #1199, #1202, #1286, #1287, #1292, #1293, #1297, #1301, #1302, #242, #279, #477, #586, #630, #632, #651, #674, #680, #739, #807, #830, #831, #832, #932, #1137, #1140, #1192, #1285
HT PHY in TVWS (as in 11af D1.0) • Half clocked operation of the HT PHY • Channel BW = 10 MHz • Up to 4 streams • 8us symbol • Quarter clocked operation of the HT PHY • Channel BW = 5 MHz • Up to 4 streams • 16 us symbol
HT PHY in TVWS (as in 11af D1.0) • Slot time: • 10 MHz: 13 us • 5 MHz: 21 us. • aSIFSTime • 10 MHz: 32 us • 5 MHz: 64 us • aCCATime • 10MHz: <8 us • 5 MHz: <16 us • Different symbol duration affects medium access
Issues of 11af D1.0 PHY • Multiple Options of symbol durations: • Additional auto detection mechanism required. • Hybrid mode (5-in-10) implementation more complex. • Multiple choices of timing parameters, making hybrid mode (5-in-10) operation unclear.
Alternative HT PHY in TVWS (1) • Quarter clocked operation of the HT 40/20Mhz PHY for 10 and 5 MHz operation • May allow ¼ down clocked legacy 11a PHY as 5MHz also. • Slot duration, IFS, CCATime etc may always follow the quarter clocked definition (4x longer than 11n). • No dynamic timing parameters.
Alternative HT PHY in TVWS (2) • If 20/40Mhz mode desired: • Quarter clocked VHT PHY (80/160) (single symbol duration).
Alternative HT PHY in TVWS (3) • DSSS rates (802.11b-DBPSK/DQPSK) tremendously enhances the range from OFDM PHY (by ~10dB without considering its PA advantage). • Beneficial for TVWS to enhance the coverage. • Low power, low complexity, low PAPR, easy to implement. • Propose to allow ¼ downclocked DSSS rates in all TVWS bands.
Conclusion • It is desirable to have the same symbol duration for 5 and 10 MHz channel bandwidth • Quarter clocked operation of 11n: • Symbol duration: 14.4/16us • Guard Interval: 1.6 / 3.2 us • Include quarter clocked DSSS rates of 11b to enhance TVWS coverage.
Straw Poll 1 • Do you support adoption of Quarter clocked 11n 20 and 40 MHz mode for TGaf for 5 and 10 MHz transmission to keep the same symbol duration and channel access parameters • Y • N • A
Straw Poll 2 • Do you support adoption of Quarter clocked 11b DSSS rates for TGaf? • Y • N • A
HT PHY in TVWS (as in 11af D1.0) • Spectral flatness • +/- 2 dB (1-16) • +2/-4 dB (17 – 28) • Spectral flatness requirement is not required by current receiver • TGac has adopted relaxed spectral flatness requirement • TGmb has adopted relaxed spectral flatness requirement
Modify Spectral Flatness requirement (CID #81) • Comments resolved • 81, 239, 240, 649, • Spectral flatness in TGaf 1.0 • +/- 2 dB (1-16) • +2/-4 dB (17 – 28) Change to • +/- 4 dB (inner carriers) • +4/-6 dB (outer carriers) • Spectral flatness requirement is not required by current receiver • TGac has adopted relaxed spectral flatness requirement • TGmb has adopted relaxed spectral flatness requirement
Straw Poll 3 • Do you support modifying the spectral flatness requirements for the inner carriers to +/- 4dB and outer carriers to +4 /-6 dB? • Y • N • A