Presentation on theme: "Doc.: IEEE 802.11-10/1052r0 Submission September 2010 Richard van Nee, QualcommSlide 1 VHT-SIG-A and VHT-SIG-B Field Structure Date: 2010-09-09 Authors:"— Presentation transcript:
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 1 VHT-SIG-A and VHT-SIG-B Field Structure Date: Authors:
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 2 Introduction Fields for VHT-SIG-A and VHT-SIG-B were accepted in the 11ac spec framework 992r13 This presentation defines the order of these fields and some bit widths that were not fixed yet in 992r13
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 3 VHT-SIG-A/B Structure For ease of parsing, the common fields between SU and MU are scheduled first All fields are transmitted LSB first, like in 11n Fields are transmitted in order listed in the following tables with top of table transmitted first in time
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 4 Notes on Field Changes Group ID of all ones (instead of all zeros) signals SU/Broadcast/Multicast –Prevents large peak-to-average power ratio in VHT-SIG-A –With all zeros Group ID, there would be 21 zeros and just 3 ones in VHT- SIG-A1 for a 20 MHz single stream Broadcast/Multicast packet with no STBC SU Beamforming bit added in VHT-SIG-A –MU beamforming is signaled through Group ID –Notice that TGac voted to not have a smoothing bit in large part due to the complexity in in determining when the bit should be set –However, it is still useful to provide the receiver basic information that the SU transmitted waveform is beamformed –Therefore this bit is set simply if a beamforming steering matrix is applied to the waveform in an SU transmission
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 5 VHT-SIG-A1 Fields and Order Bit Index FieldBit allocation Description 0-1BW2Set to 0 for 20 MHz, 1 for 40 MHz, 2 for 80 MHz, 3 for 160 MHz and MHz mode 2Reserved1Reserved for possible expansion of BW field. Set to 1. 3STBC1Set to 1 if all streams use STBC, otherwise set to 0. When STBC bit is 1, an odd number of space time streams per user is not allowed. 4-9Group ID [10/0582r1] 6A value of all ones indicates [10/0382r2]: -A single user transmission -A transmission where the group membership has not yet been established -A transmission that needs to bypass a group (e.g. broadcast) 10-21N STS [10/0582r1] 12For MU: 3 bits/user with maximum of 4 users Set to 0 for 0 space time streams Set to 1 for 1 space time stream Set to 2 for 2 space time streams Set to 3 for 3 space time streams Set to 4 for 4 space time streams Otherwise: first 3 bits contain stream allocation, set to 0 for 1 space time stream, set to 1 for 2 space time streams, etcetera up to 8 streams. Remaining 9 bits contain partial AID: being the 9 LSB bits of AID. For Broadcast and multicast, these 9 bits are set to 0. For STA-to-AP, these 9 bits are set to a special value (TBD) Reserved2All ones Total24 * Text in red indicates changes/additions relative to 992r13
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 6 VHT-SIG-A2 Fields and Order Bit Index FieldBit allocation Description 0-1Short GI2Set B0 to 0 for Long GI, set to 1 for Short GI Set B1 to 1 when Short GI and N sym %10 == 9 2-3Coding2Set B2 to 0 for BCC, set to 1 for LDPC B3 purpose is under discussion 4-7MCS4For SU/Broadcast/Multicast: MCS index For MU: Reserved, set to all ones 8SU- Beamformed 1Set to 1 when packet is a SU-beamformed packet Set to 0 otherwise For MU: Reserved, set to 1 9Reserved1All ones 10-17CRC8CRC calculated as in 11n Section with C7 in B Tail6All zeros Total24
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 7 VHT-SIG-B Fields and Order Order of transmission: Length, MCS (in case of MU) / Reserved (in case of SU), Tail Fields are transmitted LSB first FieldMU bit allocationSU bit allocationDescription 20 MHz40 MHz80 MHz20 MHz40 MHz80 MHz Length length of useful data in PSDU in units of 4 octets MCS Reserved All ones Tail All zeros Total # bits
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 8 Bit Allocation of CRC in SERVICE Field CRC of VHT-SIG-B bits excluding tail bits is calculated as in 11n Section As in 11n, C7 is transmitted first. So C7 is mapped to B8 of the SERVICE field, C6 is mapped to B9, …, C0 is mapped to B15 of the SERVICE field.
doc.: IEEE /1052r0 Submission September 2010 Richard van Nee, QualcommSlide 9 Straw Poll Do you support adding the VHT-SIG-A/B and VHT- SIG-B CRC structure from slides 3-8 to the specification framework document, 11-09/0992?