January 2006 doc IEEE 802 11 051165 r

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Joint Proposal MAC Detail Date: 2006 -01 -17 Authors: Notice: This document has been prepared to assist IEEE 802. 11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802. 11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http: // ieee 802. org/guides/bylaws/sb-bylaws. pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard. " Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <stuart. kerry@philips. com> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802. 11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <patcom@ieee. org>. Submission 1 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 2 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 3 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 4 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 5 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 6 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 7 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 Submission doc. : IEEE 802. 11 -05/1165 r 5 8 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Abstract Æ This document presents the features of the TGn Joint Proposal MAC Specification Æ MAC Technical Specification is contained in Document: 11 -05 -1095/r 4 Submission 9 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MAC Features – as at November 2005 Submission 10 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Proposed MAC Features Submission 11 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MPDU Aggregation Æ Æ Robust Structure A-MPDU Aggregation is a purely-MAC function ■ ■ Æ Architecturally at the “Bottom of MAC” PHY has no knowledge of MPDU boundaries Control and data MPDUs can be aggregated Submission 12 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Basic A-MPDU Exchange Submission 13 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Value of A-MPDU Æ RTS/CTS/A-MPDU/BA sequence is typically 2. 5 x more efficient than Data/Ack Æ RTS/CTS/A-MPDU/BA is 30% more efficient than A-MSDU/Ack Æ Enables BA and Data to be aggregated (few % can be gained) Conditions: • Control rate 24 Mbps • Data rate 243 Mpbs • 500 B MSDUs Submission 14 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MSDU Æ Mechanism to provide enhanced efficiency at the top of the MAC layer Æ Mandatory feature of HT STA ■ Provides value to many, but not all types of flows outlined in the simulation scenarios Æ Maximum A-MSDU length • 3839 bytes (mandatory) • 7935 bytes (optional) ■ Submission Signaled in HT Capabilities Element 15 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MSDU Signaling Bits 0 -3 Bit 4 Bit 5 -6 Bit 7 Bits 8 -15 TID EOSP TXOP / Queue Size Ack Policy A-MSDU Present TXOP limit TXOP duration QAP PS Buffer size Queue Size Æ QOS Control field bit 7 ■ ■ ■ Indicates the presence/absence of A-MSDU Bit 7 is formerly reserved Valid in DATA type/QOS Subtype frames: • • Submission Qo. S Data+CF-Ack Qo. S Data+CF-Poll Qo. S Data+CF-Ack+CF-Poll 16 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MSDU Frame Format • Efficient Structure • MSDUs of the same TID can be aggregated • MSDUs with differing SA/DA can be aggregated Submission 17 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Enhanced BA Mechanism Æ Æ Implicit BAR: The originator may omit the inclusion of a BAR frame in an aggregated frame and set Qo. S ack policy to “Normal Ack”. Compressed BA: Defines a compressed variant of the 802. 11 e BA MPDU. Partial State for Immediate BA reduces complexity of recipient “No Ack” for Delayed BA Aggregation frame D 1 Initiator D 2 D 3 D 4 SIFS Compressed BA Responder 8 octets Frame Control Duration/ ID RA Compressed Submission TA BA Control Ack Policy 18 BA Starting Seq. Control Block. Ack. Bitmap FCS TID Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP/MTBA Æ Power-save Multi-Poll (PSMP) ■ PSMP sequence allows the AP to create effective service periods for S-APSD • Benefits from statistical multiplexing of retries, activity cycles and rate variations • In the Vo. IP application, benefit is up to 2 x resulting from sharing an allocation for retries within the current aggregate SP Æ Multi-TID Block Ack (MTBA) ■ ■ ■ Submission Allows for single frame to respond to (implicit) BAR for multiple TID Used only within PSMP sequences Shall be used within PSMP sequences instead of BA 19 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP Frame Format Submission 20 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MTBA Frame Format Submission 21 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP with MTBA Æ Æ Æ MTBA efficiently carries BA for multiple TIDs PSMP schedules when a STA receives and when it may transmit. DL Acknowledgement scheduled in the uplink & vice versa ■ Submission UL data acknowledged by following PSMP sequence 22 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Reverse Direction (RD) Æ Allows a STA to share its TXOP with another STA ■ ■ Æ The most significant benefit is obtained if this reduces the number of channel access attempts Some benefit from aggregating BA and Data together Signalled by: ■ ■ ■ Submission Duration/ID field, which carries the remaining duration of the TXOP HT control Field, which carries: RDG / More PPDU, AC constraint Qo. S Control field, which carries TID of traffic allowed in this RD 23 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RD Example Exchange Submission 24 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 HT Control Field – Format Submission 25 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MIMO Power Save Æ Æ Modes: Disabled (fully MIMO capable), Static, Dynamic Signalled: ■ ■ Æ Æ HT Capabilities Element MIMO Power Save management action frame Static: Device notifies its peers of changes in its MIMO power-save state Dynamic: Device requires RTS/CTS sequence to bring it out of MIMO power-saving to fully capable Submission 26 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MIMO Power Save Example Submission 27 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Link Management Æ Link ■ MCS Request/Feedback protocol Æ Tx ■ ■ ■ Adaptation BF Support Zero-Length sounding frame (ZLF) Calibration Procedures Channel State Feedback Æ Antenna Submission Selection Support 28 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MCS Request / Feedback Protocol Æ Signalled ■ ■ ■ in HTC Field Timing of response MRQ is unconstrained Unsolicited MRS response permitted Sequence number MFS to pair MRQ and MFB response MFB Submission 29 Description MCS request Sequence number of MCS request 000 -110 Seq. Number of feedback or “unsolicited” (111) MCS feedback Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Calibration / Tx BF Control Fields Name Description Calibration Position in a calibration sequence: none, start, response, complete Calibration Incremented for each new Sequence ID calibration procedure Feedback Request Position of CSI feedback: none, unsolicited, immediate, aggregated CSI / Steering Type of feedback: CSI, uncompressed steering, compressed Submission 30 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Calibration Submission 31 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Explicit Channel State Feedback AP Computes MCS and Steering matrices AP Computes Demod Solution Un-Steered HT-LTF AP Unsteered HT-DATA Sounding PPDU Steered HT-DATA RTS+HTC/CRQ Data/CRQ/MRQ Unsteered HT-LTF Client Unsteered HT-DATA …………………. . . - CTS in AMPDU with channel feedback Client computes demod solution Client collects CSI Submission Steered HT-LTF 32 Client computes MCS and collects CSI Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Zero Length Frame Æ Æ Zero Length Frame (ZLF) is a PPDU containing a 0 -byte PSDU Reduces overhead of sending a sounding frame after a non-sounding (legacy) frame Reduces overhead when a sequence of sounding frames needs to be sent (antenna selection) Controlled by the ZLF announcement bit in the HT Control field. ■ Submission Addressing for the ZLF is taken from the previously received MPDU 33 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Antenna Selection (AS) Support Æ Æ Flexible mechanism at MAC to support antenna selection Optional feature ■ Æ Æ Transparent to PHY Signalled by ASI field in HTC field Allows additional diversity gain with antenna switching ■ Submission Improved performance for stations with more antennas than transmit or receive paths 34 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Signaling Protocol for Transmit AS Consecutive sounding frames Non ZLF + HTC with ZLF bit= 1 TXASSI TX or SIFS TXASSI Segmented sounding PPDU RX Æ Æ ZLF … SIFS TXASSI SIFS Segmented sounding PPDU AS feedback TXASSR (optional) Æ ZLF TX AS sounding request Rx conducts channel estimation The transmitter sends out consecutive sounding frames separated by SIFS in a TXOP over different antenna sets The receiver estimates the subchannel corresponding to each sounding frame The receiver may either explicitly feedback the full size CSI, or the selected antenna indices in a subsequent TXOP Submission 35 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Coexistence Æ Long. NAV Protection Æ L-SIG TXOP Protection Æ ER/NR Protection Æ Greenfield & RIFS operation Æ Rules for response MPDU / EIFS Æ PCO 20/40 Operation Æ Channel selection rules Æ Channel width Management Submission 36 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Long. NAV protection Æ Æ Provides protection of a sequence of multiple PPDUs Provides a solution for. 11 b Comes “for free” with polled TXOP Gives maximum freedom in use of TXOP by initiator Submission 37 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 L-SIG TXOP Protection Æ Æ Æ Æ Optional Feature Establishes PHY-layer protection using HT Mixed mode (MM) PPDUs AP indicates if all STA in its BSS support it Duration implied by legacy SF length value in MM PPDU conveys a duration > current PPDU Value protected also indicated in MAC duration field and all PPDUs (except RTS) locate the same protection end point RTS protection extends to end of CTS to avoid unfairness problems when comparing CCA (legacy) to NAV (HT) Not used with Long. NAV rules Submission 38 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Example of L-SIG TXOP Protection Submission 39 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 ER/NR Protection Æ RTS/Dual CTS mechanism provides protection between ER and NR devices Æ ER AP sends both ER and NR CTS when it receives an RTS Æ ER non-AP STA requires minor changes (CTS timeout) Æ NR non-AP STA requires no changes Submission 40 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RIFS Æ Æ Shorter gap (2 us) than SIFS between PPDUs sent by the same TA AP controls use of RIFS in BSS through “RIFS Mode” bit in Additional HT Info Field ■ ■ Æ RIFS not permitted when there are legacy APSD devices. These may wake and transmit frames during MM RIFS burst Legacy devices may not be able to handle RIFS separation Any RIFS sequence requires prior protection (MAC or LSIG) when legacy devices are associated (signalled in “Operating Mode” field). Submission 41 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Greenfield Æ Æ Æ Ability to receive Green Field PPDU types is an option – signalled in HT Capabilities Shortens PHY overhead, but does not support legacy devices or L-SIG protection STA shall protect any sequence containing GF PPDUs using prior MAC or L-SIG protection if there are legacy devices or non-GF devices present. ■ Submission Such conditions signalled by the AP 42 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 EIFS Protection Æ Want to avoid legacy STA performing EIFS while HT STA are accessing the channel using AIFS ■ ■ AIFS is performed by HT STA after RX MM EIFS is performed by legacy STA after RX MM • Legacy EIFS is longer than AIFS Æ Response frames are legacy-receivable ■ ■ Sent after a MM sequence, this will cancel remaining EIFS at legacy receivers Exceptions: • L-SIG TXOP allows HT response frames (e. g. HT RTS/ HT CTS) • TRQ MPDU generates a HT PPDU response Æ CF-End is legacy receivable ■ ■ ■ Submission Long NAV EPP Cancels both NAV and EIFS at legacy receivers, restoring common starting point for all receiving STA (legacy and HT) 43 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PCO 20/40 Æ Æ Optional feature AP Establishes separate 20 MHz and 40 MHz operating phases ■ ■ Æ 20 MHz phase: allows independent BSS activity on control channel and OBSS on extension channel 40 MHz phase: 40 MHz transmissions across 40 MHz channel with no 20 MHz interference Allows AP to switch PCO-capable STA between 20 & 40 operation ■ Submission 20 MHz STA can only communicate during the 20 MHz phase 44 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PCO 20/40 Operation Submission 45 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Channel width Management Æ Æ Æ AP controls permitted channel width of the BSS statically (non-PCO) or dynamically (PCO) STA can provide a recommendation to its peer to transmit to it using 20 MHz even when it is in a 20/40 mode, for example, due to interference in its locality on the extension channel Uses “Set recommended transmission channel width” management action frame for this purpose Submission 46 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Capabilities Æ HT Capability element defines the capabilities of the sending STA ■ Signalled in the same frame types as the existing capability element. Æ PHY Capabilities Æ MAC Capabilities Submission 47 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PHY Capabilities Æ Æ Æ Æ Æ Supported MCS Set Advanced Coding Short GI for 20 & 40 MHz separately STBC for Rx and Tx separately Supported channel widths Green field support Use of DSSS/CCK PPDU formats in 2. 4 GHz Tx. BF support MCS Feedback support Submission 48 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 MAC Capabilities Æ Æ Æ Æ MIMO power-saving mode Maximum A-MPDU length Maximum A-MSDU length (4 K/8 K) MPDU Density limit PSMP Support STBC control frame support Phased Coexistence Operation (PCO) Support Transition Time for PCO 20/40 switching Submission 49 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Summary Value of selected features Feature Value A-MPDU About 2. 5 × Data/Ack A-MSDU About 20% on top of A-MPDU Reverse Direction Roughly 25% Enhanced BA Roughly 5 -10% PSMP / MTBA Vo. IP call density increase of up to 2 × non-PSMP Submission 50 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Performance Results - Conditions Æ 2 x 2 x 20 and 2 x 2 x 40 mandatory PHY features Æ Compressed BA, Implicit BAR Æ A-MSDU Æ A-PPDU Æ Reverse Direction Æ Reference: 11 -05 -1268 r 1 Submission 51 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Performance Results CC# CC 3 Name List of goodput results for usage models 1, 4 and 6. CC 18 HT Usage Models Supported Non-Qo. S (Measured aggregate throughput / offered aggregate throughput) CC 19 HT Usage Models Supported (number of Qo. S flows that meet their Qo. S requirements) CC 58 HT Spectral Efficiency Submission 52 HCCA (MAC 1) Result 2 x 2 x 20 2 x 2 x 40 SS 1 + (Mbps) 109 194 SS 4 + 111 230 SS 6 + 101 200 SS 1 + (Mbps/ratio) 56/0. 28 141/0. 71 SS 4 + 102/0. 23 221/0. 28 SS 6 + 56/0. 19 155/0. 52 SS 1 + 17/17 SS 4 + 18/18 SS 6 + 39/39 bps/Hz 5. 7 5. 6 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 References Document Title 11 -05/1095 Joint Proposal MAC Specification Joint Proposal MAC Results Joint Proposal MAC Simulation Methodology 11 -05/1266 11 -05/1267 11 -05/1268, 1269, 1270 Submission 53 Joint Proposal MAC 1, MAC 2, MAC 3 results Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Backup Submission 54 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MPDU Rules Æ Single Receiver Address (SRA) aggregation only Æ Use of BA is mandatory for acknowledged data in A-MPDU ■ Implicit BAR gives robust delivery of BAR Æ BA ■ ■ Submission and Data may be aggregated together under Reverse direction rules: BA & Data Under PSMP rules: MTBA & Data 55 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 A-MSDU DA/SA Fields To Fro Add D m r S D e S s s 1 Add r e s s 2 Add r e s s 3 Add r e s s 4 BSS X I D 0 0 DA SA 0 1 DA BSS X I I D D 1 0 BSS SA I 56 D Submission BSS X I D Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RD Rules Æ Æ Æ The initiator chooses whether to grant or not Grant is signalled by RDG flag in HT Control field and limited by remaining duration in TXOP Response can include one or more PPDUs indicated by “More PPDU” flag in HT control field Response is limited to unicast MPDUs addressed to the initiator Response may be constrained to a defined AC (for EDCA use) or any AC (for HCCA use) Error recovery is the responsibility of the initiator Submission 57 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RD Initiator rules (1) Æ Æ The initiator shall ensure that its PPDU transmission and any expected/granted responses fit entirely within the current TXOP (this is implicit in 802. 11 e). The responder shall ensure that its PPDU transmission(s) and any expected responses fit entirely within the RDG duration. When the initiator sets the RDG flag to 1, it shall set the AC Constraint field according to the channel access mechanism used The responder may only transmit Data MPDUs of the same AC as previous data from initiator (AC constraint = 1) or of any TID (AC constraint = 0) Submission 58 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RD Initiator Rules (2) Æ Æ The responder shall not transmit any MPDUs that are not addressed to the initiator (RA). Subject to TXOP constraints, after transmitting a PPDU containing a reverse direction grant, the initiator may transmit its next PPDU a minimum of a SIFS after receiving a response PPDU with the "More PPDU" flag set to 0. ■ Æ I. e. Initiator still owns TXOP if Grantee is done and TXOP limit has not been exceeded PIFS recovery rule for GRANTOR ■ Submission I. e. if responder does not respond, then Grantor may invoke recovery 59 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 RD Responder rules Æ Æ Æ The first PPDU of any response burst shall contain all response MPDUs (e. g. Ack, BA) as required to respond to the previous PPDU. Only the last PPDU of a response burst may contain an MPDU requiring an immediate response (e. g. immediate BA). If the transmission of a frame in a response PPDU requiring an immediate response fails, the responder has to wait until it has the next opportunity to transmit to the initiator before it can retry the transmission. ■ Submission I. e. initiator owns the TXOP and all rights to recovery 60 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Value of RD ** November 2005 results Submission 61 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Value of RD – 2 ** November 2005 results Submission 62 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Value of A-MSDU ** November 2005 results Submission 63 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Value of A-MSDU - 2 Submission 64 ** November 2005 results Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Block Ack Rules Æ Æ HT STA always use compressed BA between themselves HT STA must support at least partial state immediate BA ■ ■ ■ Æ Immediate Full State optional (no signalling) Delayed Full State optional (capability) PSMP/MTBA (capability) Implicit BAR makes explicit BAR unnecessary in aggregates Submission 65 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP Rules Æ Æ AP only includes STA within PSMP if STA is capable, as advertised in HT Capabilities. AP obeys minimum DLT 2 ULT. AP may set bits in “TID set” field to provide recommendation to STA for use of ULT AP uses EOSP bit to signal end of DATA delivery to STA ■ Æ Æ Ack Policy setting in DLT frames is “PSMP/MTBA” Service Interval granularity ■ Æ i. e. permission to return to sleep Advertised by AP to allow STA to determine appropriate TSPEC service interval request to match AP PSMP service intervals PSMP may be used in context of U-APSD or S-APSD Submission 66 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP Sequence Submission 67 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP resource request example Submission 68 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 PSMP retransmission example Submission 69 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 HT Control Field – Rules Æ HT Control Field is a 4 -byte addition to the end of the MPDU header. Æ Signalled through the “Order/HTC” bit in the MPDU header Æ Valid in control and Qo. S data subtypes ■ Submission Not valid in non-Qo. S data, for which the Order bit retains its original meaning 70 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Antenna Selection (AS) Support Æ Flexible mechanism at MAC to support all kinds of antenna selection schemes Æ Optional feature ■ Transparent to PHY Æ Signalled by ASI field in HTC field Æ Diversity gain is achieved ■ Submission Diversity is important in high SNR, and WLAN usually operates in high SNR environments 71 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Antenna Selection Signaling Protocol For TX antenna selection Æ The transmitter sends out consecutive sounding frames separated by SIFS in a TXOP over different antenna sets The receiver estimates the subchannel corresponding to each sounding frame The receiver may either explicitly feedback the full size CSI, or the selected antenna indices in a subsequent TXOP ■ ■ ■ For RX antenna selection Æ ■ ■ ■ Submission The receiver sends out a RX AS sounding request indicating the total number of sounding frames required The transmitter responds with the corresponding number of sounding frames in its subsequent TXOP The receiver uses different antenna sets to receive these sounding frames, estimates channel state information and conducts the antenna selection. 72 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Frame Exchange Sequence for TX Antenna Selection Consecutive Sounding frames Non ZLF + HTC with ZLF bit= 1 TXASSI TX or TXASSI SIFS Segmented sounding PPDU RX … SIFS TXASSI ZLF Segmented sounding PPDU TXASSI SIFS Segmented sounding PPDU AS feedback TXASSR (optional) Submission TX AS sounding request 73 Rx conducts channel estimation Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Frame Exchange Sequence for RX Antenna Selection Consecutive Sounding frames Non ZLF + HTC with ZLF bit= 1 RXASSI TX or SIFS RXASSI ZLF RXASSI SIFS Segmented sounding PPDU RXASSR RX AS sounding request Submission … SIFS 74 Rx conducts channel estimation and AS Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Response MPDU Rule Æ Unaggregated responses are legacy or legacy duplicate format ■ ■ Submission RTS/CTS A-MPDU/BA Avoids EIFS fairness issues with legacy devices Allows waking legacy device to determine NAV setting part way through an AMPDU/BA/A-MPDU/BA burst 75 Fischer (Broadcom), Stephens (Intel) et. al.

January 2006 doc. : IEEE 802. 11 -05/1165 r 5 Channel selection rules Æ Æ AP Chooses channel position and width based on an observation of its environment Selects 20 MHz or 20/40 MHz operation ■ Æ Æ Under 20/40, selects one 20 MHz half as the “control” channel and one as the “extension” channel Can choose to co-exist with legacy BSS on the control channel (non-PCO operation) or on both control and extension channels (PCO operation) May only overlap another HT BSS using the same values for extension and control channel Submission 76 Fischer (Broadcom), Stephens (Intel) et. al.