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Strawmodel 802.11ac Specification Framework

Strawmodel 802.11ac Specification Framework. Date: 2009-05-13. Authors:. Introduction. A draft 11ac specification framework is presented according to the spec framework methodology described in document 09/0237r0. 11ac Specification Framework Development.

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Strawmodel 802.11ac Specification Framework

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  1. Strawmodel 802.11ac Specification Framework Date: 2009-05-13 Authors:

  2. Introduction • A draft 11ac specification framework is presented according to the spec framework methodology described in document 09/0237r0

  3. 11ac Specification Framework Development • Step 1: TGac specifies Key Technologies and Physical layer Parameters • Step 2: TGac specifies Specification Framework according to Framework Specification Methodology • Step 3: Form TGac Ad-hoc group(s) to work on Framework elements This document is a first attempt at steps 1&2

  4. Key Assumptions • Build upon 802.11n as much as possible to increase probability of acceptance by the 802.11ac group • Use 11n MIMO-OFDM parameters for 20/40 MHz channels • same symbol time, number of subcarriers, subcarrier spacing, pilots, guard interval • Make data flow as close as possible to 802.11n • 11ac MAC changes build upon EDCA • Ensure interoperability and coexistence with 802.11n

  5. Preliminary Spec Framework;Topics for Consideration • MU-MIMO • downlink / uplink / distributed • maximum number of users • maximum number of streams per user • 500 Mbps single-user throughput target • synchronization • power control • channel state information feedback • explicit channel state information feedback with more resolution than current 11n to accommodate higher required SNR for MU-MIMO • Channel Bandwidth • Single User bandwidth (20/40/80 MHz) • Multi-channel - Non-contiguous groups of 20/40 MHz channels with synchronous or asynchronous transmission across channel groups • OFDMA • CCA

  6. Preliminary 11ac PHY Block Diagram

  7. Preambles • Purpose • Provide training capability for timing, gain setting, frequency synchronization and channel estimation • Required Inputs • Control parameters: preamble type, bandwidth, number of streams • Expected Outputs • Preamble samples in frequency domain or time domain • Proposed Performance Metrics • Length of preamble • Coexistence with 11a/n • Gain setting accuracy • PER versus SNR curves • Robustness to front-end impairments • Dependencies • Choice of channel bandwidth, types of MU-MIMO, maximum number of spatial streams per user • Possible Directions • Design mixed-mode and/or greenfield preambles to handle MU-MIMO and/or more than 4 spatial streams for a single user

  8. Parsing and Interleaving • Purpose • Parse and interleave data per user • Required Inputs • Encoder output bits • Expected Outputs • Interleaved bits • Proposed Performance Metrics • PER versus SNR curves • Dependencies • Choice of channel bandwidth and maximum number of spatial streams per user • Possible Directions • Extend 11n interleaver for higher bandwidth and/or more than 4 spatial streams

  9. Coding • Purpose • Provide coding gain • Required Inputs • Input bits • Expected Outputs • Coded bits • Proposed Performance Metrics • PER versus SNR curves • Coding/decoding complexity • Dependencies • None • Possible Directions • One option to reach the 500 Mbps single-user throughput would be to use a higher coding rate like 7/8 • Another choice to make is whether to keep encoding data per user as in 11n, or do per-stream coding

  10. STBC • Purpose • Provide TX diversity • Required Inputs • Frequency domain QAM subcarrier values per user • Expected Outputs • STBC encoded subcarrier values • Proposed Performance Metrics • PER versus SNR curves • Dependencies • Maximum number of spatial streams per user • Possible Directions • Extend 11n STBC for more than 4 spatial streams

  11. Spatial Mapping and Cyclic Delays • Purpose • Precode spatial streams in order to provide MU-MIMO or to provide TX diversity or beamforming in case of single-user transmission • Required Inputs • Frequency domain subcarrier values • Expected Outputs • Precoded frequency domain subcarrier values • Proposed Performance Metrics • PER versus SNR curves • Dependencies • Maximum number of users and maximum number of spatial streams per user • Possible Directions • MMSE SDMA precoding • For single-user transmission, extend 11n cyclic delays for more than 4 spatial streams

  12. Pilots • Purpose • Phase reference within data symbols • Required Inputs • Control parameters: number of streams, bandwidth • Expected Outputs • Pilot values • Proposed Performance Metrics • PER versus SNR curves • Dependencies • Choice of channel bandwidth and maximum number of spatial streams per user • Possible Directions • Extend 11n pilots for higher bandwidth and/or more than 4 spatial streams

  13. Preliminary MAC Spec Framework Overview Downlink MU-MIMO Uplink MU-MIMO Multi-User Aggregation TDM/FDM Uplink and Downlink Block-Ack Synchronous Contiguous Multi-channel Synchronous Non-Contiguous Multi-channel Asynchronous Non-Contiguous Multi-channel Distributed STA Communication Transmit Power Control Dynamic Frequency Selection Channel Switching Link Adaptation Channel Sounding VHT Control Field OBSS Management Flow Control

  14. Downlink MU-MIMO • Purpose • Enable efficient MU-MIMO for Downlink Data Transmission • Required Inputs • NA • Expected Outputs • Downlink MU-MIMO transmission protocol including • Control Message sequence • Frame formats and Field Descriptions • Coexistence with 11a/n • Proposed Performance Metrics • Maximum Downlink Data Throughput at the MAC SAP • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Peak-to-average power of transmitted signal • Dependencies • Channel sounding protocol • Channel reservation protocol for multiple STAs • UL Block Ack for multiple STAs • VHT SIG Field Design • Possible Directions • TBD

  15. Uplink MU-MIMO Protocol • Purpose • Enable efficient MU-MIMO for Uplink Data Transmission • Required Inputs • NA • Expected Outputs • Uplink MU-MIMO transmission protocol including • Control Message sequence • Frame formats and Field Descriptions • Coexistence with 11a/n • Proposed Performance Metrics • Uplink Data Throughput at the MAC SAP • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • Channel sounding protocol • Channel reservation protocol for multiple STAs • DL Block Ack transmission to multiple STAs • VHT SIG Field Design • Possible Directions • TBD

  16. Multiuser Aggregation TDM/OFDMA • Purpose • Enable 20/40/80 MHz downlink/uplink transmission to/from multiple STAs • Required Inputs • NA • Expected Outputs • TDM/FDM Frame Format to support transmission to/from multiple STAs. • Control Message sequence, including CCA methodology. • Frame formats and Field Description. • Proposed Performance Metrics • Maximum DL/UL Data Throughput at the MAC SAP • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements. • Dependencies • VHT SIG Field design • Block ACK Scheduling • Possible Directions • TBD

  17. Synchronous Contiguous Channel Access • Purpose • Enable synchronized uni-directional access on a set of contiguous channels • Required Inputs • NA • Expected Outputs • CCA for multiple contiguous channels • Protocols for assigning STAs to channels • Protocols for aggregating channels to a single STAs • Protocols for synchronizing uplink or downlink access on multiple channels. • Proposed Performance Metrics • Uplink/Downlink Data Throughput at the MAC SAP • Channel usage efficiency • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • Multiuser Aggregation TDM/OFDMA • Possible Directions • TBD

  18. Synchronous Non-contiguous Channel Access • Purpose • Enable synchronized bi-directional access on a set of non-contiguous channels • Required Inputs • NA • Expected Outputs • CCA for multiple contiguous/non-contiguous channels • Protocols for assigning STAs to channels • Protocols for aggregating channels to a single STAs • Protocols for synchronizing uplink/downlink access on multiple channels. • Proposed Performance Metrics • Uplink/Downlink Data Throughput at the MAC SAP • Channel usage efficiency • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • TBD • Possible Directions • TBD

  19. Asynchronous Non-contiguous Multi-Channel Access • Purpose • Enable an AP to support multiple asynchronous channels that are non-contiguous • Required Inputs • NA • Expected Outputs • Control Message sequence, including CCA Methodology • Frame formats and Field Description. • Proposed Performance Metrics • Uplink/Downlink Data Throughput at the MAC SAP • Channel usage efficiency • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • VHT SIG Field design • Block ACK Scheduling • Possible Directions • TBD

  20. Distributed STA Communication • Purpose • Enable simultaneous communication between multiple STA pairs using spatial or frequency separation • Required Inputs • NA • Expected Outputs • Protocol for co-ordinating communication between multiple STAs • Control Message sequence, including CCA Methodology • Frame formats and Field Description. • Proposed Performance Metrics • Uplink/Downlink/Direct-link Data Throughput at the MAC SAP • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • 11z TDLS • Possible Directions • TBD

  21. Transmit Power Control • Purpose • Enable transmit power control at STA and AP for • Power save • UL MU-MIMO • Required Inputs • NA • Expected Outputs . • Transmit power control protocol • Proposed Performance Metrics • Uplink MU-MIMO throughput • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • UL MU-MIMO • Possible Directions • TBD

  22. Dynamic Frequency Selection • Purpose • Enable 802.11ac AP to select a suitable channel or set of channels for operation • Required Inputs • NA • Expected Outputs . • Frequency selection algorithm • Proposed Performance Metrics • TBD • Dependencies • Regulatory requirements 11a/11h • Possible Directions • TBD

  23. Channel Switching • Purpose • Enable channel switching at STA and AP • Required Inputs • NA • Expected Outputs . • Protocols for AP controlled channel switching • Protocols for autonomous STA channel switching. • Proposed Performance Metrics • Per STA uplink and downlink throughput • Channel utilization efficiency • Dependencies • NA • Possible Directions • TBD

  24. Link Adaptation • Purpose • Enable link adaptation for optimal MCS selection • Required Inputs • NA • Expected Outputs . • Signaling for link adaptation • Proposed Performance Metrics • Uplink/Downlink Data Throughput at the MAC SAP • Dependencies • DL/UL MU-MIMO protocols • Multichannel protocol • Possible Directions • TBD

  25. Channel Sounding Protocol • Purpose • Efficiently transmit channel sounding from multiple STAs to an AP • Required Inputs • NA • Expected Outputs . • Protocol for obtaining channel sounding from multiple STAs • Frame formats for control messages to obtain channel sounding. • Explicit/Implicit Sounding Frame Format • Proposed Performance Metrics • Channel Sounding latency and time overhead • Dependencies • DL and UL MU-MIMO protocols • Transmit power control • Possible Directions • UL MU-MIMO for implicit channel sounding

  26. UL Block ACK • Purpose • Enable efficient scheduling of UL Block ACKs from multiple STAs in response to a downlink MU-MIMO/TDM/FDM transmission • Required Inputs • NA • Expected Outputs • Resource allocation protocol for UL Block ACKs • Proposed Performance Metrics • Block ACK time overhead • Dependencies • DL MU-MIMO • TDM/FDM • Possible Directions • MU-MIMO for UL Block ACK

  27. DL Block ACK • Purpose • Enable efficient scheduling of DL Block ACKs to multiple STAs in response to an uplink MU-MIMO/TDM/FDM transmission. • Required Inputs • NA • Expected Outputs • Resource allocation protocol for DL Block ACK • Proposed Performance Metrics • Block ACK time overhead • Dependencies • UL MU-MIMO • TDM/FDM Multichannel protocols • Possible Directions • MU-MIMO for DL Block Ack

  28. MAC Control Field • Purpose • VHT MAC control field to be added to the MAC header to indicate parameters/signaling specific to 802.11ac • Required Inputs • Downlink/Uplink MU-MIMO protocol • Multichannel protocol • Multi-STA block ack protocols • Expected Outputs • Format of VHT MAC control field. • Proposed Performance Metrics • VHT MAC Control Field Overhead (Bits) • Dependencies • NA • Possible Directions • Add VHT control field to header. Signal the presence of VHT control field through HT-control header.

  29. VHT Flow Control • Purpose • Enable STA/AP to control the rate of packets arriving at it. • Required Inputs • NA • Expected Outputs • Flow control protocol • Proposed Performance Metrics • Flow Control Time Overhead • Uplink/Downlink Data Throughput at the MAC SAP • Packet transfer latency from the Tx MAC SAP to Rx MAC SAP • Packet loss rate subject to application latency requirements • Dependencies • NA • Possible Directions • Ethernet pause packet protocol

  30. OBSS Management • Purpose • Preserve or increase the system throughput of OBSS's when compared to the case of 802.11n OBSS. • Required Inputs • TBD • Expected Outputs • OBSS management protocol • Proposed Performance Metrics • Throughput and delay statistics of OBSS's in the presence of BSS • Dependencies • Downlink/Uplink MU-MIMO protocol • Multichannel protocol • Possible Directions • - Protocol considering multichannel, MU-MIMO and 802.11aa • OBSS protocols Slide 30

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