Beam training procedure for 60GHz mm-wave communication (TGad)

1. Beam training procedure for 60GHz mm-wave communication (TGad) Authors: Date: 2010-05-15 Junyi Wang, NiCT

2. Abstract Overview of beamforming (BF) related contributions for 802.11ad and suggestions for BF proposal based on those contributions. Junyi Wang, NiCT

3. In IEEE Std 802.15.3c™-2009, a BF protocol is specified on the top of multiple PHY modes. • In 09/0572r0, the authors show that in 60GHz, most usages (07/2988r4) require directional communication in order to meet link budget requirements. • In 09/0572r0, the authors also believe that TGad should reuse as much as possible from 802.11+amendments. • In 09/1153r0, the authors conclude that BF is one of the most important features in the TGad 60GHz specification and will be decisive in enabling successful 60GHz products. Introduction (1/2) Junyi Wang, NiCT

4. In 09/1153r0, the authors summary the beamforming requirement in TGad • One beamforming protocol for all usages/scenarios • The BF protocol shall support different antenna types and does not assume antenna reciprocity • The BF protocol shall allows fast BF link (re-)establishment and tracking • The BF protocol should accommodate devices/usages with different levels of complexity • The BF protocol should supports pre-network entry and post-network entry BF • In 10/0231r3, the authors propose to use 802.11a/b/g/n to assistant 802.11ad for signalling. Introduction (2/2) Junyi Wang, NiCT

5. Network model Infrastructure mode Ad-hoc mode • In infrastructure mode, a beamformed link shall be set up between Access Point (AP) and any Station (STA). • In Ad-hoc mode, a beamformed link shall be set up between any two STAs. Junyi Wang, NiCT

6. The objective of the proposed BF is to find the optimal transmit and receive antenna weight vector through MAC operation in order to optimize a cost function that measures the link quality metric. In this paper, signal to interference plus noise ratio (SINR) is selected as the metric. Beamforming model Junyi Wang, NiCT

7. All STAs shall support one or more directional antenna patterns, which are generated by the pre-defined beam codebooks. • A beam codebook is a matrix where each column specifies a BF weight vector. Each column also specifies a pattern. • Either of the following ways shall be supported for signaling. • All BF capable STAs support 2.4G/5G WLAN (IEEE 802.11a/b/g) • At least AS support omni-transmission with low date rate with advanced modulation and coding scheme that compensates for the lack of antenna gain. Basic assumptions for BF Junyi Wang, NiCT

8. The BF operation starts from either of following initial status by acquiring synchronization with AS Initial status 2.4GHz/5GHz Omni By switching directional pattern to acquiring beacon in 60Ghz Through 2.4G/5G omni Junyi Wang, NiCT

9. Beam training between two STAs Junyi Wang, NiCT

10. Beam training between AP and STA Junyi Wang, NiCT

11. Beam refinement Junyi Wang, NiCT

12. Training sequences • The PLCP preamble can used as the training sequences for each direction. Based on channel status, the either long PLCP preamble (144 bits, 144 us) or short PLCP preamble (72 bits at 1Mbps) can be selected. • Training starting time • The training shall start after receiving BFRsp or BFFdbk command following by a “SIFS” interval. • Training procedure • Supposing beamformer has M directions, beamformee has N directions. Each training period is composed of M cycles of N repetitions. Each cycle shall be sent from each of beamformer’s transmit directions. The repetitions shall be received by each of receive direction of beamformee. Training Junyi Wang, NiCT

13. Address 1: the address of the source • Address 2: the address of the destination • Address 3: the address of the BF target • Rqt/Rsp: Set to 1 when it is BFRqt command, otherwise set to 0 • BF capable: Set to 1 when the STA is BF capable. • # of Tx beams: Number of transmit beam pattern of the beamformer. • # of Rx beams: Number of receive beam pattern of the beamformer. • More training: Set to 1 when the selected is refinable, otherwise set to 0. Note: some of the beamforming ralated fields may be omitted if the source has notintention to do the beamforming but just broadcast the information BFRqt/BFRsp frame format Junyi Wang, NiCT

14. Address 1: the address of the source Address 2: the address of the destination Address 3: the address of the BF target Best pattern ID: the index of the best pattern SNR of best pattern: the SNR of the best pattern, for beamformer to select proper modulation and coding scheme. BFFdbk frame format Junyi Wang, NiCT

15. STA1 is BF capable, however STA2 is not • STA2 shall help STA1 finish BF operation by using omni transmission. • STA1 sets “more training” field to 1, however STA2 sets to 0. • STA2 could not refine its transmit pattern into finer beam. STA2 shall use his latest found pattern to help STA1 finish BF operation, in this case, STA2 shall set the # of Tx beam and # of Rx beam to 1. Some rules for some special cases Junyi Wang, NiCT

16. The document suggests a BF protocol on the top of IEEE 802.11 MAC. The proposed BF protocol is beam codebook based proposal, which selects the best beam pattern from pre-defined beam codebook, and setup a beamformed communication link between any STAs. The proposed BF protocol support different level of codebook complexities, no training stage limitation. STAs are able to request further beam refinement as long as they need. The proposed BF protocol can also be extended to support AP directional transmission. Conclusions Junyi Wang, NiCT

17. References • 11-07-2988-04-00-00ad Wi-Fi Alliance (WFA) VHT Study GroupUsage Models • 11-09-0572-00-00-00ad MAC Channel Access in 60 GHz • 11-09-1153-00-00-00ad Motivation and Requirements on 60 GHz Beamforming • 11-10-0259-02-00-00ad 802.11ad New Technique Proposal • IEEE Std 802.15.3c™-2009 Junyi Wang, NiCT

18. Do you support inclusion of beamforming technique, as described in 10/0xxxr0 in the TGad draft amendment? Yes: . No: . Abstain: . Straw poll Junyi Wang, NiCT