doc.: IEEE /0410r2 Submission March 2011 Slide 1 Data Transmission Protection on the IEEE ac MU-MIMO Downlink Date: Authors: Haiguang Wang, Institute for Infocomm Research

doc.: IEEE /0410r2 Submission March 2011 Slide 2 Abstract The presentation addresses CID 1337 for the hidden node issues in MU-MIMO, where a few STAs receiving MU- PPDU grouped according to a group ID We propose to Allow group ID being transmitted in RTS (no change to frame structure) This enables efficient RTS-CTS protection for MU- MIMO –AP transmits Single RTS with group ID embedded –Each BSS returns a CTS Haiguang Wang, Institute for Infocomm Research

doc.: IEEE /0410r2 Submission March 2011 Haiguang Wang, Institute for Infocomm ResearchSlide 3 Recap, IEEE ac MU-MIMO IEEE ac focus on high speed data transmission –Transmission speed up to 1 Gbps –Radio bandwidth up to 160 MHz –Use MU-MIMO technology With MU-MIMO technology, AP can transmit multiple data packets to multiple stations at the same time.

doc.: IEEE /0410r2 Submission March 2011 Slide 4 Hidden Node Issues with MU-MIMO Haiguang Wang, Institute for Infocomm Research One of the problems with MU-MIMO technology is how to protect data transmission. –IEEE use contention-based data transmission. –Legacy RTS/CTS can only provide partial protection over the MU-MIMO downlink transmission. –Collision may happen when legacy stations is hidden to ac stations. AP1 STA2 STA3 STA1 AP2 STA4 RTS CTS Collision MU-MIMO Downlink RTS protection range CTS protection range

doc.: IEEE /0410r2 Submission March 2011 Slide 5 Possible Transmission Protection for ac MU-MIMO Downlink Haiguang Wang, Institute for Infocomm Research A few schemes can be used for transmission protection of ac MU- MIMO downlink, they are: –Legacy RTS/CTS –Single RTS Multiple CTS –Multiple RTS Multiple CTS

doc.: IEEE /0410r2 Submission March 2011 Slide 6 Single RTS Multiple CTS (1) Haiguang Wang, Institute for Infocomm Research

doc.: IEEE /0410r2 Submission March 2011 Slide 7 Single RTS Multiple CTS (2) Haiguang Wang, Institute for Infocomm Research RTS xIFS time AP STA1 STA2 STA3 CTS xIFS time NAV protection CTS xIFS time We can also consider to send CTS at the same time. NAV distributing

doc.: IEEE /0410r2 Submission March 2011 Slide 8 Addressing Multiple Stations in RTS Haiguang Wang, Institute for Infocomm Research Single RTS multiple CTS can provide a better protection on data transmission than legacy RTS/CTS scheme. However, we need solve following issues: –Address multiple stations in RTS. –Compatible with legacy stations

doc.: IEEE /0410r2 Submission March 2011 Slide 9 Group Address Haiguang Wang, Institute for Infocomm Research IEEE ac task group has defined a group ID at PHY layer. A group of stations may be assigned to the same group ID, which indicates that data transmitted in the packet are sent to the stations in this group. Group ID is sent in PHY layer

doc.: IEEE /0410r2 Submission March 2011 Slide 10 Using RTS-to-Self and Group ID for Addressing Haiguang Wang, Institute for Infocomm Research AP uses group ID directly as group MAC address. –To avoid confusion caused by station with MAC address that is equivalent to a group ID, we propose to use RTS-To-Self with group ID in TA field. AP1 STA2 STA3 STA1 AP2 STA4 RTS

doc.: IEEE /0410r2 Submission March 2011 Slide 11 Advantage Haiguang Wang, Institute for Infocomm Research No change to RTS frame structure Simple in the implementation. Save the signaling exchange for group addressing. Compatible with legacy system

doc.: IEEE /0410r2 Submission March 2011 Slide 12 Summary Haiguang Wang, Institute for Infocomm Research In this proposal, we have proposed to utilize group ID addressing multiple stations with a single RTS packet. It is compatible to legacy stations. It enables efficient RTS-CTS transmission for hidden node protection in MU-MIMO

doc.: IEEE /0410r2 Submission March 2011 Haiguang Wang, Institute for Infocomm ResearchSlide 13 Strawpoll Are you in favor of allowing using group ID in RTS? Y N A