Haiguang Wang, Jaya Shankar, Zhongding Lei A Method for Data Transmission Protection on the IEEE 802.11ac MU-MIMO Downlink Haiguang Wang, Jaya Shankar, Zhongding Lei
Content Background Protect Data Transmission on IEEE 802.11ac MU-MIMO downlink Summary
IEEE 802.11ac IEEE 802.11ac 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.
Issues with MU-MIMO Technology One of the problems with MU-MIMO technology is how to protect data transmission. IEEE 802.11 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 802.11ac stations. RTS protection range CTS protection range RTS Collision CTS AP1 STA1 STA3 AP2 STA2 STA4 MU-MIMO Downlink
Possible Transmission Protection for 802.11ac MU-MIMO Downlink A few schemes can be used for transmission protection of 802.11ac MU-MIMO downlink, they are: Legacy RTS/CTS Single RTS Multiple CTS Multiple RTS Multiple CTS
Single RTS Multiple CTS (1)
Single RTS Multiple CTS (2) We can also consider to send CTS at the same time. NAV protection AP RTS xIFS time STA1 CTS xIFS time STA2 CTS xIFS time STA3 CTS NAV distributing
Addressing Multiple Stations in RTS 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
Group Address IEEE 802.11ac 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
Using RTS-to-Self and Group ID for Addressing 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. RTS AP1 STA1 AP2 STA3 STA2 STA4
Advantage Simple in the implementation. Save the signaling exchange for group addressing. Compatible with legacy system
Summary In this proposal, we have propose a solution for IEEE 802.11ac standard in addressing multiple stations with a single RTS packet. The solution is compatible to legacy stations. We have also proposed solutions that may encounter in designing of Single RTS Multiple CTS.