Fast Session Transfer Date: 2010-04-30 Authors: May 2010 March 2010 doc.: IEEE 802.11-10/0xxxr0 May 2010 Fast Session Transfer Authors: Date: 2010-04-30 L. Cariou, Orange Labs Yuichi Morioka, Sony Corporation

March 2010 doc.: IEEE 802.11-10/0xxxr0 May 2010 Abstract Collaboration between 2.4/5 and 60 GHz bands allows the 802.11 user experience to be met by seamlessly providing both the wide coverage of WLAN and the very high throughput of 60 GHz when available A key merit of 802.11.ad is that it can build on past successful standards e.g. 802.11a/n/ad system This will provide many new market opportunities for the 802.11.ad standard In [1] and [2] we introduced several use cases dedicated to fast session transfer. A method of fast session transfer is proposed which enables very fast transparent switching to deal with user mobility, dynamic channel conditions and to allow joint management of multiple bands L. Cariou, Orange Labs Yuichi Morioka, Sony Corporation

Use case 1: FST with a switchable interface in STA Media server Switchable interface Single link either at 5 or 60 FTTH Set-top box AP WiFi 60GHz ( 1 Gbps) WiFi 5GHz ( 500 Mbps) Concurrent dual interfaces Slide 3 presentation title 3 3

Use case 2: FST with concurrent dual interfaces in STA Media server Concurrent dual interfaces Two links, at 5 and 60 FTTH Flow transfer between interfaces or bonding of the two interfaces Set-top box AP WiFi 60GHz ( 1 Gbps) WiFi 5GHz ( 500 Mbps) Concurrent dual interfaces Slide 4 presentation title 4 4

Use cases 1&2: Switch from 2.4/5 to 60GHz or from 60 to 2.4/5GHz Band selection for all flows of a station (stations with only one band active at a given time (Switchable interface) or stations with multiple bands active simultaneously at a given time) AP-STB either in 2.4/5 GHz band or in 60 GHz band (one at a time) Band selection for each flow of a station separately (only stations with multiple bands active simultaneously at a given time) Multiple HD flows between AP and STB either in 2.4/5 GHz band or in 60 GHz band Session transfer of some HD flows in case of saturation of 2.4/5GHz or 60GHz Band selection may be based on (a) maintaining coverage with user mobility, (b) dynamically changing channel quality, (c) throughput enhancement, (d) load balancing between bands, etc  We believe that this interface convergence will improve the overall home network In this presentation, we only consider the case 1 with an AP concurrent dual band a STA with switchable interface Case 2 is considered in [3]. Slide 5

Requirements on fast session transfer Requirements for speed of fast session transfer For video applications: 1080p 60Hz => frame every 16.6 ms Assuming packet loss: latency between 5 and 10 ms For VoIP applications: Maximum acceptable BSS transfer for VoIP roaming is 50 ms For gaming applications, distributed storage or contents sharing: Same constraints as for video  Session transfer should not exceed 5 to 10 ms Quite severe constraint: needs to be better than 11r Other requirements Switch should be able to be initiated by either device in a link (AP or STA) Slide 6

How to perform the fast session transfer Example scenario: One AP working at both 60 GHz and at 5 GHz link to TV at 5GHz (red) link to laptop at 60GHz (blue) to be switched to 5GHz BSSID SSID Encryption key AID database BSSID SSID Encryption key AID database 5 GHz 60 GHz 5GHz 5GHz 60GHz f f AID1 BSSID SSID Encryption key AID1 BSSID SSID Encryption key Slide 7

How to perform the fast session transfer Required functions for FST:  Preparation phase: Exchange of FST capabilities and FST negotiation for each link prior to transmission. We believe the negotiation should lead to the direct acceptance of future switches, to suppress the need to provide a response when a switch is requested Sharing of the association parameters between the two bands To speed up the process by removing the need for disassociation/re-association during the switch Definition in STA of a unique logical MAC address, switchable from one interface to another  FST phase (phase during which FST can be done): Report request/response on one band/channel of particular metrics (such as the load and SNR) of the other band/channel Triggering of the session transfer by the transmission of a signal frame No need for a response to the trigger frame because of the prior negotiation No need for disassociation/re-association because of the sharing of association parameters Slide 8

How to perform the fast session transfer Sharing of association parameters (1/2) Split between association function and forwarding function Association to an AP, independently of the current interface/band: Negotiation of MAC parameters (security, power save, ….) Reception of a unique AID, whatever the band/channel Slide 9

How to perform the fast session transfer Sharing of association parameters (2/2) BSSID SSID Encryption key AID database BSSID SSID Encryption key BSSID SSID Encryption key Trigger signal frame f f Association parameters match AID1 BSSID SSID Encryption key AID2 BSSID SSID Encryption key Slide 10

How to perform the fast session transfer Forwarding (1/2) Definition in FST STA of a unique logical MAC address, switchable from one interface to another Definition in AP of a common MAC with a forwarding table indicating the active interface of a FST STA AP common MAC MAC addr MAClog0 5GHz MAC 5 MAC 60 MAC_ad0 60GHz PHY 5 PHY 60 11ad STA PHY60 MAC 60 MAC addr: MAC_ad0 FST STA PHY 5 PHY 60 MAC 5 Physical MAC addr: MAC1 MAC 60 Physical MAC addr: MAC2 Logical MAC addr: MAClog0 IP IP addr linked to the unique logical MAC addr: MAClog0

How to perform the fast session transfer Forwarding (2/2) Definition in FST STA of a unique logical MAC address, switchable from one interface to another Definition in AP of a common MAC with a forwarding table indicating the active interface of a FST STA AP common MAC MAC addr MAClog0 60GHz MAC 5 MAC 60 MAC_ad0 60GHz PHY 5 PHY 60 11ad STA PHY60 MAC 60 MAC addr: MAC_ad0 FST STA PHY 5 PHY 60 MAC 5 Physical MAC addr: MAC1 MAC 60 Physical MAC addr: MAC2 Logical MAC addr: MAClog0 IP IP addr linked to the unique logical MAC addr: MAClog0

How to perform the fast session transfer Trigger the switch by a signal frame (1/3) The trigger signal frame should provide the information to localize the destination band and to indicate which station the switch concerns FST signal frame needs to include The channel number from the destination channel The BSSID of the destination band The AID of the station that will switch band Slide 13

How to perform the fast session transfer Trigger the switch by a signal frame (2/3) Additional information in FST signal frame to speed up the FST Option 1: include the capabilities of the destination channel in the FST signal frame By doing this, the station does not need to wait for the next beacon once arrived in the destination band in order to get the capabilities This will be very efficient for destination bands/channels working with CSMA-CA (ex: from 802.11ad to 802.11n or 802.11ac): very low FST duration However, for TDMA-based destination bands/channels like 802.11ad 60 GHz, the station will anyway need to wait for the next beacon to be informed a) of the next contention-period to request a reserved slot b) of its reserved slot, if a slot has been pre-reserved Slide 14

How to perform the fast session transfer Trigger the switch by a signal frame (3/3) Additional information in FST signal frame to speed up the FST Option 2: use the principle of the "channel switch announcement frame" to plan the arrival in the destination band just before the beacon transmission signaling of the destination band/channel TBTT in the FST signal frame in addition, the switch can be planned using the "channel switch announcement element" field in the FST signal frame By doing this, the station will directly receive the capabilities and the contention-period time in case of TDMA. This will be very efficient for all destination band/channels working with either CSMA-CA or TDMA Slide 15

Fast session transfer performance Speed of the FST When using option 2, the FST switch time easily satisfies the 5 to 10 ms switching requirements FST duration only includes the time needed to perform the switch and the reception of the beacon on the destination band/channel Trigger of the FST by the AP Trigger by a FST signal frame Such a decision requires a report on one band/channel of particular metrics (such as the load and SNR) of the other band/channel Trigger of the FST by the station The FST can be instantaneous thanks to UL data transmission in the new band Slide 16

March 2010 doc.: IEEE 802.11-10/0xxxr0 May 2010 Conclusions Fast session transfer is a very important feature to improve home network by allowing the joint management of multiple bands, and to open new market opportunities. To be efficient, FST needs to be triggered by either one or the other device of a link and to be as fast as 5 to 10ms. We proposed to share the association parameters and a new trigger frame that enable such an efficient FST. Slide 17 Slide 17 Page 17 Yuichi Morioka, Sony Corporation

March 2010 doc.: IEEE 802.11-10/0xxxr0 May 2010 Straw polls Do you support inclusion of Fast Session Transfer, as described in 10/491r0 in the TGad draft amendment? Yes: No: Abstain: 2.4/5 assisted DLS of 60 GHz Slide 18 Page 18 Yuichi Morioka, Sony Corporation

Reference [1] “5-60 GHz use cases”, 802/11-09-0835r0 March 2010 doc.: IEEE 802.11-10/0xxxr0 May 2010 Reference [1] “5-60 GHz use cases”, 802/11-09-0835r0 [2] “Fast Session Transfer use cases”, 802/11-10-0134r0 [3] “Collaboration between 2.4/5 and 60GHz”, 802/11-10-0492r0 Slide 19 Page 19 Yuichi Morioka, Sony Corporation

How to perform the fast session transfer Trigger the switch by a signal frame Time TBTT signaled in FST signal frame Time FST signal frame FST switch duration << 5ms FST Switching instant Slide 20