1. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 1 Issues With Off-channel TDLS Date: 2008-03-05 Authors:

2. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 2 Abstract Issues with off-channel Tunneled Direct Link (TDL) are presented for study group discussion

3. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 3 Is Off-Channel TDL in scope? From item 5.2 Scope: –This amendment defines a new Direct Link Setup (DLS) mechanism to allow operation with non-DLS capable access points and allow stations with an active DLS session to enter power save mode. The scope is specifically limited to modifications related to the DLS mechanism. Off-channel operation does not contribute to the solution that allows DLS operations with legacy access points nor it helps enabling power save modes, therefore: –It seems like off-channel TDL is outside the scope of current TGz PAR

4. doc.: IEEE 802.11-08/309r0 Submission How useful is off-channel TDL? The common view on usefulness of off-channel TDL: –The purpose of going off-channel is to take traffic out of a congested network and move it to an empty channel –The traffic needs to be exchanged somewhere, and it is better to do so on an empty channel than on a busy channel However, –With limited unlicensed spectra available, the term empty channel becomes less and less practical. Even relatively under- utilized channel can become heavily used in the next instance with new load, or with new networks settling on it –Therefore, issues of coexistence, fairness in media access, effective spectrum sharing are becoming more important –The need for new bandwidth shall promote more effective utilization, (using new technologies, for example) 2/8/2014 Michael Livshitz, MetalinkSlide 4

5. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 5 Problems with off-channel TDL Off-channel DLS traffic may use significant amount of shared bandwidth without participating in network coexistence –STAs [participating in off-channel TDL] will not advertise their capabilities and policies (no beaconing). –STAs will not respond to probe requests –STAs will not respond to any 11k management frames This makes other networks unaware of what is going on and impedes their decision in allocating and using shared resource

6. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 6 Examples of potential problems Voice/Video network with ACM policies –Note that the problem is different from OBSS problem, since OBSS can be detected, managed and avoided Negative impact on QoS enabled WLANs WLANs with 11k radio resource management 802.11n 20/40 coexistence mechanism –Off-channel is not detected, not avoided, resulting in mutual collision. Draft 802.11n 20/40 coexistence algorithm specifically addresses legacy OBSS Intelligent channel selection for multimedia networks –AP scanning for better channels, STAs scanning for OBSSs are not capable of DLS traffic detection

7. doc.: IEEE 802.11-08/309r0 Submission Moving forward options Option 1 –Do nothing. Resolve possible no-votes in comment resolution phase Option 2 –Consider modifying PAR to include off-channel TDL support, and –Consider developing appropriate coexistence mechanisms, like Scanning before going off-channel Adding limited beaconing Switching back on OBSS detection Option 3 –Consider removing off-channel TDL from TGz draft specification Other options? 2/8/2014 Michael Livshitz, MetalinkSlide 7

8. doc.: IEEE 802.11-08/309r0 Submission Discussion and Straw Poll(s) 2/8/2014 Michael Livshitz, MetalinkSlide 8

9. doc.: IEEE 802.11-08/309r0 Submission 2/8/2014 Michael Livshitz, MetalinkSlide 9 References Draft IEEE P802.11z/D0.2, January 2008 (Draft Amendment to IEEE Std 802.11) P802.11z PAR –http://standards.ieee.org/board/nes/projects/802-11z.pdfhttp://standards.ieee.org/board/nes/projects/802-11z.pdf