Comment resolution #79

1. Comment resolution #79 Authors: Date: 2009, November 17 Graham Smith, DSP Group

2. Abstract • Comment 79 (Joe Epstein) opened up a discussion on Off Channel Operation and possible restrictions with respect to Enterprise networks. This submission is to clarify the situation for residential networks. Graham Smith, DSP Group

3. Comment CID 79 – “Channel switch messages allow the TDLS stations to circumvent admission control requirements on channels with only AC-mandatory APs, by associating one another channel and then switching to it. The draft's authors do recognize the problem when TDLS clients remain on the same channel, but the same consideration should be given to other channels. In fact, a more general problem is that TDLS clients can occupy channels by their own volition that are in conflict with well-managed large-scale networks” Graham Smith, DSP Group

4. Points arising from Comment If STAs choose to go ‘off channel’, then the following points would appear to be relevant • They should be moving for ‘good’ reasons • Better bandwidth is probably #1 reason • 2.4 and 5GHz operation is related to this • 11n • They should not cause the new channel to become potentially congested - not good for them, not good for others • Is there an AP already there? • Is it a QAP? • Are there ACM bits set? • Is HCCA present? • How much traffic already? • Basically, it has been assumed that the STAs would go to an unused channel – suggest we should encourage this? Graham Smith, DSP Group

5. Enterprise/Residential • Enterprise is managed network(s) so some form of control seems to be useful. • It was proposed to add “No Off-Channel Operation” bit to AP • Could add other restrictions if enterprise experts desire • My concern is for Residential Networks • Big effort in 11aa to improve OBSS in residential, would like to discourage TDLS from making it worse – could wax lyrically on this for some time…but… • Suggest that wording is added that, at the least, suggests or recommends certain behavior when implementing “Off-Channel operation” Graham Smith, DSP Group

6. Proposed Text (11.19.4.1) Off-Channel Operation “It is recommended that in general TDLS STAs propose target channels that have no detectable beacons or traffic. If no such channel is available, then it is recommended that the TDLS STA propose a target channel where beacons are detected but with little or no detectable traffic. It is further recommended that TDLS STAs do not propose a target channel where the presence of beacons indicate that ACM bits are set, unless little or no traffic is detected.” Thought: Could consider deleting the last sentence but this does address the comment more directly so recommend leaving it in. Graham Smith, DSP Group

7. Proposed Text (11.19.4.1) Off-Channel Operation “It is recommended that in general TDLS STAs propose target channels that have no detectable medium occupancy. If no such channel is available, then it is recommended that the TDLS STA propose a target channel where beacons are detected but with little or no additional medium occupancy. It is further recommended that TDLS STAs do not propose a target channel where the presence of beacons indicate that ACM bits are set, unless little or no additional medium occupancy is detected.” Thought: Could consider deleting the last sentence but this does address the comment more directly so recommend leaving it in. Graham Smith, DSP Group