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Re: [802.19] 40MHz 802.11n Bluetooth Sim Pamameters

It would also be useful to consider Bluetooth mice and keyboards as well.  I was at a standards meeting this week and someone told me that they could see 15 Bluetooth mice when they scanned for theirs.

Bill

On Fri, Jun 27, 2008 at 6:09 PM, Benjamin A. Rolfe <ben@xxxxxxxxxxxxxx> wrote:
Very good points, Ed, 
I wasn't thinking broadly enough: In my case I was thinking about a single user with multiple devices, but it is very realistic (and more typical) that you have two users sitting at the same table, two PCs, two headsets, etc.  Many times you see two people sharing a table at the coffee shop with the PCs back-to-back, thus the antenna separated by a few inches but without out-of-band signaling available to coordinate.  One (or both) user is streaming video from his HD video cam to his PC, for example, using a lot of bps.  Perhaps they are sharing content. The point is doing more than internet access.
 
Another question: Can we "dial back" BW usage in a similar way that we can use transmit power control to reduce the spectral footprint to only as big as we need? Having read through the 802.11n draft sections on 40MHz mode (thanks for the right section # references BTW), I am still a bit confused as to how selection can happen.   Can we mix 20MHz and 40MHz nodes at the same time?  If the added BW is not needed for data rate or link margin, will a node drop back to 20 MHz?   Using transmit power control to tune the link has proven to be a good thing for spectral effectiveness and coexistence, and it seems to me the same idea applied to BW management might be useful as well.  Is this possible with the current 'n' ?  I'm not so sure it will help, mind you. Potentially with the wider BW you would need lower power to get the same link margin, also reduces the effective SoI. Surely someone has run these trade-offs?  The results would be interesting (and relent to a coexistence discussion!).

Thanks
-B
----- Original Message -----
From: Reuss, Ed
Sent: Friday, June 27, 2008 8:13 AM
Subject: RE: 40MHz 802.11n Bluetooth Sim Pamameters

Hi Steve, Ben:

 

These are nice use cases with one caveat. If the PC contains both the BT radio and the 802.11n radio, then I would expect that most manufacturers would implement one of the 2, 3 or 4 wire "Coexistence Bus" mechanisms that are available for many BT, Wi-Fi and BT/Wi-Fi combo products available today. These collaborative coexistence methods will work just as well for 40 MHz transmissions as well as for 20 MHz transmissions.

 

So we have two alternatives:

  1. Make sure that neither the simulations nor the lab experiments use any form of collaborative coexistence mechanism.
  2. Modify the use case so that the user is watching streaming videos via their PC while talking on the cell phone with a headset, under the assumption that there will be no form of collaboration between the PC and the cell phone or the PC and the headset.

 

Either is acceptable to me.

 

-- Ed Reuss

 

 

Ben,

 

            If you would like to make modifications to the version I just sent out that Vinko edited, feel free.  We can discuss the various edits in Denver.

 

Regards,

Steve

 

From: Benjamin A. Rolfe [mailto:ben@xxxxxxxxxxxxxx]
Sent: Wednesday, June 18, 2008 3:17 PM
To: Shellhammer, Steve; ppiggin@xxxxxxxxxxxx; mjlynch@xxxxxxxxxx; Mark.austin@xxxxxxxxxxxx; stds-802-19@xxxxxxxx; nada.golmie@xxxxxxxx; eldad.perahia@xxxxxxxxx; Joseph.Levy@xxxxxxxxxxxxxxxx; bheile@xxxxxxxx; john.barr@xxxxxxxxxxxx; swhitesell@xxxxxxxx; necati.canpolat@xxxxxxxxx; I_reede@xxxxxxxxxxxx; carl.stevenson@xxxxxxxx; Matt.Smith@xxxxxxxxxxx; vivek.g.gupta@xxxxxxxxx; bkraemer@xxxxxxxxxxx; Jones, Vk; bill.shvodian@xxxxxxxx; david.cypher@xxxxxxxx; sli@xxxxxxxxxx
Cc: Reuss, Ed
Subject: Re: 40MHz 802.11n Bluetooth Sim Pamameters

 

A couple questions for the group:

- I think it would be a good idea to add usage models:

1. The VoIP via the internet model. The user has a BT headset, using a laptop PC to Skype over the internet, while at the same time (in user time frame) browsing the web, transferring files and so on.  In this  scenario the STA is much closer to one end of the BT link (10cm or less).  Since I know this can be done with 11g and BT without one saturating the other, I feel this is a realistic scenario for 11n - make sense?

 

2. Streaming video and BT sound: The user is streaming video to his personal media device and listening via a hifi stereo BT headset.   Same thing - two ends of the 11n and BT links are very close.

 

- would it make sense to have a less than full duty cycle scenario for 11n.  For the "internet user" scenario, I suspect the 11n duty cycle would be quite a bit less than the maximum, because of the backbone access bottle nck. So if I assume a bottle neck of 6Mbps what would be a reasonable duty cycle?

 

- For the 11n guys: with maximum payload transfer rate, what is the effective on-air duty cycle for 11n at full speed (considering necessary IFSes, average back-offs, etc.)?  What would be reasonable for the 6Mbps bottle neck scenario?

 

- For the BT guys, what is expected on-air duty cycle for Bluetooth (a) normal voice and (b) HiFi sound?

 

If I get some input, I can write up the scenarios.

-Ben

 

 

----- Original Message -----

Sent: Wednesday, June 18, 2008 12:57 PM

Subject: 40MHz 802.11n Bluetooth Sim Pamameters

 

On the Monday conference call I volunteer to begin a simple Simulation Parameters document for evaluating the impact of 40 MHz 802.11n on Bluetooth.  I have posted a first version of that document on the server at,

 

 

If anyone wants to make any modifications or additions you can add your name to the list of authors and revise the document.  Hopefully we can agree on this simple document via email.  If someone feels we need a conference call before the Denver meeting to discuss this please notify me.

 

Thanks,

Steve

 





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