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Sure, that fits what I had in mind. Any of
the low bit rate BT devices currently so prevalent.
(I've got a BT headset, mouse, and connection to my
PDA going on my PC right now with 802.11g).
Tnx.
-Ben
----- Original Message -----
Sent: Friday, June 27, 2008 9:21 AM
Subject: Re: 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 -----
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:
- Make sure that neither the
simulations nor the lab experiments use any form of collaborative
coexistence mechanism.
- 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
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.
----- 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.
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