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Re: [802.15_GENERAL] TGn Letter Ballot Support

Title: Re: [802.15_GENERAL] TGn Letter Ballot Support
 
John,
 
If the lack of ability of one technology deployed in the 2.4 GHz band to directly communicate with a different technology also deployed in the 2.4 GHz band is a definition of a broken standard, then TGn is not the only broken standard.
 
It is clear that an 802.15 device cannot transmit an 802.11 frame, just as an 802.11 device cannot transmit an 802.15 frame. Each of these devices must do what it can on its own to share spectrum. 802.15 includes the concept of AFS as a means to attempt to better coexist with 802.11 devices. AFS relies on the ability of an 802.15 device to make its own determination as to when to restrict its spectrum usage. 802.11 devices cannot send a message to the 802.15 requesting them to use AFS.
 
Similarly, 802.11 TGn devices are being provided with a mechanism that they can employ to facilitate spectrum sharing. The 802.11 mechanism allows any device that is capable of transmitting an 802.11 formatted and modulated frame to specifically prohibit the use of 40 MHz transmissions. Many 802.15 devices are being shipped to today with a co-located 802.11 device, and the expectation is that many more such products will be shipped in the future. Such devices can easily be programmed to prohibit all 40 MHz transmissions within range of the 802.11 transceiver. Other 802.11-transceiver-equipped devices that are aware of non-co-located 802.15 devices can also send such a frame.
 
The information that you received from an Atheros person regarding the ability of a current 802.11 device to signal to TGn devices to NOT use 40 MHz is INCORRECT. A legacy device can include the new 20/40 BSS Coexistence element in Beacons and/or Probe Request and Probe Response frames. It is this new element that contains the 40 MHz Intolerant bit. There is no restriction as to which options need to be implemented in determining if a STA or AP may send this element. Existing devices are allowed to send this element and certainly, to set the 40 MHz Intolerant bit to prohibit 40 MHz transmissions. See the changes in the TGn draft to the Beacon and other frame formats. Here is an example:
 
 
7.2.3.1 Beacon frame format
 
Table 7-8
 
20/40 BSS Coexistence  The 20/40 BSS Coexistence element may appear in this frame.
 
 
Note that lack of qualifiers regarding the inclusion of the element in this frame.
 
 
There is also a management action frame that can be used to send this information.
It can be broadcast and it can be sent with a specific unicast MAC address to allow for explicit acknowledgement of receipt. It can be sent from a device that is not a member of the BSS and still must be obeyed.
 
 

Matthew Fischer
Nice Guy
408 543 3370 office
650 796 9206 mobile
mfischer@broadcom.com

 

From: John Barr [mailto:john.barr@MOTOROLA.COM]
Sent: Tuesday, May 27, 2008 6:22 AM
To: STDS-802-WPAN@LISTSERV.IEEE.ORG
Subject: Re: [802.15_GENERAL] TGn Letter Ballot Support

Matthew,

Thanks for your opinion.

Can you explain exactly how an 802.15 device can “signal the 40 MHz TGn devices”? I have gone through the current draft and don’t really see where this is clearly defined. I also asked someone from Atheros about how a current 802.11 device can signal the 40 MHz TGn devices and his response was that they can’t but 40 MHz devices who see non-TGn beacons should note this and prevent use of 40 MHz channels, but I can’t find that either.

Allowing 40 MHz operation with a broken coexistence mechanism seems to be worse than specifically not allowing 40 MHz operation with a shall in the standard. If someone decides to use 40 MHz channels, those that are affected may be able to withdraw their rights to any IP because the LOA only says you need to provide RAND licensing when the implementation conforms to the standard. Conforming with a broken coexistence mechanism seems to be a worse situation.

Regards, John


On 5/23/08 9:29 PM, "Matthew Fischer" <mfischer@broadcom.com> wrote:

I will be voting YES on TGn LB129, and I would urge others who are interested in defending 802.15.x devices' access to the ISMii band to vote YES as well.

The current draft of the 802.11 TGn amendment contains normative language describing a mechanism (i.e. the 40 MHz Intolerant bit) that allows non-related devices to signal to the 40 MHz TGn devices that they cannot send 40 MHz transmissions, effectively allowing other users of the ISMii band to restrict the use of 40 MHz transmissions by TGn devices. 40 MHz 802.11 TGn devices are required to obey this signaling whenever it occurs.

If 40 MHz operation is forbidden in ISMii by 802.11 TGn, then 40 MHz operation will be implemented as a set of vendor-specific non-standardized modes with variable degrees of good citizenship regarding spectrum sharing and with little or no opportunity for such devices to be controled by other users of the ISMii band.

For these reasons, it is in the best interest of 802.15.x technology providers and other users of the ISMii band to vote YES on the TGn-standardized mode of 40 MHz operation that includes specific requirements to force TGn devices to cease 40 MHz operation when requested.

 
Matthew Fischer
Nice Guy
+1 408 543 3370 office
+1 650 796 9206 mobile
mfischer@broadcom.com <mailto:mfischer@broadcom.com>

 

 
From: John Barr  [mailto:john.barr@MOTOROLA.COM]
Sent: Friday, May 23, 2008 8:36  AM
To: STDS-802-WPAN@LISTSERV.IEEE.ORG
Subject:  [802.15_GENERAL] TGn Letter Ballot Support

 
As mentioned in Jacksonville, the current draft of TGn  includes use of 40 MHz channels in 2.4 GHz spectrum. This will significantly  impair ability of other IEEE standards using 2.4 GHz spectrum to coexist with  TGn devices running at 40 MHz. Even though the rejection of my comment number  6069 states that there is provision for coexistence with other radio systems  using 2.4 GHz spectrum, the actual text for this is informative and does not  actually include tests for IEEE 802.15.1 nor IEEE 802.15.4 devices. See  attached note to TGn I sent during the Jacksonville meeting. At the one  session where there was any discussion on my comment, I spoke against the  resolution and no one spoke for the resolution rejecting my suggested change  (not to allow any use of 40 MHz channels in 2.4 GHz spectrum). (See  attached)

As it current stands there is no clear method to prevent use  of 40 MHz channels in 2.4 GHz when IEEE 802.15.1 and 802.15.4 devices are  operating in the same spectrum.

You can vote against the current TGn  letter ballot by referencing my comment (6069) that is unresolved (not  accepted by the submitter) and requesting the same resolution:  In  20.3.15 change "When using 40 MHz channels, it can operate in the channels  defined in 20.3.15.1 and 20.3.15.2." to "When using 40 MHz channels, it can  only operate in the channels defined in 20.3.15.2."

James Gilb may be  able to clarify just how to vote on this. Voters who previously approved the  original LB can change their vote to disapprove based on this  comment.

Thank you for your support.

Regards,  John
--  
John R. Barr (John.Barr@Motorola.com)  
Director, Standards Realization - <http://www.motorola.com>
Vice  Chairman of the Board, Bluetooth SIG - <http://www.bluetooth.org>
(847)  576-8706 (office) +1-847-962-5407 (mobile) (847) 576-6758 (FAX)




--  
John R. Barr (John.Barr@Motorola.com)
Director, Standards Realization - <http://www.motorola.com>
Vice Chairman of the Board, Bluetooth SIG - <http://www.bluetooth.org>
(847) 576-8706 (office) +1-847-962-5407 (mobile) (847) 576-6758 (FAX)