1. Greenfield protection mechanism
September 2006
doc.: IEEE /1458r0
September 2006
Greenfield protection mechanism
Date:
Authors:
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Douglas, B., et al.
Joonsuk Kim, Broadcom Corp.

2. September 2006
doc.: IEEE /1458r0
September 2006
Abstract
The current Greenfield protection mechanism given in clause does not adequately address the issue of collisions between Greenfield and non-Greenfield devices. To ensure proper interoperability with 11a/b/g devices, we propose changes to the current text to minimize the probability of collision between GF devices and non-GF devices.
This presentation addresses the following letter ballot comments:
CID 118, 4017, 4035, 4511, 4522, 10292, 12030, 12048, 12127, 12049
Douglas, B., et al.
Joonsuk Kim, Broadcom Corp.

3. Current Greenfield protection is not adequate
September 2006
Current Greenfield protection is not adequate
There are over 500 million legacy a/b/g devices that cannot receive Greenfield transmissions, and never will. These devices will collide with GF mode transmissions in the 2.4 and 5 GHz bands. These collisions will degrade the QOS of voice and video traffic carried over legacy a/b/g devices and voice and video traffic carried over n GF and mixed-mode devices.
We must introduce strong mechanisms to minimize the probability of collisions between GF and non-GF devices.
Although a protection is said to be required in the current text (below), no protection method is specified. The protection used is left up to the implementers.
Douglas, B., et al.

4. Current Greenfield Protection Text
September 2006
Current Greenfield Protection Text
Douglas, B., et al.

5. Proposed changes to text (1)
September 2006
Proposed changes to text (1)
Greenfield protection
If there are one or more non-HT STA or one or more non-Greenfield STA associated to an HT AP, that HT AP shall set the Non-GF Devices Present bit in the Additional HT IE frame to 1. If an HT AP is not capable of receiving Greenfield transmissions, that HT AP shall set the Non-GF Devices Present bit in the Additional HT IE frame to 1. The HT AP must advertise the presence of devices not capable of receiving Greenfield transmissions in its probe responses and in its beacon transmissions.  Every n AP or STA that detects the Non-GF Devices Present bit set in a received beacon,  shall not use Greenfield mode for transmission.
Douglas, B., et al.

6. Proposed changes to text (2)
September 2006
Proposed changes to text (2)
HT Information element
Table n21 – HT Information Element
Non-Greenfield Devices Present
Indicates if any STAs that are not capable of receiving Greenfield transmissions have associated, or indicates that the AP itself is not capable of receiving Greenfield transmissions. Present in Beacon and Probe response frames transmitted by an AP. See
Set to 0 if the AP and all STAs that are associated to the AP are capable of receiving Greenfield transmissions.
Set to 1 if the AP or one or more associated STAs are not capable of receiving
Greenfield transmissions.
Douglas, B., et al.

7. Proposed changes to resolutions
September 2006
Proposed changes to resolutions
CIDs 118, 4017, 4035, 4511, 12127: R C
CIDs 12030, 12048, 10292, 12049: R A
CID 4522: C
Douglas, B., et al.

8. Straw Poll Would You support the proposed changes to the text?
September 2006
Straw Poll
Would You support the proposed changes to the text?
Douglas, B., et al.

9. September 2006
Feedback
What modifications would you suggest to improve what is being proposed by this submission?
Douglas, B., et al.