Transcript · Reviewed the Goal of April meeting

March 2013
doc.: IEEE 802.11-13/0292r0
Backward compatibility of 11aj with 11ad
Date: 2013-03-17
Authors:
Name
Affiliations
Carlos Cordeiro
Intel Corp.
[email protected]
Brian Hart
Cisco
[email protected]
Sai Shankar
Tensorcom
[email protected]
Payam Torab
Broadcom
[email protected]
Chao-Chun Wang
MediaTek
[email protected]
Kazu Takahashi
Panasonic
[email protected]
Gal Basson
Wilocity
[email protected]
Su-Khiong Yong
Marvell
[email protected]
Brad Lynch
Peraso
[email protected]
Submission
Address
Slide 1
Phone Email
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
Purpose
• This presentation tackles the requirement of backward
compatibility of 11aj with 11ad devices in the 60 GHz
band
– An 11aj PAR requirement
– Only way to prevent thrashing of the 60 GHz band with
incompatible devices
• Backward compatibility has proven to be key to the
success of 802.11n/g/a and it will not be different for 11aj
• Here we revisit the principle of backward compatibility
and bring up a proposal on how this can be
accomplished by 11aj
Submission
Slide 2
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
The principle of backward compatibility
• The 11aj PAR states: “The amendment shall maintain
backward compatibility with 802.11ad when it operates in
the 59-64 GHz frequency band.”
• The principle of backward interoperability is well
established in 11ac/n/a/g/b
– Legacy STAs do not interfere with frame exchanges using nextgen PPDUs between next-gen STAs, and next-gen STAs do not
interfere with frame exchanges using legacy PPDUs between
legacy STAs. As a result, legacy and/or next-gen STAs are
allowed to coexist with each other.
• This same principle should apply to 11aj!
Submission
Slide 3
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
References from 802.11-2012
• From 9.23.1 within (9.23 Protection mechanisms):
“These protection mechanisms cause a STA that is a
potential interferer to defer any transmission for a known
period of time. When these mechanisms are used, non-ERP
STAs do not interfere with frame exchanges using ERP
PPDUs between ERP STAs and non-HT STAs do not
interfere with frame exchanges using HT PPDUs between
HT STAs. As a result, non-ERP and/or non-HT STAs are
allowed to coexist with ERP and/or HT STAs.”
• See also (9.7 Multirate support)
Submission
Slide 4
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
Comments on 11/13-0175r0
• In slide 6 of 11/13-0175r0, 3 coexistence “modes” of 802.11n are
presumed, labeled: Legacy mode, Mixed mode and Greenfield mode
• Then, the following proposal is made based on the authors’
understanding of the 11n Greenfield mode:
– “Exclusive Mode
–
No backward compatibility to 802.11ad device”
• This is a misunderstanding:
– 11n does not have modes: 11n has PHY formats (legacy, HT-MM, HT-GF)
with associated usage rules to ensure backwards compatibility
– Greenfield “mode” does NOT imply that there is no backward compatibility
– Greenfield allows data transmissions in a BSS to be restricted to a given
mode (e.g., HT), but backward compatibility still exists
• Use of HT-GF format is subject to an array of restrictions to minimize backwards
compatibility issues. E.g., review the HT Protection, Nongreenfield HT STAs
Present and OBSS Non-HT STAs Present fields in the HT Operation element, and
associated normative text
Submission
Slide 5
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
Applying the principle of backward
compatibility to 11aj: a proposal
•
•
Mechanisms must be defined to ensure that 11aj is backward compatible
with 11ad
Some proposed mechanisms:
– Support of 11ad MCS0, which is used to transmit several basic frames (see 9.7)
– 11aj STAs shall follow the same frame transmissions rules during the BTI, A-BFT
and ATI portions of the beacon interval that are applicable to DMG STAs
– During the DTI, 11aj stations may use 11aj specific modes after ensuring
appropriate protection (e.g., similar to HT-GF protection rules in 802.11n)
Beacon Interval
BTI
•
A-BFT
ATI
DTI
BTI
Additional mechanisms might still be needed to meet the backward
compatibility requirement of the 11aj PAR
Submission
Slide 6
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
Under this proposal (slide 6), how could
11aj STAs use 11aj specific modes?
• There are possibly several alternatives for 11aj STAs to
use 11aj specific modes during the DTI
• For example, to support the smaller BW channel
desired by 11aj, possible extensions can include:
– Extending the Extended Schedule element to signal the channel
BW
– Extending the RTS/DMG CTS frames to signal the channel BW
(e.g., transmitting DMG CTS-to-self)
– Extending the frames used during the SLS to also signal the
channel BW
– Other?
Submission
Slide 7
Multiple co-authors
March 2013
doc.: IEEE 802.11-13/0292r0
Summary
• Backward compatibility of 11aj with 11ad is critical not
only because it is in the 11aj PAR, but also because it:
– Ensures equitable and fair use of the 60 GHz band
– Leverages all the implementation efforts made into 11ad
– Increases the chances of 11aj success in the marketplace
• We propose that 11aj follows the same principle of
backward compatibility that is incorporated in other
.11 amendments
• The backward compatibility proposal made in this
presentation follows this principle
Submission
Slide 8
Multiple co-authors