[STDS-802-11] Call for coexistence studies

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G’day all,

Note: this e-mail Is relevant to the operation of 802.11ax in 6Ghz band and so should be of interest to participants of TGax

The IEEE 802.11 Coexistence SC (and its predecessor, the IEEE 802.11 PD/ED ad hoc) has been doing an excellent job over the few years considering and dealing with issues of coexistence between 802.11 (based on both legacy 802.11a/n/ac and future 802.11ax) and other technologies (mostly the unlicensed LTE technologies) in the 5GHz band.

The IEEE 802.11 WG recently approved and sent two Liaison Statements to ETSI BRAN (most recent LS attached) supporting a revision to the European harmonised standard (EN 301 803) for the 5GHz band that would allow any technology (including 802.11ax) to use either:

· The traditional 802.11 PD/ED mechanism and thresholds (-82 dBm and -62 dBm respectively)

· A ED-only mechanism using a threshold of -72 dBm (or higher with a lower tx power).

However, discussions are beginning to transition from coexistence in the legacy 5GHz band (legacy in the sense they contain a large number of existing Wi-Fi deployments) to coexistence in the greenfield 6GHz band (greenfield in the sense it currently contains few/no Wi-Fi or unlicensed LTE deployments). The greenfield nature of 6GHz means that we can more easily consider different coexistence mechanisms and thresholds.

Indeed, a variety of suggestions have been made for mechanisms that are claimed to support fair and efficient coexistence between 802.11 and other technologies in the 6Ghz band, including:

· Status quo: use the 5GHz rules (from refined EN 301 893) in 6Ghz band

· ED-only: all technologies use ED-only (ie no use of PD)

o Thresholds suggested include -72dBm, -62dB or even -52dBm

· Common preamble: all technologies use the traditional 802.11 mechanism and thresholds using a common preamble

o Could be either 802.11a preamble or a new preamble

o Note: the use of the 802.11a preamble is likely to unpopular in 3GPP, and previously 802.11 chip vendors indicated it was too late for them to consider a new preamble in 6GHz

· Alt 4: any technology that detects its own preamble at -82 dBm can use an ED of -62 dBm, otherwise a an ED of -72 dBm

o Note: this means that LAA would only defer to 802.11 at ED of -62dBm

o Note: IEEE 802.11 WG’s LS to ETSI BRAN noted that 3GPP simulations have already demonstrated this approach is unfair to 802.11 systems using the traditional mechanism and thresholds

Call for action: I would ask that anyone who has studies that support any of these options, or that show any of these options are unacceptable, to make them available for consideration by the IEEE 802.11 Coexistence SC in July or Sept or at the proposed 802.11/3GPP Coexistence Workshop. Studies could be based on analysis, old or new simulations or actual deployment measurements. If you think you might be able to contribute such a study, please ping me as soon as possible so I can plan upcoming agendas.

Andrew Myles

Chair of IEEE 802.11 Coexistence SC

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