May 2002

Terry Cole, AMD

Slide 1

doc.: IEEE 802.11-02/300R1

Submission

Slides to Assist with Joint Meeting of TgE and TgG

Terry ColeAMD Fellow

terry.cole@amd.com

+1 512 602 2454

May 2002

Terry Cole, AMD

Slide 2

doc.: IEEE 802.11-02/300R1

Submission

Introduction

• Slides to assist with moving through a number of issues

• Both 802.11e and 802.11g have the goal to complete comment resolution and return to ballot at this meeting.

May 2002

Terry Cole, AMD

Slide 3

doc.: IEEE 802.11-02/300R1

Submission

What needs coordinating? • Some boring stuff:

– Use of capability bits– Use of information elements– Order of information elements in management frames– Changes to SDL

• Some more intriguing stuff:– 802.11g operating models– 802.11e/g potential interactions

• aCWmin Times• Superframe structures• Contention Free Bursts

May 2002

Terry Cole, AMD

Slide 4

doc.: IEEE 802.11-02/300R1

Submission

Capability Bit Overloading • Approved bits (802.11a and 802.11d none)

– 802.11-1999 has b0 to b4 (ESS, IBSS, CF Pollable, CF Poll Request, Privacy)

– 802.11b added b5, b6, b7: (Short, PBCC, Channel Agility)

• Balloted bits (802.15.2 and 802.11f none)

– 802.11h proposes: b8 (Spectrum Management)– 802.11i proposes: b11 (Enhanced Security)– 802.11g proposes b8 and b9 (ER-PBCC, CCK-OFDM)– 802.11e proposes b8, b9, b10, b15 (qos, fec, bridge portal,

extended capability element)

• Observations– TgH, TgE, and TgG are all using b8!– 8 bits are available and 8 bits are being added!

May 2002

Terry Cole, AMD

Slide 5

doc.: IEEE 802.11-02/300R1

Submission

Capability Bit Overloading • We recommend coordination at this meeting,

– G and E should choose now, if possible making a solution that requires no more meetings.

• Mission Possible! • Propose to move forward with:

– 802.11h: b8 (Spectrum Management)– 802.11i : b11 (Enhanced Security)– 802.11g: b9 and b10 (ER-PBCC, CCK-OFDM)– 802.11e: b12, b13, b14, b15 (qos, fec, bridge portal,

extended capability element)

• Report in plenary

May 2002

Terry Cole, AMD

Slide 6

doc.: IEEE 802.11-02/300R1

Submission

Information Element Overloading • Approved elements (802.11a and 802.11b none)

– 802.11-1999 has 0-6, 16-31– 802.11d added 7-10

• Balloted element (802.11.f none)

– 802.11h proposes: 32-41– 802.11i proposes: 11-14– 802.15.2 proposes: 8– 802.11g proposes : TBD– 802.11e proposes 11-15, 32, 35

• Observations– 802.15.2 overlaps an already approved bit! Must change.– All other task groups overlap!

May 2002

Terry Cole, AMD

Slide 7

doc.: IEEE 802.11-02/300R1

Submission

Information Element Overloading • We recommend coordination at this meeting,

– G and E should choose now, if possible making a solution that requires no more meetings.

• Mission (almost) Possible! • Propose to move forward with:

– 802.11i keeps: 11-14– 802.11h keeps: 32-41– 802.15.2 is asked to take: 63– 802.11g takes: 43– 802.11e changes to: 44-50

• Report in plenary.

May 2002

Terry Cole, AMD

Slide 8

doc.: IEEE 802.11-02/300R1

Submission

Management Frame Orders• Approved orders (802.11a and 802.11b none)

– 802.11d expanded: beacon (11-13), probe request (3), probe response (10-12, 13+)

• Balloted orders– 802.11h proposes: beacon (14-18), association request (5-6),

reassociation request (6-7), probe response (13-17, 18+)– 802.11i proposes: beacon (7), association request (7), reassociation

request (8), probe response (7)– 802.15.2 proposes: beacon (11), probe response (11)– 802.11g proposes: beacon (11), probe response (10)– 802.11e proposes: beacon (14-15), association request (5-6), association

response (5-6), reassociation reqeust (6-7), reassociation response (5-6), probe request (3)

May 2002

Terry Cole, AMD

Slide 9

doc.: IEEE 802.11-02/300R1

Submission

Management Frame Orders• Observations

– 802.11i, 802.11g, and 802.15.2 overlap approved orders

– 802.11h and 802.11e proposals overlap

• We recommend coordination at this meeting, – G and E should choose now, if possible making a

solution that requires no more meetings. • Mission impossible!

– But we can make recommendations…

May 2002

Terry Cole, AMD

Slide 10

doc.: IEEE 802.11-02/300R1

Submission

Management Frame Orders • Propose to move forward with:

– 802.11h keeps things as is– 802.11i has to fix overlap with existing but keeps others as is:

• Beacon (add 19), probe response (add 18, 19+ for requested items)

– 802.15.2 is asked to change to fix overlap with existing:• Beacon (add 20), probe response (add 19, 20+ for requested items)

– 802.11g changes to avoid overlaps with existing:• Beacon (add 21), probe response (add 20, 21+ for requested items)

– 802.11e changes to: • beacon (add 22-23), association request (add 7-8), association response (5-

6), reassociation request (add 8-9), reassociation response (5-6), probe request (add 21, 22+ for requested items)

• Report in plenary.

May 2002

Terry Cole, AMD

Slide 11

doc.: IEEE 802.11-02/300R1

Submission

Updating SDL • The 802.11 group appointed a special task

group to make recommendations on SDL. That group has agreed to recommend that each task group:– Delete all SDL from the base document Annex C in

each new supplement– Include only such state diagrams that are useful to

understanding the document

• Propose that 802.11g and 802.11e both support and implement this!

May 2002

Terry Cole, AMD

Slide 12

doc.: IEEE 802.11-02/300R1

Submission

802.11g Operating Model • 802.11g is providing an extended rate PHY in the 2.4GHz

space• After much debate () the group is proceeding rapidly

with this operating model:• Extended Rate PHY (ERP) shall:

– Operate using CCK header and existing 802.11b signal field identifiers

– AND operate using OFDM preambles and modulation• Either in an all 802.11g mode• Or in a mixed environment where OFDM is not allowed without first

setting the NAV of other devices in the network• Uses aCWmin = 15 slot times to shift most of network benefit of 802.11g

to throughput of 802.11g STAs themselves

May 2002

Terry Cole, AMD

Slide 13

doc.: IEEE 802.11-02/300R1

Submission

802.11g Operating Model (2)• ER Phy may also:

– Operating using CCK header with unique signal field identifier followed by an embedded OFDM modulation (CCK-OFDM)

– Operate using CCK header with unique signal field identifier followed by embedded PBCC modulation (ER-PBCC)

May 2002

Terry Cole, AMD

Slide 14

doc.: IEEE 802.11-02/300R1

Submission

802.11g Operating Model (3)• Important Ramifications of mandatory operation model:

– The beacons contain information about whether the environment is mixed (802.11g+802.11b) or 802.11g exclusive (extended rates required).

– 802.11b stations generally will not sense the OFDM transmissions.

– In a mixed environment, it is very important to set the NAV of all stations (addressing hidden node issue) prior to sending OFDM transmissions.• For example, use RTS/CTS

– In a 802.11g exclusive environment, no protection mechanism is required

May 2002

Terry Cole, AMD

Slide 15

doc.: IEEE 802.11-02/300R1

Submission

802.11g Operating Model (4)• Important ramifications of optional operation

model:– Protection mechanism is not required– In a mixed environment, 802.11b stations will not be

able to decode the frames but can sense their presence via their CCK preamble and energy.

May 2002

Terry Cole, AMD

Slide 16

doc.: IEEE 802.11-02/300R1

Submission

802.11g Proposals• Additional topics are being discussed as means

to optimize mixed mode environments based on the 802.11-1999 base document:– Using the CFP mechanism, divide the time between

beacons in a OFDM only contention period and a common (802.11b and 802.11g) contention period

– Use RTS/CTS to set the NAV of all stations to allow OFDM transmission of more than one data/ACK pair… time not to exceed max time of packet transmission at 11Mbps.

May 2002

Terry Cole, AMD

Slide 17

doc.: IEEE 802.11-02/300R1

Submission

aCWmin Times• The current mixed network model of 802.11g uses two

aCWmin times– 802.11b stations use 31 slot times

– 802.11g stations transmitting OFDM sequences use 15 slot times

– 802.11e has proposals to modify aCWmin from the PHY base time to account for higher and lower priority flows

• How will this be described to function with 802.11g?• How will this method work in a mixed

802.11g/802.11b environment?

May 2002

Terry Cole, AMD

Slide 18

doc.: IEEE 802.11-02/300R1

Submission

Superframes• Currently, 802.11g maintains the superframe structure loosely

implied by the base 802.11-1999 document– Approximately uniformly spaced beacons– Some beacons followed by a contention free period used for polling

by the AP

• We have a proposal (02/301) to modify this:– A CCK beacons followed by a contention free announcement,

immediately followed by an OFDM CF-END.– So some beacons are really followed by a OFDM only contention

period, set apart form the normal common (802.11b and 802.11g) contention period

• How will the proposed 802.11e superframes be described to function with this 802.11g proposal?

May 2002

Terry Cole, AMD

Slide 19

doc.: IEEE 802.11-02/300R1

Submission

Contention Free Bursts• Currently, 802.11g maintains the transactions listed in

Table 20 by the base 802.11-1999 document• We have a proposal (02/301) to modify this:

– RTS/CTS would set the NAV of all devices– The requester could send multiple frames without contention

to the same responder but not going past the NAV expiration– In the event of an ACK time-out, the requester could

retransmit without contention but not going past the NAV expiration.

• How will the proposed 802.11e contention free bursts be described to function with this 802.11g proposal?