TPC Overview of Joint Proposal

1. TPC Overview of Joint Proposal S. Choi1, Peter Ecclesine4, S. Gray2, C. Hansen5,M. Kasslin2, J. Kim5, S. Mangold3, Andrew Myles4,David Skellern4 and A. Soomro1 Philips Research1, Nokia Research Center2, ComNets Aachen University3, Cisco4 and Broadcom5 Aachen Uni, Broadcom, Cisco, Nokia & Philips

2. The TPC draft text’s primary goal is to satisfy regulatory requirements • Primary goal - must be satisfied • To satisfy the regulators • e.g. the average transmit power mitigation requirements specified by ERC documents • Secondary goals – “nice to have” • To define frame formats, information elements and mechanisms that enable additional functionality including: • Interference minimisation • Power consumption reduction • Range control • Link robustness Primary goal Aachen Uni, Broadcom, Cisco, Nokia & Philips

3. TPC procedures: TPC defines procedures that enable the selection of transmit powers within regulatory and local constraints TPC defines support procedures that may assist the operation of any autonomous transmit power selection algorithms TPC infrastructure elements: Country information element from 802.11d is used to communicate a BSS’s or IBSS’s regulatory maximum transmit power constraint Power Constraint information element is used to communicate the local maximum transmit power constraint Power Capability information element is used to communicate an STA’s transmit power capability to an AP Capability information fixed field contains a new bit indicating TPC capability A hidden station frame and element contains information relating to a potential hidden station notification or reply The TPC draft text defines a variety of new infrastructure elements and procedures Mainly supports primary goal Supports secondary goals – but needs to be standardised to ensure interoperability Summary of procedures & infrastructure Aachen Uni, Broadcom, Cisco, Nokia & Philips

4. TPC Overview of Joint Proposal Infrastructure Aachen Uni, Broadcom, Cisco, Nokia & Philips

5. Country information element from 802.11d is used to communicate a BSS’s or IBSS’s regulatory maximum transmit power constraint One octet One octet Element ID Length • Country information element is included in Beacons and Probe Responses • The regulatory maximum transmit power for a channel is specified by the Maximum Transmit Power Level field • Maximum Transmit Power Level field is specified in dBm (EIRP) Country String(octets 1, 2) Country String(octet 3) First Channel Number Number of Channels Maximum Transmit Power Level … … First Channel Number Number of Channels Maximum Transmit Power Level Pad (if needed) Infrastructure – Country information element Aachen Uni, Broadcom, Cisco, Nokia & Philips

6. Power Constraint information element is used to communicate the local maximum transmit power constraint One octet One octet One octet Element ID Length Local Maximum Transmit Power 36 1 Encoding Relative power (dB) XXXX1111 0 XXXX1100 -3 • Power Constraint information element is included in Beacons and Probe Responses • The local maximum transmit power for the current channel is specified relative to the regulatory maximum transmit power defined by the Country information element in 802.11d XXXX1100 -6 … … XXXX0001 -42 XXXX0000 reserved Infrastructure – Power Constraint information element Aachen Uni, Broadcom, Cisco, Nokia & Philips

7. Power Capability information element is used to communicate an STA’s transmit power capability to an AP One octet One octet One octet Element ID Length Maximum Transmit Power Capability 37 1 Signed number representing capability from –127 to 128 dBm • Power Capability information element is included in Association Requests and Reassociation Requests (and so only relevant in a BSS) Infrastructure – Power Constraint information element Aachen Uni, Broadcom, Cisco, Nokia & Philips

8. Capability information fixed field contains a new bit indicating TPC capability Two octets Capability Information fixed field Bit Sub-field • Capability information fixed field is included in Beacons, Association Request/Response, Reassociation Request/Response and Probe Response • Any stations that is willing to use its TPC capability shall set the TPC bit … … 11 TPC … … Infrastructure – Power Capability information element Aachen Uni, Broadcom, Cisco, Nokia & Philips

9. A hidden station frame and element contains information relating to a potential hidden station notification or reply One octet One octet One octet The status of the indication or reply Element ID Length Status Rate Rate at which the hidden station was detected Detector STA that detected the potential hidden station Via The STA to whom the report will be sent via Hidden The STA that might be hidden from the Detector Infrastructure – Hidden station Aachen Uni, Broadcom, Cisco, Nokia & Philips

10. TPC Overview of Joint Proposal Procedures Aachen Uni, Broadcom, Cisco, Nokia & Philips

11. TPC defines procedures that enable the selection of transmit powers within regulatory and local constraints • Defined TPC procedures include: • STA’s starting an IBSS and AP’s define and communicate regulatory and local transmit power constraints • STA’s joining a BSS communicate their transmit power capability to the AP • Stations select transmit powers for each MPDU within defined local and regulatory constraints Procedures - Selection Aachen Uni, Broadcom, Cisco, Nokia & Philips

12. In a BSS: The AP defines regulatory and local transmit power constraints using Country and Power Constraint information elements The AP communicates the transmit power constraints in Beacons and Probe Responses The AP may change the local transmit power constraint over the life of the BSS In an IBSS: The STA starting the IBSS defines regulatory and local transmit power constraints using Country and Power Constraint information elements All STA’s communicate the transmit power constraints in Beacons and Probe Responses STA’s shall not change the local transmit power constraint over the life of the IBSS STA’s starting an IBSS and AP’s define and communicate regulatory and local transmit power constraints Procedures – Selection – Defining constraints Aachen Uni, Broadcom, Cisco, Nokia & Philips

13. STA’s joining a BSS communicate their transmit power capability to the AP • In a BSS: • An STA shall provide an AP with information about its transmit power capabilities, using the Power Capability information element • The AP may use this information to help determine the local power constraints for any BSS’s it starts or maintains • The AP may reject a (Re)Association Request based on an STA’s transmit power capabilities Procedures – Selection – Communicating capabilities Aachen Uni, Broadcom, Cisco, Nokia & Philips

14. Stations select transmit powers for each MPDU within defined local and regulatory constraints • AP in a BSS • STA in BSS or IBSS Other STA’s • AP may transmit at any power that satisfies the regulatory transmit power constraint • AP shall ensure it respects the regulatory mitigation requirement for the channel • STA may transmit at any power that satisfies local transmit power constraint • A recommended transmit power for an STA in DCF mode is equal to highest power within the STA’s capability that less or equal to the local transmit power constraint • An STA not yet operating in a BSS or IBSS may transmit at any power that satisfies any known regulatory transmit power constraint • The STA shall ensure it respects the regulatory mitigation requirement for the channel Procedures – Selection – Selecting transmit power Aachen Uni, Broadcom, Cisco, Nokia & Philips

15. TPC defines support procedures that may assist the operation of any autonomous transmit power selection algorithms • Defined TPC support procedures: • Transmit power reporting using the SERVICE field provides a way for stations to estimate path loss for use in transmit power selection • Hidden station detection and reporting provides an input into heuristic transmit power selection algorithms Procedures - Support Aachen Uni, Broadcom, Cisco, Nokia & Philips

16. Transmit power reporting using the SERVICE field provides a way for stations to estimate path loss for use in transmit power selection Two octets PLCP SERVICE field Transmitted Power Scrambler initialisation Reserved Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Value 0 0 0 0 0 0 0 T1 T2 T3 T4 0 0 0 0 0 Encoding Relative power (dB) • Augmented SERVICE field shall be utilised by all 802.11h compliant stations • Transmitted Power field encodes the transmit power for the PPDU relative to the regulatory power constraint 1111 0 1100 -3 … … 0001 -42 0000 reserved Procedures – Support – Transmit power reporting Aachen Uni, Broadcom, Cisco, Nokia & Philips

17. Hidden station detection and reporting provides an input into heuristic transmit power selection algorithms 5 AP passes on reply from STA2 to STA1 Note: AP can use information from messages for other purposeseg setting local transmit power constraint AP Note: Stations need to deal with false positive and false negative detections 3 AP decides to pass on notify (could reject and reply immediately) 4 STA replies to STA1 via AP, possibly after adjusting power 2 STA1 decides to notify STA2 via AP (using back-off) STA1 STA2 1 Detect potential hidden station – STA2 (implementation dependent) Procedures – Support – Hidden station detection and reporting Aachen Uni, Broadcom, Cisco, Nokia & Philips