Proposal to Improve Link Margin Function in IEEE 802.11h November 2001 November 2001 Proposal to Improve Link Margin Function in IEEE 802.11h Peter Larsson, Ericsson Research, Sweden Peter Larsson, Ericsson Research, Sweden

Overview Review of other link margin/TPC proposals November 2001 November 2001 Overview Review of other link margin/TPC proposals A scenario with potential of improvements Proposal Format Example of transmit power determination Example of basic operation Benefits Conclusions Peter Larsson, Ericsson Research, Sweden

Review of Other Link Margin/TPC Proposals: November 2001 Review of Other Link Margin/TPC Proposals: 01/520: Benefits of TPC request/response element (Joonsuk Kim, Broadcom Corporation) 01/536: “Proposal to Add Link Margin Field in IEEE 802.11h” (S. Choi and A. Soomro, Philips Research USA) Peter Larsson, Ericsson Research, Sweden

01/536: Frame Format SERVICE field frame format Range: +9 dB to -5 dB November 2001 01/536: Frame Format SERVICE field frame format Range: +9 dB to -5 dB Peter Larsson, Ericsson Research, Sweden

01/536: Example of Operation November 2001 01/536: Example of Operation AP STA STA sends one MPDU to AP with TX Power field set AP sends ACK with TX power and Link Margin fields set Adapt TX Power: STA sends next MPDU to AP with adjusted power Adapt TX Power: AP sends ACK with TX power and Link Margin fields set Optional to adapt ! Peter Larsson, Ericsson Research, Sweden

01/536 with QoS(+)CF-POLL - DATA -ACK November 2001 01/536 with QoS(+)CF-POLL - DATA -ACK AP STA AP sends one QoS(+)CF-POLL to STA with TX Power field set STA sends DATA with TX power and Link Margin fields set More important to control transmit power for DATA than for ACK ? + Better to control STA ? Adapt TX Power: AP sends ACK to STA with adjusted power Peter Larsson, Ericsson Research, Sweden

Proposal: Service Field Format November 2001 Proposal: Service Field Format SERVICE field frame format Range: 127 dB, 1 dB steps N.B only 7 bits ! Peter Larsson, Ericsson Research, Sweden

Proposal: Transmit Power Example STA to AP transmission November 2001 Proposal: Transmit Power Example STA to AP transmission PTX_STA  INRX_AP + M +PTX + PTX_MAX- PRX_STA= INRX=Expected Interference + Receiver Noise [dBm] M= Receive Margin [dB] PTX= Transmit power [dBm]= PTX +PTX_MAX PTX=Relative transmit power reduction [dB] PTX_MAX= Maximum transmit power level for the channel [dBm] PRX= Receive power [dBm] N.B. PTX_STA < PTX_MAX Required RX power Path loss T parameter = T + PTX_MAX - PRX_STA Peter Larsson, Ericsson Research, Sweden

Proposal: Example of Operation (QoS(+)CF-POLL - DATA - ACK example) November 2001 Proposal: Example of Operation (QoS(+)CF-POLL - DATA - ACK example) AP STA Set TAP parameter AP sends QoS(+)CF-POLL with TAP parameter set. STA sends DATA to AP with adjusted power. TSTA parameter is set Adapt TX Power: OL Set TSTA parameter Adapt TX Power: OL Adjust TAP parameter AP sends ACK to STA with adjusted power. TAP parameter is adjusted OL = Open Loop CL = Closed Loop Adapt TX Power: CL Adjust TSTA parameter Peter Larsson, Ericsson Research, Sweden

Benefits A single generic mechanism enabling: OL control CL control November 2001 Benefits A single generic mechanism enabling: OL control Acts already at the 2:nd frame. CL control Acts on the 4:th frame and onwards and enables more precise control than OL. Flexibility and optional operation: Implementors decide whether OL (w/wo RX-interference) or CL is utilized. Peter Larsson, Ericsson Research, Sweden

More Benefits Minimized use of Service Field bits November 2001 More Benefits Minimized use of Service Field bits Enables additional protection of field if needed Peter Larsson, Ericsson Research, Sweden

Optional/Mandatory Features ? November 2001 Optional/Mandatory Features ? Two possibilities. STA 1 generating the T parameter (opt./mand.) STA 2 using the received T parameter (opt./mand.) Open for TGh discussion ! However, we believe that it would be good if at least the T parameter generation is Mandatory. Peter Larsson, Ericsson Research, Sweden

Conclusions An improved TPC mechanism has been proposed November 2001 Conclusions An improved TPC mechanism has been proposed Provides OL as well as CL capabilities A new service field format has been proposed Simpler and more generic than two different fields Shorter Peter Larsson, Ericsson Research, Sweden