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

2. 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

3. 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 h” (S. Choi and A. Soomro, Philips Research USA)
Peter Larsson, Ericsson Research, Sweden

4. 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: dB to -5 dB
Peter Larsson, Ericsson Research, Sweden

5. 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

6. 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

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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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