April 2014 doc.: IEEE 802.11-14/0523r0 MAC simulation results for Dynamic sensitivity control (DSC - CCA adaptation) and transmit power control (TPC) Date: 2014-04-17 Authors: Name Company Address Imad Jamil Orange Laurent Cariou Orange Thomas Derham Orange Jean-Pierre Le Rouzic Orange 4 rue du clos Courtel 35512 Cesson Sévigné France 4 rue du clos Courtel 35512 Cesson Sévigné France 9F Keio Shinjuku Oiwake Bldg. Shinjuku 3-1-13, Tokyo, Japan 4 rue du Clos Courtel 35512 Cesson Sevigne France Submission Phone Slide 1 email [email protected] +33 299124350 [email protected] +81 3 5312 8563 [email protected] +33 299124893 [email protected] Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Context • In dense environments, CSMA-CA parameters (especially CCA physical carrier sensing) as defined in the standard are quite conservative. – reducing reuse between neighboring cells • Several presentations have takled this problem: – adaptation of this CCA (dynamic sensitivity control) – adaptation of transmit power • In this presentation, we run a set of simulations to confirm/infirm first insights regarding these schemes – MAC system simulator with simple PHY abstraction Submission Slide 2 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 co-channel interference (CCI) from neighboring cells Useful Rx power AP Min SINR to receive MCSx (sensitivity) STA CCI Co-Channel interference (CCI) CCA CCI Noise floor Interfering AP Simultaneous transmission STA • In scenarios where the useful receive power is always sufficiently higher than interference, reuse between neighboring cells is possible – but currently prevented by CCA threshold Submission Slide 3 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 How to enable reuse 1: Transmit power control 2: CCA control (DSC) AP AP STA STA Co-Channel interference (CCI) Co-Channel interference (CCI) Interfering AP STA Interfering AP Simultaneous STA transmission Simultaneous transmission Useful Rx Power CCI CCA Submission Useful Rx Power Min SINR to receive MCSx (sensitivity) Min SINR to receive MCSx (sensitivity) CCI CCI CCA Noise floor Slide 4 Noise floor Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Simulate simple algorithms • DSC (CCA control): – each STA adjust CCA to CCA = Useful Rx Power – Margin AP STA tune CCA level tune CCA level (and receiver sensitivity) • TP control: • each receiver requests transmitter to adjust TP so that it receives the Useful Rx Power at Margin dB above classical CCA (-82dBm) AP tune TP STA • In each case, the margin has a strong relationship with the min SINR experienced by STAs – we are not discussing any protocol in here Submission Slide 5 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Simulation scenario BSS Cluster 3 Submission Slide 6 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Simulation scenario Close to scenario 3 - First tier only (7 BSSs), 8 STAs per BSS, Single channel for reuse 3 Tx : 15 dBm [21 m] [7 m] Tx :15 dBm Submission Slide 7 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Simulation scenario Parameters PHY oIEEE 802.11n oPath Loss: ITU UMi (23.3+36.7log10(d)+ 21log10(2400/900MHz)) oBand: 5 Ghz oChannel: 20 MHz oTx power: 15 dBm Traffic oFull buffer UDP traffic oDL (AP->STA) oUL (STA->AP) Simple metric Aggregate throughput Fixed MCS or rate adaptation AARF Submission Slide 8 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Fixed MCS7 – DSC and TPC Different margin (10-15-20-25-30-35-40-50) No DSC Submission No TPC DSC Slide 9 TPC Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Rate control – DSC and TPC Different set of MCSs for rate control: all MCSs, MCS 2-7, MCS 3-7, MCS 4-7, MCS 5-7, MCS 6-7 No DSC Submission No TPC DSC Slide 10 TPC Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 First observations • CCA and TPC are strongly increasing reuse and aggregate throughput – Margin optimization • Weak rate control algorithms make aggregate throughput collapse • The margin gives an indication on min SINR – if used for suppression of MCS usage below this min SINR – it leads to strong improvement of rate control efficiency and to aggregate throughput gains Submission Slide 11 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Impact of legacy devices • mix of legacy (not implementing DSC or TPC) and DSC/TPCcapable STAs (implementing DSC or TPC) – 1 legacy STA per BSS Submission Slide 12 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Rate control – DSC– mix with legacy devices All DSC-capable STAs No DSC Submission DSC-capable STAs + 7 legacy STAs DSC No DSC Slide 13 DSC Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Rate control - TPC – mix with legacy devices All TPC-capable STAs No TPC Submission TPC-capable STAs + 7 legacy STAs TPC No TPC Slide 14 TPC Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 First observations for mix with legacy • As expected, the impact of legacy devices on aggregate throughput is way stronger with TPC than with DSC – with TPC, those legacy are disabling any reuse possibility – with TPC, those legacy are also disturbing the relationship between the margin and the min SINR and cancels MCS suppression benefits in rate control algorithms Submission Slide 15 Imad Jamil (Orange) April 2014 doc.: IEEE 802.11-14/0523r0 Conclusion/next steps • Preliminary results with MAC system simulator are showing – very good per user throughput gains both for TPC and DSC – additional benefit of the « margin » for rate adaptation improvement through desabling the use of low MCSs – strong impact of legacy devices on TPC reuse efficiency • Next steps – – – – Submission simulator evolution (calibrated) different scenarios analysis of potential starvation of legacy devices in case of DSC analysis of RTS/CTS impact Slide 16 Imad Jamil (Orange)
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