HE LTF Proposal - IEEE Standards Association

Extended Range Support for 11ax
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Date:2015-11-09
Authors:
Sameer Vermani (Qualcomm)
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Sameer Vermani (Qualcomm)
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Sameer Vermani (Qualcomm)
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Sameer Vermani (Qualcomm)
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Sameer Vermani (Qualcomm)
Outline
In [1], it was proposed to have a repeated HE-SIG-A for range extension purposesIn these slides, we showPerformanceof the preamble with repeated HE-SIG-ALook at performance bottlenecks of the preamble performanceCan remove/mitigate the bottlenecks of preamble performance through L-STF/LTF boost5-6dBperformance gain is on offer through the extended range modeMeasured as preamble performance advantage over MCS0 20MHz payloadBased on above, propose power-boosting the L-STF and L-LTF by 3dB for the extended range mode
Sameer Vermani (Qualcomm)
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Normal Mode
Range extension mode
Supporting the Extended Range Mode
Preamble needs to keep up with lower SNR operation to realize the range benefitDoing it within the existing preamble framework is possibleBy repeating L-SIG,HE-SIGA [1]Possible3dB power boosting of some training fields if neededIn the following slides, we study the performance of the preamblewith HE-SIG-A repetitionLook at the performance bottlenecks in the preambleL-STF becomes a bottleneckCan be removed by boosting it by 3dBOnce L-STF bottleneck is removed, repeated HE-SIG-A decoding or RL-SIG detection becomes the bottle neckMitigated by boosting L-LTF by 3dBAlso, answerthequestion: Eventually,howmuchbetter can the preamble perform compared to MCS0 data?
Sameer Vermani (Qualcomm)
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Simulations
Analyzed the capability of the HE preamble in the presence of SIG field repetition for the following 3 cases:Without any training field boostWith L-STF power boostWith L-STF and L-LTF power boostParameters usedD-NLOS channel32 byte and 1000 byte packetsBCC codingLooked at both 1 % and 10% PERsAll impairments and tracking loops are turned ON4 symbol SIG-Aused (with repetition)Realistic PA model to model the impact of clipping when STF/LTF are boosted
Sameer Vermani (Qualcomm)
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Performance of existing preamble with SIG repetition in absence of any training field boost
Green columns show MCS0 payload-only performanceWe show performance of various sub-fields of the preamble and show what is the bottle neck in redL-STF is the bottle-neck in this caseThe gain on offer by going to lower data-rates is shown belowDifference in the preamble bottle-neck and payload performance
Sameer Vermani (Qualcomm)
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Performance of existing preamble with SIG repetitionwith L-STF boost
Green columns show MCS0 payload-only performanceWith L-STF boosted, it no longer remains the bottle neckRL-SIG detection and HE-SIG-A decoding is the bottle-neck in this case at 1% and 10% respectivelyThe gain on offer by going to lower data-rates is shown belowDifference in the preamble bottle-neck and payload performance
Sameer Vermani (Qualcomm)
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Performance of existing preamble with SIG repetitionwith L-STF & L-LTF boost
Green columns show MCS0 payload-only performanceWith both L-STF and L-LTF boostedL-STF detection and HE-SIG-A decodingarethebottle-necksat 1% and 10%PER respectivelyThe gain on offer by going to lower data-rates is shown belowDifference in the preamble bottle-neck and payload performance
Sameer Vermani (Qualcomm)
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Summary
When compared to MCS0 payload performance5-6 dB better preamble performance is on offer by introducing lower data rates in payload and repetition of SIG fields in the existing SU preambleBoosting of L-STF increases the gain by another 1dB at 1% PERBoosting of both L-STF & L-LTF increases the gain even furtherPower boost on L-STF and L-LTFis needed to maximize the gain of the extended range modePropose a 3dB boost on both the fields
Sameer Vermani (Qualcomm)
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Pre-motion 1
Do you support adding the following tothe specframework“L-STFpower is boosted by 3 dB inthe extendedrangepreamble”
Sameer Vermani (Qualcomm)
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Pre-motion 2
Do you support adding the following tothe specframework“L-LTFpower is boosted by 3 dB inthe extendedrangepreamble”
Sameer Vermani (Qualcomm)
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References
[1] 11-15-0826-03-00ax-he-sig-a-transmission-for-range-extension
Sameer Vermani (Qualcomm)
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