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WLPC AggregationTenTalk Purvis v4
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Friend or Foe? 802.11 Aggregation Wes Purvis @realwespurvis Technical Marketing Engineer, Cisco February 24, 2016 #WLPC
Transcript of WLPC AggregationTenTalk Purvis v4
Friend or Foe?802.11 AggregationWes Purvis - @realwespurvisTechnical Marketing Engineer, CiscoFebruary 24, 2016 - #WLPC
2© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Public
How does 802.11n/ac achieve high throughput?
Increased Modulation
Wider Channel Bandwidth
Multiple Input Multiple Output (MIMO) Frame Aggregation
3264
=12
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Why Aggregation?
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Aggregation Types
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
PHY header
MAC header MSDU1 SI
FS PHY header ACK PHY
headerMAC
header MSDU2 SIFS PHY
header ACK
back
off
PHY header
MAC header MSDU4 SI
FS PHY header ACK
back
off
PHY header
MAC header MSDU3 SI
FS PHY header ACK
back
off
NO AGGREGATION
PHY header
MAC header MSDU1 MAC
header MSDU2 MAC header MSDU3 MAC
header MSDU4 SIFS PHY
headerBlock ACK
PHY header
MAC header MSDU1 MSDU2 MSDU3 MSDU4 SI
FS PHY header ACK
A-MPDU AGGREGATION
A-MSDU AGGREGATION
PHY header
MAC header MSDU1 MSDU2 MAC
header MSDU3 MSDU4 SIFS PHY
headerBlock ACK
A-MPDU OF A-MSDU AGGREGATIONA-MSDU subframe header
MPDU Delimiter
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802.11n/ac aggregation• A-MPDU is aggregation of MPDUs
• Each MPDU has its own MAC header, CRC. Selective ACKing!
• More frames transmitted per channel access. Less overhead.
• A-MPDU is key for throughput and channel efficiency.
• Double aggregation –A-MPDU of A-MSDUs
• 11n 64k, 11ac can go up to 1MB!
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Blue bars – Typical throughput
Theoretical Max Throughput – assuming good, not perfect, RF conditions
Many APs/ 11ac clients support 64 frames in
an AMPDU
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Most vendors/ 11ac clients support two AMSDUs in AMPDU
Theoretical Max Throughput – assuming good, not perfect, RF conditions
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AMPDU Structure
RSSI last frame only
Block Ack
Beamforming2 AMPDU of AMSDU
AMPDU Length
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8 MSDU Long AMPDU
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When is aggregation not so good?
(And other time sensitive applications)
Voice
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