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802.11ac Overview


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Overview of the upcoming 802.11ac standard and what to expect from wave 1 and wave 2 products.
Customer expectations vs. the real features which are going to be available in "wave 1" and "wave 2" products. To avoid the unnecessary frustration...

Published in: Technology, Business
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802.11ac Overview

  2. 2. 802.11ac - An OverviewRUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL25 GHz OnlyOptimisticSpecsMulti-user MIMO(MU-MIMO)o Breaks “gigabit” barriero Max of 6.9 Gbpso “Gimmick” specs that drivedata rates very higho Many features not practicalfor real-world enterpriseso Encourages 5G adoptiono Focuses on capacity-rich,low-interference spectrumo Benefits entire Wi-FiecosystemUp to 8 spatialstreamsAPo N-fold efficiencyimprovemento Increases radio complexity,power draw, and costo Requires client-side supporto Not possible todayo Simultaneous downlink Tx tosingle-stream clientso Multiples network capacityo Key differentiator from802.11n5G2.4G256-QAMo More efficient modulationo 33% data rate gainso Very short ranges onlyo Requires 11ac clients80/160 MHzchannelso Very wide channelso Primary reason for 11ac’svery high data rateso Ineffective use of spectrumin multi-AP environmentso Decreases total capacity160402080
  3. 3. o 11ac supports 5 GHzfrequencies onlyo Dual-band devices willsupport 11n in 2.4 GHzo Focuses on spectrum withmore bandwidth, lessinterference, and betterscalability and capacityo Encourages client devicesuppliers to adopt 5 GHz, tobenefit from 11acmarketing, leaving 2.4 GHzas “best effort” spectrum35 GHz OnlyRUCKUS PROPRIETARY AND CONFIDENTIAL480 MHz25 channels83.5 MHz3 channelsCapacity
  4. 4. 480 and 160 MHz ChannelsRUCKUS PROPRIETARY AND CONFIDENTIALo 11ac devices must support 80 MHzchannel widtho Optional support for 160 MHzo Contiguous or non-contiguous (80+80)o Boosts maximum 802.11ac specso Appeal is for consumers with 1 AP20 MHz40 MHz80 MHz160 MHz160 MHz(80+80)11438 46 54 62 102 110 118 126 134 151 15942 58 106 122 1555036404448525660641001041081201121161241281321361401531571611651495170MHz5330MHz5490MHz5730MHz5835MHz5735MHzUNII-1 UNII-2 UNII-2e UNII-3/ISM802.11a/b/g802.11n802.11acRed channels are not permittedin some regions2512622Total94201144142138DFSOVERVIEWConsProso Max data rate is more than doubledo Boosts throughput in networks with few APso Improves backup, file transfer speedso Sub-optimal spectral reuse in multi-AP deploymentso Max of 5 non-overlapping 80 MHz channelso Increases neighbor interference and contentiono Likely decreases aggregate capacity in enterprise
  5. 5. Artificially bloats max data rates of 802.11ac5Spatial StreamsRUCKUS PROPRIETARY AND CONFIDENTIAL8x8:8 (MIMO) 8x8:8 (MIMO)Bandwidth 1ss 2ss 3ss 4ss … 8ss20 MHz 78 156 260* 312 … 62440 MHz 180 360 540 720 … 144080 MHz 390 780 1170 1560 … 3120256-QAM, 800 ns GIo Businesso Increases AP/client costo Increases AP/client sizeo Decreases aesthetic appealo 2x2 APs often meet the business needo Technicalo Short range for 4+ streamso More streams require RF “differentiation”(difficult with 4+ streams)o Adds power draw on APs (PoE powerbudget) and clients (battery life)Real-World Barriers802.11ac defines up to 8 spatial streams802.11n defined up to 4 spatial streamsFlagship devices today support up to 3SSEnterprises often prefer cost/performanceof 2x2 APs
  6. 6. 6256-QAMRUCKUS PROPRIETARY AND CONFIDENTIAL256-QAM64-QAM16-QAMQPSKBPSK0 101 1100 10100% gain (2x)100% gain (2x) 50% gain (1.5x) 33% gain (1.3x)o 256-QAM improves efficiency by 33%o Higher-order modulation addscomplexity, which requires higher SNRo Beneficial near the APo Efficiency gain from modulation doesnot increase linearlyo Requires 802.11ac AP and client
  7. 7. 7Multi-User MIMO (MU-MIMO)RUCKUS PROPRIETARY AND CONFIDENTIALo Transmit simultaneous downlink frames to different receiverso Significant capacity enhancements in environments with many single-stream devices (tablets, smartphones)o Requires 11ac client(s) with TxBF feedback/supporto Creates new challenges related to signal steering and isolationo How to get…4x4:4Access Point4x4:4Access PointMulti-User MIMOMultiple downlink Tx at same timeSingle-User MIMOSingle downlink Tx at a timeo DataA to StaA o DataB to StaB o No DataA to StaB o No DataB to StaA
  8. 8. PayloadMACHeaderPHYHeaderInterframeSpaceRandomBackoffInterframeSpaceACKOverhead Effective OverheadTime*Note: Diagrams are not to scale and are conceptual onlyPayloadMACHeaderPHYHeaderInterframeSpaceRandomBackoffInterframeSpaceACKOverhead Effective OverheadPayloadMACHeaderPHYHeaderInterframeSpaceRandomBackoffInterframeSpaceACKOverhead Effective OverheadWhy throughput does not equal data rate…8Large(r) Frame SizeRUCKUS PROPRIETARY AND CONFIDENTIALThe Solution: increase payload sizeo Every data frame in 802.11ac is an A-MPDUo Better spectrum efficiency enables larger frame sizeswithout adverse impact from interferenceo Use of large frames depends on high ratesPHY AggregationMaxBytes(Layer 2)Max Bytes(Layer 1)11bN (fragmentationoften used)2,304 ~2,33611a/g N 2,304 ~2,33611n Y 7,935 65,53511ac Y 11,454 1,048,575
  9. 9. Q: Is it be backward compatible with 11a/n?Yes. 11ac is fully backward compatible with 802.11a/n, usingprotection mechanisms with 11a/n frame formats.What about 2.4 GHz?Initially, dual-band APs will be 802.11n in 2.4G and 802.11ac in5G. 11ac may eventually be introduced to 2.4G for benefits fromadded spatial streams or 256-QAM.Will it require new hardware?Yes. For every supplier, all APs and clients will need newhardware, whether complete AP replacement or modular radioadd-ons. Controllers or management software may be softwareupgradeable.9FAQRUCKUS PROPRIETARY AND CONFIDENTIALA:Q:A:Q:A:
  10. 10. 11ac in Waves10Net gain Slight efficiency improvement, mostbenefits are for 802.11ac devicesWave 1 – Q3, 2013256-QAM 33% gain at very short range80 MHz channels Twice the capacity of 40 MHz 802.11n(but not recommended for multi-AP deployments)3 spatial streams Already supported by 802.11n (3x3)Net gain Multiples aggregate network capacityand efficiency, ALL devices benefitWave 2 – Late 2014Wave 1+ Includes all Wave 1 features, with additional chip improvements80 / 160 MHz channelsTwice the capacity of 80 MHz 802.11ac(but not recommended for multi-AP deployments)3+ spatial streamsLikely 4 spatial streams. N-fold throughput gain for high-end clients,more flexibility/capacity for MU-MIMOMU-MIMO Up to 4x capacity boost, multiplies aggregate capacity
  11. 11. Better 11ac with RuckusMaking the most of next-generation Wi-Fi11 RUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL
  12. 12. 12Maximizing 256-QAMRUCKUS PROPRIETARY AND CONFIDENTIALBPSKDPSK16-QAM64-QAM256-QAMo With per-packet adaptive antenna control, polarization diversity, and active channelselection techniques, Ruckus APs maximize the potential of 256-QAM with 11aco Greater SNR/SINR increases the useful downlink range of 256-QAMo Adaptive PD-MRC and higher uplink receive sensitivity increase uplink range of 256-QAMo APs select channels with more capacity and less noise and interferenceThem Us
  13. 13. 13BeamFlex-Enhanced MU-MIMORUCKUS PROPRIETARY AND CONFIDENTIALAntenna 2 to Client 2Antenna 1 to Client 1Antenna 3 to Client 33x3 MU-MIMO3 clients concurrently communicatewith AP, each on a dedicated spatialstream (and antenna)MU-MIMO enhanced with BeamFlexDirectional antenna element for each cliento Better signal separationo Higher sustained data rateso Increased AP capacityStandard MU-MIMOAll clients hear all antennaso Poor signal isolation per cliento Lower SNR per link = lower data rateso Marginal benefit to capacity