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802.11ac Overview

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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...

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...

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802.11ac Overview

  1. 1. RUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL Ruckus on 802.11ac April 2013
  2. 2. 802.11ac - An Overview RUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL2 5 GHz Only Optimistic Specs Multi-user MIMO (MU-MIMO) o Breaks “gigabit” barrier o Max of 6.9 Gbps o “Gimmick” specs that drive data rates very high o Many features not practical for real-world enterprises o Encourages 5G adoption o Focuses on capacity-rich, low-interference spectrum o Benefits entire Wi-Fi ecosystem Up to 8 spatial streams A P o N-fold efficiency improvement o Increases radio complexity, power draw, and cost o Requires client-side support o Not possible today o Simultaneous downlink Tx to single-stream clients o Multiples network capacity o Key differentiator from 802.11n 5G 2.4G 256-QAM o More efficient modulation o 33% data rate gains o Very short ranges only o Requires 11ac clients 80/160 MHz channels o Very wide channels o Primary reason for 11ac’s very high data rates o Ineffective use of spectrum in multi-AP environments o Decreases total capacity 160 4 0 2 0 8 0
  3. 3. o 11ac supports 5 GHz frequencies only o Dual-band devices will support 11n in 2.4 GHz o Focuses on spectrum with more bandwidth, less interference, and better scalability and capacity o Encourages client device suppliers to adopt 5 GHz, to benefit from 11ac marketing, leaving 2.4 GHz as “best effort” spectrum 3 5 GHz Only RUCKUS PROPRIETARY AND CONFIDENTIAL 480 MHz 25 channels 83.5 MHz 3 channels Capacity
  4. 4. 4 80 and 160 MHz Channels RUCKUS PROPRIETARY AND CONFIDENTIAL o 11ac devices must support 80 MHz channel width o Optional support for 160 MHz o Contiguous or non-contiguous (80+80) o Boosts maximum 802.11ac specs o Appeal is for consumers with 1 AP 20 MHz 40 MHz 80 MHz 160 MHz 160 MHz (80+80) 114 38 46 54 62 102 110 118 126 134 151 159 42 58 106 122 155 50 36 40 44 48 52 56 60 64 100 104 108 120 112 116 124 128 132 136 140 153 157 161 165 149 5170 MHz 5330 MHz 5490 MHz 5730 MHz 5835 MHz 5735 MHz UNII-1 UNII-2 UNII-2e UNII-3/ISM 802.11a/b/g 802.11n 802.11ac Red channels are not permitted in some regions 25 12 6 2 2 Total 9 4 2 0 1 144 142 138 DFS OVERVIEW Cons Pros o Max data rate is more than doubled o Boosts throughput in networks with few APs o Improves backup, file transfer speeds o Sub-optimal spectral reuse in multi-AP deployments o Max of 5 non-overlapping 80 MHz channels o Increases neighbor interference and contention o Likely decreases aggregate capacity in enterprise
  5. 5. Artificially bloats max data rates of 802.11ac 5 Spatial Streams RUCKUS PROPRIETARY AND CONFIDENTIAL 8x8:8 (MIMO) 8x8:8 (MIMO) Bandwidth 1ss 2ss 3ss 4ss … 8ss 20 MHz 78 156 260* 312 … 624 40 MHz 180 360 540 720 … 1440 80 MHz 390 780 1170 1560 … 3120 256-QAM, 800 ns GI o Business o Increases AP/client cost o Increases AP/client size o Decreases aesthetic appeal o 2x2 APs often meet the business need o Technical o Short range for 4+ streams o More streams require RF “differentiation” (difficult with 4+ streams) o Adds power draw on APs (PoE power budget) and clients (battery life) Real-World Barriers 802.11ac defines up to 8 spatial streams 802.11n defined up to 4 spatial streams Flagship devices today support up to 3SS Enterprises often prefer cost/performance of 2x2 APs
  6. 6. 6 256-QAM RUCKUS PROPRIETARY AND CONFIDENTIAL 256- QAM64-QAM16-QAM QPSKBPSK 0 1 01 11 00 10 100% gain (2x) 100% gain (2x) 50% gain (1.5x) 33% gain (1.3x) o 256-QAM improves efficiency by 33% o Higher-order modulation adds complexity, which requires higher SNR o Beneficial near the AP o Efficiency gain from modulation does not increase linearly o Requires 802.11ac AP and client
  7. 7. 7 Multi-User MIMO (MU-MIMO) RUCKUS PROPRIETARY AND CONFIDENTIAL o Transmit simultaneous downlink frames to different receivers o Significant capacity enhancements in environments with many single- stream devices (tablets, smartphones) o Requires 11ac client(s) with TxBF feedback/support o Creates new challenges related to signal steering and isolation o How to get… 4x4:4 Access Point 4x4:4 Access Point Multi-User MIMO Multiple downlink Tx at same time Single-User MIMO Single downlink Tx at a time o DataA to StaA o DataB to StaB o No DataA to StaB o No DataB to StaA
  8. 8. Payload MAC Header PHY Header Interframe Space Random Backoff Interframe Space ACK Overhead Effective Overhead Time *Note: Diagrams are not to scale and are conceptual only Payload MAC Header PHY Header Interframe Space Random Backoff Interframe Space ACK Overhead Effective Overhead Payload MAC Header PHY Header Interframe Space Random Backoff Interframe Space ACK Overhead Effective Overhead Why throughput does not equal data rate… 8 Large(r) Frame Size RUCKUS PROPRIETARY AND CONFIDENTIAL The Solution: increase payload size o Every data frame in 802.11ac is an A-MPDU o Better spectrum efficiency enables larger frame sizes without adverse impact from interference o Use of large frames depends on high rates PHY Aggregation Max Bytes (Layer 2) Max Bytes (Layer 1) 11b N (fragmentation often used) 2,304 ~2,336 11a/g N 2,304 ~2,336 11n Y 7,935 65,535 11ac 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, using protection 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 in 5G. 11ac may eventually be introduced to 2.4G for benefits from added spatial streams or 256-QAM. Will it require new hardware? Yes. For every supplier, all APs and clients will need new hardware, whether complete AP replacement or modular radio add-ons. Controllers or management software may be software upgradeable. 9 FAQ RUCKUS PROPRIETARY AND CONFIDENTIAL A: Q: A: Q: A:
  10. 10. 11ac in Waves 10 Net gain Slight efficiency improvement, most benefits are for 802.11ac devices Wave 1 – Q3, 2013 256-QAM 33% gain at very short range 80 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 capacity and efficiency, ALL devices benefit Wave 2 – Late 2014 Wave 1+ Includes all Wave 1 features, with additional chip improvements 80 / 160 MHz channels Twice the capacity of 80 MHz 802.11ac (but not recommended for multi-AP deployments) 3+ spatial streams Likely 4 spatial streams. N-fold throughput gain for high-end clients, more flexibility/capacity for MU-MIMO MU-MIMO Up to 4x capacity boost, multiplies aggregate capacity
  11. 11. Better 11ac with Ruckus Making the most of next-generation Wi-Fi 11 RUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL
  12. 12. 12 Maximizing 256-QAM RUCKUS PROPRIETARY AND CONFIDENTIAL BPSK DPSK 16-QAM 64-QAM 256-QAM o With per-packet adaptive antenna control, polarization diversity, and active channel selection techniques, Ruckus APs maximize the potential of 256-QAM with 11ac o Greater SNR/SINR increases the useful downlink range of 256-QAM o Adaptive PD-MRC and higher uplink receive sensitivity increase uplink range of 256-QAM o APs select channels with more capacity and less noise and interference Them Us
  13. 13. 13 BeamFlex-Enhanced MU-MIMO RUCKUS PROPRIETARY AND CONFIDENTIAL Antenna 2 to Client 2Antenna 1 to Client 1 Antenna 3 to Client 3 3x3 MU-MIMO 3 clients concurrently communicate with AP, each on a dedicated spatial stream (and antenna) MU-MIMO enhanced with BeamFlex Directional antenna element for each client o Better signal separation o Higher sustained data rates o Increased AP capacity Standard MU-MIMO All clients hear all antennas o Poor signal isolation per client o Lower SNR per link = lower data rates o Marginal benefit to capacity

Editor's Notes

  • New Channel Terminology:20 MHz - 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116,120, 124, 128, 132, 136, 140, 144, 149, 153, 161, 165, 169 40 MHz - 38, 46, 54, 62, 102, 110, 118, 126, 134,142, 151, 159 80 MHz - 42, 58, 106, 122, 138, 155160 MHz - 50, 114
  • Each antenna achieves directivity adapted individual clients, so each client hears its dedicated antenna best

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