1. 11ac: 5G WiFi The trigger for 5GHz everywhere Led by Apple and other consumer specialists – In-home device sync, video, backup, etc – “Gigabit WiFi” on retail shelves 11ac’s best feature is that it is 5GHz only!

2. QAM bits code rateBWstreamsMAC eff. PHY Mb/s TCP Mb/s 11n 1x1, 2.4 GHz max60.8332010.657549 11n 2x2, 5 GHz max60.8334020.65300195 11n 3x3, 5 GHz max60.8334030.65450293 11n best (4x4 5GHz) max60.8334040.65600390 11ac 3x3, 80 MHz, 64QAM, max60.8338030.65975634 11ac 3x3, 160 MHz, 64QAM, max60.83316030.6519501268 11ac 4x4, 160MHz, 256QAM, max80.87516040.6536402366 11ac maximum (8x8 etc.)80.87516080.6572804732 11ac Potential Data Rates vs 11n 11ac Throughputs

3. 11ac Wave 1 80MHz channels 256QAM modulation – Potentially could be added to 2.4GHz MAC improvements Ubiquitous support on TX-BF (hopefully) Wave 2 MU-MIMO 160MHz channels – non adjacent (future?)

4. J 11ac: wider channels 80 MHz Channels 80 MHz U-NII WorldwideU-NII 3 WLAN Radar U-NII 2U-NII 1 WLAN 80 MHz Radar WLAN - 160 MHz  160 MHz (potentially noncontiguous) channels in ~2014? More spectrum coming soon

5. Dynamic bandwidth (BW) operation Currently channel must be free on whole 40MHz even if using 20MHz only – Wider channel increases likelihood of interfering signal in extension – Dynamic BW capability is desired to utilize BW more efficiently – Not required, but most vendors support it Meeting spectral mask is challenging Operating mode change requires 10s of milliseconds Secondary 40MHz Primary 20MHz Secondary 20MHz 36+404448 Mode 1 Mode 2 Mode 3

6. 11ac: 256QAM 6 ModulationSymbols Bits/ Sym. Relative speedup BPSK21 QPSK422.00 16QAM1642.00 64QAM6461.50 256QAM25681.33 QPSK 256QAM

7. 11ac MAC Changes Frame size and MAC efficiency Dynamic bandwidth operation CCA thresholds differently handled New RTS/CTS rules

8. MAC efficiency PSDU size (Bytes) 450Mbps1.3Gbps2.6Gbps UDP Goodput (Mbps) MAC efficiency UDP Goodput (Mbps) MAC efficiency UDP Goodput (Mbps) MAC efficiency 1500*3234777%73456.5%101939.2% 64K (max 11n)36280.5%81062%118045.5% 172K103880% 295K200077.5% Preamble/ PHY header MAC header Payload AIFS Random backoff t Effective Overhead Note: BestEffort QoS is assumed

9. 11ac strengthened Clear Channel Assessment (CCA) requirement Must detect WiFi signals with energy level above threshold on all channel widths – Preamble detection not required Different back-off thresholds for WiFi vs non-WiFi signals – Device must be either smart enough to differentiate WiFi signals vs other energy or use lowest threshold for all Energy Detection threshold (in dBm) for signals not occupying primary 20MHz channel 20MHz40MHz80MHz WiFi signal-72 -69 Non-WiFi signal-62-59-56

10. Under 11n RTS/CTS rules for wider channels, a responder responds with CTS using full wide channel If a transmitter receives a CTS on 20MHz channel, it responds with data using full width channel (20/40/80MHz etc.) This rule does not account for possible interference on the wider channels Primary Secondary20 time BA Secondary40 time SIFS BA RTS CTS Interference at responder RTS/CTS in 11ac

11. Wave 2 – Multi-User (MU-MIMO)

12. 11ac : DL-MU-MIMO Down-link Multi-User MIMO (spatial division multiple access) Makes use of multiple physical paths through the environment to enable multiple simultaneous transmissions to different receivers Impressive capacity improvements if you can fit 8-16 antennas per band on an AP. 12 AP PC Phone PC 2 streams 1 stream 2 streams

13. DL-MU: basic parameters Max. # of users per packet : 4 Max. # of space-time streams per user : 4 – Collision free maximum # of space-time streams for SU packet = 8 Max. total # of space-time streams over all users: 8

14. DL-MU – Spatial Multiplexing Historically – Access points and clients were using same/similar baseband MU requires different designs – AP complexity increased due to MU support in both HW and SW – MU capability costs likely to push market to different AP and client BB silicon 14 Stream 1 Stream 2 Stream 3 Stream 4 Single-User MIMO (11n)Multi-User MIMO (11ac) Stream 1 Stream 2 Stream 3 Stream 4

15. DL-MU: Sequential Block ACK Sequential Ack is used because no UL-MU support One user send immediate BA Other users are polled using BAR 15 STA 1 STA 2 STA 3 AP STA 1 STA 2 STA 3 BA BAR BA BAR BA SIFS Error Recovery (same for sounding) PIFS

16. After random back off the winning AC will be allowed to transmit Other ACs are allowed to piggy back in MU packet as long as it doesn’t extend the TXOP – If primary AC is voice, max TXOP is 1.5 seconds – If primary AC is video, max TXOP is 3 seconds DL-MU: TXOP sharing Voice (primary AC) Data Video

17. Thank You