Gigabit WiFi: Utilising 802.11ac on Campus Considerations and Benefits Paul Lambert Consulting Systems Engineer, UK & Ireland
802.11ac Standard Highlights What s in the 802.11ac Standard Very High Throughput (VHT) - up to 10x compared with11n Wider channels: 80MHz, 160MHz, 80+80MHz (4X) New modulation: 256-QAM (1.3X) More MIMO streams: up to 8 (2X) Well defined Beam Forming Multi-User-MIMO (MU-MIMO) 3
802.11ac Data Rate Matrix Data Rates in 802.11ac Rates in Mbps 20MHz 40MHz 80MHz 160MHz 1 stream 86.7 200 433.3 866.7 2 streams 173.3 400 866.7 1733.3 3 streams 288.9 600 1300 2340 4 streams 346.7 800 1733.3 3466.7 5 streams 433.3 1000 2166.7 4333.3 6 streams 577.8 1200 2340 5200 7 streams 606.7 1400 3033.3 4095 8 streams 693.3 1600 3466.7 6933.3 Expected in the first generation of silicon 4
36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 165 Wider channels: 80Mhz and 160Mhz 5170 MHz 5330 MHz 5490 MHz DFS Weather radar Not allowed in North America 5730 MHz 5735 MHz Not allowed in Europe 5835 MHz IEEE channel # 20 MHz 40 MHz 80 MHz 160 MHz Dynamic Frequency Selection Available Channels for 802.11ac Using DFS Channels Without DFS Channels Channel Size US Europe US Europe 40 MHz 8 9 4 2 80 MHz 4 5 2 1 160 MHz 1 2 5
Data Rate Table Standard Bandwidth Spatial Streams PHY Data Rate Real Throughput 802.11a 20 MHz 1 54 Mbps 24 Mbps 802.11n 20 MHz 1 65Mbps 46 Mbps 802.11n 40 MHz 2 300 Mbps 210 Mbps 802.11n 40 MHz 3 450 Mbps 320 Mbps 802.11ac Phase I 80 MHz 1 293Mbps 210 Mbps 802.11ac Phase I 80 MHz 2 867 Mbps 610 Mbps 802.11ac Phase I 80 MHz 3 1300 Mbps 910 Mbps 802.11ac Phase II 160MHz 1 867 Mbps 610 Mbps 802.11ac Phase II 160 MHz 2 1730 Mbps 1200 Mbps 802.11ac Phase II 160 MHz 3 2600 Mbps 1800 Mbps 802.11ac Phase II 160 MHz 8* 6933 Mbps 4900 Mbps * There are no commercial implementations that use more than 3 spatial streams
Rate and Range Power and space challenges are still the same Don t expect more than 3 data streams soon (-) Higher rates available at ranges closer to the AP (-) Higher throughput efficiency mean less time (power) spent for transmit (+) Users will still observe greater net throughput (+) Thank You
Predicted Uptake Questions?
Beamforming Introduced in 802.11n 802.11n had many options no vendor implemented it 802.11ac uses a single standard for beam forming 9
Beamforming By changing time (phase) of 3 transmitters, 802.11ac AP s can create a constructive interference transmit beam-forming waveform (TxBF) and generate a stronger signal that clients can hear better. Without Beamforming 1 st Stream With Beamforming 1 st Stream AP 2 nd Stream 3 rd Stream 11ac AP 2 nd Stream 3 rd Stream Destructive Interference, when three streams of RF energy cancel each other Constructive Interference, when three streams of RF energy stack up each other AP 11ac AP 10
Beamforming A standard 3x3:3SS 802.11n AP effective coverage at different modulation rates Where can I access my Wi-Fi? 802.11n 64 QAM coverage Top rate @ 450 Mbps 802.11n 16 QAM coverage Top rate @ 180 Mbps User is outside of RF coverage zone with lowest RX Z(e.g. -90 dbm receiving sensitivity) 802.11ac 256QAM 64 QAM Top rate @ 1330 Mbps GbE Zone 802.11n 64 QAM coverage Top rate @ 450 Mbps User is within RF coverage zone with due to reconstructed radio coverage (due to different phase) 802.11n 16 QAM coverage Top rate @ 180 Mbps
Multi-User MIMO Allows a sophisticated AP (#Antennas > #Streams) to maintain high throughput even when the clients are simple (smartphones, tablets, etc ) Up to four simultaneous clients, each with one or more antennas, transmit or receive independent data streams Needs MU-MIMO beam forming support Provides better channel reuse in single channel, enables high client density 4 x density Expected only in the second generation of silicon 12
802.11ac Design Considerations Survey/Plan for 5GHz coverage Old AP placements are probably based on old requirements Higher signal strength requirement for 256QAM data-rates 40 or 80MHz Support Highest data rates are only available with 80MHz channels Not all vendors are recommending 80MHz channel widths due to architectural constraints 802.3af/at PoE PD Support Some solutions require 802.3at PoE+ to operate at full performance Multiple GigE ports per AP Worth considering provision, but not a must-have Possible more benefit for resilience than performance 13
802.11ac Benefits Higher data-rates than 802.11n Gen 1 802.11ac AP s offering 1.3Gbps vs 450Mbps on 11n Greater density Higher data-rates mean clients need less time to complete their data transfers. Leaves more space for more clients Gen 2 AP s will add MU-MIMO capability Better n than n Testing from multiple vendors has shown an increase in performance in 802.11n chipsets when used on 802.11ac infrastructure - no need to wait for benefits Power consumption benefits on client devices More efficient transmissions lead to lower battery requirements 14
Bonjour! A friendly greeting, or death to your network?
Bonjour - Many Challenges Advertisement Problems Bonjour is local only, designed for home use Others use multicast Scalability Issues Bonjour doesn t scale due to Location Challenges Which services are relevant Policy and Control Who should advertise services? Who should learn about services?
Policy Policy Service Control in Action (Bonjour) Discover Consolidate Distribute Advertise POLICY CONTROLLED SERVICE DISCOVERY & ADVERTISEMENT
Service Control Use Case ESSID: student ESSID: staff Vlan 600 vlan 700 Administration Building Liberal Arts Building 18
Service Control - Discovery Global Service Discovery List Liberal Arts Liberal Arts Admin Bldg - Apple TV - Printer - Printer ESSID: student ESSID: staff Vlan 600 vlan 700 Administration Building Liberal Arts Building 19
Service Control Policy - Faculty Liberal Arts Liberal Arts Admin Bldg - Apple TV - Printer - Printer ESSID: student ESSID: staff Vlan 600 vlan 700 Administration Building Liberal Arts Building 20
Service Control Policy - Student Global Service Discovery List Liberal Arts Liberal Arts Admin Bldg - Apple TV - Printer - Printer ESSID: student ESSID: staff Vlan 600 vlan 700 Administration Building Liberal Arts Building 21
Questions???
Thank You