Marketing v, Reality in Multi-Antenna Wi-Fi

1. Marketing v.
Reality in Multi-
Antenna Wi-Fi
Guide to Beamforming
March 2011
Scott Reeves
Technical Director
EMEA

2. 2
Summary
 Wi-Fi vendors are marketing chip-based beamforming more heavily
 They gloss over limitations, naturally
 Mutually-exclusive chip-based beamforming and spatial multiplexing
 Zero gain from implicit beamforming, minimal (2 dB) from explicit
 Zero client support today for explicit
 Customers are easily confused, since all beamforming sounds the
same to any non-specialist
 A back-to-the-basics view (focusing on simple but technically
accurate descriptions how multi-antenna techniques really work)
can cut through the confusion
 ...and illustrate why Ruckus BeamFlex remains the superior
approach

3. 3
Conventional Wi-Fi: omni Tx pattern

4. 4
BeamFlex Smart Antennas
Auto
RF signal
optimizer
(Optimises RF coverage based on device
orientation)
Horizontally-
polarized
antenna
elements
Vertically -polarized
antenna
elements

5. 5
Automatic Interference Mitigation (AIM)
 Chip-based beamforming has no
mechanism to reject interference
 Omni-directional antennas can’t
ignore interference
 BeamFlex mitigates interference
by positioning antenna nulls in
specific directions
 Negating interference can be
more beneficial than signal gain
5
Interference Rejection is Essential
-10db
interference
rejection
7 dBi signal gain

6. 6
Key concepts: combination and phase

7. 7
How chip-based beamforming works
Understanding the narrow definition of the term “beamforming”

8. 8
Beamforming: only one signal allowed

9. 9
Chip Based Beamforming Limitations
 Generates unwanted
interference and
wastes energy
 No way to cope with
real-time interference
at the client
 Beams predicated on
antenna separation
Optimal beamforming (5GHz) calls
for .5” antenna separation
Optimal spatial multiplexing
“requires” antenna separation at
inches (5GHz)
!
Client
Client

10. 10
Not All Beams Are Created Equal
Client
Client
Client
Client
AP AP
AP AP
Antenna Pattern
Example:
Chip-based
beamforming
Antenna Pattern
Example:
Antenna-based
beamforming
 Wasted
RF energy
 Added
interference

11. 11
Spatial multiplexing is essential
Speeds in the 802.11 protocols
1
10
100
1,000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 23 31
802.11n >1stream, 40 MHz, 400ns GI
802.11n 1stream, 40 MHz, 400ns GI
802.11n >1stream, 20 MHz, 800ns GI
802.11n 1stream, 20 MHz, 800ns GI
802.11a/g
802.11b
Peak bit rate, Mbps
MCS number

12. 12
How spatial multiplexing works

13. 13
Why 3 radio chains don’t help

14. 14
Tx 1
In Phase
Tx 2
2x signal strength
Same waveform
Rx
Tx 1
Tx 2
Different coded
waveforms
(on same frequency)
Data stream
split
and cross-encoded for Tx
...0010
...1011
...1101001101
SM and chip BF are mutually exclusive
Chip-based beamforming
Spatial multiplexing
(With 1 radio chain per stream)

15. 15
BeamFlex + spatial multiplexing

16. 16
A proper multi-antenna taxonomy

17. 17
BeamFlex Antenna Advantages
 BeamFlex smart antenna:
Beamforming focuses the RF energy ensuring multipath
arrives in phase and provides maximum signal density
= extended range and superior performance
Horizontally and vertically polarised elements offer 4000+
unique antenna patterns automatically selected on a per
packet/per client basis
Attenuate interference from adjacent APs, clients and
other RF sources
Cause significantly less interference to adjacent APs
 Omni-directional antenna:
 Cannot control interference to neighbouring APs
 Multipath phasing can be a significant issue
 No interference rejection
 Make bad RF neighbors
Signal Gain
Up to 9dBi
Rejected Interference
Up to -17dB

18. 18
BeamFlex™: Interference Resistance
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60
iPhone 3G Client Throughput Comparison
Vendor CRuckus Vendor B
0.3
8.7
5.5
0.1
6.7
8.3
Test House Baseline (low interference)
High Interference Location (191 active APs in 3,000m² facility)
Throughput, Mbps
Average
Time, Seconds

19. 19
SmartMesh:
Meshing with Adaptive antenna beamforming
 Mesh-APs contiunously announce their link capacity
 Each Accesspoint selects the best path to Root-AP
 BeamFlex optimizes the signal quality to clients & mesh-APs
 Self-healing in case of an outage of a mesh-node
(also to an alternate Root AP possible)
Root
AP
ZoneDirector
controller
300 Mbps
150 Mbps 150 Mbps 75 MbpsMesh
AP

20. 20
Performance varies significantly
Note: 2.4 GHz, 800 ns GI, ETSI EIRP, 15 dB fading margin for interference
and obstructions
Sources: Ruckus testing, experience.
0
20
40
60
80
100
120
140
160
180
0 5 10 15 20 25 30 35 40 45 50
[1] .11n 1x1:1 omni
[2] .11n + Explicit Beamforming (1 stream)
[3] .11n 2x2:2 omni
[4] .11n 3x3:3 omni
[5] .11n 1x1:1 + BeamFlex
[6] .11n 2x2:2 + BeamFlex
RF Technology Comparison
Peak Throughput, Mbps
Range, m

21. 21
Net result: BeamFlex 70% better
Ruckus 3x3:2 AP
with BeamFlex
4-Year Aggregate Client Throughput per AP, Terabytes
Generic 3x3:3 AP
with Explicit
Beamforming
440
more capacity
for client service
with Ruckus
260
70%

22. 22
Case Study
Wireless Broadband Deployment
Tikona India

23. 23
The World’s Largest Wireless Mesh
Mesh
Access
Point
 Began build out in 2009
 40,000 smart mesh APs now
deployed and operational
(50k by 2011)
 Hundreds of smart WLAN
controllers
 Central management
through
FlexMaster
 Hundreds of
thousands of
users
Based on Ruckus Wireless Product and Technology End-to-End
0
2
4
6
8
10
12
14
16
18
0% 20% 40% 60% 80% 100%
802.11g outdoor AP to indoor CPE
data rates 1,670 samples on live
Tikona network
Mbps
% of CPE

24. 24
Tikona footprint
• 40,000 AP live
• 45,000AP
deployed
(approximately)

25. 25
Large-Scale Mesh Deployment
ZoneFlex 7731
Point-to-point
802.11n backhaul
FlexMaster
Remote Management
ZoneDirector
WLAN Controller
MediaFlex 2211
Bridge/Repeater
Outdoor Mesh AP
50 Mbps at
10km100 Mbps at
2km
20 Mbps at
300m/1000 ft
Backhaul
POP
NOC
WBA

26. 26
End-to-end visibility and control
 One NOC
 Multiple
cities
 Tens of
Thousands
of access
points
 Hundreds of
Thousands
of clients

27. 27
Active Antenna Beamforming Wi-Fi Portfolio
I N D O O R O U T D O O R
802.11n Bridge
802.11 n AP
802.11g
Single-band 802.11n
2X2 dual-band 802.11n
3X3 dual-band 802.11n
802.11g outdoor mesh
Dual-band 802.11n outdoor
802.11g outdoor mesh
Dual-band 802.11n outdoor
Strand-Mounted 802.11n
5GHz 802.11n PtP/PtMP
Autonomous, Controller-Based or Remotely Managed
802.11n wall switch
Sectorized dual-band 802.11n
Smart Wi-Fi
controllers for RF
and AP
management
Network and Subscriber Management
Highly-scalable centralized
network and element
management
ZoneDirector™ FlexMaster™

28. 28
Thank You
Scott Reeves
Technical Director EMEA
Ruckus Wireless
Scott@ruckuswireless.com