adant ras for wifi 052016 (001)ctw2016.ieee-ctw.org/slides/ctw16_piazza.pdf · ruckus cisco aruba...
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Reconfigurable antennas for WiFinetworksDaniele Piazza
Founder and CTO – Adant Technologies Inc
Company Overview
2
Adant designs, licenses, and manufactures reconfigurable (smart) antenna systems for the
wireless communications industry
AdantSF Bay Area
AdantPadova, Italy
AdantTaiwan
Adant main markets
WIRELESS NETWORKING
HOME GATEWAY
MOBILE INTERNET
RFID
Wireless ISP
3
Outline
q Reconfigurable antenna system for WiFi devices
q Advantages and challenges of using reconfigurable antennas in commercial WiFi devices
l Network capacity maximization
l Interference mitigation
l Enhanced capacity in high density environments
l Coordination and benefit with digital beamforming
l Coordination and benefit with MU-MIMO
q Conclusions
4
Active RF devices shape the antenna beams and control their direction
PCB metamaterial antenna integrates easily into any device
Reconfigurable antenna system
SW algorithms select the optimal beam shape for
maximum reliability of the wireless link
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MIMO systems – adaptive antennas
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The best wireless communication channel between TX/RX antennas is carefully selected among the large set of channels that can be generated by changing the antenna radiation patterns
SINGLE CHANNEL
STANDARD MIMO SYSTEM MIMO SYSTEM WITH RECONFIGURABLE ANTENNAS
DIFFERENT CHANNELS
CHANNEL SELECTION
TX RX
Standard static antenna
TX RX
Reconfigurable antenna
maximize channel diversity + SNR at
receiver suppress interference enhance pre-coding
techniques
Reconfigurable HW conceptual design
q Passive metal elements can be connected or disconnected from a ground plane or connected and disconnected between each other to change the beam and null direction of the active element
q Adant patented smart antenna technology and designs allow for best radiation efficiency, good impedance matching and lowest cost
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Active antenna
Passive metallization
Reconfigurable antenna capabilities
q Each antenna in the array can generate up to 2N independentradiation patterns where N is the number of parasitic elements in the antenna
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2016-Q2 Adant Smart Antenna PortfolioAll designs are scalable to different form factors to fit Wi-Fi
base stations for indoor and outdoor applications
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Antennas with omnidirectional coverage
Antennas with sectorial coverage
Integration with WiFi systems
q Integration is designed to support packet by packet configuration switching
q Antenna system allows for ≤ 1 µsec switching time
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WiFi 3x3 device
CPUwith
reconfigurable antenna drivers
Antenna control circuitry
WiFichipset
GPIO
GPIO
DC bias line
ANT 1
ANT 2
ANT 3
Maximum diversity + SNR
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Q array configurations
Optimal antenna selection
TXRX
H1H2
HN
…
𝐶 = max log) 𝑑𝑒𝑡 𝑰 +𝑆𝑁𝑅2𝑁3
𝑯2𝑯2∗
y = H x + n
Configuration selection in WLAN devices
qNormally the channel matrix (𝑯)is not directly available in commercial WLAN devices
qThe problem of selecting the optimal smart antenna configuration can be separated in two steps:l Evaluating the cost function: access the required parameters and compute the value
l Smart Antenna training: optimizing the cost function
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Cost function in WLAN devices
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qCost function must be strongly correlated to the performance metric that needs to be optimized
Available parameters
Meaning
RSSI Strength of received signal per antenna
SR Packet success rate
rate Rate of data transmission(modulation and coding)
BW Bandwidth of operationPL Packet length
APSTA
DATA PACKET
ACK
Example of cost function (CF) for throughput (TP) optimization
𝐶𝐹 = 𝑓 𝑆𝑅,𝑅𝑆𝑆𝐼, 𝑟𝑎𝑡𝑒, 𝐵𝑊, 𝑃𝐿
𝜌 𝐶𝐹, 𝑇𝑃 ≥ 0.9
Test setup
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Old villa Concrete ground and ceiling
Harsh environment
Underground parking lotConcrete ground and ceiling Quasi LOS environment
q Downlink and uplink throughput is measured with an omnidirectional antenna and with a reconfigurable antenna using a 3x3 BS and 2x2 client
Measured Performance – single client
Data sample of 100 measurements
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Average TP impr.Downlink = 36%Uplink = 30%
Reconfigurable antenna system improvement vs static antenna system
40% of cases where gain > 35% in download;; (30%in upload)
Measured Performance – single client
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Performance benefit is max at low SNR
Throughput Improvement vs. internal omnidirectional antennas
5 GHzDOWNLINK UPLINK
ALL THROUGHPUT RANGES 1.36x 1.30x
HIGH THROUGHPUT(>60% of MAX THROUGHPUT)
1.15x 1.04x
LOW THROUGHPUT (<30% of MAX THROUGHPUT)
1.43x 1.34×
Measured Performance – multi client
Reconfigurable antenna system improvement vs static antenna system
Average TP improvement = 30%
Data sample of 44 measurements
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Reconfigurable antennas for interference mitigation
18
Q array configurations
Optimal antenna selection
TXRX
H1H2
HN
…
𝐶 = max log) 𝑑𝑒𝑡 𝑰 +𝑆𝑁𝑅2𝑁3
𝑯2𝑯2∗𝑾2
HI
Dynamically change direction of radiation to maximize power at the receiver while minimizing interference
Adant interference mitigation
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Interference test setup
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q Throughput in downlink is measured with an omnidirectional antenna and with a reconfigurable antenna using a 3x3 BS and 2x2 client
q Client (STA) is exposed to a lower amount of interference with respect to the AP
q Distance between AP and client is minimized to determine only the effect due to interference mitigation
d < 5 m
D > d
d < 5 m
D > d
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Measured Performance
Reconfigurable antenna system improvement vs static antenna system
20 different scenarios
Average TP improvement = 3.5X
High density deployment
AP 1 AP 3
AP 2 AP 46
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7
8
q Multiple APs operating on the same frequency channel
q Co-channel interference is main cause of performance degradation
q Reconfigurable antennas provides coordinated interference mitigation capabilities to improve the network capacity
22
Multiple base stations with implicit coordinationEach optimizes its own cost function with no coordination with the other base stations
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Figure.5.Aggregate)throughput)of)each)BSS,)total)per)deployment:)AP)tx)power)set)to)17dBm)
)We)repeated)a)very)similar)test)with)four)additional)deployments)targeted)to)analyzing)whether)SA)technology) may) address) the) coTchannel) interference) problem) also) with) higher) settings) of) the)transmission)power:)to)this)end)we)increased)the)transmission)power)of)ZyXEL)and)Ruckus)only)to)23dBm)keeping)the)others)to)17dBm.)This)should)increase)the)interference)between)the)two)BSSs)but)only)for)the)APs)equipped)with)SA)technology.))As)before)we)report)in)Figure)6)the)positions)of)the)clients)for)the)four)additional)deployments.)The)first)two,)3T1)and)3T2,)are)on)the)left;)the)others,)4T1)and)4T2,)are)on)the)right.)We)use)again)arrows)to)indicate)how)we)moved)nodes)from)one)deployment)to)the)next.)))
BSS1 BSS2 BSS1+BSS20
100
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Ag
gre
ga
te T
hro
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hp
ut
[Mb
/s]
Deployment 1−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
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[Mb
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Deployment 1−2
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
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[Mb
/s]
Deployment 2−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
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gre
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[Mb
/s]
Deployment 2−2
zyxelruckusciscoaruba
Figure.5.Aggregate)throughput)of)each)BSS,)total)per)deployment:)AP)tx)power)set)to)17dBm)
)We)repeated)a)very)similar)test)with)four)additional)deployments)targeted)to)analyzing)whether)SA)technology) may) address) the) coTchannel) interference) problem) also) with) higher) settings) of) the)transmission)power:)to)this)end)we)increased)the)transmission)power)of)ZyXEL)and)Ruckus)only)to)23dBm)keeping)the)others)to)17dBm.)This)should)increase)the)interference)between)the)two)BSSs)but)only)for)the)APs)equipped)with)SA)technology.))As)before)we)report)in)Figure)6)the)positions)of)the)clients)for)the)four)additional)deployments.)The)first)two,)3T1)and)3T2,)are)on)the)left;)the)others,)4T1)and)4T2,)are)on)the)right.)We)use)again)arrows)to)indicate)how)we)moved)nodes)from)one)deployment)to)the)next.)))
BSS1 BSS2 BSS1+BSS20
100
200
300
400
500
600
Ag
gre
ga
te T
hro
ug
hp
ut
[Mb
/s]
Deployment 1−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
100
200
300
400
500
600
700
Ag
gre
ga
te T
hro
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hp
ut
[Mb
/s]
Deployment 1−2
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
100
200
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400
500
600
Ag
gre
ga
te T
hro
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hp
ut
[Mb
/s]
Deployment 2−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
50
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350
Ag
gre
ga
te T
hro
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hp
ut
[Mb
/s]
Deployment 2−2
zyxelruckusciscoaruba
Figure.5.Aggregate)throughput)of)each)BSS,)total)per)deployment:)AP)tx)power)set)to)17dBm)
)We)repeated)a)very)similar)test)with)four)additional)deployments)targeted)to)analyzing)whether)SA)technology) may) address) the) coTchannel) interference) problem) also) with) higher) settings) of) the)transmission)power:)to)this)end)we)increased)the)transmission)power)of)ZyXEL)and)Ruckus)only)to)23dBm)keeping)the)others)to)17dBm.)This)should)increase)the)interference)between)the)two)BSSs)but)only)for)the)APs)equipped)with)SA)technology.))As)before)we)report)in)Figure)6)the)positions)of)the)clients)for)the)four)additional)deployments.)The)first)two,)3T1)and)3T2,)are)on)the)left;)the)others,)4T1)and)4T2,)are)on)the)right.)We)use)again)arrows)to)indicate)how)we)moved)nodes)from)one)deployment)to)the)next.)))
BSS1 BSS2 BSS1+BSS20
100
200
300
400
500
600
Aggre
gate
Thro
ughput [M
b/s
]
Deployment 1−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
100
200
300
400
500
600
700
Aggre
gate
Thro
ughput [M
b/s
]
Deployment 1−2
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
100
200
300
400
500
600
Aggre
gate
Thro
ughput [M
b/s
]
Deployment 2−1
zyxelruckusciscoaruba
BSS1 BSS2 BSS1+BSS20
50
100
150
200
250
300
350
Aggre
gate
Thro
ughput [M
b/s
]
Deployment 2−2
zyxelruckusciscoaruba
)Figure.4)Positions)of)the)clients)for)the)four)deployments)with)transmission)power)set)to)17dBm..
)
We) can) see) in) Table) 5) that) ZyXEL,) in) the) first) three) deployments,) boosts) the) total) aggregate)
throughput)from)a)+25,5%)minimum)to)a)+46,7%)maximum)with)respect)to)the)second)in)the)rank)
that)is)Cisco.)Only)in)the)fourth)deployment)Cisco)does)better)with)a)+14.6%)increase)with)respect)
to)ZyXEL)that)ranks)second.)Also)this)test)confirm)that)a)specific)SA)technology)could)really)make)
the)difference)in)reducing)coTchannel)interference.)
)
Table.5)Total)aggregate)throughput)per)deployment:)AP)tx)power)set)to)17dBm.
6 Aruba6 Cisco6 Ruckus6 6ZyXEL6Depl.61#16 317,81) 425,82) 402,09) 544,98)
Depl.61#26 314,20) 439,87) 385,11) 645,36)
Depl.62#16 303,57) 452,95) 385,74) 568,57)
Depl.62#26 268,44) 333,30) 237,88) 290,68)
)
We)also)report)in)Figure)5)the)details)with)the)aggregate)throughput)per)BSS:)the)winner)in)the)total)
throughput)competition)wins)also)in)each)of)the)BSS.)
))
6
5 7
1
8
2 4
3
AP#2
AP#1
6
5 7
4
3
AP#2
AP#1
6
5 7
8
1
2 4
3
8 7 2 1
)Figure.4)Positions)of)the)clients)for)the)four)deployments)with)transmission)power)set)to)17dBm..
)
We) can) see) in) Table) 5) that) ZyXEL,) in) the) first) three) deployments,) boosts) the) total) aggregate)
throughput)from)a)+25,5%)minimum)to)a)+46,7%)maximum)with)respect)to)the)second)in)the)rank)
that)is)Cisco.)Only)in)the)fourth)deployment)Cisco)does)better)with)a)+14.6%)increase)with)respect)
to)ZyXEL)that)ranks)second.)Also)this)test)confirm)that)a)specific)SA)technology)could)really)make)
the)difference)in)reducing)coTchannel)interference.)
)
Table.5)Total)aggregate)throughput)per)deployment:)AP)tx)power)set)to)17dBm.
6 Aruba6 Cisco6 Ruckus6 6ZyXEL6Depl.61#16 317,81) 425,82) 402,09) 544,98)
Depl.61#26 314,20) 439,87) 385,11) 645,36)
Depl.62#16 303,57) 452,95) 385,74) 568,57)
Depl.62#26 268,44) 333,30) 237,88) 290,68)
)
We)also)report)in)Figure)5)the)details)with)the)aggregate)throughput)per)BSS:)the)winner)in)the)total)
throughput)competition)wins)also)in)each)of)the)BSS.)
))
6
5 7
1
8
2 4
3
AP#2
AP#1
6
5 7
4
3
AP#2
AP#1
6
5 7
8
1
2 4
3
8 7 2 1
AP with Adant reconfigurable antenna system
Deployment 1 Deployment 2 Deployment 3
Deployment 3Deployment 1 and 2
Explicit coordination
24
A. Michaloliakos, W. C. Ao, and K. Psounis, “Joint user-beam selection for hybrid beamforming in asynchronously coordinated multi-cell networks”, in Proceedings of Information Theory and Applications Workshop (ITA), San Diego, California, USA, February 2016.
AP 1
AP 3
AP 2
AP 4
4
3
2
qJoint user-beam selection
AP 1 AP 3
AP 2
AP 46
47
8
Coordination schemes performance
8 20 400
10
20
30
40
50
60
Number of stations
Avg.
Thr
ough
put p
er u
ser [
Mbp
s]
SU−MISOMU−MIMOCoor. MU−Hybrid 1x PowerCoor. MU−Hybrid 2x PowerCoor. MU−Hybrid 8x PowerCoor. MU−MIMO
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AP density: 1 AP/BS per 112.5/45/22.5 sq m (~10/7/5m between APs/BSs) User density: 1 active user per 4.5 sq m(~10% of users active)
30x30m hall, 200 users,
A. Michaloliakos, W. C. Ao, and K. Psounis, “Joint user-beam selection for hybrid beamforming in asynchronously coordinated multi-cell networks”, in Proceedings of Information Theory and Applications Workshop (ITA), San Diego, California, USA, February 2016.
Smart antenna and digital beamforming
26
The reconfigurable antenna selects the best wirelesschannel and the precoding matrix optimizes thatchannel for maximum SNR at the receiver
Q array configurations
TXRX
H1H2
HN
…
Simply Better Wireless.
Page 2
Using All the Tools You Can
Since these RF fundamentals matter so much now to the
performance of your network, and to the experience of your
users, we’re ready to take up the challenge of getting you
enough knowledge to make good Wi-Fi network design
decisions nonetheless. To build the foundation in “how stuff
works” required to accurately assess claims and likely per-
formance benefits for multi-antenna systems, we’re going to
go back to the basics here, using lots of pictures and defin-
ing carefully the necessary jargon along the way to try to help
make things very clear.
We start with an old-fashioned single-antenna access point,
shown in Figure 1, with a common omni-directional antenna,
or an “omni”. When this device transmits, as the antenna’s
name suggests, it sends the same signal in all directions in the
horizontal plane (we’ll worry about what happens in the verti-
cal direction in section 4). While this approach has a certain
satisfying design simplicity, it has substantial performance
disadvantages. The vast majority of this radio energy is com-
pletely wasted, since an access point can only talk to one client
at a time. Beyond mere waste, this excess energy causes prob-
lems in the form of more self-interference in the WLAN, step-
ping on neighboring APs and their clients and reducing the
possibility of channel reuse nearby. Meanwhile, the tiny frac-
tion of transmit energy that actually reaches the client yields a
lower throughput rate, as we’ll show shortly, than would be the
case if the energy could be focused more tightly (since client
throughput is directly related to available signal strength).
Next we introduce another omni antenna to begin to explore
the options this might provide us for better control of the
radio signal. As shown in Figure 2, the combination of two
copies of the same signal transmitted from two neighbor-
ing omni antennas creates a set of intersecting troughs and
peaks, much like the wave rings you would get by tossing
two separate rocks into a still pond at the same time. In some
locations, the peaks of the signal from transmit antenna 1
(“Tx 1”, in the jargon) line up in space and time with the peaks
from Tx 2 — this is referred to as constructive combination. In
other locations, the peaks of Tx 1’s signal are lined up with the
troughs of signal from Tx 2, which yields destructive combina-tion. If a receive (Rx) antenna is placed in the zone of perfect
constructive combination, it would pick up roughly twice the
signal strength of a single Tx antenna’s output, without doing
any intelligent work on its own — its analog receive electron-
ics simply sum the signals received automatically. In contrast,
a zone of complete destructive combination would yield zero
FIGURE 1: Radio signal distribution pattern from an access point with one omni-directional antenna.
Omni Transmit (Tx)Pattern
FIGURE 2: Fundamental concepts in multi-antenna processing for increased signal strength (technology often broadly categorized as “beamforming”)
ConstructiveCombination
Tx Antenna 1
In Phase
180º Outof Phase
Tx Antenna 2
Time2x signal
Signal strength
ReceiveAntenna (Rx)
DestructiveCombination
No signalTx 1
Tx 2
Rx
Maximum signal strength at receiver and channel selection
y = H Bx
Smart antenna and digital beamformingOptimal combined radiation patterns to improve link of interest (power at receiver) and interference mitigation (null steering towards interfering sources)
27
Combined beamforming and reconfigurable antenna digital
beamforming only
Optimal control of radiation nulls and radiation in the intended direction
AP
Test setupDownlink throughput is measured with an omnidirectional antenna and with a reconfigurable antenna system using an AP with digital beamforming
28
Old villa Concrete ground and ceiling
Harsh environment
Underground parking lotConcrete ground and ceiling Quasi LOS environment
Measured Performance
40%
Data sample of 100 measurements29
25% of cases where gain >40%
Reconfigurable antenna system improvement vs static antenna system
Average TP impr. = 32%
Advantages of Adant and TXBF
Adant smart antenna system significantly improves AP performance with and without TXBF
30
Results based on >50 independent measurements in two different environments
Average benefit vs. standard antenna systemTXBF OFF TXBF ON
35% 32%
EXAMPLE Standard Omni Antennas
Adant smart antenna system
TXBF OFF 100 Mbps 135 MbpsTXBF ON 130 Mbps 170 Mbps
Reconfigurable antennas and MU-MIMO
31
The reconfigurable antenna creates the wirelesschannel to enable the possibility of simultaneoustransmission to multiple users through the properprecoding matrix
TXRX 1
H1H2
HN
…
RX 2
HNB2 = 0
HNB1 = 0
Grouping and reconfigurable antennas
Grouping OK Grouping NOT possible
Client A
Client B
Client C
Omnidirectionalradiation
Client A
Client B
Client C
Omnidirectional radiation
SCENARIO A SCENARIO B
Grouping OK Grouping OK
STANDARD ANTENNA
RECONFIGURABLE
ANTENNA Client A
Client B
Client C
Smart antenna configuration
AP
AP
AP
AP
Client A
Client B
Client C
Smart antenna configuration
32
Test setupqDifferent combinations of three MU-MIMO clients are connected to a 4x4 commercial grade AP MU-MIMO capable based on QCA 9990 chipset
qAggregate downlink throughput is measured with an omnidirectional antenna and with a reconfigurable antenna system
33
Data sample of >40 measurements
Measured Performance
34
45% of cases where gain >30%
Reconfigurable antenna system improvement vs static antenna system
Average TP improvement = 30%
ConclusionsqReconfigurable antenna systems significantly enhance WiFi networks by:l Maximizing network capacity l Mitigating interference through implicit or explicit coordination between base stations
l Enhancing based band pre-coding techniques like MU-MIMOqAntenna selection speed and uplink benefit highly depend on the level of integration that can be achieved with the WiFi chipset
qAdditional benefits that Adant is further exploring in using reconfigurable antennas in WiFinetworks are relative to the possibility of l Enhancing security of the networkl Providing reliable localization services
35