octoBox stackable anechoic wireless testbed
53
[email protected] June 2014
-
Upload
fanny-mlinarsky -
Category
Devices & Hardware
-
view
165 -
download
20
description
octoBox is a stackable small anechoic testbed used for testing wireless throughput, including throughput of high order MIMO systems such as 802.11ac and LTE, range, data rate adaptation, roaming, mesh, DSRC , etc. Video at https://www.youtube.com/watch?v=QIaL7SFZpx4&feature=youtu.be
Transcript of octoBox stackable anechoic wireless testbed
June 2014
www.octoscope.com
Watch video at this link:https://www.youtube.com/watch?v=QIaL7SFZpx4
OB-38-TT Turntable octoBox
3
www.octoscope.com
octoBox Stackable - Summary
• Modern design optimized for
wireless test applications
• Stable and repeatable over-
the-air coupling for testing
devices with internal
antennas
• 700 MHz to 6 GHz
• Easy interconnections
among multiple boxes and
multiple stacks
5
www.octoscope.com
octoBox
Configurations
OB-26 quadStack
OB-26 anechoic chamber
MPE (Multipath emulator)
OB-38 MPE Stack
6
www.octoscope.com
octoBox Wireless Testbeds
• octoBox testbeds ship
assembled and ready to
us in a crate
• The crate door also
acts as a ramp, making
it easy to wheel the
system out and get
started
7
www.octoscope.com
octoBox quadStack and triStack Dimensions
octoBox-38 triStackoctoBox-26 quadStack
38.35”
24”
31.2”
42” 30.5”
26.35”
18”
25.2”
34”28.5”
6’6”
8
www.octoscope.com
octoBox External and Internal DimensionsoctoBox-38 (OB-38)octoBox-26 (OB-26)
38.35”
24”
31.2”26.35”
18”
25.2”
9
www.octoscope.com
Optional RF Modules
Two modules can be stacked
(shown mounted on OB-38)
4 programmable RF attenuators
individually controllable and powered
via a single USB or Ethernet/PoE
connection
10
www.octoscope.com
Attenuator and Waveform Generator Modules
Modules easily mount on the
side of octoBox for construction
of flexible testbeds.
Unsurpassed isolation
USB and Ethernet/POE ports are
filtered to avoid data cables from
acting as antennas and bringing
interference into the testbed.
11
www.octoscope.com
quadAtten/waveGen Module Dimensions
9.5” (24 cm)
1.5”
(3.8 cm)
3.9”
(9.9 cm)
12
www.octoscope.com
Isolation and Filtering
• Creating controlled RF conditions with good
isolation is challenging, particularly for
large-scale RF test setups, such as mesh
configurations.
Short wavelength high frequency signals
couple via many paths, including copper
cabling, poor/aging gasketing, ground loops,
etc. Sources of interference may be difficult
to locate in a multi-box setup.
• Isolation considerations
Isolation should be measured and specified
with a fully cabled test setup.
All copper cabling, including Ethernet and
power cabling, will act as antennas
contributing to RF coupling among enclosures
and thus limiting attenuation range setting.
Upfront investment into high grade
enclosures with good data and power feed-
through filtering and absorptive foam can
save 1-2 months of chasing uncontrolled
paths of interference in the test setup.
octoBox modular feed-through high speed data filters
Fits up to 4 filters
13
www.octoscope.com
Single Box Shipping Package
Rubber feet assembly
AC Power
entry
Fan
Filter inputs
14
www.octoscope.com
octoBox-26 Internal View
GPS antenna
Wi-Fi
antenna
Cellular
antenna
Filtered
Ethernet
Filtered
USB
DUT shelf13.35”
Plastic rails and shelf
15
www.octoscope.com
Filtered Data Ports
Filters include:Gig Ethernet / POE
USB
HDMI
DC power
AC power and
vents are also
filtered
Removable
sections of
gradient
absorber
provide easy
access to
connectors
16
www.octoscope.com
8 Individually Controlled RF Ports
2 quadAtten modules individually control power
of the 8 RF signals entering the octoBox
4x4 MIMO signal
Interference
quadAtten
(2 stacked modules)
18
www.octoscope.com
octoBox Anechoic Conditions; Plastic Rails
RF-transparent plastic rails
Hide cabling behind
absorber for neat set-up
19
www.octoscope.com
OB-26-TT Internal View - Smartphone Antennas
Multiband
cellular
Wi-FiMultiband
GPS
Anechoic turntable construction –
Only plastic parts penetrate absorber lining
Filtered Ethernet
and USB
20
www.octoscope.com
Multipath Emulator
• Wi-Fi manufacturers and evaluators test throughput performance in
open air ‘real-life’ environment (e.g. a typical house or office) or using
channel emulators.
• octoScope has developed an octoBox based testbed that creates
multipath closely approaching the IEEE 802.11n/ac Models B or C,
emulating home and small office environment.
• octoBox MPE (multipath emulator) creates multipath inside octoBox
small anechoic chamber by generating reflections with stubs of coaxial
cable. A quad multipath emulator fixture supports up to 4-stream
MIMO.
• octoBox-MPE has been simulated, prototyped, measured and
compared to the IEEE models.
• Data throughput tests have been performed by
www.smallnetbuilder.com on a 2x2 and a 3x3 802.11ac MIMO
configuration demonstrating MIMO gains inside octoBox with
equivalent or higher throughput to that measured in a representative
home environment.
• See SmallNetBuilder.com test results at this link:
http://www.smallnetbuilder.com/wireless/wireless-howto/32082-how-we-test-
wireless-products-revison-7
octoBox-MPE module (stacked in the
middle) emulates IEEE 802.11n/ac
Models B or C corresponding to home
and small office environment.
Patents pending
22
www.octoscope.com
octoBox-MPE MIMO OTA Testbed Diagram
OTA = over the air
DUT AP
Test Antennas
Traffic
TX/RX
Remote
Desktop
Multipath Emulator
Master client
quadAtten
octoBox
23
www.octoscope.com
Internal View of Antenna MountingMIMO antenna spacing controls correlation
25
www.octoscope.com
Background
MPE Frequency Response
2.4 GHz band
5 GHz band
MPE (Multipath emulator)
26
www.octoscope.com
octoBox-MPE vs. IEEE Model B (House Model)Model B 0ns 10 ns 20ns 30ns 40ns 50ns 60ns 70ns 80ns
Cluster 1 0 -5.4 -10.8 -16.2 -21.7
Cluster 2 -3.2 -6.3 -9.4 -12.5 -15.6 -18.7 -21.8
Time domain response obtained from measured frequency domain
27
www.octoscope.com
Automated MIMO Throughput vs. Range Test
0
50
100
150
200
250
300
350
400
0 10 20 30 40 50 60
Th
rou
gh
pu
t (M
bp
s)
Attenuation Setting (dB)
TCP Throughput
Measured using octoBox MPE testbed using automated throughput script - early 802.11ac device
http://www.octoscope.com/English/Products/octoBox_MPE/octoBox_MPE.html
Multiple points can be measured
Repeatable controlled environment
Measurement process is automated
Script controls IxChariot and programmable attenuators, outputs Excel plot
OB-38 MPE Stack
MPE
MPE = multi path emulator
28
www.octoscope.com
octoBox-TT (Turntable) Plot
0
20
40
60
80
100
120
140
160
180
200-180
-165
-150
-135
-120
-105
-90
-75
-60
-45
-30
-150
15
30
45
60
75
90
105
120
135
150
165
Throughput vs. rotation angle
0dB (Mbps)
5dB (Mbps)
10dB (Mbps)
15dB (Mbps)
20dB (Mbps)
25dB (Mbps)
30dB (Mbps)
40dB (Mbps)
45dB (Mbps)
50dB (Mbps)
55dB (Mbps)
60dB (Mbps)
Mbps
29
www.octoscope.com
Antenna Mounting System
What’s important for near-field
metrics is OTA coupling stability.
octoBox antenna mounting system
octoBox offers unparalleled flexibility in mounting
test antennas for OTA coupling stability. And it also
enables simultaneous measurements of multiple
radios in the DUT.
30
www.octoscope.com
octoBox Antenna Arrangement for Smartphones
Dual-band Wi-Fi/Bluetooth Antenna
More antennas can be added for MIMO testing
GPS antenna
1573.42; 1575.42; 1577.42 MHz
2G/3G/LTE antenna
octoBox plastic rail
and DUT shelf
system
iPhone DUT
704-787 MHz
824-960 MHz
1575.42 MHz
1710-1990 MHz
2110-2170 MHz
2496-2700 MHz
This configuration supports the iPhone and most other smartphones and pads on the market
31
www.octoscope.com
Isolation and Absorption• Superior isolation and absorption support over the
air coupling and ensure robust operating margin for
conducted coupling of RF signal
• Isolation
Allows accurate path loss setting
Prevents errors caused by ambient noise and crosstalk
• Absorption
>20 dB achieved using gradient absorptive foam
Eliminates standing waves that cause nulls in the
signal
Improves overall isolation of the enclosure
Standing waves create fluctuations in the signal
Dual gasketing and
right angle door
seals
2.25” gradient
absorptive foam covers
inside surfacesGradient absorber
matches
impedance of metal
to air
32
www.octoscope.com
Controlled Environment Test
Ethernet
Programmable attenuator
RF isolation box
USB
Feed-through filters
Distance and motion emulated using a programmable attenuator to model path loss (flat fading) or a channel emulator to model multipath and Doppler fading
Signal coupled via cabling (conducted) or over the air (OTA)
Master and DUT are isolated from each other to achieve wide dynamic range of the measurement by eliminating crosstalk
octoBox-26 small anechoic chamber
33
www.octoscope.com
Controlled
Environment
Measurement
Example
Noise, interference and Master to DUT coupling must be well below intended signal level at DUT for metrics such as rate/MCS adaptation or roaming performance
Wi-Fi DUT’s data rate adaptation
behavior vs. RSSI all the way down
to the RSSI level of -95 dBm.
Measured DUT RSSI is less than
-95 dBm. This means Master to
DUT coupling of less than -100 dBm.
802.11b (DSSS-CCK)– 1, 2, 5.5, 11 Mbps; 2.4 GHz
802.11a (OFDM)– 6, 9, 12, 18, 24, 36, 48, 54 Mbps; 5 GHz
802.11g– both 11b and 11a rates; 2.4 GHz
802.11n– up to 600 Mbps; 2.4 and 5 GHz
Data rate adaptationvs.
RSSI
MCS = modulation coding schemeDUT = device under test
34
www.octoscope.com
Basic Radio Performance Tests
• RX sensitivity
• TX spectrum, EVM
• Range
• Adaptive Modulation
• Roaming behavior
• Performance in the
presence of noise and
interference
Noise/interference generator
DUT = device under testEVM = error vector magnitude
RF combiner
Variable RF attenuator
Master
DUT
Isolation box
35
www.octoscope.com
octoBox Roaming Test Configuration
USB
Controller or
Ethernet switch
Client/bridge
under test
Traffic
source/sink
1:4 RF combiner
octoBox-26 Stackable
Traffic
source/sink
AP2
AP1
octoBox-26 Stackable
RF attenuators
Feed-through
Ethernet filters
RF port
ATTEN1
Eth
ern
et
Spare combiner ports for
connecting a sniffer
ATTEN2
37
www.octoscope.com
octoBox Roaming Test Script
Programmable
attenuator ramp
Ping request-
response delay
Connection outage due to roaming
38
www.octoscope.com
Roaming Results - Details from Sniffer
3.16 sec
9.04 sec
6.63 sec
0
5
10
15
20
25
30
35
40
45
50
0 2 4 6 8 10 12 14
dB
ab
ove
no
ise
Seconds
RSSI 61:30
RSSI 5a:f0
ping requests
ping replies
deassociate
deauthenticate
authenticate
assoc req-resp
Last ping response: 3.16 sec
Association: 6.63 sec
First ping response: 9.04 sec
Wireshark
Sniffer
AirPcap Nx
USB dongles
39
www.octoscope.com
Wireless Mesh Testing
Wireless Mesh Metrics
• Self-healing, self-forming
• Throughput, QoS vs. hops
• Throughput, QoS vs. range
• Routing efficiency
• Dealing with interference
Multi-radio mesh nodes can communicate on
different channels with multiple neighbors
simultaneously.
In a single-channel mesh throughput is cut in half
at each hop.
41
www.octoscope.com
Wireless Mesh Test Configuration
Maximize attenuators to force auto-re-
routing of traffic flow to test self-healing
Fixed attenuators to set traffic
flow via one branch or another
to test self configuration
1
Nodes are in octoBox
isolation chambers
octoBox quadStack
isolation enclosures with
built-in RF combiners
and attenuators
RF splitters used to direct
signal to multiple
neighboring devices
42
www.octoscope.com
Wireless Mesh Testing - Example
RF CombinerRF Switch
RF Attenuator
Antenna
octoBox upper chamber
#1octoBox lower chamber
#3
94:39:e5:01:3d:62 94:39:e5:01:68:ed
bc:77:37:ab:33:5d
PC in open air
#2
bc:77:37:ab:33:5d
94:39:e5:01:3d:62 94:39:e5:01:68:ed
octoBox
Console
US
B c
able
goi
ng th
roug
h da
ta fi
lter
to c
ontr
ol P
ingb
last
er r
unni
ng o
n #
3
Ping request -
response traffic
#2
#3
#1
#1
#2
#3
43
www.octoscope.com
Delay Through Mesh
~ 2 msec delay
One hop
Seconds
Ping round trip delay (ms)
~ 12 msec delay with
bursts of long delays
(>1 seconds)
Zero hops
bc:77:37:ab:33:5d
94:39:e5:01:3d:62 94:39:e5:01:68:ed
bc:77:37:ab:33:5d
94:39:e5:01:3d:62 94:39:e5:01:68:ed
BATMAN = better approach to mobile
ad hoc networking
44
www.octoscope.com
Connected Car DSRC Test
DSRC = direct short range communications
45
www.octoscope.com
Connected Car Testbed – Large Intersection
Emulate groups of connected vehicles traveling over a busy highway interchange
46
www.octoscope.com
Example Large-scale DSRC Testbed
DSRC testbed emulates motion
of groups of cars with respect to
other groups
8-port
wireless
channel
emulator
Motion
Multipath
Noise
Up to 24 radio modules
in each chamber
192 radios in the testbed
octoBox quadStack
47
www.octoscope.com
Example: 3” x 5” x 1” DSRC DUT
DUTs
Layers of absorptive foam (not shown) separating DUTs
horizontally and vertically providing 10 dB of isolation per layer
Ethernet hubTest antennas
DSRC = direct short range communications
48
www.octoscope.com
Channel Emulator to Emulate Road
Sig
nal a
mpl
itude
at c
ar 2
Time
Car 1
Car 2
Wireless channel
emulator
Car 1
radio
Car 2
radio
Multipath fading
Shadow fading
Doppler fading Slow shadow fade due
to truck passing
through signal path
between 2 cars
g
octoBox RF
anechoic
chambers
49
www.octoscope.com
Specifications
Feature Specification
AC power entry module IEC-320 C14 inlet connector
120/240VAC 50/60Hz with 6A 5x20mm fuse
Cooling 80mm square axial fan
Filters over inlet and outlet for isolation
Filtered high speed data
connections
gigEthernet (with PoE), USB, HDMI, DB9, DB25 or DC
power ports
RF ports 8 RF barrel connector ports
Isolation >80 dB, fully cabled setup, up to 6 GHz
Absorption >20 dB from 1.3 to 40 GHz;
>15 dB down to 700 MHz
50
www.octoscope.com
Dimensions and Weight
American Metric
Outside:
18”H x 26.35”W x 25.2”D (-26 model)
24” H x 38.35”W x 31.2”D (-38 model)
Inside:
13.35”H x 19.35”W x 13.35”D (-26 model)
19.35”H x 31.5”W x 21. 5”D (-38 model)
Weight:
95 LBS (-26 model)
172 LBS (-38 model)
Outside:
45.7cm H x 67cm W x 64cm D (-26)
61cm H x 97 cm W x 79cm D (-38)
Inside:
34cm H x 49cm W x 34cm D (-26)
49cm H x 80cm W x 54.6cm D (-38)
Weight:
43 kg (-26 model)
78 kg (-38 model)
7 cm antenna length
Queenstar QWH-VPRR00
51
www.octoscope.com
octoBox Testbed SummaryOver the air coupling
Realistic environment
- Multipath
- Path loss
- Interference
Robust stackable design
Wheels for easy moving
Filtered vents for cooling
Filtered data ports
- Gig Ethernet/PoE
- USB
- HDMI
- AC and DC power
RF attenuators and
interference sources
controlled and powered
via filtered Ethernet or
USB for easy and neat
testbed construction
Multipath emulator
52
www.octoscope.com
Thank you!
• View octoBox information
• http://www.octoscope.com/English/Products/octoBox_MPE/octoBox_MPE.html
• View our publications, including articles, white papers, test reports and online tutorials
• http://www.octoscope.com/English/Resources/Articles.html
• Contact
+1.978.222.3114
53
