July 2015
doc.: IEEE 802.19-15/0055r3
Unlicensed LTE/WiFi Coexistence Testbed
Date: 2015-07-06
Authors:
Name
Affiliations
Ben Lampert
Akhila
Nandgopal
Submission
Address
Phone
email
octoScope
9712182444
octoScope
17745786774
Ben.Lampert@octoScope.
com
Akhila.Nandgopal@octoS
cope.com
Slide 1
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Abstract
Propose an Unlicensed-LTE/Wi-Fi testbed for coexistence
characterization.
Submission
Slide 2
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Common Testbed Motivation
• Everyone benefits from testing real devices and
applications that would be difficult to recreate in a
simulation
• Wi-Fi community will benefit from “hands on”
experience with Unlicensed LTE to evaluate their
applications and devices
• 3GPP will benefit by alleviating concerns about
coexistence mechanisms and using data to inform LTELAA decisions
• A neutral test platform can provide fair sharing data
for both Wi-Fi and Unlicensed LTE to help inform
decisions from both groups
Submission
Slide 3
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
LTE-LAA Benefits from Participating in
Testing
• Testbed will allow for any early LTE-LAA
development units to be tested (ie, rack mounted)
• Can use existing Wi-Fi/LTE-U devices to help drive
LTE-LAA decisions based on real interactions.
•
•
•
•
Best Coexistence Mechanisms
Energy detection thresholds
Real device traffic patterns and application behavior
Channel selection algorithms
• Good LTE-U Coexistence data already taken [1], input
from Wi-Fi community can only help inform decisions
Submission
Slide 4
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Possible Test Scenarios
• Testbed to define and validate fairness
• Wi-Fi/LTE, Wi-Fi/Wi-Fi, LTE/LTE
• Fairness criteria including
• VoIP, Packet Jitter, Airtime, Throughput, etc
• Neutral Testbed for vendors (LTE/Wi-Fi) to test
particular scenarios
•
•
•
•
•
Submission
Hidden Nodes
High Density Environments
Operation in different CCA detection thresholds
Application/vendor specific tests
Adjacent/Co-Channel Interference
Slide 5
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Intro to Unlicensed-LTE Testbed
• Goal was to design a RF environment that was flexible for testing
variety of Unlicensed LTE/LTE-LAA/LTE-U/Wi-Fi scenarios.
• Based on our understanding the requirements for a wireless
contention test bed are:
•
•
•
•
•
•
High Isolation from external devices
Good control over power levels across devices
Multipath Environment to test MIMO STA’s
Ability to test real applications (VoIP, Video streaming, file transfer, etc)
Flexibility to test high channel load environments
Repeatability and in a lab environment
• Focused on simple scenario:
• Wi-Fi AP-STA baseline with added Wi-Fi or LTE eNB traffic
Submission
Slide 6
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Ethernet, HDMI, USB Ports
Coexistence Testbed with multipath
LTE monitor
OTA
LTE UEs
Wi-Fi STAs
Wi-Fi sniffer
8
Multi-Path Emulation
802.11 AP
8
Attenuator
Wi-Fi
Ethernet
Attenuator
Ethernet
LTE
LTE eNB / Wi-Fi AP
Submission
Slide 7
Goals:
-OTA (Over the air) Coexistence
testing
-Multi Path Emulation (Can be
bypassed)
-Wi-Fi traffic to clients
benchmarked before and after
LTE introduced
-Wi-Fi sniffer helps diagnose
channel loading/packet timing
-Can be used to test real life
applications (video streaming,
VoIP, etc).
-Attenuation helps tune power
received on STA/UE.
-Can test two 4x4 Wi-Fi AP’s or a
4x4 Wi-Fi AP with a 2x2 LTE
device.
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Ethernet, HDMI, USB Ports
Coexistence Testbed w/o multipath
LTE monitor
Wi-Fi STAs
OTA
LTE UEs
Attenuator
Wi-Fi sniffer
6-8
802.11 AP
Ethernet
Ethernet
Goals:
-Similar to multipath testbed
-AP and eNB couple OTA in top
box via antennas.
Wi-Fi
4
LTE
2-4
LTE eNB
Submission
Slide 8
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Hidden Node Scenario
• One possible test scenario is characterizing how
Unlicensed-LTE and Wi-Fi handle hidden nodes
• When group 1,3 cannot directly observe each other or
observe below ED levels how will the detection
mechanisms work?
AP1/enB1
AP2/enB2
AP3/enB3
Clients1
Clients2
Clients3
Hidden Node problem:
Groups 1,2 and 2,3 can observe each other. But groups 1,3 cannot (outside of the Rx sensitivity)
Submission
Slide 9
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Multiple Nodes/Hidden Node Testbed
Client Box 2
Client Box 1
Attenuator
Wi-Fi/LTE Clients
Client Box 3
Attenuator
Attenuator
Wi-Fi/LTE Clients
Wi-Fi/LTE Clients
Wi-Fi
Wi-Fi
Wi-Fi
LTE
LTE
LTE
AP/eNB Box 1
Submission
AP/eNB Box 2
Slide 10
AP/eNB Box 3
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Hidden Node Configuration
5Ghz Path Loss
Attenuator Client-Client
Attenuator AP-Client
Cables
OTA Loss
Tx Power
Rx Threshold
Est. Rx
6 Power
6 (dBm)
3 C1 Tx
40 C2 Tx
+24dBm C3 Tx
>-100dBm AP1 Tx
AP2 Tx
AP3 Tx
C1 Rx
-65
-111
-25
-71
-117
C2 Rx
-65
-65
-71
-25
-71
C3 Rx
-111
-65
-117
-71
-25
AP1 Rx AP2 Rx AP3 Rx
-25
-71
-117
-71
-25
-71
-117
-71
-25
-77
-123
-77
-77
-123
-77
-
• Clients and AP/eNB in Box 2 see both C1/AP1 and C3/AP3
• Devices in 1 and 3 cannot observed each other (outside of
the Rx Sensitivity)
• Link between 1/3 can be added depending on scenario.
Submission
Slide 11
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Extra Slides
Submission
Slide 12
Ben Lampert, octoScope
Ethernet, HDMI, USB Ports
July 2015
doc.: IEEE 802.19-15/0055r3
Rack Mount Testing
•
LTE monitor
OTA
Attenuator
•
Wi-Fi STAs
LTE UEs
Wi-Fi sniffer
6
802.11 AP
Wi-Fi
et
4
net
Option 1: Rack inside chamber
LTE eNB (Rack mounted)
Submission
2
2
Slide 13
Ideally would like to put in
the chamber to maximize
isolation, but this may not
be an option.
Rackmount RF shielding
may also be poor, so may
consider putting enB in it’s
own box to reduce
leakage.
Option 2: Rack outside of
chamber
LTE eNB (Rack mounted)
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Multiple Small Cell Testbed
LTE-U Indoor Simulation Scenarios (SI5-8)
-Based on test scenarios provided by 3GPP (See 2)
-Chaining chambers expands wireless loading/environment
-Multiple AP’s, Small Cells operating co-channel
1
2
3
n
Length = 120 m
2
3
n
15 m
Width = 50 m
1
Links between nodes control interactions
15 m
Operator 1 Small Cell
Operator 2 Small Cell
Private WiFi AP
Submission
Slide 14
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
Possible Multiple Small Cell/Enterprise
loading configuration
RF daisy-chain coupling to emulate space among AP/eNB pairs
Submission
Slide 15
Ben Lampert, octoScope
July 2015
doc.: IEEE 802.19-15/0055r3
References
[1] LTE-U Technology and Coexistence, LTE-U Forum
May 28th, 2015
http://www.lteuforum.org/uploads/3/5/6/8/3568127/lteu_coexistence_mechansim_qualcomm_may_28_2015.p
df
[2] LTE-LAA 3GPP Document 36.889-011
Submission
Slide 16
Ben Lampert, octoScope