Cognitive radio presentation delivered at MobiCom 2011, the Annual International Conference on Mobile Computing and Networking.

1. “Cognitive Radio
Solutions:
Moving Beyond DSA”
MobiCom 2011
Rick Rotondo, xG Technology
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 1
www.xgtechnology.com

2. Cognitive Technology
► Cognitive radio is a paradigm for wireless
communication in which either a network or a
wireless node changes its transmission or reception
parameters to communicate efficiently avoiding
interference with licensed or unlicensed users.
Cognitive techniques have been almost exclusively focused
on DSA (running away from interference)
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 2
www.xgtechnology.com

3. White Spaces?
White Spaces
Is there such a thing as
Active Jamming – Black Spaces
White Spaces???
No! it is all gray space to
some degree
(or worse!) Heavy use – Dark Gray Spaces
Average Use – Light Gray Spaces
Getting
TIME
Very Light Use – Off-White Spaces hard to
find…
Unused Spectrum – White Spaces
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 3
www.xgtechnology.com

4. Traditional view of Cognitive Radios
► Able to identify spectrum that is not being used
► Dynamically tunes to those frequencies (within 30 ms)
► Instantly find other spectrum if interference is detected
► Adapt power, modulation, channel plan, network protocol, etc.
► Dynamically maximize throughput (or range) and minimize
interference to other devices
The Focus on running away from interference (DSA) does a
poor job of optimizing all available spectrum resources i.e.
Gray/Black Spaces
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 4
www.xgtechnology.com

5. xG’s take on Cognitive Radios
► Able to identify spectrum that is not being fully used
► Dynamically tunes to those frequencies (within 30 ms)
► Mitigate interference to the extent possible to extend “dwell
time” on the current frequency
► Employ DSA techniques if interference is overwhelming and
performance falls below set thresholds
► Adapt power, modulation, channel plan, network protocol, etc.
► Dynamically maximize throughput (or range) and minimize
interference
xG radios dynamically optimize spectrum utilization
through use of all available spectrum resources
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 5
www.xgtechnology.com

6. xMax Cognitive Technology
xMax Layered Cognitive Approach:
– Spectrum sensing: Interference based detection of transmitters.
– Spatial processing: MIMO technologies allow resistance to interferers.
Optimize SNR using multiple antenna processing.
– Spectrum sharing: Able to operate in crowed shared spectrum (ISM
UNI II etc.). Detect interferers, mitigate them, or avoid them by changing
operating parameters or frequencies.
– Spectrum management: Capture the most available spectrum.
Terminals and Base Station can change operating frequencies
dynamically.
– Spectrum mobility: Use spectrum dynamically. Mobile user stations
and base stations can decide to change bands where they operate.
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 6
www.xgtechnology.com

7. xMax Interference Processing
► Dependably operate on “gray and black spaces”
► Mitigate narrow/wideband, burst/continuous interference.
Short bursts of tens/hundred of microseconds typical to
cordless phones and other frequency hoppers are
removed by identifying the location of error in the time
T
domain and applying xMax adaptive interference error
I
correction.
M
E Longer bursts of several hundred microseconds and
longer are removed by spatial multi-antenna, multi-
algorithm error processing.
Frequency
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 7
www.xgtechnology.com

8. xMax Interference Processing
► Spatial processing to remove interference.
• xMax samples the arriving RF wave
front using 4 antennas.
• Interferers can be located by position
• Algorithms can be used in the receive
chain to mitigate this energy
• The xMax system sends known
training signals that are measured
and used to calibrate the receivers
xMax
• Spatial processing removes
interference that is longer than 800
microseconds.
• Shorter interference is removed by
redundant coding.
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 8
www.xgtechnology.com

9. xMax Interference Processing
► Multi-layer interference mitigation system.
Select
correctly
decoded
data
based on
Receiver algorithm 3
CRC.
Receiver algorithm 1 (Time diversity,
(MRC) nonlinear combining)
Receiver algorithm 2 Receiver algorithm 3
(Spacial projection) (Time diversity,
nonlinear combining)
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 9
www.xgtechnology.com

10. xMax Interference Processing
► Redundant coding to remove burst interference.
Data is Interference randomly Error free symbols
Transmitted destroys OFDM symbols. are identified
twice.
Error free version
is reassembled
How do we know what pieces of a received signal are
erroneous before error correction coding and CRC?
With 20 redundant pieces there are 1048576 possible
ways to assemble them. Not feasible unless we can
identify interference symbol by symbol.
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 10
www.xgtechnology.com

11. xMax Interference Processing
► How do we tell what received bits are interfered with?
(If we know exactly what bits are wrong we could just
invert them!)
6
x 10
1.8
80µs error burst. 1.6
1.4
xMax calculates estimate of OFDM 1.2
symbol being interfered based on statistics 1
computed for the whole data packet. 0 20 40 60 80 100 120
6
x 10
2
By computing statistics for two redundant
packets the system can assemble an error 1.5
free packet. It is like an error correction
1
coder on top of error correction coder telling
what pieces of the signal the coder should use. 0.5
0 20 40 60 80 100 120
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 11
www.xgtechnology.com

12. xMax Interference Processing
Simulation Results
7
6
5
4
3 1.5
2 1
0.5
1
0
0 10 20 30 40 50 60 70 80 90 100
0
0 10 20 30 40 50 60 70 80 90 100
1.4 MHz wide xMax with GSM- 1.4 MHz wide xMax signal after
like jammer. Spatial processing.
Xmax OFDM BER 0
Xmax OFDM BER
0
10 10
-1
-1 10
10
-2 -2
10 10
BER
-3
BER
-3
10 10
BPSK
-4 QPSK -4 BPSK
10 10
16QAM QPSK
64QAM 16QAM
-5 THEOR. 16QAM -5 64QAM
10 10
THEOR. QPSK THEOR. 16QAM
THEOR. QPSK
-6 -6
10 10
-4 -2 0 2 4 6 8 10 12 14 -4 -2 0 2 4 6 8 10 12 14
SNR SNR
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 12
www.xgtechnology.com

13. xMax Overview
VoIP CORE
POTS calling
SMS service
xMax Wireless Network xMSC
Public or
Private
Internet
Wi-Fi
Network SMS
server
xMod is a mobile xMSC has COTs
seamless bridge equipment for
between WiFi and xAPs provide wired network
Smart Phones, xMax networks network to xMax management,
Laptops or any network conversion. firewall , SIP
device with WiFi They can be vehicle Proxy, and SMS
can connect to the or tower mounted. server
xMod xAPs are Ethernet IP
connected.
WiFi Network xMax Cognitive Radio Network (C-RAN) Core Network Public Network
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 13
www.xgtechnology.com

14. Beyond DSA Summary
► Dynamic Spectrum Access (DSA) is a key aspect of CR
► But Cognitive Networks Must Leverage More Than DSA!
– Parallel Receiver Processing Chains (MIMO)
– Interference Mitigation Algorithms
– Adaptive Antennas, Beam Forming
– Adaptive Architecture (Point to Multipoint, Mesh, etc.)
– Application Aware QoS (VoIP, Throughput, Latency, Priority)
– Automatic & Dynamic Channel Planning
– Intelligent Modulation Adaptation
– Real-time Link Optimization
– Transmit Power Adjustment
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 14
www.xgtechnology.com

15. Thank You
The information presented herein is confidential and subject to change without notice. xG® and xMax® are
registered trademarks of xG Technology, Inc. Copyright 2010, All Rights Reserved. 15
www.xgtechnology.com