Cognitive Radio is dead…
Long live Cognitive Radio!
Arturas Medeisis, COST-TERRA Chair &
Oliver Holland, COST-TERRA Vice-Chair
Presentation at WP5A Workshop
Geneva, 18 November 2013
CR dead or alive?
 The CR concept was so much overhyped that for
some time now, one could feel a certain gloom in
the industry about the state and future prospects
of CR
 We believe what was overhyped is really an
expectation that CR will offer a disruptive
innovative leap overnight – that idea is as good as
dead
 Meanwhile CR is alive and well, and gradually
advances into radiocommunications market via a
plethora of incremental innovations
CR as part of future horizons
Outgoing wireless
technologies
(2G, 3G)
Emerging wireless
technologies
(4G, pre-CR)
Future wireless
technologies
(5G, CR)
The turbulence area:
past colliding with future,
producing interim
incremental adjustments of
technology
Pockets of the
future found in
the present
Today
Tomorrow
Future
Ref. three horizons framework by Sharp, Curry, Hodgson
But what is CR?
 The definitions many and vary widely
 The “philosopher’s stone” of our industry, which
presents itself differently depending on who looks
into it
 So to understand the CR we really need to start
with its definition, or rather the entire breadth of
implementation examples and development paths
of this complex concept…
CR implementation paths
Dynamic
Spectrum Access
Cognitive
Radio
Wireless
network
management
User-aware
wireless services
Heterogeneous
networking
Real-time spectrum auctions (lease)
Opportunistic exploitation of spectrum
“Advanced” commons, “underlay”
Self-provided
Managed
Geo-DB
CPC
Coverage expansion, ad hoc, mesh nets
RAN congestion mngmnt, capacity
enhancement
Self-organisation (reconfig/updates)
Energy saving, “Green” network
User as 8th OSI layer (QoS → QoI)
Location aware multimedia (social nets)
Sentient spaces (assisted living, robotics)
Terminal-centric multi-RAT access
Network-driven multi-RAT access
“On-the-fly” addition of new RATs
Ref. A. Medeisis et al (2012)
CR technology path
Level IV:
Re-orientation
Level III:
Learning
Level II:
Radio parameter
adaptation
Level I:
Radio
information
detection
© A. Medeisis et al (2012)
So the CR is already here
 In some applications, such as:
 Wireless network management applications
 User-aware wireless services
 Heterogeneous networking
 And growing from the lowest technological levels
towards the highest
 So the CR is alive, well, and growing, but how do
we make it more pervasive?...
 The following shows some examples considered in
COST-TERRA for progression of CR technologies
Physical layer
 Modulation advances - FBMC vs OFDM:
 High spectral containment, reduced side lobes
 No Cyclic Prefix, increased spectral efficiency
 Increased robustness
14
 When used in CR scenarios
12
10
Capacity (Bit/Hz/sec)
FBMC may provide
significant boost of radio
links resilience
and capacity
Optimal-OFDM
PI-OFDM
Zhang-OFDM
Optimal-FBMC
PI-FBMC
Zhang-FBMC
8
6
4
2
0
0.2
0.4
0.6
0.8
1
1.2
Ith-Watt
1.4
1.6
Low Interference
1.8
2
-5
x 10
© C. F. Bader (2013), Y. Zhang (2008)
MAC: time for ISM-Advanced?
 Commons become increasingly important,
including for mobile network traffic off-loading
 ISM-Advanced concept:
 Increased spectrum use efficiency
 Better throughput & stability
 Waving EIRP limit
 Studied means:
 Improved MAC protocols
 Smart Antennas
 Cooperative sensing/REM
 Game-theoretical approaches
© J. Sydor et al (2013), A. Medeisis et al (2014)
Adaptive channel access
 Water Filling Method, well known in the DSL
world
 Allows to better exploit the varying channel
characteristics:
 Optimising Tx power
consumption
 Maximising throughput
 Improved co-existence
© M. Bellanger (2012)
Radio Environment Mapping
 Essential platform for developing environmentally
aware, robust CR systems:
 White Space Devices
 Authorised Shared Access
 Self-Organised Networks
 Etc.
© J. Sydor (2011)
Interference management
 “Pluralistic Licensing” - an adaptable balance of interference
management
Licenceexempt
Lightlicensing
Pluralistic
licensing
more
interference
e.g., registration
e.g. ISM,
short range with regulator, low
power in-building
devices
GSM using DECT
bands
less
interference
Authorised
shared
access
e.g., mobile
broadband/
2.3GHz
Exclusive
e.g.,
GSM/LTE
 Primary interference and license fee based on primary/secondary services
Interference
Dual-priority broadband
License fee
Primary broadcast; secondary
mobile broadband services
PL: technical details
 Proactive primary mechanisms and pricing
Burden on primary
License fee
Beacon messages sent by
primary to ward off secondary
Primary registered in
geolocation database only
 Possible pricing example for secondary (relevant to secondary-secondary
coexistence; could be relevant also to primary-secondary)
Burden on secondary
High quality sensing
(e.g., feature detection),
for secondary politeness
Fee paid by secondary
Low quality sensing
(e.g., energy detection)
No sensing (only refers
to geolocation database)
© O. Holland et al (2012)
Conclusions
 Cognitive Radio is a complex term hiding many
nascent wireless technologies, and rumours of it’s
death had been greatly exaggerated
 The regulatory establishment could greatly help the
pace of technological innovation by creating
favourable conditions that would be conducive to CR
development and use
References
 COST Action IC0905 TERRA: www.cost-terra.org
 Sources of material reflected in this presentation:
 Y. Zhang, “Resource allocation for OFDM-Based cognitive radio systems,”
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Ph.D. dissertation, Univ. of British Columbia, Vancouver, December 2008;
C. F. Bader, “New Opportunities for Spectrum Sharing and Cognitive
Radio”, COST-TERRA, April 2013;
J. Sydor, “Report from Special Interest Group on ISM-Advanced”, COSTTERRA, April 2013;
M. Bellanger, “Exploitation of DSL systems spectral efficiency for the
benefit of CR and coexistence”, COST-TERRA, November 2012;
O. Holland et al, “Pluralistic licensing”, DySPAN’12, October 2012
A. Medeisis et al, “Taxonomy of Cognitive Radio applications”, DySPAN’12,
October 2012.
A. Medeisis et al, “ISM-Advanced: Improved Access Rules for Unlicensed
Spectrum”, submitted to DySPAN’14, April 2014