Cooperative MIMO Paradigms for Cognitive Radio Networks

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Dr. Liang Hong LHONG_at_TNstate.edu (615)
963-5364
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
Wei Chen Liang Hong College of
Engineering Tennessee State University
APDCM 2013
Boston, MA, May 20, 2013
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Outline
College of Engineering Tennessee State University

• Introduction
• Problem Statement
• Cooperative MIMO Network Model and Communication
  Schemes
• Cooperative MIMO Paradigm for Overlay Systems
• Cooperative MIMO Paradigm for Underlay Systems
• Numerical Analysis and Experiments
• Conclusions

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Introduction
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• MIMO Technology
• Multiple antennas transmit same data streams
  simultaneously it can be used to reduce energy,
  or extending communication range and error rate.
• Multiple antennas transmit different data streams
  simultaneously it can be used to provide higher
  data rate (multiplexing gain)

MIMO transceiver
Wireless MIMO network
However, it is unrealistic to equip multiple
antennas to small and inexpensive wireless
devices (e.g., wireless sensor nodes).
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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
Cooperative Communication MIMO Technology
Distributed individual single-antenna nodes
cooperating on information transmission and
reception as a multiple antenna array
MIMO links
Cooperative MIMO Schemes
Other hops
First hop
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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Cognitive radio A promising paradigm in wireless
  communication that enables efficient use of
  frequency resources
• Coexistence of licensed primary users (PUs) and
  unlicensed secondary users (SUs) in the same
  frequency band
• Cognitive capabilities
• Basic approaches (1) spectrum overlay, (2)
  underlay, and (3) interweave

Overlay
Underlay
Interweave
time
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Problem Statement
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Existing overlay schemes require the relay SUs to
  be in the convenient location, typically halfway
  between source and destination
• Existing underlay schemes cannot guarantee that
  the aggregated interference generated by SUs is
  maintained below the threshold

This Research Develop energy efficient
cooperative MIMO paradigms that can maximize the
diversity gain and significantly improve the
performance of both overlay and underlay systems.
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Network Model and Communication Schemes
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
Underlying network Network G (V,E) of
single-antenna radio nodes. d-Clustering the
distance between two nodes in a cluster d.
d-clusters are called Cooperative MIMO nodes, and
the nodes of G are called primary
nodes. D-Cooperative-MIMO links Let A and B be
two d-clusters, and A and B be the subsets of A
and B, respectively. Suppose there are mt nodes
in A and mr nodes in B. If the largest distance
between any node of A and any node of B is not
larger than D, a D-mtmr virtual MIMO
transmission link can be defined between A and
B. Heterogeneity The size and the diameter of a
cluster, and the length of virtual MIMO links can
be different.
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Cooperative MIMO Paradigm for Overlay System
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
SUs assistant PUs communication (SUs can use
the PUs channel when PUs communication
completed)

• Step 1 data transmission from the primary
  transmitter to m SUs via 1m SIMO link
• Step2 data transmission from m SUs to the
  primary receiver via a m1 MISO link

• Optimization (at SUs)
• Maximize the distance that the secondary users
  can be away from the primary users.
• Minimize the energy usage at the secondary users.
  

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Cooperative MIMO Paradigm for Underlay System
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
SUs utilize PUs channel obliviously SUs share
the PUs frequency resource without any knowledge
about the PUs signals and under the strict
constraint that the spectral density of their
transmitted signals fall below the noise floor at
the primary receivers

• Optimization at SUs
• Maximize the communication performance (minimize
  error rate)
• Minimize the energy usage at the secondary users.
  

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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
Numerical Analysis and Experiments

• Energy Model
• Energy consumption per bit at each primary node
  for local/intra data transmission
• Energy consumption per bit at each primary node
  for local/intra reception

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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Energy consumption per bit at each primary node
  for data transmission in long-haul mt mr
  cooperative MIMO link
• Energy consumption per bit at each primary node
  for data reception in long-haul mt mr
  cooperative MIMO link

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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Parameters

Pct 48.64 mw Pcr 62.5 mw
Psyn 50 mw Nf 10 dB
Ttr 5 µs s2 N0/2 -174 dBm/Hz
GtGr 5 dBi ? 0.1199
Gd G1dkMl (G1 10 mw, k 3.5, Ml 40 dB) Gd G1dkMl (G1 10 mw, k 3.5, Ml 40 dB)
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Numerical analysis in Overlay System
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Step 1 data transmission from the primary
  transmitter to m SUs via 1m SIMO link
• Step2 data transmission from m SUs to the
  primary receiver via a m1 MISO link

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Numerical Analysis in Underlay System
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Since only transmission energy brings
  interference from SUs to primary receiver, only
  the transmission energy is considered
• Intra/local transmission
• Long-haul transmission

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Numerical Analysis Results
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
In overlay systems the SUs can assist/relay the
PUs transmission even when SUs are far away from
primary transmitter (Pt) and primary receiver (Pr)
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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
In underlay systems the SUs are able to share the
PUs frequency resource without any knowledge
about the PUs signals and under the strict
constraint that the spectral density of their
transmitted signals fall below the noise floor at
the primary receivers.
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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• System Evaluation in Real Wireless Environment
• Build a cooperative cognitive testbed using the
  universal software radio peripheral (USRP)
  platform and GNU Radio
• Each node consists an USRP motherboard
  RFX2400 daughterboard
• signal processing module implemented in GNU Radio
  running in a general purpose computer under
  Ubuntu operating system
• BPSK modulation and demodulation is used for all
  experiments

Underlay System
Overlay System
Licensed Primary Transmitter
Licensed Primary Receiver
unlicensed Secondary Transmitter
unlicensed Secondary Receiver
unlicensed Secondary Users as Relay
unlicensed Secondary Cooperative Transmitter
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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Overlay System Underlay System
• (Bit error rate performance) (Packet
  error rate performance)
• Single-relay Cooperation
• Multiple-relay cooperation

Amplitude With Cooperation Without Cooperation
800 0 24.85
600 6.12 70.28
400 13.72 97.1
Average 6.61 64.08
Trial (Node distance 2 m) With Cooperation Without Cooperation
1 2.21 9.13
2 2.27 12.73
3 2.89 10.76
Average 2.46 10.87
Multiple Relays Coop. (Node Distance 30 ft) Single Relay Cooperation Without Cooperation
2.93 2.21 9.13
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Conclusions
College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks

• Proposes energy efficient cooperative MIMO
  paradigms for cognitive radio networks.
• In overlay systems, SUs can relay the primary
  transmissions even when they are far away from
  the primary users
• In underlay systems, SUs are able to share the
  primary users frequency resources without any
  knowledge about the PUs signals, even when they
  are close to the primary receivers
• Performance evaluation in real wireless
  environment verified the advantage of the
  proposed paradigms.

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College of Engineering Tennessee State University
Cooperative MIMO Paradigms for Cognitive Radio
Networks
Thank you! Questions?