Cooperative MIMO Paradigms for Cognitive Radio Networks

1. Dr. Liang Hong LHONG@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

2. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 Cooperative MIMO Paradigms for Cognitive Radio Networks College of Engineering Tennessee State University Outline • 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

3. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 diversity gain multiplexing gain College of Engineering Tennessee State University Introduction 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).

4. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 MIMO Link MISO Link SIMO Link SISO Link 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

5. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigms for Cognitive Radio Networks Primary Users PR PT Cognitive radioApromising 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 Secondary Users Primary users PT PR ST SR Overlay Underlay Interweave Secondary users an mt×mr cooperative MIMO link A cooperative MISO link A cooperative SIMO link time

6. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Problem Statement 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.

7. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 3×2 MIMO link College of Engineering Tennessee State University Network Model and Communication Schemes 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-mt×mr 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.

8. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigm for Overlay System 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 1×m SIMO link • Step2: data transmission from m SUs to the primary receiver via a m×1 MISO link Primary users PT PR Secondary users A cooperative MISO link A cooperative SIMO 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.

9. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigm for Underlay System Cooperative MIMO Paradigms for Cognitive Radio Networks Primary Users PR PT 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 Secondary Users SR ST mt×mr cooperative MIMO link • Optimization at SUs • Maximize the communication performance (minimize error rate) • Minimize the energy usage at the secondary users.

10. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 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

11. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 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

12. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigms for Cognitive Radio Networks • Parameters

13. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Numerical analysis in Overlay System Cooperative MIMO Paradigms for Cognitive Radio Networks Primary Users PR PT • Step 1: data transmission from the primary transmitter to m SUs via 1×m SIMO link • Step2: data transmission from m SUs to the primary receiver via a m×1 MISO link Secondary Users SR ST mt×mr cooperative MIMO link

14. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Numerical Analysis in Underlay System Cooperative MIMO Paradigms for Cognitive Radio Networks Primary Users PR PT Since only transmission energy brings interference from SUs to primary receiver, only the transmission energy is considered • Intra/local transmission • Long-haul transmission Secondary Users SR ST mt×mr cooperative MIMO link

15. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Numerical Analysis Results 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)

16. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 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.

17. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 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

18. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigms for Cognitive Radio Networks Overlay SystemUnderlay System (Bit error rate performance) (Packet error rate performance) • Single-relay Cooperation • Multiple-relay cooperation

19. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Conclusions 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.

20. Dr. Liang Hong LHONG@TNstate.edu (615) 963-5364 College of Engineering Tennessee State University Cooperative MIMO Paradigms for Cognitive Radio Networks Thank you! Questions?