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Suzan Bayhan* and Jussi Kangasharju

Extending Cognitive Radios with New Perspectives Delay Tolerant Networks and Social Network Analysis. Suzan Bayhan* and Jussi Kangasharju Department of Computer Science, University of Helsinki, Finland *bayhan@hiit.fi. ICUFN 2014, July 8- July 11, Shanghai, China.

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Suzan Bayhan* and Jussi Kangasharju

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  1. Extending Cognitive Radios with New PerspectivesDelay Tolerant Networks and Social Network Analysis Suzan Bayhan* and JussiKangasharju Department of Computer Science, University of Helsinki, Finland *bayhan@hiit.fi ICUFN 2014, July 8- July 11, Shanghai, China

  2. CR Vision in 1999 and in 2014 • In 1999, PhD thesis by Joseph Mitola III, KTH • A cognitive radio: • understands self, • understands the user’s goals, • understands networks, and • understands radio. • In 2014, • Infrastructure-based and centralizedarchitectureslimiting us • Mobilitylargelyoverlooked • Contextis missing(actors and theirinteractions) ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  3. Outline • An Overview of New Perspectives • Delay Tolerant Networks • An example scenario • Social Network Analysis • An example scenario • Conclusions ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  4. An Overview of New Perspectives Social Network Analysis (SNA) Social Awareness DelayTolerantNetworks (DTNs) Robustness to challenging environments Social-aware operation Grasp the information in the network Improved spectrum capacity ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  5. Delay Tolerant Networks (DTNs)store-carry-forward • No dependency on infrastructure • Like ad hoc networks, but no tight requirement on end-to-end paths/delay • Opportunistic, aka proximity-based communications • Traffic offloading • Censorship/monitoring-free! No one is in communication range of the other, how to communicate? Exploit MOBILITY of nodes ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  6. Opportunities of Opportunistic Communicationsfor CRNs DTN also known as opportunistic communications • DTN opportunism: if nodes happen to be at the transmission range of each other at a time (time and space) • DTN intermittently connected due to low node density, node mobility, etc. • Mobility as enabler • Robust to connection breakdowns • CRN opportunism: if frequency is idle (time, space, frequency dimensions) • CRN intermittently connected due to disruptions from PUs • Mobility as a curse • Robust to lack of assigned spectrum Can CR learn from DTNs how to tackle the intermittent connections? Retain key strengths of each paradigm ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  7. An Example Scenario: Contact Capacity w/wo CR-opportunism • Contact capacity:Amount of data that can be transmitted at a contact • Contact duration • Wireless channel capacity (bandwidth) ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  8. Three Scenarios • Scenario I: DTN: DTN contact capacity (only ISM band) • Scenario II: REM: REM-enabled contact capacity (ISM + m PU bands) • Retrieve the list of best channels from REM • Sense m channels • Aggregate idle PU channels + ISM Spectrum Radio Environment Map (REM) Channel availability at each location • Scenario III: RAND: Random selection contact capacity (ISM + 1 PU band) • Coordinate via ISM and tune to one PU channel • Sense it • Transmit via idle PU channel + ISM ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  9. A Closer Look • Contact duration T, ISM Channel capacity: B bps • N PU channels (fi , pi, mean availability p), capacity: βB • Spectrum sensing overhead: αT Channel capacity Transmission time Contact starts Contact ends t=0 t=T DTN transmission REM information, spectrum sensing Contact ends Contact starts REM (m sensing) RAND Sensing and transmission Coordinate to switch to the same channel Contact ends Contact starts ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  10. Contact Capacity δ: coordination overhead α: sensing overhead β : PU channel capacity/ISM capacity p: Mean PU channel availability m: # of channels sensed pj: availability of channel fj ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  11. Contact Capacity GainEffect of Sensing Overhead RAND, p=0.8 m=1, N=4, δ=0.01 RAND, p=0.5 Contact capacity gain = C(*)/Cdtn • If sensing is not cumbersome, contact capacity increases with CR-type opportunism. • Capacity: • REM > RAND > DTN ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  12. Effect of Sequential Sensing (m) 300% 200% 170% 30% Maximum m is bounded by min(T/α, N) Highest gain m* based on p and α ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  13. Summary • J. Huang et al. Mobility-Assisted Routing in Intermittently Connected Mobile CRNs, IEEE TPDS, 2014. • Jing Zhao, G. Cao, Spectrum-Aware Data Replication in Intermittently Connected CRNs, INFOCOM 2014. ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  14. Social Network AnalysisandSocial-awareness “Understand the self, Understand the network” Social network analysis (SNA) or network science tools: extract information hidden in the system either about individual nodes or the network as a whole. ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  15. Two Layered View of the Network (SCL) (WCL) ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  16. An Example Scenario: Social-aware Cooperative Sensing • Assume • a mesh CRN in WCL • An Erdös-Renyi CRN in SCL • A CRi assesses its neighbors according to: • Probability of sensing: is altruism realistic? (SCL) • Social distance: length of shortest path bw. two nodes (SCL) SCL WCL • Probability of sensing accurately (WCL) ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  17. An Example Scenario: Social-aware Cooperative Sensing (2) Social distance • F-sense: only friendship is considered (αf = 1) • S-sense: only sensing accuracy (αs = 1) • FSW-sense: All considered equally(αf = αs = αw= 1/3) Who are the best cooperators? Probability of sensing accurately Probability of Sensing (willingness) Should I sense for this CR? • A CR asked for cooperation senses probabilistically depending on the social distance (wj,i , ni,j-1) ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  18. Performance Evaluation pj,I: U(0.7,1) • Rejection ratio and social-distance between the cooperators can be decreased by using the social connectivity information. • Lowest social distance (# hops bw. two nodes) • More trusted cooperation • Lowest reject ratio • Lower waste of energy Similar sensing performance ICUFN 2014, Session 8A Cognitive Radio. July 10, 2014, Shanghai, China

  19. Conclusions • Cognitive radios can be empowered using the well-established knowledge in DTNs and SNA. • DTNs can improve by applying CR-type opportunism. • Social-connectivity layer hosts variety of information, so exploit it! Occupy the spectrum and let the CRs be move and be social!Thank you. Suzan Bayhan bayhan@hiit.fihttp://www.hiit.fi/u/bayhan ICUFN 2014, Session 9A Cognitive Radio. July 10, 2014, Shanghai, China

  20. References • C Güven, S Bayhan, F Alagöz, Effect of Social Relations on Cooperative Sensing in Cognitive Radio Networks, BlackSeaCom, 2013. • J. Huang et al. Mobility-Assisted Routing in Intermittently Connected Mobile Cognitive Radio Networks, IEEE Transactions on Parallel and Distributed Systems, 2013. • Zhu, Ying, et al. "A survey of social-based routing in delay tolerant networks: positive and negative social effects." IEEE Communications Surveys & Tutorials, 15.1 (2013): 387-401. • Kas, Miray, et al. "What if wireless routers were social? approaching wireless mesh networks from a social networks perspective." IEEE Wireless Communications, 19.6 (2012): 36-43. ICUFN 2014, Session 9A Cognitive Radio. July 10, 2014, Shanghai, China

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