Presentation on theme: "Secrecy Capacity Scaling of Large-Scale Cognitive Networks Yitao Chen 1, Jinbei Zhang 1, Xinbing Wang 1, Xiaohua Tian 1, Weijie Wu 1, Fan Fu 2, Chee Wei."— Presentation transcript:
Secrecy Capacity Scaling of Large-Scale Cognitive Networks Yitao Chen 1, Jinbei Zhang 1, Xinbing Wang 1, Xiaohua Tian 1, Weijie Wu 1, Fan Fu 2, Chee Wei Tan 3 1 Dept. of Electronic Engineering, Shanghai Jiao Tong University 2 Dept. of Computer Science and Engineering, Shanghai Jiao Tong University 3 Dept. of Computer Science, City University of Hong Kong
2 Outline Introduction Network Model and Definition Independent Eavesdroppers Colluding Eavesdroppers Conclusion
Motivations Security is a major concern in wireless networks 3 Mobile Payment Virtual Property Privacy Military Communication
4 Motivations Physical Layer Security Assume eavesdroppers have infinite computation power Require the intended receiver should have a stronger channel than eavesdroppers Provable security capacity Cryptographic methods Key distribution Rapid growth of computation power Improvement on decoding technology
5 Related works Secrecy capacity in large-scale networks Guard zone  Artificial noise + Fading gain (CSI needed)  Using artificial noise generated by receivers to suppress eavesdroppers’ channel quality   O. Koyluoglu, E. Koksal, E. Gammel, “On Secrecy Capacity Scaling in Wireless Networks”, IEEE Trans. Inform. Theory, May  S. Vasudevan, D. Goeckel and D. Towsley, “Security-capacity Trade-off in Large Wireless Networks using Keyless Secrecy,” in Proc. ACM MobiHoc, Chicago, Illinois, USA, Sept  J. Zhang, L. Fu, X. Wang, “Asymptotic analysis on secrecy capacity in large-scale wireless networks,” in IEEE/ACM Trans. Netw., Feb Cited from 
6 Motivations Limited spectrum resources and CR networks Key questions: What is the impact of security in cognitive networks? What is the performance we can achieve?
7 Outline Introduction Network Model and Definition Independent Eavesdroppers Colluding Eavesdroppers Conclusion
8 Network Model and Definition – I/III Cited from   J. I. Choiy, M. Jainy, K. Srinivasany, P. Levis and S. Katti, “Achieving Single Channel, Full Duplex Wireless Communication”, in ACM Mobicom’10, Chicago, USA, Sept
9 Network Model and Definition – II/III Random permutation traffic, no cross network traffic Communication Model Physical Model: Primary user i transmits to primary user j Define the physical model for secondary users and eavesdroppers similarly. Interference from other primary TXs Interference from other primary RXs Interference from secondary TXs
10 Network Model and Definition – III/III Definition of Per Hop Secrecy Throughput: Independent eavesdropper Colluding eavesdroppers Definition of Asymptotic Capacity Similarly, we can define the asymptotic per-node capacity for the secondary network
11 Outline Introduction Network Model and Definition Independent Eavesdroppers Colluding Eavesdroppers Conclusion
12 Independent Eavesdroppers Successful transmission No eavesdropper can decode the message
13 Independent Eavesdroppers
14 Independent Eavesdroppers
15 Independent Eavesdroppers Scheduling scheme Cell Partition Round-Robin Scheduling: Tessellate the network into cells. Different cells take turn to transmit. Secondary users can transmit in non-occupied cells with the guarantee of affecting primary transmissions little. Figure: Simple 9-TDMA
16 Independent Eavesdroppers No order cost comparing to the scenario without security concern!
17 Outline Introduction Network Model and Definition Independent Eavesdroppers Colluding Eavesdroppers Difference with previous case Conclusion
SINR of Colluding Eavesdroppers – maximum ratio combining of SINR Bound the SINR of eavesdroppers: Disjoint rings with same size. Eavesdroppers in the same ring has a similar SINR. Artificial noise + Path loss gain + Cooperation 18 Colluding Eavesdroppers
20 Colluding Eavesdroppers Result comparison Cooperation in cognitive networks helps to increase secrecy capacity, compared to stand-alone networks .  J. Zhang, L. Fu, X. Wang, “Asymptotic analysis on secrecy capacity in large-scale wireless networks,” to appear in IEEE/ACM Trans. Netw., 2013.
21 Outline Introduction Network Model and Definition Independent Eavesdroppers’ Case Colluding Eavesdroppers’ Case Conclusion
22 Conclusion In this paper, we study physical layer security in cognitive networks. Our scheme adopting self-interference cancellation is very efficient. Cooperation between secondary network and primary network in CR networks can help to strengthen physical layer security.