在無線感知網路(CRNs)中，主要用戶(PUs)擁有使用頻譜的絕對優先權。而為了有效率地利用頻譜，次級用戶(SUs)可透過跳頻(Channel hopping)技術，動態地使用主要用戶未使用的頻道進行通訊。
現存的跳頻技術大都著重於頻道對稱模型(Symmetric model)。在此模型下，所有次級用戶的可用頻道皆相同。然而，在實體的無線感知網路環境中，所有次級用戶可用頻道不盡相同的非對稱模型(Asymmetric model)是較為實際的。在本篇論文中，我們提出一套通用的跳頻演算法，在非對稱模型中，不僅能夠以短於其他方法的週期保證頻道的會合，也不需要對次級用戶的可用頻道進行任何限制。而根據我們進行的模擬結果，此演算法擁有優於其他方法的最大條件會合時間(MCTTR)，意即在次級用戶之可用頻道不盡相同的情況下，能夠以最短的時間保證會合的出現。

In cognitive radio networks (CRNs), primary users (PUs) have the absolute priority to access the license channels. To efficiently utilize the spectrum, secondary users (SUs) can dynamically access the unused channels by channel hopping (CH) schemes.
Most existing CH schemes focus on the symmetric model that assumes all SUs have the same available channel set. However, the asymmetric model, where SUs may have different available channels sets, is more critical in the real CRN environment. In this thesis, we propose a universal channel hopping algorithm called Triple-Double Matrix (TDM) that can guarantee rendezvous within shorter period than the previous works under the asymmetric model without any constraints on the available channels of each SU. According to our simulation results, TDM has better maximum conditional time-to-rendezvous (MCTTR) than previous works.

[1] A. Ghasemi, E.S. Sousa, “Spectrum Sensing in Cognitive Radio Networks: Requirements, Challenges and Design Trade-offs,” IEEE Communication Magazine, Vol. 46, pp. 32-39, 2008.
[2] I. Akyildiz, W. Lee, M. Vuran and S. Mohanty, “NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey,” Computer Networks, Vol. 50, No. 13, pp. 2127-2159, 2006.
[3] I. Akyildiz, W. Lee and K. Chowdhury, “CRAHNs: Cognitive Radio Ad Hoc Networks,” Ad Hoc Networks, Vol. 7, pp. 810-836, 2009.
[4] C. Cordeiro, K. Challapali, D. Birru, and N. Sai Shankar, “IEEE 802.22: The First Worldwide Wireless Standard based on Cognitive Radios,” IEEE Int’l Symp. on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), pp. 328–337, 2005.
[5] S. Krishnamurthy, M. Thoppian, S. Venkatesan, and R. Prakash, “Control Channel Based MAC-Layer Configuration, Routing and Situation Awareness for Cognitive Radio Networks,” IEEE Military Communications Conference (MILCOM), pp. 455–460, 2005.
[6] L. Le and E. Hossain, “OSA-MAC: A MAC Protocol for Opportunistic Spectrum Access in Cognitive Radio Networks,” Proceedings of the IEEE Wireless Communications & Networking Conference (WCNC), pp. 1426-1430, 2008.
[7] J. Pérez-Romero, O. Salient, R. Agustí, and L. Giupponi, “A Novel On-Demand Cognitive Pilot Channel enabling Dynamic Spectrum Allocation,” IEEE Int’l Symp. on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), pp. 46–54, 2007.
[8] Juncheng Jia, Qian Zhang, and Xuemin Shen, “HC-MAC: A Hardware-Constrained Cognitive MAC for Efficient Spectrum Management,” IEEE Journal on Selected Areas in Communications, Vol. 26, No. 1, pp. 106-117, 2008.
[9] C.-F. Shih, T. Y. Wu, and W. Liao, “DH-MAC: A Dynamic Channel Hopping MAC Protocol for Cognitive Radio Networks,” Proceedings of the IEEE International Conference on Communications (ICC), pp. 1-5, 2010.
[10] A. Sampath, D. Hui, Z. Haitao, and B.Y. Zhao, “Multi-channel Jamming Attacks using Cognitive Radios,” Proceedings of International Conference on Communications and Networks (ICCCN), 2007.
[11] Z. Lin, H. Liu, X. Chu, and Y.-W. Leung, “Jump-Stay Based Channel-hopping Algorithm with Guaranteed Rendezvous for Cognitive Radio Networks,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 2444-2452, 2011.
[12] K. Bian and J.-M. Park, “Maximizing Rendezvous Diversity in Rendezvous Protocols for Decentralized Cognitive Radio Networks,” IEEE Transactions on Mobile Computing, Vol. 12, No. 7, July 2013.
[13] K. Bian, J.-M. Park, and R. Chen, “Control Channel Establishment in Cognitive Radio Networks using Channel Hopping,” IEEE Journal on Selected Areas in Communications, Vol. 29, No. 4, pp. 689-703, 2011.
[14] P. Bahl, R. Chandra and J. Dunagan, “SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in IEEE 802.11 Ad Hoc Wireless Networks,” Proceedings of the Annual International Conference on Mobile Computing and Networking (MobiCom), pp. 216-230, 2004.
[15] K. Bian, and J.-M. Park, “Asynchronous Channel Hopping for Establishing Rendezvous in Cognitive Radio Networks,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 236-240, 2011.
[16] Y. Zhang, Q. Li, G. Yu, and B. Wang, “ETCH: Efficient Channel Hopping for Communication Rendezvous in Dynamic Spectrum Access Networks,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 2471-2479, 2011.
[17] H. Liu, Z. Lin, X. Chu, and Y.-W. Leung, “Jump-Stay Rendezvous Algorithm for Cognitive Radio Networks,” IEEE Transactions on Parallel and Distributed Systems, Vol. 23, No. 10, Oct. 2012.
[18] D. Yang, J. Shin and C. Kim, “Deterministic rendezvous scheme in multichannel access networks,” IEEE Electronics Letters Vol. 46 No. 20, Sept. 2010.
[19] G.-Y. Chang and J.-F. Huang, “A Fast Rendezvous Channel-Hopping Algorithm for Cognitive Radio Networks,” IEEE Communications Letters, Vol. 17, No. 7, July 2013.
[20] Z. Lin, H. Liu, X. Chu, and Y.-W. Leung, “Enhanced Jump-Stay Rendezvous Algorithm for Cognitive Radio Networks,” IEEE Communications Letters, Vol. 17, No. 9, Sept. 2013.
[21] V. A. Reguera, E. O. Guerra, R. D. Souza, E. M. G. Fernandez, and G. Brante, “Short Channel Hopping Sequence Approach to Rendezvous for Cognitive Networks,” IEEE Communications Letters, Vol. 18, No. 2, Feb. 2014.
[22] J. Shin, D. Yang, and C. Kim, “A Channel Rendezvous Scheme for Cognitive Radio Networks,” IEEE Communications Letters, Vol. 14, No. 10, Oct. 2010.
[23] I. Chuang, H.-Y. Wu, K.-R. Lee, and Y.-H. Kuo, “Alternate Hop-and-Wait Channel Rendezvous Method for Cognitive Radio Networks,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 746-754, 2013.
[24] I. Chuang, H.-Y. Wu, K.-R. Lee, and Y.-H. Kuo, “A Fast Blind Rendezvous Method by Alternate Hop-and-Wait Channel Hopping in Cognitive Radio Networks,” IEEE Transactions on Mobile Computing, Vol. PP, No. 99, Jan. 2014.
[25] S.H. Wu, C.C. Wu, W.K. Hon, and K.G. Shin, “Rendezvous for Heterogeneous Spectrum-Agile Devices,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 2247-2255, 2014.