在無線感知網路中，使用者必須和他鄰居在相同的頻道上會合後才能建立連線。一般而言，透過共通的頻道來做為訊息控制是最容易達成這種會合程序的方法。然而，當未授權的使用者(次級用戶SU或感知用戶CU)嘗試使用那些授權的頻帶時，必須避免對授權使用者(主要用戶PU)的干擾。因此使用特定的通用頻道即可能出現主要用戶長期佔據頻道的問題，並且在節點密度過高或傳輸量較大的環境下可能產生控制訊息的頻道不敷使用的問題。在理想的情況下，次級用戶應該嘗試透過所有的頻道來與他人會合以增加傳輸的可能性。因此跳頻(Channel hopping)這個方法就被用來解決單一控制頻道的問題。本文中，我們以參數系統(Quorum system)來建立跳頻協定並分析四個效能測量標準。分別為:1) 所需的最大會合時間、2) 頻道負載量、3) 會合的程度、及4) 找尋不受主要用戶干擾所需的最大會合時間。此外，我們也針對主要用戶的活動情形做進一步探討，當主要用戶長期佔據某些頻道時可以動態調整跳頻的頻道數量。相較於其它建立控制頻道的協定，我們的協定不僅是在設計一個跳頻系統，更考量到無線感知網路中主要用戶的影響。透過省略一些無法使用的頻道，可縮短次級用戶會合時間進而提升效率。

In cognitive radio networks (CRNs), users must rendezvous their neighbors in order to establish the communication between each other. Generally, using common control channel is the simplest way to establish rendezvous process. However, when unlicensed users, such as secondary users (cognitive users), try to access licensed spectrum, it should avoid interference with licensed users (primary users, PUs). A special common control channel may cause the PU long-time blocking problem, and in a high density environment of nodes or traffic may cause the control channel saturation problem. Ideally, SUs should try to rendezvous each other on all licensed channels to maximize the possibility of transmission. Channel hopping (CH) have been proposed to avoid the problems of a single control channel. In this thesis, we use quorum-based system to establish a novel CH protocols and analyzing its performance with the four metrics: 1) Maximum time to rendezvous, 2) Channel loading, 3) Degree of rendezvous, and 4) Maximum conditional time to rendezvous. Furthermore, we will dynamically change the number of hopping channels in different periods when PUs occupy some channels for a long time. By skipping some unavailable channels, the period of rendezvous for SUs can be decreased and the performance can be improved.

[1] Federal Communications Commission, “Spectrum policy task force report, FCC 02-155,” November 2002.
[2] Ian F. Akyildiz, Won-Yeol Lee and Kaushik R. Chowdhury, “CRAHNs: Cognitive Radio Ad Hoc Networks,” Ad Hoc Networks, Vol. 7, pp. 810-836, 2009.
[3] Paramvir Bahl, Ranveer Chandra and John Dunagan, “SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in IEEE 802.11 Ad Hoc Wireless Networks,” Proceedings of the ACM MobiCom, pp. 216-230, 2004.
[4] Kaigui Bian, Jung-Min Park, and Ruiliang Chen, “A Quorum-Based Framework for Establishing Control Channels in Dynamic Spectrum Access Networks,” Proceedings of the ACM MobiCom, pp. 216-230, 2009.
[5] Kaigui Bian, Jung-Min Park, and Ruiliang 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.
[6] Kaigui Bian, and Jung-Min Park, “Asynchronous Channel Hopping for Establishing Rendezvous in Cognitive Radio Networks,” Proceedings of IEEE Conference on Computer Communications (INFOCOM), pp. 236-240, 2011.
[7] Kaigui Bian, and Jung-Min Park, “Maximizing Rendezvous Diversity in Rendezvous Protocols for Decentralized Cognitive Radio Networks”, Proceedings of IEEE Transactions on Mobile Computing, Vol. PP, No. 99, pp. 1, 2012.
[8] Tao Chen, Honggang Zhang, G.M. Maggio, and I.Chlamtac, “CogMesh: A Cluster-based Cognitive Radio Networks,” Proceedings of IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), pp. 168-178, 2007.
[9] Tao Chen, Honggang Zhang, M. D. Katz and Zheng Zhou, “Swarm Intelligence Based Dynamic Control Channel Assignment in CogMesh,” Proceedings of IEEE International Conference on Communications (ICC) Workshops, pp. 123-128, 2008.
[10] K. R. Chowdhury, and I. F. Akyildiz, “OFDM-Based Common Control Channel Design for cognitive Radio Ad Hoc Networks,” Proceedings of IEEE Transactions on Mobile Computing, Vol.10, No. 2, pp. 228-238, 2010.
[11] C. Cordeiro, and K. Challapai, “C-MAC: A Cognitive MAC Protocol for Multi-Channel Wireless Networks,” Proceedings of IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), pp. 147-157, 2007.
[12] Luiz A. DaSilva and Igor Guerreiro. “Sequence-Based Rendezvous for Dynamic Spectrum Access,” Proceedings of IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN) pp. 1-7, 2008.
[13] Fen Hou, Lin x. Cai, Xuemin Shen, and Jianwei Huang, “Asynchronous Multichannel MAC Design with Difference-Set-Based Hopping Sequences,” Proceedings of IEEE Transactions on Vehicular Technology, Vol. 20, No. 4, pp. 1728-1739, 2011.
[14] 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.
[15] Zhiyong Lin, Hai Liu, Xiaowen Chu, and Yiu-Wing 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.
[16] Hai Liu, Zhiyong Lin, Xiaowen Chu, and Yiu-Wing Leung, “Jump-Stay Rendezvous Algorithm for Cognitive Radio Networks,” Proceedings of IEEE Transactions on Parallel and Distributed System, Vol. 99, No. PrePrints, 2012.
[17] B. F. Lo, I. F. Akyildiz and A.M. Al-Dhelaan, “Efficient Recovery Control Channel Design in Cognitive Radio Ad Hoc Networks,” Proceedings of IEEE Transactions on Vehicular Technology, Vol.59, No9, pp.4513-4526, 2010.
[18] Chao-Fong Shih, Tsung Ying Wu, and Wanjiun Liao, “DH-MAC: A Dynamic Channel Hopping MAC Protocol for Cognitive Radio Networks, ” Proceedings of IEEE International Conference on Communications (ICC), pp. 1-5, 2010.
[19] Mark D. Silvius, Feng Ge, Alex Young, Allen B. MacKenzie, and Charles W. Bostian, “Smart Radio: Spectrum Access for First Responders,” Proceedings of SPIE, Vol. 6980, 2008.
[20] D. Yang, J. Shin, and C. Kim, "Deterministic Rendezvous Scheme in Multichannel Access Networks," Proceedings of Electronics Letters, Vol. 46, No. 20, pp. 1402-1404, 2010.
[21] Yifan Zhang, Qun Li, Gexin Yu, and Baosheng 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.
[22] Jun Zhao, Haito Zheng, and Guang-Hua Yang, “Distributed Coordination in Dynamic Spectrum Allocation Networks,” Proceedings of IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN), pp. 259-268, 2005.