在本論文中，IEEE 802.11p WAVE (Wireless Access in Vehicular Environments) 通訊協定下更有效率的頻譜使用方法將會被探討。IEEE P1609家族的標準是一系列以IEEE 802.11p 為基礎的高階標準，其中定義了WAVE的架構以及多頻道作業方法在其定義的媒體擷取層(MAC)中之控制頻道(CCH)和服務頻道(SCH)。然而，依據目前的協定，同時只有一個頻道和一個通訊端點會被使用，其他的頻道和通訊端點都會被浪費。因此， Exploitable Node-Assisted WBSS (WAVE Basic Service Set) Broadcasting Mechanism便被提出來支配位未被使用的頻道與空閒的通訊端點。此方法可在不影響原有傳輸效能的條件下直接性的減少車輛進入RSU範圍時取得服務資訊的時間。除此之外，目前協定中固定的Sync Interval值以及不可變動比例的CCH Interval和SCH Interval設計雖然可以確保車輛進入RSU範圍時取得服務資訊的時間，但同時也會造成效能上的低落與頻譜的浪費。因此，Dynamic Sync Interval Scheme 以及Dynamic Ratio of CCH Interval and SCH Interval Scheme便被提出來改進現有的頻道使用狀況。

In this thesis, the effective channel usage is investigated in IEEE 802.11p WAVE (Wireless Access in Vehicular Environments) communication protocol. IEEE P1609 family is a set of higher layer standards based on IEEE 802.11p, and WAVE architecture and multi-channel operations over CCH (Control Channel) and SCH (Service Channel) are defined in the MAC layer. However, only one channel and one node will be used at a time to transmit data and the others will be wasted. Thus, an Exploitable Node-Assisted WBSS (WAVE Basic Service Set) Broadcasting Mechanism is proposed to utilize empty channels and idle nodes. The proposed mechanism can reduce the delay time for getting service information when vehicles are traveling into the broadcasting coverage of RSU. In addition, the Sync Interval is fixed and the ratio of CCH interval and SCH interval is also invariable in the original scheme for guaranteeing OBU to get WBSS in specific period. But, these features may cause bandwidth wastage. Therefore, a Dynamic Sync Interval Scheme and a Dynamic Ratio of CCH Interval and SCH Interval Scheme are proposed to improve the channel usage.

[1] “Standard Specification for Telecommunications and Information Exchange Between Roadside and Vehicle Systems - 5 GHz Band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” ASTM DSR STD E2313-02, 2002.
[2] I. T. S. Committee, “IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Multi-channel Operation (1609.4),” November 2006.
[3] I. T. S. Committee, “IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Resource Manager (1609.1),” October 2006.
[4] I. T. S. Committee, “IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Security Services for Applications and Management Messages (1609.2),” July 2006.
[5] I. T. S. Committee, “IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE) - Networking Service (1609.3),” April 2007.
[6] M. S.M. S. Gong,M.X., “A combined proactive routing andmulti-channelMAC protocol for wireless ad hoc networks,” Proceedings of Conference on Broadband Networks, 2005 2nd International. Volume 1, Page(s): 444 - 453, October 2005.
[7] I. W. Group, “IEEE P802.11p/D3.0, Draft Amendment for Wireless Access in Vehicular Environments (WAVE),” July 2007. 339, March 2007.
[9] J. W. Hoi-Sheung Wilson So, “McMAC: A Multi-Channel MAC Proposal for Ad-Hoc Wireless Networks,” Technical Report, April 2005.
[10] D. T. Jan Blumenthal, Frank Reichenbach, “Minimal Transmission Power vs. Signal Strength as Distance Estimation for Localization in Wireless Sensor Networks,” Proceedings of 3rd Annual IEEE Communications Society on Sensor and Ad Hoc Communications and Networks. Page(s): 761-766, September 2006.
[11] C.-A. Y. Jenhui Chen, Shiann-Tsong Sheu, “A new multichannel access protocol for IEEE 802.11 ad hoc wireless LANs,” Proceedings of 14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications. Volume 3, Page(s): 2291 - 2296, September 2003.
[12] J.W. JeonghoonMo, Hoi-SheungWilson So, “Comparison of multi-channelMAC protocols,” Proceedings of the 8th ACM international symposium on Modeling, analysis and simulation of wireless and mobile systems. Page(s): 209 - 218, October 2005.
[13] N. H. V. Jungmin So, “Multi-channel mac for ad hoc networks: handling multi-channel hidden terminals using a single transceiver,” Proceedings of the 5th ACM international symposium on Mobile ad hoc networking and computing. Page(s): 222 - 233, May 2004.
[14] P. Z. Y. X. Mingfei Wang, Linlin Ci, “Multi-Channel MAC Protocols in Wireless Ad Hoc and Sensor Networks,” Proceedings of International Colloquium on Computing, Communication, Control, and Management. Volume 2, Page(s): 562 - 566, August 2008.
[15] J. D. Paramvir Bahl, Ranveer Chandra, “SSCH: slotted seeded channel hopping for capacity improvement in IEEE 802.11 ad-hoc wireless networks,” Proceedings of the 10th annual international conference on Mobile computing and networking. Page(s): 216 - 230, September 2004.
[16] K.-C. L. T.-W. H. C.-C. L. C.-L. C. Shie-Yuan Wang, Hsi-Lu Chao, “Evaluating and improving the TCP/UDP performances of IEEE 802.11(p)/1609 networks,” Proceedings of IEEE Symposium on Computers and Communications. Page(s): 163 - 168, July 2008.
[17] C.-Y. L. J.-P. S. Shih-Lin Wu, Yu-Chee Tseng, “A Multi-channel MAC Protocol with Power Control for Multi-hop Mobile Ad Hoc Networks,” Proceedings of International Conference on Distributed Computing Systems. Volume 45, Number 1, Page(s): 101- 110, April 2001.
[18] Y.-C. T. J.-L. S. Shih-Lin Wu, Chih-Yu Lin, “A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks,” Proceedings of International Symposium on Parallel Architectures, Algorithms and Networks. Page(s): 232 - 237, December 2000.
[19] I. C. Society, “IEEE Standard for Information technology- Telecommunications and information exchange between systems- Local and metropolitan area networks- Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” June 2007.
[20] G.-L.-A. J. Tzamaloukas, A., “Channel-hopping multiple access,” Proceedings of IEEE International Conference on Communications. Volume 1, Page(s): 415 - 419, June 2000.
[21] A. L.-G. Wing-Chung Hung, K.L.Eddie Law, “A Dynamic Multi-Channel MAC for Ad-Hoc LAN,” Proceedings of 21st Biennial Symposium on Communications. Page(s): 31 - 35, April 2002.