本論文提出一項支援微小型感測平台漫遊(Roaming)於無線感測網路中的群體換手(Clustered Handoff)機制，名為EcoFlock。群體的概念意味著一群固定在相同物體上的感測器，擁有相似的環境背景，便可以視為同一群體，而且感測器支援群體特色並不會對自己本身造成過度的負擔。同一個群體中的感測器可以利用群體式換手機制而更快速的漫遊於整個網絡中，相較於基本的序列式換手機制(Serialized Handoff)，達到更好的效果。EcoPlex是一個讓簡單的感測平台能夠漫遊且無縫式參與多元特色、無線的點對點傳輸網路的一個基礎架構系統。EcoFlock延伸自EcoPlex並實作群體式換手機制的可行性。實驗結果顯示出，EcoFlock擁有快速的換手時間、很短的運算與傳輸時間，以及很高的資料傳輸率，並且在這些優點之下，並不會增加感測平台的複雜度。

EcoFlock is a clustered handoff control scheme for supporting roaming of ultra-compact sensor nodes
in wireless sensor networks (WSNs). Cluster features are intended for a group of nodes that may be
mounted on the same object without overburdening. Nodes in the same cluster can perform clustered
handoff to achieve faster roaming compared to the baseline of serialized handoff. We demonstrate the
feasibility of this idea by extending EcoPlex, an infrastructure system that enables simple wireless
platforms such as Eco nodes to roam and participate seamlessly in a feature-rich, wireless ad hoc
network. Experimental results show EcoFlock to be efficient for fast handoff time, low latency and
high data throughput with minimal node complexity.

[1] AKYILDIZ, I. F., XIE, J., AND MOHANTY, S. A survey of mobility management in nextgeneration all-ip-based wireless systems. Wireless Communications, IEEE 11, 4 (Aug. 2004),
16–28.
[2] ALLIANCE, Z. http://www.zigbee.org/.
[3] ATALAH, K., MAC`I AS, E., AND SU`AREZ, A. A proactive horizontal handover algorithm based
on rssi support by a new gradient predictor, July 2008.
[4] BELLAVISTA, P., CORRADI, A., AND GIANNELLI, C. Adaptive Buffering-Based on Handoff Prediction for Wireless Internet Continuous Services. 2005, pp. 1021–1032.
[5] CHEN, C.-J., AND CHOU, P. Ecodaq: A case study of a densely distributed real-time system for high data rate wireless data acquisition. In Embedded and Real-Time Computing Systems and Applications, 2008. RTCSA ’08 14th IEEE International Conference on (Aug 2008), pp. 427–
432.
[6] CHEN, M.-C., CHEN, J.-L., AND YAO, P.-C. Efficient handoff algorithm for bluetooth networks. vol. 4, pp. 3884–3889 Vol. 4.
[7] GEORGE, M. L., KALLIDUKIL, L. J., AND CHUNG, J.-M. Bluetooth handover control for roaming system applications. vol. 1, pp. I–404–7.
[8] GNAWALI, O., JANG, K.-Y., PAEK, J., VIEIRA, M., GOVINDAN, R., GREENSTEIN, B., JOKI, A., ESTRIN, D., AND KOHLER, E. The tenet architecture for tiered sensor networks. In SenSys’06: Proceedings of the 4th international conference on Embedded networked sensor systems(New York, NY, USA, 2006), ACM, pp. 153–166.
[9] GUO, C., GUO, Z., ZHANG, Q., AND ZHU, W. A seamless and proactive end-to-end mobility solution for roaming across heterogeneous wireless networks. Selected Areas in Communications,
IEEE Journal on 22, 5 (June 2004), 834–848.
[10] HALTEREN, A. V., BULTS, R., WAC, K., KONSTANTAS, D., WIDYA, I., DOKOVSKY, N., KOPRINKOV, G., JONES, V., AND HERZOG, R. Mobile patient monitoring: The mobihealth
system. The Journal on Information Technology in Healthcare 2, 5 (October 2004), 365–373.
[11] HEINZELMAN, W. R., CHANDRAKASAN, A., AND BALAKRISHNAN, H. Energy-efficient communication protocol for wireless microsensor networks. In System Sciences, 2000. Proceedings
of the 33rd Annual Hawaii International Conference on (Jan. 2000), pp. 10 pp. vol.2–.
[12] HUANG, C.-M., LIN, M.-S., AND WONG, H.-L. The handoff control scheme for computing powerless devices and its applications in the digital home network. Comput. Commun. 31, 14
(2008), 3275–3285.
[13] KANG, R.-J., CHANG, H.-P., AND CHANG, R.-C. A seamless vertical handoff scheme. pp. 64–71.
[14] KE, C.-Y., KO, N.-Y., HSUEH, C.-H., AND LEE, C.-H. Ecoplex: Empowering compact wireless sensor platforms via roaming and interoperability support.
[15] KIM, J.-M., PARK, S.-H., HAN, Y.-J., AND CHUNG, T.-M. Chef: Cluster head election mechanism using fuzzy logic in wireless sensor networks. In Advanced Communication Technology, 2008. ICACT 2008. 10th International Conference on (Feb. 2008), vol. 1, pp. 654–659.
[16] KONSTANTAS, D., JONES, V., AND HERZOG, R. Mobihealth - innovative 2.5 / 3g mobile services and applications for healthcare. In Proceedings of the Eleventh Information Society Technologies (IST) Mobile and Wireless Telecommunications (2002).
[17] LEE, T.-S., KE, C.-Y., KO, N.-Y., HSUEH, C.-H., CHEN, W.-H., LEE, C.-H., AND CHOU, P. H. EZ-Gate: Design and implementation of a high-performance, Linux gateway for ZigBee compliant sensor networks. Tech. rep., National Tsing Hua University, 2007.
[18] LI, J. H., LUO, S., DAS, S., MCAULEY, T., PATEL, M., STAIKOS, A., AND GERLA, M. An integrated framework for seamless soft handoff in ad hoc networks. pp. 1–7.
[19] LIU, G., AND MAGUIRE, G. A class of mobile motion prediction algorithms for wireless mobile computing and communications. Mobile Networks and Applications 1, 2 (1996), 113–121.
[20] NRF24LU1 PRODUCT BRIEF, N. http://www.nordicsemi.com/files/Prod_brief_RFSilicon_nRF24LU1.pdf.
[21] OLIVEIRA, L., RODRIGUES, A., GORGONIO, K., PERKUSICH, A., AND DA SILVA, L. D. Specification and analysis of a bluetooth handoff protocol for real-time applications. pp. 179–183.
[22] RAMJEE, R., LA PORTA, T. F., SALGARELLI, L., THUEL, S., VARADHAN, K., AND LI,L. Ip-based access network infrastructure for next-generation wireless data networks. Personal Communications, IEEE 7, 4 (Aug 2000), 34–41.
[23] SUN, J.-Z., AND SAUVOLA, J. Mobility and mobility management: a conceptual framework. pp. 205–210.
[24] TAHA, A.-E. M., HASSANEIN, H. S., AND MOUFTAH, H. T. A multi-class, sub-adaptation module for forced vertical handoffs. pp. 175–180.
[25] TOOLS, T. K. . D. http://www.keil.com/c51/.
[26] WANG, W., AND JANTSCH, A. An algorithm for electing cluster heads based on maximum residual energy. In IWCMC ’06: Proceedings of the 2006 international conference on Wireless communications and mobile computing (New York, NY, USA, 2006), ACM, pp. 1465–1470.
[27] WU, W., BANERJEE, N., BASU, K., AND DAS, S. K. SIP-based vertical handoff between wwans and wlans. vol. 3, pp. 66–72.
[28] YAAKOB, N. B., AND ANWAR, F. Seamless handover mobility schemes over high speed wireless environment. In Proceedings of the International Conference on Electrical Engineering and Informatics (June 2007).
[29] ZHANG, T., AGRAWAL, P., AND CHEN, J.-C. Ip-based base stations and soft handoff in all-ip wireless networks. Personal Communications, IEEE 8, 5 (Oct 2001), 24–30.