在建立以IEEE 802.15.4標準為底層通訊協定且具有自我調整架構特性之無線個人區域網路時，網路中所有的節點須具備自動建立並維護其連結性的能力，因此節點的同步是一項相當重要的機制。

IEEE 802.15.4標準為一項針對短距離、低傳輸速率的無線個人區域網路所設計的通訊協定，其提供beacon的使用以使網路具有同步、QoS及低功耗等優點，目前IEEE 802.15.4標準對於beacon的使用規範仍有不明確的地方，因此拓樸較為複雜的網路將存在beacon conflict的問題，這會使網路中的節點失去同步而無法傳輸，因此建立一個避免衝撞的beacon使用方式，實為一重要的課題。

在此論文中，我們選擇Motorola Lab所提出的Beacon_Tx_Offset方
式作為beacon conflict的解決方案，並參考TDMA頻道存取的方式來規劃Beacon_Tx_Offset的使用，透過上述兩種方式的結合以避免相鄰節點間發生beacon conflict而造成後續無法傳輸資料。

While establishing the wireless personal area network that bases on IEEE 802.15.4 LR-WPANs communication protocol and with the self-configurable characteristic, every node in the network must be able to automatically establish and maintain its link capacity. Therefore, the synchronization between nodes is an important mechanism.

IEEE 802.15.4 LR-WPANs specification is the communication protocol designed for a wireless personal area network with short-range and low data rate RF transmissions, it support the operation of beacon to provide some advantages, like network synchronization, QoS and low power consumption. At present, there is still ambiguous in IEEE 802.15.4 LR-WPANs specification for the beacon operating. Therefore, there will be a beacon conflict problem in the complex topology network, it will cause nodes to lose the synchronization with its parent node and be unable to transmit. So, the establishment of a method to avoid beacon conflict is an important issue. 

In this paper, we select the Beacon_Tx_Offset method purposed by Motorola Lab as the beacon conflict solution and refer TDMA channel access method to schedule the use of Beacon_Tx_Offset. Through the two method described above, we could avoid the beacon conflict between neighbor nodes and following incapacity of data transmission.

目錄
第一章 緒論......................................1
1-1研究動機與目的................................1
1-2研究內容......................................4
1-3論文組織架構..................................6
第二章 IEEE 802.15.4 通訊協定之介紹..............7
2-1 IEEE 802.15.4 通訊協定簡介...................7
2-2節點種類......................................9
2-3網路拓樸.....................................10
2-4操作模式.....................................12
2-5 The Superframe Structure....................13
2-6 Beacon Conflict Problem	.....................15
2-6-1 Direct Beacon Conflict....................16
2-6-2 Indirect Beacon Conflict..................17
第三章 相關研究.................................19
3-1 Direct Beacon Conflict Solution.............19
3-2 Indirect Beacon Conflict Solution...........23
第四章 系統設計與實做...........................24
4-1 Beacon Conflict Solution....................24
4-2 Beacon_Tx_Offset Scheduling.................25
4-3測試環境與流程...............................30
4-3-1 測試平台..................................30
4-3-2 測試環境..................................32
4-4 測試結果....................................34
第五章 未來發展與結論...........................40
參考文獻........................................42
英文附錄........................................43

圖目錄
圖2-1-1   IEEE 802.15.4無線個人網路通訊協定架構..7
圖2-3-1   星狀拓樸與點對點式拓樸................10
圖2-3-2   叢集樹拓樸............................11
圖2-4-1   IEEE 802.15.4媒體存取控制層操作模式...12
圖2-5-1   Superframe Structure..................13
圖2-6-1   The cluster-tree topology model.......15
圖2-6-1-1 Direct Beacon Conflict範例1...........16
圖2-6-1-2 Direct Beacon Conflict範例2...........17
圖2-6-2-1 Indirect Beacon Conflict範例..........18
圖3-1-1   Beacon-Only Period範例................20
圖3-1-2   Beacon_Tx_Offset範例..................21
圖4-1-1   Beacon_Tx_Offset示意圖................24
圖4-2-1   TDMA Example..........................26
圖4-2-2   基本Beacon_Tx_Offset Scheduling.......26
圖4-2-3   Beacon_Tx_Offset Scheduling...........28
圖4-2-4   Beacon_Tx_Offset Scheduling範例.......29
圖4-3-1-1 MC13213內部功能及SPI連結圖............30
圖4-3-1-2 測試平台： MC13213 硬體開發版.........31
圖4-3-2-1 IEEE 802.15.4及IEEE 802.11通訊頻道....33
圖4-3-2-2 BO及SO設定及Time Slot Length..........33
圖4-4-1   BO = 5，SO = 1設定下的Beacon接收......34
圖4-4-2   BO = 6，SO = 2設定下的Beacon接收......35
圖4-4-3   BO = 7，SO = 3設定下的Beacon接收......35
圖4-4-4   BO = 8，SO = 4設定下的Beacon接收......36
圖4-4-5   BO = 9，SO = 5設定下的Beacon接收......36
圖4-4-6   BO = 10，SO = 6設定下的Beacon接收.....37
圖4-4-7   BO = 11，SO = 7設定下的Beacon接收.....37
圖4-4-8   BO = 12，SO = 8設定下的Beacon接收.....38
圖4-4-9   BO = 13，SO = 9設定下的Beacon接收.....38
圖4-4-10  BO = 14，SO = 10設定下的Beacon接收....39

公式目錄
公式2.1	.......................................14
公式2.2	.......................................14
公式4.1	.......................................24
公式4.2	.......................................24
公式4.3	.......................................27
公式4.4	.......................................27
公式4.5	.......................................27

[1].IEEE 802.15.4 WPAN™ Task Group 4 (TG4), http://www.ieee802.org/15/pub/TG4.html
[2].IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks Specific requirements Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low – Rate Wireless Personal Area Networks (LR - WPANS) IEEE 802.15. 4™- 2003, October 2003.
[3].IEEE 802.15.4 WPAN™ Task Group 4b (TG4b), http://www.ieee802.org/15/pub/TG4b.html.
[4].Monique Bourgeois Brown, “Beacon scheduling   mechanism”, September 2004.
[5].Freescale™ Semiconductor, http://www.freescale.com/
[6].Huai-Rong Shao, Jinyun Zhang and Hui Dai, “Enhancements to IEEE 802.15.4”, July 2004.
[7].Myung Lee, Jianliang Zheng, Yong Lin, Huai-Rong Shao, Hui Dai and Jinyun Zhang, Hoin Jeon, “Combined proposal of Enhancements to IEEE 802.15.4”, September 2004.
[8].MC13213: 2.4 GHz RF transceiver and 8 – bit MCU with 60k of Flash for Zigbee application, http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC13213&nodeId=01J4Fs25657103.
[9].MC13211/212/214 Zigbee™ - Compliant Platform 2.4 GHz Low Power Transceiver for the IEEE 802.15.4 Standard plus Microcontroller Reference Manual, October 2006.
[10].Sinem Coleri Ergen, Pravin Varaiya, “TDMA Scheduling Algorithm for Sensor Networks”, July 2005.