雙模式TDMA排程機制之智慧型無線監控平臺研製

Abstract

本論文建立一智慧型無線監控平臺系統，透過IEEE 802.15.4協定來實現無線感測網路(WSN)技術，並以德州儀器生產、擁有內嵌Transceiver的CC2530控制器做為系統核心晶片，搭配晶片內建的計時器作為TDMA時間分割基底，針對協定中的CSMA-CA機制進行修改來實現自行排程之TDMA(Time division multiple access)機制。為了達成無線感測網路中取樣時間點的精準及降低訊號還原失真的誤差，本論文中提出自行定義的同步訊框及定期的廣播，提供網路內感測節點的時間基準，在各自的規畫時槽內進行資料上傳和外接SD卡兩種不同存取上的切換設計。其中，SD卡適時的加入能提供當取樣資料之變異量不大時資料的直接存入，且感測節點端只需針對採樣資料區塊中部分進行上傳，如此程序運作降低一般感測節點端冗餘的資料處理與無線傳輸所造成電池能量加速耗竭的情況，並提升整體系統使用之時效性。在最終相關實驗結果中，證實同步訊框機制和時槽排程機制搭配的使用，能有效達成網路節點同步和免於資料傳輸的碰撞，亦驗證藉由雙模式自動切換機制和適當的資料存取，確實能完整呈現出整體網路對於感測訊號之還原能力。

A wireless intelligent surveillance platform which materializes wireless sensor network technique via the IEEE 802.15.4 communication protocol has been investigated in this study. The core chip of designed system is named for CC2530 controller which has embedded Transceiver and is produced by Texas Instruments. In order to achieve self-scheduling of TDMA mechanism, the segmentation basal of TDMA time will be based on built-in timer, and amend the CSMA mechanism in the protocol. While the number of variance of sampling data is small, by using SD card, data could be saved directly and only fractions of them are desired to be uploaded by sensor nodes, which improves the rapid depletion of batteries because of redundant data processing and wireless transmission in traditional sensor nodes, and then prolong life cycle of the proposed system. Moreover, in order to reach optimum sampling time on wireless sensor network as well as reduce distortion when signal recover; therefore, this study proposed self-defined synchronization frame and regular broadcast not only provide time base of the sensor nodes within the network, also allows data access to upload or saving in external SD card in planning time slot, respectively. In the end, according to the experimental results the synchronization mechanism along with the timeslot scheduling mechanism could not only effectively synchronize network nodes but avoid collision of data transmission; moreover, being able to restore sensing data in the whole network by taking advantages of dual-mode switching method and proper data access is verified as well.