適地性服務是一種以使用者地理位置資訊為基礎的附加網路服務。隨著可攜式行動裝置的顯著發展，愈來愈多適地性服務應用程式被開發在智慧型手機或是平板電腦上。由於行動裝置的服務時間受限於電池的電量，本篇論文的動機為如何在行動裝置上使用行人導覽服務時達到減少耗電量以延長裝置服務時間。在同時考量定位精確度及鄰近興趣點(Point of Interests，PoI)下，我們提出以行動裝置內建感測器輔助定位以動態調整GPS取樣頻率(sampling rate)並維持定位準確度之行人導覽服務省電機制(a power efficient touring scheme, PETS)。同時，我們提出的機制(PETS)根據使用者目前的位置與鄰近興趣點的關係，判斷哪些興趣點的內容應該優先下載儲存，以避免不必要的資料傳輸造成的耗電量。此外，考量到資料傳輸所造成的耗電量，當鄰近的WiFi無線網路基地台能提供足夠好的頻寬時，我們提出的機制(PETS)利用WiFi取代3G/3.5G/4G行動網路。根據實驗結果，我們提出的機制(PETS)能節省約38%的耗電量。

Location-based service (LBS) is a general class of add-on network services using the information on the geographical positions of users. With the significant growth of portable and mobile devices, integrating LBS into new smart devices, i.e., smart phone or tablet PC, becomes the main trend of the next-generation consumer electronic services. Due to limited power lifetime, this thesis concentrates on the power saving issue of a pedestrian touring service using smart mobile devices. Regarding the positioning accuracy and neighboring points of interests (POIs), a power efficient touring scheme (PETS) is proposed to dynamically adjust the GPS sampling rate with the help of embedded sensors in smart mobile devices to keep enough positioning accuracy and low power consumption. At the same time, the proposed PETS prioritizes which POIs should be pre-downloaded and cached based on the relationship between the current geo-location of a pedestrian and neighboring POIs for reducing unnecessary transmission power. Regarding the power efficiency of transmission, the PETS utilizes Wi-Fi network instead of 3G/3.5G/4G network once the neighboring Wi-Fi access points are able to provide good enough bandwidth. Based on our performance results, the PETS can save about 38% power consumption.

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