在現代社會，外出遊玩是人們生活中非常重要的部分，例如一群朋友出行，家庭度假，或者團體旅遊等。但在出遊的過程中，我們經常會碰到朋友走失的問題，這個時候要找到對方通常是让人很困扰的事情，需要打電話確認，找地標物等。另外一方面，隨著智慧型手機的快速發展，由於它的便利性和實用性，智慧型手機已經成為人們手中非常普遍的電子產品。而且一般的智慧型手机都有多种的定位方式，例如GPS和WiFi定位等。所以我們利用智慧型手機的這些特性來解決類似的走失的問題。

本篇論文，我們提出了一個基於Android的追蹤好友位置的架構。這個架構由一個location server，一個SMS receiver和多個locators構成。利用這個架構，在出行的時候我們可以追蹤不同用戶所在的位置，行動的軌跡，同時規劃出當前用戶到指定用戶的優化路徑等。除此之外,在網絡不穩定的情況下，locator也可以回傳自己的位置。我們希望通過這個系統可以解決人們在出遊的時候走散的問題,更加方便的知道好友的位置。

As we know that people like to do outdoor activities together such as travelling, shopping and so on. It is a very important part in our life. However, we may encounter such a problem that somebody wonder away from the group. At this moment, it can be a hassle for us to track his position quickly, sometimes you have to make a call to ensure it. Simultaneously, smart phones are getting more accessible to the common people for its affordable price and convenience. Most of the smart phones has some technologies to locate its location such as GPS and WiFi Positioning. So we want to find a simple method to solve this kind of problem.

In this thesis, we propose an architecture which consists of one server, one SMS receiver and many locators. We can track clients' locations with our system, and we may plan a simple path between two clients. Besides we add some features to make it complete. For example, we switch between GPS and Network Location to get an accurate location. In additions, we can get the locator’s location even if its internet is instable. We hope that our system can solve the problem that people may be missing when we are outside.

Table of Contents i
List of Figures iii
List of Tables iv
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Background 3
2.1 Android . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Location Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1 GPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.2 Cell Id Positioning . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.3 WiFi Positioning . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Google Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Signal Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Related Work 8
3.1 Glympse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Find my Friends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Jink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Design Architecture 13
4.1 Application of the Locator Side . . . . . . . . . . . . . . . . . . . . . 14
i
4.1.1 Location Approach . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1.2 Track the Friends’ Locations . . . . . . . . . . . . . . . . . . . 16
4.1.3 Path Planning . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1.4 The Track of the Locator . . . . . . . . . . . . . . . . . . . . 17
4.1.5 Show Info . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 SMS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3 The Location Server . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5 Implementation 18
5.1 Building Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1.1 The Structure of Android Application . . . . . . . . . . . . . 19
5.2 Positioning Event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2.1 Location Info . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2.2 Positioning Event in Locator . . . . . . . . . . . . . . . . . . 20
5.2.3 SMS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2.4 IsBetterLocation . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 The Track of Locator . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.4 Path Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5 Distance Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.6 Location Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.6.1 MySql Database . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.6.2 Tomcat Server . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6 Analysis 29
6.1 Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2 Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2.1 Experiment 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.2.2 Experiment 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.2.3 Experiment 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7 Conclusion 39
7.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

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[11] Signal strength. http://appleinsider.com/articles/10/07/15/inside_apples_changes_to_the_iphones_signal_strength_visual_bars.

[12] Communication quality. http://www.3cblog.idv.tw/2014/01/
see-the-actual-signal-strength-on-your-iphone-with-this-quick-tweak.html.

[13] Friend locator apps: Glympse vs. find my friends. http://www.pcadvisor.co.uk/review/android-tablet-apps/glympse-app-review-3505444/.

[14] How to share your location in real time on iphone or android. http://www.guidingtech.com/33190/share-location-real-time/.

[15] Glympse review: share your location with whom you want, when you want. http://www.pcadvisor.co.uk/review/android-tablet-apps/glympse-app-review-3505444/.

[16] Glympse. https://play.google.com/store/apps/details?id=com.glympse.android.glympse&hl=zh.

[17] Find my friends. https://www.apple.com/apps/find-my-friends/.

[18] Bump your stalking skills with custom geofences in apple’ s find my friends. http://arstechnica.com/apple/2013/03/
bump-your-stalking-skills-with-custom-geofences-in-apples-find-my-friends/.

[19] Jink. http://briian.com/22110/jink.html.

[20] Locate my friends. https://play.google.com/store/apps/details?id= com.fsp.android.friendlocator.

[21] Life360. https://play.google.com/store/apps/details?id=com.life360.android.safetymapd&hl=zh_TW.

[22] Maintaining a current best estimate.
http://developer.android.com/guide/topics/location/strategies.html#BestPerformance.