在一個無線區域網路裡，每個節點在通信的時候，通信範圍內每個節點都聽的到。通信時的訊息封包包含了節點ID。透過三角定位，訊息強度，信號來源方位等方法，可以判斷出一個點的位置。如果對一個點進行長時間的追蹤，就可以蒐集到一些使用者資訊，侵犯到使用者的隱私。 一些論文透過暫停通訊後更新ID的方式來降低節點被追蹤的準確性，達到保護位置隱私的效果。由於每個節點對於隱私的要求不太一樣，因此一個機制最好是使用者導向的，可以自己決定更新ID的位置與時間。在考量到使用者導向，透過區域性同步和更新ID的方式，使得更新能夠達到最佳的位置隱私效果。 在設計新的機制時，會運用新方法達到更好的位置隱私效果，但有時這些方法也會透露出資訊給敵人利用，使得位置隱私的效能不增反減。我們提出ID追蹤法，針對使用交換ID的方法時，利用其一對一交換的關係，挑戰交換ID的位置隱私效能。我們另外提出一個新交換機制，透過多對多的交換，因此不受ID追蹤法的挑戰。效能評估的結果顯示，新的追蹤方法是可以有效追蹤節點的，而新機制的效能也有達到最佳的位置隱私效果。 When nodes communicate in a wireless local area network (WLAN), all nodes within transmission range hears the transmitting packet. Every packet contains the ID of the transmitting node, and through triangulation, received signal strength and other methods, the location of the node can be detected. Long term tracking of a node can gather user information, violating one’s privacy. Recent works suggests that by pausing transmission and updating ID, a node can lower the chance of being tracked and obtain one’s location privacy. It is also suggested that a location privacy protection mechanism should be user-centric, having nodes update independently, fulfilling the different needs of each node. Considering the need for user-centric, local synchronization and different ID updating methods are proposed to achieve optimum location privacy. When designing a new mechanism, new ways are proposed to achieve better location privacy, but at the same time, it can also reveal information to an adversary resulting less location privacy. We propose a tracking method called ID tracking that can be used when a node swaps its ID with another, which lowers location privacy of the node. We propose a new mechanism that has nodes switching their IDs and can counter the proposed tracking method. Simulation result shows the effectiveness of the proposed tracking method against nodes that swaps IDs. Results also show that nodes using the new mechanism have good location privacy.
