Abstract: This paper focuses on how to position the mobile device indoor by using signal strength in 802.11-based system. It introduces a 802.11-based positioning system called the maximal cluster centered positioning algorithm (MCCPA). The MCCP system locates mobile objects via collecting the sensed power strengths of the mobile objects to multiple wireless access points. Based on realizing MCCPA, the paper gives a new algorithm named MMCCPA to correct the positioning results by using the history record information of mobile devices. The main idea of MMCCPA is that it also considers the probability of users’ appearance in the specific area in order to correct results, as an adjustment to the environment factors, so as to increase the preciseness and decrease the count quantity. The experimental results show that the location information provided by MMCCPA assures higher correctness than MCCPA.

Key words: Wireless networks, Signal strength, Positioning algorithm, 802.11, History record

摘要： 研究了在基于802.11的系统中，如何通过信号强度进行移动设备的室内定位。在研究并实现最大群中心定位算法MCCPA的基础之上，给出了一种利用移动终端的历史位置信息对定位结果进行修正的室内定位算法(MMCCPA)。其主要思想是，在给定前一时间使用者所在位置的条件下，将使用者出现在特定范围的概率列入考量加以修正，并作为对环境因素影响的调整，这样不仅减少计算量，而且明显提高了位置估算的正确率。

关键词: 无线网络, 信号强度, 定位算法, 802.11, 历史记录