[论文解读] Indoor Positioning with Radio Location Fingerprinting

Mikkel Baun Kjærgaard|arXiv (Cornell University)|Apr 27, 2010

Indoor and Outdoor Localization Technologies参考文献 78被引用 12

一句话总结

该论文提出 ComPoScan 系统，通过基于运动检测自适应切换低影响监控模式与主动扫描，缓解无线通信与定位之间的干扰。通过利用运动感知降低扫描频率，ComPoScan 将通信吞吐量提升 122 倍，延迟降低十倍，包丢失率减少 73%，同时在无需硬件修改的情况下保持高定位精度。

ABSTRACT

An increasingly important requirement for many novel applications is sensing the positions of people, equipment, etc. GPS technology has proven itself as a successfull technology for positioning in outdoor environments but indoor no technology has yet gained a similar wide-scale adoption. A promising indoor positioning technique is radio-based location fingerprinting, having the major advantage of exploiting already existing radio infrastructures, like IEEE 802.11, which avoids extra deployment costs and effort. The research goal of this thesis is to address the limitations of current indoor location fingerprinting systems. In particular the aim is to advance location fingerprinting techniques for the challenges of handling heterogeneous clients, scalability to many clients, and interference between communication and positioning. The wireless clients used for location fingerprinting are heterogeneous even when only considering clients for the same technology. Heterogeneity is a challenge for location fingerprinting because it severely decreases the precision of location fingerprinting. To support many clients location fingerprinting has to address how to scale estimate calculation, measurement distribution, and distribution of position estimates. This is a challenge because of the number of calculations involved and the frequency of measurements and position updates. Positioning using location fingerprinting requires the measurement of, for instance, signal strength for nearby base stations. However, many wireless communication technologies block communication while collecting such measurements. This interference is a challenge because it is not desirable that positioning disables communication. An additional goal is to improve the conceptual foundation of location fingerprinting. A better foundation will aid researchers to better survey and design location fingerprinting systems.

研究动机与目标

• 解决基于 Wi-Fi 的室内定位系统中主动扫描造成的干扰，避免影响并发通信。
• 提升大规模部署中多种异构客户端下指纹定位的可扩展性与效率。
• 最小化因扫描频率降低导致的测量不频繁所引起的定位精度下降。
• 利用现有 802.11 基础设施实现实时定位，无需硬件修改或额外传感器。
• 开发一种实用且可部署的系统，在真实环境中平衡通信性能与定位精度。

提出的方法

• 使用加速度计实现运动检测系统，以判断用户是否处于静止或移动状态。
• 根据运动状态动态切换监控模式（低影响）与主动扫描（高精度）以进行信号强度测量。
• 仅在检测到运动时启用自适应扫描，从而在空闲期间降低扫描频率。
• 利用兼容的网卡（如 Intel Centrino、Atheros）的监控模式，捕获信号强度数据而不干扰通信。
• 设计轻量级、实时的系统，将运动感知与定位更新逻辑集成，以最小化资源消耗。
• 通过仿真与真实环境部署双重方式评估系统，以验证在真实网络条件下性能与精度的可靠性。

实验结果

研究问题

• RQ1 如何在不损害定位精度的前提下，最小化 Wi-Fi 通信与定位扫描之间的干扰？
• RQ2 能否有效利用运动检测来降低主动扫描频率，从而提升通信性能？
• RQ3 基于用户运动的自适应扫描在真实部署中，对吞吐量、延迟和包丢失率的改善程度如何？
• RQ4 在显著降低扫描开销的同时，系统能否维持高定位精度？
• RQ5 该系统是否可在无需硬件修改的现有消费级设备上部署？

主要发现

• 与持续主动扫描相比，ComPoScan 将网络吞吐量提升了 122 倍。
• 系统将平均网络延迟降低了十倍，显著提升了实时通信性能。
• 在真实部署中，包丢失率降低了 73%，表明定位更新期间的可靠性得到提升。
• 仿真结果证实，运动检测系统与环境、网卡、信号强度模型及 AP 配置无关。
• 即使扫描频率降低，定位精度仍得以保持，因为系统仅在检测到运动时才激活完整扫描。
• 该系统与现有 802.11 硬件兼容，无需额外传感器或固件修改，可广泛部署于消费级设备。