ABSTRACT
This chapter proposes crowd sensing solutions for locating the lost child, using low-power and miniature wearable devices without high cost cellular and global positioning system (GPS) modules. To solve the coverage and localization problems of wearable devices, focus on the investigation of nearby "crowds" of smartphones for transparent ranging and locating via peer collaboration. The chapter also proposes system architecture for smartphone-based transparent crowd localization with high-energy efficiency and location resolution; it develops a portable and low-cost wearable tag based on Bluetooth Low Energy (BLE) that could be embedded in kids' clothing or shoes with long operating time. The chapter also proposes semidefinite relaxation for location optimization under various unreliable sources in crowd sensing, which could overcome the over-fitting problem and large errors, and ensure best-effort solutions. The powerful computing/communication capacities of nearby smartphones, huge population in crowds, and the inherent mobility makes mobile crowd sensing (MCS) a fast-growing consumer-centric sensing paradigm.
