Indoor localization techniques and applications are getting attention in the area of smart homes. This paper focuses on radio frequency identification (RFID)-based localization, because RFID technology has been widely deployed owing to its cost-effectiveness and energy efficiency. This paper consists of two parts: existing localization techniques and challenges in localization. Existing localization techniques are compared in terms of accuracy, methods, and advantages/disadvantages.

The paper classifies existing localizations into three classes: triangulations, scene analysis (also known as fingerprint), and proximity detection based on cell of origin. Since different techniques have different accuracy, performance, and device requirements, applications and target location characteristics should be considered when selecting the appropriate technique.

The paper includes many pointers to related work. The presented RFID localization techniques will be helpful in introducing this area to interested beginners. However, both the existing techniques and challenges are very roughly described in poor English. Readers who are interested in the challenges should look to the referenced papers for detailed descriptions.