Indoor positioning

There are two recent survey papers on indoor positioning.

Survey of Wireless Indoor Positioning Techniques and Systems
Hui Liu; Darabi, H.; Banerjee, P.; Jing Liu;
Systems, Man, and Cybernetics, Part C: Applications and Reviews, IEEE
Transactions on
Volume 37, Issue 6, Nov. 2007 Page(s):1067 - 1080

A survey of indoor positioning systems for wireless personal networks
Yanying Gu; Lo, A.; Niemegeers, I.;
Communications Surveys & Tutorials, IEEE
Volume 11, Issue 1, First Quarter 2009 Page(s):13 - 32