The theory and practice of signal strength-based location estimation

Location estimation enables many innovative applications and is an exciting area of research. With the growing use of wireless technology in enterprise networks, it is an interesting technical challenge to develop techniques for indoor location estimation that leverage the deployed wireless infrastructure. Elegant, cost-effective techniques would present a compelling business proposition. In this paper, we summarize various approaches researchers have studied for the problem of indoor location estimation, concentrating on signal-strength based techniques directed towards 802.11 wireless networks. We also summarize an interesting insight into the best possible accuracy achievable by any technique due to limits imposed by the physical behavior of the radio signal. We identify that the issues driving research work in this area will not only be location accuracy, but other factors like deployment ease, management simplicity, adaptability, and cost of ownership and maintenance. We conclude with some open research problems in this area