Feasibility of a Wi-Fi Positioning System
I don't think that arduino is the right hardware for such a project. Better use a cheap android phone, there you have a stronger processor with more memory as well as a lot of sensors like compass, accelerometer, gyroscope and maybe in newer ones barometer, which you will need - also you have wifi. An arduino uno just comes without wifi and all the sensors. Also I guess a lot of persons already have a phone, so this will lower your project costs, because hardware is already available at most users. Last but not least I think you could use mobile phone vibrations to give feedback to the sight disabled users, oder sound commands like "go left" etc.