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I'm implementing the technique found in this paper: http://front.sjtu.edu.cn/~jinyh/gradCourse/Paper/Wireless/SpotFi%20Decimeter%20Level%20Localization%20Using%20WiFi.pdf

to perform localization.

I've implemented 95% of the technique, but this one short algorithm is giving me problems.

Algorithm pseudocode

The explanation in pseudocode is very simple but the results I'm obtaining are wildly different than reported in the paper, and I don't think this is just a case of misreporting results.

Notice that to minimize the function in step 1, rho will always go to 0! Which is clearly not right.

An example of this algorithm being applied in the paper is given here, with the first figure being the unwrapped phase prior to running Algorithm 1 and the second one being the resulting phase.

Algorithm 1 Output Example

I can share my code so far for Algorithm 1 but I really think that I'm just missing something pretty essential in the description....

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    $\begingroup$ It's not true that $\rho=0$ necessarily minimizes the expression. Take as a simple example the expression $(a+b\rho)^2$, which is minimized by $\rho=-a/b$. $\endgroup$
    – Matt L.
    Commented Mar 17, 2016 at 18:24

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I think it's just a simple line fitting, assume that phase = at + b then the phase without offset is phase_without_offset = phase - at. I used ployfit function in matlab to implement the algorithm.The following picture is my result. enter image description here

I guess you are a student from SJTU, the same school with me, i'm also implementing the spotfi, can you tell me your email or qq, i want to talk with you! my email is mrshao at sjtu.edu.cn(please replace at with @).

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  • $\begingroup$ Thanks for your response, I had actually forgotten about this question... I'm not a student at STJU, is everyone at your school implementing spotfi?? $\endgroup$
    – Ethan
    Commented Jun 16, 2016 at 5:23
  • $\begingroup$ sorry, i thought you are a student from SJTU according to the link of paper. you said you have implemented 95% of spotfi, can you share the music code with me ? i cannot implement it. Thank you very much! $\endgroup$
    – shao
    Commented Jun 20, 2016 at 7:39
  • $\begingroup$ You can find the entirety of my code at this link: github.com/egaebel/lgtm/tree/master/csi-code I do have a bug in my algorithm 1 currently which I should have fixed within the week. $\endgroup$
    – Ethan
    Commented Jun 24, 2016 at 18:46
  • $\begingroup$ hi, i haven't found your modification about the algorithm 1 in github, can you update it? Thank you! $\endgroup$
    – shao
    Commented Jul 15, 2016 at 2:01

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