If you know the path loss model, you can calculate the distance based on the received power.

Dear Sattar

Thanks for your answer.

How can I determine the the path loss model? Is there any method for this?

The model of the channel radio is very complicated. In literature there are different statistics model based on different scenarios and on the bandwidth of the signal used by the system. Moreover there are a lot of methods for measuring the distance between two wireless nodes with a different precision and accuracy. One of these (the more simple but the most inaccurate) is read the RSSI received by the wireless node. Another methods is computing the time of flight of a signal transmitted by the one of the nodes.

Please find a clear explanation of the problem here

https://www.dsprelated.com/showarticle/1100.php

I hope that it is useful

Kind Regards

Giovanni

Dear Giovanni

Thanks for your answer. Since using path loss model is very complicated, RSSI is inaccurate and using time of flight needs time synchronization between nodes, which method you offer?

Thanks for your help.

What kind of network are you using? There is a group of communication networks with ranging capabilities on the market (eg UWB). There are some ZigBee devices with phase shift measurement methods used for ranging. You need to be more specific in your question...

Dear Imani,

the choose of the method for measuring the distance between two or more active nodes depends on the application and the system precision that your would achieve. UWB system exhibits the most accuracy and precision in the distance estimation but are more expensive than other solutions present in literature.

So could you specifice the application and/or the system precision desired?

Currently, I'm working on a ranging system that doesn't need a synchronization between the transmitter and a receiver. Essentially it will based on the measurement of the Differential time of Arrival (DToA). Maybe this could be a good solution even for your problem.

Regards

Dear Jacek and Dear Giovanni

We want use one of these methods in cognitive radio networks.

Dear Imani,

What is the precision that you would achieve in the distance measurements? If the system has to achieve a precision in order of few centimeters, probably a good solution is the timestamp method. It is clear explaned in the link on previous post. The method doesn't need a synchonization between the two active nodes but one of these has to be the reference of the system. However the precision is constrained to the frequency of the clock. A clock of 800Mhz corresponds to a maximum precision of 37 cm about.

I hope it is useful

Regards