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Does using wireless MCU is better or using a stand alone MCU connected with BLE module is better in terms of power transmitted by the Bluetooth?

Second question is there a way to make rssi value transmitted by the smartphone to the mcu via Bluetooth more stable to calculate the position of the person more accurately?

Third question is the rssi fingerprinting method is more accurate than rssi trilateration or not and is there any other techniques rather than those?

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1) The answer depends on what specific wireless enabled MCU you are using and what standalone MCU and standalone wireless module you are comparing it to. In general, I would expect an integrated module to be more efficient as there is more opportunity for optimisation. I am not familiar with BLE so I can't comment on it specifically or on modules in the market today.

2) RSS is sensitive to noise and interference (exactly how sensitive will be depend on the exact PHY implementation of BLE you are using) so what happens in the environment will cause fluctuations in the RSS value. This is especially true with PHY layers like BLE which use the popular 2.4GHz.

If you want to perform RSS localisation you have to accept that there will be errors introduced by these fluctuations and also possibly by the inaccuracy in estimation of the RSS. Instead of basing a localisation estimate on a single RSS value you might want to consider taking several measurements and then filtering them (perhaps by using the Kalman filter) before making localisation decisions. There are many RSS localisation schemes that you can look at and decide which will work for you.

I don't know the exact algorithms you are comparing but in general RSS fingerprinting based methods will be more accurate than just doing blind triangulation but then again fingerprinting is much more restrictive as the fingerprints have to collected and stored or delivered to the device. In addition devices relying on RSS fingerprinting will be limited to operating in a set area.

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  • \$\begingroup\$ Can i measure rssi value in bluetooth beacon directly ?? \$\endgroup\$ – Ahmed Essam Oct 3 '17 at 17:44
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It is hard to say anything in terms of transmitter power because, it depends on which MCU or BLE module you use. However, i prefer wireless MCU because they can provide you more space on board.

Again, it depends on how much accuracy you need and working environment. BLE operates on 2.4 GHz and this frequency band is widely used that will cause so much interference and noise. I did real time tracking for indoor environment by using trilateration method with BLE in my university time and i got 3 meter accuracy and this accuracy varies so much due to distance to the beacon source.

To make more accurate system, you should collect hundreds of BLE beacon packets to make location estimation based on RSSI information.

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