Android Bluetooth VS Bluetooth Low Energy

Question

I am trying to create an application that needs to exchange small size of data - just to notify that the devices are close enough - for as long as the smart phone is running. It is my understanding that the traditional bluetooth consumes significant amount of battery so that having it turned on for hours is not viable. I am looking at BLE but still concerned with the battery capacity.

Q0 Is it possible to have BLE turned on as long as the phone is running?

Q1 Is there a difference between the two technologies with respect to signal distance? and how far can they travel?

Q2 Is there any limitation on number of devices that can be connected simultaneously?

Q3 Does battery consumption varies depending on the size of data exchanging?

Q4 If the devices have to be connected and disconnected number of times, would the phone be able to tell the time difference between the connection?

Answer 1

I will try to answer what ever I found when working on the same. Some of the devices in the market do not support BLE, though there is software support the hardware will not be enabled or present.

Is it possible to have BLE turned on as long as the phone is running?

Yes, you can. There are 2 modes for BLE one scanning and other is advertising. Usually the devices having only BLE will do advertising.

Is there a difference between the two technologies with respect to signal distance? and how far can they travel?

Yes, there are differences with respect to speed, data packet size, range and battery consumption.. The range of BLE (upto 250m approx) is less than compared to classic BT (upto 700-800m approx). The data transfer rate is also very low . it can transfer upto max of 27 octet in a single packet with an average speed of ~100kbps, where as classic EDR has speed of 2mbps streaming Bluetooth low energy connections will lose a great deal of the huge potential power savings

Is there any limitation on number of devices that can be connected simultaneously?

The BLE works on master and slave. Number of slaves can be connected to master.

Does battery consumption varies depending on the size of data exchanging?

As per my power measurement conducted EDR is better than BLE for long run, where there is data transfer in regular intervals when devices are awake and ideal.

If the devices have to be connected and disconnected number of times, would the phone be able to tell the time difference between the connection?

Yes. If in this case if there is connection to transfer and then disconnect. It is better to keep EDR for long run, rather than LE connect and disconnect.

The above answers are based on experiments conducted while choosing BT technology for wearable device, the results might differ.