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. I

Answer 1

I'm just adding this in case someone finds it useful, it's a post I wrote describing my experience working with Bluetooth technologies in mobile:

https://medium.com/@agustin.aliaga/lessons-learned-from-building-a-mobile-app-with-bluetooth-low-energy-support-29615b399630

Answer 2

Recently two different Bluetooth technology available :

- Classic Bluetooth - Range : 30 foot or 10 meter

- Bluetooth Low Energy or Bluetooth Smart - 200 ft and beyond

• Consumes only a fraction of the power of Classic Bluetooth radios.

• Powered by small, coin-cell batteries.

• Can operate these devices for more than a year without recharging.

• Enhanced range : optimize range to 200 feet and beyond.

• Ultra-low peak, average and idle mode power consumption.

• Lower implementation costs.

• Multi-vendor interoperability.

• Data Transfers : 8 octet minimum up to 27 octets of packet maximum.

• Speed : 1 Mbps.

• Advanced sniff-sub rating to achieve ultra low duty cycles.

• Range : 100 meters ( Increased modulation index ). Range may vary depending on class of radio used in an implementation:

Class 3 radios – have a range of up to 1 meter or 3 feet

Class 2 radios – most commonly found in mobile devices – have a range of 10 meters or 33 feet

Class 1 radios – used primarily in industrial use cases – have a range of 100 meters or 300 feet

• Robustness : 24 bit CRC ( maximum robustness against interference ) Strong Security : Full AES-128 encryption using CCM - Counter Mode Cipher (encryption and authentication)

This information is from : http://www.bluetooth.com/Pages/Bluetooth-Smart.aspx

For more information regarding classic Bluetooth or BLE you can check above link.

Answer 3

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.

Answer 4

Your question:

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

is going to be platform specific. In Android I am sure that you can arrange to keep BLE scanning going on in the background, although that may be a battery concern.

On iOS the background application rules are more restrictive. I do not believe you will be able to continue scanning in the background at all.