Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic • Hacker News Board

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#21

Post by PaulHoule » Fri, Aug 05, 2022, 7:55 PM UTC

toast0 wrote: post #20

PaulHoule wrote: post #17

What's going to matter for audio streaming in an automotive (the case they are concerned about) is the energy consumption in the receiver, not the transmitter. They are measuring the second.

Who cares about power usage of the receiver in a car? It's got access to the 12v alternator/battery and as long as it turns off properly hen the car is off, radio power is going to be negligible compared to moving the vehicle, nevermind things like air conditioning, power steering, headlights, etc. Otoh, the transmitter in your pocket might not be plugged in, so that's important.

Actually I got it backwards.

Believe it or not I don't have a smartphone and find my life is perfectly meaningful w/o it (e.g. there is nothing convenient about using cellular streaming in my car if I have to drive a few miles from home for it to work.) so I was thinking about streaming from the car audio system to headphones and not the other way around.

But generally it is the smaller, more mobile device which is going to have battery problems, which is going to be the phone if you are streaming from a phone to your car.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#22

Post by ellisd » Fri, Aug 05, 2022, 8:01 PM UTC

qbasic_forever wrote: post #16

ellisd wrote: post #13

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data s…

Where are you planning to use this, is it for a stage or concert? A lot of folks have found in those environments 2.4 ghz wireless (like bluetooth) is flakey and unreliable from all the interference of the audience's devices. I've read folks prefer stuff like 900mhz where almost no one has stuff using it in the area. Akiba and Freaklabs has done some great write-ups about his stage show work that are worth exploring:…

Off stage, within the 2.4 ghz ocean: the audience. Your point is well taken that spectrum saturation will be an issue. Low range/power consumption, not centralization are the driving factors in the design. Thanks for the share!

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#23

Post by bhaney » Fri, Aug 05, 2022, 8:03 PM UTC

> The experiments showed that when using BR/EDR’s 2 Mb/s, the practical throughput were on average 0.786 Mb/s. [...] Meanwhile, when using BLE’s 1M PHY, the average throughput were around 0.522 Mb/s and 0.938 Mb/s when using 2M PHY. The bit rate speed for the BR/EDR 1Mb/s mode were at an average of 0.104 Mb/s. Using these results, it shows that on average, the BR/EDR throughput speeds are faster than the BLE throughput speeds.

I'm probably misunderstanding what the author intended here, but this just seems wrong. 0.104Mb/s (BR/EDR 1 Mb/s mode) is not faster than 0.522Mb/s (BLE 1M mode), nor is 0.786Mb/s (BR/EDR 2 Mb/s mode) faster than 0.938Mb/s (BLE 2M mode). I can't see how you would reach the conclusion that BR/EDR is faster "on average" than BLE with those results unless you're also factoring in BR/EDR's 3 Mb/s mode in some way, even though there is no BLE equivalent to compare it to.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#24

Post by jsjohnst » Fri, Aug 05, 2022, 8:05 PM UTC

ellisd wrote: post #13

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data s…

Why use Bluetooth at all? Depending on the details, hiding a wire inside a sleeve should be doable. If you really want wireless, I’d suggest considering something like RFM69 / RFM95 type radios. You can easily find a wide variety of form factors, optionally with integrated Arduino compatible MCU, from Adafruit.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#25

Post by ellisd » Fri, Aug 05, 2022, 8:08 PM UTC

com2kid wrote: post #15

ellisd wrote: post #13

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data s…

> You could simply pick the strongest signal and be reasonable assured that it's your personally worn wrist device. > Am I missing something? Phone is in your pocket, wrist worn device is on other side of your body. Another device with unobstructed line of sight across the room may have a stronger signal strength.

I'm actively trying to avoid a phone, rather a dedicated LED controller likely containing an AVR or ESP32. A simple button based paring process to associate the wrist band with its personal controller is likely necessary to solve the RSSI issue you point out.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#26

Post by arcticbull » Fri, Aug 05, 2022, 8:17 PM UTC

ChrisMarshallNY wrote: post #18

The "LE" is more about behavior , rather than some power-saving tech. It affords low-energy-use behavior. Short bursts, ad hoc connections, small amounts of data, etc. If we make it behave like Classic, it will suck energy like Classic. I like using BLE, more than Classic (BR/EDR). It's a bit pedantic, getting things set up, but that can be abstracted, fairly easily[0]. If we program for iOS/WatchOS/TVOS/iPadOS, we'l…

This is exactly right from my experience in having worked on a few different BLE devices, one of which you've almost certainly used.

If you use it like classic bluetooth, you're going to have a bad time like classic bluetooth. Information in advertising packets (which can be as infrequent as a few seconds) is also used extensively in sensor applications which can last a few years on a coin cell battery.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#27

Post by mafuyu » Fri, Aug 05, 2022, 8:23 PM UTC

arcticbull wrote: post #26

ChrisMarshallNY wrote: post #18

The "LE" is more about behavior , rather than some power-saving tech. It affords low-energy-use behavior. Short bursts, ad hoc connections, small amounts of data, etc. If we make it behave like Classic, it will suck energy like Classic. I like using BLE, more than Classic (BR/EDR). It's a bit pedantic, getting things set up, but that can be abstracted, fairly easily[0]. If we program for iOS/WatchOS/TVOS/iPadOS, we'l…

This is exactly right from my experience in having worked on a few different BLE devices, one of which you've almost certainly used. If you use it like classic bluetooth, you're going to have a bad time like classic bluetooth. Information in advertising packets (which can be as infrequent as a few seconds) is also used extensively in sensor applications which can last a few years on a coin cell battery.

If you live in the middle ground where you want to maintain connectivity, but sporadically send chunks of data on the order of a few to 100s of k, that's where it gets a bit tricky. BLE is still much better for power than classic in those scenarios, but the protocol isn't really intended for that type of bandwidth, and you might end up with a lot of custom stuff on top.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#28

Post by ellisd » Fri, Aug 05, 2022, 8:30 PM UTC

jsjohnst wrote: post #24

ellisd wrote: post #13

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data s…

Why use Bluetooth at all? Depending on the details, hiding a wire inside a sleeve should be doable. If you really want wireless, I’d suggest considering something like RFM69 / RFM95 type radios. You can easily find a wide variety of form factors, optionally with integrated Arduino compatible MCU, from Adafruit.

It's a really good point, a wire based sensor eliminates a dead battery and interference as failure points. The Wireless accelerometer feature should come after the basic animation concepts have been ironed out and tested. I really appreciate the reference to RMF* type radios - I had not come across them in my reading.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#29

Post by kwyjibo123456 » Fri, Aug 05, 2022, 8:52 PM UTC

When I was a PhD student, we did similar measurements for LTE and WiFi for multipath TCP. These are non-trivial measurements due to lots of overlaying effects and I honestly speaking do not trust a BSc student to get this right.

Besides that I think the measurement scenario is unfair, as BTLE was designed for a different use case, i.e., always on and always able to overhear beacons. Comparing BT and BTLE for data transmission only is like measuring a race between a horse and a fish in the open sea.

Re: Analysis of energy consumption of Bluetooth Low Energy versus Bluetooth Classic

#30

Post by aaaaaaaaaaab » Fri, Aug 05, 2022, 9:08 PM UTC

ellisd wrote: post #13

On this topic: I'm very interested in streaming accelerometer data in real time from a wrist worn device to a body mounted LED controller. My goal is to modify the LEDs animations based on the hand position. Given the sensor bitrate and low latency required for this data, it would appears that BT Classic may be better solution than BLE. Beyond the power consumption needs, BLE connectionless broadcasting of the data s…

Just use a wire?