how can I improve throughput for ble link?

[Ben.Qin]

I found many relative topics about improving throughput for ble link on this website. And this one How do I calculate throughput for a BLE link? told me how can I calculate the throughput. I thought "n" is beyond my control. It should be decided by protocol stack, right? This discussion dealing large data packet's through ble gave me an example and told me many details. I did in another similar way. I didn't use heart rate service but Nordic UART service, and I confirmed configurations, such as vlen = 1, max_len = 20, hvx_paprams.type = BLE_GATT_HVX_NOTIFICATION and so on, are the same as I was told. My peripheral is base on nrf51822 and s110_nrf51822_6.0.0_softdevice, while the central is Nexus 7 with android 4.4.4. I got just about 16Kbps throughput. But it's said that it should be more. Whatever connection parameters I set, it didn't seem helpful. What did I do in a wrong way?

[Asbjørn]

The throughput is dependent on the connection parameters as you say, but these can only be requested from the peripheral and will be set by the central.

How do you measure the throughput? Have you used a sniffer to check the amount of packages being sent across air? Have you had a look at this example?

[Ben.Qin]

There is a demo app on android catching the data from peripheral. Each data packet contains a sequence number. The received data sequenced without any missing. About 100 packets were received per second. So I thought the speed is about 16Kbps. Of cause I had read the example @Asbjørn pointed out. I hadn't found any distinguish difference. From the sniffer data, it owns a double speed to my nus project's. Should the service kinds make it different?

[Asbjørn]

I'm a bit confused, do you see twice the amount of data going through with the example I linked to compared to the UART example that you had been playing with?

The type of service shouldn't matter as long as you achieve the same connection parameters and setup. By double speed, you mean double the amount of packages going through?

[Ben.Qin]

@Asbjørn, thank you for your answers. I'll upload the data caught by sniffer, expecting it brings something useful. I don't know whether the app on android slows down the speed. Can the sniffer play as a central to catch data? lbs-throughput.pcapng nus_thoughput.pcapng

[Stefan Birnir Sverrisson]

Hi

Perhaps this blog post will give you some hints on the subject.

Update 13.10.2014 Try the throughput test example which is linked to in the blog post. The Nexus 7 might not be able to receive more than 1 packet per connection interval, and that might be the problem, but the best way to find out is to sniff the on air traffic to see what is actually going on.

For best throughput, make sure you have selected 7.5ms connection interval in the nRF51 application.