Re: data transmission rate...to slow...

Subject: Re: data transmission rate...to slow...
From: Matthew Chung <email@hidden>
Date: Tue, 28 May 2013 08:24:14 -0700

Hi Etan,

I was wondering if it's ok if I ask a quick question regarding your hardware. I'm sending data from ios (peripheral) to a TI cc2540 (central) using subscriptions and getting 5-6kbps. However, my ios to ios tests gave about 20ish kbps.

The tests from your graph http://www.scriptreactor.com/conn_interval-throughput.pdf are not using the TI cc2540 are they? If not, can you share what bluetooth hardware you are using?

On Sun, May 12, 2013 at 1:12 AM, Etan Kissling <email@hidden> wrote:

William,

I have used a dedicated peripheral where the connection interval can be chosen more fine-grained.

With an iDevice taking the peripheral role, such speeds cannot yet be achieved with public APIs as of iOS 6.1.4.

Etan
On 12.05.2013, at 07:26, "William Henderson" <email@hidden> wrote:
For reference, what I'm seeing is that no mater how fast I send packets (from the central), the peripheral only receives a packet every 60ms. With a 20b packet that's about .33kb/s.

This is with CBPeripheralManagerConnectionLatencyLow.

--

William Henderson

Sent from my iPhone

On Saturday, May 11, 2013 at 10:00 PM, William Henderson wrote:
Etan,

Which direction were you sending in? I'm not seeing anything near that rate when going from central->peripheral (using writewithoutresponse, scanning off, advertising off)...

William

Frederic, there is only one packet of up to ~20 bytes transmitted every two connection events if you use reliable data transfer. If you want to increase that to ~ four packets every connection event, you have to use unreliable data transfer (WriteWithoutResponse / Notification) and have to add reliability in your app layer. Note that WiFi interferes with BLE, disabling it should net you a small boost in throughput. These are the throughputs I could achieve with iPhone as central and dedicated peripheral: http://www.scriptreactor.com/conn_interval-throughput.pdf Etan

I have made some tests to exchange data between 2 iDevices (iOS6 iPad3/iPhone5) using CBPeripheralManagerConnectionLatencyLow settings.

The maximum rate I have is 1135 bytes / s (1.1KB/s)

- Is it possible to get better speed ?

- What is the maximum I can have with iOS stack ?

From some documents:

BLE: 200kbits/s -> 25KB/s

NFC: 424kbits/s

Why is the difference so huge (20x slower) ?

Fred
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Regards,
Matthew

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Follow-Ups:
- Re: data transmission rate...to slow...
  - From: Etan Kissling <email@hidden>

References:
	>data transmission rate...to slow... (From: William Henderson <email@hidden>)
	>Re: data transmission rate...to slow... (From: William Henderson <email@hidden>)
	>Re: data transmission rate...to slow... (From: Etan Kissling <email@hidden>)

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