Increasing the communication rate using GATT-READ above 10kB/s (K Bytes/Seconds) ?

[Omid]

Hello my friends,

I am trying to convey a large system file data using my own developed GATT Service where I am using a read characteristic to read the file system.

Specifically, I have a central which does gat read on the discovered attribute handle exposed by the peripheral. (The read characteristic included in the GATT service).

After doing MTU update, I can achieve almost 2.55 KB/s where I have the following related configurations:

CONFIG_BT=y
CONFIG_BT_SMP=y
CONFIG_BT_TINYCRYPT_ECC=y
CONFIG_BT_MAX_PAIRED=2
CONFIG_BT_HOST_CCM=y
CONFIG_SETTINGS=y

CONFIG_BT_HCI_ACL_FLOW_CONTROL=y
CONFIG_BT_L2CAP_DYNAMIC_CHANNEL=y
CONFIG_BT_L2CAP_TX_MTU=251
CONFIG_BT_BUF_ACL_RX_SIZE=255
CONFIG_BT_BUF_ACL_TX_SIZE=251
CONFIG_BT_BUF_CMD_TX_SIZE=255
CONFIG_BT_CTLR_DATA_LENGTH_MAX=251

Also, here is the connection parameters I am using:

    struct bt_le_conn_param param = {
                            .interval_min = 0x0008,
                            .interval_max = 0x0008,
                            .latency = (0x00008 * 1.25)*1,
                            .timeout = 400,
                            };

However, I have seen posts in devzone like THIS ANSWER or THIS POST where people are talking about transmission rates around 14 KB/s or at least above 10KB/s.

I was wondering how I can increase the download rate of my application to such ranges?


Thanks,
Omid

[Omid]

I found out what was causing the issue.
Apparently, the connection parameter update did not work out the way I intended to.
For some reason, the connection parameters reverted back to some random value.
I moved the param update after MTU exchange phase, and then, it got solved.
As a matter of fact, I can get a reading rate of 12.7 KBytes/seconds with a connection interval of 8 ms.

I am going to keep the question open to see if there is any other suggestions that I can use to improve the rate further.