This blog captures the BLE GATT throughput rates obtained with CYW208xx device in two scenarios, first scenario is where we have only BLE traffic in the 2.4 GHz frequency band and second scenario is where we have both WLAN and BLE sharing the medium. Before diving into the performance rates obtained, let us understand more about BLE GATT Throughput which is the performance criteria considered for the measurements.

CYW208xx Cypress device is qualified for the Bluetooth 5.0 standard. Bluetooth 5.0 claims a maximum BLE throughput of 2 Mbps. But in a practical case, in a BLE data packet, if we consider only the payload (the application data which we wish to send to the other device) and remove the header bytes which get added from lower layers of the BLE stack in the packet, the maximum throughput we get is less than 2 Mbps. We can understand it like this:

 

GATT throughput is a reflection of application data that can be sent or received per second using BLE.

 

There are certain BLE parameters which we must tune to get maximum BLE data throughput. For example, if both the communicating devices support 2M PHY, we can get double the data rate compared to 1M PHY. Connection Interval, Data Length Extension, ATT MTU are some other major factors which decide the throughput we obtain. To understand more about GATT throughput, the BLE parameters and how they control the throughput, refer BLE Throughput Measurement Code example and the associated README document from Cypress.

Now that we have a picture of performance criteria, let us move on and see the Throughput rates obtained with CYW208xx.

 

Scenario 1: BLE traffic in the medium, between two CYW208xx devices 

In this scenario, we measure BLE throughput between two CYW208xx devices. One is configured as GAP Peripheral/GATT Server, another is configured as GAP Central/GATT Client. The below measurements are carried out in a typical office environment. Throughput is measured for three cases:

 

Case 1: GATT Server TX – GATT Client RX

GATT Server continuously sends GATT notifications to GATT Client device. A GATT Throughput of 1335 Kbps is obtained in this case.

Case1_tput.PNG

 

Case 2: GATT Server RX – GATT Client TX

GATT Client continuously writes data into GATT Server data base. A GATT Throughput of 1335 Kbps is obtained in this case.

Case2_tput.PNG

 

Case 3: GATT Server TX/RX – GATT Client RX/TX

This case is a mixture of case 1 and 2. GATT Server continuously sends notifications and GATT Client continuously writes into GATT Server’s data base. In this case, each device simultaneously sends and receives data. A GATT Throughput of 745 Kbps is obtained in this case.

Case3_tput.PNG

 

Scenario 2: WLAN and BLE using Cypress Serial Enhanced Coexistence Interface (SECI)

This scenario is an example to show the rates in a Wi-Fi/BT co-existence environment. The setup consists of a Cypress wireless SoC CYW54907 with CYW20819. The two chips use SECI to communicate and utilize the air medium optimally. To get decent WLAN rates, while using BLE Throughput measurement application, BLE throughput is set to around 20 Kbps by changing PHY and MTU. Note that, according to user application, both the WLAN and BLE rates can be tuned according to requirement. Effective usage of bandwidth is important in co-ex cases rather than obtaining maximum throughput.  

 

seci.PNG

Case 1:  Wi-Fi TCP data download and upload

WLAN TCP data throughput obtained with both BLE GATT Server and GATT Client throughput measurement application tuned at 18 – 20 Kbps.

The following table shows the rates obtained:

 

Use Case

Data Traffic

WLAN Throughput in Mbps

BLE Throughput in Kbps

1

Wi-Fi TCP data download + BLE GATT Server TX

30

18

2

Wi-Fi TCP data upload      + BLE GATT Server TX

40

18

3

Wi-Fi TCP data download + BLE GATT Server RX

29

19

4

Wi-Fi TCP data upload      + BLE GATT Server RX

38

19

5

Wi-Fi TCP data download + BLE GATT Client TX

29

20

6

Wi-Fi TCP data upload      + BLE GATT Client TX

35

20

7

Wi-Fi TCP data download + BLE GATT Client RX

30

18

8

Wi-Fi TCP data upload      + BLE GATT Client RX

37

18

 

 

Case 2: Wi-Fi UDP data download and upload

WLAN UDP data throughput obtained with both BLE GATT Server and GATT Client throughput measurement application tuned at 18 – 20 Kbps.

The following table shows the rates obtained:

 

Use case

Data Traffic

WLAN Throughput in Mbps

BLE Throughput in Kbps

1

Wi-Fi UDP data download + BLE GATT Server TX

43

18

2

Wi-Fi UDP data upload      + BLE GATT Server TX

51

18

3

Wi-Fi UDP data download + BLE GATT Server RX

42

19

4

Wi-Fi UDP data upload      + BLE GATT Server RX

49

19

5

Wi-Fi UDP data download + BLE GATT Client TX

47

17

6

Wi-Fi UDP data upload      + BLE GATT Client TX

49

18

7

Wi-Fi UDP data download + BLE GATT Client RX

43

17

8

Wi-Fi UDP data upload      + BLE GATT Client RX

49

18