Bluetooth low energy data transfer rate

Jacktang

Bluetooth low energy data transfer rate [Copy link]

BLE Data Rate In the project, we encountered a requirement to transmit tens to more than 100 kB of data via BLE. In actual testing, we found that the average BLE Data Rate was about 2kB/s, so a data transmission took more than a minute at most. This time is relatively long for consumers, and the user experience is not good, so we hope to increase the BLE Data Rate and reduce the data transmission time. Therefore, we conducted a special study on BLE Data Rate. During the research process, we found some relatively good research results in English and Traditional Chinese, so we do not intend to write an in-depth and comprehensive research result by ourselves. We only briefly summarize the relevant points of BLE Data Rate here and provide some links to in-depth research results. 1. BLE Data Rate is affected by many complex factors. It is possible to increase BLE Data Rate by modifying some BLE connection parameters. 2. Factors that affect BLE Data Rate mainly include: * The data rate limit of the other BLE device. The maximum data rate that can be achieved depends on the slowest device of the two devices. * BLE connection parameters, including connection interval, slave latency, connection supervision timeout, packets per connection interval. Data Rate can be increased by modifying these parameters. * The size of MTU (Maximum Transfer Unit). Increasing MTU can reduce the overhead of packet header on data rate, but the Bluetooth protocol stack of some devices does not support modifying MTU. * The speed limit of BLE chip solution. The computing power of MCU will affect data throughput. * The limitations of some mobile phone operating systems, such as iOS has restrictions on BLE connection parameters. The maximum theoretical data rate specified in the spec cannot be achieved on iOS; various Android phone manufacturers have also modified BLE connection parameters, and the maximum BLE Data Rate of different Android phones is different. * Interference from other wireless signals, such as WiFi and Bluetooth working in the same frequency band, will interfere with Bluetooth, increase the bit error rate, increase the number of retransmissions, and reduce the data rate. 3. The increase in BLE Data Rate will increase power consumption, so when large blocks of data are not transmitted, the BLE connection parameters should be restored to balanced mode or energy-saving mode. 4. Starting from Android 5.0, two APIs have been added to adjust BLE connection parameters and MTU: BluetoothGatt::requestConnectionPriority(int connectionPriority) and BluetoothGatt::requestMtu(int mtu). It should be noted that BluetoothGattServer does not support these two APIs because core spece stipulates that only Gatt Client can initiate requests. 5. The latest Bluetooth 5.0 doubles the BLE data rate, but devices that support Bluetooth 5.0 will not be available until 2017 at the earliest.