Analysis of the Maximum Achievable Throughput of Extended Advertisements in BLE

Bluetooth low energy (BLE) allows connectionless data transfer to take place through advertisements. Bluetooth Core Specification version 5.0 introduced extended advertising which allows each secondary channel advertising packet to carry up to 255 bytes of payload. Up to 1650 bytes of data can be advertised as a single transmission through chaining of multiple packets carrying fragments of advertising data. This article derives throughput expression in the presence of bit errors and analyses the maximum throughput for connectionless data transfer using extended advertisements, for all the Uncoded and Coded PHYs that offer different data rate and range capabilities. Guidelines are provided for the choice of appropriate PHYs based on the transmission size, throughput, and range requirement of the application. Simulation results have been presented that verify the analytically obtained throughput values. Since connectionless mode of communication does not allow acknowledgments from the receiver, it is essential to overcome the impact of bit errors through retransmission of each packet for increased chances of its reception. Analysis of maximum achievable throughput with retransmission of each data packet has also been presented in this article. Results suggest that the maximum achievable throughput is impacted by the duration of each transmission, due to which beyond a certain value of the data size, the low energy (LE) Coded PHYs are unable to offer significant improvement in the amount of data delivered per unit time.