Ellisys, Mohammad Afaneh, Ellisys
Topics: Megabit, Transmission, Advanced Sensing, Network Technology, Communication Technology
This summary will introduce Bluetooth V and Le coded Phy or long-range mode. Some topics include the definition of coded V, how Phy works when Phy should be used, and finally, real-world test results. Phy needs to be defined. Phy refers to the physical layer in a network model, and in Bluetooth V, the interface between the actual radio hardware and the link layer. Bluetooth Low Energy has three V’s, and the first is a standard one-megabit file, which was introduced at the beginning of 2010 in version 4.0. The second is the two-megabit V introduced in Bluetooth 5.0. It can be used to achieve a higher speed than the standard one-megabit V. The third and final V, which is the topic for this summary in the coded V, was also introduced in Bluetooth version 5.0 and is used to achieve a more extended range up to four times that standard BLE range. Now let’s talk about what coded means. Coding, in simple terms, is the process of applying redundancy to allow data recovery at the receiver without the need for transmission of the data. So, when data gets corrupted during the transmission, the receiver can utilize the data redundancy to recover the original data without requesting a rate. An important thing to note is that Phy does not rely on increased transmitting power from the transmitter. But instead, data is sent at the standard one-megabit symbol per second, a transmission rate where multiple symbols represent each bit of data. According to important notes on the coded file, the effective data rate also depends on the coding scheme used. First, code Phy is optional in Bluetooth 5.0, which means that not all Bluetooth 5.0 chipsets will support Phy, so make sure to check the technical specs before choosing a Bluetooth chipset for the long-range project. Second, there are two coding schemes available for use: S=2. This means two symbols per data bit which cuts the data rate down to half the standard data rate or 500 kilobits per second. The other is S=8. Phy uses eight symbols for data bit, which reduces the data rate from the standard one-megabit rate now 225 kilobits per second rate. For example, let’s transmit 8 bits and end up using the S=8 scheme, then Phy will have to transfer 64 bits for that 8 bit of data, which means that transfers will increase the radio on time and increase power consumption with the coded Phy. It is also available for use in both advertising and connection states. Keep in mind that in the advertising state, the device using the coded Phy does not send out the advertising data on the primary advertising channels: 37, 38, and 39 but instead utilizes extended advertisements on the secondary medium. This is how Phy advertisement works. The data goes through two processes before being transmitted from the transmitter to the receiver over the air. The first process gets encoded by a forward error correction encoder, and second, the output of that first process gets spread by a patten mapper. The Phy packet defines the format for both the advertising and data packets. Not all parts of the Payette packet use the same coding; some elements are not coded at all. Finally, Phy makes more sense for applications that require low data rate transfers; otherwise, a significant impact on power consumption and usability will occur.