Bluetooth 5 - Bottom of the technology change
Bluetooth 5 core specifications since December 2016 launched so far, there are many Bluetooth 5.0 products through the Bluetooth certification, facing the market. Bluetooth 5 to promote the rapid development of Internet of things, significantly enhance the Bluetooth transmission distance, speed and broadcast messaging capabilities, making the wireless connection becomes more simple and safe. So, how does Bluetooth 5 upgrade these aspects?
1. Bluetooth 5 new PHY
Bluetooth 5 technology upgrade is based on the new PHY implementation, can be said to be a bottom-up technological innovation. Bluetooth 5 core specifications are LE 1M, LE 2M and LE Coded. What is the difference between these different PHYs, and what are the practical meanings?
LE 1M PHY
For Bluetooth 5, the symbol rate can have multiple choices, but LE 1M is a must-have and must be supported. LE 1M is used in Bluetooth 4 PHY, Bluetooth 5 will also be used, and Bluetooth 5 and Bluetooth 4.2 packet type is the same, the payload is 255 bytes, so when Bluetooth 5 using LE 1M PHY, the throughput, power consumption, transmission distance and so on is the same as Bluetooth 4.2. Compared to the LE section of Bluetooth 4.0 and 4.1, the packet length becomes eight times, allowing more data to be propagated for mesh and other network protocols, providing more flexibility for non-connected applications.
LE 2M PHY
LE 2M PHY is Bluetooth 5 new PHY, without changing the packet type of the case, the original transmission package and receive packets required to reduce the time required for the original half, without considering the case of packet interval time, The theoretical rate of Bluetooth transmission into Bluetooth 4 of the two times for the follow-up of advanced audio, image transmission applications laid a solid foundation.
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According to the Bluetooth technology alliance information, you can see the Bluetooth 5 bandwidth than 4.0 / 4.1 version 4.6 times higher than the 4.2 version of about 1.7 times higher. Higher bandwidth can be converted to higher speed, not only enhance the data transmission speed, optimize the Bluetooth application response time, and further enhance the use of Bluetooth products experience. In the 2M rate, Bluetooth power consumption will increase, relative to the original Bluetooth 4 LE part of the 10dBm power limit, Bluetooth 5 LE power limit at 20dBm, a direct increase of 10 times the power limit. At the transmission distance, LE 2M will be shorter than LE 1M.
LE Coded PHY
Bluetooth 5 is to rely on LE Coded PHY to achieve farther propagation distance, LE Coded PHY is also the use of 1M symbol rate, in order to increase the effective transmission distance of Bluetooth, we must ensure that the farther distance can be achieved and the same can Tolerant bit error rate, but Bluetooth 5 to increase the effective transmission distance without increasing the Bluetooth transmitter power, but to increase the new processing error and error detection mechanism, that is, in the transmission of additional data to the FEC forward Error correction coding, so as to achieve a more effective distance.
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Bluetooth 5 LE Coded PHY is divided into LE Coded S = 2 and LE Coded S = 8 two coding schemes. In S = 2, the FEC code uses the convolutional encoder to output the data bits by one half of the bit rate, that is, two coded bits instead of the original data bits. Under this coding scheme, the theoretical effective data transfer rate is reduced to 500Kb / s, but because of the enhanced error correction capability, increased sensitivity, transmission distance can reach Bluetooth 4 low power consumption 2 times. In S = 8, the data is output at one eighth of the code rate by the convolutional encoder. The eight coded bits are used instead of the original data bits. The theoretical effective data transfer rate is 125Kb / s, the error correction capability and the anti-interference ability are significant Enhanced, transmission distance can reach Bluetooth 4 low power consumption 4 times.
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2. Bluetooth 5 bright prospects
Bluetooth 5's technological innovation will have a significant impact in many areas and will continue to target low-power technologies in the Internet of Things. Through the Bluetooth 5 new HCI (host controller interface) command, you can select different PHYs for transmission and reception, for different application scenarios, you can have better results. Faster transmission rate, you can give users a better experience, farther away from the distance, can cover the entire room or even the entire shopping malls of wireless equipment for the further networking of things brought to the imagination.
