The differences between BLE 4.0, BLE 4.1, BLE 4.2, and BLE 5.

A previous announcement of Bluetooth SIG indicated that with the promulgation and implementation of the new Bluetooth standards, the previous standards will be phased out.

In order to encourage members to gradually abandon the old Bluetooth standards and choose the new Bluetooth standards to improve interoperability and quality, the Bluetooth SIG board of directors officially approved the plan of abandonment and revocation of Bluetooth core specifications.

The Bluetooth core specifications v2.0 / v2.0 + EDR were abandoned from December 19th, 2017.

The Bluetooth core specifications v2.0 / v2.0 + EDR were withdrawn from July 1st, 2018.

The Bluetooth core specifications v4.0 / v3.0 / v2.1 / v2.1 + EDR were abandoned from July 1st, 2018.

The Bluetooth core specifications v4.0 / v3.0 / v2.1 / v2.1 + EDR were withdrawn from January 1st, 2020.

The Bluetooth core specification v4.1 was abandoned from January 1st, 2019.

The Bluetooth core specification v4.1 was withdrawn from July 1st, 2020.

The Bluetooth certification announcement reminds me of the routine of Andy Beer’s Law, “What Andy gives, Bill takes away”. With the high-speed development of semiconductors and the more and more powerful processors, there will be more hardware resources that can be used to run more complex Bluetooth protocols and software. SIG issues new standards and adds new functions every year, which requires more hardware resources to run more complex algorithms and protocols. Therefore, the old hardware that can't support the new software will be eliminated.

After Bluetooth v4.0, there are two parts of Bluetooth, classic Bluetooth and Bluetooth Low Energy. This article reviews the past and future of BLE and focuses on the differences between Bluetooth v4.0 and afterwards.

Bluetooth v4.1 vs Bluetooth v4.0

1. Improve Data Transfer Rate

Compared with Bluetooth v4.0, the maximum of single-packet data transfer of Bluetooth v4.1 is increased from 20 bytes to 23 bytes, which increases the data transfer rate by 15%. According to the regulation, the payload value of the single-packet data can be modified, and then verify which Bluetooth core specification your device is. If the chip only supports Bluetooth v4.0, the data transfer of 23 bytes will result in compilation errors or packet loss during transmission.

2. Master-Slave Coexistence

For Bluetooth v4.1, the Link layer topology has been updated to allow master-slave coexistence in a single device (time slice rotation mode), and it also supports one-master multi-slave connection topology.

3. Support 32-Bit UUID

Bluetooth v4.1 supports 32-bit UUID which refers to the UUID carried in the broadcast packet. The 32-bit UUID here is not the 16-bit UUID and 128-bit UUID of the attribute list. The full 128-bit UUID can be obtained by the 32-bit UUID mapping of the broadcast so that the larger effective broadcast data length in the broadcast packet can be got.

Bluetooth v4.1 vs Bluetooth v4.2

1. LE Connection Security

Learned from the Specification definition, the pairing encryption modes of Bluetooth v4.0 and v4.1 are based on AES-CCM encryption. However, because the receiver and transmitter of Bluetooth v4.1 share the same key, there is risk and vulnerability of being cracked. The pairing of Bluetooth v4.2 is encrypted by the Diffie-Hellman Key Exchange algorithm. Each device has a pair of key pairs, including a public key and a private key. The private key is saved by itself, and the public key is disclosed to the other party. When data is exchanged, one party encrypts the file with its own private key and the other party's public key, and the receiver uses its own private key and the transmitter's public key to decrypt the file, thereby effectively preventing the middleman from cracking the key.

2. Privacy Protection

Bluetooth will carry its own Bluetooth Device Address (abbreviated as the BD_ADDR) during the broadcast process. BD_ADDR is the only MAC address of Bluetooth. BD_ADDR will play a role in identifying Bluetooth devices such as pairing and connecting. It is very helpful in logistics tracking applications. The logistics equipment can be tracked according to BD_ADDR. However, the BD_ADDR is not expected to be exposed to the monitoring of the master device in some applications. In this case, Bluetooth v4.2 provides a flexible choice that either Public Device Address or Random Device Address can be used as you want. That is, the slave device can choose to send a Random Device Address in the broadcast mode so that the master device can obtain its real BD_ADDR after paired and parsed. In addition, the BD_ADDR of the device in the broadcast mode is a random sequence.

3. Broadcast Data Capacity

Bluetooth v4.1 supports a maximum of 23 bytes of single packet data transfer, however, Bluetooth v4.2 supports a maximum packet of 255 bytes, which greatly improves the data transfer rate. 

Bluetooth v4.2 vs Bluetooth v5.0

1. 4X the Range

With the help of forwarding error correction codes and pattern mapping, the RX improves the error correction ability of the whole payload packet in the process of Bluetooth data transfer (in short, to improve the RX receiving sensitivity), and the transmission distance of Bluetooth v5.0 can be significantly improved. The 4X range is achieved by scaling down the data rate in 4 steps: 2 Mbps, 1 Mbps, 500 kbps, and 125 kbps. The lower the data rate, the longer the range achieved.

2. 8X the Broadcast Capability

According to Bluetooth 4.x protocol, each advertising packet only supports 31-byte data, and the broadcast channel is limited to 37, 38, and 39 channels. On the basis of the original PDU (ADV_IND, ADV_DIRECT_IND, ADV_NONCONN_IND, and ADV_SCAN_IND. Called legacy PDUs) used to transmit broadcast data, Bluetooth v5.0 adds an extended PDU (ADV_EXT_IND, AUX_ADV_IND, AUX_SYNC_IND, and AUX_CHAIN_IND. Called extended advertising PDUs), and also allows Bluetooth to send data with a length of 0 ~ 255 bytes on 37 channels other than 37, 38 and 39 channels.

3. 2X the Data Rate

Compared with Bluetooth v4.2, Bluetooth v5 supports two PHYs, including 1M PHY and 2M PHY. The data rate of 2M PHY is a new feature of Bluetooth v5.0. Before Bluetooth v4.2, only a 1M PHY rate is supported. Like Bluetooth v4.2, Bluetooth v5 also supports a single packet of 255 bytes of data transmission. This means it can reach a net data rate of about 1.6 Mbps with overhead. 

In general，there are still a large number of Bluetooth v4.0/v3.0/v2.1/v2.0+EDR products on the market. Because of its function and low price, it is loved by customers of fast-moving consumer goods, such as selfies, remote control, and various smart devices. For industrial and automotive applications, Bluetooth v4.0 products are still in the lead. The reason is that they are stable, well supplied and cheap. However, The Bluetooth before Bluetooth v5.0 solves the problem of a single point connection between wearable devices and mobile phones, then Bluetooth v5.0 is to solve the problem of multi-point interconnection IoT.

Hello future, hello Bluetooth 5.