Shulou(Shulou.com)06/02 Report--

BT 5.0 New Features Overview 1.1. Preface

On December 6, 2016, Bluetooth SIG released version 5.0 of the core specification, which enhances BLE in terms of distance, speed and other aspects. The Bluetooth official website is summarized as follows:

With the launch of Bluetooth 5, Bluetooth ®technology continues to evolve to meet the needs of the industry as the global wireless standard for simple, secure connectivity. With 4x range, 2x speed and8x broadcasting message capacity, the enhancements of Bluetooth 5 focus on increasing the functionality of Bluetooth for the IoT. These features, along with improved interoperability and coexistence with other wireless technologies, continue to advance the IoT experience by enabling simple and effortless interactions across the vast range of connected devices.

Compared to Bluetooth 4.2, new features include:

Slot Availability Mask (SAM) 2 Msym/s PHY for LELE Long RangeHigh Duty Cycle Non-Connectable AdvertisingLE Advertising ExtensionsLE Channel Selection Algorithm # 2

In addition, 5. 0 removes park mode. 1.2.Slot Availability Mask (SAM)

Let two Bluetooth devices know each other about their available slots.

Example 1: now many wireless modules are integrated with Bluetooth WIFI, and there will be many conflicts, such as wireless frequency band and MCU resources. Bluetooth itself has a collision prevention protocol (MWSMobileWirelessStandards). For example, the current wifi is being downloaded. The protocol tells the Bluetooth module that you cannot use Bluetooth at this time, but the peer device does not know that your phone's Bluetooth cannot be used, so it can use the SAM feature to exchange information and know that it cannot be used.

Example 2: the Bluetooth of a mobile phone can connect multiple Bluetooth devices. For example, I connect three bracelet ABC. When the phone interacts with A, it cannot interact with B. the previous practice is that we allocate resources when we connect, when to interact with An and when to interact with B. the problem is

1) the resources required by ABC are different in different periods. When A downloads firmware in OTA, it obviously needs more solts resources, but because the phone has been allocated through planned economy at the time of connection, no matter whether you live or die later.

2) ABC's resource allocation is basically up to the phone, so there is little room for discussion with ABC at all. This feature solves this problem. In the future, we can discuss and pay attention to democracy. My phone vows to defend to the death the right of your ABC device to speak.

1.3. 2 Msym/s PHY for LE

Based on the PHY of Bluetooth 4.21m symbol rate (symbol rate) (called LE 1m PHY), add a 2m symbol rate PHY (called LE 2m PHY). The differences between the two are as follows:

1) the symbol rate of LE 1m PHY is 1Msym/s, which is a required PHY (each LE device must support it) and supports ECC (error correction coding, optional). According to different encoding methods, three bit rates are supported: 1Mb/s (LE 1m), 500Bb/s (LE Coded) and 125Kb/s (LE Coded).

2) the symbol rate of LE 2m PHY is 2Msym/s, which is optional PHY, ECC (error correction coding) is not supported, and the bit rate is 2Mb/s (LE 2m unsigned).

1.4.LE Long Range

Increase the maximum transmission power from 10mW in 4.0 to 4.2 to 100mW of 5.0. With regard to the transmit power of BLE, there is a table in spec:

1.5.High Duty Cycle Non-Connectable Advertising

Bluetooth 4.0 limits the minimum advInterval of both Scannable Undirected and Non-connectable Undirected Advertising Event to 100ms, which limits the maximum rate of BLE broadcasting (2.48kbps). Bluetooth 5.0 is no longer treated differently, and the minimum value is uniformly limited to 20ms. In theory, the highest broadcast rate can be increased by 5 times (12.4kbps).

1.6.LE Advertising Extensions

The broadcast channel of Bluetooth 4.0Accord 4.1Compact 4.2 is relatively simple, with 3 (or less) Physical Channel directly reserved for Advertising Event transmission. The length of transferable data is 6-37 octets (plus protocol overhead).

Bluetooth 5.0, on the other hand, has come up with a new trick (a great increase in practicality and a real connectionless broadcast), which can be summarized as follows:

1) abstract the concepts of primary advertising channel and secondary advertising channel.

2) primary advertising channel is Bluetooth 4.2 and earlier, reserved for transmitting Advertising Event.

3) secondary advertising channel, on the other hand, directly reuses the remaining 37 data channel to transmit the extended Advertising Event (called Extended Advertising Event). At this time, the length of data that can be transmitted is 0-255 octets, which is many times higher than the previous 37.

4) therefore, on the basis of the original PDU (ADV_IND, ADV_DIRECT_IND, ADV_NONCONN_IND and ADV_SCAN_IND, called legacy PDUs) for transmitting broadcast data, an extended PDU (ADV_EXT_IND, AUX_ADV_IND, AUX_SYNC_IND and AUX_CHAIN_IND, called extended advertising PDUs) is added.

5) accordingly, Advertising Event is also divided into Legacy Advertising Event and Extenteded Advertising Event.

1.7.LE Channel Selection Algorithm # 2

An improved channel sorting algorithm (CSA#2) is introduced to improve the pseudo-randomness of next-hop channel ordering. CSA#2 will improve the coexistence performance of enabled devices in the presence of WiFi and other Bluetooth devices.

1.8. Summary

For the above six New Features, for Controller software, we focus on the following two points, which we will specifically interpret in detail.

High Duty Cycle Non-Connectable AdvertisingLE Advertising Extensions

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