Connectivity Kit Terminology

A

A2DP

Advanced Audio Distribution Profile, which is used to support transmission of high-quality audio, for example, listening to music with a Bluetooth headset. This protocol defines two roles: A2DP source and A2DP sink.

A2DP Sink

An audio sink in the A2DP protocol, which is responsible for decoding and playing audio. Typical devices include Bluetooth headsets and speakers.

A2DP Source

An audio source in the A2DP protocol, which is responsible for encoding and sending audio data. Typical devices include mobile phones and tablets.

ACL

Asynchronous connectionless link, which is used to indicate the connection status of physical links between devices in the Bluetooth subsystem.

B

BLE

Bluetooth Low Energy, which is supported since Bluetooth 4.0. Compared with traditional Bluetooth, BLE features low power consumption and long battery life.

BR

Basic Rate, which is a Bluetooth wireless communication technology representing Bluetooth Classic. It is mainly used in scenarios such as file and audio stream transmission.

Bluetooth SIG

Bluetooth Special Interest Group, which is an organization that releases Bluetooth technical specifications. Developers can obtain detailed Bluetooth technical documentation from their official website.

C

Characteristic

Core data unit of a GATT service. It supports data read/write and is uniquely identified by a UUID.

D

Descriptor

Data unit of a GATT characteristic. It is used to describe the additional information and attributes of the characteristic. It supports data read/write and is uniquely identified by a UUID.

E

EDR

Enhanced Data Rate, which enhances BR by offering a higher data transmission rate. Together with BR, they are collectively referred to as traditional Bluetooth.

G

GATT

Generic Attribute Profile, which is the core protocol of BLE that defines the mechanism for Bluetooth communication and data transmission based on services, characteristics, and descriptors.

H

HF

Hands-Free unit, i.e., the hands-free device in the HFP protocol. It serves as the remote control terminal in Bluetooth call audio, providing a physical interaction interface (e.g., button) and audio input/output (e.g., microphone, speaker). Typical devices include Bluetooth headsets and Bluetooth car kits.

HFP

Hands-Free Profile, which is used to enable hands-free calling between Bluetooth devices, supporting bidirectional voice calls and control functions. This protocol defines two roles: HFP AG and HF.

HFP AG

Hands-Free Audio Gateway, i.e., the audio gateway in the HFP protocol. It serves as the audio processing center in Bluetooth call audio, responsible for call control (such as executing answer/hang-up instructions) and managing audio input/output. Typical devices include mobile phones and tablets.

HID

Human Interface Device Profile, which enables low-latency bidirectional communication between Bluetooth-enabled human-computer interaction devices, such as transmitting data between keyboards, mouse devices, and gamepads, and hosts (e.g., mobile phone, tablet). This protocol is specifically designed for Bluetooth Classic. It defines two roles: HID host and HID device. In the HID protocol, data transmission channels are classified into two types: interrupt transfer channel and control transfer channel. The interrupt transfer channel is used to unidirectionally transmit real-time data in low latency. The control transfer channel is used to bidirectionally transmit reliable real-time data, which includes the following three requests:

• GET_REPORT: data read request initiated by the HID host, which is used to obtain the status information of the HID device.
• SET_REPORT: data write request initiated by the HID host, which is used to send control instructions to the HID device.
• SET_PROTOCOL: protocol mode switching request initiated by the HID host.

HID Device

HID devices that provide human-machine data input/output to the HID host. Typical devices include mouse devices and keyboards.

HID Host

HID host that processes and receives input data from HID devices and performs corresponding operations. Typical devices include mobile phones and tablets.

HOGP

HID over GATT Profile, which is an HID specification implemented based on the GATT protocol of BLE. It ports traditional HID functions to BLE devices for reuse and is compatible with the HID interaction logic of BLE devices such as keyboards, mouse devices, and selfie sticks.

L

L2CAP

Logical Link Control and Adaptation Protocol, which supports diverse transmission requirements of upper-layer protocols and applications by providing both connection-oriented and connectionless data services. This protocol also facilitates multiplexing, segmentation, and reassembly, ensuring efficient and reliable data transfer over Bluetooth connections.

M

MAP

Message Access Profile, which can be used to synchronize data such as SMS and emails between Bluetooth devices. It defines two roles: MCE and MSE.

MCE

Message client equipment, which is the message client in the MAP protocol and can view and manage MSE messages. Typical devices include Bluetooth car kits.

MSE

Message server equipment, which is the message server in the MAP protocol and stores original message data such as SMS messages or emails. Typical devices include mobile phones.

MTU

Maximum transmission unit, which indicates the maximum size of a single data packet transmitted on the network, in bytes.

N

NAP

Network access point in the PAN protocol that serves as the gateway device to provide Internet access or local network sharing functions. Typical devices include mobile phones and tablets.

O

OPP

Object Push Profile, which is built on the Generic Object Exchange Profile (GOEP) to transmit data (such as images and documents) between devices.

P

PAN

Personal Area Network, which implements network sharing between devices. NAP and PANU are two major roles in the protocol.

PANU

Personal area network user in the PAN protocol. As a client device, it proactively connects to the NAP to obtain network services.

PBAP

Phone Book Access Profile, which can be used to synchronize phone book data such as contacts and call logs between Bluetooth devices. This protocol defines two roles: PCE and PSE.

PCE

Phone book client equipment in the PBAP protocol. As the data requester, it can obtain the phone book data of the PSE. Typical devices include Bluetooth car kits.

PSE

Phone book server equipment in the PBAP protocol that stores original phone book data such as contacts and call logs. Typical devices include mobile phones.

Profile

Bluetooth technology protocol or capability in the Bluetooth subsystem, Typical examples include A2DP, HFP, and HID.

PSM

Protocol/service multiplexer, which is used to identify different services or protocols on the L2CAP layer.

R

RFCOMM

Radio Frequency Communication (RFC) protocol, which is designed to simulate traditional RS232 serial communication (a common wired data transmission standard), while providing a simple and reliable data transmission method and supporting multiple concurrently connected channels.

RSSI

Received signal strength indicator. It is used in wireless communications to quantify the signal strength at the receiver in dBm.

S

SDP

Service Discovery Protocol, which is used to discover and identify services provided by other Bluetooth devices.

Service

Bluetooth GATT service, which is a data structure containing multiple characteristics and dependent services. It represents a capability of the BLE device and is identified by a UUID.

SPP

Serial Port Profile, which can be used to implement connection and data transmission between Bluetooth devices.

U

UUID

Universally Unique Identifier, which is a 128-bit string that identifies different Bluetooth profiles, as well as services, characteristics, and descriptors in the GATT protocol.