What Is Bluetooth?
Bluetooth® wireless technology is the air interface intended to replace the cables connecting portable and fixed electronic equipment. Bluetooth device manufacturers have the flexibility to include optional core specification features to optimize and differentiate product offers.
Bluetooth is equated with the implementation specified by the Bluetooth Core Specification group of standards maintained by the Bluetooth Special Interest Group (SIG) industry consortium. Communications Toolbox™ Library for the Bluetooth Protocol functionality enables you to model Bluetooth low energy (BLE) and Bluetooth basic rate/enhanced data rate (BR/EDR) communications system links, as specified in the Core System Package [Low Energy Controller volume], Specification Volume 6. It also enables you to explore variations on implementations for future evolution of the standard. Bluetooth BR/EDR and BLE devices operate in the same unlicensed 2.4 GHz Industrial, Scientific, and Medical (ISM) frequency band as Wi-Fi®.
In Bluetooth BR/EDR, the radio hops in a pseudo-random way on 79 designated Bluetooth channels. Each Bluetooth BR/EDR channel has a bandwidth of 1 MHz. Each frequency is located at (2402 + k) MHz, where k = 0,1,...78.
In BLE, the operating radio frequency is in the range 2.4000 GHz to 2.4835 GHz, inclusive. The channel bandwidth is 2 MHz and the operating band is divided into 40 channels, k = 0, …, 39. The center frequency of the kth channel is located at 2402 + k × 2 MHz.
Network Architecture
Network topologies supported in Bluetooth include point-to-point, broadcast, and mesh connectivity. Point-to-point connectivity is available for devices that operate in Bluetooth BR/EDR or BLE. The broadcast and mesh connection topologies are only supported for BLE devices.
Point-to-Point and Point-to-Multipoint Connection Topology
Devices using point-to-point communication operate in a piconet. Point-to-point piconets define one-to-one device communication links. Examples of point-to-point links are links between PCs or mobile phones and peripherals such as headsets, printers, and fitness trackers. Multiple piconets connect to one another in a scatternet topology. Point-to-multipoint piconets define one to more than one device communication links.
This image shows a scatternet of three piconets. Each piconet shows one device in the role of master (M), with other devices in the slave (S) or idle (I) roles. The image also shows one device (M/S) assigned the master role in one piconet and slave in another piconet.
A scatternet is an ad hoc network consisting of two or more piconets.
A piconet is defined as a connection between two or more Bluetooth devices. Piconets nets are limited to a maximum of eight devices, with one master taking the master role at any given time and seven slaves.
The individual Bluetooth devices assume the role of master, slave, or idle peer devices in a given piconet. An individual Bluetooth device can take the role of a slave in one piconet while taking the role of master in another piconet.
The master device provides the synchronization reference.
The slaves are other devices that synchronize to the clock and frequency hopping pattern of the master.
Other idle devices may be located in a piconet but are not active.
Broadcast Connection Topology
Broadcast piconets establish one-to-many communication links for BLE devices. Examples of broadcast links are retail point-of-interest information, indoor navigation, and asset tracking.
Mesh Connection Topology
Mesh networks establish the option of many-to-many communication links for BLE devices. Mesh topology enables the creation of large-scale device networks. Mesh is ideally suited for control, monitoring, and automation systems that require reliable and secure communication between thousands of devices.
The Bluetooth SIG specifies mesh networking requirements to enable an interoperable many-to-many (m:m) mesh networking solution for Bluetooth Low Energy (LE) wireless technology. Mesh networks are ideally suited for large-scale device networks supporting building automation, sensor networks, asset tracking, and other solutions requiring reliable and secure communication between multiple devices. Bluetooth SIG adopted these specifications.
Mesh Profile Specification – Defines fundamental requirements to enable an interoperable mesh networking solution for Bluetooth LE wireless technology.
Mesh Model Specification – Introduces models, used to define basic functionality of nodes on a mesh network.
Mesh Device Properties – Defines device properties required for the Mesh Model specification.
The Bluetooth Mesh Model Specification defines categories of BLE mesh models. Model categories include
Foundation models
Generic models
Sensors
Time and scenes
Lighting
All devices must implement the foundation models for configuration server and health server. All other models in the model categories are optional and implemented based on the service the BLE device performs.
As described in the Mesh Profile Bluetooth specification, mesh networks operate as managed-flood-based networks. Devices use broadcast channels to transmit messages to other devices, and the messages are relayed forward to other devices extending the range of the original message.
A device that is not a member of a mesh network is referred to as an unprovisioned device. A device that is a member of a mesh network is known as a node. Devices are added to a mesh network by a Provisioner. Nodes in a mesh network share network keys that enable them to receive and to relay messages from other nodes in their network or subnet. Network keys are used to secure and authenticate messages at the network layer. Unprovisioned devices cannot receive messages because they do not have the network key to recover the message.
Bluetooth Products
The Bluetooth SIG defines a Bluetooth product as any product containing an implementation of Bluetooth wireless technology. Bluetooth products are classified as:
Bluetooth End Product
Bluetooth Host Subsystem Product
Bluetooth Controller Subsystem Product
Bluetooth Profile Subsystem Product
Bluetooth Component Product
Bluetooth Development Tool
Bluetooth Test Equipment
The Communications Toolbox Library for the Bluetooth Protocol provides features enabling you to model Bluetooth Host and Controller Subsystem Products fully compliant Bluetooth links with the low energy (LE) core configuration.
Bluetooth Low Energy Core Configuration
The Bluetooth Core Specification, Volume 0, Part B, Section 4.4 specifies a set of required features that must be implemented to model fully compliant Bluetooth links with the low energy (LE) core configuration.
The LE core configuration defines three main layers - Application, Host, and Controller. The Communications Toolbox Library for the Bluetooth Protocol provides features to model the host and controller layers. Requirements defined in the Bluetooth Core Specification for the host and controller include
| Layer | Sublayer | Bluetooth Specification Volume | Required Features |
|---|---|---|---|
Host | Logical link control and adaptation protocol (L2CAP) | Volume 3, part A | If the GAP Peripheral or Central role is supported, L2CAP LE Signaling Channel (CID 0x0005) and all mandatory features associated with it. |
Generic access profile (GAP) | Volume 3, part C | All mandatory features for at least one of the LE GAP roles (Broadcaster, Observer, Peripheral, or Central) in sections 9–12 and section 15. | |
Attribute profile (ATT) | Volume 3, part F | If the GAP Peripheral or Central role is supported, all mandatory features. | |
Generic attribute profile (GATT) | Volume 3, part G | GATT is mandatory when ATT is supported. When supported, all mandatory features. | |
Security manager (SM) | Volume 3, part H | If the GAP Peripheral or Central role is supported, all mandatory features. | |
Controller | Physical (PHY) | Volume 6, part A | All mandatory features. |
Link layer (LL) | Volume 6, part B | All mandatory features. |
For a description of the mapping between Bluetooth protocol stack functionality and the OSI reference model, see Bluetooth Protocol Stack.
References
[2] "Bluetooth Core Specification." Bluetooth Special Interest Group (SIG).
[3] "Supplement to the Bluetooth Core Specification, CSS Version 7." Bluetooth Special Interest Group (SIG).
[4] "Bluetooth Core Specification Addendum 6." Bluetooth Special Interest Group (SIG).
[5] "Mesh Profile Bluetooth Specification." Bluetooth Special Interest Group (SIG).
[6] "Mesh Model Bluetooth Specification." Bluetooth Special Interest Group (SIG).
[7] "Mesh Device Properties Bluetooth Specification." Bluetooth Special Interest Group (SIG).