Composition of Bluetooth BR/EDR Node

You can create Bluetooth Central and Peripheral basic rate/enhanced data rate (BR/EDR) nodes with Bluetooth® Toolbox by using the bluetoothNode object. These Bluetooth nodes contain a traffic manager and a protocol stack that comprises the baseband, and physical (PHY) layers, as illustrated in the figure. This topic outlines the functionalities implemented by the bluetoothNode object.

To use the bluetoothNode object, you must download the Communications Toolbox Wireless Network Simulation Library. For more information on installing add-ons, see Get and Manage Add-Ons.

Traffic

To model real-world data traffic, the traffic manager employs the networkTrafficOnOff traffic pattern object from the Communications Toolbox™ Wireless Network Simulation Library. Use the addTrafficSource function to add a data traffic source to the bluetoothNode node. The networkTrafficOnOff object allows you to create various traffic patterns. For an example, see Generate Periodic, Bursty, and Random Traffic in Wireless Network.

Baseband Layer

The baseband layer of a BR/EDR node has these functionalities:

  • Transmits and receives asynchronous connection-oriented logical transport (ACL) or Synchronous Connection-Oriented (SCO) packets. ACL uses an acknowledgment and negative acknowledgment (ACK and NACK) mechanism for transmission and reception.

  • Uses a scheduler at a Central node for ACL data transmission to multiple Peripherals. You can use the configureScheduler object function to configure the scheduler. This object function employs round-robin strategy.

  • Employs adaptive frequency hopping (AFH) to select channels for data communication over a link.

  • Classifies a channel as used or unused, where used indicates a suitable channel for transmission and unused indicates a unsuitable channel for transmission. Based on this classification, a channel map is generated. Using the classified channel map, the updateChannelList object function updates the channels for the physical link between the two Bluetooth BR/EDR nodes: the source node and the specified destination node. For more information about channel classification, see Bluetooth BR/EDR Data and Voice Communication with WLAN Signal Interference.

  • Supports a connection supervision timeout. The supervision timeout represents the maximum time a connection can elapse without receiving any valid packets before the node consider the connection lost.

  • Checks for duplicate packets to prevent redundant processing, acknowledges received data, and retransmits any packets lacking acknowledgment using the ACK and NAK mechanism.

  • Forwards the received payload to higher layers for further processing.

To set the baseband connection configuration parameters for a BR/EDR Central and Peripheral node pair, use the bluetoothConnectionConfig object.

PHY Layer

The bluetoothNode node supports full PHY processing, with this section detailing the transmitter and receiver operations it implements.

Transmitter

At the transmitter, the PHY layer involves these operations, as illustrated in this figure.

  • Generates packet headers using the control flag bits, computes a header error check (HEC) code, and attaches it to the header.

  • Generates the protocol data unit (PDU).

  • Whitens the data.

  • Applies forward error correction to the whitened data.

  • Modulates the whitened data using Gaussian frequency shift keying (GFSK) or differential phase shift keying (DPSK).

Receiver

At the receiver, the PHY layer performs these operations, as illustrated in this figure.

Interference Modeling

Bluetooth interference occurs when another signal in the same unlicensed 2.4 GHz band interferes with a Bluetooth signal or when a Bluetooth signal interferes with another signal in that band. In the case of Interference modeling, the bluetoothNode node supports these modes:

  • Overlapping adjacent channel — Considers any signal that overlaps in both time and frequency with the signal of interest as interference.

  • Non-overlapping adjacent channel — Regards signals as interference if they temporally overlap with the signal of interest and their frequencies lie within the range [f1 – fd, f2 + fd], where f1 and f2 denote the start and end frequencies of the signal of interest, respectively, and fd represents the maximum interference offset.

You can configure these interference modes using the InterferenceModeling and MaxInterferenceOffset properties of the bluetoothNode object.

Decoding

The decoding of the received waveform involves these preparations:

  • Applies a low-pass anti-aliasing filter to the received waveform

  • Decodes access code and header using these steps.

    • Separates the access code from the packet header.

    • Demodulates the initial segment of the received waveform to decode the access code.

    • Retrieves the lower address part (LAP) using the decoded access code.

    • If the packet header is present, perform data dewhitening on the header. Then, perform 1/3 rate repetitive decoding on the packet header."

    • Performs a header error check (HEC) on the packet header.

  • Decodes the payload using these steps.

    • Performs a header error check (HEC) on the packet header.

    • Demodulates the payload using the GFSK or DPSK technique.

    • Applies FEC decoding to the payload.

    • De-whitens the payload data.

    • Decodes the payload.

  • Performs a cyclic redundancy check (CRC).

See Also

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