Understanding Concurrent Multiprotocol: An In-Depth Exploration
As wireless communications continue to evolve, the demand for devices that can support multiple protocols simultaneously has grown significantly. This capability, known as concurrent multiprotocol (CMP), allows devices to operate across different wireless standards at the same time, increasing their versatility and adaptability. CMP is a benefit because while devices can traditionally handle multiple protocols, this often requires incorporating multiple radio ICs. CMP simplifies this by enabling devices to achieve the same functionality with just a single radio IC, making it more cost-effective for developers. In this blog, we will dive into the concept of CMP and examine the distinctions between CMP - single channel, CMP with concurrent listening, and CMP with Bluetooth Low Energy (LE) Dynamic Multiprotocol (DMP).
Concurrent Multiprotocol CMP: Single Channel
CMP allows a device to support multiple wireless protocols simultaneously that are based on the same IEEE 802.15.4 standard, such as Zigbee and Thread.
By sharing the 802.15.4 PHY and MAC layers, and with Zigbee and Thread operating on the same channel, this feature enables the device to concurrently receive Zigbee or Thread packets using a single radio (and no time slicing). It achieves the differentiation between the protocols through the unique PANID associated with each protocol stack, a functionality referred to as the Multi-PAN feature.
The key advantage of CMP lies in its simplicity and ability to operate on multiple networks with no decrease in performance other than medium congestion.
- Ability to support multiple IEEE 802.15.4 protocols such as Zigbee and Thread operating on the same channel
- True concurrency (no time slicing)
- Rx frames differentiated by PAN IDs
- Channel access managed by normal 802.15.4 CSMA-CA
- Functional in SoC, (selective) NCP and RCP modes
Concurrent Multiprotocol with Concurrent Listening
Concurrent multiprotocol with concurrent listening takes the concept a step further by allowing the device to support multiple wireless protocols operating on independent channels simultaneously.
With the radio rapidly switching between the two operating channels (in the order of tens of microseconds) to detect incoming packets, CMP with concurrent listening allows the device to concurrently listen for Zigbee and/or Thread packets on their respective channels using a single radio and no blocking window.
This is particularly useful in scenarios where a single device needs to be a part of two separate mesh networks operating on different channels. For example, with concurrent listening, a central hub in a smart home environment, that is part of multiple mesh networks can simultaneously monitor signals from various sensors, ensuring timely and precise responses to events such as motion detection or temperature changes. Another key advantage of concurrent listening is its seamless extension to the single channel case (discussed above).
This approach requires more sophisticated hardware and software, with the tradeoff of slightly reduced Rx sensitivity.
- Ability to support multiple IEEE 802.15.4 protocols such as Zigbee and Thread operating on different channels
- Rapid switching between two operating channels
- RX frames differentiated by PAN IDs
- Channel access managed by normal 802.15.4 CSMA-CA
- Functional in SoC and RCP modes
Example of Concurrent Multiprotocol with Concurrent Listening:
- Device rapidly switches between the two operating channels every 48 us
- When a valid 802.15.4 preamble is detected
- Stays on channel to receive the entire packet
- Checks to see if it is a valid packet for the network and device
- Transmits acknowledgement (if required)
- Switches to the next channel and repeats the process
Concurrent Multiprotocol with Bluetooth LE Dynamic Multiprotocol
Concurrent multiprotocol with concurrent listening when combined with Dynamic Multiprotocol (DMP) allows support for three protocols such as Zigbee, OpenThread and Bluetooth LE simultaneously.
It extends the same concept of dynamic multiprotocol support with Bluetooth LE (in a single protocol case such as Zigbee) to a concurrent multiprotocol case (supporting both Zigbee and Thread), where you do not shutdown or de-initialize the entire protocol stack; instead, you keep running a separate (in this case, a third) protocol stack such as Bluetooth LE through time-slicing or time-sharing, where the device would allocate specific time slots for the Bluetooth LE connection.
By periodically swapping the Bluetooth LE PHY with the 802.15.4 PHY, it allows Bluetooth LE connections to remain active, and at the same time stay connected on the Zigbee and Thread networks. This allows the node to respond to either a command via Zigbee, Thread, or Bluetooth.
With a single radio supporting three protocols, careful management of the DMP configuration based on the application requirements becomes critical to ensure optimum performance.
- Extends Bluetooth LE DMP to concurrent multiprotocol
- Bluetooth LE continues to operate in time-sliced DMP mode, interrupting CMP (Zigbee + Thread) as needed.
- With concurrent listening enabled (for Zigbee and Thread to operate on separate channels), the radio rapidly switches between the two 15.4 channels, while switching to Bluetooth LE channel as configured.
- Does not impact BLE performance (if Bluetooth LE is set as a higher priority)
Current Offerings
Concurrent Multiprotocol - Single Channel
- Enables Zigbee and Thread support on the same 15.4 channel
- Optionally supports Bluetooth LE in DMP mode
- Supported in RCP mode (on Series-1) and SoC, NCP, and RCP modes (on Series-2)
Concurrent Multiprotocol with Concurrent Listening
- Enables Zigbee and Thread support on separate 15.4 channels
- Optionally support Bluetooth LE in DMP mode
- Supported only on Series-2 in RCP (MG21 and MG24) and SoC mode (MG26 – with Matter integrated)
Combining CMP technology with DMP solutions provides versatile options to address the varied demands of modern wireless communication systems. The choice between these approaches depends on the specific needs of your application.
For scenarios where simplicity and strict concurrency without compromising Rx sensitivity are critical, the CMP in a single-channel setup may suffice. In contrast, applications requiring support for separate 15.4 channels in wireless mesh networks may benefit from CMP with concurrent listening. Lastly, for applications demanding maximum flexibility, including support for Bluetooth LE alongside 15.4 mesh networks, CMP with Bluetooth LE DMP is the optimal choice.
By understanding these approaches and their distinctions, you can make an informed decision to select the most suitable technology, ensuring superior performance and reliability for your application.
