Maintaining Flexibility with Multiprotocol Wireless Connectivity

Applications for Multiprotocol Connectivity

The usefulness of connected devices in consumer, commercial, and industrial environments can be enhanced or improved through multiprotocol connectivity. In-home automation, for example, Zigbee provides whole-home wireless coverage with its mesh capabilities and makes it possible to control devices from outside the home via a gateway. When Bluetooth LE is introduced, a smartphone can be used for direct local control and location awareness can be added.

Sub-GHz wireless technologies are ideal for smart metering applications since they propagate over wide areas. By adding simultaneous sub-GHz and Bluetooth communication to metering IoT devices, technicians can utilize mobile apps for local setup, information gathering, and maintenance.

In retail or commercial settings, there is a desire to make use of technologies such as Bluetooth beacons to provide location-based advertisements, track assets, and develop heat maps to track foot traffic. By integrating Bluetooth beacons into connected infrastructure such as lighting, large-scale coverage areas can be created. Instead of having to deploy both connected lights and beacons, a light or luminaire can serve as the means to deploy Bluetooth beacons. This provides a more cost-effective avenue to enable location-based services.

What is Multiprotocol Technology?

Many connected devices can improve consumer experience and enhance functionality by supporting multiple wireless connectivity options. We are used to our smartphones supporting Bluetooth, Wi-Fi, and other connectivity options to provide streaming media as well as connectivity to headphones and smart watches. The power, size, and cost requirements for many IoT systems has traditionally made supporting multiple protocols challenging. Dynamic multiprotocol wireless connectivity provides a viable means to simultaneously support multiple wireless protocols on a single chip by using a time-slicing mechanism to share a radio between protocols, reducing wireless system cost and simplifying system design.

What are the benefits of supporting multiple protocols?

Here's a brief look at the different types of multiprotocol connectivity and their benefits.

Programmable Multiprotocol

Programmable multiprotocol support entails having a chipset that, when programmed with the right software stack, can run any number of wireless protocols. Being able to program a chip in production to support BLE, Zigbee, Thread or a proprietary protocol means you can streamline your hardware design and quickly address different markets. A chip platform that supports multiple protocols via different software images is a fundamental prerequisite for all other multiprotocol use cases.

Switched Multiprotocol

Switched Multiprotocol involves having two separate possible modes running on one chip. Each mode from a protocol and stack point of view is separate from each other. To swap protocols, you have two options: 1) Bootload the firmware image you want that contains the other protocol stack, do the communicating, and then bootload back to the other image, or 2) Have one image that has two modes to completely enable or disable each protocol.One example of this is a connected home device (like a door or window sensor) that only needs Bluetooth to be commissioned to join the network, and then will communicate via Zigbee for a vast majority of its life. To do this, you will ship the part with Bluetooth software programmed or enabled, interact with the user/installer via a phone, and then disable Bluetooth, enable Zigbee and join the Zigbee network. Then, typically the only way to go back to Bluetooth is via a user interrupt, like a button, or to reach out to the node via Zigbee to tell it to swap back to Bluetooth because the device cannot simultaneously remain on the mesh network and hold on to its Bluetooth connection. The time between swapping is very long – in the hundreds of milliseconds for Bluetooth and even longer for Bluetooth mesh.

Switched multiprotocol enables your connected device to change which wireless protocol is being used by bootloading a new firmware image when the device is already deployed in the field. Consumer experience of settting up or commissioning your product can be greatly improved by making use of smartphone connectivity to swtich between BLE securely onto Zigbee, Thread and other wireless networks. With the addition of over-the-air (OTA) updates, devices can also be updated in the field to evolve to changing market needs.

Dynamic Multiprotocol

Dynamic Multiprotocol is more fluid and flexible in its ability to swap and can more quickly hop between the two protocols. With dynamic multiprotocol, you do not shutdown or de-initialize the entire protocol stack; instead, you simply keep both running but swap who is using the physical radio, drastically reducing the time to switch. You are sharing the lowest level dependencies between the two protocols, which is typically the radio (this is represented as the bottom brick in the wall in the image below). By being able to swap faster, it allows Bluetooth Low Energy (BLE) connections to remain active, and at the same time remain on the Zigbee/Thread network, by ensuring you remain in the timing windows for each of the protocols as not to drop connection or be removed from the network. This allows the node to respond to either a command via Zigbee/Thread or Bluetooth, which means a user on the phone can control the node and the main network.A good example of a dynamic multiprotocol application is a door lock where you want the user to be able to lock/unlock to door via Bluetooth on their phone, as well as use sensors, time schedule, or cloud command via Zigbee.

Ultimately, any multiprotocol solution must address the possibility of simultaneously running multiple wireless protocols together on one chip, using a time-slicing mechanism to share the radio. This approach opens up even more use cases, especially when combining BLE with other wireless protocols. The simplest of these use cases involves the periodic use of Bluetooth beacons in retail environments from a device that normally operates on Zigbee, Thread or a sub-GHz wireless protocol.

Multiradio Multiprotocol

Dedicated operation of multiple protocols without any trade-offs, especially where different radio frequencies are used by different protocols, requires two radios. There is a lot of value in an application and networking stack that can operate across two radios that perhaps even utilize two completely different frequency ranges. One example is smart metering in Great Britain, where the government will deploy dual PHY Zigbee communications hubs in 30 million households and businesses by 2020. This effort is to enable a Home Area Network that contains both 2.4 GHz Zigbee devices and sub-GHz Zigbee devices (operating in the 868 MHz band), maintained on the same logical PAN with the communications hub routing traffic between devices on different radio frequencies.

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