Six Good Reasons to Use Multiradio Modules

Tim Bonnett
Director
Internet of Things wireless protocols
The number of wireless standards available for the Internet of Things, IoT, means that multi-radio interfaces will be needed for many applications.

Virtually every element in the IoT needs wireless capability; from the end- node through gateways to the databases in the cloud. In most cases you are under pressure to keep costs and board space as low as possible, and you probably have even more pressures to bring the product to market quickly.

An increasing need is for multiple wireless capability, for example when Bluetooth is used to discover another device and WiFi takes over to provide greater bandwidth for data exchange. Another widely used application is a gateway, which communicates with node points through Bluetooth, or another low energy protocol, and then uses WiFi or other wider bandwidth to communicate upstream.

Implementing radio is never simple; implementing multiple radios can be even more complex. And given the large number of wireless protocols that are now in regular use, including Bluetooth, Bluetooth low energy, WiFi at different frequencies, FM radio, NFC (Near Field Communication) satellite navigation and others, all providing facilities that meet specific market and application needs, the task facing a product designer can appear daunting. Some engineers might fancy taking on the design of a discrete wireless solution. Tempting as it might be acquiring the practical knowledge of wireless design, keeping up to date with wireless protocols and legislation is extremely tedious and will take years.  However, implementing your wireless design requirements using a multiradio module can simplify things greatly.

Let's look at some of the problems and how a multiradio module can help.

Design time: A radio chip is not just a stand-alone add-on to a circuit; it requires support components, such as crystals, oscillators, and an antenna, with its own matching components. Integrating these is time consuming. Adding a second radio chip is equally time consuming, and brings extra effort in avoiding signal interference.

A multiradio module is fully integrated with a well-defined interface to the rest of your circuit.

Board space: All those components take up board space. A well designed multiradio will optimise the components, may have multiple levels, and have either a single antenna output, or one or more internal antennas, all combining to give a very small board footprint.

Wireless co-existence: When you have two or more radios in close proximity, there can be problems of signal interference: resolving these problems can be difficult and time consuming. A multiradio module will have had these problems resolved for you.

Type approval: Depending on the frequency being used, radio transmitters often have to be given type approval before they can be used in a particular geographical market. This is time consuming and expensive. If you use a multiradio module the module developer will have already undertaken this task.

Multiple variants: Often you would like variants of the same basic design to provide additional features or to meet different market needs. A single device might be offered as Bluetooth only, WiFi only or both. This could be served with a single board with a single Bluetooth/WiFi multiradio module and activating only those radio services you need. With a single design and a single board in stock, this approach would be faster and less expensive than three different boards.

In addition to the benefits listed above to adopting a modular approach there are a number of other considerations that engineering management need to consider. These include equipping a design lab with specialist, and expensive, RF test equipment and potentially recruiting experienced wireless engineers into the team. Whether permanent and contract, it is another set of costs to factor into the end-design.

Multiradio modules may not be a universal panacea, but they offer an efficient route to building products for the Internet of Things. 

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