Wireless modules point the way for IoT connectivity
If there is one hardware feature that practically all embedded systems now have to have it is some form of network connectivity. For many devices, wireless connectivity is the smartest option. The wireless approach makes installation far easier, particularly with the arrival of features such as mesh networking that now form part of the Bluetooth 5 standard.
Wireless networks such as LoRaWAN make it possible to access devices from miles away at very low cost. Designed to transport small packets of data at rates up to 50kb/s, LoRaWAN requires very little power from the embedded device itself. This makes it highly suitable for sensor nodes, asset tracking and metering applications and avoids the complexity of using embedded subscriber identity modules (SIM) that are needed for cellular connectivity, which is the other main option for wide-area wireless networks.
For short-distance wireless networks, WiFi remains a highly effective option, particularly for systems that need high-bandwidth support, such as video security.
The issue that faces the IoT or embedded-systems designer is integrating wireless connectivity into the product. Different markets may call for certain wireless protocols to be used. For example, in the WAN environment, commercial considerations may force the use of cellular over LoRaWAN, or vice versa. Customers may want the option of using Bluetooth or WiFi depending on the specific location of each device and the availability of local hubs and routers. Addressing the possible choices with a custom design complicates what can already be a troublesome part of the design process.
However, each wireless interface adds complexity if the design is performed from scratch. One of the key issues with RF design lies in the interaction between components in the signal path, from the signal path down to the baseband interface. Tiny changes to the PCB layout and stack can result in dramatically different RF performance. The designer is also faced with the problems of creating reliable firmware for what, in the case of standards such as Bluetooth and WiFi, are now highly complex protocol stacks. Even when the design is finished, the design team has to perform stringent tests to demonstrate compliance with regional standards.A further wireless interface worth considering is Near Field Communication (NFC). This makes it easy for installers to provision and configure modules. Simply by touching an authorised device to the new module, important credentials can be downloaded and installed so that the unit can quickly establish itself on the core network.
The complexity of wireless design makes the option of using readymade and pre-tested modules increasingly attractive. A wireless module is much more than a prepackaged set of components. It is an investment in the competency of a team of RF specialists and their ability to create a design that will work across many environments.
A key aspect of effective wireless module design is that the interactions between antenna, package and front-end components are largely isolated to the module itself. To a large extent, all that is required to incorporate the module into an embedded system is to follow the integration guidelines. This results in far fewer design iterations. Furthermore, most wireless modules have already been tested and certified to comply with regional RF standards. That all translates into faster time to market: a vital consideration in today’s rapidly evolving IoT. And it lets the device designers focus on the added value they bring.
|Module||Discrete / on-board||Module benefit|
|RF design||Core competency of module vendor
heavy 1-time investment of module vendor
|Expertise required for layout,
signal routing, layer stack-up,
|Lower RF team requirements
Fewer board design iterations
|Size||Size optimised||Non-module will require larger
area on target PCB
|Saves board space|
|Procurement||1 component||Non-module will increase
procured BOM management
|Reduces operational costs|
|Assembly||1 component||Full BOM||Reduces production costs|
|Test||Module fully tested||individually tested end-product||Reduces test costs and
|Quality||Module are fully tested teams of RF specialists||
RF expertise and test flows
|Reduces test costs and
|Yield loss||Pre-yielded modules||Yield losses in production
Failure analysis and rework costs
|Reduces production costs|
A comparison of modules vs. discrete solutions
It is tempting to think discrete design saves cost. After all, having the components all mounted on a single PCB saves on materials. And the design team can optimise component combinations for the specific applications they have. They do not need to consider the potential for a wide variety of use cases. But such theoretical cost savings do not often translate into reality. The module manufacturer has the advantage of production scale, which helps keep prices down. And it is very easy to forget the impact of non-recurrent engineering costs, particularly if the design team needs to call on outsourced services to complete the project. Specialist equipment, such as antenna matching and tuning equipment can cost thousands of dollars: a significant outlay for projects that do not expect to ship in high volume.
Modules also make it possible to maintain a longer product lifetime with less need to monitor key components for obsolescence. Module manufacturers will often commit to form and function compatibility for their products. If a particular RF component is rendered obsolete, the module manufacturer will use other options that are readily available on the market and integrate them without changing the module’s footprint. Often, the use of modules will allow manufacturers to upgrade features such as range or power consumption without having to make any changes to their core design. And, if market requirements call for the adoption of a new wireless standard, a move to a multistandard module in the same form factor will allow it. Whatever the wireless interface you need, the module option will most often make the most sense.
Whether you’re developing a short or long-distance wireless network, we have a wide range of resources to support your design, and wireless modules from leading suppliers including Alps, Fujitsu, Murata, Panasonic, and Taiyo Yuden. Explore them below, or alternatively get in touch with us via Ask an Expert to discuss your requirements with one of our technical specialists.
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- Designing LoRa and Sigfox nodes with Murata’s dual-mode Open MCU LPWAN module
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