Reader Forum: Adding 3G radio to embedded devices: Five steps to success

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Using 3G wireless technology in handsets enables popular multimedia features for consumers; the same 3G technology can pay huge dividends for embedded industrial applications.
The 3G benefits that enable popular consumer handset applications – greater bandwidth, faster speeds, and simultaneous voice and data transmission – can make a whole host of new features possible in industrial devices, such as handheld terminals, surveillance systems, autonomous robots, medical devices, kiosks and video billboards.
Is 3G worth the investment for your project? The most notable advance is speed. Under the third generation wireless standards, it’s possible to reach download speeds of 14.4 megabits per second and upload speeds up to 8 Mpbs. For industrial applications, that speed increase means it’s now possible to wirelessly stream high-quality video from surveillance systems or to kiosks or video billboards.
The other major change is the ability to send voice and data simultaneously over the same wireless connection. This advance can allow your field workers to talk on a data terminal to dispatchers while uploading data, or the ability to add video conferencing to a tourist kiosk.
Are these features you could use? The 3G technology offers so many options that there’s no “best” way to add it to your device. Here are five steps to help make your 3G project successful.
Step 1: Ask the right questions in the requirements phase
There are a few key questions you’ll need to consider during the requirements phase.
1. What cellular networks will be available for your device? Different radio technologies are supported in different areas of the world. For example, most North America cellular systems use CDMA, while GSM is the standard in much of Europe, Australia, Asia and Africa.
2. How many devices will you ship? The answer will largely determine the type of radio you should use.
An embedded radio chipset designed into your circuit board requires the most engineering, development and certification effort, but has a low per-unit cost. If you plan to ship more than 100,000 units, the sizeable upfront investment may be worth it.
For low-volume projects of less than 1,000 units, an air card or dongle radio is often a good choice. R&D and certification costs are minimal – in some cases, it’s practically plug-and-play – but individually these radios need the most space and cost the most.
For production rates of up to 20,000 to perhaps 100,000 units, embedded radio modules are ideal. The embedded module is an enclosed device with the certified radio chipset. Just add an antenna.
Do keep in mind that if you need to use the 3G radio for voice calls, an external radio is not a good choice – even for low-volume projects – due to the work you’ll need to do to route the voice paths onto external radios.
3. What is the lifespan of your device? Be aware that just because you don’t need the high-speed capability of 3G now, you may need it in the future. Consider the data plan cost over the entire life of the device.
Older technology (2G, 2.5G) may not maintain its cost advantage over the lifespan of the device if network operators offer incentives to move traffic onto the newer 3G infrastructure. Additionally, network operators may phase out older technologies.
Step 2: Understand certification testing up-front
To operate on a commercial network, a 3G radio must be certified by several organizations including the network operator. In short, the more embedded your radio, the more certification work you must do. With an air card or dongle, you may only have to work with your cellular network. With a fully embedded radio, you’ll also have to win government (i.e. Federal Communications Commission in the United States) and 3G standards certification.
Here are some tips for streamlining certification:
–Get your wireless carrier’s requirements as early as possible and design to those specifications.
–Work with a certification house to do advanced testing before you apply for certification.
–If the economics work out, consider using a pre-certified radio.
Step 3: Plan hardware changes
The size of your radio has huge implications on your hardware design. If you’re using a large radio, understand that you may need to make housing and electrical changes to incorporate it. Also, make sure that you have the necessary hardware interfaces available.
Choosing an antenna also requires careful consideration. A bad antenna choice or placement can void the capabilities of a high-performance radio. The antenna is often the cause of certification problems. Test early to uncover problems when modifications are less costly to make.
Step 4: Integrate software
You must also develop software that integrates the hardware into your system. If using a commercial operating system such as Windows Embedded CE, this typically involves modifying a radio software stack, integrating radio drivers and modifying the power management architecture to support the radio module.
Integrating the radio is not an isolated code addition. Numerous hooks are required. A USB 2.0 driver will need to be integrated with the USB controller on the embedded radio or mini-module. Voice and data pathways must be carefully programmed.
An option for streamlining software integration is to choose an embedded radio with pre-integrated, pre-tested software.
Step 5: Provisioning
To use your device on a 3G network, you will need to work with the network operator to provision the phone. You can either activate the device during production, installation or the first time that it is used.
For example, a vending machine technician could easily activate it when installing it on location. Handheld terminals and anything designed for resale should probably be provisioned during manufacturing.
Conclusion
Adding a 3G radio can open your device to advanced new features and capabilities, even in remote locations. By carefully considering your needs now and in the future, exercising careful attention to detail throughout the development process, and using pre-built components and software when appropriate, you can take advantage of its potential while minimizing development time, design complexity and expense.