Shining a Spotlight on Software Defined Radio

NXP has been working with community driven efforts to support a new Software Defined Radio (SDR) platform that allows both industry and academia to bring new products and innovations to the world. The ultimate goal of this initiative is to make development hardware affordable for everyone and easier to use by making it software-centric.

What is the importance of the SDR platform?

The entry barrier to development of new hardware and software can be a struggle if you don't have "large company" resources or are not well-connected in the industry to make up for this. One of the reasons for technological progress over time is that hardware complexity keeps increasing. For example, designing and building a PCB is a lot more complex these days than a couple of decades ago. On top of this comes software complexity. Operating system, driver and application complexity all are increasing beyond what a single individual can manage.

So, what is the industry doing to fix this? The answer is typically reference design kits and single board computers. As an example, see the microcontroller space where MCX microcontrollers are enabled with FRDM Development Platform kits that allow partners to quickly come up to speed.

This is a great concept but rarely extended into an area as complex and "heterogeneous" as the telecommunications space where analog, digital, signal processing, radio frequency and traditional compute all blend into a single hardware/software product.

This is the challenge that the LA9310 Software Defined Radio (SDR) product tries to address. We're not sure whether we can claim a "world's first" here but it's certainly innovative in providing an FPGA-less (and thus easier to code) SDR platform at an extremely aggressive price-point.

Read the interview with Harsha Master (Principal System Architect, CTO office) and Wim Rouwet (Senior Principal Engineer, Secure Connected Edge) to learn more about this exciting project:

Q: What sets this project apart from the rest?

Harsha: It's the first of many - cost, size, features, flexibility, reconfigurability and more. Popular cost-effective SDR Modems on the market are FPGA based and feature-specific with fixed applications. NXP Long Term Innovation (LTI) SDR Development Platform uses a highly efficient programmable baseband processor LA9310.

On the market, SDR modems of the same capability are roughly 4-5 times more expensive, and better ones are even 20 times expensive. For example, this NXP LTI SDR board is about 250 USD, similar ones on the market are about 2500 USD.

Traditional cost reductions are due to reduced features, reduced speed and computational power, and fixed configuration. What is envisioned in NXP's LTI SDR board is cost and a wide range of applications and features.

The NXP LTI SDR main board is a fixed layout with baseband processor LA9310 and host processor i.MX 8M Plus to make the system as stable as possible. Daughter boards can be pre-made, custom-built by the developer or chosen from third parties or vendors.

Wim: These daughter boards can either pin out analog (baseband IO), implement wireline or wireless communication protocols or even functions like digital oscilloscope or Vector Signal Analyzer. Mix and match at its best!

From the software side, this project supports multiple open source initiatives. For example, look at the 5G world where we from NXP are putting quite a lot of our focus.

Here, stacks from the likes of OpenAirInterface, srsRAN, open5GS or open5gc apply. Or, 3rd party commercial vendors of course. Vicinity Wireless from Bristol/UK developed a 5G UE on this platform.

Of course, we support NXP internal development teams as well as startups and academia on this platform.

Q: Please tell us a little more about the different technologies behind this.

Harsha: LA9310 is NXP's most efficient, low-power baseband processor. It is also a popular entry-level baseband processor, cheaper in cost, and does not have complex export control restrictions. Unlike FPGA-based systems, NXP LA9310 is comparatively faster, compact and low power, yet flexible with programmable capabilities. Developers can use it as a modem, signal generator, or signal analyzer by rightly selecting plug and play RF modules.

i.MX 8M Plus is a very popular NXP MPU with unique capabilities, including four core processors, a TSN endpoint and hardware accelerators for AI/ML, camera/video and IoT, to name a few applications. i.MX processors are widely used in Automotive, Industrial, Robotics and Medical domains. In LTI SDR, it is used as a central control processor and runs required software stacks. For example, the entire 5G Layer 2/3 will run on i.MX 8M Plus.

SN220 is one of the proven combo NFC-eUICC-Secure Element solution in the mobile market. It interfaces uniquely in the system, enabling developers to use it as a "real modem" without using a plastic SIM card but with an embedded SIM. Developers can further use their imagination to use them in many combinations.

Q: So, what does it take to start such a project?

Harsha: This is really a case of "better together", both inside NXP across groups and outside with the larger ecosystem. It goes back a bit to what we talked about at the beginning with enablement typically being done on a per-product basis and best-in-class for the simpler products. At the same time, we see that the software enablement and support for typical large customers as done by NXP is not the same as what start-ups, academia and open source communities want. On top of all of this, we need to achieve an aggressive price point.

Wim: So, to achieve all of this, we decided pretty early on with an external partner initiative called RFNM who are much more in tune with the ecosystem needs. Sure, there's some NXP expertise ongoing "behind the scenes" but it is amazing to see what a community can do - way more creative application thinking than we could come up with ourselves. What has been helpful is the push from the community to make the platform open: BSPs, drivers et cetera are already NXP published/supported open source and we're trying to get more "out there".

Q: Let's ask RFNM what their view on this is.

Davide Cavion (RFNM): As someone that always dreamed of building an SDR and the ecosystem around it, the LA9310 was a godsend. Wim already touched on the lack of an onboard FPGA, but there is another important difference: the LA9310 comes with an analog, I/Q baseband interface. Unlike other products on the market, that use a chip integrating frontend, mixer and ADC, this lets us split the signal path between mixer and ADC on a board to board mezzanine connectors. If this sounds confusing, let me just jump to the conclusion: we only need to develop a motherboard once, taking care of all of the software and digital side, and customers can very easily develop daughterboards starting from a simple Altium template.

Q: Are there any tie-ins with industry buzzwords like 5G advanced, 6G and AI/ML?

Wim: As you would expect, within NXP we are working on all of these topics. But we're also seeing that a lot of the underlying research is very open in nature. So, we're enabling academia and startups with these boards so that they can start getting practical experience with new waveforms that are enabled by the programmable nature of the platform, or with AI/ML as included in the i.MX 8M Plus processor. There are some obvious limitations to what a low-cost development board can provide in terms of RF bandwidth, but then again, scaling up is often a more mechanical exercise as compared to inventing something fundamentally new. On top of this, if you take the view that 6G will likely be more open, software-defined and ad-hoc in nature and this type of platform being exactly what the industry will be looking for in the future. So yeah, we're pretty confident this SDR will be a part of a 6G future.

Q: When can users expect to get their hands on this?

Harsha: Now! Late 2023 was the time in which software was done, and hardware and software were validated to work. Boards have been shipped during early 2024 and software has been evolving ever since. You can order the platform directly via the RFNM website .

Q: What's next?

Wim: Well, there's a lot of work to be done still. The first batch of boards is built with the second batch hopefully opening up soon. Better get yourself signed up quickly if you want one. What we are seeing from our side is a bunch of new customer engagements based on this project. All these customers need to be supported to build their projects, demonstrate, optimize and commercialize them. That all takes time and effort that we are going through right now. You should be seeing the silicon on that SDR board making its way into commercial products in the next year or so.

Harsha: At the same time, we're looking at whether we can build a "big brother" of this system. More bandwidth, more compute, and so on. This would give a scalability to the platform that is missing right now. Ideally, this will also be "crowdfunded" and at the same time backed by NXP because it worked out well this time.

Authors

Special thanks to Francois Massot-Pellet and Fabian Mackenthun.

Project is supported by NXP's Long Term Innovation and executed under Industrial Innovation Board.