Cat-NB1 and HaLow Wireless Links Powered by Tensilica Fusion F1

A generic Internet of Things (IoT) device consists of some sensors, some computations, and a wireless interface. (There are other types of designs but those are the basics.) IoT devices are characterized by requiring extremely long battery life, perhaps as long as the lifetime of the device. In turn, this means that sensors, computation, and the wireless communication must use very low power. This post is focused on the wireless interface. IoT devices do not need much bandwidth, and so the basic idea that any IoT wireless standard is to trade off the undemanding bandwidth requirements for lower power and lower cost.

There is a plethora of standards out there, more than can possibly all be successful in the long run. Some of the most significant include:

• Low-rate personal area wireless networks (802.15.4) with some protocol, such as Zigbee, on top
• Bluetooth, especially Bluetooth 5
• WiFi to a home router, in particular, 802.11ah, also known as HaLow
• Cellular, in particular, NB-IoT, also known as Cat-NB1
• and many more

This post takes a look at NB-IoT. With a lower-case 'n', the term covers most of these technologies, but NarrowBand IoT (with an upper-case 'N') or NB-IoT, is a specific standard being finalized as part of the 3GPP standard (currently on release 13). So it is part of the overall LTE roadmap. One of the attractions of NB-IoT is that the infrastructure already exists and it doesn't require the deployment of a new network of hubs or base stations.

The focus of NB-IoT is on low cost, long battery life and allowing over 200,000 connected devices per base station. It is designed to be deployed in three ways, either in spectrum allocated to cellular LTE, or in its own dedicated frequency band, or in the special case of re-deploying old GSM spectrum as it is freed up by the movement from obsolete standards. Large cellular companies, such as Verizon, are starting to test deployment at the moment. The bandwidth is limited to 100kbps. That's obviously low compared to a modern smartphone, but it's not that long ago that the state of the art for connecting to the internet were 56kpbs modems. (If you are nostalgic for the noise they used to make, be my guest).

I talked to Gerard Andrews, Cadence's product manager for the Tensilica Fusion F1 DSP. This core is the basis of the partnership announced today with CommSolid. You've probably never heard of CommSolid. They are a startup based in Dresden, Germany. In fact, they are the former Intel LTE team in Germany with a successful track record of LTE development over more than a decade. They already have over 30 engineers.

They have announced the CSN130. The block diagram is below. CommSolid is an IP company; they do not build their own chips. So this is an NB-IoT subsystem intended to be licensed and then to go on a chip with the implementation of the rest of the IoT device. It can be implemented in 65nm and in subsequent process nodes. The IP consists of a pre-certified hardware design and software stack for fast deployment.

Some features to note:

• There is a very small always-on domain (at the top) and the rest of the device can be powered down.
• The DSP core is the Fusion F1 and it handles all firmware layers and the RTOS.
• The DSP is extended using the Tensilica Instruction Extension (TIE) with additional custom instructions to optimize NB-IoT implementation.
• There is enough headroom in the processor to allow other functions, such as voice triggering, to be run as well as NB-IoT.
• There are AMBA interfaces, so it fits seamlessly into an ARM-based IoT device.

There is a full FPGA-based reference implementation with:

• Antenna, onboard and external
• SIM card holder
• Host interface
• Network interface
• Off-the-shelf radio chip
• Debug interface

Also, today, Cadence announced another relationship, this time with Methods2Business who have built a HaLow MAC IP using the same Cadence Tensilica Fusion F1 DSP. Methods2Business are based in the Netherlands with a design center in Serbia. The CEO is Marleen Boonen, who was at Philips Semiconductors (now NXP, soon to be Qualcomm) for many years and who I interacted with while at many EDA companies, including during my last tour of duty at Cadence.

HaLow is the more catchy marketing name for 802.11ah, which is a WiFi standard intended for connecting IoT devices to the cloud via a home WiFi router (obviously it has to be new enough to support HaLow). The focus of both this IP block and the HaLow standard, in general, is low power and low cost. There is enough processing headroom on the Fusion F1 to run more than just the 802.11ah firmware, but also other applications such as voice trigger, sensor fusion, and audio identification.

if you are going to Mobile World Congress in Barcelona, then we will be showing both these Fusion F1 DSP-based technologies on the Cadence booth. You can request a scheduled meeting here.