The advancements in radar technology, particularly the development of 4D radar, have revolutionised various fields, including automotive safety, aviation, and weather monitoring. At the core of these sophisticated systems lies significant innovations in digital signal processing (DSP) and antenna design, both of which have been a central focus of Provizio R&D for the past number of years. In this post, we’ll explore the current challenges faced by 4D radar systems, and how Provizio technology pushes the bounds of what’s possible in the space.

What is 4D Radar?

4D radar is an evolution from traditional radar systems, adding the dimension of elevation to the existing coordinates of range, azimuth, and velocity. This additional data dimension allows for more precise tracking and identification of objects in three-dimensional space and their speed.

Key Components of 4D Radar Systems

1. Transmitter and Receiver Arrays: Modern 4D radar systems typically use phased array antennas, which consist of numerous small antenna elements. Each element can be controlled independently, allowing for electronic beam steering without moving the antenna mechanically.
2. Frequency Modulated Continuous Wave (FMCW) Technology: Many 4D radar systems utilise FMCW technology, where the radar signal’s frequency is varied over time. This allows for the simultaneous measurement of range and velocity.
3. Multiple Input Multiple Output (MIMO) Techniques: MIMO technology is used to improve the resolution and accuracy of a radar system. By transmitting multiple signals and receiving their echoes through multiple channels, MIMO enhances target detection capabilities and enables improved spatial and angular resolution.
4. Fast Fourier Transform (FFT): FFTs are employed to convert time-domain radar signals into the frequency domain. This transformation is essential for determining the range and velocity of targets.
5. Doppler Processing: By analysing the Doppler shift in the frequency of returned signals, the speed and direction of an object can be determined.
6. Angle of Arrival (AoA) Estimation: Sophisticated DSP algorithms estimate the AoA of radar signals, which provides information on the object’s azimuth (horizontal location) and elevation.

Challenges with Existing 4D Radar Technology

1. Computational Complexity: The high volume of data and the complexity of the algorithms require significant processing power.
2. Real-Time Processing Requirements: The requirement for real-time signal processing for applications like autonomous driving and collision avoidance is technically demanding. There is a constant need for faster and more efficient processing algorithms.
3. Antenna Design: The complexity of designing phased array antennas for 4D radar systems is significant. These antennas must accurately manage beam steering in three dimensions, which can be technically challenging and expensive.
4. Size and Integration: Incorporating 4D radar systems into smaller platforms, such as those required for mass market automotive or mixed mobility applications, can be constrained by the size and power requirements of the hardware.
5. Manufacturing Costs: The cost of producing sophisticated phased array antennas and other components of 4D radar systems can be high. This impacts the scalability and adoption rate in various industries.
6. Complex Algorithm Development: Developing algorithms that can effectively interpret the complex data from 4D radar systems is challenging. These algorithms must be robust, accurate, and able to differentiate between a wide range of target types.

Taking 4D to the Next Dimension

Key to 5D Perception® is our advancements in radar resolution and range. Digital radars in vehicles today generally have a single radar chip, with 3 transmit channels and 4 receive channels that allow them to deliver a virtual antenna array of 12 elements. In radar, the number of elements is like the pixel count for cameras and larger virtual apertures are preferred to improve resolution. Today’s radar has a typical detection range from 100m to 150m. These sensors enable the basic and dependable adaptive cruise control (ACC) and Automatic Emergency Breaking (AEB) on vehicles. However, to enable safe autonomy Provizio brought learning from advanced aerospace applications and developed a dedicated cost-effective solution for the automotive vehicle market.

Previous to Provizio our team built products that NASA described as “awesome” and the world’s leading autonomous driving group described as “the gold standard” in automotive Radar. That experience led us to envision a completely different, patent protected (7 at the time of writing), approach to software defined imaging radar.

MIMSO®

MIMSO^® (Multiple Input Multiple Sparse Output) is a software defined active antenna technique, which embeds proprietary surface-mount technology (SMT) integrated circuits (ICs) into a novel planar antenna design. This allows us to lower the receive path noise floor and discriminate more of the radar beam by essentially recycling parts of the radar beams that have traditionally been filtered. On the transmit path, our SMT ICs allow us to carry out instantaneous beam switching, which multiplies our transmit channels and further increases our resolution. Ultimately, MIMSO allows us to extract more than 30x the resolution from each physical radar channel.

SPTDMA™

Our proprietary software modulation technique, SPTDMA™, is a new form of multiplexing that enables unparalleled 6K resolution out to over 600m in all weather conditions, with the added benefit of protecting against interference from other sensors.

Industry Limitations

In radar systems, there are different modulation schemes that can be used to transmit and receive signals from multiple targets. One such scheme is Time Division Multiple Access (TDMA), where each transmitter transmits a signal on separate time slots. This allows the received signals from each transmitter to be easily separated with minimal computational overhead. However, using TDMA modulation comes at a cost of reduced maximum unambiguous velocity measurement, since the frequency at which measurements can be performed is limited by the time delay introduced by the allocation of time slots for each transmitter.

To address this issue, another modulation scheme called Doppler Division Multiple Access (DDMA) can be used. In this scheme, each transmitter transmits simultaneously (eliminating the time delay) and a series of algorithms are used to recover the velocity of a detected object by correctly matching each received signal to the transmitter that sent it. However, this approach is limited by challenges in accurately determining the velocity of targets and resolution limitations for objects that are closely spaced. Moreover, the addition of complex algorithms to match transmitter/receiver signals requires sophisticated signal processing that can lead to increased computational demand and pose challenges for real-time processing.

The Benefits of SPTDMA

Provizio’s patented SPTDMA (Slow Phase Time Division Multiple Access) solution combines TDMA and DDMA techniques by splitting multiple transmitters into smaller sub-arrays, with each sub-array transmitting simultaneously on an allocated time slot. In this way, while there is a limitation on maximum unambiguous velocity compared to a pure DDMA system, we can increase the number transmit channels to improve angular accuracy and range, while keeping computational complexity low enough to enable real-time, on-the-edge processing.

The Competition

The incumbent Tier 1 radar manufacturers are all developing 4D radar to enable Level 3 driving. They have very little differentiation and are almost all building forward facing 4D radars with 192 virtual antenna elements, delivered using 4x COTS radar chips. A big improvement, but nowhere near AV requirements.

There are also other competitors working to develop super-resolution radar. These solutions generally fall into one of two camps:

• Filled Array Radars: A brute force approach where more and more physical radar channels are added until you get to 1° angular resolution. Several companies have announced they are building radars with 2304 virtual elements by using 2304 physical radar channels. This has 2 major disadvantages:
  • Cost (12x channels = 12x cost).
  • Noise (Radar has a ‘cross-talk’ problem and the proximity of radar channels exacerbates it).
• Very Sparse MIMO Radars: The homeopathic approach where you dilute the number of radar channels using a very sparse array (some across the entire vehicle!) or by using AI neural nets (NN) to infer more resolution. The problem here becomes trust, can automakers trust these sensors not to miss detections due to over dilution in the array?

The Provizio Advantage

• MIMSO® can be applied with any Commercial off the Shelf (COTS) radar chips, which allows us to licence to multiple partners and applications to deliver high resolution perception at a significantly larger scale and lower cost than previously possible.
• MIMSO® allows us to deliver 3x more resolution and 2x the range of the most ambitious filled array approaches, but at 12x lower cost.
• Provizio delivers more than 30x the resolution and double the range of the incumbent Tier 1 sensors at a similar cost to the solutions they are employing today.
• Provizio’s 5D Perception® Radar integration costs are much lower than other sensors. The MIMSO® Radar cover (the radome), is made from low-cost polycarbonate plastic i.e. the same as the car bumper, so it can be seamlessly integrated in the vehicle body. They are super robust, and bugs, dust, weather and interference have negligible impact on performance. As a result, it is possible to have 5D Perception® radar integration which does not impact the vehicle aesthetics and still delivers 600m radar performance.

Conclusion

Provizio has invested significant resources in pushing the bounds of what’s possible with 4D radar hardware and software technology. With our patented MIMSO® and SPTDMA™ systems, Provizio offers finer resolution, faster processing speeds, and more accurate target detection and tracking, delivering compelling solutions to enable the transition to L3+ autonomy and the future of automotive safety.