This dissertation work was motivated by the desire to bring UWB technology to a wider range of uses, by lowering its hardware implementation costs while still offering a useful solution for fast IR-UWB system deployment in programmable logic, in particularly FPGAs.
Since the liberation of the UWB spectrum and the authorization of UWB communications by regulatory agencies, this technology has been thoroughly researched in the academic world but only few and expensive commercial solutions are available up to this day, generally only accessible to military, government or academic institutions.
In order to further contribute to a wider utilization of UWB communications, and reaping the benefits of centimetre level ranging capability and higher communication data-rates, UWB implementations on programmable logic can help to expand the use of UWB radios to hardware already commonly available. This is relevant as it allows IR-UWB prototyping in various types of applications scenarios, otherwise not possible with less practical solutions. The use of FPGAs also makes the architecture more versatile and portable when a system upgrade is demanded.
One of the main challenges for accomplishing the proposed goals was to deal with uncontrollable delays within an FPGA’s internal logic elements and ensuring that CTBV chains would offer more or less constant propagation delays for precise pulse generation and pulse detection. Ensuring this, in spite of having no control over the FPGA’s Place & Routing process with the IDE used, actually allowed the development of a more universal approach that does not require manual floor-planning with the current hardware. By using common Verilog primitives, in ways not usually recommended by HDL development guidelines, it was actually possible to average out inherent combinational logic delays when no sequential logic and clock controlled buffers are used.
There are, however, associated limitations with the current hardware implementation. For instance, performance is still somewhat limited when compared with ASIC UWB solutions. Despite these limitations, the CTBV IR-UWB architecture inspired in Professor Tor Sverre Lande’s works can demonstrate how even the less capable FPGAs can be used in various UWB use cases. The solution is also portable and can be further developed, integrated and deployed on more capable hardware to find its use in many applications of the modern day. It is a simple, low-cost and easily re-configurable IR-UWB baseband generator and detector architecture for a less complex next-generation IR-UWB system for the masses.
Summary of the Work Done
The main accomplishments and performed tasks for this dissertation work are briefly summarized in this section:
- Development an description of an adapted CTBV IR-UWB architecture suitable for being implemented in FPGAs and associated techniques for code generation and detection;
- Development of two IR-UWB applications for proof-of-concept scenarios: Ranging measurements and Transceiver operation, in order to demonstrate the validity of the proposed architecture;
- Implementation of the mentioned architecture in Verilog HDL and Matlab scripts for supporting the proof-of-concept demonstrations;
- Deployment of the proof-of-concept scenarios to an actual hardware implementation;
- Testing and performance characterization of the hardware implementation for the Ranging
and Transceiver configurations under multiple conditions.
UWB technology has an enormous potential number of use cases in the modern day, in applications that can benefit from high-resolution ranging and fast communications at high data-rates. Undetectable communication by common Narrowband receivers is another possibility for stealth or military agencies or even in privacy-sensitive communications, as shorter pulses spread the energy over a very large bandwidth.
Besides the Ranging and Transceiver applications demonstrated in this work, which can be used for transmission line fault mitigation and for digital communication purposes, there are many other possibilities. For instance, the deployment of automotive radar and collision avoidance systems can be based on UWB, leading to an even more safe driving. Others include low-power sensor networks for the IoT and industrial applications that require precise distance measurements. Additional applications and future works include:
- A true random number generators based on actual hardware, by letting the input pin of the
RX CTBV chain floating close to is threshold potential,VCCIO, and continuously sampling
the chain for random binary sequences of a desired length;
- The inclusion of fast communication interfaces, such as USB soft-cores, to explore the
possibility of faster data-rates between the system and the external control system;
- The utilization of video or audio signals as Transceiver payloads to evaluate the viability of
using the system for meeting tight timing requirements;
- The deployment of the architecture to a more capable hardware and reaching sub-nanosecond
measurement resolution and faster data-rates;
- A dissertation work focused on continuing the work done and porting the current hardware
implementation to the wireless domain, enabling radar measurements and IR-UWB wireless