Proposal Title: Reconfigurable Band-Pass Sampling Receivers for Software-Defined Radio Applications. Institution: University of California-Davis The last few decades have seen tremendous progress in the development of wireless communication technologies. Wireless technologies are tightly woven into every facet of today's society and have significantly contributed to the advancement of human civilization. Future wireless systems are expected to have even more functionality, longer battery life, smaller size and more importantly, lower cost. At the same time, a proliferation of vastly different wireless standards, devices, and systems has continued to challenge us to make better use of the already congested radio spectrum. One example is the 4G cellular networks, which have been allocated more than 40 different bands worldwide, causing significant implementation problems for cellular infrastructure providers and mobile handset manufacturers. To overcome these challenges, concepts such as software defined radios and cognitive radios have been proposed. In these systems, both software and hardware (analog and radio frequency front-end circuits) can be reconfigurable adaptively to make the most efficient use of the available spectrum. Although much research has been done in this area, making truly reconfigurable radio front-end circuit remains a challenge. In this research, we propose a band-pass sampling receiver architecture that is reconfigurable in terms of operating frequency, bandwidth, and signal waveforms. The proposed research will have a transformative impact on future wireless communication systems. The highly reconfigurable wireless receivers made available through this research will enable not only highly versatile mobile systems but also a significantly more economical and environmentally friendly telecommunication infrastructure. Such infrastructure and systems will result in more efficient utilization of and public access to the radio spectrum.
In contrast to a low-pass sampling receiver, the proposed receiver samples at a much lower frequency with respect to the center frequency of the signal. The analog-to-digital converter (ADC) in the band-pass sampling radio therefore operates at a much lower bandwidth, resulting in a significant reduction in power consumption. The I/Q separation and baseband processing (channel filtering, base-band AGC, etc) can be carried out entirely in the digital domain. This will improve flexibility in terms of adapting to different waveforms and wireless standards. The use of high-Q tunable RF band-pass filters ensures that minimum distortion is introduced by out of band interferers. Compared with existing solutions, the proposed architecture pushes digitization closer to the antenna as possible without having to sacrifice the dynamic range. The proposed receiver has the potential to significantly increase the utilization of the ever more crowded radio frequency spectrum.
The outcome of this research will be widely disseminated through academic and trade journals/conferences and the PIs' research group websites. The PIs plan to establish a summer outreach program on wireless technology to promote interests in STEM subjects, engineering in particular for high-school students and teachers. The outcome of the research will also be integrated into the graduate and undergraduate courses the PIs have developed. In addition, the PIs plan to engage undergraduate students in research to promote their interest in pursuing advanced degrees in engineering.
