The next generation of wireless communication devices must achieve Gigabit data rates and low power consumption by making more efficient use of the radio-frequency spectrum and taking advantage of device interoperability. To meet these requirements, the development of cognitive radio devices will be far more complex than that of their predecessors. Large, interdisciplinary development teams are required to cover areas such as analog RF hardware, digital hardware design, digital signal processing and system architecture. With the research team selected for this project we believe to have put together all the expertise required to face the design challenges of the radios of the future.
The challenges of the future of radio communications have a twofold evolution, being one the low power consumption and, another, the adaptability and intelligent use of the available resources. In that this sense specially designed radios should be used to simultaneously reduce power consumption, and adapt to the environment in a smart and efficient way, so that the radio will use the least amount of power it can to communicate.
Nevertheless adaptability and low power tend to pursue different goals. In this project the knowledge gathered from the team in past projects and collaborations will allow them to propose innovative solutions for achieving both goals with equivalent weights. This project will thus aim to the design of fully adaptable radio transceivers by using all digital transmitters and receivers for multi-carrier, multi-standard communications, which will imply spectrum sharing for energy efficiency, e.g., through spectrum aggregation, with high dynamic range and large bandwidth coverage.
This could be achieved with pioneering approaches based on higher order bandpass sampling receiver implementations for increasing the bandwidth and by extending the receiver linear behavior to maximize dynamic range, either by using newer front end implementations or by exploring nonlinear distortion compensation schemes. All the approaches proposed in this project will be validated in a laboratory environment, thus a close collaboration between analog front end design researchers, digital hardware designers and signal processing specialists is fundamental to achieve an integrated vision of these systems. But as above mentioned, another challenge with the new generation of wireless communication systems is power consumption, which imposes strong drawbacks to the evolution of this technology for mobile smart handsets. This issue will also have a special attention, in this project, by carefully studying the energy spending patterns of cognitive radio transceivers, by optimizing power efficiency and, also, by integrating energy harvesting and scavenging stages within the transceiver design, which is expected to significantly increase the energy efficiency of the complete transceiver.
All schemes proposed above should be integrated in a unified view of the low power cognitive radio approach, which imposes that knowledge on system architecture will also be included, by bringing specialists in wireless communication networks to the project team whilst exploring communication opportunities that include cooperative relaying and the use of contiguous and noncontiguous frequency bands.
In summary we can affirm that this 5 year project will contribute to the advance in the state of the art in the following topics:
1 – RF front end transceiver design
a) Increase Bandwidth and Dynamic Range of receivers
b) Design of agile and power efficient all-digital transmitters.
c) Energy Harvesting and Scavenging for Wireless C ommunications
d) Antennas with high bandwidth, adaptable and MIMO capabilities
2 – Signal Processing
a) Hybrid Filter Bank Designs
b) Spectrum Aggregation Implementations
c) PAPR studies and optimization
d) Behavioral Modeling Aspects for the analog components and hardware optimization
e) Distributed spectrum sensing elements
3 – System Design
a) Distributed wireless communications
b) MAC design and Common Radio Resource management for optimized spectrum and energy efficiency
The project team integrates most of the research groups working in this area in Portugal, spanning from Universidade de Aveiro, Instituto Superior de Engenharia de Lisboa, Universidade da Beira Interior (all integrated in research teams from Instituto de Telecomunicações) but also from INESC Porto and IEETA in Aveiro.
The team strongly believes that this project will continue to make advances in the state of the art on cognitive radio approaches and will have an impact in the future of radio transceiver design.
