Mixerless RF Transceivers for Wireless Communication

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The explosive growth occurring in the past two decades in the wireless communication sector has, by association, seen a growth in communication technology and its applications. This new growth has been driving the need for an exponential increase in data rates. Given today's technology and current knowledge about wireless transmission, if data rates were to substantially increase, current wireless communication systems and techniques will not be able to handle the demand. To cope with this challenge, the increase in user bandwidths has been considered as a potential solution for future wireless infrastructure. In order to provide the required bandwidth in a highly used set of discontinuous frequency bands, advanced wireless communication systems are needed. These systems require multi-standard and carrier aggregation capabilities to be more ubiquitous, mobile, agile, and secure. This calls for the development of software-defined, reconfigurable, wideband and cognitive transceivers. Conventional transceiver radio frequency (RF) front-end architectures are analog-based and therefore are hard to reconfigure and are prone to noise, nonlinearity and hardware impairments. In addition, the use of switching-based mixers in frequency conversion generate a large amount of spurs and harmonics that need to be filtered out carefully using non-configurable, frequency limiting and bulky RF filters, which limit the agility and reconfigurability of these transceivers. A more compelling alternative is to move the design to digital domain and/or to avoid the use of mixers and filters in frequency conversion. The proposed research is part of a research program that aims at developing innovative reconfigurable RF transceivers for advanced communication systems that are able to operate in wideband and to be reconfigured at will. In this proposed research, innovative highly integrable, reconfigurable and wideband transmitter architectures suitable for multi-band and multi-standard applications will be investigated at two different levels: ***(i) New transmitter architectures will be developed. This architecture uses digitally controlled "mixerless" frequency up-conversion topologies. Without the use of analog RF filters, the proposed topology will be able to operate over wide frequency bands and therefore can be configured at will for different standards.***(ii) New models and algorithms for system behavioural modeling and digital predistortion will be investigated in order to mitigate the nonlinearity and analog imperfections in these topologies.***The proposed digitally controlled and linearized transmitter architectures are expected to have great potential of high integrability, reconfigurability and low cost, which make them an interesting solution for future radio systems and ubiquitous networks.**