Beamforming Modulated Load Distortions in Advanced Transceiver Systems
Does building new adaptive algorithms excite you? Do implementing digital processing on real hardware interest you? You have a knack of playing with microwave devices and desire to sit in a RF lab? Building electronics is your hobby? If so, we have a challenge for you. Are you up for it?
Advancement in 5G faces steadily growing demand for variety of use cases for far higher number of users at the same time. This puts demand on utilizing spectral efficiency. One way to enhance this, is by using multiple antennas. Large scale advanced antenna systems comprising hundreds of antennas perform beamforming to enhance such utilization. Such integration avoids using bulky components such as isolators, between power amplifiers and antennas. However, such designs also become vulnerable to crosstalk due to mutual coupling between the antennas and related mismatch effects. These effects, together with nonlinear distortion at the Tx output create undesired radiation field properties.
This thesis will investigate technique for comprehensive analysis of nonlinear and dynamic characteristics of multi-antenna transmitters (Tx). The analysis is implemented by developing a dual input model of power amplifier (PA) which takes joint consideration of PA nonlinearity, antenna crosstalk and mismatch effects in multi-Tx system. With the ever-increasing Tx chains in modern radios, spatial multiplexing is due to increase higher. This along with beamforming, however, also introduces scope of coupling between Tx ends which are seen as loads at antenna ends. So, to study effects of multi antenna crosstalk on transmitter linearity in digital beamforming scenario an approach of active load modulation was developed and investigated for various dynamic conditions in one of the previous researches. This thesis work builds on the finding from such an experiment or results, bring out a realistic platform to confirm the results and further in consonance with the findings design an optimized solution for digital pre-distortion in active antenna systems.
Carryout literature research about the contemporary work done in this area.
Implementing digital processing of Tx chains on FPGA. Building synchronization for multi Tx implementation on multiple FPGAs.
Building the RF frontend layout for multi antenna transmitter with on board synced routing output to synthesizer.
Creating digital beamforming scenarios/algorithms and its implementation.
Building calibration for the built setup.
Modelling or analyzing models for nonlinear and non-causal system.
Studying and investigating the nonlinear distortion results from previous research work.
Analyzing the effects of mutual coupling or antenna crosstalk on transmitter linearity.
Investigating or building state of the art pre-distortion algorithm for such systems.
Optimization of Digital Pre-Distortion technique in relation to distortion/compensation regards to mutual coupling of advanced antenna system.
Required areas of interest:
We would like students with following areas of interest to take this challenge.
RTL Design, ASIC/FPGA hardware implementation, FPGA design flow
Learning, Optimization and adaptation algorithms, Statistical analysis algorithms
Good knowledge of Digital Signal Processing concepts
Understanding of microwave engineering concepts and knowledge of microwave devices.
Understanding of SDR, Radio Communication, Wireless communication, Cellular Network, LTE & NR
Experience on RF instrumentation would be advantage.
Understanding of Digital, Analog and Mixed Signal domain design
Transceiver knowledge, Knowledge in Analog Circuit design would be advantageous
Experience or exposer to layout design on any of the circuit design tools such as Cadence, Eagle etc.
Good programming skills
We would like to have students who desire to learn new things along with the ability to collaborate and work as a team for a research work. Students pursuing their major in one of these fields are encouraged to apply.
MSc in Electrical Engineering, Wireless Communication, Mathematics, Computer Science or similar.
Extent: 2 students. We would encourage two students to apply who could compliment most of the above-mentioned areas of interests between them.
Work Location: Lund
Preferred Starting Date: August/September
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Primary country and city: Sweden (SE) || || Lund || Stud&YP
Req ID: 336627