Percorrer por autor "Duarte, Luís"
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- All-digital reconfigurable STDCC radar baseband implementation in FPGAPublication . Duarte, Luís; Ribeiro, Carlos; Alves, Luís N.; Caldeirinha, Rafael F. S.This paper reports the architecture of an all-digital Swept Time-Delay Cross-Correlator (STDCC) baseband. Until recently, the sliding correlator technique has been mainly em-ployed for sounding the radio propagation channel. However, recent benchmarks have shown promising results in target detection context when compared to commercially available solutions. STDCC takes advantage of the sliding correlation properties of Pseudo-Noise (PN) sequences. Therefore, this paper presents the baseband generation for this new radar technique with on-the-fly sequence tuning using a Field-Programmable Gate Array (FPGA). The reconfigurable STDCC radar baseband generates both PN sequences digitally and requires a low-cost ADC to acquire the time dilated result. At the end, the proposed architecture is evaluated regarding resource usage efficiency and then the radar performance will be discussed in terms of the all-digital PN sequence spectrum and the real-time slide correlation. Our analysis confirmed a strong correlation between both sequence length and sampling frequency with radar detectable distance.
- Multi-Gigabit/s OFDM real-time based transceiver engine for emerging 5G MIMO systemsPublication . Ribeiro, Carlos; Gomes, Rodolfo; Duarte, Luís; Hammoudeh, Akram; Caldeirinha, Rafael F. S.This paper presents a highly scalable multi-Gigabit/s Real-Time (RT) Wideband (WB) Orthogonal Frequency Division Multiplexing (OFDM) processing chain for 5G applications. It is aimed to significantly reduce the Hardware (HW) footprint of Multiple Input Multiple Output (MIMO) systems. In this context, implementation complexity results for MIMO configurations of 2 × 2, 4 × 4 and 8 × 8, enabled at sampling rates of 245.76, 122.88, 61.44 and 30.72 MHz, respectively, are compared with the ones from conventional MIMO architectures. For example, for a 8 × 8 MIMO–OFDM configuration implementation, savings of up to 87% are achieved when compared with conventional design methods, in terms of DSP48E1 slices. Moreover, in a Xilinx Virtex 7 XC7VX485T, it is shown that a second processing branch might be implemented, leading to a 5 Gbps (using 1024 Quadrature Amplitude Modulation (QAM)) Single-Input Single-Output (SISO) link or a 16 × 16 MIMO configuration. Finally, in order to validate the proposed architecture, the impact of its inclusion on a complete Field Programmable Gate Array (FPGA) 8 × 8 OFDM system, at LTE's highest sampling rate of 30.72 MHz, is evaluated. Subsequently, it is demonstrated that this does not affect the performance of OFDM, even in the presence of Carrier Frequency Offset (CFO).
- Reconfigurable millimetre-wave RF front-end for radar and 5G applicationsPublication . Duarte, Luís; Reis, João R.; Leonor, Nuno; Ribeiro, Carlos; Alves, Luís N.; Caldeirinha, Rafael F. S.This paper proposes a reconfigurable RF architecture to cope with radar applications in autonomous driving vehicles and the next generation of communications (5G). A radio front-end architecture operating at frequencies between 24 and 27.5 GHz to deliver a small form-factor design that could easily be changed and ease future improvements, has been developed. Based on X-microwave ecosystem, a fully reconfigurable mmWave RF front-end has been designed and experimentally characterised. Due to the high modularity of the proposed front-end architecture, each mmWave RF component is tested and characterised in the frequency range of 24-27 GHz, allowing the final prototype to be used in future radar and communication systems. Results for the proposed architecture are presented at the component level, and, then with transmitter and receiver in back-to-back configuration. End-to-end testing and performance analysis clearly show the X-Microwave based solutions performance and the proper operation of the designed front-end in the up-/down-conversion of the baseband signal.