A novel two-dimensional (2-D) beamsteering transmitarray inspired on frequency selective surfaces is proposed in this paper. Individual phase range is applied to each transmitarray element and thus enabling the steering of the main lobe of an original antenna pattern in both elevation and azimuth planes (2-D-beamsteering). This has been demonstrated on a 5 × 5 unit-cell stacked structure, loaded with surface mount capacitors, coupled to the aperture of a standard gain horn antenna. Additionally, a complete parametric study based on electromagnetic (EM) simulations using CST Microwave Studio is presented to evaluate and characterize unit-cell parameters and the behavior of the array with various numbers of stacked layers and separation distances. Antenna beamsteering with ranges up to Az = 25° and El = 25° are achieved by means of EM simulations and validated against experimental results performed on a physical prototype at 5.3 GHz. The comparisons yield positive results and clearly demonstrate the potential and limitations of using such structures for beamsteering purposes.

This paper reports on a complete end-to-end 5G mmWave testbed fully reconfigurable based on a FPGA architecture. The proposed system is composed of a baseband/low-IF processing unit, and a mmWave RF front-end at both TX/RX ends. In particular, the baseband unit design is based on a typical agile digital IF architecture, enabling on-the-fly modulations up to 256-QAM. The real-time 5G mmWave testbed, herein presented, adopts OFDM as the transmission scheme waveform, which was assessed OTA by considering the key performance indicators, namely EVM and BER. A detailed overview of system architecture is addressed together with the hardware considerations taken into account for the mmWave testbed development. Following this, it is demonstrated that the proposed testbed enables real-time multi-stream transmissions of UHD video content captured by nine individual cameras, which is in fact one of the killing applications for 5G.

This study presents a frequency spreading filter bank multi‐carrier (FS‐FBMC) waveform as a potential candidate for the fifth generation (5G) network applications at millimetre‐waves (mmWaves). The proposed model is developed based on the orthogonal frequency division multiplexing (OFDM) waveform standardised by IEEE 802.15.3c for 60 GHz high data‐rate applications. The effects of non‐linearities of power amplifiers (PAs) at 60 GHz for both OFDM and FS‐FBMC are presented and compared using a realistic PA model. In particular, the sensitivity of both transmission schemes to the non‐linear effects is investigated and its impact on the performance degradation in terms of output‐power‐backoff, is characterised over typical indoor line‐of‐sight, kiosk and residential, 60 GHz IEEE channel models. The assessment metrics considered are bit error rate and out‐of‐band emissions. This study concludes radio access schemes for future communication generations, i.e. 5G may employ OFDM for up‐link and FS‐FBMC for down‐link due to the sensitivity to PA non‐linearities of both waveforms.

In this paper, the real-time over-the-air multi-gigabit wideband wireless orthogonal frequency division multiplexing (OFDM) system performance, using two distinct radio frequency (RF) front-ends designed for the millimetre frequency band (mmWave), is evaluated. A thorough comparative analysis between 60-GHz cutting-edge commercial off-the-shelf and reference RF front-ends, taking into account their intrinsic RF impairments and their impact on the overall system performance degradation, is presented. With this, it is possible to verify whether system on chip technology for RF circuits is ready for 5G systems. Due to the large available bandwidth, the mmWave band is very attractive for future 5G wireless communication systems, which might provide transmission data rates over 10 Gb/s and network latency below 1 ms. However, non-linearities of RF front-ends, at these frequencies, severely affect the performance of transmission schemes. In fact, this is the main cause for performance degradation on OFDM systems. It causes significant limitation on both maximum spectral efficiency and data rate of the wireless communication link. Therefore, the OFDM performance degradation due to the non-linearities from both analogue stages of upconversion/downconversion is evaluated considering important key performance indicators for quality of service in digital communications considering 4-, 16-, 64- and 256-quadrature amplitude modulation. Furthermore, based on the results obtained from appropriate RF measurements, a practical EVM link budget formulation for mmWave systems, which takes into account both PA and PN impairment effects, is proposed.

This paper presents an implementation of the IEEE 802.15.3c standard, in Simulink, for high data-rate applications. The recent standard IEEE 802.15.3c provides the implementation of such wireless communication system using the 60GHz frequency band. OFDM and SC-FDE are the two transmission schemes adopted by the standard. Performance of these technologies at mm-wave signals are severely affected by nonlinearity of the RF front-ends. This paper presents the impact of RF impairments for each transmission scheme along with comparative analysis, in terms of BER and PSNR.