Developing the First mmWave Fully-Connected Hybrid Beamformer With a Large Antenna Array

Abstract

Millimeter wave (mmWave) systems with effective beamforming capability play a key role in fulfilling the high data-rate demands of current and future wireless technologies. Hybrid analog-todigital beamformers have been identified as a cost-effective and energy-efficient solution towards deploying such systems. Most of the existing hybrid beamforming architectures rely on a subconnected phase shifter network with a large number of antennas. Such approaches, however, cannot fully exploit the advantages of large arrays. On the other hand, the current fully-connected beamformers accommodate only a small number of antennas, which substantially limits their beamforming capabilities. In this paper, we present a mmWave hybrid beamformer testbed with a fully-connected network of phase shifters and adjustable attenuators and a large number of antenna elements. To our knowledge, this is the first platform that connects two RF inputs from the baseband to a 16× 8 antenna array, and it operates at 26 GHz with a 2 GHz bandwidth. It provides a wide scanning range of 60 • , and the flexibility to control both the phase and the amplitude of the signals between each of the RF chains and antennas. This beamforming platform can be used in both short and long-range communications with linear equivalent isotropically radiated power (EIRP) variation between 10 dBm and 60 dBm. In this paper, we present the design, calibration procedures and evaluations of such a complex system as well as discussions on the critical factors to consider for their practical implementation. INDEX TERMS Millimeter wave, Multiple-input multiple-output, fully-connected hybrid beamforming, phased array antenna, testbed.

Reconfigurable Intelligent Surface (RIS) in the Sub-6 GHz Band: Design, Implementation, and Real-World Demonstration

“…It must be noted that the RIS is conceptually different from traditional beamformers [28] in several ways. The most distinguished one is that there is no RF-chain like it is applied in phased arrays [29]. Therefore, the structure is completely on its own in terms of aiming the reflected wave vectors.…”

The Role of Millimeter-Wave Technologies in 5G/6G Wireless Communications

“…4(c). In [44], the authors presented a hybrid beamformer consisting of two RF channels connecting to the baseband and a 128-element antenna array [see Fig. 7].…”

Review and comparison of different limited scan phased array antenna architectures

“…The HBF topology is reported in the literature to combine the low cost (low power consumption) of analog beamforming architecture with the multibeam generation and digital processing capability of DBF architecture to implement a low-cost multi-input multi-output multiuser (MIMO-MU) wireless communication system. 43 In an HBF system, a smaller number of RF chains (compared to DBF) are connected to a larger number of antenna elements which reduces the hardware complexity. And, moreover, the bulk of the spatial signal processing is done in the RF domain in order to reduce power consumption.…”