Abstract
The use of massive multiple input multiple output (MIMO) has been considered as a key enabler to achieve the 5G requirements [1]. With the large array of antennas, the beamformers’ uses have become very attractive, specially when the energy is concentrated in a specific direction. However, implementing large arrays becomes prohibitive since the digital-analog converters (DAC) are power hungry devices connected to every radio frequency (RF) chain. So to deal with this bottleneck, the number of RF chains is reduced by using the hybrid beamforming (HB) solution whose implementation enables us to use fewer RF chains than the digital solution while maintaining a high number of antennas. In this work, we propose to extend a diversity-multiplexing transmission scheme called as G2+1+1 for massive MIMO systems in millimeter wave (mmWave) channel. To implement such scheme, we design a Hybrid Beamforming at the base station and a nonlinear decoder at the receiver. Compared with the traditional G2+1+1, our transmission scheme combines diversity, multiplexing and array gains into one unique device. We show in our simulations that our scheme outperforms in terms of bit-error rate (BER) other solutions that only exploit massive MIMO multiplexing gain. Such results show that the proposed solution is very attractive to increase the system reliability and provides enhanced robustness in low and high SNR scenarios.
Highlights
T HE data rate consumption in mobile communication systems is growing exponentially, and fifth generation (5G) systems need to provide technical solutions to follow this growth
The transmission is done by means of hybrid beamforming solution, so the large array gain can be used to steer the signal into a specific direction
To compare the proposed transmission scheme with different receiver solutions, we evaluated them in terms of bit-error rate (BER) assuming a QPSK modulation
Summary
T HE data rate consumption in mobile communication systems is growing exponentially, and fifth generation (5G) systems need to provide technical solutions to follow this growth. The converters are power hungry devices connected to every RF chain, so their power consumption in implementing large arrays becomes prohibitive To deal with this bottleneck, the number of RF chains is reduced by using some hybrid beamforming (HB) solution composing analog and digital filters whose implementation enables us to user fewer RF chains than the full digital solution while maintaining a high number of antennas. The results obtained in our work, show a system reliability improvement specially in low signal-to-noise ratio (SNR) and low angular spread scenarios, such as millimeter wave channels [17] Another advantage of this method is the design of the HB which is based on the partial knowledge of the channel.
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