Journal of Communications and Information Networks, Vol.4, No.3, Sep. 2019 Research paper
Hybrid Beamforming Design for Uplink
mmWave Systems with a Predefined
Low-Resolution Codebook
Chao Han, Jiaxing Wang, Jingchao Wang, Lin Bai
Abstract—In millimeter wave (mmWave) systems,
desirable spectral efficiency can be realized by the hybrid
beamformer in which a large sized analog beamformer
and a small sized baseband digital beamformer are
cascade-connected together to reduce the system cost.
However, most of works focus on the beamforming (or
combining) method design with an impractical analog
beamformer where the infinite-resolution phase shifts
(PSs) are adopted. In this paper, a more practical hybrid
beamformer with low-resolution PSs is considered and the
hybrid receiver beamforming method under the multiuser
uplink communication circumstance is studied. Since the
system performance is mainly constrained by the inter-
user interference, we propose a novel two-stage hybrid
receiver beamforming against the inter-user interference
with comparable computational complexity than that of
the recently presented method. Moreover, to enhance
the performance of systems with many users, we propose
a novel multiuser selection algorithm by exploiting the
multiuser diversity gain. Finally, from the simulation
results, we can verify the superiority of the proposed
method over the comparing method in error probability
and spectrum efficiency.
Keywords—mmWave, hybrid beamformer, detection,
multiuser selection, error probability
Manuscript received Aug. 15, 2019; accepted Sep. 19, 2019. This work
was supported by the National Key Research and Development Program of
China (Grant No. 2017YFB0503002) and the National Natural Science Foun-
dation of China (Grant No. 61922010). The associate editor coordinating the
review of this paper and approving it for publication was W. Zhang.
C. Han, J. X. Wang. School of Electronic and Information Engineering,
Beihang University, Beijing 100191, China (e-mail: chaohan@buaa.edu.cn;
wang jx@buaa.edu.cn).
J. C. Wang. Peng Cheng Laboratory, Shenzhen 518055, China (e-mail:
wangjc61s@163.com).
L. Bai. School of Cyber Science and Technology, Beihang University,
Beijing 100191, China; Beijing Laboratory for General Aviation Technology,
Beihang University, Beijing 100191, China (e-mail: l.bai@buaa.edu.cn).
I. INTRODUCTION
M
illimeter wave (mmWave) communications have been
regarded as one of the key techniques for the future
wireless communications system owing to its large amount
of available spectrum. To achieve high spectral efficiency,
lots of antennas should be equipped at the base station (BS)
side to overcome the high propagation loss at mmWave
frequency effectively, by exploiting array gain and multi-
plex gain. However, compared with the traditional small-
scale digital multiple-input-multiple-output (MIMO) system,
mmWave MIMO system with such a full-digital structure is
impractical due to the expensive hardware and prohibitive
power consumption of radio frequency (RF) chains
[1]
.
To address the above problems, the hybrid-architecture
beamformer (or combiner) was proposed for the mmWave
system to approximate the full-digital system, where the
analog beamformer and the baseband digital beamformer
are cascade-connected together. In Ref. [2], the orthogo-
nal matching pursuit hybrid beamforming algorithm was pro-
posed to maximize the mutual information by the developed
iterative process. In Ref. [3], the relationship between the
spectrum efficiency and the number of the RF chains was ana-
lyzed, while a heuristic hybrid beamforming scheme and an it-
erative gradient method were proposed in Refs. [4] and [5], re-
spectively. Since the analog beamformer and the digital beam-
former are coupled with each other (which means the beam-
forming design is difficult to be solved with a low-complexity
general solution), to simplify the joint iterative beamforming
process, two-stage-based hybrid beamforming methods were
proposed in which the digital part would be derived as the
analog part was determined
[6,7]
. However, these algorithms
are not applicable to practical mmWave communication sys-
tems since the infinite-resolution phase shift (PS) utilized in
these works is impractical
[8]
.
Hybrid beamforming system with low-resolution PS imple-
mentation has been carried out recently. A channel match-
ing method presented in Ref. [9] aims at steering the analog
beams to the direction of different users, where the correla-
tion among different users (or analog beams) has not been