3 research outputs found
A Distributed Multi-RF Chain Hybrid mmWave Scheme for Small-cell Systems
This paper proposes a distributed hybrid millimeter wave (mmWave) scheme to
exploit the structure of a Densely Deployed Distributed (DDD)
small-cell-base-stations (SBSs) system for serving multiple users in a
geographic area. Both the SBSs and the users are equipped with full access
hybrid architectures with multi-antenna arrays and multiple radio frequency
chains. Unlike the conventional cellular networks where users receive data
streams from their nearest BSs, the users in our proposed scheme simultaneously
receive data streams from different SBSs. With appropriate design of analog
beamformers, co-channel multi-data-stream interference can be mitigated and the
extra spatial degrees of freedom induced by the geographic distributed SBSs are
exploited for data multiplexing. Analytical and simulation results show that
the proposed scheme can improve the system sum-rate considerably, especially
when the number of scattering components in millimeter wave channels is
limited.Comment: 7 pages, 6 figures, accepted by ICC 201
A Two-Stage Beam Alignment Framework for Hybrid MmWave Distributed Antenna Systems
In this paper, we investigate the beam alignment problem in millimeter-wave
(mmWave) distributed antenna systems where a home base station communicates
with multiple users through a number of distributed remote radio units (RRUs).
Specifically, a two-stage schedule-and-align (TSSA) scheme is proposed to
facilitate efficient communications. In the first stage, a coarse beam scanning
over the entire angular space is performed while beam indices and the
corresponding peak-to-background ratios of the received power-angle-spectrum
are obtained from users' feedback. Then, by exploiting the user feedback, an
efficient user scheduling algorithm is developed to improve the system spectral
efficiency and to reduce the system misalignment probability. Next, the second
stage of beam search is performed by each RRU with reconfigured search angles,
search steps, and power levels to obtain a refined beam alignment. Simulation
results show that the proposed TSSA scheme can significantly outperform the
conventional one-stage method in both centralized and distributed mmWave
systems in terms of beam alignment accuracy and spectral efficiency.Comment: 5 pages, 5 figures, accepted by IEEE SPAWC 201
Performance Analysis and Design of Non-orthogonal Multiple Access for Wireless Communications
In this thesis, we study performance analysis and resource allocation designs
for non-orthogonal multiple access (NOMA) in wireless communication systems. In
contrast to conventional orthogonal multiple access (OMA) schemes, NOMA allows
multiple users to share the same degree of freedom via superposition coding and
the successive interference cancelation (SIC) decoding. Inspired by the solid
foundations from the information theory perspective, NOMA has rekindled the
interests of researchers as a benefit of the recent advancement in signal
processing and silicon technologies. However, comprehensive performance
analysis on NOMA and practical resource allocation designs to exploit potential
gains of NOMA in terms of spectral and energy efficiency have not been fully
studied and investigated in the literature. This thesis attempts to address
these problems by providing a unified performance analysis and a systematic
resource allocation design for NOMA in wireless communication systems.Comment: Thesis Submitted to The University of New South Wale