186 research outputs found
Sum Throughput Maximization in Multi-Tag Backscattering to Multiantenna Reader
Backscatter communication (BSC) is being realized as the core technology for
pervasive sustainable Internet-of-Things applications. However, owing to the
resource-limitations of passive tags, the efficient usage of multiple antennas
at the reader is essential for both downlink excitation and uplink detection.
This work targets at maximizing the achievable sum-backscattered-throughput by
jointly optimizing the transceiver (TRX) design at the reader and
backscattering coefficients (BC) at the tags. Since, this joint problem is
nonconvex, we first present individually-optimal designs for the TRX and BC. We
show that with precoder and {combiner} designs at the reader respectively
targeting downlink energy beamforming and uplink Wiener filtering operations,
the BC optimization at tags can be reduced to a binary power control problem.
Next, the asymptotically-optimal joint-TRX-BC designs are proposed for both low
and high signal-to-noise-ratio regimes. Based on these developments, an
iterative low-complexity algorithm is proposed to yield an efficient
jointly-suboptimal design. Thereafter, we discuss the practical utility of the
proposed designs to other application settings like wireless powered
communication networks and BSC with imperfect channel state information.
Lastly, selected numerical results, validating the analysis and shedding novel
insights, demonstrate that the proposed designs can yield significant
enhancement in the sum-backscattered throughput over existing benchmarks.Comment: 17 pages, 5 figures, accepted for publication in IEEE Transactions on
Communication
Hybrid Precoder and Combiner Design with Low Resolution Phase Shifters in mmWave MIMO Systems
Millimeter wave (mmWave) communications have been considered as a key
technology for next generation cellular systems and Wi-Fi networks because of
its advances in providing orders-of-magnitude wider bandwidth than current
wireless networks. Economical and energy efficient analog/digial hybrid
precoding and combining transceivers have been often proposed for mmWave
massive multiple-input multiple-output (MIMO) systems to overcome the severe
propagation loss of mmWave channels. One major shortcoming of existing
solutions lies in the assumption of infinite or high-resolution phase shifters
(PSs) to realize the analog beamformers. However, low-resolution PSs are
typically adopted in practice to reduce the hardware cost and power
consumption. Motivated by this fact, in this paper, we investigate the
practical design of hybrid precoders and combiners with low-resolution PSs in
mmWave MIMO systems. In particular, we propose an iterative algorithm which
successively designs the low-resolution analog precoder and combiner pair for
each data stream, aiming at conditionally maximizing the spectral efficiency.
Then, the digital precoder and combiner are computed based on the obtained
effective baseband channel to further enhance the spectral efficiency. In an
effort to achieve an even more hardware-efficient large antenna array, we also
investigate the design of hybrid beamformers with one-bit resolution (binary)
PSs, and present a novel binary analog precoder and combiner optimization
algorithm with quadratic complexity in the number of antennas. The proposed
low-resolution hybrid beamforming design is further extended to multiuser MIMO
communication systems. Simulation results demonstrate the performance
advantages of the proposed algorithms compared to existing low-resolution
hybrid beamforming designs, particularly for the one-bit resolution PS
scenario
A survey on hybrid beamforming techniques in 5G : architecture and system model perspectives
The increasing wireless data traffic demands have driven the need to explore suitable spectrum regions for meeting the projected requirements. In the light of this, millimeter wave (mmWave) communication has received considerable attention from the research community. Typically, in fifth generation (5G) wireless networks, mmWave massive multiple-input multiple-output (MIMO) communications is realized by the hybrid transceivers which combine high dimensional analog phase shifters and power amplifiers with lower-dimensional digital signal processing units. This hybrid beamforming design reduces the cost and power consumption which is aligned with an energy-efficient design vision of 5G. In this paper, we track the progress in hybrid beamforming for massive MIMO communications in the context of system models of the hybrid transceivers' structures, the digital and analog beamforming matrices with the possible antenna configuration scenarios and the hybrid beamforming in heterogeneous wireless networks. We extend the scope of the discussion by including resource management issues in hybrid beamforming. We explore the suitability of hybrid beamforming methods, both, existing and proposed till first quarter of 2017, and identify the exciting future challenges in this domain
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